The Foundation and Development of Computer Assisted Instruction in the Field of Reading from Its Inception to the Present.

ERIC Educational Resources Information Center

Zuberman, Lea K.

This critical review and evaluation of the literature covers the field of computer assisted instruction (CAI) and reading from its inception to the present day. Seventeen research studies are discussed as well as four surveys of previous research in this field. Major issues addressed include the effectiveness of CAI and computer managed…

Chaotic structures of nonlinear magnetic fields. I - Theory. II - Numerical results

NASA Technical Reports Server (NTRS)

Lee, Nam C.; Parks, George K.

1992-01-01

A study of the evolutionary properties of nonlinear magnetic fields in flowing MHD plasmas is presented to illustrate that nonlinear magnetic fields may involve chaotic dynamics. It is shown how a suitable transformation of the coupled equations leads to Duffing's form, suggesting that the behavior of the general solution can also be chaotic. Numerical solutions of the nonlinear magnetic field equations that have been cast in the form of Duffing's equation are presented.

Study Choice and Career Development in STEM Fields: An Overview and Integration of the Research

ERIC Educational Resources Information Center

van Tuijl, Cathy; van der Molen, Juliette H.

2016-01-01

Although science, technology, engineering and mathematics (STEM) study paths and STEM work fields may be relatively difficult and therefore not appropriate for everyone, too many children prematurely exclude STEM-related study and work options, based on negative images of the field or negative ability beliefs. In the present article, we provide an…

Field of Study, Learning Styles, and Language Learning Strategies of University Students: Are There Any Relations?

ERIC Educational Resources Information Center

Sahragard, Rahman; Khajavi, Yaser; Abbasian, Reza

2016-01-01

The present study aimed to investigate the possible relationships between field of study, learning style preferences, and language learning strategies among university students majoring in the fields of arts and humanities, science, engineering, social sciences, and English as a foreign language. To this end, 376 university students completed the…

Visual Field Asymmetries in Attention Vary with Self-Reported Attention Deficits

ERIC Educational Resources Information Center

Poynter, William; Ingram, Paul; Minor, Scott

2010-01-01

The purpose of this study was to determine whether an index of self-reported attention deficits predicts the pattern of visual field asymmetries observed in behavioral measures of attention. Studies of "normal" subjects do not present a consistent pattern of asymmetry in attention functions, with some studies showing better left visual field (LVF)…

Hemisphere division and its effect on selective attention: a generality examination of Lavie's load theory.

PubMed

Nishimura, Ritsuko; Yoshizaki, Kazuhito; Kato, Kimiko; Hatta, Takeshi

2009-01-01

The present study examined the role of visual presentation mode (unilateral vs. bilateral visual fields) on attentional modulation. We examined whether or not the presentation mode affects the compatibility effect, using a paradigm involving two task-relevant letter arrays. Sixteen participants identified a target letter among task-relevant letters while ignoring either a compatible or incompatible distracter letter that was presented to both hemispheres. Two letters arrays were presented to visual fields, either unilaterally or bilaterally. Results indicated that the compatibility effect was greater in bilateral than in unilateral visual field conditions. Findings support the assumption that the two hemispheres have separate attentional resources.

Field Placement Treatments: A Comparative Study

ERIC Educational Resources Information Center

Parkison, Paul T.

2008-01-01

Field placement within teacher education represents a topic of interest for all preservice teacher programs. Present research addresses a set of important questions regarding field placement: (1) What pedagogical methodologies facilitate deep learning during field experiences? (2) Is there a significant difference in treatment effect for…

Electromagnetic Field Penetration Studies

NASA Technical Reports Server (NTRS)

Deshpande, M.D.

2000-01-01

A numerical method is presented to determine electromagnetic shielding effectiveness of rectangular enclosure with apertures on its wall used for input and output connections, control panels, visual-access windows, ventilation panels, etc. Expressing EM fields in terms of cavity Green's function inside the enclosure and the free space Green's function outside the enclosure, integral equations with aperture tangential electric fields as unknown variables are obtained by enforcing the continuity of tangential electric and magnetic fields across the apertures. Using the Method of Moments, the integral equations are solved for unknown aperture fields. From these aperture fields, the EM field inside a rectangular enclosure due to external electromagnetic sources are determined. Numerical results on electric field shielding of a rectangular cavity with a thin rectangular slot obtained using the present method are compared with the results obtained using simple transmission line technique for code validation. The present technique is applied to determine field penetration inside a Boeing-757 by approximating its passenger cabin as a rectangular cavity filled with a homogeneous medium and its passenger windows by rectangular apertures. Preliminary results for, two windows, one on each side of fuselage were considered. Numerical results for Boeing-757 at frequencies 26 MHz, 171-175 MHz, and 428-432 MHz are presented.

International Relations as a Field of Study in the Canadian System of Higher Education

ERIC Educational Resources Information Center

Istomina, Kateryna

2015-01-01

The research presents an attempt to investigate the current state of international relations as a field of study in the context of higher education system in Canada. It contains a general overview of the field of study, focusing predominantly on the role and function of the given academic discipline. The scientific investigation covers the issue…

Mapping Women's and Gender Studies in the Academic Field in Slovenia

ERIC Educational Resources Information Center

Gaber, Milica Antic

2017-01-01

The aim of the present paper is to map the development of women's and gender studies (WGS) in the academic field in Slovenia. Slovenia is the first of the former Yugoslav state republics in which WGS have succeeded in entering the academic field and becoming part of institutionalised university study. In this paper we will ask the following…

Periodic MHD flow with temperature dependent viscosity and thermal conductivity past an isothermal oscillating cylinder

NASA Astrophysics Data System (ADS)

Ahmed, Rubel; Rana, B. M. Jewel; Ahmmed, S. F.

2017-06-01

Temperature dependent viscosity and thermal conducting heat and mass transfer flow with chemical reaction and periodic magnetic field past an isothermal oscillating cylinder have been considered. The partial dimensionless equations governing the flow have been solved numerically by applying explicit finite difference method with the help Compaq visual 6.6a. The obtained outcome of this inquisition has been discussed for different values of well-known flow parameters with different time steps and oscillation angle. The effect of chemical reaction and periodic MHD parameters on the velocity field, temperature field and concentration field, skin-friction, Nusselt number and Sherwood number have been studied and results are presented by graphically. The novelty of the present problem is to study the streamlines by taking into account periodic magnetic field.

Engaging the Borders: Empathy, Religious Studies, and Pre-Professional Fields

ERIC Educational Resources Information Center

Trothen, Tracy J.

2016-01-01

This article proposes that religious studies instructors can gain pedagogical insights regarding the value and teaching of empathy from pre-professional health care and counseling fields. I present research findings from these fields to support claims that empathic skills are teachable. I then show that empathy has been established within the…

Supporting Medical Students to Do International Field Research: A Case Study

ERIC Educational Resources Information Center

Pearson, Stephen; Parr, Jennifer; Ullah, Zafar; Omar, Maye

2014-01-01

Field research can benefit medical students' learning through experiential engagement with research and personal exposure to foreign health systems. However, the off-campus nature of the activity raises challenges for teachers. This article presents a case study that illustrates the benefits and challenges of organising a field research project…

[The influence of application of a low-frequency magnetic field on the serum corticosterone level (an experimental study)].

PubMed

Alabovskiĭ, V V; Gotovskiĭ, M Iu; Vinokurov, A A; Maslov, O V

2013-01-01

The results of analysis of the literature publications suggest the necessity of experimental studies aimed at investigation of modulating effect of low-frequency magnetic fields on endocrine organs. The present study was carried out using 200 outbred white male rats (body weight 200-220 g). Corticosterone was measured in blood sera following the application of a low-frequency magnetic field (20 and 53 Hz with induction from 0.4 to 6 mT) generated by a Mini-Expert-T apparatus for induction magnetic therapy during 30 minutes. It was shown that the application of the alternating magnetic field to the adrenal region of the rats in the selected frequency and induction ranges caused a significant increase in the serum corticosterone levels. The results of the present study on the hormonal activity of rat adrenals give reason to consider the influence of the alternating magnetic fields as being modulatory. Analysis of the data thus obtained has demonstrated the non-linear dependence of glucocorticoid activity of the rat adrenal glands on the induction strength of the alternating magnetic field.

New paradigms for the statistics profession

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

Iman, R.L.

This paper is a presentation made in support of the statistics profession. This field can say it has had a major impact in most major fields of study presently undertaken by man, yet it is not perceived as an important, or critical field of study. It is not a growth field either, witness the almost level number of faculty and new PhD`s produced over the past twenty years. The author argues the profession must do a better job of selling itself to the students it educates. Awaken them to the impact of statistics in their lives and their business worlds,more » so that they see beyond the formulae to the application of these principles.« less

Distinct regions of the hippocampus are associated with memory for different spatial locations.

PubMed

Jeye, Brittany M; MacEvoy, Sean P; Karanian, Jessica M; Slotnick, Scott D

2018-05-15

In the present functional magnetic resonance imaging (fMRI) study, we aimed to evaluate whether distinct regions of the hippocampus were associated with spatial memory for items presented in different locations of the visual field. In Experiment 1, during the study phase, participants viewed abstract shapes in the left or right visual field while maintaining central fixation. At test, old shapes were presented at fixation and participants classified each shape as previously in the "left" or "right" visual field followed by an "unsure"-"sure"-"very sure" confidence rating. Accurate spatial memory for shapes in the left visual field was isolated by contrasting accurate versus inaccurate spatial location responses. This contrast produced one hippocampal activation in which the interaction between item type and accuracy was significant. The analogous contrast for right visual field shapes did not produce activity in the hippocampus; however, the contrast of high confidence versus low confidence right-hits produced one hippocampal activation in which the interaction between item type and confidence was significant. In Experiment 2, the same paradigm was used but shapes were presented in each quadrant of the visual field during the study phase. Accurate memory for shapes in each quadrant, exclusively masked by accurate memory for shapes in the other quadrants, produced a distinct activation in the hippocampus. A multi-voxel pattern analysis (MVPA) of hippocampal activity revealed a significant correlation between behavioral spatial location accuracy and hippocampal MVPA accuracy across participants. The findings of both experiments indicate that distinct hippocampal regions are associated with memory for different visual field locations. Copyright © 2018 Elsevier B.V. All rights reserved.

Spray combustion under oscillatory pressure conditions

NASA Technical Reports Server (NTRS)

Jacobs, H. R.; Santoro, R. J.

1991-01-01

The performance and stability of liquid rocket engines is often argued to be significantly impacted by atomization and droplet vaporization processes. In particular, combustion instability phenomena may result from the interactions between the oscillating pressure field present in the rocket combustor and the fuel and oxidizer injection process. Few studies have been conducted to examine the effects of oscillating pressure fields on spray formation and its evolution under rocket engine conditions. The pressure study is intended to address the need for such studies. In particular, two potentially important phenomena are addressed in the present effort. The first involves the enhancement of the atomization process for a liquid jet subjected to an oscillating pressure field of known frequency and amplitude. The objective of this part of the study is to examine the coupling between the pressure field and or the resulting periodically perturbed velocity field on the breakup of the liquid jet. In particular, transverse mode oscillations are of interest since such modes are considered of primary importance in combustion instability phenomena. The second aspect of the project involves the effects of an oscillating pressure on droplet coagulation and secondary atomization. The objective of this study is to examine the conditions under which phenomena following the atomization process are affected by perturbations to the pressure or velocity fields. Both coagulation and represent a coupling mechanism between the pressure field and the energy release process in rocket combustors. It is precisely this coupling which drives combustion instability phenomena. Consequently, the present effort is intended to provide the fundamental insights needed to evaluate these processes as important mechanisms in liquid rocket instability phenomena.

A study on the influence of corona on currents and electromagnetic fields predicted by a nonlinear lightning return-stroke model

NASA Astrophysics Data System (ADS)

De Conti, Alberto; Silveira, Fernando H.; Visacro, Silvério

2014-05-01

This paper investigates the influence of corona on currents and electromagnetic fields predicted by a return-stroke model that represents the lightning channel as a nonuniform transmission line with time-varying (nonlinear) resistance. The corona model used in this paper allows the calculation of corona currents as a function of the radial electric field in the vicinity of the channel. A parametric study is presented to investigate the influence of corona parameters, such as the breakdown electric field and the critical electric field for the stable propagation of streamers, on predicted currents and electromagnetic fields. The results show that, regardless of the assumed corona parameters, the incorporation of corona into the nonuniform and nonlinear transmission line model under investigation modifies the model predictions so that they consistently reproduce most of the typical features of experimentally observed lightning electromagnetic fields and return-stroke speed profiles. In particular, it is shown that the proposed model leads to close vertical electric fields presenting waveforms, amplitudes, and decay with distance in good agreement with dart leader electric field changes measured in triggered lightning experiments. A comparison with popular engineering return-stroke models further confirms the model's ability to predict consistent electric field waveforms in the close vicinity of the channel. Some differences observed in the field amplitudes calculated with the different models can be related to the fact that current distortion, while present in the proposed model, is ultimately neglected in the considered engineering return-stroke models.

Hemispheric specialization in quantification processes.

PubMed

Pasini, M; Tessari, A

2001-01-01

Three experiments were carried out to study hemispheric specialization for subitizing (the rapid enumeration of small patterns) and counting (the serial quantification process based on some formal principles). The experiments consist of numerosity identification of dot patterns presented in one visual field, with a tachistoscopic technique, or eye movements monitored through glasses, and comparison between centrally presented dot patterns and lateralized tachistoscopically presented digits. Our experiments show left visual field advantage in the identification and comparison tasks in the subitizing range, whereas right visual field advantage has been found in the comparison task for the counting range.

Several examples where turbulence models fail in inlet flow field analysis

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.

1993-01-01

Computational uncertainties in turbulence modeling for three dimensional inlet flow fields include flows approaching separation, strength of secondary flow field, three dimensional flow predictions of vortex liftoff, and influence of vortex-boundary layer interactions; computational uncertainties in vortex generator modeling include representation of generator vorticity field and the relationship between generator and vorticity field. The objectives of the inlet flow field studies presented in this document are to advance the understanding, prediction, and control of intake distortion and to study the basic interactions that influence this design problem.

Field Evaluation of the Pedostructure-Based Model (Kamel®)

USDA-ARS?s Scientific Manuscript database

This study involves a field evaluation of the pedostructure-based model Kamel and comparisons between Kamel and the Hydrus-1D model for predicting profile soil moisture. This paper also presents a sensitivity analysis of Kamel with an evaluation field site used as the base scenario. The field site u...

European Youth Research: Development, Debates, Demands

ERIC Educational Resources Information Center

Chisholm, Lynne

2006-01-01

This chapter presents the development of European youth research as a distinctive field of study. It draws attention to the sociopolitical context in which the field has emerged, outlines the key dimensions of the field's agenda, reports on significant facets of theory and research development to date, and briefly considers the field's…

Grammatical number agreement processing using the visual half-field paradigm: an event-related brain potential study.

PubMed

Kemmer, Laura; Coulson, Seana; Kutas, Marta

2014-02-01

Despite indications in the split-brain and lesion literatures that the right hemisphere is capable of some syntactic analysis, few studies have investigated right hemisphere contributions to syntactic processing in people with intact brains. Here we used the visual half-field paradigm in healthy adults to examine each hemisphere's processing of correct and incorrect grammatical number agreement marked either lexically, e.g., antecedent/reflexive pronoun ("The grateful niece asked herself/*themselves…") or morphologically, e.g., subject/verb ("Industrial scientists develop/*develops…"). For reflexives, response times and accuracy of grammaticality decisions suggested similar processing regardless of visual field of presentation. In the subject/verb condition, we observed similar response times and accuracies for central and right visual field (RVF) presentations. For left visual field (LVF) presentation, response times were longer and accuracy rates were reduced relative to RVF presentation. An event-related brain potential (ERP) study using the same materials revealed similar ERP responses to the reflexive pronouns in the two visual fields, but very different ERP effects to the subject/verb violations. For lexically marked violations on reflexives, P600 was elicited by stimuli in both the LVF and RVF; for morphologically marked violations on verbs, P600 was elicited only by RVF stimuli. These data suggest that both hemispheres can process lexically marked pronoun agreement violations, and do so in a similar fashion. Morphologically marked subject/verb agreement errors, however, showed a distinct LH advantage. Copyright © 2013 Elsevier B.V. All rights reserved.

Grammatical number agreement processing using the visual half-field paradigm: An event-related brain potential study

PubMed Central

Kemmer, Laura; Coulson, Seana; Kutas, Marta

2014-01-01

Despite indications in the split-brain and lesion literatures that the right hemisphere is capable of some syntactic analysis, few studies have investigated right hemisphere contributions to syntactic processing in people with intact brains. Here we used the visual half-field paradigm in healthy adults to examine each hemisphere’s processing of correct and incorrect grammatical number agreement marked either lexically, e.g., antecedent/reflexive pronoun (“The grateful niece asked herself/*themselves…”) or morphologically, e.g., subject/verb (“Industrial scientists develop/*develops…”). For reflexives, response times and accuracy of grammaticality decisions suggested similar processing regardless of visual field of presentation. In the subject/verb condition, we observed similar response times and accuracies for central and right visual field (RVF) presentations. For left visual field (LVF) presentation, response times were longer and accuracy rates were reduced relative to RVF presentation. An event-related brain potential (ERP) study using the same materials revealed similar ERP responses to the reflexive pronouns in the two visual fields, but very different ERP effects to the subject/verb violations. For lexically marked violations on reflexives, P600 was elicited by stimuli in both the LVF and RVF; for morphologically marked violations on verbs, P600 was elicited only by RVF stimuli. These data suggest that both hemispheres can process lexically marked pronoun agreement violations, and do so in a similar fashion. Morphologically marked subject/verb agreement errors, however, showed a distinct LH advantage. PMID:24326084

Segmented-field radiography in scoliosis

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

Daniel, W.W.; Barnes, G.T.; Nasca, R.J.

1985-02-01

A method of scoliosis imaging using segmented fields is presented. The method is advantageous for patients requiring serial radiographic monitoring, as it results in markedly reduced radiation doses to critical organs, particularly the breast. Absorbed dose to the breast was measured to be 8.8 mrad (88 ..mu..Gy) for a full-field examination and 0.051 mrad (5.1 ..mu..Gy) for the segmented-field study. The segmented-field technique also results in improved image quality. Experience with 53 studies in 23 patients is reported.

Report of the Field and Laboratory Utilization Study Group. Appendix

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

None

1975-12-01

These appendices (ERDA organization and management, summary of other resources, and FLU study considerations/inputs) provide detailed and quantitative information in support of the findings and recommendations presented in the report of the field and laboratory utilization study group. (RWR)

How International Field Experiences Promote Cross-Cultural Awareness in Preservice Teachers through Experiential Learning: Findings from a Six-Year Collective Case Study

ERIC Educational Resources Information Center

Malewski, Erik; Sharma, Suniti; Phillion, JoAnn

2012-01-01

Background/Context: The article examines how international field experiences promote cross-cultural awareness in U.S. American preservice teachers through experiential learning. The findings presented here are based on a 6-year study of a short-term study abroad program in Honduras that included an international field experience component and took…

Health psychology in Ghana: A review of the multidisciplinary origins of a young sub-field and its future prospects.

PubMed

de-Graft Aikins, Ama

2018-03-01

This article presents a historical overview of psychology applied to health and health psychology in Ghana. A brief history of health, illness and healthcare in Ghana is introduced. Then, the history of psychology in Ghana is presented, with signposts of the major turns in the field in relation to psychology and other disciplines applied to health and the emergence of health psychology as a sub-field. Selected health psychology studies are reviewed to highlight ideological trends in the field. Finally, future prospects are considered in terms of how the sub-field can transition into an established critical field with unique contributions to make to global health psychology.

Measurements of Solar Vector Magnetic Fields

NASA Technical Reports Server (NTRS)

Hagyard, M. J. (Editor)

1985-01-01

Various aspects of the measurement of solar magnetic fields are presented. The four major subdivisions of the study are: (1) theoretical understanding of solar vector magnetic fields; (3) techniques for interpretation of observational data; and (4) techniques for data display.

Effective field theory of statistical anisotropies for primordial bispectrum and gravitational waves

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

Rostami, Tahereh; Karami, Asieh; Firouzjahi, Hassan, E-mail: t.rostami@ipm.ir, E-mail: karami@ipm.ir, E-mail: firouz@ipm.ir

2017-06-01

We present the effective field theory studies of primordial statistical anisotropies in models of anisotropic inflation. The general action in unitary gauge is presented to calculate the leading interactions between the gauge field fluctuations, the curvature perturbations and the tensor perturbations. The anisotropies in scalar power spectrum and bispectrum are calculated and the dependence of these anisotropies to EFT couplings are presented. In addition, we calculate the statistical anisotropy in tensor power spectrum and the scalar-tensor cross correlation. Our EFT approach incorporates anisotropies generated in models with non-trivial speed for the gauge field fluctuations and sound speed for scalar perturbationsmore » such as in DBI inflation.« less

Field study of a shredded-tire embankment.

DOT National Transportation Integrated Search

1994-01-01

This report presents interim data from the ongoing field study of an experimental shredded-tire embankment constructed near Williamsburg, Virginia. Approximately 1.7 million tires were used. This constitutes the largest reported use to date of waste ...

George Herbert Mead, Curriculum Theorist: The Curriculum Field and the Problem of Social Control.

ERIC Educational Resources Information Center

Franklin, Barry M.

This paper is one of three presented at a symposium intended to suggest how historical studies of the curriculum field can aid in identifying alternative perspectives to the prevailing scientific-technical perspective, an orientation that has dominated the curriculum field since its inception as a formal area of study. This paper contends that…

Nursery practices, seedling sizes, and field performance.

Treesearch

William I. Stein

1988-01-01

Highlights are presented from a large cooperative study to determine the combined effects of nursery cultural practices on the initial size and subsequent field performance of 2+0 Douglas-fir seedlings. The study involved seven sources of stock produced in three different nurseries and field plantings made over 3 years on 28 sites in southwestern Oregon. Seedbed...

Report of the panel on geopotential fields: Gravity field, section 8

NASA Technical Reports Server (NTRS)

Anderson, Allen Joel; Kaula, William M.; Lazarewics, Andrew R.; Lefebvre, Michel; Phillips, Roger J.; Rapp, Richard H.; Rummel, Reinhard F.; Smith, David E.; Tapley, Byron D.; Zlotnick, Victor

1991-01-01

The objective of the Geopotential Panel was to develop a program of data acquisition and model development for the Earth's gravity and magnetic fields that meet the basic science requirements of the solid Earth and ocean studies. Presented here are the requirements for gravity information and models through the end of the century, the present status of our knowledge, data acquisition techniques, and an outline of a program to meet the requirements.

Effect of radio frequency waves of electromagnetic field on the tubulin.

PubMed

Taghi, Mousavi; Gholamhosein, Riazi; Saeed, Rezayi-Zarchi

2013-09-01

Microtubules (MTs) are macromolecular structures consisting of tubulin heterodimers and present in almost every eukaryotic cell. MTs fulfill all conditions for generation of electromagnetic field and are electrically polar due to the electrical polarity of a tubulin heterodimer. The calculated static electric dipole moment of about 1000 Debye makes them capable of being aligned parallel to the applied electromagnetic field direction. In the present study, the tubulin heterodimers were extracted and purified from the rat brains. MTs were obtained by polymerization in vitro. Samples of microtubules were adsorbed in the absence and in the presence of electromagnetic fields with radio frequency of 900 Hz. Our results demonstrate the effect of electromagnetic field with 900 Hz frequency to change the structure of MTs. In this paper, a related patent was used that will help to better understand the studied subject.

Analytical and experimental study of axisymmetric truncated plug nozzle flow fields

NASA Technical Reports Server (NTRS)

Muller, T. J.; Sule, W. P.; Fanning, A. E.; Giel, T. V.; Galanga, F. L.

1972-01-01

Experimental and analytical investigation of the flow field and base pressure of internal-external-expansion truncated plug nozzles are discussed. Experimental results for two axisymmetric, conical plug-cylindrical shroud, truncated plug nozzles are presented for both open and closed wake operations. These results include extensive optical and pressure data covering nozzle flow field and base pressure characteristics, diffuser effects, lip shock strength, Mach disc behaviour, and the recompression and reverse flow regions. Transonic experiments for a special planar transonic section are presented. An extension of the analytical method of Hall and Mueller to include the internal shock wave from the shroud exit is presented for closed wake operation. Results of this analysis include effects on the flow field and base pressure of ambient pressure ratio, nozzle geometry, and the ratio of specific heats. Static thrust is presented as a function of ambient pressure ratio and nozzle geometry. A new transonic solution method is also presented.

RECRUITMENT AND FIELD SAMPLING IN THE CTEPP NORTH CAROLINA AND OHIO FIELD STUDIES

EPA Science Inventory

Recruiting study participants is always a challenge for researchers. It is more of a challenge when researchers have to recruit participants for a study involving intrusive, burdensome data collection activities. In this presentation, we describe our recruitment strategies and ...

Geoelectric monitoring at the Boulder magnetic observatory

USGS Publications Warehouse

Blum, Cletus; White, Tim; Sauter, Edward A.; Stewart, Duff; Bedrosian, Paul A.; Love, Jeffrey J.

2017-01-01

Despite its importance to a range of applied and fundamental studies, and obvious parallels to a robust network of magnetic-field observatories, long-term geoelectric field monitoring is rarely performed. The installation of a new geoelectric monitoring system at the Boulder magnetic observatory of the US Geological Survey is summarized. Data from the system are expected, among other things, to be used for testing and validating algorithms for mapping North American geoelectric fields. An example time series of recorded electric and magnetic fields during a modest magnetic storm is presented. Based on our experience, we additionally present operational aspects of a successful geoelectric field monitoring system.

Field Evaluation of Advanced Methods of Subsurface Exploration for Transit Tunneling

DOT National Transportation Integrated Search

1980-06-01

This report presents the results of a field evaluation of advanced methods of subsurface exploration on an ongoing urban rapid transit tunneling project. The objective of this study is to evaluate, through a field demonstration project, the feasibili...

Using Educational Data Mining Methods to Assess Field-Dependent and Field-Independent Learners' Complex Problem Solving

ERIC Educational Resources Information Center

Angeli, Charoula; Valanides, Nicos

2013-01-01

The present study investigated the problem-solving performance of 101 university students and their interactions with a computer modeling tool in order to solve a complex problem. Based on their performance on the hidden figures test, students were assigned to three groups of field-dependent (FD), field-mixed (FM), and field-independent (FI)…

Gauge Fields in Homogeneous and Inhomogeneous Cosmologies

NASA Astrophysics Data System (ADS)

Darian, Bahman K.

Despite its formidable appearance, the study of classical Yang-Mills (YM) fields on homogeneous cosmologies is amenable to a formal treatment. This dissertation is a report on a systematic approach to the general construction of invariant YM fields on homogeneous cosmologies undertaken for the first time in this context. This construction is subsequently followed by the investigation of the behavior of YM field variables for the most simple of self-gravitating YM fields. Particularly interesting was a dynamical system analysis and the discovery of chaotic signature in the axially symmetric Bianchi I-YM cosmology. Homogeneous YM fields are well studied and are known to have chaotic properties. The chaotic behavior of YM field variables in homogeneous cosmologies might eventually lead to an invariant definition of chaos in (general) relativistic cosmological models. By choosing the gauge fields to be Abelian, the construction and the field equations presented so far reduce to that of electromagnetic field in homogeneous cosmologies. A perturbative analysis of gravitationally interacting electromagnetic and scalar fields in inhomogeneous cosmologies is performed via the Hamilton-Jacobi formulation of general relativity. An essential feature of this analysis is the spatial gradient expansion of the generating functional (Hamilton principal function) to solve the Hamiltonian constraint. Perturbations of a spatially flat Friedman-Robertson-Walker cosmology with an exponential potential for the scalar field are presented.

The features of the Cosmic Web unveiled by the flip-flop field

NASA Astrophysics Data System (ADS)

Shandarin, Sergei F.; Medvedev, Mikhail V.

2017-07-01

Currently the dark matter environment is widely accepted as a framework for understanding of the observed structure in the universe. N-body simulations are indispensable for the analysis of the formation and evolution of the dark matter web. Two primary fields - density and velocity fields - are used in most of studies. Dark matter provides two additional fields that are unique for collisionless media only. They are the multistream field in Eulerian space and flip-flop field in Lagrangian space. The flip-flop field represents the number of sign reversals of an elementary volume of each collisionless fluid element. This field can be estimated by counting the sign reversals of the Jacobian at each particle at every time step of the simulation. The Jacobian is evaluated by numerical differentiation of the Lagrangian submanifold, I.e. the three-dimensional dark matter sheet in the six-dimensional space formed by three Lagrangian and three Eulerian coordinates. We present the results of the statistical study of the evolution of the flip-flop field from z = 50 to the present time z = 0. A number of statistical characteristics show that the pattern of the flip-flop field remains remarkably stable from z ≈ 30 to the present time. As a result the flip-flop field evaluated at z = 0 stores a wealth of information about the dynamical history of the dark matter web. In particular one of the most intriguing properties of the flip-flop is a unique capability to preserve the information about the merging history of haloes.

Hyperbolic-symmetry vector fields.

PubMed

Gao, Xu-Zhen; Pan, Yue; Cai, Meng-Qiang; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian

2015-12-14

We present and construct a new kind of orthogonal coordinate system, hyperbolic coordinate system. We present and design a new kind of local linearly polarized vector fields, which is defined as the hyperbolic-symmetry vector fields because the points with the same polarization form a series of hyperbolae. We experimentally demonstrate the generation of such a kind of hyperbolic-symmetry vector optical fields. In particular, we also study the modified hyperbolic-symmetry vector optical fields with the twofold and fourfold symmetric states of polarization when introducing the mirror symmetry. The tight focusing behaviors of these vector fields are also investigated. In addition, we also fabricate micro-structures on the K9 glass surfaces by several tightly focused (modified) hyperbolic-symmetry vector fields patterns, which demonstrate that the simulated tightly focused fields are in good agreement with the fabricated micro-structures.

Conventional Gymnasium vs. Geodesic Field House. A Comparative Study of High School Physical Education and Assembly Facilities.

ERIC Educational Resources Information Center

Educational Facilities Labs., Inc., New York, NY.

A description is presented of the design features of a high school's geodesic dome field house. Following consideration of various design features and criteria for the physical education facility, a comprehensive analysis is given of comparative costs of a geodesic dome field house and conventional gymnasium. On the basis of the study it would…

Maintaining perceptual constancy while remaining vigilant: left hemisphere change blindness and right hemisphere vigilance.

PubMed

Vos, Leia; Whitman, Douglas

2014-01-01

A considerable literature suggests that the right hemisphere is dominant in vigilance for novel and survival-related stimuli, such as predators, across a wide range of species. In contrast to vigilance for change, change blindness is a failure to detect obvious changes in a visual scene when they are obscured by a disruption in scene presentation. We studied lateralised change detection using a series of scenes with salient changes in either the left or right visual fields. In Study 1 left visual field changes were detected more rapidly than right visual field changes, confirming a right hemisphere advantage for change detection. Increasing stimulus difficulty resulted in greater right visual field detections and left hemisphere detection was more likely when change occurred in the right visual field on a prior trial. In Study 2 an intervening distractor task disrupted the influence of prior trials. Again, faster detection speeds were observed for the left visual field changes with a shift to a right visual field advantage with increasing time-to-detection. This suggests that a right hemisphere role for vigilance, or catching attention, and a left hemisphere role for target evaluation, or maintaining attention, is present at the earliest stage of change detection.

Localization of firearm projectiles in the human body using a superconducting quantum interference device magnetometer: A theoretical study

NASA Astrophysics Data System (ADS)

Hall Barbosa, C.

2004-06-01

A technique had been previously developed, based on magnetic field measurements using a superconducting quantum interference device sensor, to localize in three dimensions steel needles lost in the human body. In all six cases that were treated until now, the technique allowed easy surgical localization of the needles with high accuracy. The technique decreases, by a large factor, the surgery time for foreign body extraction, and also reduces the generally high odds of failure. The method is accurate, noninvasive, and innocuous, and with clear clinical importance. Despite the importance of needle localization, the most prevalent foreign body in the modern society is the firearm projectile (bullet), generally composed of lead, a paramagnetic material, thus not presenting a remanent magnetic field as steel needles do. On the other hand, since lead is a good conductor, eddy current detection techniques can be employed, by applying an alternating magnetic field with the aid of excitation coils. The primary field induces eddy currents on the lead, which in turn generate a secondary magnetic field that can be detected by a magnetometer, and give information about position and volume of the conducting foreign body. In this article we present a theoretical study for the development of a localization technique for lead bullets inside the human body. Initially, we present a model for the secondary magnetic field generated by the bullet, given a known applied field. After that, we study possible excitation systems, and propose a localization algorithm based on the detected magnetic field.

Right hemispheric dominance and interhemispheric cooperation in gaze-triggered reflexive shift of attention.

PubMed

Okada, Takashi; Sato, Wataru; Kubota, Yasutaka; Toichi, Motomi; Murai, Toshiya

2012-03-01

The neural substrate for the processing of gaze remains unknown. The aim of the present study was to clarify which hemisphere dominantly processes and whether bilateral hemispheres cooperate with each other in gaze-triggered reflexive shift of attention. Twenty-eight normal subjects were tested. The non-predictive gaze cues were presented either in unilateral or bilateral visual fields. The subjects localized the target as soon as possible. Reaction times (RT) were shorter when gaze-cues were congruent toward than away from targets, whichever visual field they were presented in. RT were shorter in left than right visual field presentations. RT in mono-directional bilateral presentations were shorter than both of those in left and right presentations. When bi-directional bilateral cues were presented, RT were faster when valid cues were presented in the left than right visual fields. The right hemisphere appears to be dominant, and there is interhemispheric cooperation in gaze-triggered reflexive shift of attention. © 2012 The Authors. Psychiatry and Clinical Neurosciences © 2012 Japanese Society of Psychiatry and Neurology.

Federal Research Action Plan (FRAP) on Recycled Tire Crumb Used on Playing Fields and Playgrounds (5th Annual Recycled Rubber Products Technology Conference)

EPA Science Inventory

This presentation provides an overview and status update of the Federal Research Action Plan (FRAP) on Recycled Tire Crumb Used on Playing Fields and Playgrounds. The presentation includes information on Federal research activities, stakeholder engagement, other studies, and the ...

Experience of 16 years and its associated challenges in the Field Epidemiology Training Program in Korea.

PubMed

Lee, Moo-Sik; Kim, Eun-Young; Lee, Sang-Won

2017-01-01

The field epidemiologist system of South Korea, which employs public health doctors who are relatively more readily available, was created in 1999 to ensure a ready supply of experts for epidemiological investigations and enable an effective response for new and reemerging infectious diseases. However, the 2015 outbreak of Middle East Respiratory Syndrome revealed limitations in the existing systems of management of field epidemiologists and communicable diseases. The present study aims to evaluate data on current states, administrative reports, and other literature on the field epidemiologist system that has been in place in South Korea for 16 years since 1999 and to suggest appropriate future improvements in this system. By suggesting methods to evaluate the field epidemiologist system and training programs and by suggesting ways for the Korea Centers for Disease Control and Prevention to conduct evaluations on its own, the present study provides supporting evidence for improvement of systems for training of experts in epidemiological investigations. Moreover, based on the findings, this study also suggests methods to systematically train experts in communicable diseases management and a sustainable system to establish the basis of and develop strategies for a systematic and phased management of field epidemiologist training programs. The present study suggests the possibility of establishing dedicated training facilities, revising the guidelines on training and improvement of the competency of public health experts, while not limiting the scope of application to communicable diseases.

Statistical Study of Interplanetary Coronal Mass Ejections with Strong Magnetic Fields

NASA Astrophysics Data System (ADS)

Murphy, Matthew E.

Coronal Mass Ejections (CMEs) with strong magnetic fields (B ) are typically associated with significant Solar Energetic Particle (SEP) events, high solar wind speed and solar flare events. Successful prediction of the arrival time of a CME at Earth is required to maximize the time available for satellite, infrastructure, and space travel programs to take protective action against the coming flux of high-energy particles. It is known that the magnetic field strength of a CME is linked to the strength of a geomagnetic storm on Earth. Unfortunately, the correlations between strong magnetic field CMEs from the entire sun (especially from the far side or non-Earth facing side of the sun) to SEP and flare events, solar source regions and other relevant solar variables are not well known. New correlation studies using an artificial intelligence engine (Eureqa) were performed to study CME events with magnetic field strength readings over 30 nanoteslas (nT) from January 2010 to October 17, 2014. This thesis presents the results of this study, validates Eureqa to obtain previously published results, and presents previously unknown functional relationships between solar source magnetic field data, CME initial speed and the CME magnetic field. These new results enable the development of more accurate CME magnetic field predictions and should help scientists develop better forecasts thereby helping to prevent damage to humanity's space and Earth assets.

Investigation of Unsteady Flow Behavior in Transonic Compressor Rotors with LES and PIV Measurements

NASA Technical Reports Server (NTRS)

Hah, Chunill; Voges, Melanie; Mueller, Martin; Schiffer, Heinz-Peter

2009-01-01

In the present study, unsteady flow behavior in a modern transonic axial compressor rotor is studied in detail with large eddy simulation (LES) and particle image velocimetry (PIV). The main purpose of the study is to advance the current understanding of the flow field near the blade tip in an axial transonic compressor rotor near the stall and peak-efficiency conditions. Flow interaction between the tip leakage vortex and the passage shock is inherently unsteady in a transonic compressor. Casing-mounted unsteady pressure transducers have been widely applied to investigate steady and unsteady flow behavior near the casing. Although many aspects of flow have been revealed, flow structures below the casing cannot be studied with casing-mounted pressure transducers. In the present study, unsteady velocity fields are measured with a PIV system and the measured unsteady flow fields are compared with LES simulations. The currently applied PIV measurements indicate that the flow near the tip region is not steady even at the design condition. This self-induced unsteadiness increases significantly as the compressor rotor operates near the stall condition. Measured data from PIV show that the tip clearance vortex oscillates substantially near stall. The calculated unsteady characteristics of the flow from LES agree well with the PIV measurements. Calculated unsteady flow fields show that the formation of the tip clearance vortex is intermittent and the concept of vortex breakdown from steady flow analysis does not seem to apply in the current flow field. Fluid with low momentum near the pressure side of the blade close to the leading edge periodically spills over into the adjacent blade passage. The present study indicates that stall inception is heavily dependent on unsteady behavior of the flow field near the leading edge of the blade tip section for the present transonic compressor rotor.

Reponse Dynamique D'un Panneau Soumis a un Environnement Acoustique Reverberant

NASA Astrophysics Data System (ADS)

Nelisse, Hugues

1995-01-01

The present thesis deals with the problem of the dynamic response of a homeogenous flexible panel immersed in a reverberant field. This problem takes place in the framework of aerospace problems in which satellites substructures are submitted to high acoustic levels during the launchers lift-off. The thesis is divided in four main parts. The first one presents an integral formulation that allows to treat the case of a flexible panel placed in a rectangular room. A semi-analytical resolution is used to identify the two main physical unknowns of the problem, the acoustic pressure jump across the panel and the panel deflection. The second part is dedicated to the study of the notion of diffuse field. Through a bibliographic review, two indicators are used to characterize the sound field in the room and in the free field. Precise criterions related to the modal density of the room are discussed. Analysis and discussion on the conditions which allow the establishment of a diffuse field are also presented. In the third part, a theoretical formulation which allows to treat the problem of an unbaffled panel submitted to an acoustic excitation in the free field is presented. The singularity problem due to the use of the free-space Green's function is overcame by the use of a variational principle. A semi-analytical approach is used to solve the linear system of equations. Emphasis is put on the fact that the excitation is acoustic. The theory is validated with the help of an existing boundary element numerical code. The last part is first dedicated to a comparative study of the two developed approaches and to a phenomenological study. Studies of the effect of the structural damping on the panel vibrations are presented as well as analysis of some different approximations generally used in this type of problem.

The fragmentation of ethanol cation under an electric field: An ab initio/RRKM study

NASA Astrophysics Data System (ADS)

Lu, Hsiu-Feng; Li, F.-Y.; Lin, Chun-Chin; Nagaya, K.; Chao, Ito; Lin, S. H.

2007-08-01

We present a theoretical study of ethanol cation under an electric field due to the existence of laser field in order to understand the influence of electric field on the mass spectrum of ethanol. The electric field was applied to the four major reaction channels of an ethanol cation, such as the conversion between C 2H 5OH + and c-C 2H 5OH +, CH 3-elimination and two α-H-eliminations, respectively. The correlation between product distribution and field strength is quite complex due to the different responses of the reactants and transition states toward the external electric field. This makes the product distribution change as field strength varies.

Helicons in Unbounded Plasmas.

PubMed

Stenzel, R L; Urrutia, J M

2015-05-22

Helicons are whistler modes with helical phase fronts. They have been studied in solid state plasmas and in discharge tubes where boundaries and nonuniformities are ever present. The present work shows that helicons also exist in unbounded and uniform plasmas, thereby bridging the fields of laboratory and space plasma physics. First measurements of helicon field lines in three dimensional space are presented. Helicons with negative and positive mode numbers can propagate with equal amplitudes.

Spirituality, religion, and health: over the last 15 years of field research (1999-2013).

PubMed

Lucchetti, Giancarlo; Lucchetti, Alessandra Lamas Granero

2014-01-01

Although several studies have examined the contribution of specific countries, journals, and authors in different scientific disciplines, little is known about the contribution of different world countries, journals, and authors to scientific research in the field of "Spirituality, religion, and health" (S/R). The present study aims to analyze the last 15 years of research in the field of spirituality and religiousness (S/R) through a bibliometric analysis. Using the Pubmed database, we retrieved all articles related to S/R field for the period 1999-2013. We then estimated the total number of publications, number of articles published per year, articles published per country, journals with most publications in S/R field, most productive authors, and most used keywords. We found a growth of publications in the last years, most from the United States and the United Kingdom and published in the English language. Noteworthy, some developing countries such as India, Brazil, Israel, and Iran are at higher positions in this list. The S/R articles were published in journals embracing all fields of research, including high impact journals. In the present study, we took a closer look at the field of "Spirituality, religion, and health," showing that this field of research has been constantly growing and consolidating in the scientific community.

Dynamics of photogenerated carriers near magnetic field driven quantum phase transition in aperiodic multiple quantum wells

NASA Astrophysics Data System (ADS)

Tito, M. A.; Pusep, Yu A.

2018-01-01

Time-resolved magneto-photoluminescence was employed to study the magnetic field induced quantum phase transition separating two phases with different distributions of electrons over quantum wells in an aperiodic multiple quantum well, embedded in a wide AlGaAs parabolic quantum well. Intensities, broadenings and recombination times attributed to the photoluminescence lines emitted from individual quantum wells of the multiple quantum well structure were measured as a function of the magnetic field near the transition. The presented data manifest themselves to the magnetic field driven migration of the free electrons between the quantum wells of the studied multiple quantum well structure. The observed charge transfer was found to influence the screening of the multiple quantum well and disorder potentials. Evidence of the localization of the electrons in the peripheral quantum wells in strong magnetic field is presented.

COSMOS-e'-soft Higgsotic attractors

NASA Astrophysics Data System (ADS)

Choudhury, Sayantan

2017-07-01

In this work, we have developed an elegant algorithm to study the cosmological consequences from a huge class of quantum field theories (i.e. superstring theory, supergravity, extra dimensional theory, modified gravity, etc.), which are equivalently described by soft attractors in the effective field theory framework. In this description we have restricted our analysis for two scalar fields - dilaton and Higgsotic fields minimally coupled with Einstein gravity, which can be generalized for any arbitrary number of scalar field contents with generalized non-canonical and non-minimal interactions. We have explicitly used R^2 gravity, from which we have studied the attractor and non-attractor phases by exactly computing two point, three point and four point correlation functions from scalar fluctuations using the In-In (Schwinger-Keldysh) and the δ N formalisms. We have also presented theoretical bounds on the amplitude, tilt and running of the primordial power spectrum, various shapes (equilateral, squeezed, folded kite or counter-collinear) of the amplitude as obtained from three and four point scalar functions, which are consistent with observed data. Also the results from two point tensor fluctuations and the field excursion formula are explicitly presented for the attractor and non-attractor phase. Further, reheating constraints, scale dependent behavior of the couplings and the dynamical solution for the dilaton and Higgsotic fields are also presented. New sets of consistency relations between two, three and four point observables are also presented, which shows significant deviation from canonical slow-roll models. Additionally, three possible theoretical proposals have presented to overcome the tachyonic instability at the time of late time acceleration. Finally, we have also provided the bulk interpretation from the three and four point scalar correlation functions for completeness.

A region of intense plasma wave turbulence on auroral field lines

NASA Technical Reports Server (NTRS)

Gurnett, D. A.; Frank, L. A.

1976-01-01

This report presents a detailed study of the plasma wave turbulence observed by HAWKEYE-1 and IMP-6 on high latitude auroral field lines and investigates the relationship of this turbulence to magnetic field and plasma measurements obtained in the same region.

Characterization of field isolates of Magnaporthe oryzae with mating type, DNA fingerprinting, and pathogenicity assays

USDA-ARS?s Scientific Manuscript database

Due to the harmful nature of the rice blast fungus, Magnaporthe oryzae, it is beneficial to characterize field isolates to help aid in the deployment of resistance (R) genes in rice. In the present study, 190 field isolates of M. oryzae, collected from rice fields of Yunnan province in China, were a...

Cyanobacteria, Toxins and Indicators: Field Monitoring,Treatment Facility Monitoring and Treatment Studies

EPA Science Inventory

This presentation is a compilation of harmful algal bloom (HAB) related field monitoring data from the 2015 bloom season, treatment plant monitoring data from the 2013 and 2014 bloom seasons, and bench-scale treatment study data from 2015.

Universities and Fields of Study in Argentina: A Public-Private Comparison from the Supply and Demand Side. PROPHE Working Paper Series. WP No. 15

ERIC Educational Resources Information Center

Rabossi, Marcelo

2010-01-01

Private higher education literature recognizes large public-private differentiation in terms of field of study. Relative to public counterparts, private universities tend to offer their services in fields that require low initial investments and present at least relatively attractive internal private rates of return. Thus, the main objective of…

Bats Respond to Very Weak Magnetic Fields

PubMed Central

Tian, Lan-Xiang; Pan, Yong-Xin; Metzner, Walter; Zhang, Jin-Shuo; Zhang, Bing-Fang

2015-01-01

How animals, including mammals, can respond to and utilize the direction and intensity of the Earth’s magnetic field for orientation and navigation is contentious. In this study, we experimentally tested whether the Chinese Noctule, Nyctalus plancyi (Vespertilionidae) can sense magnetic field strengths that were even lower than those of the present-day geomagnetic field. Such field strengths occurred during geomagnetic excursions or polarity reversals and thus may have played an important role in the evolution of a magnetic sense. We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north. As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here), the bats still responded by positioning themselves at the magnetic north. When the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT), despite the fact that the artificial field orientation was opposite to the natural geomagnetic field (P<0.05). Hence, N. plancyi is able to detect the direction of a magnetic field even at 1/5th of the present-day field strength. This high sensitivity to magnetic fields may explain how magnetic orientation could have evolved in bats even as the Earth’s magnetic field strength varied and the polarity reversed tens of times over the past fifty million years. PMID:25922944

Bats respond to very weak magnetic fields.

PubMed

Tian, Lan-Xiang; Pan, Yong-Xin; Metzner, Walter; Zhang, Jin-Shuo; Zhang, Bing-Fang

2015-01-01

How animals, including mammals, can respond to and utilize the direction and intensity of the Earth's magnetic field for orientation and navigation is contentious. In this study, we experimentally tested whether the Chinese Noctule, Nyctalus plancyi (Vespertilionidae) can sense magnetic field strengths that were even lower than those of the present-day geomagnetic field. Such field strengths occurred during geomagnetic excursions or polarity reversals and thus may have played an important role in the evolution of a magnetic sense. We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north. As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here), the bats still responded by positioning themselves at the magnetic north. When the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT), despite the fact that the artificial field orientation was opposite to the natural geomagnetic field (P<0.05). Hence, N. plancyi is able to detect the direction of a magnetic field even at 1/5th of the present-day field strength. This high sensitivity to magnetic fields may explain how magnetic orientation could have evolved in bats even as the Earth's magnetic field strength varied and the polarity reversed tens of times over the past fifty million years.

Electric fields measured by ISEE-1 within and near the neutral sheet during quiet and active times

NASA Technical Reports Server (NTRS)

Cattell, C. A.; Mozer, F. S.

1982-01-01

An understanding of the physical processes occurring in the magnetotail and plasmasheet during different interplanetary magnetic field orientations and differing levels of ground magnetic activity is crucial for the development of a theory of energy transfer from the solar wind to the particles which produce auroral arcs. In the present investigation, the first observations of electric fields during neutral sheet crossings are presented, taking into account the statistical correlations of the interplanetary magnetic field direction and ground activity with the character of the electric field. The electric field data used in the study were obtained from a double probe experiment on the ISEE-1 satellite. The observations suggest that turbulent electric and magnetic fields are intimately related to plasma acceleration in the neutral sheet and to the processes which create auroral particles.

Laboratory and field investigations of marsh edge erosion

USDA-ARS?s Scientific Manuscript database

This chapter presents the laboratory experiments and field observations of marsh edge erosion. The marsh retreat rate in a field study site in Terrebonne Bay, Louisiana, was measured using GPS systems and aerial photographs. The wave environment was also measured in order to correlate the marsh edge...

Canine parvovirus in vaccinated dogs: a field study.

PubMed

Miranda, C; Thompson, G

2016-04-16

The authors report a field study that investigated the canine parvovirus (CPV) strains present in dogs that developed the disease after being vaccinated. Faecal samples of 78 dogs that have been vaccinated against CPV and later presented with clinical signs suspected of parvovirus infection were used. Fifty (64.1 per cent) samples tested positive by PCR for CPV. No CPV vaccine type was detected. The disease by CPV-2b occurred in older and female dogs when compared with that by CPV-2c. The clinical signs presented by infected dogs were similar when any of both variants were involved. In most cases of disease, the resulting infection by field variants occurred shortly after CPV vaccination. Two dogs that had been subjected to a complete vaccination schedule and presented with clinical signs after 10 days of vaccination, had the CPV-2c variant associated. The phylogenetic studies showed a close relationship of the isolates in vaccinated dogs to European field strains. Despite the limited sample size in this study, the findings point to the significance of the continuous molecular typing of the virus as a tool to monitor the prevalent circulating CPV strains and access the efficacy of current vaccines. Adjustments on the vaccine types to be used may have to be evaluated again according to each epidemiological situation in order to achieve the dog's optimal immune protection against CPV.

A Sociological Description of Changes in the Intellectual Field of Mathematics Education Research: Implications for the Identities of Academics.

ERIC Educational Resources Information Center

Tsatsaroni, Anna; Lerman, Stephen; Xu, Guo-Rong

This paper presents aspects of a study that aims to describe and make sense of changes over time in the intellectual field of mathematics education research. Drawing on the work of B. Bernstein, especially his essay on intellectual fields and knowledge structures, the paper seeks to raise questions about the fields standing in the wider field of…

Topside ionosphere of Mars: Variability, transient layers, and the role of crustal magnetic fields

NASA Astrophysics Data System (ADS)

Gopika, P. G.; Venkateswara Rao, N.

2018-04-01

The topside ionosphere of Mars is known to show variability and transient topside layers. In this study, we analyzed the electron density profiles measured by the radio occultation technique aboard the Mars Global Surveyor spacecraft to study the topside ionosphere of Mars. The electron density profiles that we used in the present study span between 1998 and 2005. All the measurements are done from the northern high latitudes, except 220 profiles which were measured in the southern hemisphere, where strong crustal magnetic fields are present. We binned the observations into six measurement periods: 1998, 1999-north, 1999-south, 2000-2001, 2002-2003, and 2004-2005. We found that the topside ionosphere in the southern high latitudes is more variable than that from the northern hemisphere. This feature is clearly seen with fluctuations of wavelengths less than 20 km. Some of the electron density profiles show a transient topside layer with a local maximum in electron density between 160 km and 210 km. The topside layer is more prone to occur in the southern hemispheric crustal magnetic field regions than in the other regions. In addition, the peak density of the topside layer is greater in regions of strong crustal magnetic fields than in other regions. The variability of the topside ionosphere and the peak density of the topside layer, however, do not show one-to-one correlation with the strength of the crustal magnetic fields and magnetic field inclination. The results of the present study are discussed in the light of current understanding on the topside ionosphere, transient topside layers, and the role of crustal magnetic fields on plasma motions.

Particle Diffusion in Chaotic Magnetic Fields Generated by Asymmetric Current Configurations

NASA Astrophysics Data System (ADS)

Ram, A. K.; Dasgupta, B.

2008-12-01

The observed cross-field diffusion of charged particles in cosmic rays is assumed to be due to the chaotic nature of the interplanetary/intergalactic magnetic fields. Among the classic works on this subject have been those of Parker [1] and Jokipii [2]. Parker considered the passage of cosmic ray particles and energetic solar particles in a large scale magnetic field containing small scale irregularities. In the context of cosmic ray propagation, Jokipii considered a small fluctuating component, added on to a uniform magnetic field, to study the spatial transport of particles. In these studies the irregular component of the magnetic field is prescribed in an ad hoc fashion. In contrast, we consider asymmetric, nonlinear, steady-state magnetic fields, in three spatial dimensions, generated by currents flowing in circular loops and straight lines [3]. These magnetic fields are completely deterministic and, for certain range of parameters, chaotic. We will present analytical and numerical studies on the spatial characteristics of these fields. The motion of charged particles in the nonlinear and chaotic magnetic fields is determined using the Lorentz equation. A particle moving in a deterministic chaotic magnetic field superposed on a uniform background magnetic field is found to undergo spatial transport. This shows that chaotic magnetic fields generated by simple current configurations can produce cross-field diffusion. A detailed analysis of particle motion and diffusion along with application to space plasmas will be presented. [1] E.N. Parker, Planet. Space Sci. 13, 9 (1965). [2] J.R. Jokipii, Astrophys. J. 146, 480 (1966), and J.R. Jokipii, Astrophys. J. 149, 405 (1967). [3] A.K. Ram and B. Dasgupta, Eos Trans. AGU 87 (52), Fall Meet. Suppl. Abstract NG31B-1593 (2006); and Eos Trans. AGU 88 (52), Fall Meet. Suppl. Abstract NG21B-0522 (2007).

An introduction to genetic quality in the context of sexual selection.

PubMed

Pitcher, Trevor E; Mays, Herman L

2008-09-01

This special issue of Genetica brings together empirical researchers and theoreticians to present the latest on the evolutionary ecology of genetic quality in the context of sexual selection. The work comes from different fields of study including behavioral ecology, quantitative genetics and molecular genetics on a diversity of organisms using different approaches from comparative studies, mathematical modeling, field studies and laboratory experiments. The papers presented in this special issue primarily focus on genetic quality in relation to (1) sources of genetic variation, (2) polyandry, (3) new theoretical developments and (4) comprehensive reviews.

Investigating Effects of Invasive Species on Plant Community Structure

ERIC Educational Resources Information Center

Franklin, Wilfred

2008-01-01

In this article, the author presents a field study project that explores factors influencing forest community structure and lifts the veil off of "plant blindness." This ecological study consists of three laboratories: (1) preliminary field trip to the study site; (2) plant survey; and (3) analyzing plant community structure with descriptive…

Electromagnetism of Bacterial Growth

NASA Astrophysics Data System (ADS)

Ainiwaer, Ailiyasi

2011-10-01

There has been increasing concern from the public about personal health due to the significant rise in the daily use of electrical devices such as cell phones, radios, computers, GPS, video games and television. All of these devices create electromagnetic (EM) fields, which are simply magnetic and electric fields surrounding the appliances that simultaneously affect the human bio-system. Although these can affect the human system, obstacles can easily shield or weaken the electrical fields; however, magnetic fields cannot be weakened and can pass through walls, human bodies and most other objects. The present study was conducted to examine the possible effects of bacteria when exposed to magnetic fields. The results indicate that a strong causal relationship is not clear, since different magnetic fields affect the bacteria differently, with some causing an increase in bacterial cells, and others causing a decrease in the same cells. This phenomenon has yet to be explained, but the current study attempts to offer a mathematical explanation for this occurrence. The researchers added cultures to the magnetic fields to examine any effects to ion transportation. Researchers discovered ions such as potassium and sodium are affected by the magnetic field. A formula is presented in the analysis section to explain this effect.

Critical Experiences for Field Geologists: Emergent Themes in Interest Development

ERIC Educational Resources Information Center

LaDue, Nicole D.; Pacheco, Heather A.

2013-01-01

Geoscience education researchers are working to understand how we can most effectively increase our overall geoscience workforce capacity. The present study employed an inductive approach to explore the critical experiences that led to the persistence of successful field geologists in this STEM field. Interviews with 29 professional field…

Visual half-field presentations of incongruent color words: effects of gender and handedness.

PubMed

Franzon, M; Hugdahl, K

1986-09-01

Right-handed (dextral) and left-handed (sinistral) males and females (N = 15) were compared for language lateralization in a visual half-field (VHF) incongruent color-words paradigm. The paradigm consists of repeated brief (less than 200 msec) presentations of color-words written in an incongruent color. Presentations are either to the right or to the left of center fixation. The task of the subject is to report the color the word is written in on each trial, ignoring the color-word. Color-bars and congruent color-words were used as control stimuli. Vocal reaction time (VRT) and error frequency were used as dependent measures. The logic behind the paradigm is that incongruent color-words should lead to a greater cognitive conflict when presented in the half-field contralateral to the dominant hemisphere. The results showed significantly longer VRTs in the right half-field for the dextral subjects. Furthermore, significantly more errors were observed in the male dextral group when the incongruent stimuli were presented in the right half-field. There was a similar trend in the data for the sinistral males. No differences between half-fields were observed for the female groups. It is concluded that the present results strengthen previous findings from our laboratory (Hugdahl and Franzon, 1985) that the incongruent color-words paradigm is a useful non-invasive technique for the study of lateralization in the intact brain.

White Sands Missile Range 2007 Urban Study: Flow and Stability Around a Single Building Volume 1: Field Study Overview

DTIC Science & Technology

2007-09-01

results in his 2003 North Atlantic Treaty Organisation (NATO) presentation (Banff, Canada) (3). 1.2.2 WSMR 2005 Urban Study (W05US) In 2005 March...used in the W03US and W05US urban field studies at WSMR, NM (section 1). This building was concrete cinder-block with a nearly flat roof. To the...prior to the field study execution, the two 2-story- tall trees on the northeast and southeast corners of the building were unexpectedly removed

Repellency Awareness Graphic: Informational Presentation for EPA’s Human Studies Review Board

EPA Pesticide Factsheets

Informational Presentation for EPA’s Human Studies Review Board April 9, 2014, by Rose Kyprianou, Field and External Affairs Division, and Kelly Sherman, Immediate Office, Office of Pesticide Programs.

Field study learning model to introduce environmental health problems to medical students at the faculty of medicine, University of Brawijaya, Malang, Indonesia

NASA Astrophysics Data System (ADS)

Zuhriyah, Lilik; Setijowati, Nanik; Andarini, Sri

2017-11-01

Some diseases in the community have a relationship with the environment. Therefore, medical students need to be exposed early to environmental problems in the community. The aim of this paper is to explain the role of field studies for medical students in introducing environmental health problems at an early stage. Field studies were applied by the Department of Public Health in 2005-2006 and 164 students from Semester II, which come from two classes, were required to join it. The portion score of the field study was 10%. Each class consisted of ten groups. Each group consisted of approximately eight students. Each group took different topics/targets of observation. These included ecological farming, household waste management, communal waste management, family medicine plants, food home industry, food street vendors, slaughterhouses, traditional markets, management of communal waste water, and recycling home industry. Each group observed in a community and interviewed related informants. Students were required to make a report and present it in their class. At the end of the exam, students were required to assess the benefit of this activity using a range of 1 (minimal) to 5 (maximal). The students considered the benefits of the field study method, giving an average score of 3.9 and 3.95 for presentation and discussion in class. Some students proposed to maintain field studies and discussion, and to conduct this method every semester with more time. Other students suggested that a lecturer accompany them in the field. Several students regretted unpunctual discussion time that reduced lecture time. The learning model of field study increased the students' interest in the subject of public health.

Spectroscopy of disordered low-field sites in Cr3+: Mullite glass ceramic

NASA Astrophysics Data System (ADS)

Knutson, Robert; Liu, Huimin; Yen, W. M.; Morgan, T. V.

1989-09-01

In this article we present results of optical and ESR studies that have allowed us to study the behavior of Cr3+ at disordered low-field sites within a mullite ceramic host. The results indicate that the existence of these low-field ions, which are likely at sites in regions of disorder, accounts for most of the spectroscopic anomalies previously noted in these materials. Furthermore, energy transfer from ordered high-field to disordered low-field ions is observed. The resulting complex spectra are deconvoluted by means of the recently developed technique of saturation-resolved fluorescence spectroscopy.

Numerically modelling the large scale coronal magnetic field

NASA Astrophysics Data System (ADS)

Panja, Mayukh; Nandi, Dibyendu

2016-07-01

The solar corona spews out vast amounts of magnetized plasma into the heliosphere which has a direct impact on the Earth's magnetosphere. Thus it is important that we develop an understanding of the dynamics of the solar corona. With our present technology it has not been possible to generate 3D magnetic maps of the solar corona; this warrants the use of numerical simulations to study the coronal magnetic field. A very popular method of doing this, is to extrapolate the photospheric magnetic field using NLFF or PFSS codes. However the extrapolations at different time intervals are completely independent of each other and do not capture the temporal evolution of magnetic fields. On the other hand full MHD simulations of the global coronal field, apart from being computationally very expensive would be physically less transparent, owing to the large number of free parameters that are typically used in such codes. This brings us to the Magneto-frictional model which is relatively simpler and computationally more economic. We have developed a Magnetofrictional Model, in 3D spherical polar co-ordinates to study the large scale global coronal field. Here we present studies of changing connectivities between active regions, in response to photospheric motions.

Spontaneous magnetization of quantum XY spin model in joint presence of quenched and annealed disorder

NASA Astrophysics Data System (ADS)

Bera, Anindita; Rakshit, Debraj; SenDe, Aditi; Sen, Ujjwal

2017-06-01

We investigate equilibrium statistical properties of the isotropic quantum XY spin-1/2 model in an external magnetic field when the interaction and field parts are subjected to quenched or annealed disorder or both. The randomness present in the system are termed annealed or quenched depending on the relation between two different time scales—the time scale associated with the equilibration of the randomness and the time of observation. Within a mean-field framework, we study the effects of disorders on spontaneous magnetization, both by perturbative and numerical techniques. Our primary interest is to understand the differences between quenched and annealed cases, and also to investigate the interplay when both of them are present in a system. We find that the magnetization survives in the presence of a unidirectional random field, irrespective of its nature, i.e., whether it is quenched or annealed. However, the field breaks the circular symmetry of the magnetization, and the system magnetizes in specific directions, parallel or transverse to the applied magnetic field. Interestingly, while the transverse magnetization is affected by the annealed disordered field, the parallel one remains unfazed by the same. Moreover, the annealed disorder present in the interaction term does not affect the system's spontaneous magnetization and the corresponding critical temperature, irrespective of the presence or absence of quenched or annealed disorder in the field term. We carry out a comparative study of these and all other different combinations of the disorders in the interaction and field terms, and point out their generic features.

Introducing time-dependent molecular fields: a new derivation of the wave equations

NASA Astrophysics Data System (ADS)

Baer, Michael

2018-02-01

This article is part of a series of articles trying to establish the concept molecular field. The theory that induced us to introduce this novel concept is based on the Born-Huang expansion as applied to the Schroedinger equation that describes the interaction of a molecular system with an external electric field. Assuming the molecular system is made up of two coupled adiabatic states the theory leads from a single spatial curl equation, two space-time curl equations and one single space-time divergent equation to a pair of decoupled wave equations usually encountered within the theory of fields. In the present study, just like in the previous study [see Baer et al., Mol. Phys. 114, 227 (2016)] the wave equations are derived for an electric field having two features: (a) its intensity is high enough; (b) its duration is short enough. Although not all the findings are new the derivation, in the present case, is new, straightforward, fluent and much friendlier as compared to the previous one and therefore should be presented again. For this situation the study reveals that the just described interaction creates two fields that coexist within a molecule: one is a novel vectorial field formed via the interaction of the electric field with the Born-Huang non-adiabatic coupling terms (NACTs) and the other is an ordinary, scalar, electric field essentially identical to the original electric field. Section 4 devoted to the visualization of the outcomes via two intersecting Jahn-Teller cones which contain NACTs that become singular at the intersection point of these cones. Finally, the fact that eventually we are facing a kind of a cosmic situation may bring us to speculate that singular NACTs are a result of cosmic phenomena. Thus, if indeed this singularity is somehow connected to reality then, like other singularities in physics, it is formed at (or immediately after) the Big Bang and consequently, guarantees the formation of molecules.

Relationships of anxiety scores to academy and field training performance of air traffic control specialists.

DOT National Transportation Integrated Search

1989-05-01

State-trait anxiety scores were used prior to the 1981 strike of air traffic control specialists (ATCSs) to estimate perceived levels of job stress in field studies of this occupational group. The present study assessed the relationship between anxie...

Longitudinal pavement joint performance : a field study of infrared heated and notched wedge joint construction.

DOT National Transportation Integrated Search

2012-12-01

This report presents the findings of a field study in Maine, constructed during summer 2012 using : two different joint technologies and an infrared heater. MaineDOT has previously used an infrared : heater and notch-wedge apparatus to improve longit...

Comparison of the effectiveness of real and virtual field trips in biology and ecology classes in lower secondary school based on the example of the Maribor island natural educational trail

NASA Astrophysics Data System (ADS)

Puhek, Miro

The present doctoral thesis presents a case study within the scope of which real and virtual field trips have been compared. The emphasis of the study was on determining the levels of knowledge gain effectiveness in the fields of biology and ecology in the final triad (third) of lower secondary school education. The analysis included students completing various tasks along the Maribor Island natural education trail, which had been digitized and inserted into Geopedia. The study was conducted in autumn of 2011 and included 464 students (enrolled in grades from 6 to 9) from 11 lower secondary schools located in the Maribor area. The results have generally shown minute differences between the levels of knowledge acquisition effectiveness between both field trips. During the real field trip, the majority of the students included in the study achieved better results particularly at tasks where they were able to benefit from first-hand experience. During the virtual field trip, individual students were more successful at tasks where they were allowed to access a computer in order to obtain additional information. Within the scope of the study, we had also surveyed lower secondary and secondary school teachers on the frequency of including field trips in the curriculum, on the obstacles that the teachers faced with regard to including field work in it, and on their views on real and virtual field trips. The survey included a total of 386 teachers, the majority whom were teaching the subjects of biology, geography, and natural science. The results have shown that the surveyed teachers regard field trips as a very important educational method that particularly encourages experience-based learning in nature. The views of the teachers on virtual field trips were generally positive, but only when regarded and applied as a supplemental teaching tool and not as a substitute for real field trips.

Combined effects of magnetic field and partial slip on obliquely striking rheological fluid over a stretching surface

NASA Astrophysics Data System (ADS)

Nadeem, S.; Mehmood, Rashid; Akbar, Noreen Sher

2015-03-01

This study explores the collective effects of partial slip and transverse magnetic field on an oblique stagnation point flow of a rheological fluid. The prevailing momentum equations are designed by manipulating Casson fluid model. By applying the suitable similarity transformations, the governing system of equations is being transformed into coupled nonlinear ordinary differential equations. The resulting system is handled numerically through midpoint integration scheme together with Richardson's extrapolation. It is found that both normal and tangential velocity profiles decreases with an increase in magnetic field as well as slip parameter. Streamlines pattern are presented to study the actual impact of slip mechanism and magnetic field on the oblique flow. A suitable comparison with the previous literature is also provided to confirm the accuracy of present results for the limiting case.

Evaluation of peripheral binocular visual field in patients with glaucoma: a pilot study

PubMed Central

Ana, Banc; Cristina, Stan; Dorin, Chiselita

2016-01-01

Objective: The objective of this study was to evaluate the peripheral binocular visual field (PBVF) in patients with glaucoma using the threshold strategy of Humphrey Field Analyzer. Methods: We conducted a case-control pilot study in which we enrolled 59 patients with glaucoma and 20 controls. All participants were evaluated using a custom PBVF test and central 24° monocular visual field tests for each eye using the threshold strategy. The central binocular visual field (CBVF) was predicted from the monocular tests using the most sensitive point at each field location. The glaucoma patients were grouped according to Hodapp classification and age. The PBVF was compared to controls and the relationship between the PBVF and CBVF was tested. Results: The areas of frame-induced artefacts were determined (over 50° in each temporal field, 24° superiorly and 45° inferiorly) and excluded from interpretation. The patients presented a statistically significant generalized decrease of the peripheral retinal sensitivity compared to controls for Hodapp initial stage - groups aged 50-59 (t = 11.93 > 2.06; p < 0.05) and 60-69 (t = 7.55 > 2.06; p < 0.05). For the initial Hodapp stage there was no significant relationship between PBVF and CBVF (r = 0.39). For the moderate and advanced Hodapp stages, the interpretation of data was done separately for each patient. Conclusions: This pilot study suggests that glaucoma patients present a decrease of PBVF compared to controls and CBVF cannot predict the PBVF in glaucoma. Abbreviations: CBVF = central binocular visual field, PBVF = peripheral binocular visual field, MD = mean deviation PMID:27220228

The Presentation Location of the Reference Stimuli Affects the Left-Side Bias in the Processing of Faces and Chinese Characters

PubMed Central

Li, Chenglin; Cao, Xiaohua

2017-01-01

For faces and Chinese characters, a left-side processing bias, in which observers rely more heavily on information conveyed by the left side of stimuli than the right side of stimuli, has been frequently reported in previous studies. However, it remains unclear whether this left-side bias effect is modulated by the reference stimuli's location. The present study adopted the chimeric stimuli task to investigate the influence of the presentation location of the reference stimuli on the left-side bias in face and Chinese character processing. The results demonstrated that when a reference face was presented in the left visual field of its chimeric images, which are centrally presented, the participants showed a preference higher than the no-bias threshold for the left chimeric face; this effect, however, was not observed in the right visual field. This finding indicates that the left-side bias effect in face processing is stronger when the reference face is in the left visual field. In contrast, the left-side bias was observed in Chinese character processing when the reference Chinese character was presented in either the left or right visual field. Together, these findings suggest that although faces and Chinese characters both have a left-side processing bias, the underlying neural mechanisms of this left-side bias might be different. PMID:29018391

The Presentation Location of the Reference Stimuli Affects the Left-Side Bias in the Processing of Faces and Chinese Characters.

PubMed

Li, Chenglin; Cao, Xiaohua

2017-01-01

For faces and Chinese characters, a left-side processing bias, in which observers rely more heavily on information conveyed by the left side of stimuli than the right side of stimuli, has been frequently reported in previous studies. However, it remains unclear whether this left-side bias effect is modulated by the reference stimuli's location. The present study adopted the chimeric stimuli task to investigate the influence of the presentation location of the reference stimuli on the left-side bias in face and Chinese character processing. The results demonstrated that when a reference face was presented in the left visual field of its chimeric images, which are centrally presented, the participants showed a preference higher than the no-bias threshold for the left chimeric face; this effect, however, was not observed in the right visual field. This finding indicates that the left-side bias effect in face processing is stronger when the reference face is in the left visual field. In contrast, the left-side bias was observed in Chinese character processing when the reference Chinese character was presented in either the left or right visual field. Together, these findings suggest that although faces and Chinese characters both have a left-side processing bias, the underlying neural mechanisms of this left-side bias might be different.

Effect of prior performance on subsequent performance evaluation by field independent-dependent raters.

PubMed

Sisco, Howard; Leventhal, Gloria

2007-12-01

The importance of accurate performance appraisals is central to many aspects of personnel activities in organizations. This study examined threats due to past performance to accuracy of evaluation of subsequent performance by raters differing in scores on field dependence. 162 college students were classified as Field-dependent (n = 81) or Field-independent (n = 81), using a median split on the Group Embedded Figures Test. Past performance (a lecture) was good or poor, presented directly via a videotape or indirectly via a written evaluation to the Field-independent or Field-dependent groups. Analysis indicated the hypothesized contrast effect (ratings in the opposite direction from that of prior ratings) in the Direct condition and an unexpected, albeit smaller, contrast effect in the Indirect condition. There were also differential effects of performance, presentation, and field dependency on rating of lecturer's style and ability.

Spatial encoding using the nonlinear field perturbations from magnetic materials.

PubMed

Karimi, Hirad; Dominguez-Viqueira, William; Cunningham, Charles H

2014-08-01

A proof-of-concept study was performed to assess the technical feasibility of using magnetic materials to generate spatial encoding fields. Spatially varying magnetic fields were generated by the placement of markers with different volume susceptibilities within the imaging volume. No linear gradients were used for spatial encoding during the signal acquisition. A signal-encoding model is described for reconstructing the images encoded with these field perturbations. Simulation and proof-of-concept experimental results are presented. Experiments were performed using field perturbations from a cylindrical marker as an example of the new encoding fields. Based on this experimental setup, annular rings were reconstructed from signals encoded with the new fields. Simulation results were presented for different acquisition parameters. Proof-of-concept was supported by the correspondence of regions in an image reconstructed from experimental data compared to those in a conventional gradient-echo image. Experimental results showed that inclusions of dimensions 1.5 mm in size could be resolved with the experimental setup. This study shows the technical feasibility of using magnetic markers to produce encoding fields. Magnetic materials will allow generating spatial encoding fields, which can be tailored to an imaging application with less complexity and at lower cost compared to the use of gradient inserts. Copyright © 2013 Wiley Periodicals, Inc.

The upper critical field of filamentary Nb3Sn conductors

NASA Astrophysics Data System (ADS)

Godeke, A.; Jewell, M. C.; Fischer, C. M.; Squitieri, A. A.; Lee, P. J.; Larbalestier, D. C.

2005-05-01

We have examined the upper critical field of a large and representative set of present multifilamentary Nb3Sn wires and one bulk sample over a temperature range from 1.4 K up to the zero-field critical temperature. Since all present wires use a solid-state diffusion reaction to form the A15 layers, inhomogeneities with respect to Sn content are inevitable, in contrast to some previously studied homogeneous samples. Our study emphasizes the effects that these inevitable inhomogeneities have on the field-temperature phase boundary. The property inhomogeneities are extracted from field-dependent resistive transitions which we find broaden with increasing inhomogeneity. The upper 90%-99% of the transitions clearly separates alloyed and binary wires but a pure, Cu-free binary bulk sample also exhibits a zero-temperature critical field that is comparable to the ternary wires. The highest μ0Hc2 detected in the ternary wires are remarkably constant: The highest zero-temperature upper critical fields and zero-field critical temperatures fall within 29.5±0.3 and 17.8±0.3K, respectively, independent of the wire layout. The complete field-temperature phase boundary can be described very well with the relatively simple Maki-DeGennes model using a two-parameter fit, independent of composition, strain state, sample layout, or applied critical state criterion.

Analysis of Mobile Source Air Toxics (MSATS)–Near-Road VOC and CarbonylConcentrations

EPA Science Inventory

This presentation examines data from a year-long study of measured near-road mobile source air toxic (MSAT) concentrations and compares these data with modeled 2005 National Air Toxic Assessment (NATA) results. Field study measurements were collected during a field campaign in ...

Genetic analysis without replications: Model evaluation and application in spring wheat

USDA-ARS?s Scientific Manuscript database

Genetic data collected from plant breeding and genetic studies may not be replicated in field designs even though field variation is present. In this study, we addressed this problem using spring wheat (Triticum eastivum L.) trial data collected from two locations. There were no intra-location repl...

Contemporary School Administration: An Introduction. Second Edition.

ERIC Educational Resources Information Center

Kowalski, Theodore J.

This book addresses career-related questions commonly asked by students beginning the study of school administration. As an introductory text, it presents a broad overview of school administration as a specialized field of study and as an applied field of professional practice. Special attention is given to describing the social, political, and…

Conceptual design of a compact high gradient quadrupole magnet of varying strength using permanent magnets

NASA Astrophysics Data System (ADS)

Sinha, Gautam

2018-02-01

A concept is presented to design magnets using cylindrical-shaped permanent-magnet blocks, where various types of magnetic fields can be produced by either rotating or varying the size of the magnetic blocks within a given mechanical structure. A general method is introduced to calculate the 3D magnetic field produced by a set of permanent magnets. An analytical expression of the 2D field and the condition to generate various magnetic fields like dipole, quadrupole, and sextupole are derived. Using the 2D result as a starting point, a computer code is developed to get the optimum orientation of the magnets to obtain the user-specific target field profile over a given volume in 3D. Designs of two quadrupole magnets are presented, one using 12 and the other using 24 permanent-magnet blocks. Variation of the quadrupole strength is achieved using tuning coils of a suitable current density and specially designed end tubes. A new concept is introduced to reduce the integrated quadrupole field strength by inserting two hollow cylindrical tubes made of iron, one at each end. This will not affect the field gradient at the center but reduce the integrated field strength by shielding the magnetic field near the ends where the tubes are inserted. The advantages of this scheme are that it is easy to implement, the magnetic axis will not shift, and it will prevent interference with nearby devices. Around 40% integrated field variation is achieved using this method in the present example. To get a realistic estimation of the field quality, a complete 3D model using a nonlinear B -H curve is also studied using a finite-element-based computer code. An example to generate around an 80 T /m quadrupole field gradient is also presented.

Factors Influencing Singapore Students' Choice of Physics as a Tertiary Field of Study: A Rasch Analysis

ERIC Educational Resources Information Center

Oon, Pey-Tee; Subramaniam, R.

2013-01-01

Asian students often perform well in international science and mathematics assessments. Their attitude toward technical subjects, such as physics, remains curious for many. The present study examines Singapore school students' views on various aspects of physics according to whether they intend to choose physics as an advanced field of study. A…

Linking state regulation, brain laterality, and self-reported attention-deficit/hyperactivity disorder (ADHD) symptoms in adults.

PubMed

Mohamed, Saleh M H; Börger, Norbert A; Geuze, Reint H; van der Meere, Jaap J

2016-10-01

Many clinical studies have shown that performance of subjects with attention-deficit/hyperactivity disorder (ADHD) is impaired when stimuli are presented at a slow rate compared to a medium or fast rate. According to the cognitive-energetic model, this finding may reflect difficulty in allocating sufficient effort to regulate the motor activation state. Other studies have shown that the left hemisphere is relatively responsible for keeping humans motivated, allocating sufficient effort to complete their tasks. This leads to a prediction that poor effort allocation might be associated with an affected left-hemisphere functioning in ADHD. So far, this prediction has not been directly tested, which is the aim of the present study. Seventy-seven adults with various scores on the Conners' Adult ADHD Rating Scale performed a lateralized lexical decision task in three conditions with stimuli presented in a fast, a medium, and a slow rate. The left-hemisphere functioning was measured in terms of visual field advantage (better performance for the right than for the left visual field). All subjects showed an increased right visual field advantage for word processing in the slow presentation rate of stimuli compared to the fast and the medium rate. Higher ADHD scores were related to a reduced right visual field advantage in the slow rate only. The present findings suggest that ADHD symptomatology is associated with less involvement of the left hemisphere when extra effort allocation is needed to optimize the low motor activation state.

Charged Compact Boson Stars in a Theory of Massless Scalar Field

NASA Astrophysics Data System (ADS)

Kumar, Sanjeev

2018-05-01

In this work we present some new results obtained in a study of the phase diagram of charged compact boson stars in a theory involving a complex scalar field with a conical potential coupled to a U(1) gauge field and gravity. We obtain new bifurcation points in this model. We present a detailed discussion of the various regions of the phase diagram with respect to the bifurcation points. The theory is seen to contain rich physics in a particular domain of the phase diagram.

Evidence of Magnetic Breakdown on the Defects With Thermally Suppressed Critical Field in High Gradient SRF Cavities

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

Eremeev, Grigory; Palczewski, Ari

2013-09-01

At SRF 2011 we presented the study of quenches in high gradient SRF cavities with dual mode excitation technique. The data differed from measurements done in 80's that indicated thermal breakdown nature of quenches in SRF cavities. In this contribution we present analysis of the data that indicates that our recent data for high gradient quenches is consistent with the magnetic breakdown on the defects with thermally suppressed critical field. From the parametric fits derived within the model we estimate the critical breakdown fields.

Entanglement of a quantum field with a dispersive medium.

PubMed

Klich, Israel

2012-08-10

In this Letter we study the entanglement of a quantum radiation field interacting with a dielectric medium. In particular, we describe the quantum mixed state of a field interacting with a dielectric through plasma and Drude models and show that these generate very different entanglement behavior, as manifested in the entanglement entropy of the field. We also present a formula for a "Casimir" entanglement entropy, i.e., the distance dependence of the field entropy. Finally, we study a toy model of the interaction between two plates. In this model, the field entanglement entropy is divergent; however, as in the Casimir effect, its distance-dependent part is finite, and the field matter entanglement is reduced when the objects are far.

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.

Defining the Field: Revisiting the ACA 1995 Definition of Communication Studies.

ERIC Educational Resources Information Center

Korn, Charles J.; Morreale, Sherwyn P.; Boileau, Don M.

2000-01-01

Presents results of a survey of Association for Communication Administration (ACA) members concerning their awareness and use of the 1995 ACA Definition of the Field of Communication. Finds that 40% of administrators who responded were unaware of the definition. Urges the need to further promote the definition of the field. (NH)

Concerns of Teacher Candidates in an Early Field Experience

ERIC Educational Resources Information Center

Chang, Sau Hou

2009-01-01

The present study examined the concerns of teacher candidates in an early field experience. Thirty-five teacher candidates completed the Teacher Concerns Checklist (TCC, Fuller & Borich, 2000) at the beginning, middle and end of their early field experiences. Results showed that teacher candidates ranked impact as the highest concern, self as…

Reflections on Teaching and Learning for Sustainability from the Cascadia Sustainability Field School

ERIC Educational Resources Information Center

Owens, Cameron; Sotoudehnia, Maral; Erickson-McGee, Paige

2015-01-01

A complex and contested concept, sustainability presents a great challenge to teachers and learners. Field study is a potentially promising venue to unpack the problematics of sustainability in practice. This paper reflects on the Cascadia Sustainability Field School, offered through the University of Victoria, Canada, providing an overview of the…

Educated Mis-Employment in Hong Kong: Earnings Effects of Employment in Unmatched Fields of Work.

ERIC Educational Resources Information Center

Chung, Yue-Ping

1990-01-01

Presents an empirical study on misemployment (the underutilization of worker's skills acquired through vocational education) in Hong Kong. Analyzes earnings functions of graduates from various educational fields and for workers employed in various fields. Misemployed graduates received lower earnings than their colleagues working in matched work…

Visual Field Asymmetry in Attentional Capture

ERIC Educational Resources Information Center

Du, Feng; Abrams, Richard A.

2010-01-01

The present study examined the spatial distribution of involuntary attentional capture over the two visual hemi-fields. A new experiment, and an analysis of three previous experiments showed that distractors in the left visual field that matched a sought-for target in color produced a much larger capture effect than identical distractors in the…

LABORATORY AND FIELD STUDIES TO EVALUATE RISKS TO LARVAL FISH FROM PHOTO-ACTIVATED TOXICITY OF PAHS

EPA Science Inventory

Hazard from photo-activation of PAHs has been well documented in aquatic organisms. Far less certain is the degree to which risk actually occurs in the field. This presentation outlines a series of laboratory and field experiments conducted to better understand the dosimetry and ...

High-frequency analysis of Earth gravity field models based on terrestrial gravity and GPS/levelling data: a case study in Greece

NASA Astrophysics Data System (ADS)

Papanikolaou, T. D.; Papadopoulos, N.

2015-06-01

The present study aims at the validation of global gravity field models through numerical investigation in gravity field functionals based on spherical harmonic synthesis of the geopotential models and the analysis of terrestrial data. We examine gravity models produced according to the latest approaches for gravity field recovery based on the principles of the Gravity field and steadystate Ocean Circulation Explorer (GOCE) and Gravity Recovery And Climate Experiment (GRACE) satellite missions. Furthermore, we evaluate the overall spectrum of the ultra-high degree combined gravity models EGM2008 and EIGEN-6C3stat. The terrestrial data consist of gravity and collocated GPS/levelling data in the overall Hellenic region. The software presented here implements the algorithm of spherical harmonic synthesis in a degree-wise cumulative sense. This approach may quantify the bandlimited performance of the individual models by monitoring the degree-wise computed functionals against the terrestrial data. The degree-wise analysis performed yields insight in the short-wavelengths of the Earth gravity field as these are expressed by the high degree harmonics.

Interplanetary field and plasma during initial phase of geomagnetic storms

NASA Technical Reports Server (NTRS)

Patel, V. L.; Wiskerchen, M. J.

1975-01-01

A study has been conducted of a large number of geomagnetic storms occurring during the period from 1966 to 1970. Questions of data selection are discussed and the large-scale interplanetary magnetic field during the initial phase is examined. Small-scale interplanetary fields during the initial phase are also considered, taking into account important features of small-scale variations in the interplanetary field and plasma for three storms. Details concerning 23 geomagnetic storms and the interplanetary magnetic field are presented in a table. A study of the initial phase of these storms indicates that in most of these events, the solar-ecliptic Z component of the interplanetary magnetic field turns southward when the main phase decrease begins.

Behavioral evidence for inter-hemispheric cooperation during a lexical decision task: a divided visual field experiment.

PubMed

Perrone-Bertolotti, Marcela; Lemonnier, Sophie; Baciu, Monica

2013-01-01

HIGHLIGHTSThe redundant bilateral visual presentation of verbal stimuli decreases asymmetry and increases the cooperation between the two hemispheres.The increased cooperation between the hemispheres is related to semantic information during lexical processing.The inter-hemispheric interaction is represented by both inhibition and cooperation. This study explores inter-hemispheric interaction (IHI) during a lexical decision task by using a behavioral approach, the bilateral presentation of stimuli within a divided visual field experiment. Previous studies have shown that compared to unilateral presentation, the bilateral redundant (BR) presentation decreases the inter-hemispheric asymmetry and facilitates the cooperation between hemispheres. However, it is still poorly understood which type of information facilitates this cooperation. In the present study, verbal stimuli were presented unilaterally (left or right visual hemi-field successively) and bilaterally (left and right visual hemi-field simultaneously). Moreover, during the bilateral presentation of stimuli, we manipulated the relationship between target and distractors in order to specify the type of information which modulates the IHI. Thus, three types of information were manipulated: perceptual, semantic, and decisional, respectively named pre-lexical, lexical and post-lexical processing. Our results revealed left hemisphere (LH) lateralization during the lexical decision task. In terms of inter-hemisphere interaction, the perceptual and decision-making information increased the inter-hemispheric asymmetry, suggesting the inhibition of one hemisphere upon the other. In contrast, semantic information decreased the inter-hemispheric asymmetry, suggesting cooperation between the hemispheres. We discussed our results according to current models of IHI and concluded that cerebral hemispheres interact and communicate according to various excitatory and inhibitory mechanisms, all which depend on specific processes and various levels of word processing.

Behavioral evidence for inter-hemispheric cooperation during a lexical decision task: a divided visual field experiment

PubMed Central

Perrone-Bertolotti, Marcela; Lemonnier, Sophie; Baciu, Monica

2013-01-01

HIGHLIGHTS The redundant bilateral visual presentation of verbal stimuli decreases asymmetry and increases the cooperation between the two hemispheres.The increased cooperation between the hemispheres is related to semantic information during lexical processing.The inter-hemispheric interaction is represented by both inhibition and cooperation. This study explores inter-hemispheric interaction (IHI) during a lexical decision task by using a behavioral approach, the bilateral presentation of stimuli within a divided visual field experiment. Previous studies have shown that compared to unilateral presentation, the bilateral redundant (BR) presentation decreases the inter-hemispheric asymmetry and facilitates the cooperation between hemispheres. However, it is still poorly understood which type of information facilitates this cooperation. In the present study, verbal stimuli were presented unilaterally (left or right visual hemi-field successively) and bilaterally (left and right visual hemi-field simultaneously). Moreover, during the bilateral presentation of stimuli, we manipulated the relationship between target and distractors in order to specify the type of information which modulates the IHI. Thus, three types of information were manipulated: perceptual, semantic, and decisional, respectively named pre-lexical, lexical and post-lexical processing. Our results revealed left hemisphere (LH) lateralization during the lexical decision task. In terms of inter-hemisphere interaction, the perceptual and decision-making information increased the inter-hemispheric asymmetry, suggesting the inhibition of one hemisphere upon the other. In contrast, semantic information decreased the inter-hemispheric asymmetry, suggesting cooperation between the hemispheres. We discussed our results according to current models of IHI and concluded that cerebral hemispheres interact and communicate according to various excitatory and inhibitory mechanisms, all which depend on specific processes and various levels of word processing. PMID:23818879

The evolving magnetic topology of τ Boötis

NASA Astrophysics Data System (ADS)

Mengel, M. W.; Fares, R.; Marsden, S. C.; Carter, B. D.; Jeffers, S. V.; Petit, P.; Donati, J.-F.; Folsom, C. P.; BCool Collaboration

2016-07-01

We present six epochs of spectropolarimetric observations of the hot-Jupiter-hosting star τ Boötis that extend the exceptional previous multiyear data set of its large-scale magnetic field. Our results confirm that the large-scale magnetic field of τ Boötis varies cyclicly, with the observation of two further magnetic reversals; between 2013 December and 2014 May and between 2015 January and March. We also show that the field evolves in a broadly solar-type manner in contrast to other F-type stars. We further present new results which indicate that the chromospheric activity cycle and the magnetic activity cycles are related, which would indicate a very rapid magnetic cycle. As an exemplar of long-term magnetic field evolution, τ Boötis and this long-term monitoring campaign presents a unique opportunity for studying stellar magnetic cycles.

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

Huggins, A.W.

A field research effort was conducted in the vicinity of the Tushar Mountains of southern Utah as part of the Federal-State Program in Atmospheric Modification Research involving the National Oceanic and Atmospheric Administration and the State of Utah. The field study took place in February and March 1989 and emphasized the studies of supercooled liquid water evolution in winter storms and attempts to measure the effects of ground-based silver iodide cloud seeding. Results of the field effort are presented.

Electromagnon excitation in the field-induced nonlinear ferrimagnetic phase of Ba 2Mg 2Fe 12O 22 studied by polarized inelastic neutron and terahertz time-domain optical spectroscopy

DOE PAGES

Nakajima, Taro; Takahashi, Youtarou; Kibayashi, Shunsuke; ...

2016-01-19

We have studied magnetic excitations in a field-induced noncollinear commensurate ferrimagnetic phase of Ba 2Mg 2Fe 12O 22 by means of polarized inelastic neutron scattering (PINS) and terahertz (THz) time-domain optical spectroscopy under magnetic field. A previous THz spectroscopy study reported that the field-induced phase exhibits electric-dipole-active excitations with energies of around 5 meV [Kida et al., Phys. Rev. B 83, 064422 (2011)]. In the present PINS measurements, we observed inelastic scattering signals around 5 meV at the zone center in the spin-flip channel. This directly shows that the electric-dipole-active excitations are indeed of magnetic origin, that is, electromagnons. Inmore » addition, the present THz spectroscopy confirms that the excitations have oscillating electric polarization parallel to the c axis. In terms of the spin-current model (Katsura-Nagaosa-Balatsky model), the noncollinear magnetic order in the field-induced phase can induce static electric polarization perpendicular to the c axis, but not dynamic electric polarization along the c axis. Furthermore, we suggest that the electromagnon excitations can be explained by applying the magnetostriction model to the out-of-phase oscillations of the magnetic moments, which is deduced from the present experimental results.« less

Commercial D-T FRC Power Plant Systems Analysis

NASA Astrophysics Data System (ADS)

Nguyen, Canh; Santarius, John; Emmert, Gilbert; Steinhauer, Loren; Stubna, Michael

1998-11-01

Results of an engineering issues scoping study of a Field-Reversed Configuration (FRC) burning D-T fuel will be presented. The study primarily focuses on engineering issues, such as tritium-breeding blanket design, radiation shielding, neutron damage, activation, safety, and environment. This presentation will concentrate on plasma physics, current drive, economics, and systems integration, which are important for the overall systems analysis. A systems code serves as the key tool in defining a reference point for detailed physics and engineering calculations plus parametric variations, and typical cases will be presented. Advantages of the cylindrical geometry and high beta (plasma pressure/magnetic-field pressure) are evident.

Non-minimally coupled scalar field cosmology with torsion

NASA Astrophysics Data System (ADS)

Cid, Antonella; Izaurieta, Fernando; Leon, Genly; Medina, Perla; Narbona, Daniela

2018-04-01

In this work we present a generalized Brans-Dicke lagrangian including a non-minimally coupled Gauss-Bonnet term without imposing the vanishing torsion condition. In the resulting field equations, the torsion is closely related to the dynamics of the scalar field, i.e., if non-minimally coupled terms are present in the theory, then the torsion must be present. For the studied lagrangian we analyze the cosmological consequences of an effective torsional fluid and we show that this fluid can be responsible for the current acceleration of the universe. Finally, we perform a detailed dynamical system analysis to describe the qualitative features of the model, we find that accelerated stages are a generic feature of this scenario.

Parametrically Optimized Carbon Nanotube-Coated Cold Cathode Spindt Arrays

PubMed Central

Yuan, Xuesong; Cole, Matthew T.; Zhang, Yu; Wu, Jianqiang; Milne, William I.; Yan, Yang

2017-01-01

Here, we investigate, through parametrically optimized macroscale simulations, the field electron emission from arrays of carbon nanotube (CNT)-coated Spindts towards the development of an emerging class of novel vacuum electron devices. The present study builds on empirical data gleaned from our recent experimental findings on the room temperature electron emission from large area CNT electron sources. We determine the field emission current of the present microstructures directly using particle in cell (PIC) software and present a new CNT cold cathode array variant which has been geometrically optimized to provide maximal emission current density, with current densities of up to 11.5 A/cm2 at low operational electric fields of 5.0 V/μm. PMID:28336845

Microscopic observation of magnetic bacteria in the magnetic field of a rotating permanent magnet.

PubMed

Smid, Pieter; Shcherbakov, Valeriy; Petersen, Nikolai

2015-09-01

Magnetotactic bacteria are ubiquitous and can be found in both freshwater and marine environments. Due to intracellular chains of magnetic single domain particles, they behave like swimming compass needles. In external magnetic fields like the Earth's magnetic field, a torque is acting on the chain. This will cause the bacterium to be rotated and aligned with the external field. The swimming direction of magnetotactic bacteria can be controlled with external magnetic fields, which makes it convenient to study them under a light microscope. Usually, a special set of coils arranged around a light microscope is used to control the swimming magnetotactic bacteria. Here, we present a simple mechanical system with a permanent magnet, which produces a rotating magnetic field of nearly constant amplitude in the focal plane of a light microscope. The device is placed beside the light microscope and easily adaptable to almost any microscope and thus convenient for field experiments. To describe the trajectories qualitatively, a theoretical model of the trajectories is presented. This device can be used to control the swimming direction of magnetotactic bacteria and also for studying their magnetic and hydrodynamic properties.

Insight into the Li2CO3-K2CO3 eutectic mixture from classical molecular dynamics: Thermodynamics, structure, and dynamics

NASA Astrophysics Data System (ADS)

Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

2016-03-01

We use molecular dynamics simulations to study the thermodynamics, structure, and dynamics of the Li2CO3-K2CO3 (62:38 mol. %) eutectic mixture. We present a new classical non-polarizable force field for this molten salt mixture, optimized using experimental and first principles molecular dynamics simulations data as reference. This simple force field allows efficient molecular simulations of phenomena at long time scales. We use this optimized force field to describe the behavior of the eutectic mixture in the 900-1100 K temperature range, at pressures between 0 and 5 GPa. After studying the equation of state in these thermodynamic conditions, we present molecular insight into the structure and dynamics of the melt. In particular, we present an analysis of the temperature and pressure dependence of the eutectic mixture's self-diffusion coefficients, viscosity, and ionic conductivity.

Insight into the Li2CO3-K2CO3 eutectic mixture from classical molecular dynamics: Thermodynamics, structure, and dynamics.

PubMed

Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

2016-03-14

We use molecular dynamics simulations to study the thermodynamics, structure, and dynamics of the Li2CO3-K2CO3 (62:38 mol. %) eutectic mixture. We present a new classical non-polarizable force field for this molten salt mixture, optimized using experimental and first principles molecular dynamics simulations data as reference. This simple force field allows efficient molecular simulations of phenomena at long time scales. We use this optimized force field to describe the behavior of the eutectic mixture in the 900-1100 K temperature range, at pressures between 0 and 5 GPa. After studying the equation of state in these thermodynamic conditions, we present molecular insight into the structure and dynamics of the melt. In particular, we present an analysis of the temperature and pressure dependence of the eutectic mixture's self-diffusion coefficients, viscosity, and ionic conductivity.

Caffeine Improves Left Hemisphere Processing of Positive Words

PubMed Central

Kuchinke, Lars; Lux, Vanessa

2012-01-01

A positivity advantage is known in emotional word recognition in that positive words are consistently processed faster and with fewer errors compared to emotionally neutral words. A similar advantage is not evident for negative words. Results of divided visual field studies, where stimuli are presented in either the left or right visual field and are initially processed by the contra-lateral brain hemisphere, point to a specificity of the language-dominant left hemisphere. The present study examined this effect by showing that the intake of caffeine further enhanced the recognition performance of positive, but not negative or neutral stimuli compared to a placebo control group. Because this effect was only present in the right visual field/left hemisphere condition, and based on the close link between caffeine intake and dopaminergic transmission, this result points to a dopaminergic explanation of the positivity advantage in emotional word recognition. PMID:23144893

Algebraic Thinking in Solving Linier Program at High School Level: Female Student’s Field Independent Cognitive Style

NASA Astrophysics Data System (ADS)

Hardiani, N.; Budayasa, I. K.; Juniati, D.

2018-01-01

The aim of this study was to describe algebraic thinking of high school female student’s field independent cognitive style in solving linier program problem by revealing deeply the female students’ responses. Subjects in this study were 7 female students having field independent cognitive style in class 11. The type of this research was descriptive qualitative. The method of data collection used was observation, documentation, and interview. Data analysis technique was by reduction, presentation, and conclusion. The results of this study showed that the female students with field independent cognitive style in solving the linier program problem had the ability to represent algebraic ideas from the narrative question that had been read by manipulating symbols and variables presented in tabular form, creating and building mathematical models in two variables linear inequality system which represented algebraic ideas, and interpreting the solutions as variables obtained from the point of intersection in the solution area to obtain maximum benefit.

Understanding and manipulating the RF fields at high field MRI

PubMed Central

Ibrahim, Tamer S.; Hue, YiK-Kiong; Tang, Lin

2015-01-01

This paper presents a complete overview of the electromagnetics (radiofrequency aspect) of MRI at low and high fields. Using analytical formulations, numerical modeling (computational electromagnetics), and ultrahigh field imaging experiments, the physics that impacts the electromagnetic quantities associated with MRI, namely (1) the transmit field, (2) receive field, and (3) total electromagnetic power absorption, is analyzed. The physical interpretation of the above-mentioned quantities is investigated by electromagnetic theory, to understand ‘What happens, in terms of electromagnetics, when operating at different static field strengths?’ Using experimental studies and numerical simulations, this paper also examines the physical and technological feasibilities by which all or any of these specified electromagnetic quantities can be manipulated through techniques such as B1 shimming (phased array excitation) and signal combination using a receive array in order to advance MRI at high field strengths. Pertinent to this subject and with highly coupled coils operating at 7 T, this paper also presents the first phantom work on B1 shimming without B1 measurements. PMID:19621335

Lexical Decision with Left, Right and Center Visual Field Presentation: A Comparison between Dyslexic and Regular Readers by Means of Electrophysiological and Behavioral Measures

ERIC Educational Resources Information Center

Shaul, Shelley

2012-01-01

This study examined the differences in processing between regular and dyslexic readers in a lexical decision task in different visual field presentations (left, right, and center). The research utilized behavioral measures that provide information on accuracy and reaction time and electro-physiological measures that permit the examination of brain…

The interaction between the cognitive style of field dependence and visual presentations in color, monochrome, and line drawings

NASA Astrophysics Data System (ADS)

Myers, Robert Gardner

1997-12-01

The purpose of this study was to determine whether there is a correlation between the cognitive style of field dependence and the type of visual presentation format used in a computer-based tutorial (color; black and white: or line drawings) when subjects are asked to identify human tissue samples. Two hundred-four college students enrolled in human anatomy and physiology classes at Westmoreland County Community College participated. They were first administered the Group Embedded Figures Test (GEFT) and then were divided into three groups: field-independent (score, 15-18), field-neutral (score, 11-14), and field dependent (score, 0-10). Subjects were randomly assigned to one of the three treatment groups. Instruction was delivered by means of a computer-aided tutorial consisting of text and visuals of human tissue samples. The pretest and posttest consisted of 15 tissue samples, five from each treatment, that were imported into the HyperCardsp{TM} stack and were played using QuickTimesp{TM} movie extensions. A two-way analysis of covariance (ANCOVA) using pretest and posttest scores was used to investigate whether there is a relationship between field dependence and each of the three visual presentation formats. No significant interaction was found between individual subject's relative degree of field dependence and any of the different visual presentation formats used in the computer-aided tutorial module, F(4,194) = 1.78, p =.1335. There was a significant difference between the students' levels of field dependence in terms of their ability to identify human tissue samples, F(2,194) = 5.83, p =.0035. Field-independent subjects scored significantly higher (M = 10.59) on the posttest than subjects who were field-dependent (M = 9.04). There was also a significant difference among the various visual presentation formats, F(2,194) = 3.78, p =.0245. Subjects assigned to the group that received the color visual presentation format scored significantly higher (M = 10.38) on the posttest measure than did those assigned to the group that received the line drawing visual presentation format (8.99).

Field Ecology Studies in the Rocky Mountains.

ERIC Educational Resources Information Center

Robertson, Philip A.

1978-01-01

Describes a six-week field plant ecology course in Montana which is offered by the Botany Department at Southern Illinois University. The goals of the course, how it is taught, and student evaluation are also presented. (HM)

Neutral winds and electric fields from model studies using reduced ionograms

NASA Technical Reports Server (NTRS)

Baran, D. E.

1974-01-01

A relationship between the vertical component of the ion velocity and electron density profiles derived from reduced ionograms is developed. Methods for determining the horizontal components of the neutral winds and electric fields by using this relationship and making use of the variations of the inclinations and declinations of the earth's magnetic field are presented. The effects that electric fields have on the neutral wind calculations are estimated to be small but not second order. Seasonal and latitudinal variations of the calculated neutral winds are presented. From the calculated neutral winds a new set of neutral pressure gradients is determined. The new pressure gradients are compared with those generated from several static neutral atmospheric models. Sensitivity factors relating the pressure gradients and neutral winds are calculated and these indicate that mode coupling and harmonic generation are important to studies which assume linearized theories.

An investigation into possible quantum chaos in the H2 molecule under intense laser fields via Ehrenfest phase space (EPS) trajectories.

PubMed

Sadhukhan, Mainak; Deb, B M

2018-06-21

By employing the Ehrenfest "phase space" trajectory method for studying quantum chaos, developed in our laboratory, the present study reveals that the H 2 molecule under intense laser fields of three different intensities, I = 1 × 10 14  W/cm 2 , 5 × 10 14  W/cm 2 , and 1 × 10 15  W/cm 2 , does not show quantum chaos. A similar conclusion is also reached through the Loschmidt echo (also called quantum fidelity) calculations reported here for the first time for a real molecule under intense laser fields. Thus, a long-standing conjecture about the possible existence of quantum chaos in atoms and molecules under intense laser fields has finally been tested and not found to be valid in the present case.

Broadband near-field mid-infrared spectroscopy and application to phonon resonances in quartz.

PubMed

Ishikawa, Michio; Katsura, Makoto; Nakashima, Satoru; Ikemoto, Yuka; Okamura, Hidekazu

2012-05-07

Infrared (IR) spectroscopy is a versatile analytical method and nano-scale spatial resolution could be achieved by scattering type near-field optical microscopy (s-SNOM). The spectral bandwidth was, however, limited to approximately 300 cm(-1) with a laser light source. In the present study, the development of a broadband mid-IR near-field spectroscopy with a ceramic light source is demonstrated. A much wider bandwidth (at least 3000 to 1000 cm(-1)) is achieved with a ceramic light source. The experimental data on quartz Si-O phonon resonance bands are well reproduced by theoretical simulations indicating the validity of the present broadband near-field IR spectroscopy.

Experimental and Numerical Study of Drift Alfv'en Waves in LAPD

NASA Astrophysics Data System (ADS)

Friedman, Brett; Popovich, P.; Carter, T. A.; Auerbach, D.; Schaffner, D.

2009-11-01

We present a study of drift Alfv'en waves in linear geometry using experiments in the Large Plasma Device (LAPD) at UCLA and simulations from the Boundary Turbulence code (BOUT). BOUT solves the 3D time evolution of plasma parameters and turbulence using Braginskii fluid equations. First, we present a verification study of linear drift Alfven wave physics in BOUT, which has been modified to simulate the cylindrical geometry of LAPD. Second, we present measurements of density and magnetic field fluctuations in the LAPD plasma and the correlation of these fluctuations as a function of plasma parameters, including strength of the background field and discharge current. We also compare the measurements to nonlinear BOUT calculations using experimental LAPD profiles.

High-yield, ultrafast, surface plasmon-enhanced, Au nanorod optical field electron emitter arrays.

PubMed

Hobbs, Richard G; Yang, Yujia; Fallahi, Arya; Keathley, Philip D; De Leo, Eva; Kärtner, Franz X; Graves, William S; Berggren, Karl K

2014-11-25

Here we demonstrate the design, fabrication, and characterization of ultrafast, surface-plasmon enhanced Au nanorod optical field emitter arrays. We present a quantitative study of electron emission from Au nanorod arrays fabricated by high-resolution electron-beam lithography and excited by 35 fs pulses of 800 nm light. We present accurate models for both the optical field enhancement of Au nanorods within high-density arrays, and electron emission from those nanorods. We have also studied the effects of surface plasmon damping induced by metallic interface layers at the substrate/nanorod interface on near-field enhancement and electron emission. We have identified the peak optical field at which the electron emission mechanism transitions from a 3-photon absorption mechanism to strong-field tunneling emission. Moreover, we have investigated the effects of nanorod array density on nanorod charge yield, including measurement of space-charge effects. The Au nanorod photocathodes presented in this work display 100-1000 times higher conversion efficiency relative to previously reported UV triggered emission from planar Au photocathodes. Consequently, the Au nanorod arrays triggered by ultrafast pulses of 800 nm light in this work may outperform equivalent UV-triggered Au photocathodes, while also offering nanostructuring of the electron pulse produced from such a cathode, which is of interest for X-ray free-electron laser (XFEL) development where nanostructured electron pulses may facilitate more efficient and brighter XFEL radiation.

Angular Distribution of Hyperfine Magnetic Field in Fe3O4 and Fe66Ni34 from Mössbauer Polarimetry

NASA Astrophysics Data System (ADS)

Szymański, K.; Satuła, D.; Dobrzyński, L.

2004-12-01

Experimental determination of some angular averages of hyperfine field is demonstrated. The averages relates to magnetic structure. Exemplary results of the measurements for Fe3O4 and Fe66Ni34 show that it is possible to obtain valuable information about the field magnitudes and orientations even when distributions of fields are present in the system under study.

Permanent magnets composed of high temperature superconductors

NASA Technical Reports Server (NTRS)

Weinstein, Roy; Chen, In-Gann; Liu, Jay; Lau, Kwong

1991-01-01

A study of persistent, trapped magnetic field has been pursued with high-temperature superconducting (HTS) materials. The main effort is to study the feasibility of utilization of HTS to fabricate magnets for various devices. The trapped field, when not in saturation, is proportional to the applied field. Thus, it should be possible to replicate complicated field configurations with melt-textured YBa2Cu3O7 (MT-Y123) material, bypassing the need for HTS wires. Presently, materials have been developed from which magnets of 1.5 T, at 77 K, can be fabricated. Much higher field is available at lower operating temperature. Stability of a few percent per year is readily attainable. Results of studies on prototype motors and minimagnets are reported.

The Sensorimotor System Can Sculpt Behaviorally Relevant Representations for Motor Learning

PubMed Central

2016-01-01

Abstract The coordinate system in which humans learn novel motor skills is controversial. The representation of sensorimotor skills has been extensively studied by examining generalization after learning perturbations specifically designed to be ambiguous as to their coordinate system. Recent studies have found that learning is not represented in any simple coordinate system and can potentially be accounted for by a mixed representation. Here, instead of probing generalization, which has led to conflicting results, we examine whether novel dynamics can be learned when explicitly and unambiguously presented in particular coordinate systems. Subjects performed center–out reaches to targets in the presence of a force field, while varying the orientation of their hand (i.e., the wrist angle) across trials. Different groups of subjects experienced force fields that were explicitly presented either in Cartesian coordinates (field independent of hand orientation), in object coordinates (field rotated with hand orientation), or in anti-object coordinates (field rotated counter to hand orientation). Subjects learned to represent the dynamics when presented in either Cartesian or object coordinates, learning these as well as an ambiguous force field. However, learning was slower for the object-based dynamics and substantially impaired for the anti-object presentation. Our results show that the motor system is able to tune its representation to at least two natural coordinate systems but is impaired when the representation of the task does not correspond to a behaviorally relevant coordinate system. Our results show that the motor system can sculpt its representation through experience to match those of natural tasks. PMID:27588304

Evaluation of peripheral binocular visual field in patients with glaucoma: a pilot study.

PubMed

Ana, Banc; Cristina, Stan; Dorin, Chiselita

2016-01-01

The objective of this study was to evaluate the peripheral binocular visual field (PBVF) in patients with glaucoma using the threshold strategy of Humphrey Field Analyzer. We conducted a case-control pilot study in which we enrolled 59 patients with glaucoma and 20 controls. All participants were evaluated using a custom PBVF test and central 24 degrees monocular visual field tests for each eye using the threshold strategy. The central binocular visual field (CBVF) was predicted from the monocular tests using the most sensitive point at each field location. The glaucoma patients were grouped according to Hodapp classification and age. The PBVF was compared to controls and the relationship between the PBVF and CBVF was tested. The areas of frame-induced artefacts were determined (over 50 degrees in each temporal field, 24 degrees superiorly and 45 degrees inferiorly) and excluded from interpretation. The patients presented a statistically significant generalized decrease of the peripheral retinal sensitivity compared to controls for Hodapp initial stage--groups aged 50-59 (t = 11.93 > 2.06; p < 0.05) and 60-69 (t = 7.55 > 2.06; p < 0.05). For the initial Hodapp stage there was no significant relationship between PBVF and CBVF (r = 0.39). For the moderate and advanced Hodapp stages, the interpretation of data was done separately for each patient. This pilot study suggests that glaucoma patients present a decrease of PBVF compared to controls and CBVF cannot predict the PBVF in glaucoma.

Field size, length, and width distributions based on LACIE ground truth data. [large area crop inventory experiment

NASA Technical Reports Server (NTRS)

Pitts, D. E.; Badhwar, G.

1980-01-01

The development of agricultural remote sensing systems requires knowledge of agricultural field size distributions so that the sensors, sampling frames, image interpretation schemes, registration systems, and classification systems can be properly designed. Malila et al. (1976) studied the field size distribution for wheat and all other crops in two Kansas LACIE (Large Area Crop Inventory Experiment) intensive test sites using ground observations of the crops and measurements of their field areas based on current year rectified aerial photomaps. The field area and size distributions reported in the present investigation are derived from a representative subset of a stratified random sample of LACIE sample segments. In contrast to previous work, the obtained results indicate that most field-size distributions are not log-normally distributed. The most common field size observed in this study was 10 acres for most crops studied.

Functional Measurement in the Field of Empirical Bioethics

ERIC Educational Resources Information Center

Mullet, Etienne; Sorum, Paul C.; Teysseire, Nathalie; Nann, Stephanie; Martinez, Guadalupe Elizabeth Morales; Ahmed, Ramadan; Kamble, Shanmukh; Olivari, Cecilia; Sastre, Maria Teresa Munoz

2012-01-01

We present, in a synthetic way, some of the main findings from five studies that were conducted in the field of empirical bioethics, using the Functional Measurement framework. These studies were about (a) the rationing of rare treatments, (b) adolescents' abortions, (c) end-of-life decision-making regarding damaged neonates, (d) end-of-life…

Upward Transfer in STEM Fields of Study: A New Conceptual Framework and Survey Instrument for Institutional Research

ERIC Educational Resources Information Center

Wang, Xueli

2016-01-01

This chapter describes a new conceptual framework that informs research on factors influencing transfer in STEM fields of study from 2-year to 4-year institutions, presents a new survey instrument based on the framework, and offers directions for future research in this area.

Economic Development Threatens Groundwater in Puerto Rico: Results of a Field Study.

ERIC Educational Resources Information Center

Arbona, Sonia I.; Hunter, John M.

1995-01-01

Presents the results of a field study done on 7 wells providing 37% of the total aquifer production for 4 municipalities in Puerto Rico. Each sampled well showed signs of contamination by heavy metals, nitrate, and semivolatile organic compounds. Although found in low concentrations, current development threatens groundwater quality. (MJP)

Environmental Education and Field Studies Programs in Three Selected N. W. European Areas.

ERIC Educational Resources Information Center

VandenHazel, B. J.

Describing information gathered from a three-week (1976) tour of environmental education field studies programs in faculties of education and teachers' colleges located in the United Kingdom, the Netherlands, and Western Germany, this report presents comparative program and text summaries and recommends procedures for the Ontario Ministry of…

Interorganizational Special Education Programming in Rural Areas: Technical Report on the Multisite Naturalistic Field Study. Volumes I through IV.

ERIC Educational Resources Information Center

Skrtic, Thomas M.; And Others

The report discusses a field study of the implementation of major requirements of P.L. 94-142, the Education For All Handicapped Children Act, by rural districts, and presents detailed case studies of five districts' responses. The first volume introduces the naturalistic model of inquiry, noting its philosophical underpinnings and basic…

Cosmic Magnetic Fields

NASA Astrophysics Data System (ADS)

Sánchez Almeida, J.; Martínez González, M. J.

2018-05-01

Magnetic fields play an important role in many astrophysical processes. They are difficult to detect and characterize since often their properties have to be inferred through interpreting the polarization of the light. Magnetic fields are also challenging to model and understand. Magnetized plasmas behave following highly non-linear differential equations having no general solution, so that every astrophysical problem represents a special case to be studied independently. Hence, magnetic fields are often an inconvenient subject which is overlooked or simply neglected (the elephant in the room, as they are dubbed in poster of the school). Such difficulty burdens the research on magnetic fields, which has evolved to become a very technical subject, with many small disconnected communities studying specific aspects and details. The school tried to amend the situation by providing a unifying view of the subject. The students had a chance to understand the behavior of magnetic fields in all astrophysical contexts, from cosmology to the Sun, and from starbursts to AGNs. The school was planed to present a balanced yet complete review of our knowledge, with excursions into the unknown to point out present and future lines of research. The subject of Cosmic Magnetic Fields was split into seven different topics: cosmic magnetic field essentials, solar magnetic fields, stellar magnetic fields, the role of magnetic fields on AGN feedback, magnetic fields in galaxies, magnetic fields in galaxy clusters and at larger scales, and primordial magnetic fields and magnetic fields in the early Universe. The corresponding lectures were delivered by seven well known and experienced scientists that have played key roles in the major advances of the field during the last years: F. Cattaneo, P. Judge, O. Kochukhov, R. Keppens, R. Beck, K. Dolag, and F. Finelli. Their lectures were recorded and are freely available at the IAC website: http://iactalks.iac.es/talks/serie/19.

Towards more Global Coordination of Atmospheric Electricity Measurements (GloCAEM)

NASA Astrophysics Data System (ADS)

Nicoll, Keri; Harrison, Giles

2017-04-01

Earth's atmospheric electrical environment has been studied since the 1750s but its more recent applications to science questions around clouds and climate highlight the incompleteness of our understanding, in part due to lack of suitable global measurements. The Global Electric Circuit (GEC) sustains the near-surface fair weather (FW) electric field, which is present globally in regions which are not strongly electrically disturbed by weather or pollution. It can be measured routinely at the surface using well established instrumentation such as electric field mills. Despite the central role of lightning as a weather hazard and the potentially widespread importance of charge for atmospheric processes, research is hampered by the fragmented nature of surface atmospheric electricity measurements. This makes anything other than local studies in fortuitous fair weather conditions difficult. In contrast to detection of global lightning using satellite measurements and ground-based radio networks, the FW electric field and GEC cannot be measured by remote sensing and no similar measurement networks exist for its study. This presents an opportunity as many researchers worldwide now make high temporal resolution measurements of the FW electric field routinely, which is neither coordinated nor exploited. The GLOCAEM (Global Coordination of Atmospheric Electricity Measurements) project is currently bringing some of these experts together to make the first steps towards an effective global network for FW atmospheric electricity monitoring. A specific objective of the project is to establish the first modern archive of international FW atmospheric electric field data in close to real time to allow global studies of atmospheric electricity to be straightforwardly and robustly performed. Data will be archived through the UK Centre for Environmental Data Analysis (CEDA) and will be available for download by users from early 2018. Both 1 second and 1 minute electric field data will be archived, along with meteorological measurements (if available) for ease of interpretation of electrical measurements. Although the primary aim of the project is to provide a close to real time electric field database, archiving of existing historical electric field datasets is also planned to extend the range of studies possible. This presentation will provide a summary of progress with the GLOCAEM project.

The calculation of force-free fields from discrete flux distributions. [for chromospheric magnetic fields

NASA Technical Reports Server (NTRS)

Sheeley, N. R., Jr.; Harvey, J. W.

1975-01-01

This paper presents particularly simple mathematical formulas for the calculation of force-free fields of constant alpha from the distribution of discrete sources on a flat surface. The advantage of these formulas lies in their physical simplicity and the fact that they can be easily used in practice to calculate the fields. The disadvantage is that they are limited to fields of 'sufficiently small alpha'. These formulas may be useful in the study of chromospheric magnetic fields by the comparison of high-resolution H-alpha photographs and photospheric magnetograms.

A Physiological and Biochemical Study of the Effects of Extremely Low Frequency Electromagnetic Fields

DTIC Science & Technology

1979-07-01

microplasmodial cultures continuously subjected to the particular field conditions being studied. The stages in ’ ,oitotic cycle ,re determined by observing...of the decrease in rate varies with exposure conditions . Mean values of the decreases computed from the raw data are given on the righthand side of...exposures we were concerned about was the effect of long-term, chronic exposure. Figure 2 presents data for field conditions that are the same as

Above Ground Field Evaluation and GC-MS Analysis of Naturally Durable Wood Species

Treesearch

G.T. Kirker; A.B. Blodgett; S.T. Lebow; C.A. Clausen

2012-01-01

Nine wood species are being evaluated in above ground field studies in Mississippi and Wisconsin. Candidate naturally durable wood (NDW) species are being rated at yearly intervals for resistance to decay, cupping, and checking. Field ratings after 12 months exposure are presented. To date, Paulownia tomentosa (PAW) and southern yellow pine (SYP)...

Lee side flow for slender delta wings of finite thickness

NASA Technical Reports Server (NTRS)

Szodruch, J. G.

1980-01-01

An experimental and theoretical investigation carried out to determine the lee side flow field over delta wings at supersonic speeds is presented. A theoretical method to described the flow field is described, where boundary conditions as a result of the experimental study are needed. The computed flow field with shock induced separation is satisfactory.

Effect of the magnetic field on coexisting stimulated Raman and Brillouin backscattering of an extraordinary mode

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

Vyas, Ashish, E-mail: ashishvyas.optics@gmail.com; Singh, Ram Kishor, E-mail: ram007kishor@gmail.com; Sharma, R. P., E-mail: rpsharma@ces.iitd.ernet.in

2016-01-15

This paper presents a model to study the interplay between the stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) in the presence of background magnetic field. This formalism is applicable to laser produced plasma as well as to heating mechanism in toroidal system by an extraordinary electromagnetic wave. In the former case, the magnetic field is self-generated, while in the latter case (toroidal plasmas) magnetic field is applied externally. The behavior of one scattering process is explicitly dependent on the coexisting scattering process as well as on the magnetic field. Explicit expressions for the back-reflectivity of scattered beams (SRSmore » and SBS) are presented. It has been demonstrated that due to the magnetic field and coexistence of the scattering processes (SRS and SBS) the back-reflectivity gets modified significantly. Results are also compared with the three wave interaction case (isolated SRS or SBS case)« less

A few categories of electromagnetic field problems treated through Fuzzy Logic

NASA Astrophysics Data System (ADS)

Lolea, M. S.; Dzitac, S.

2018-01-01

The paper deals with the problems of fuzzy logic applied in the field of electromagnetism. In the first part, there are presented some theoretical aspects regarding the characteristics and the application of the fuzzy logic in the general case. Are presented then, some categories of electromagnetic field problems treated by fuzzy logic. The accent is on the effects of exposure to the electromagnetic field on the human body. For this approach is dedicated a paragraph at the end of the paper. There is an application on how to treat by fuzzy logic the effects of electric field exposure. For this purpose, the fuzzy toolbox existing in the Matlab software and the results of some electric field strength measurements into a power substation are used. The results of the study and its conclusions are analyzed and exposed at the end of the paper.

Simulation study of the ionizing front in the critical ionization velocity phenomenon

NASA Technical Reports Server (NTRS)

Machida, S.; Goertz, C. K.; Lu, G.

1988-01-01

The simulation of the critical ionization velocity for a neutral gas cloud moving across the static magnetic field is presented. A low-beta plasma is studied, using a two and a half-dimensional electrostatic code linked with the Plasma and Neutral Interaction Code (Goertz and Machida, 1987). The physics of the ionizing front and the instabilities which occur there are discussed. Results are presented from four numerical runs designed so that the effects of the charge separation field can be distinguished from the wave heating.

Proactive interference of open field on consummatory successive negative contrast.

PubMed

Justel, Nadia; Pautassi, Ricardo; Mustaca, Alba

2014-03-01

Reactivity to a reward is affected by prior experience with the different reinforcer values of that reward, a phenomenon known as incentive relativity, which can be studied using the consummatory succesive negative contrast (cSNC) paradigm, in which the performance of animals that receive a 4 % sucrose solution after trials on which they were exposed to 32 % sucrose is compared with that of subjects that always receive the 4 % sucrose solution. The exploration of a novel open field can enhance or block the acquisition of associative and nonassociative memories. The effect of open field on cSNC has not yet been explored. The main result of the present study was that open-field exposure significantly modified the expression of cSNC. Exposure to an open field 1 h but not immediately before the downshift interfered with the expression of cSNC. These animals drank more of the downshifted reward than did controls that were not exposed to the apparatus, and this behavior persisted for up to three recovery trials. This phenomenon was observed even when the animals were given a more protracted preshift phase and when the discrepancy between the preshift and shift incentive values of sucrose were increased. An open field also interfered with incentive downshift when open-field exposure occurred 6 h before the downshift, and repeated exposure to the apparatus did not deteriorate this effect. The present study adds to a growing body of literature that indicates that open-field exploration can interfere with memory formation.

Ultra-wide-field imaging in diabetic retinopathy; an overview.

PubMed

Ghasemi Falavarjani, Khalil; Wang, Kang; Khadamy, Joobin; Sadda, Srinivas R

2016-06-01

To present an overview on ultra-wide-field imaging in diabetic retinopathy. A comprehensive search of the pubmed database was performed using the search terms of "ultra-wide-field imaging", "ultra-wide-field fluorescein angiography" and "diabetic retinopathy". The relevant original articles were reviewed. New advances in ultra-wide-field imaging allow for precise measurements of the peripheral retinal lesions. A consistent finding amongst these articles was that ultra-wide-field imaging improved detection of peripheral lesion. There was discordance among the studies, however, on the correlation between peripheral diabetic lesions and diabetic macular edema. Visualization of the peripheral retina using ultra-wide-field imaging improves diagnosis and classification of diabetic retinopathy. Additional studies are needed to better define the association of peripheral diabetic lesions with diabetic macular edema.

Use of LEED, Auger emission spectroscopy and field ion microscopy in microstructural studies

NASA Technical Reports Server (NTRS)

Ferrante, J.; Buckley, D. H.; Pepper, S. V.; Brainard, W. A.

1972-01-01

Surface research tools such as LEED, Auger emission spectroscopy analysis, and field ion microscopy are discussed. Examples of their use in studying adhesion, friction, wear, and lubrication presented. These tools have provided considerable insight into the basic nature of solid surface interactions. The transfer of metals from one surface to another at the atomic level has been observed and studied with each of these devices. The field ion microscope has been used to study polymer-metal interactions and Auger analysis to study the mechanism of polymer adhesion to metals. LEED and Auger analysis have identified surface segregation of alloying elements and indicated the influence of these elements in metallic adhesion. LEED and Auger analysis have assisted in adsorption studies in determining the structural arrangement and quantity of adsorbed species present in making an understanding of the influence of these species on adhesion possible. These devices are assisting in the furtherance of understanding of the fundamental mechanism involved in the adhesion, friction, wear, and lubrication processes.

CHARMM additive and polarizable force fields for biophysics and computer-aided drug design

PubMed Central

Vanommeslaeghe, K.

2014-01-01

Background Molecular Mechanics (MM) is the method of choice for computational studies of biomolecular systems owing to its modest computational cost, which makes it possible to routinely perform molecular dynamics (MD) simulations on chemical systems of biophysical and biomedical relevance. Scope of Review As one of the main factors limiting the accuracy of MD results is the empirical force field used, the present paper offers a review of recent developments in the CHARMM additive force field, one of the most popular bimolecular force fields. Additionally, we present a detailed discussion of the CHARMM Drude polarizable force field, anticipating a growth in the importance and utilization of polarizable force fields in the near future. Throughout the discussion emphasis is placed on the force fields’ parametrization philosophy and methodology. Major Conclusions Recent improvements in the CHARMM additive force field are mostly related to newly found weaknesses in the previous generation of additive force fields. Beyond the additive approximation is the newly available CHARMM Drude polarizable force field, which allows for MD simulations of up to 1 microsecond on proteins, DNA, lipids and carbohydrates. General Significance Addressing the limitations ensures the reliability of the new CHARMM36 additive force field for the types of calculations that are presently coming into routine computational reach while the availability of the Drude polarizable force fields offers a model that is an inherently more accurate model of the underlying physical forces driving macromolecular structures and dynamics. PMID:25149274

Field study of a pedestrian bridge of reinforced plastic.

DOT National Transportation Integrated Search

1985-01-01

A discussion of the behavior of the superstructure of a pedestrian bridge fabricated with glass-reinforced plastic under a field load test is presented. Experimental measurements of elastic vertical deflections were 1.8 times greater than those predi...

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

None

Brief summaries are presented of research in progress in the fields of radiobiology, genetics, hematology, immunology physiology. biochemistry, bacteriology, enzymology, microbiology, photosynthesis, biophysics, radiation protection, and related fields. A list is included of 240 publications in the world literature that report results of completed studies. (CH)

Cross-Field Comparison of Ethics Education: Golden Rules and Particulars.

PubMed

Mulhearn, Tyler J; Watts, Logan L; Torrence, Brett S; Todd, E Michelle; Turner, Megan R; Connelly, Shane; Mumford, Michael D

2017-01-01

Research misconduct negatively impacts the scientific community and society in general. Providing training in the responsible conduct of research (RCR) to researchers is one viable approach to minimizing research misconduct. Although recent evidence suggests ethics training can indeed be effective, little empirical work has examined the similarities and differences across fields. In the present study, we analyzed 62 empirical studies in engineering, biomedical science, social science, and mixed fields. The findings suggest certain instructional principles, or "golden rules," apply generally to all fields. These golden rules include maintaining a field-specific or field-general approach and emphasizing processes in training. The findings also suggest that content areas contributing to instructional effectiveness vary as a function of field. Generally, it appears that all fields may benefit from taking a multi-pronged approach to ethics education wherein the salient field issues are covered. Implications for RCR education are discussed.

Early results from Magsat. [studies of near-earth magnetic fields

NASA Technical Reports Server (NTRS)

Langel, R. A.; Estes, R. H.; Mayhew, M. A.

1981-01-01

Papers presented at the May 27, 1981 meeting of the American Geophysical Union concerning early results from the Magsat satellite program, which was designed to study the near-earth magnetic fields originating in the core and lithosphere, are discussed. The satellite was launched on October 30, 1979 into a sun-synchronous (twilight) orbit, and re-entered the atmosphere on June 11, 1980. Instruments carried included a cesium vapor magnetometer to measure field magnitudes, a fluxgate magnetometer to measure field components and an optical system to measure fluxgate magnetometer orientation. Early results concerned spherical harmonic models, fields due to ionospheric and magnetospheric currents, the identification and interpretation of fields from lithospheric sources. The preliminary results confirm the possibility of separating the measured field into core, crustal and external components, and represent significant developments in analytical techniques in main-field modelling and the physics of the field sources.

Unconventional spin dynamics in the honeycomb-lattice material α -RuCl3 : High-field electron spin resonance studies

NASA Astrophysics Data System (ADS)

Ponomaryov, A. N.; Schulze, E.; Wosnitza, J.; Lampen-Kelley, P.; Banerjee, A.; Yan, J.-Q.; Bridges, C. A.; Mandrus, D. G.; Nagler, S. E.; Kolezhuk, A. K.; Zvyagin, S. A.

2017-12-01

We present high-field electron spin resonance (ESR) studies of the honeycomb-lattice material α -RuCl3 , a prime candidate to exhibit Kitaev physics. Two modes of antiferromagnetic resonance were detected in the zigzag ordered phase, with magnetic field applied in the a b plane. A very rich excitation spectrum was observed in the field-induced quantum paramagnetic phase. The obtained data are compared with the results of recent numerical calculations, strongly suggesting a very unconventional multiparticle character of the spin dynamics in α -RuCl3 . The frequency-field diagram of the lowest-energy ESR mode is found consistent with the behavior of the field-induced energy gap, revealed by thermodynamic measurements.

Three-dimensional flow field measurements in a radial inflow turbine scroll using LDV

NASA Technical Reports Server (NTRS)

Malak, M. F.; Hamed, A.; Tabakoff, W.

1986-01-01

The results of an experimental study of the three-dimensional flow field in a radial inflow turbine scroll are presented. A two-color LDV system was used in the measurement of three orthogonal velocity components at 758 points located throughout the scroll and the unvaned portion of the nozzle. The cold flow experimental results are presented for through-flow velocity contours and the cross velocity vectors.

Full-field OCT: ex vivo and in vivo biological imaging applications

NASA Astrophysics Data System (ADS)

Grieve, Katharine; Dubois, Arnaud; Moneron, Gael; Guyot, Elvire; Boccara, Albert C.

2005-04-01

We present results of studies in embryology and ophthalmology performed using our ultrahigh-resolution full-field OCT system. We also discuss recent developments to our ultrashort acquisition time full-field optical coherence tomography system designed to allow in vivo biological imaging. Preliminary results of high-speed imaging in biological samples are presented. The core of the experimental setup is the Linnik interferometer, illuminated by a white light source. En face tomographic images are obtained in real-time without scanning by computing the difference of two phase-opposed interferometric images recorded by high-resolution CCD cameras. An isotropic spatial resolution of ~1 μm is achieved thanks to the short source coherence length and the use of high numerical aperture microscope objectives. A detection sensitivity of ~90 dB is obtained by means of image averaging and pixel binning. In ophthalmology, reconstructed xz images from rat ocular tissue are presented, where cellular-level structures in the retina are revealed, demonstrating the unprecedented resolution of our instrument. Three-dimensional reconstructions of the mouse embryo allowing the study of the establishment of the anterior-posterior axis are shown. Finally we present the first results of embryonic imaging using the new rapid acquisition full-field OCT system, which offers an acquisition time of 10 μs per frame.

Spherical cloaking using nonlinear transformations for improved segmentation into concentric isotropic coatings.

PubMed

Qiu, Cheng-Wei; Hu, Li; Zhang, Baile; Wu, Bae-Ian; Johnson, Steven G; Joannopoulos, John D

2009-08-03

Two novel classes of spherical invisibility cloaks based on nonlinear transformation have been studied. The cloaking characteristics are presented by segmenting the nonlinear transformation based spherical cloak into concentric isotropic homogeneous coatings. Detailed investigations of the optimal discretization (e.g., thickness control of each layer, nonlinear factor, etc.) are presented for both linear and nonlinear spherical cloaks and their effects on invisibility performance are also discussed. The cloaking properties and our choice of optimal segmentation are verified by the numerical simulation of not only near-field electric-field distribution but also the far-field radar cross section (RCS).

Direct Simulation of Reentry Flows with Ionization

NASA Technical Reports Server (NTRS)

Carlson, Ann B.; Hassan, H. A.

1989-01-01

The Direct Simulation Monte Carlo (DSMC) method is applied in this paper to the study of rarefied, hypersonic, reentry flows. The assumptions and simplifications involved with the treatment of ionization, free electrons and the electric field are investigated. A new method is presented for the calculation of the electric field and handling of charged particles with DSMC. In addition, a two-step model for electron impact ionization is implemented. The flow field representing a 10 km/sec shock at an altitude of 65 km is calculated. The effects of the new modeling techniques on the calculation results are presented and discussed.

Potential risk levels of invasive Neoleucinodes elegantalis (small tomato borer) in areas optimal for open-field Solanum lycopersicum (tomato) cultivation in the present and under predicted climate change.

PubMed

da Silva, Ricardo Siqueira; Kumar, Lalit; Shabani, Farzin; Picanço, Marcelo Coutinho

2017-03-01

Neoleucinodes elegantalis is one of the major insect pests of Solanum lycopersicum. Currently, N. elegantalis is present only in America and the Caribbean, and is a threat in the world's largest S. lycopersicum-producing countries. In terms of potential impact on agriculture, the impact of climate change on insect invasions must be a concern. At present, no research exists regarding the effects of climatic change on the risk level of N. elegantalis. The purpose of this study was to develop a model for S. lycopersicum and N. elegantalis, utilizing CLIMEX to determine risk levels of N. elegantalis in open-field S. lycopersicum cultivation in the present and under projected climate change, using the global climate model CSIRO-Mk3.0. Large areas are projected to be suitable for N. elegantalis and optimal for open-field S. lycopersicum cultivation at the present time. However, in the future these areas will become unsuitable for both species. Conversely, other regions in the future may become optimal for open-field S. lycopersicum cultivation, with a varying risk level for N. elegantalis. The risk level results presented here provide a useful tool to design strategies to prevent the introduction and establishment of N. elegantalis in open-field S. lycopersicum cultivation. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Electric field with bipolar structure during magnetic reconnection without a guide field

NASA Astrophysics Data System (ADS)

Guo, Jun

2014-05-01

We present a study on the polarized electric field during the collisionless magnetic reconnection of antiparallel fields using two dimensional particle-in-cell simulations. The simulations demonstrate clearly that electron holes and electric field with bipolar structure are produced during magnetic reconnection without a guide field. The electric field with bipolar structure can be found near the X-line and on the separatrix and the plasma sheet boundary layer, which is consistent with the observations. These structures will elongate electron's time staying in the diffusion region. In addition, the electric fields with tripolar structures are also found in our simulation.

Plot-scale field experiment of surface hydrologic processes with EOS implications

NASA Technical Reports Server (NTRS)

Laymon, Charles A.; Macari, Emir J.; Costes, Nicholas C.

1992-01-01

Plot-scale hydrologic field studies were initiated at NASA Marshall Space Flight Center to a) investigate the spatial and temporal variability of surface and subsurface hydrologic processes, particularly as affected by vegetation, and b) develop experimental techniques and associated instrumentation methodology to study hydrologic processes at increasingly large spatial scales. About 150 instruments, most of which are remotely operated, have been installed at the field site to monitor ground atmospheric conditions, precipitation, interception, soil-water status, and energy flux. This paper describes the nature of the field experiment, instrumentation and sampling rationale, and presents preliminary findings.

TYPES OF ARSENIC AND TREATMENT OPTIONS

EPA Science Inventory

Presentation will discuss the state-of-the-art technology for removal of arsenic from drinking water. Presentation includes results of several EPA field studies on removal of arsenic from existing arsenic removal plants and key results from several EPA sponsored research studies...

The Thistle Field - Analysis of its past performance and optimisation of its future development

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

Bayat, M.G.; Tehrani, D.H.

1985-01-01

The Thistle Field geology and its reservoir performance over the past six years have been reviewed. The latest reservoir simulation study of the field, covering the performance history-matching, and the conclusions of various prediction cases are reported. The special features of PORES, Britoil in-house 3D 3-phase fully implicit numerical simulator and its modeling aids as applied to the Thistle Field are presented.

Use of English Vocabulary Learning Strategies by Thai Tertiary-Level Students in Relation to Fields of Study and Language-Learning Experiences

ERIC Educational Resources Information Center

Boonkongsaen, Nathaya; Intaraprasert, Channarong

2014-01-01

The present study was intended to examine the effects of 1) fields of study (arts, business and science-oriented); and 2) language-learning experiences (whether limited or non-limited to formal classroom instructions) on the use of VLSs among Thai tertiary-level students. The participants were 905 Thai EFL students studying in the Northeast of…

A method to integrate descriptive and experimental field studies at the level of data and empirical concepts1

PubMed Central

Bijou, Sidney W.; Peterson, Robert F.; Ault, Marion H.

1968-01-01

It is the thesis of this paper that data from descriptive and experimental field studies can be interrelated at the level of data and empirical concepts if both sets are derived from frequency-of-occurrence measures. The methodology proposed for a descriptive field study is predicated on three assumptions: (1) The primary data of psychology are the observable interactions of a biological organism and environmental events, past and present. (2) Theoretical concepts and laws are derived from empirical concepts and laws, which in turn are derived from the raw data. (3) Descriptive field studies describe interactions between behavioral and environmental events; experimental field studies provide information on their functional relationships. The ingredients of a descriptive field investigation using frequency measures consist of: (1) specifying in objective terms the situation in which the study is conducted, (2) defining and recording behavioral and environmental events in observable terms, and (3) measuring observer reliability. Field descriptive studies following the procedures suggested here would reveal interesting new relationships in the usual ecological settings and would also provide provocative cues for experimental studies. On the other hand, field-experimental studies using frequency measures would probably yield findings that would suggest the need for describing new interactions in specific natural situations. PMID:16795175

Atomic electric fields revealed by a quantum mechanical approach to electron picodiffraction.

PubMed

Müller, Knut; Krause, Florian F; Béché, Armand; Schowalter, Marco; Galioit, Vincent; Löffler, Stefan; Verbeeck, Johan; Zweck, Josef; Schattschneider, Peter; Rosenauer, Andreas

2014-12-15

By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border to probing subatomic details. A major challenge is the measurement of atomic electric fields using differential phase contrast (DPC) microscopy, traditionally exploiting the concept of a field-induced shift of diffraction patterns. Here we present a simplified quantum theoretical interpretation of DPC. This enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright-field detectors. The methodical development yielding atomic electric field, charge and electron density is performed using simulations for binary GaN as an ideal model system. We then present a detailed experimental study of SrTiO3 yielding atomic electric fields, validated by comprehensive simulations. With this interpretation and upgraded instrumentation, STEM is capable of quantifying atomic electric fields and high-contrast imaging of light atoms.

Atomic electric fields revealed by a quantum mechanical approach to electron picodiffraction

NASA Astrophysics Data System (ADS)

Müller, Knut; Krause, Florian F.; Béché, Armand; Schowalter, Marco; Galioit, Vincent; Löffler, Stefan; Verbeeck, Johan; Zweck, Josef; Schattschneider, Peter; Rosenauer, Andreas

2014-12-01

By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border to probing subatomic details. A major challenge is the measurement of atomic electric fields using differential phase contrast (DPC) microscopy, traditionally exploiting the concept of a field-induced shift of diffraction patterns. Here we present a simplified quantum theoretical interpretation of DPC. This enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright-field detectors. The methodical development yielding atomic electric field, charge and electron density is performed using simulations for binary GaN as an ideal model system. We then present a detailed experimental study of SrTiO3 yielding atomic electric fields, validated by comprehensive simulations. With this interpretation and upgraded instrumentation, STEM is capable of quantifying atomic electric fields and high-contrast imaging of light atoms.

Atomic electric fields revealed by a quantum mechanical approach to electron picodiffraction

PubMed Central

Müller, Knut; Krause, Florian F.; Béché, Armand; Schowalter, Marco; Galioit, Vincent; Löffler, Stefan; Verbeeck, Johan; Zweck, Josef; Schattschneider, Peter; Rosenauer, Andreas

2014-01-01

By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border to probing subatomic details. A major challenge is the measurement of atomic electric fields using differential phase contrast (DPC) microscopy, traditionally exploiting the concept of a field-induced shift of diffraction patterns. Here we present a simplified quantum theoretical interpretation of DPC. This enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright-field detectors. The methodical development yielding atomic electric field, charge and electron density is performed using simulations for binary GaN as an ideal model system. We then present a detailed experimental study of SrTiO3 yielding atomic electric fields, validated by comprehensive simulations. With this interpretation and upgraded instrumentation, STEM is capable of quantifying atomic electric fields and high-contrast imaging of light atoms. PMID:25501385

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

Goltz, M.N.; Hopkins, G.D.; Kawakami, B.T.

A trichloroethylene (TCE) ground water plume at Edwards AFB in Southern California is being used to demonstrate in situ aerobic cometabolic bioremediation in the field. The bioremediation system that will be demonstrated at Edwards was developed over nine years of research and testing in the laboratory and at a pilot field site located at Moffett Federal Airfield in Mountain View, California. Studies conducted at the Moffett field site have demonstrated that TCE can be effectively biodegraded cometabolically through the introduction into the subsurface of a primary substrate and an oxygen source to support the growth and energy requirements of amore » native population of microorganisms. A system to demonstrate the feasibility of in situ aerobic cometabolic bioremediation is presently being constructed at Edwards, using an area of the plume having TCE concentrations ranging up to 1 mg/L. A major objective of the Edwards study will be to investigate how a primary substrate and an oxygen source can be efficiently mixed and transported to indigenous microorganisms, in order to promote cometabolic degradation of TCE. In this presentation, the earlier studies at Moffett, as well as the preliminary modeling work and site characterization which have been conducted in preparation for the Edwards demonstration, will be presented. In addition, problems encountered and lessons learned bringing an innovative technology from the laboratory to the field will be discussed.« less

Study for the quality assessment of abstracts presented to Italian public health national conferences: a six years survey.

PubMed

Castaldi, S; Colombo, A; D'Errico, R; Bert, F; Siliquini, R; Ceruti, M; Curti, S; Gaietta, M; Garavelli, E; Legouellec, L; Lovato, E; Martinese, M; Visco, F

2013-01-01

Oral and poster presentations at congresses are essential to spread scientific knowledge among the medical community. Many scientific societies have analyzed the quality of papers presented at their meetings but no information on abstracts' evaluation has been presented in Public Health field. This study aims to examine the quality of abstracts presented at annual meetings of Italian Public Health Society (SItI) in the period 2005-2010 through a validated checklist grid, evaluating eight dimensions: Inherency, Structure, Originality, Objectives, Study design, Sources, Results, Conclusions. Each item was scored from 0 to 3 points (max score: 24) and we used the average score in our study (15) as threshold of good quality. A multivariate analysis was performed in order to investigate predictors of score of abstracts presented. A total of 4,399 abstracts (1,172 oral communications, 3,227 posters) was examined. Around 60% were submitted by Universities and around 40% were from Central Italy. The highest quality was found in the fields of Vaccines (average score 18.9), Infectious Diseases (18) and in abstracts submitted by Universities (16.4). Predictors of lower quality identified were geographical area and affiliation (p= 0.002). Abstracts containing well-written Results, Conclusions and Objectives (3 points) were more likely to be of high quality(OR=55.6, OR=41.9, and OR=157.4; p>0.001) CONCLUSIONS: This is the first European study evaluating the quality of abstracts in the public health field. A reliable evaluation tool is fundamental to offer a transparent methodology of assessment and to improve the quality of research.

Combining near- and far-field exposure for an organ-specific and whole-body RF-EMF proxy for epidemiological research: a reference case.

PubMed

Lauer, Oliver; Frei, Patrizia; Gosselin, Marie-Christine; Joseph, Wout; Röösli, Martin; Fröhlich, Jürg

2013-07-01

A framework for the combination of near-field (NF) and far-field (FF) radio frequency electromagnetic exposure sources to the average organ and whole-body specific absorption rates (SARs) is presented. As a reference case, values based on numerically derived SARs for whole-body and individual organs and tissues are combined with realistic exposure data, which have been collected using personal exposure meters during the Swiss Qualifex study. The framework presented can be applied to any study region where exposure data is collected by appropriate measurement equipment. Based on results derived from the data for the region of Basel, Switzerland, the relative importance of NF and FF sources to the personal exposure is examined for three different study groups. The results show that a 24-h whole-body averaged exposure of a typical mobile phone user is dominated by the use of his or her own mobile phone when a Global System for Mobile Communications (GSM) 900 or GSM 1800 phone is used. If only Universal Mobile Telecommunications System (UMTS) phones are used, the user would experience a lower exposure level on average caused by the lower average output power of UMTS phones. Data presented clearly indicate the necessity of collecting band-selective exposure data in epidemiological studies related to electromagnetic fields. Copyright © 2013 Wiley Periodicals, Inc.

Drop-Out in Schools in India: Minor Field Studies in Orissa 1990. Educational and Psychological Interactions. No. 112.

ERIC Educational Resources Information Center

Ekstrand, Gudrun, Ed.

This document consists of a report on the Minor Field Studies (MFS) program of the Swedish International Development Authority (SIDA) and contains two MFS papers by teacher trainees at the Malmo School of Education in Sweden. The papers presented are "Drop-outs in Orissa," by Elisabeth Rosen, and "Education in India: A Study of…

Effects of an electric field on white sharks: in situ testing of an electric deterrent.

PubMed

Huveneers, Charlie; Rogers, Paul J; Semmens, Jayson M; Beckmann, Crystal; Kock, Alison A; Page, Brad; Goldsworthy, Simon D

2013-01-01

Elasmobranchs can detect minute electromagnetic fields, <1 nV cm(-1), using their ampullae of Lorenzini. Behavioural responses to electric fields have been investigated in various species, sometimes with the aim to develop shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1) the behaviour of 18 white sharks (Carcharodon carcharias) near a static bait, and (2) the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks.

Effects of an Electric Field on White Sharks: In Situ Testing of an Electric Deterrent

PubMed Central

Huveneers, Charlie; Rogers, Paul J.; Semmens, Jayson M.; Beckmann, Crystal; Kock, Alison A.; Page, Brad; Goldsworthy, Simon D.

2013-01-01

Elasmobranchs can detect minute electromagnetic fields, <1 nVcm–1, using their ampullae of Lorenzini. Behavioural responses to electric fields have been investigated in various species, sometimes with the aim to develop shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1) the behaviour of 18 white sharks (Carcharodon carcharias) near a static bait, and (2) the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks. PMID:23658766

CHARMM additive and polarizable force fields for biophysics and computer-aided drug design.

PubMed

Vanommeslaeghe, K; MacKerell, A D

2015-05-01

Molecular Mechanics (MM) is the method of choice for computational studies of biomolecular systems owing to its modest computational cost, which makes it possible to routinely perform molecular dynamics (MD) simulations on chemical systems of biophysical and biomedical relevance. As one of the main factors limiting the accuracy of MD results is the empirical force field used, the present paper offers a review of recent developments in the CHARMM additive force field, one of the most popular biomolecular force fields. Additionally, we present a detailed discussion of the CHARMM Drude polarizable force field, anticipating a growth in the importance and utilization of polarizable force fields in the near future. Throughout the discussion emphasis is placed on the force fields' parametrization philosophy and methodology. Recent improvements in the CHARMM additive force field are mostly related to newly found weaknesses in the previous generation of additive force fields. Beyond the additive approximation is the newly available CHARMM Drude polarizable force field, which allows for MD simulations of up to 1μs on proteins, DNA, lipids and carbohydrates. Addressing the limitations ensures the reliability of the new CHARMM36 additive force field for the types of calculations that are presently coming into routine computational reach while the availability of the Drude polarizable force fields offers an inherently more accurate model of the underlying physical forces driving macromolecular structures and dynamics. This article is part of a Special Issue entitled "Recent developments of molecular dynamics". Copyright © 2014 Elsevier B.V. All rights reserved.

Historical Research: How to Fit Minority and Women's Studies into Mathematics Class

ERIC Educational Resources Information Center

Saraco, Margaret R.

2008-01-01

This article presents a lesson for studying minority and women's contributions to the field of mathematics in the middle school classroom. This lesson may be able to stem the tide of the shrinking number of students entering the field of mathematics by helping them become interested in its history. Nonetheless, this project encourages students to…

A reservoir optimization study--El Bunduq Field, Abu Dhabi, Qatar

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

Blashbush, J.L.; Nagai, R.B.; Ogimoto, T.

El Bunduq reservoir is located in the offshore area of Abu Dhabi and Qatar. The field was shut-in in July 1979 due to production with high gas-oil ratios. Pressure differences of 200-400 psi between the flanks and the central part of the reservoir were still present almost four years after the field was shut-in. A comprehensive reservoir engineering study determined that the reasons for this behavior were the deteriorating qualities of the reservoir rock downstructure and the presence of a tar mat around the field. After the field behavior was history matched, model studies of a representative sector of themore » field indicated that peripheral waterflooding would recover less than 15 percent of the OOIP in a period of 30 years. However, pattern injection recoveries were calculated to be at least twice as high. Several full field alternatives were investigated to optimize the development of the reservoir under a pattern waterflood. This paper summarizes the various studies that led to the acceptance of the idea of pattern development over peripheral injection, as a result of the unique characteristics of this field.« less

First Results from the AKARI FU-HYU Mission Program

NASA Astrophysics Data System (ADS)

Pearson, C.; Serjeant, S.; Takagi, T.; Jeong, W.-S.; Negrello, M.; Matsuhara, H.; Wada, T.; Oyabu, S.; Lee, H. M.; Im, M.

2009-12-01

The AKARI FU-HYU mission program has carried out mid-infrared imaging of several well studied Spitzer fields. This imaging fills in the wavelength coverage lacking from the Spitzer surveys and gives an extremely high scientific return for minimal input for AKARI. We select fields already rich in multi-wavelength data from radio to X-ray wavelengths and present the results from our initial analysis in the GOODS-N field. We utilize the comprehansive multiwavelength coverage in the GOODS-N field to produce a multiwavelength catalogue from infrared to ultraviolet wavelengths including photometric redshifts. Using the FU-HYU catalogue we present colour-colour diagrams that map the passage of PAH features through our observation bands. These colour-colours diagrams are used as tools to extract anomalous colour populations, in particular a population of Silicate Break galaxies from the GOODS-N field.

Seeing the Invisible: Educating the Public on Planetary Magnetic Fields and How they Affect Atmospheres

NASA Astrophysics Data System (ADS)

Fillingim, M. O.; Brain, D. A.; Peticolas, L. M.; Schultz, G.; Yan, D.; Guevara, S.; Randol, S.

2009-12-01

Magnetic fields and charged particles are difficult for school children, the general public, and scientists alike to visualize. But studies of planetary magnetospheres and ionospheres have broad implications for planetary evolution, from the deep interior to the ancient climate, that are important to communicate to each of these audiences. This presentation will highlight the visualization materials that we are developing to educate audiences on the magnetic fields of planets and how they affect atmospheres. The visualization materials that we are developing consist of simplified data sets that can be displayed on spherical projection systems and portable 3-D rigid models of planetary magnetic fields.We are developing presentations for science museums and classrooms that relate fundamental information about the Martian magnetic field, how it differs from Earth’s, and why the differences are significant.

Spatially resolved and time-resolved imaging of transport of indirect excitons in high magnetic fields

NASA Astrophysics Data System (ADS)

Dorow, C. J.; Hasling, M. W.; Calman, E. V.; Butov, L. V.; Wilkes, J.; Campman, K. L.; Gossard, A. C.

2017-06-01

We present the direct measurements of magnetoexciton transport. Excitons give the opportunity to realize the high magnetic-field regime for composite bosons with magnetic fields of a few tesla. Long lifetimes of indirect excitons allow the study of kinetics of magnetoexciton transport with time-resolved optical imaging of exciton photoluminescence. We performed spatially, spectrally, and time-resolved optical imaging of transport of indirect excitons in high magnetic fields. We observed that an increasing magnetic field slows down magnetoexciton transport. The time-resolved measurements of the magnetoexciton transport distance allowed for an experimental estimation of the magnetoexciton diffusion coefficient. An enhancement of the exciton photoluminescence energy at the laser excitation spot was found to anticorrelate with the exciton transport distance. A theoretical model of indirect magnetoexciton transport is presented and is in agreement with the experimental data.

Observations of the Earth's magnetic field from the Space Station: Measurement at high and extremely low altitude using Space Station-controlled free-flyers

NASA Technical Reports Server (NTRS)

Webster, W., Jr.; Frawley, J. J.; Stefanik, M.

1984-01-01

Simulation studies established that the main (core), crustal and electrojet components of the Earth's magnetic field can be observed with greater resolution or over a longer time-base than is presently possible by using the capabilities provided by the space station. Two systems are studied. The first, a large lifetime, magnetic monitor would observe the main field and its time variation. The second, a remotely-piloted, magnetic probe would observe the crustal field at low altitude and the electrojet field in situ. The system design and the scientific performance of these systems is assessed. The advantages of the space station are reviewed.

Possibilities and limitations of current stereo-endoscopy.

PubMed

Mueller-Richter, U D A; Limberger, A; Weber, P; Ruprecht, K W; Spitzer, W; Schilling, M

2004-06-01

Stereo-endoscopy has become a commonly used technology. In many comparative studies striking advantages of stereo-endoscopy over two-dimensional presentation could not be proven. To show the potential and fields for further improvement of this technology is the aim of this article. The physiological basis of three-dimensional vision limitations of current stereo-endoscopes is discussed and fields for further research are indicated. New developments in spatial picture acquisition and spatial picture presentation are discussed. Current limitations of stereo-endoscopy that prevent a better ranking in comparative studies with two-dimensional presentation are mainly based on insufficient picture acquisition. Devices for three-dimensional picture presentation are at a more advanced developmental stage than devices for three-dimensional picture acquisition. Further research should emphasize the development of new devices for three-dimensional picture acquisition.

An overview of the CalNex 2010 field mission: research to extend the understanding of climate and air quality issues in California (Invited)

NASA Astrophysics Data System (ADS)

Ryerson, T. B.

2009-12-01

CalNex is a major field study planned for May and June of 2010. The study, led by NOAA and the California Air Resources Board, coordinates many interagency partners with independent but complementary capabilities and goals. Observations from surface-, aircraft-, ship-, and space-based sensors, along with Lagrangian and Eulerian modeling studies, will be used to extend previous studies and contribute new data and understanding to issues relevant to climate change and air quality in California. This overview will present the integrated approach that will be taken in CalNex, utilizing long-term surface observations, instrumented tall towers, several major intensive ground sites, a network of daily ozonesonde launches, a radar profiling network, multiple instrumented research aircraft, a research vessel, and retrievals from several satellites. The primary CalNex science questions and experimental strategies to address them will be presented, with illustrations and data examples taken from recent field projects in California to provide context for the upcoming study.

Creativity and psychopathology: a systematic review.

PubMed

Thys, Erik; Sabbe, Bernard; De Hert, Marc

2014-01-01

The possible link between creativity and psychopathology has been a long-time focus of research up to the present day. However, the research results in this field are heterogeneous and contradictory. Links between creativity and specific psychiatric disorders have been confirmed and refuted in different studies. This disparity is partly explained by the methodological challenges peculiar to this field. In this systematic review of the literature from 1950, research articles in the field of creativity and psychopathology are presented, focusing on the methodology and results of the collected studies. This review confirms the methodological problems and the heterogeneity of the study designs and results. The assessment of psychopathology, but more so of creativity, remains a fundamental challenge. On the whole, study results cautiously confirm an association between creativity and both bipolar disorder and schizotypy. The research on creativity and psychopathology is hampered by serious methodological problems. Study results are to be interpreted with caution and future research needs more methodological rigor. © 2014 S. Karger AG, Basel.

Flow field and performance characteristics of combustor diffusers: A basic study

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

Hestermann, R.; Kim, S.; Ben Khaled, A.

1995-10-01

Results of a detailed study concerning the influence of geometric as well as fluid mechanic parameters o the performance of a plane model combustor diffuser in cold flow are presented. For a qualitative insight into the complex flow field inside the prediffuser, the sudden expansion region, and the flow field around the flame tube dome, results of a flow visualization study with the hydrogen bubble method as well as with the ink jet method are presented for different opening angles of the prediffuser and for different flame tube distances. Also, quantitative data from detailed measurements with LDV and conventional pressuremore » probes in a geometrically similar air-driven setup are presented. These data clearly demonstrate the effect of boundary layer thickness as well as the influence of different turbulence levels at the entry of the prediffuser on the performance characteristics of combustor diffusers. The possibility of getting an unseparated flow field inside the prediffuser even at large opening angles by appropriately matching the diffuser`s opening angle and the flame tube distance is demonstrated. Also, for flows with an increased turbulence level at the entrance--all other conditions held constant--an increased opening angle can be realized without experiencing flow separation. The comparison of the experimental data with predictions utilizing a finite-volume-code based on a body-fitted coordinate system for diffusers with an included total opening angle less than 18 deg demonstrates the capability of describing the flow field in combustor diffusers with reasonable accuracy.« less

Gravitational waves in modified teleparallel theories of gravity.

PubMed

Abedi, Habib; Capozziello, Salvatore

2018-01-01

Teleparallel theory of gravity and its modifications have been studied extensively in literature. However, gravitational waves has not been studied enough in the framework of teleparallelism. In the present study, we discuss gravitational waves in general theories of teleparallel gravity containing the torsion scalar T , the boundary term B and a scalar field ϕ . The goal is to classify possible new polarizations generalizing results presented in Bamba et al. (Phys Lett B 727:194-198, arXiv:1309.2698, 2013). We show that, if the boundary term is minimally coupled to the torsion scalar and the scalar field, gravitational waves have the same polarization modes of General Relativity.

Gravitational waves in modified teleparallel theories of gravity

NASA Astrophysics Data System (ADS)

Abedi, Habib; Capozziello, Salvatore

2018-06-01

Teleparallel theory of gravity and its modifications have been studied extensively in literature. However, gravitational waves has not been studied enough in the framework of teleparallelism. In the present study, we discuss gravitational waves in general theories of teleparallel gravity containing the torsion scalar T, the boundary term B and a scalar field φ . The goal is to classify possible new polarizations generalizing results presented in Bamba et al. (Phys Lett B 727:194-198, arXiv:1309.2698, 2013). We show that, if the boundary term is minimally coupled to the torsion scalar and the scalar field, gravitational waves have the same polarization modes of General Relativity.

Fokker-Planck equation for the non-Markovian Brownian motion in the presence of a magnetic field

NASA Astrophysics Data System (ADS)

Das, Joydip; Mondal, Shrabani; Bag, Bidhan Chandra

2017-10-01

In the present study, we have proposed the Fokker-Planck equation in a simple way for a Langevin equation of motion having ordinary derivative (OD), the Gaussian random force and a generalized frictional memory kernel. The equation may be associated with or without conservative force field from harmonic potential. We extend this method for a charged Brownian particle in the presence of a magnetic field. Thus, the present method is applicable for a Langevin equation of motion with OD, the Gaussian colored thermal noise and any kind of linear force field that may be conservative or not. It is also simple to apply this method for the colored Gaussian noise that is not related to the damping strength.

Fokker-Planck equation for the non-Markovian Brownian motion in the presence of a magnetic field.

PubMed

Das, Joydip; Mondal, Shrabani; Bag, Bidhan Chandra

2017-10-28

In the present study, we have proposed the Fokker-Planck equation in a simple way for a Langevin equation of motion having ordinary derivative (OD), the Gaussian random force and a generalized frictional memory kernel. The equation may be associated with or without conservative force field from harmonic potential. We extend this method for a charged Brownian particle in the presence of a magnetic field. Thus, the present method is applicable for a Langevin equation of motion with OD, the Gaussian colored thermal noise and any kind of linear force field that may be conservative or not. It is also simple to apply this method for the colored Gaussian noise that is not related to the damping strength.

Description of rotating N=Z nuclei in terms of isovector pairing

NASA Astrophysics Data System (ADS)

Afanasjev, A. V.; Frauendorf, S.

2005-06-01

A systematic investigation of the rotating N=Z even-even nuclei in the mass A=68-80 region has been performed within the frameworks of the cranked relativistic mean field, cranked relativistic Hartree-Bogoliubov theories, and cranked Nilsson-Strutinsky approach. Most of the experimental data are well accounted for in the calculations. The present study suggests the presence of strong isovector np pair field at low spin, whose strength is defined by the isospin symmetry. At high spin, the isovector pair field is destroyed and the data are well described by the calculations assuming zero pairing. No clear evidence for the existence of the isoscalar t=0 np pairing has been obtained in the present investigation performed at the mean field level.

POLARIZED LINE FORMATION IN NON-MONOTONIC VELOCITY FIELDS

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

Sampoorna, M.; Nagendra, K. N., E-mail: sampoorna@iiap.res.in, E-mail: knn@iiap.res.in

2016-12-10

For a correct interpretation of the observed spectro-polarimetric data from astrophysical objects such as the Sun, it is necessary to solve the polarized line transfer problems taking into account a realistic temperature structure, the dynamical state of the atmosphere, a realistic scattering mechanism (namely, the partial frequency redistribution—PRD), and the magnetic fields. In a recent paper, we studied the effects of monotonic vertical velocity fields on linearly polarized line profiles formed in isothermal atmospheres with and without magnetic fields. However, in general the velocity fields that prevail in dynamical atmospheres of astrophysical objects are non-monotonic. Stellar atmospheres with shocks, multi-componentmore » supernova atmospheres, and various kinds of wave motions in solar and stellar atmospheres are examples of non-monotonic velocity fields. Here we present studies on the effect of non-relativistic non-monotonic vertical velocity fields on the linearly polarized line profiles formed in semi-empirical atmospheres. We consider a two-level atom model and PRD scattering mechanism. We solve the polarized transfer equation in the comoving frame (CMF) of the fluid using a polarized accelerated lambda iteration method that has been appropriately modified for the problem at hand. We present numerical tests to validate the CMF method and also discuss the accuracy and numerical instabilities associated with it.« less

Estimating thermal performance curves from repeated field observations

USGS Publications Warehouse

Childress, Evan; Letcher, Benjamin H.

2017-01-01

Estimating thermal performance of organisms is critical for understanding population distributions and dynamics and predicting responses to climate change. Typically, performance curves are estimated using laboratory studies to isolate temperature effects, but other abiotic and biotic factors influence temperature-performance relationships in nature reducing these models' predictive ability. We present a model for estimating thermal performance curves from repeated field observations that includes environmental and individual variation. We fit the model in a Bayesian framework using MCMC sampling, which allowed for estimation of unobserved latent growth while propagating uncertainty. Fitting the model to simulated data varying in sampling design and parameter values demonstrated that the parameter estimates were accurate, precise, and unbiased. Fitting the model to individual growth data from wild trout revealed high out-of-sample predictive ability relative to laboratory-derived models, which produced more biased predictions for field performance. The field-based estimates of thermal maxima were lower than those based on laboratory studies. Under warming temperature scenarios, field-derived performance models predicted stronger declines in body size than laboratory-derived models, suggesting that laboratory-based models may underestimate climate change effects. The presented model estimates true, realized field performance, avoiding assumptions required for applying laboratory-based models to field performance, which should improve estimates of performance under climate change and advance thermal ecology.

Properties of the superconductor in accelerator dipole magnets

NASA Astrophysics Data System (ADS)

Teravest, Derk

Several aspects of the application of superconductors to high field dipole magnets for particle accelerators are discussed. The attention is focused on the 10 tesla (1 m model) magnet that is envisaged for the future Large Hadron Collider (LHC) accelerator. The basic motivation behind the study is the intention of employing superconductors to their utmost performance. An overview of practical supercomputers, their applications and their impact on high field dipole magnets used for particle accelerators, is presented. The LHC reference design for the dipole magnets is outlined. Several models were used to study the influence of a number of factors in the shape and in particular, the deviation from the shape that is due to the flux flow state. For the investigated extrinsic and intrinsic factors, a classification can be made with respect to the effect on the shape of the characteristic of a multifilamentary wire. The optimization of the coil structure for high field dipole magnets, with respect to the field quality is described. An analytical model for solid and hollow filaments, to calculate the effect of filament magnetization in the quality of the dipole field, is presented.

Equivalent magnetic vector potential model for low-frequency magnetic exposure assessment

NASA Astrophysics Data System (ADS)

Diao, Y. L.; Sun, W. N.; He, Y. Q.; Leung, S. W.; Siu, Y. M.

2017-10-01

In this paper, a novel source model based on a magnetic vector potential for the assessment of induced electric field strength in a human body exposed to the low-frequency (LF) magnetic field of an electrical appliance is presented. The construction of the vector potential model requires only a single-component magnetic field to be measured close to the appliance under test, hence relieving considerable practical measurement effort—the radial basis functions (RBFs) are adopted for the interpolation of discrete measurements; the magnetic vector potential model can then be directly constructed by summing a set of simple algebraic functions of RBF parameters. The vector potentials are then incorporated into numerical calculations as the equivalent source for evaluations of the induced electric field in the human body model. The accuracy and effectiveness of the proposed model are demonstrated by comparing the induced electric field in a human model to that of the full-wave simulation. This study presents a simple and effective approach for modelling the LF magnetic source. The result of this study could simplify the compliance test procedure for assessing an electrical appliance regarding LF magnetic exposure.

Equivalent magnetic vector potential model for low-frequency magnetic exposure assessment.

PubMed

Diao, Y L; Sun, W N; He, Y Q; Leung, S W; Siu, Y M

2017-09-21

In this paper, a novel source model based on a magnetic vector potential for the assessment of induced electric field strength in a human body exposed to the low-frequency (LF) magnetic field of an electrical appliance is presented. The construction of the vector potential model requires only a single-component magnetic field to be measured close to the appliance under test, hence relieving considerable practical measurement effort-the radial basis functions (RBFs) are adopted for the interpolation of discrete measurements; the magnetic vector potential model can then be directly constructed by summing a set of simple algebraic functions of RBF parameters. The vector potentials are then incorporated into numerical calculations as the equivalent source for evaluations of the induced electric field in the human body model. The accuracy and effectiveness of the proposed model are demonstrated by comparing the induced electric field in a human model to that of the full-wave simulation. This study presents a simple and effective approach for modelling the LF magnetic source. The result of this study could simplify the compliance test procedure for assessing an electrical appliance regarding LF magnetic exposure.

Noncommutative Field Theories and (super)string Field Theories

NASA Astrophysics Data System (ADS)

Aref'eva, I. Ya.; Belov, D. M.; Giryavets, A. A.; Koshelev, A. S.; Medvedev, P. B.

2002-11-01

In this lecture notes we explain and discuss some ideas concerning noncommutative geometry in general, as well as noncommutative field theories and string field theories. We consider noncommutative quantum field theories emphasizing an issue of their renormalizability and the UV/IR mixing. Sen's conjectures on open string tachyon condensation and their application to the D-brane physics have led to wide investigations of the covariant string field theory proposed by Witten about 15 years ago. We review main ingredients of cubic (super)string field theories using various formulations: functional, operator, conformal and the half string formalisms. The main technical tools that are used to study conjectured D-brane decay into closed string vacuum through the tachyon condensation are presented. We describe also methods which are used to study the cubic open string field theory around the tachyon vacuum: construction of the sliver state, "comma" and matrix representations of vertices.

A PARAMETRIC STUDY OF BCS RF SURFACE IMPEDANCE WITH MAGNETIC FIELD USING THE XIAO CODE

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

Reece, Charles E.; Xiao, Binping

2013-09-01

A recent new analysis of field-dependent BCS rf surface impedance based on moving Cooper pairs has been presented.[1] Using this analysis coded in Mathematica TM, survey calculations have been completed which examine the sensitivities of this surface impedance to variation of the BCS material parameters and temperature. The results present a refined description of the "best theoretical" performance available to potential applications with corresponding materials.

POLARIZED LINE FORMATION IN MOVING ATMOSPHERES WITH PARTIAL FREQUENCY REDISTRIBUTION AND A WEAK MAGNETIC FIELD

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

Sampoorna, M.; Nagendra, K. N., E-mail: sampoorna@iiap.res.in, E-mail: knn@iiap.res.in

2015-10-10

The dynamical state of the solar and stellar atmospheres depends on the macroscopic velocity fields prevailing within them. The presence of such velocity fields in the line formation regions strongly affects the polarized radiation field emerging from these atmospheres. Thus it becomes necessary to solve the radiative transfer equation for polarized lines in moving atmospheres. Solutions based on the “observer’s frame method” are computationally expensive to obtain, especially when partial frequency redistribution (PRD) in line scattering and large-amplitude velocity fields are taken into account. In this paper we present an efficient alternative method of solution, namely, the comoving frame technique,more » to solve the polarized PRD line formation problems in the presence of velocity fields. We consider one-dimensional planar isothermal atmospheres with vertical velocity fields. We present a study of the effect of velocity fields on the emergent linear polarization profiles formed in optically thick moving atmospheres. We show that the comoving frame method is far superior when compared to the observer’s frame method in terms of the computational speed and memory requirements.« less

Fowler Nordheim theory of carbon nanotube based field emitters

NASA Astrophysics Data System (ADS)

Parveen, Shama; Kumar, Avshish; Husain, Samina; Husain, Mushahid

2017-01-01

Field emission (FE) phenomena are generally explained in the frame-work of Fowler Nordheim (FN) theory which was given for flat metal surfaces. In this work, an effort has been made to present the field emission mechanism in carbon nanotubes (CNTs) which have tip type geometry at nanoscale. High aspect ratio of CNTs leads to large field enhancement factor and lower operating voltages because the electric field strength in the vicinity of the nanotubes tip can be enhanced by thousand times. The work function of nanostructure by using FN plot has been calculated with reverse engineering. With the help of modified FN equation, an important formula for effective emitting area (active area for emission of electrons) has been derived and employed to calculate the active emitting area for CNT field emitters. Therefore, it is of great interest to present a state of art study on the complete solution of FN equation for CNTs based field emitter displays. This manuscript will also provide a better understanding of calculation of different FE parameters of CNTs field emitters using FN equation.

Fractional Poisson Fields and Martingales

NASA Astrophysics Data System (ADS)

Aletti, Giacomo; Leonenko, Nikolai; Merzbach, Ely

2018-02-01

We present new properties for the Fractional Poisson process (FPP) and the Fractional Poisson field on the plane. A martingale characterization for FPPs is given. We extend this result to Fractional Poisson fields, obtaining some other characterizations. The fractional differential equations are studied. We consider a more general Mixed-Fractional Poisson process and show that this process is the stochastic solution of a system of fractional differential-difference equations. Finally, we give some simulations of the Fractional Poisson field on the plane.

Observation of linear and quadratic magnetic field-dependence of magneto-photocurrents in InAs/GaSb superlattice

PubMed Central

2014-01-01

We experimentally studied the magneto-photocurrents generated by direct interband transition in InAs/GaSb type II superlattice. By varying the magnetic field direction, we observed that an in-plane magnetic field induces a photocurrent linearly proportional to the magnetic field; however, a magnetic field tilted to the sample plane induces a photocurrent presenting quadratic magnetic field dependence. The magneto-photocurrents in both conditions are insensitive to the polarization state of the incident light. Theoretical models involving excitation, relaxation and Hall effect are utilized to explain the experimental results. PMID:24936166

Heat source reconstruction from noisy temperature fields using an optimised derivative Gaussian filter

NASA Astrophysics Data System (ADS)

Delpueyo, D.; Balandraud, X.; Grédiac, M.

2013-09-01

The aim of this paper is to present a post-processing technique based on a derivative Gaussian filter to reconstruct heat source fields from temperature fields measured by infrared thermography. Heat sources can be deduced from temperature variations thanks to the heat diffusion equation. Filtering and differentiating are key-issues which are closely related here because the temperature fields which are processed are unavoidably noisy. We focus here only on the diffusion term because it is the most difficult term to estimate in the procedure, the reason being that it involves spatial second derivatives (a Laplacian for isotropic materials). This quantity can be reasonably estimated using a convolution of the temperature variation fields with second derivatives of a Gaussian function. The study is first based on synthetic temperature variation fields corrupted by added noise. The filter is optimised in order to reconstruct at best the heat source fields. The influence of both the dimension and the level of a localised heat source is discussed. Obtained results are also compared with another type of processing based on an averaging filter. The second part of this study presents an application to experimental temperature fields measured with an infrared camera on a thin plate in aluminium alloy. Heat sources are generated with an electric heating patch glued on the specimen surface. Heat source fields reconstructed from measured temperature fields are compared with the imposed heat sources. Obtained results illustrate the relevancy of the derivative Gaussian filter to reliably extract heat sources from noisy temperature fields for the experimental thermomechanics of materials.

A New Method for Analyzing Near-Field Faraday Probe Data in Hall Thrusters

NASA Technical Reports Server (NTRS)

Huang, Wensheng; Shastry, Rohit; Herman, Daniel A.; Soulas, George C.; Kamhawi, Hani

2013-01-01

This paper presents a new method for analyzing near-field Faraday probe data obtained from Hall thrusters. Traditional methods spawned from far-field Faraday probe analysis rely on assumptions that are not applicable to near-field Faraday probe data. In particular, arbitrary choices for the point of origin and limits of integration have made interpretation of the results difficult. The new method, called iterative pathfinding, uses the evolution of the near-field plume with distance to provide feedback for determining the location of the point of origin. Although still susceptible to the choice of integration limits, this method presents a systematic approach to determining the origin point for calculating the divergence angle. The iterative pathfinding method is applied to near-field Faraday probe data taken in a previous study from the NASA-300M and NASA-457Mv2 Hall thrusters. Since these two thrusters use centrally mounted cathodes the current density associated with the cathode plume is removed before applying iterative pathfinding. A procedure is presented for removing the cathode plume. The results of the analysis are compared to far-field probe analysis results. This paper ends with checks on the validity of the new method and discussions on the implications of the results.

A New Method for Analyzing Near-Field Faraday Probe Data in Hall Thrusters

NASA Technical Reports Server (NTRS)

Huang, Wensheng; Shastry, Rohit; Herman, Daniel A.; Soulas, George C.; Kamhawi, Hani

2013-01-01

This paper presents a new method for analyzing near-field Faraday probe data obtained from Hall thrusters. Traditional methods spawned from far-field Faraday probe analysis rely on assumptions that are not applicable to near-field Faraday probe data. In particular, arbitrary choices for the point of origin and limits of integration have made interpretation of the results difficult. The new method, called iterative pathfinding, uses the evolution of the near-field plume with distance to provide feedback for determining the location of the point of origin. Although still susceptible to the choice of integration limits, this method presents a systematic approach to determining the origin point for calculating the divergence angle. The iterative pathfinding method is applied to near-field Faraday probe data taken in a previous study from the NASA-300M and NASA-457Mv2 Hall thrusters. Since these two thrusters use centrally mounted cathodes, the current density associated with the cathode plume is removed before applying iterative pathfinding. A procedure is presented for removing the cathode plume. The results of the analysis are compared to far-field probe analysis results. This paper ends with checks on the validity of the new method and discussions on the implications of the results.

Solar magnetic field studies using the 12 micron emission lines. II - Stokes profiles and vector field samples in sunspots

NASA Technical Reports Server (NTRS)

Hewagama, Tilak; Deming, Drake; Jennings, Donald E.; Osherovich, Vladimir; Wiedemann, Gunter; Zipoy, David; Mickey, Donald L.; Garcia, Howard

1993-01-01

Polarimetric observations at 12 microns of two sunpots are reported. The horizontal distribution of parameters such as magnetic field strength, inclination, azimuth, and magnetic field filling factors are presented along with information about the height dependence of the magnetic field strength. Comparisons with contemporary magnetostatic sunspot models are made. The magnetic data are used to estimate the height of 12 micron line formation. From the data, it is concluded that within a stable sunspot there are no regions that are magnetically filamentary, in the sense of containing both strong-field and field-free regions.

Effects of Resonant Helical Field on Toroidal Field Ripple in IR-T1 Tokamak

NASA Astrophysics Data System (ADS)

Mahdavipour, B.; Salar Elahi, A.; Ghoranneviss, M.

2018-02-01

The toroidal magnetic field which is created by toroidal coils has the ripple in torus space. This magnetic field ripple has an importance in plasma equilibrium and stability studies in tokamak. In this paper, we present the investigation of the interaction between the toroidal magnetic field ripple and resonant helical field (RHF). We have estimated the amplitude of toroidal field ripples without and with RHF (with different q = m/n) ( m = 2, m = 3, m = 4, m = 5, m = 2 & 3, n = 1) using “Comsol Multiphysics” software. The simulations show that RHF has effects on the toroidal ripples.

Biofilm resilience to desiccation in groundwater aquifers: a laboratory and field study.

PubMed

Weaver, L; Webber, J B; Hickson, A C; Abraham, P M; Close, M E

2015-05-01

Groundwater is used as a precious resource for drinking water worldwide. Increasing anthropogenic activity is putting increasing pressure on groundwater resources. One impact of increased groundwater abstraction coupled with increasing dry weather events is the lowering of groundwater levels within aquifers. Biofilms within groundwater aquifers offer protection to the groundwater by removing contaminants entering the aquifer systems from land use activities. The study presented investigated the impact of desiccation events on the biofilms present in groundwater aquifers using field and laboratory experiments. In both field and laboratory experiments a reduction in enzyme activity (glucosidase, esterase and phosphatase) was seen during desiccation compared to wet controls. However, comparing all the data together no significant differences were seen between either wet or desiccated samples or between the start and end of the experiments. In both field and laboratory experiments enzyme activity recovered to start levels after return to wet conditions. The study shows that biofilms within groundwater systems are resilient and can withstand periods of desiccation (4 months). Copyright © 2014 Elsevier B.V. All rights reserved.

Spherical Ethylene/Air Diffusion Flames Subject to Concentric DC Electric Field in Microgravity

NASA Technical Reports Server (NTRS)

Yuan, Z. -G.; Hegde, U.; Faeth, G. M.

2001-01-01

It is well known that microgravity conditions, by eliminating buoyant flow, enable many combustion phenomena to be observed that are not possible to observe at normal gravity. One example is the spherical diffusion flame surrounding a porous spherical burner. The present paper demonstrates that by superimposing a spherical electrical field on such a flame, the flame remains spherical so that we can study the interaction between the electric field and flame in a one-dimensional fashion. Flames are susceptible to electric fields that are much weaker than the breakdown field of the flame gases owing to the presence of ions generated in the high temperature flame reaction zone. These ions and the electric current of the moving ions, in turn, significantly change the distribution of the electric field. Thus, to understand the interplay between the electric field and the flame is challenging. Numerous experimental studies of the effect of electric fields on flames have been reported. Unfortunately, they were all involved in complex geometries of both the flow field and the electric field, which hinders detailed study of the phenomena. In a one-dimensional domain, however, the electric field, the flow field, the thermal field and the chemical species field are all co-linear. Thus the problem is greatly simplified and becomes more tractable.

Mature vs. Active Deep-Seated Landslides: A Comparison Through Two Case Histories in the Alps

NASA Astrophysics Data System (ADS)

Delle Piane, Luca; Perello, Paolo; Baietto, Alessandro; Giorza, Alessandra; Musso, Alessia; Gabriele, Piercarlo; Baster, Ira

2016-06-01

Two case histories are presented, concerning the still poorly known alpine deep-seated gravitational slope deformations (DSD) located nearby Lanzada (central Italian Alps), and Sarre (north-western Italian Alps). The Lanzada DSD is a constantly monitored, juvenile, and active phenomenon, partly affecting an existing hydropower plant. Its well-developed landforms allow a precise field characterization of the instability-affected area. The Sarre DSD is a mature, strongly remodeled phenomenon, where the only hazard factor is represented by secondary instability processes at the base of the slope. In this case, the remodeling imposed the adoption of complementary analytical techniques to support the field work. The two presented studies had to be adapted to external factors, namely (a) available information, (b) geological and geomorphological setting, and (c) final scope of the work. The Lanzada case essentially relied upon accurate field work; the Sarre case was mostly based on digital image and DTM processing. In both cases a sound field structural analysis formed the necessary background to understand the mechanisms leading to instability. A back-analysis of the differences between the study methods adopted in the two cases is finally presented, leading to suggestions for further investigations and design.

Unconventional spin dynamics in the honeycomb-lattice material α - RuCl 3 : High-field electron spin resonance studies

DOE PAGES

Ponomaryov, A. N.; Schulze, E.; Wosnitza, J.; ...

2017-12-19

Here, we present high-field electron spin resonance (ESR) studies of the honeycomb-lattice material α-RuCl 3, a prime candidate to exhibit Kitaev physics. Two modes of antiferromagnetic resonance were detected in the zigzag ordered phase, with magnetic field applied in the a b plane. A very rich excitation spectrum was observed in the field-induced quantum paramagnetic phase. We compare the data obtained with the results of recent numerical calculations, strongly suggesting a very unconventional multiparticle character of the spin dynamics in α-RuCl 3. Finally, the frequency-field diagram of the lowest-energy ESR mode is found consistent with the behavior of the field-inducedmore » energy gap, revealed by thermodynamic measurements.« less

Magnetic field induced dynamical chaos.

PubMed

Ray, Somrita; Baura, Alendu; Bag, Bidhan Chandra

2013-12-01

In this article, we have studied the dynamics of a particle having charge in the presence of a magnetic field. The motion of the particle is confined in the x-y plane under a two dimensional nonlinear potential. We have shown that constant magnetic field induced dynamical chaos is possible even for a force which is derived from a simple potential. For a given strength of the magnetic field, initial position, and velocity of the particle, the dynamics may be regular, but it may become chaotic when the field is time dependent. Chaotic dynamics is very often if the field is time dependent. Origin of chaos has been explored using the Hamiltonian function of the dynamics in terms of action and angle variables. Applicability of the present study has been discussed with a few examples.

Unconventional spin dynamics in the honeycomb-lattice material α - RuCl 3 : High-field electron spin resonance studies

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

Ponomaryov, A. N.; Schulze, E.; Wosnitza, J.

Here, we present high-field electron spin resonance (ESR) studies of the honeycomb-lattice material α-RuCl 3, a prime candidate to exhibit Kitaev physics. Two modes of antiferromagnetic resonance were detected in the zigzag ordered phase, with magnetic field applied in the a b plane. A very rich excitation spectrum was observed in the field-induced quantum paramagnetic phase. We compare the data obtained with the results of recent numerical calculations, strongly suggesting a very unconventional multiparticle character of the spin dynamics in α-RuCl 3. Finally, the frequency-field diagram of the lowest-energy ESR mode is found consistent with the behavior of the field-inducedmore » energy gap, revealed by thermodynamic measurements.« less

Insight into the Li{sub 2}CO{sub 3}–K{sub 2}CO{sub 3} eutectic mixture from classical molecular dynamics: Thermodynamics, structure, and dynamics

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

Corradini, Dario; Vuilleumier, Rodolphe, E-mail: rodolphe.vuilleumier@ens.fr; Sorbonne Universités, UPMC Univ. Paris 06, PASTEUR, 75005 Paris

We use molecular dynamics simulations to study the thermodynamics, structure, and dynamics of the Li{sub 2}CO{sub 3}–K{sub 2}CO{sub 3} (62:38 mol. %) eutectic mixture. We present a new classical non-polarizable force field for this molten salt mixture, optimized using experimental and first principles molecular dynamics simulations data as reference. This simple force field allows efficient molecular simulations of phenomena at long time scales. We use this optimized force field to describe the behavior of the eutectic mixture in the 900–1100 K temperature range, at pressures between 0 and 5 GPa. After studying the equation of state in these thermodynamic conditions, wemore » present molecular insight into the structure and dynamics of the melt. In particular, we present an analysis of the temperature and pressure dependence of the eutectic mixture’s self-diffusion coefficients, viscosity, and ionic conductivity.« less

WFIRST: Project Overview and Status

NASA Astrophysics Data System (ADS)

Kruk, Jeffrey; WFIRST Formulation Science Working Group, WFIRST Project Team

2018-01-01

The Wide-Field InfraRed Survey Telescope (WFIRST) will be the next Astrophysics flagship mission to follow JWST. The observatory payload consists of a Hubble-size telescope aperture with a wide-field NIR instrument and a coronagraph operating at visible wavelengths and employing state-of-the-art wavefront sensing and control. The Wide-field instrument is optimized for large area NIR imaging and spectroscopic surveys, with performance requirements driven by programs to study cosmology and exoplanet detection via gravitational microlensing. All data will be public immediately, and a substantial guest observer program will be supported.The WFIRST Project is presently in Phase A, with a transition to Phase B expected in early to mid 2018. Candidate observing programs are under detailed study in order to inform the mission design, but the actual science investigations will not be selected until much closer to launch. We will present an overview of the present mission design and expected performance, a summary of Project status, and plans for selecting the observing programs.

Do we Need a Sociology of Energy Development?

NASA Astrophysics Data System (ADS)

Papatheodorou, Photini; Spathopoulos, Fivos

2016-04-01

The presentation discusses the need of developing a new area of scientific study, namely the "Sociology of Energy Development". It presents our knowledge gaps, regarding the reaction of societies towards energy projects. The presentation proposes that the first steps will be to study the "ethnography" of the energy companies and acquire a clear understanding of their specific cultures. In particular, the presentation argues for a need to raise meaningful questions about the values and attitudes of energy companies in areas such as environmental awareness; gender; cultural differences and other issues of conflict. It will also propose that a new conceptual framework is developed for the specific analysis of the relationship between society and energy companies, in the fields of public perception and trust. Finally, the presentation will conclude with an exploration of key principles, which may guide the development of new ethical practices in the field of energy.

Experimental studies of transonic flow field near a longitudinally slotted wind tunnel wall. Ph.D. Thesis - George Washington Univ., 1988

NASA Technical Reports Server (NTRS)

Everhart, Joel L.; Bobbitt, Percy J.

1994-01-01

The results of detailed parametric experiments are presented for the near-wall flow field of a longitudinally slotted transonic wind tunnel. Existing data are reevaluated and new data obtained in the Langley 6- by 19-inch Transonic Wind Tunnel are presented and analyzed. In the experiments, researchers systematically investigate many pertinent wall-geometry variables such as the wall openness and the number of slots along with the free stream Mach number and model angle of attack. Flow field surveys on the plane passing through the centerline of the slot were conducted and are presented. The effects of viscosity on the slot flow are considered in the analysis. The present experiments, combined with those of previous investigations, give a more complete physical characterization of the flow near and through the slotted wall of a transonic wind tunnel.

University of Washington Participation in SAFARI-2000

NASA Technical Reports Server (NTRS)

Hobbs, Peter V.

2005-01-01

This report presents a summary, of the participation in the 6-week field study in southern Africa. During the field study there were flown 119.02 research hours (31 research flights). In these flights the researchers obtained many unique data sets for evaluating the effects of biomass burning and other sources of particles and gases on the climate of southern Africa, and obtained simultaneous measurements with NASA ER-2 and Terra overflights. They also analyzed portions of the large data sets acquired in SAFARI-2000. They attended several SAFARI-2000 workshops, national and international conferences to present SAFARI-2000 results.

The Study of Talk between Teachers and Students, from the 1970s until the 2010s

ERIC Educational Resources Information Center

Mercer, Neil; Dawes, Lyn

2014-01-01

The close study of classroom talk has been an active field of research since the 1970s, when John Furlong made his significant contribution. Focusing particularly on research into teacher-student interactions, we will review the development of this field from the 1970s until the present, considering what has been learned and the educational…

Observer Role and Field Study Knowledge--An Essay Review of Usable Knowledge and SAFARI I.

ERIC Educational Resources Information Center

Smith, Louis M.; And Others

1981-01-01

A synthesis is presented of the work of Lindblom and Cohen, MacDonald and Walker, and the current authors. The synthesis considers issues in the usefulness of social science theory and research, and how observer roles in qualitative field studies yield multiple kinds of usable knowledge to a variety of audiences. (Author/BW)

The U.S. Role in International Disability Activities: A History and a Look towards the Future.

ERIC Educational Resources Information Center

Groce, Nora

This study presents an introduction to U.S. involvement in the field of international rehabilitation and disability. Oral history interviews were conducted with 21 "distinguished elders" in the field, an oral history conference with 18 of the elders was held and documented, and written sources were reviewed. The study includes: (1) a…

Comments on "Radiofrequency electromagnetic fields and some cancers of unknown etiology: An ecological study".

PubMed

Mortazavi, S A R; Mortazavi, Ghazal; Mortazavi, S M J

2017-12-31

This correspondence refers to the Science of the Total Environment article by Gonzalez-Rubio et al. entitled "Radiofrequency electromagnetic fields and some cancers of unknown etiology: An ecological study". Authors of this paper have presented the findings of their preliminary epidemiological study which combined epidemiology, statistics and geographical information systems (GIS). Gonzalez-Rubio et al. have analyzed the possible link between exposure to Radiofrequency Electromagnetic Fields (RF-EMF) in the city of Albacete, Spain and the incidence of cancers such as lymphomas, and brain tumors. The shortcomings of this study are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Hemispheric asymmetry of liking for representational and abstract paintings.

PubMed

Nadal, Marcos; Schiavi, Susanna; Cattaneo, Zaira

2017-10-13

Although the neural correlates of the appreciation of aesthetic qualities have been the target of much research in the past decade, few experiments have explored the hemispheric asymmetries in underlying processes. In this study, we used a divided visual field paradigm to test for hemispheric asymmetries in men and women's preference for abstract and representational artworks. Both male and female participants liked representational paintings more when presented in the right visual field, whereas preference for abstract paintings was unaffected by presentation hemifield. We hypothesize that this result reflects a facilitation of the sort of visual processes relevant to laypeople's liking for art-specifically, local processing of highly informative object features-when artworks are presented in the right visual field, given the left hemisphere's advantage in processing such features.

Ferromagnetic Objects Magnetovision Detection System.

PubMed

Nowicki, Michał; Szewczyk, Roman

2013-12-02

This paper presents the application of a weak magnetic fields magnetovision scanning system for detection of dangerous ferromagnetic objects. A measurement system was developed and built to study the magnetic field vector distributions. The measurements of the Earth's field distortions caused by various ferromagnetic objects were carried out. The ability for passive detection of hidden or buried dangerous objects and the determination of their location was demonstrated.

The Neural Basis of the Right Visual Field Advantage in Reading: An MEG Analysis Using Virtual Electrodes

ERIC Educational Resources Information Center

Barca, Laura; Cornelissen, Piers; Simpson, Michael; Urooj, Uzma; Woods, Will; Ellis, Andrew W.

2011-01-01

Right-handed participants respond more quickly and more accurately to written words presented in the right visual field (RVF) than in the left visual field (LVF). Previous attempts to identify the neural basis of the RVF advantage have had limited success. Experiment 1 was a behavioral study of lateralized word naming which established that the…

Evanescent fields of laser written waveguides

NASA Astrophysics Data System (ADS)

Jukić, Dario; Pohl, Thomas; Götte, Jörg B.

2015-03-01

We investigate the evanescent field at the surface of laser written waveguides. The waveguides are written by a direct femtosecond laser writing process into fused silica, which is then sanded down to expose the guiding layer. These waveguides support eigenmodes which have an evanescent field reaching into the vacuum above the waveguide. We study the governing wave equations and present solution for the fundamental eigenmodes of the modified waveguides.

The intensity of the ancient lunar field from magnetic studies on lunar samples

NASA Technical Reports Server (NTRS)

Stephenson, A.; Collinson, D. W.; Runchorn, S. K.

1977-01-01

Palaeointensity determination on Apollo 11, 16, and 17 rocks have indicated that from 3.9 to 4.0 AE ago the strength of the surface lunar magnetic field was about 1.3 Oe, while there is evidence from younger rocks that a field of about one quarter of this value was present at a later time (3.6 AE).

South American Field Experience: An Initiative in International Education. The Implementation Journal for the South American Field Experience.

ERIC Educational Resources Information Center

Martin, William J.

A description is provided of Williamsport Area Community College's (WACC's) South American Field Experience program, a travel/study program for faculty and staff designed to provide a variety of learning experiences through a three week trip to Peru, Chile, Argentina, and Brazil. Chapter I presents an overview of the development of the project,…

Field Study for Remote Sensing: An instructor's manual

NASA Technical Reports Server (NTRS)

Wake, W. H. (Editor); Hull, G. A. (Editor)

1981-01-01

The need for and value of field work (surface truthing) in the verification of image identification from high atitude infrared and multispectral space sensor images are discussed in this handbook which presents guidelines for developing instructional and research procedures in remote sensing of the environment.

LONG-TERM IMPACTS OF ORTHOPHOSPHATE TREATMENT ON COPPER LEVELS - PRESENTATION

EPA Science Inventory

Laboratory, pilot, and field data collected support the theoretical "cupric hydroxide" copper solubility model. For the short time frames inherent in laboratory and pilot studies of copper solubility and in initial field monitoring for the LCR from Tier 1 soldered copper sites, c...

New developments in the field of high voltage and extra-high voltage cables

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

Jocteur, R.

1990-04-01

In this paper, the author presents the developments in progress at the present time in France concerning the high voltage (HV) and extra-high voltage (EHV) cables with synthetic insulation and their accessories up to the 500 kV range. The authors have adopted a maximum operating field strength approaching 16 kV/mm (405 V/mil) for low density polyethylene (LDPE) insulated cables. The on-going studies should allow to bring the maximum operating field strength for crosslinked polyethylene (XLPE) insulation from 7 to 10 kV/mm (180 to 255 V/mil) and cables could be manufactured more economically with this material.

Ellington Field: A Short History, 1917-1963

NASA Technical Reports Server (NTRS)

Carlson, Erik D.

1999-01-01

My 1998 NASA/ASEE Summer Faculty Fellowship comprised two separate assignments: one to study the history of Ellington Field, the other to evaluate the Johnson Space Center Oral History Project (JSCOHP). This final report gives a summary of my article-length history of Ellington Field, from it inception as a U.S. Army training base to its present commercial/private status. This final report also presents my assessment of the methodology, administration, and continuing value of the JSCOHP, which is a series of recorded interviews with former and long-time JSC employees begun in 1997 to capture the experience of key participants in the human space program.

A sensor fusion field experiment in forest ecosystem dynamics

NASA Technical Reports Server (NTRS)

Smith, James A.; Ranson, K. Jon; Williams, Darrel L.; Levine, Elissa R.; Goltz, Stewart M.

1990-01-01

The background of the Forest Ecosystem Dynamics field campaign is presented, a progress report on the analysis of the collected data and related modeling activities is provided, and plans for future experiments at different points in the phenological cycle are outlined. The ecological overview of the study site is presented, and attention is focused on forest stands, needles, and atmospheric measurements. Sensor deployment and thermal and microwave observations are discussed, along with two examples of the optical radiation measurements obtained during the experiment in support of radiative transfer modeling. Future activities pertaining to an archival system, synthetic aperture radar, carbon acquisition modeling, and upcoming field experiments are considered.

Preliminary Findings from the One-Year Electric Field Study in the North Slope of Alaska (OYES-NSA), Atmospheric Radiation Measurement (ARM) Field Campaign

NASA Astrophysics Data System (ADS)

Lavigne, T.; Liu, C.

2017-12-01

Previous studies focusing on the comparison of the measured electric field to the physical properties of global electrified clouds have been conducted almost exclusively in the Southern Hemisphere. The One-Year Electric Field Study-North Slope of Alaska (OYES-NSA) aims to establish a long-running collection of this valuable electric field data in the Northern Hemisphere. Presented here is the six-month preliminary data and results of the OYES-NSA Atmospheric Radiation Mission (ARM) field campaign. The local electric field measured in Barrow, Alaska using two CS110 reciprocating shutter field meters, has been compared to simultaneous measurements from the ARM Ka-Band zenith radar, to better understand the influence and contribution of different types of clouds on the local electric field. The fair-weather electric field measured in Barrow has also been analyzed and compared to the climatology of electric field at Vostok Station, Antarctica. The combination of the electric field dataset in the Northern Hemisphere, alongside the local Ka cloud radar, global Precipitation Feature (PF) database, and quasi-global lightning activity (55oN-55oS), allows for advances in the physical understanding of the local electric field, as well as the Global Electric Circuit (GEC).

Simplified realistic human head model for simulating Tumor Treating Fields (TTFields).

PubMed

Wenger, Cornelia; Bomzon, Ze'ev; Salvador, Ricardo; Basser, Peter J; Miranda, Pedro C

2016-08-01

Tumor Treating Fields (TTFields) are alternating electric fields in the intermediate frequency range (100-300 kHz) of low-intensity (1-3 V/cm). TTFields are an anti-mitotic treatment against solid tumors, which are approved for Glioblastoma Multiforme (GBM) patients. These electric fields are induced non-invasively by transducer arrays placed directly on the patient's scalp. Cell culture experiments showed that treatment efficacy is dependent on the induced field intensity. In clinical practice, a software called NovoTalTM uses head measurements to estimate the optimal array placement to maximize the electric field delivery to the tumor. Computational studies predict an increase in the tumor's electric field strength when adapting transducer arrays to its location. Ideally, a personalized head model could be created for each patient, to calculate the electric field distribution for the specific situation. Thus, the optimal transducer layout could be inferred from field calculation rather than distance measurements. Nonetheless, creating realistic head models of patients is time-consuming and often needs user interaction, because automated image segmentation is prone to failure. This study presents a first approach to creating simplified head models consisting of convex hulls of the tissue layers. The model is able to account for anisotropic conductivity in the cortical tissues by using a tensor representation estimated from Diffusion Tensor Imaging. The induced electric field distribution is compared in the simplified and realistic head models. The average field intensities in the brain and tumor are generally slightly higher in the realistic head model, with a maximal ratio of 114% for a simplified model with reasonable layer thicknesses. Thus, the present pipeline is a fast and efficient means towards personalized head models with less complexity involved in characterizing tissue interfaces, while enabling accurate predictions of electric field distribution.

Hubbard pair cluster in the external fields. Studies of the magnetic properties

NASA Astrophysics Data System (ADS)

Balcerzak, T.; Szałowski, K.

2018-06-01

The magnetic properties of the two-site Hubbard cluster (dimer or pair), embedded in the external electric and magnetic fields and treated as the open system, are studied by means of the exact diagonalization of the Hamiltonian. The formalism of the grand canonical ensemble is adopted. The phase diagrams, on-site magnetizations, spin-spin correlations, mean occupation numbers and hopping energy are investigated and illustrated in figures. An influence of temperature, mean electron concentration, Coulomb U parameter and external fields on the quantities of interest is presented and discussed. In particular, the anomalous behaviour of the magnetization and correlation function vs. temperature near the critical magnetic field is found. Also, the effect of magnetization switching by the external fields is demonstrated.

Design of pulsed guiding magnetic field for high power microwave generators.

PubMed

Ju, J-C; Zhang, H; Zhang, J; Shu, T; Zhong, H-H

2014-09-01

In this paper, we present a comprehensive study on designing solenoid together with the corresponding power supply system to excite pulsed magnetic field required for high power microwave generators. Particularly, a solenoid is designed and the excited magnetic field is applied to a Ku-band overmoded Cerenkov generator. It is found in experiment that the electron beam is properly guided by the magnetic field and a 1.1 GW high power microwave is achieved at a central frequency of 13.76 GHz. Pulsed solenoid system has the advantages of compactness and low energy consumption, which are of great interest for repetitive operation. The reported studies and results can be generalized to other applications which require magnetic fields.

Analysis of the Radiated Field in an Electromagnetic Reverberation Chamber as an Upset-Inducing Stimulus for Digital Systems

NASA Technical Reports Server (NTRS)

Torres-Pomales, Wilfredo

2012-01-01

Preliminary data analysis for a physical fault injection experiment of a digital system exposed to High Intensity Radiated Fields (HIRF) in an electromagnetic reverberation chamber suggests a direct causal relation between the time profile of the field strength amplitude in the chamber and the severity of observed effects at the outputs of the radiated system. This report presents an analysis of the field strength modulation induced by the movement of the field stirrers in the reverberation chamber. The analysis is framed as a characterization of the discrete features of the field strength waveform responsible for the faults experienced by a radiated digital system. The results presented here will serve as a basis to refine the approach for a detailed analysis of HIRF-induced upsets observed during the radiation experiment. This work offers a novel perspective into the use of an electromagnetic reverberation chamber to generate upset-inducing stimuli for the study of fault effects in digital systems.

Decomposition of Magnetic Field Boundary Conditions into Parts Produced by Internal and External Sources

NASA Astrophysics Data System (ADS)

Lazanja, David; Boozer, Allen

2006-10-01

Given the total magnetic field on a toroidal plasma surface, a method for decomposing the field into a part due to internal currents (often the plasma) and a part due to external currents is presented. The method exploits Laplace theory which is valid in the vacuum region between the plasma surface and the chamber walls. The method is developed for the full three dimensional case which is necessary for studying stellarator plasma configurations. A change in the plasma shape is produced by the total normal field perturbation on the plasma surface. This method allows a separation of the total normal field perturbation into a part produced by external currents and a part produced by the plasma response. There are immediate applications to coil design. The computational procedure is based on Merkel's 1986 work on vacuum field computations. Several test cases are presented for toroidal surfaces which verify the method and computational robustness of the code.

The growth of Staphylococcus aureus and Escherichia coli in low-direct current electric fields.

PubMed

Zituni, Dunya; Schütt-Gerowitt, Heidi; Kopp, Marion; Krönke, Martin; Addicks, Klaus; Hoffmann, Christian; Hellmich, Martin; Faber, Franz; Niedermeier, Wilhelm

2014-03-01

Electrical potentials up to 800 mV can be observed between different metallic dental restorations. These potentials produce fields in the mouth that may interfere with microbial communities. The present study focuses on the impact of different electric field strengths (EFS) on the growth of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) in vitro. Cultures of S. aureus and E. coli in fluid and gel medium were exposed to different EFS. Effects were determined by calculation of viable counts and measurement of inhibition zones. In gel medium, anodic inhibition zones for S. aureus were larger than those for E. coli at all field strength levels. In fluid medium, the maximum decrease in the viable count of S. aureus cells was at 10 V⋅m(-1). Field-treated S. aureus cells presented ruptured cell walls and disintegrated cytoplasm. Conclusively, S. aureus is more sensitive to increasing electric field strength than E. coli.

CRUDE OIL BIOREMEDIATION: THE AMERICAN EXPERIENCE (PRESENTATION)

EPA Science Inventory

This is a state-of-the-art extended abstract presentation summary of the outputs from the oil spill program over the last 11 years. It summarizes the results of 3 field studies involving intentional releases of crude oil: the Delaware study in 1994 (sandy beach), the St. Lawrence...

The persistence of women in STEM: A constructivist grounded theory study

NASA Astrophysics Data System (ADS)

Gamm, Ryan

Men and women have reached relative parity in most sectors of the United States workforce. Yet women remain underrepresented in science, technology, engineering, and mathematics (STEM) fields (AAUW, 2010). Underrepresentation persists despite several decades of research, legislation, and intervention focused on gender equality in STEM fields (Clewell, 2002). The underrepresentation or shortage of women in STEM fields is identifiable primarily in degree attainment, in workforce demographics, and in a gender wage gap. Situated in constructivist grounded theory, this study asks how do women in science, technology, engineering, and mathematics (STEM) fields, particularly those in established career positions, persist when encountering personal and institutional barriers, resistance, and hostility? I use an interpretive-constructivist lens to conduct a grounded theory study exploring the experiences of women who persist in STEM fields, their relation to extant literature on this topic, and the connections to K-12 education practices, specifically curriculum. To understand the connections to curriculum I employ Pinar's (2012) method of currere. Pinar (2012) contends currere "provides a strategy for students of curriculum to study the relations between academic knowledge and life history in the interests of self-understanding and social reconstruction" (p.44). This qualitative study explored nine female STEM workers stories of persistence as each respondent works in STEM fields were gender parity has yet to be established. This study presents a substantive theory: As women persist in STEM fields they reframe themselves to be situated in the overlapping intersection of the social processes that correspond to "engagement" and "persistence." This reframing is possible by interpreting one's present day circumstances by independently removing oneself from current circumstances to understand the cumulative effect of both past and present. The findings highlight the importance of early educative experiences and their reinforcement throughout formal education including the STEM pipeline. The findings suggest that how one understands and interprets STEM work, and the compatibility ones' own identity with this work are crucial, reinforcing the some of the diverse body of literature that seeks to understand women's underrepresentation in STEM. Although literature focused on STEM related education, including work examining gender, offers suggestions compatible with the findings of this study, experiences that are match the stories of the respondents appear to be outside of the norm.

Aeronautical Sciences Advanced Studies Program. Delivery Order 0002: Plasma Modeling Program

DTIC Science & Technology

2009-04-01

reach the stagnation point of the airfoil. However, the effect is much more pronounced at the trailing edge region of the airfoil and its wake region...presents measured results that provide an indication of the amount of noise in the pitot probe measurements. The second presents the results of...is the noise problems that occurred in the measurements when a magnetic field was applied. For this reason the results with a magnetic field applied

Coherent manipulation of spontaneous emission spectra in coupled semiconductor quantum well structures.

PubMed

Chen, Aixi

2014-11-03

In triple coupled semiconductor quantum well structures (SQWs) interacting with a coherent driving filed, a coherent coupling field and a weak probe field, spontaneous emission spectra are investigated. Our studies show emission spectra can easily be manipulated through changing the intensity of the driving and coupling field, detuning of the driving field. Some interesting physical phenomena such as spectral-line enhancement/suppression, spectral-line narrowing and spontaneous emission quenching may be obtained in our system. The theoretical studies of spontaneous emission spectra in SQWS have potential application in high-precision spectroscopy. Our studies are based on the real physical system [Appl. Phys. Lett.86(20), 201112 (2005)], and this scheme might be realizable with presently available techniques.

Light field otoscope design for 3D in vivo imaging of the middle ear

PubMed Central

Bedard, Noah; Shope, Timothy; Hoberman, Alejandro; Haralam, Mary Ann; Shaikh, Nader; Kovačević, Jelena; Balram, Nikhil; Tošić, Ivana

2016-01-01

We present a light field digital otoscope designed to measure three-dimensional shape of the tympanic membrane. This paper describes the optical and anatomical considerations we used to develop the prototype, along with the simulation and experimental measurements of vignetting, field curvature, and lateral resolution. Using an experimental evaluation procedure, we have determined depth accuracy and depth precision of our system to be 0.05–0.07 mm and 0.21–0.44 mm, respectively. To demonstrate the application of our light field otoscope, we present the first three-dimensional reconstructions of tympanic membranes in normal and otitis media conditions, acquired from children who participated in a feasibility study at the Children’s Hospital of Pittsburgh of the University of Pittsburgh Medical Center. PMID:28101416

Numerical investigation of the spreading of self-excited stratified jets

NASA Technical Reports Server (NTRS)

Batcho, P. F.; Karniadakis, G. E.; Orszag, S. A.

1990-01-01

The structure and evolution of self-excited subsonic periodic arrays of jets of constant and variable density are studied using spectral-element direct numerical simulations. The governing equation of motion is presented, and a method based on spectral element discretizations appropriate for simulating arbitrarily complex geometry jets and large density variations for subsonic flows is developed. Variable density fields are found to be more unstable than the corresponding uniform density fields with much higher rms values; as a result, their spreading is also considerably larger. There is a dramatic increase in spreading after a few pairings occur. Findings presented for low and high side-momentum flux reveal a shifting of the origin of instability from the near-field to the far-field, respectively, and suggest possible routes of stabilization.

Distortion of Magnetic Fields in a Starless Core: Near-infrared Polarimetry of FeSt 1–457

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

Kandori, Ryo; Tamura, Motohide; Kusakabe, Nobuhiko

Magnetic fields are believed to play an important role in controlling the stability and contraction of the dense condensations of gas and dust that lead to the formation of stars and planetary systems. In the present study, the magnetic field of FeSt 1–457, a cold starless molecular cloud core, was mapped on the basis of the polarized near-infrared light from 185 background stars after being dichroically absorbed by dust aligned with the magnetic field in the core. A distinct “hourglass-shaped” magnetic field was identified in the region of the core, and was interpreted as the first evidence of a magneticmore » field structure distorted by mass condensation in a starless core. The steep curvature of the magnetic field lines obtained in the present study indicates that the distortion was mainly created during the formation phase of the dense core. The derived mass-to-magnetic flux ratio indicates that the core is in a magnetically supercritical state. However, the stability of the core can be considered to be in a nearly critical state if the additional contributions from the thermal and turbulent support are included. Further diffusion of the magnetic field and/or turbulent dissipation would cause the onset of the dynamical collapse of the core. The geometrical relationship between the direction of the magnetic field lines and the elongation of the core was found to be in good agreement with theoretical predictions for the formation of Sun-like stars under the influence of a magnetic field.« less

Domain wall dynamics driven by spin transfer torque and the spin-orbit field.

PubMed

Hayashi, Masamitsu; Nakatani, Yoshinobu; Fukami, Shunsuke; Yamanouchi, Michihiko; Mitani, Seiji; Ohno, Hideo

2012-01-18

We have studied current-driven dynamics of domain walls when an in-plane magnetic field is present in perpendicularly magnetized nanowires using an analytical model and micromagnetic simulations. We model an experimentally studied system, ultrathin magnetic nanowires with perpendicular anisotropy, where an effective in-plane magnetic field is developed when current is passed along the nanowire due to the Rashba-like spin-orbit coupling. Using a one-dimensional model of a domain wall together with micromagnetic simulations, we show that the existence of such in-plane magnetic fields can either lower or raise the threshold current needed to cause domain wall motion. In the presence of the in-plane field, the threshold current differs for positive and negative currents for a given wall chirality, and the wall motion becomes sensitive to out-of-plane magnetic fields. We show that large non-adiabatic spin torque can counteract the effect of the in-plane field.

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.

Student-guided field based investigations of microplastic contamination in urban waterways as a tool to introduce environmental science students to scientific inquiry

NASA Astrophysics Data System (ADS)

Pondell, C.

2016-12-01

Microplastic pollution is becoming an increasing concern in oceanographic and environmental studies, and offers an opportunity to engage undergraduate students in environmental research using a highly relevant field of investigation. For instance, a majority of environmental science majors not only know about the Great Pacific Garbage Patch, but can also list off several statistics about its size and impact on marine life. Building on this enthusiasm for understanding the impact of microplastics on the environment, a laboratory class was designed to introduce environmental science majors to the rigors of scientific investigation using microplastic pollution in urban waterways as the focus of their laboratory experience. Over a seven-week period, students worked in small groups to design an experiment, collect samples in the field, analyze the samples in the lab, and present their findings in a university-wide forum. Their research questions focused on developing a better understanding of the transportation and fate of microplastics in the urban waterways of Washington, D.C. This presentation will explore the benefits and challenges associated with a student guided field study for environmental science undergraduates, and will describe results and student feedback from their urban microplastic field study.

New type IIB backgrounds and aspects of their field theory duals

NASA Astrophysics Data System (ADS)

Caceres, Elena; Macpherson, Niall T.; Núñez, Carlos

2014-08-01

In this paper we study aspects of geometries in Type IIA and Type IIB String theory and elaborate on their field theory dual pairs. The backgrounds are associated with reductions to Type IIA of solutions with G 2 holonomy in eleven dimensions. We classify these backgrounds according to their G-structure, perform a non-Abelian T-duality on them and find new Type IIB configurations presenting dynamical SU(2)-structure. We study some aspects of the associated field theories defined by these new backgrounds. Various technical details are clearly spelled out.

Evaluating the effects of triclosan on 3 field crops grown in 4 formulations of biosolids.

PubMed

Shahmohamadloo, René S; Lissemore, Linda; Prosser, Ryan S; Sibley, Paul K

2017-07-01

A growing body of evidence suggests that amending soil with biosolids can be an integral component of sustainable agriculture. Despite strong evidence supporting its beneficial use in agriculture, there are concerns that chemicals, such as pharmaceuticals and personal care products, could present a risk to terrestrial ecosystems and human health. Triclosan is one of the most commonly detected compounds in biosolids. To date, laboratory studies indicate that triclosan likely poses a de minimis risk to field crops; however, these studies were either conducted under unrealistic exposure conditions or only assessed 1 or 2 formulations of biosolids. The purpose of the present study was to characterize the effects of triclosan on field crops in soils amended with 4 different formulations of biosolids (liquid, dewatered, compost, and alkaline-hydrolyzed), containing both background and spiked triclosan concentrations, following best management practices used in the province of Ontario. Three crop species (corn, soybean, and spring wheat) were evaluated using several plant growth endpoints (e.g., root wet mass, shoot length, shoot wet/dry mass) in 70-d to 90-d potted soil tests. The results indicated no adverse impact of triclosan on any crop-biosolids combination. Conversely, amending soil with biosolids either enhanced or had no negative effect, on the growth of plants. Results of the present study suggest little risk of triclosan to crops in agricultural fields amended with biosolids. Environ Toxicol Chem 2017;36:1896-1908. © 2016 SETAC. © 2016 SETAC.

Computational Studies of Magnetic Nozzle Performance

NASA Technical Reports Server (NTRS)

Ebersohn, Frans H.; Longmier, Benjamin W.; Sheehan, John P.; Shebalin, John B.; Raja, Laxminarayan

2013-01-01

An extensive literature review of magnetic nozzle research has been performed, examining previous work, as well as a review of fundamental principles. This has allow us to catalog all basic physical mechanisms which we believe underlie the thrust generation process. Energy conversion mechanisms include the approximate conservation of the magnetic moment adiabatic invariant, generalized hall and thermoelectric acceleration, swirl acceleration, thermal energy transformation into directed kinetic energy, and Joule heating. Momentum transfer results from the interaction of the applied magnetic field with currents induced in the plasma plume., while plasma detachment mechanisms include resistive diffusion, recombination and charge exchange collisions, magnetic reconnection, loss of adiabaticity, inertial forces, current closure, and self-field detachment. We have performed a preliminary study of Hall effects on magnetic nozzle jets with weak guiding magnetic fields and weak expansions (p(sub jet) approx. = P(sub background)). The conclusion from this study is that the Hall effect creates an azimuthal rotation of the plasma jet and, more generally, creates helical structures in the induced current, velocity field, and magnetic fields. We have studied plasma jet expansion to near vacuum without a guiding magnetic field, and are presently including a guiding magnetic field using a resistive MHD solver. This research is progressing toward the implementation of a full generalized Ohm's law solver. In our paper, we will summarize the basic principle, as well as the literature survey and briefly review our previous results. Our most recent results at the time of submittal will also be included. Efforts are currently underway to construct an experiment at the University of Michigan Plasmadynamics and Electric Propulsion Laboratory (PEPL) to study magnetic nozzle physics for a RF-thruster. Our computational study will work directly with this experiment to validate the numerical model, in order to study magnetic nozzle physics and optimize magnetic nozzle design. Preliminary results from the PEPL experiment will also be presented.

Reducing nutrient movement in manure-treated, tile-drained fields

USDA-ARS?s Scientific Manuscript database

Loss of nutrients from cropped soil represents an economic loss to producers and a threat to environmental quality. In this study, we monitored water, nutrient, and sediment in tile drainage from agricultural fields treated with manure in western Minnesota. Phosphorus results will be presented here....

Current and anticipated uses of the CATHARE code at EDF and FRAMATOME

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

Gandrille, J.L.; Vacher, J.L.; Poizat, F.

1997-07-01

This paper presents current industrial applications of the CATHARE code in the fields of Safety Studies and Simulators where the code is intensively used by FRAMATOME, EDF and CEA, the development partners of CATHARE. Future needs in these fields are also recapitulated.

Field measurements of diaphragm and top lateral members of three trapezoidal composite box girder bridges.

DOT National Transportation Integrated Search

2002-12-01

The results of field tests on three trapezoidal box girder bridges are presented. The study concentrated on the : measurement of the strains in the external and internal diaphragms and the top laterals of the boxes. The strains were : collected when ...

Automated pattern analysis: A newsilent partner in insect acoustic detection studies

USDA-ARS?s Scientific Manuscript database

This seminar reviews methods that have been developed for automated analysis of field-collected sounds used to estimate pest populations and guide insect pest management decisions. Several examples are presented of successful usage of acoustic technology to map insect distributions in field environ...

The Spitzer-IRAC/MIPS Extragalactic Survey (SIMES) in the South Ecliptic Pole Field

NASA Astrophysics Data System (ADS)

Baronchelli, I.; Scarlata, C.; Rodighiero, G.; Franceschini, A.; Capak, P. L.; Mei, S.; Vaccari, M.; Marchetti, L.; Hibon, P.; Sedgwick, C.; Pearson, C.; Serjeant, S.; Menéndez-Delmestre, K.; Salvato, M.; Malkan, M.; Teplitz, H. I.; Hayes, M.; Colbert, J.; Papovich, C.; Devlin, M.; Kovacs, A.; Scott, K. S.; Surace, J.; Kirkpatrick, J. D.; Atek, H.; Urrutia, T.; Scoville, N. Z.; Takeuchi, T. T.

2016-03-01

We present the Spitzer-IRAC/MIPS Extragalactic survey (SIMES) in the South Ecliptic Pole field. The large area covered (7.7 deg2), together with one of the lowest Galactic cirrus emissions in the entire sky and a very extensive coverage by Spitzer, Herschel, Akari, and GALEX, make the SIMES field ideal for extragalactic studies. The elongated geometry of the SIMES area (≈4:1), allowing for significant cosmic variance reduction, further improves the quality of statistical studies in this field. Here we present the reduction and photometric measurements of the Spitzer/IRAC data. The survey reaches depths of 1.93 and 1.75 μJy (1σ) at 3.6 and 4.5 μm, respectively. We discuss the multiwavelength IRAC-based catalog, completed with optical, mid-, and far-IR observations. We detect 341,000 sources with {F}3.6μ {{m}}≥slant 3σ . Of these, 10% have an associated 24 μm counterpart, while 2.7% have an associated SPIRE source. We release the catalog through the NASA/IPAC Infrared Science Archive. Two scientific applications of these IRAC data are presented in this paper. First, we compute integral number counts at 3.6 μm. Second, we use the [3.6]-[4.5] color index to identify galaxy clusters at z > 1.3. We select 27 clusters in the full area, a result consistent with previous studies at similar depth.

Vacuum fluctuations in an ancestor vacuum: A possible dark energy candidate

NASA Astrophysics Data System (ADS)

Aoki, Hajime; Iso, Satoshi; Lee, Da-Shin; Sekino, Yasuhiro; Yeh, Chen-Pin

2018-02-01

We consider an open universe created by bubble nucleation, and study possible effects of our "ancestor vacuum," a de Sitter space in which bubble nucleation occurred, on the present universe. We compute vacuum expectation values of the energy-momentum tensor for a minimally coupled scalar field, carefully taking into account the effect of the ancestor vacuum by the Euclidean prescription. We pay particular attention to the so-called supercurvature mode, a non-normalizable mode on a spatial slice of the open universe, which has been known to exist for sufficiently light fields. This mode decays in time most slowly, and may leave residual effects of the ancestor vacuum, potentially observable in the present universe. We point out that the vacuum energy of the quantum field can be regarded as dark energy if mass of the field is of order the present Hubble parameter or smaller. We obtain preliminary results for the dark energy equation of state w (z ) as a function of the redshift.

Molecular dynamics simulations for mechanical properties of borophene: parameterization of valence force field model and Stillinger-Weber potential

PubMed Central

Zhou, Yu-Ping; Jiang, Jin-Wu

2017-01-01

While most existing theoretical studies on the borophene are based on first-principles calculations, the present work presents molecular dynamics simulations for the lattice dynamical and mechanical properties in borophene. The obtained mechanical quantities are in good agreement with previous first-principles calculations. The key ingredients for these molecular dynamics simulations are the two efficient empirical potentials developed in the present work for the interaction of borophene with low-energy triangular structure. The first one is the valence force field model, which is developed with the assistance of the phonon dispersion of borophene. The valence force field model is a linear potential, so it is rather efficient for the calculation of linear quantities in borophene. The second one is the Stillinger-Weber potential, whose parameters are derived based on the valence force field model. The Stillinger-Weber potential is applicable in molecular dynamics simulations of nonlinear physical or mechanical quantities in borophene. PMID:28349983

Neoclassical simulation of tokamak plasmas using the continuum gyrokinetic code TEMPEST.

PubMed

Xu, X Q

2008-07-01

We present gyrokinetic neoclassical simulations of tokamak plasmas with a self-consistent electric field using a fully nonlinear (full- f ) continuum code TEMPEST in a circular geometry. A set of gyrokinetic equations are discretized on a five-dimensional computational grid in phase space. The present implementation is a method of lines approach where the phase-space derivatives are discretized with finite differences, and implicit backward differencing formulas are used to advance the system in time. The fully nonlinear Boltzmann model is used for electrons. The neoclassical electric field is obtained by solving the gyrokinetic Poisson equation with self-consistent poloidal variation. With a four-dimensional (psi,theta,micro) version of the TEMPEST code, we compute the radial particle and heat fluxes, the geodesic-acoustic mode, and the development of the neoclassical electric field, which we compare with neoclassical theory using a Lorentz collision model. The present work provides a numerical scheme for self-consistently studying important dynamical aspects of neoclassical transport and electric field in toroidal magnetic fusion devices.

Neoclassical simulation of tokamak plasmas using the continuum gyrokinetic code TEMPEST

NASA Astrophysics Data System (ADS)

Xu, X. Q.

2008-07-01

We present gyrokinetic neoclassical simulations of tokamak plasmas with a self-consistent electric field using a fully nonlinear (full- f ) continuum code TEMPEST in a circular geometry. A set of gyrokinetic equations are discretized on a five-dimensional computational grid in phase space. The present implementation is a method of lines approach where the phase-space derivatives are discretized with finite differences, and implicit backward differencing formulas are used to advance the system in time. The fully nonlinear Boltzmann model is used for electrons. The neoclassical electric field is obtained by solving the gyrokinetic Poisson equation with self-consistent poloidal variation. With a four-dimensional (ψ,θ,γ,μ) version of the TEMPEST code, we compute the radial particle and heat fluxes, the geodesic-acoustic mode, and the development of the neoclassical electric field, which we compare with neoclassical theory using a Lorentz collision model. The present work provides a numerical scheme for self-consistently studying important dynamical aspects of neoclassical transport and electric field in toroidal magnetic fusion devices.

Electric field measurement in the dielectric tube of helium atmospheric pressure plasma jet

NASA Astrophysics Data System (ADS)

Sretenović, Goran B.; Guaitella, Olivier; Sobota, Ana; Krstić, Ivan B.; Kovačević, Vesna V.; Obradović, Bratislav M.; Kuraica, Milorad M.

2017-03-01

The results of the electric field measurements in the capillary of the helium plasma jet are presented in this article. Distributions of the electric field for the streamers are determined for different gas flow rates. It is found that electric field strength in front of the ionization wave decreases as it approaches to the exit of the tube. The values obtained under presented experimental conditions are in the range of 5-11 kV/cm. It was found that the increase in gas flow above 1500 SCCM could induce substantial changes in the discharge operation. This is reflected through the formation of the brighter discharge region and appearance of the electric field maxima. Furthermore, using the measured values of the electric field strength in the streamer head, it was possible to estimate electron densities in the streamer channel. Maximal density of 4 × 1011 cm-3 is obtained in the vicinity of the grounded ring electrode. Similar behaviors of the electron density distributions to the distributions of the electric field strength are found under the studied experimental conditions.

Beyond 2D: Parallel Electric Fields and Dissipation in Guide Field Reconnectio

NASA Astrophysics Data System (ADS)

Wilder, F. D.; Ergun, R.; Ahmadi, N.; Goodrich, K.; Eriksson, S.; Shimoda, E.; Burch, J. L.; Phan, T.; Torbert, R. B.; Strangeway, R. J.; Giles, B. L.; Lindqvist, P. A.; Khotyaintsev, Y. V.

2017-12-01

In 2015, NASA launched the Magnetospheric Multiscale (MMS) mission to study phenomenon of magnetic reconnection down to the electron scale. Advantages of MMS include a 20s spin period and long axial booms, which together allow for measurement of 3-D electric fields with accuracy down to 1 mV/m. During the two dayside phases of the prime mission, MMS has observed multiple electron and ion diffusion region events at the Earth's subsolar and flank magnetopause, as well as in the magnetosheath, providing an option to study both symmetric and asymmetric reconnection at a variety of guide field strengths. We present a review of parallel electric fields observed by MMS during diffusion region events, and discuss their implications for simulations and laboratory observations of reconnection. We find that as the guide field increases, the dissipation in the diffusion region transitions from being due to currents and fields perpendicular to the background magnetic field, to being associated with parallel electric fields and currents. Additionally, the observed parallel electric fields are significantly larger than those predicted by simulations of reconnection under strong guide field conditions.

Spin polarization transfer mechanisms of SABRE: A magnetic field dependent study.

PubMed

Pravdivtsev, Andrey N; Ivanov, Konstantin L; Yurkovskaya, Alexandra V; Petrov, Pavel A; Limbach, Hans-Heinrich; Kaptein, Robert; Vieth, Hans-Martin

2015-12-01

We have investigated the magnetic field dependence of Signal Amplification By Reversible Exchange (SABRE) arising from binding of para-hydrogen (p-H2) and a substrate to a suitable transition metal complex. The magnetic field dependence of the amplification of the (1)H Nuclear Magnetic Resonance (NMR) signals of the released substrates and dihydrogen, and the transient transition metal dihydride species shows characteristic patterns, which is explained using the theory presented here. The generation of SABRE is most efficient at low magnetic fields due to coherent spin mixing at nuclear spin Level Anti-Crossings (LACs) in the SABRE complexes. We studied two Ir-complexes and have shown that the presence of a (31)P atom in the SABRE complex doubles the number of LACs and, consequently, the number of peaks in the SABRE field dependence. Interestingly, the polarization of SABRE substrates is always accompanied by the para-to-ortho conversion in dihydride species that results in enhancement of the NMR signal of free (H2) and catalyst-bound H2 (Ir-HH). The field dependences of hyperpolarized H2 and Ir-HH by means of SABRE are studied here, for the first time, in detail. The field dependences depend on the chemical shifts and coupling constants of Ir-HH, in which the polarization transfer takes place. A negative coupling constant of -7Hz between the two chemically equivalent but magnetically inequivalent hydride nuclei is determined, which indicates that Ir-HH is a dihydride with an HH distance larger than 2Å. Finally, the field dependence of SABRE at high fields as found earlier has been investigated and attributed to polarization transfer to the substrate by cross-relaxation. The present study provides further evidence for the key role of LACs in the formation of SABRE-derived polarization. Understanding the spin dynamics behind the SABRE method opens the way to optimizing its performance and overcoming the main limitation of NMR, its notoriously low sensitivity. Copyright © 2015 Elsevier Inc. All rights reserved.

Spin polarization transfer mechanisms of SABRE: A magnetic field dependent study

NASA Astrophysics Data System (ADS)

Pravdivtsev, Andrey N.; Ivanov, Konstantin L.; Yurkovskaya, Alexandra V.; Petrov, Pavel A.; Limbach, Hans-Heinrich; Kaptein, Robert; Vieth, Hans-Martin

2015-12-01

We have investigated the magnetic field dependence of Signal Amplification By Reversible Exchange (SABRE) arising from binding of para-hydrogen (p-H2) and a substrate to a suitable transition metal complex. The magnetic field dependence of the amplification of the 1H Nuclear Magnetic Resonance (NMR) signals of the released substrates and dihydrogen, and the transient transition metal dihydride species shows characteristic patterns, which is explained using the theory presented here. The generation of SABRE is most efficient at low magnetic fields due to coherent spin mixing at nuclear spin Level Anti-Crossings (LACs) in the SABRE complexes. We studied two Ir-complexes and have shown that the presence of a 31P atom in the SABRE complex doubles the number of LACs and, consequently, the number of peaks in the SABRE field dependence. Interestingly, the polarization of SABRE substrates is always accompanied by the para-to-ortho conversion in dihydride species that results in enhancement of the NMR signal of free (H2) and catalyst-bound H2 (Ir-HH). The field dependences of hyperpolarized H2 and Ir-HH by means of SABRE are studied here, for the first time, in detail. The field dependences depend on the chemical shifts and coupling constants of Ir-HH, in which the polarization transfer takes place. A negative coupling constant of -7 Hz between the two chemically equivalent but magnetically inequivalent hydride nuclei is determined, which indicates that Ir-HH is a dihydride with an HH distance larger than 2 Å. Finally, the field dependence of SABRE at high fields as found earlier has been investigated and attributed to polarization transfer to the substrate by cross-relaxation. The present study provides further evidence for the key role of LACs in the formation of SABRE-derived polarization. Understanding the spin dynamics behind the SABRE method opens the way to optimizing its performance and overcoming the main limitation of NMR, its notoriously low sensitivity.

Older Adults' Memory for Verbally Presented Medical Information

ERIC Educational Resources Information Center

Bankoff, Sarah M.; Sandberg, Elisabeth Hollister

2012-01-01

Previous research demonstrates that patients typically have difficulty remembering information presented during healthcare consultations. This study examined how older adults learn and remember verbally presented medical information. Healthy older adults were tested for recall in experimental and field settings. Participants viewed a five-minute…

A Study of Reconnection Poleward of Cusp: Cluster and Polar

NASA Astrophysics Data System (ADS)

Muzamil, Fathima

Asymmetries in plasma density and the presence of a guide field significantly alter the structure of the ion diffusion region (IDR) in symmetric, collisionless reconnection. These features have been shown by numerical simulations under moderate density asymmetries ( 10), and theoretical analyses. However, very few studies have addressed these issues with in-situ observations, particularly at high magnetic latitudes. By the structure of the IDR we refer to features such as the non-colocation of the X-line and stagnation line, the distortion of the Hall magnetic and electric fields, outflow speed, outflow density etc. We have compiled a collection of Cluster crossings of the high-latitude magnetopause poleward of the cusp under northward interplanetary magnetic field in the years 2001-2008. We identified 18 events that fulfilled the criteria that was used as plausible evidence for an IDR crossing. A wide range of guide fields (6 to 74%) and very high density asymmetries (over three orders of magnitude) were present in this event list. The total DC electric field ranged from 10 mV/m-72 mV/m. We compared theoretical predictions for ion outflow speed and density against measured values for events with least magnetic shear and found good agreement. Peak values of both measured quantities agreed better than the average values. The separation between the X and S-lines were measured for two events. The separation was in the order of 2 ion inertial lengths. We presented a detailed analysis of a current sheet crossing hallmarked by a density asymmetry of 2 orders of magnitude ( 140) [Muzamil et al., 2014, JGR]. This event was measured by the Polar spacecraft, also at high latitudes poleward of the cusp. Data agreed well with simulation results, especially the observation of density cavities together with isolated electric fields in the normal direction at both separatrices. This has not been observed in previous observational studies. Effect of the guide field on both sides of the X-line was examined using two events with jet reversals and similar guide fields. A sunward-tailward asymmetry in the Hall magnetic field structure was observed due to the guide field in the two outflow regions. The Hall field was weakened and changed polarity in the vicinity of the X-line due to an electron velocity shear layer. Using three other crossings with high guide fields, we measured a 40-60% enhancement in the Hall magnetic field showing consistency with simulations. We then presented a case study of large episodic magnetic field depressions in the magnetosheath boundary layer region near the magnetic separatrix. We identified specific characteristics and compared them to possible generating mechanisms. The most plausible one was kinetic Alfven waves. Thus, we have provided observational evidence for the structure of the IDR in poleward of the cusp under several different asymmetric conditions and guide fields.

Influence of the mode of deformation on recrystallisation behaviour of titanium through experiments, mean field theory and phase field model

NASA Astrophysics Data System (ADS)

Athreya, C. N.; Mukilventhan, A.; Suwas, Satyam; Vedantam, Srikanth; Subramanya Sarma, V.

2018-04-01

The influence of the mode of deformation on recrystallisation behaviour of Ti was studied by experiments and modelling. Ti samples were deformed through torsion and rolling to the same equivalent strain of 0.5. The deformed samples were annealed at different temperatures for different time durations and the recrystallisation kinetics were compared. Recrystallisation is found to be faster in the rolled samples compared to the torsion deformed samples. This is attributed to the differences in stored energy and number of nuclei per unit area in the two modes of deformation. Considering decay in stored energy during recrystallisation, the grain boundary mobility was estimated through a mean field model. The activation energy for recrystallisation obtained from experiments matched with the activation energy for grain boundary migration obtained from mobility calculation. A multi-phase field model (with mobility estimated from the mean field model as a constitutive input) was used to simulate the kinetics, microstructure and texture evolution. The recrystallisation kinetics and grain size distributions obtained from experiments matched reasonably well with the phase field simulations. The recrystallisation texture predicted through phase field simulations compares well with experiments though few additional texture components are present in simulations. This is attributed to the anisotropy in grain boundary mobility, which is not accounted for in the present study.

Preliminary study of injection transients in the TPS storage ring

NASA Astrophysics Data System (ADS)

Chen, C. H.; Liu, Y. C.; Y Chen, J.; Chiu, M. S.; Tseng, F. H.; Fann, S.; Liang, C. C.; Huang, C. S.; Y Lee, T.; Y Chen, B.; Tsai, H. J.; Luo, G. H.; Kuo, C. C.

2017-07-01

An optimized injection efficiency is related to a perfect match between the pulsed magnetic fields in the storage ring and transfer line extraction in the TPS. However, misalignment errors, hardware output errors and leakage fields are unavoidable. We study the influence of injection transients on the stored TPS beam and discuss solutions to compensate these. Related simulations and measurements will be presented.

Synthesis of regional wildlife and vegetation field studies to guide management of standing and down dead trees

Treesearch

Bruce G. Marcot; Janet L. Ohmann; Kim L. Mellen-McLean; Karen L. Waddell

2010-01-01

We used novel methods for combining information from wildlife and vegetation field studies to develop guidelines for managing dead wood for wildlife and biodiversity. The DecAID Decayed Wood Adviser presents data on wildlife use of standing and down dead trees (snags and down wood) and summaries of regional vegetation plot data depicting dead wood conditions, for...

Acceptability of the Conceptions of Higher Education Quality to First Year Students of the Study Field of Pedagogy

ERIC Educational Resources Information Center

Žibeniene, Gintaute; Savickiene, Izabela

2014-01-01

The article presents which conceptions of higher education quality are most acceptable to first-year students of the study field of pedagogy. It is significant to analyse students' opinions as more than 10 years ago the EU member states agreed that higher education institutions bear responsibility for the quality of higher education. Being members…

SERS internship Spring 1995 abstracts and research papers

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

Davis, B.

Presented topics varied over many fields in science and engineering. Botany on grasses in California, real time face recognition technology, thermogravimetric studies on corrosion and finite element modeling of the human pelvis are examples of discussed subjects. Further fields of study are carcinogenics, waste management, radar imaging, automobile accessories, document searching on the internet, and shooting stars. Individual papers are indexed separately on EDB.

Analytical and numerical study of New field emitter processing for superconducting cavities

NASA Astrophysics Data System (ADS)

Volkov, Vladimir; Petrov, Victor

2018-02-01

In this article a scientific prove for a new technology to maximize the accelerating gradient in superconducting cavities by processing on higher order mode frequencies is presented. As dominant energy source the heating of field emitters by an induced rf current (rf-heating) is considered. The field emitter structure is assumed to be a chain of conductive particles, which are formed by attractive forces.

Gravity field information from Gravity Probe-B

NASA Technical Reports Server (NTRS)

Smith, D. E.; Lerch, F. J.; Colombo, O. L.; Everitt, C. W. F.

1989-01-01

The Gravity Probe-B Mission will carry the Stanford Gyroscope relativity experiment into orbit in the mid 1990's, as well as a Global Positioning System (GPS) receiver whose tracking data will be used to study the earth gravity field. Estimates of the likely quality of a gravity field model to be derived from the GPS data are presented, and the significance of this experiment to geodesy and geophysics are discussed.

Study of free-piston Stirling engine driven linear alternators

NASA Technical Reports Server (NTRS)

Nasar, S. A.; Chen, C.

1987-01-01

The analysis, design and operation of single phase, single slot tubular permanent magnet linear alternator is presented. Included is the no-load and on-load magnetic field investigation, permanent magnet's leakage field analysis, parameter identification, design guidelines and an optimal design of a permanent magnet linear alternator. For analysis of the magnetic field, a simplified magnetic circuit is utilized. The analysis accounts for saturation, leakage and armature reaction.

Polarized radiation diagnostics of stellar magnetic fields

NASA Astrophysics Data System (ADS)

Mathys, Gautier

The main techniques used to diagnose magnetic fields in stars from polarimetric observations are presented. First, a summary of the physics of spectral line formation in the presence of a magnetic field is given. Departures from the simple case of linear Zeeman effect are briefly considered: partial Paschen-Back effect, contribution of hyperfine structure, and combined Stark and Zeeman effects. Important approximate solutions of the equation of transfer of polarized light in spectral lines are introduced. The procedure for disk-integration of emergent Stokes profiles, which is central to stellar magnetic field studies, is described, with special attention to the treatment of stellar rotation. This formalism is used to discuss the determination of the mean longitudinal magnetic field (through the photographic technique and through Balmer line photopolarimetry). This is done within the specific framework of Ap stars, which, with their unique large-scale organized magnetic fields, are an ideal laboratory for studies of stellar magnetism. Special attention is paid to those Ap stars whose magnetically split line components are resolved in high-dispersion Stokes I spectra, and to the determination of their mean magnetic field modulus. Various techniques of exploitation of the information contained in polarized spectral line profiles are reviewed: the moment technique (in particular, the determination of the crossover and of the mean quadratic field), Zeeman-Doppler imaging, and least-squares deconvolution. The prospects that these methods open for linear polarization studies are sketched. The way in which linear polarization diagnostics complement their Stokes I and V counterparts is emphasized by consideration of the results of broad band linear polarization measurements. Illustrations of the use of various diagnostics to derive properties of the magnetic fields of Ap stars are given. This is used to show the interest of deriving more physically realistic models of the geometric structure of these fields. How this can possibly be achieved is briefly discussed. An overview of the current status of polarimetric studies of magnetic fields in non-degenerate stars of other types is presented. The final section is devoted to magnetic fields of white dwarfs. Current knowledge of magnetic fields of isolated white dwarfs is briefly reviewed. Diagnostic techniques are discussed, with particular emphasis on the variety of physical processes to be considered for understanding of spectral line formation over the broad range of magnetic field strengths encountered in these stars.

Magnetic fields in giant planet formation and protoplanetary discs

NASA Astrophysics Data System (ADS)

Keith, Sarah Louise

2015-12-01

Protoplanetary discs channel accretion onto their host star. How this is achieved is critical to the growth of giant planets which capture their massive gaseous atmosphere from the surrounding flow. Theoretical studies find that an embedded magnetic field could power accretion by hydromagnetic turbulence or torques from a large-scale field. This thesis presents a study of the inuence of magnetic fields in three key aspects of this process: circumplanetary disc accretion, gas flow across gaps in protoplanetary discs, and magnetic-braking in accretion discs. The first study examines the conditions needed for self-consistent accretion driven by magnetic fields or gravitational instability. Models of these discs typically rely on hydromagnetic turbulence as the source of effective viscosity. However, magnetically coupled,accreting regions may be so limited that the disc may not support sufficient inflow. An improved Shakura-Sunyaev ? disc is used to calculate the ionisation fraction and strength of non-ideal effects. Steady magnetically-driven accretion is limited to the thermally ionised, inner disc so that accretion in the remainder of the disc is time-dependent. The second study addresses magnetic flux transport in an accretion gap evacuated by a giant planet. Assuming the field is passively drawn along with the gas, the hydrodynamical simulation of Tanigawa, Ohtsuki & Machida (2012) is used for an a posteriori analysis of the gap field structure. This is used to post-calculate magnetohydrodynamical quantities. This assumption is self-consistent as magnetic forces are found to be weak, and good magnetic coupling ensures the field is frozen into the gas. Hall drift dominates across much of the gap, with the potential to facilitate turbulence and modify the toroidal field according to the global field orientation. The third study considers the structure and stability of magnetically-braked accretion discs. Strong evidence for MRI dead-zones has renewed interest in accretion powered by large-scale fields. An equilibrium model is presented for the radial structure of an axisymmetric, magnetically-braked accretion disc connected to a force-free external field. The accretion rate is multivalued at protoplanetary disc column densities, featuring an `S-curve' associated with models of accretion outbursting. A local, linear analysis of the stability of radial modes finds that the rapidly accreting, middle and upper solution branches are unstable, further highlighting the potential for eruptive accretion events.

Normal Gravity Fields and Equipotential Ellipsoids of Small Objects in the Solar System: A Closed-form Solution in Ellipsoidal Harmonics up to the Second Degree

NASA Astrophysics Data System (ADS)

Hu, Xuanyu

2017-11-01

We propose a definition for the normal gravity fields and normal figures of small objects in the solar system, such as asteroids, cometary nuclei, and planetary moons. Their gravity fields are represented as series of ellipsoidal harmonics, ensuring more robust field evaluation in the proximity of an arbitrary, convex shape than using spherical harmonics. The normal gravity field, approximate to the actual field, can be described by a finite series of three terms, that is, degree zero, and the zonal and sectoral harmonics of degree two. The normal gravity is that of an equipotential ellipsoid, defined as the normal ellipsoid of the body. The normal ellipsoid may be distinct from the actual figure. We present a rationale for specifying and a numerical method for determining the parameters of the normal ellipsoid. The definition presented here generalizes the convention of the normal spheroid of a large, hydrostatically equilibrated planet, such as Earth. Modeling the normal gravity and the normal ellipsoid is relevant to studying the formation of the “rubble pile” objects, which may have been accreted, or reorganized after disruption, under self-gravitation. While the proposed methodology applies to convex, approximately ellipsoidal objects, those bi-lobed objects can be treated as contact binaries comprising individual convex subunits. We study an exemplary case of the nearly ellipsoidal Martian moon, Phobos, subject to strong tidal influence in its present orbit around Mars. The results allude to the formation of Phobos via gravitational accretion at some further distance from Mars.

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.

Two-dimensional electrodynamic structure of the normal glow discharge in an axial magnetic field

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

Surzhikov, S. T., E-mail: surg@ipmnet.ru

Results are presented from numerical simulations of an axisymmetric normal glow discharge in molecular hydrogen and molecular nitrogen in an axial magnetic field. The charged particle densities and averaged azimuthal rotation velocities of electrons and ions are studied as functions of the gas pressure in the range of 1–5 Torr, electric field strength in the range of 100–600 V/cm, and magnetic field in the range of 0.01–0.3 T. It is found that the axial magnetic field does not disturb the normal current density law.

Field Testing of High Degree Revenue Service Track for Buckling Safety Assessment

DOT National Transportation Integrated Search

1995-01-01

This report presents the results of a field study of high degree curves in continuous welded rail (CWR) territory. This program was conducted at two test sites: a 10 degree curve on the Atchison, Topeka, and Santa Fe (ATSF) Railroad near Sante Fe, NM...

Collegiate Grading Practices and the Gender Pay Gap.

ERIC Educational Resources Information Center

Dowd, Alicia C.

2000-01-01

Presents a theoretical analysis showing that relatively low grading quantitative fields and high grading verbal fields create a disincentive for college women to invest in quantitative study. Extends research by R. Sabot and J. Wakeman-Linn. Models pressures on grading practices using higher education production functions. (Author/SLD)

Biology Division annual progress report for period ending December 31, 1968

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

None

1969-07-01

Brief summaries are presented of research in progress in the fields of radiobiology, genetics, hematology, immunology, physsiology, biochemistry, bacteriology, enzymology, microbiology, photosynthesis, biophysics, radiation protection, and related fields. A list is included of 212 publications in the world literature that report results of completed studies. (CH)

Influence of magnetic fields on the color screening masses

NASA Astrophysics Data System (ADS)

Bonati, Claudio; D'Elia, Massimo; Mesiti, Michele; Negro, Francesco; Rucci, Andrea; Sanfilippo, Francesco

2018-03-01

We present some recent results obtained in the study of the color magnetic and electric screening masses in the QCD plasma. In particular, we discuss how the masses get modified by strong external fields which are expected to be created in physical situations such as heavy-ion collisions.

A Field-Based Technique for Teaching about Habitat Fragmentation and Edge Effects

ERIC Educational Resources Information Center

Resler, Lynn M.; Kolivras, Korine N.

2009-01-01

This article presents a field technique that exposes students to the indirect effects of habitat fragmentation on plant distributions through studying edge effects. This assignment, suited for students in an introductory biogeography or resource geography class, increases students' knowledge of basic biogeographic concepts such as environmental…

Self-Paced Physics, Segments 32-36.

ERIC Educational Resources Information Center

New York Inst. of Tech., Old Westbury.

Five study segments of the Self-Paced Physics Course materials are presented in this seventh problems and solutions book used as a part of student course work. The content is related to magnetic fields, magnetic moments, forces on charged particles in magnetic fields, electron volts, cyclotron, electronic charge to mass ratio, current-carrying…

A preliminary geomorphological map from the Múlajökull drumlin field, Iceland

NASA Astrophysics Data System (ADS)

Jonsson, S. A.; Schomacker, A.; Benediktsson; Johnson, M.; Ingolfsson, O.

2012-12-01

The drumlin field in front of Múlajökull, a surge-type, outlet glacier from Hofsjökull in Iceland, is the only known active drumlin field (Johnson et al., 2010). The aim of this study is to further explore the distribution and formation of drumlins and drumlin fields in a modern glacial environment. We use data from Digital Elevation Models (DEMs), aerial imagery and field mapping. Here we present a preliminary geomorphological map based on remote sensing and fieldwork in 2010 and 2011. Geomorphological mapping of the drumlin field both with DEMs and ground proofing has revealed over 100 drumlins and a number of drumlinized ridges. The drumlins furthest from the present ice margin are broader and have lower relief than those closer to the ice. We suggest that this reflects an evolution of the drumlin form during recurrent surging. The drumlins farther away from the ice have experienced fewer surges than those that have just been uncovered due to present retreat of the ice margin. During successive surges, the drumlins become narrower and develop a higher relief. Reference: Johnson, M.D., Schomacker, A., Benediktsson, Í. Ö., Geiger, A. J., Ferguson, A. and Ingólfsson, Ó. 2010, Active drumlin field revealed at the margin of Múlajökull, Iceland: A surge-type glacier: Geology v. 38, p. 943-946.

Some new results on charged compact boson stars

DOE PAGES

Kumar, Sanjeev; Kulshreshtha, Usha; Kulshreshtha, Daya Shankar; ...

2017-07-21

In this work we present some new results obtained in a study of the phase diagram of charged compact boson stars in a theory involving a complex scalar field with a conical potential coupled to a U(1) gauge field and gravity. We here obtain new bifurcation points in this model. We present a detailed discussion of the various regions of the phase diagram with respect to the bifurcation points. The theory is seen to contain rich physics in a particular domain of the phase diagram.

[Electormagnetic field of the mobile phone base station: case study].

PubMed

Bieńkowski, Paweł; Zubrzak, Bartłomiej; Surma, Robert

2011-01-01

The paper presents changes in the electromagnetic field intensity in a school building and its surrounding after the mobile phone base station installation on the roof of the school. The comparison of EMF intensity measured before the base station was launched (electromagnetic background measurement) and after starting its operation (two independent control measurements) is discussed. Analyses of measurements are presented and the authors also propose the method of the electromagnetic field distribution adjustment in the area of radiation antennas side lobe to reduce the intensity of the EMF level in the base station proximity. The presented method involves the regulation of the inclination. On the basis of the measurements, it was found that the EMF intensity increased in the building and its surroundings, but the values measured with wide margins meet the requirements of the Polish law on environmental protection.

Light effects on the multicellular magnetotactic prokaryote 'Candidatus Magnetoglobus multicellularis' are cancelled by radiofrequency fields: the involvement of radical pair mechanisms.

PubMed

de Melo, Roger Duarte; Acosta-Avalos, Daniel

2017-02-01

'Candidatus Magnetoglobus multicellularis' is the most studied multicellular magnetotactic prokaryote. It presents a light-dependent photokinesis: green light decreases the translation velocity whereas red light increases it, in comparison to blue and white light. The present article shows that radio-frequency electromagnetic fields cancel the light effect on photokinesis. The frequency to cancel the light effect corresponds to the Zeeman resonance frequency (DC magnetic field of 4 Oe and radio-frequency of 11.5 MHz), indicating the involvement of a radical pair mechanism. An analysis of the orientation angle relative to the magnetic field direction shows that radio-frequency electromagnetic fields disturb the swimming orientation when the microorganisms are illuminated with red light. The analysis also shows that at low magnetic fields (1.6 Oe) the swimming orientation angles are well scattered around the magnetic field direction, showing that magnetotaxis is not efficiently in the swimming orientation to the geomagnetic field. The results do not support cryptochrome as being the responsible chromophore for the radical pair mechanism and perhaps two different chromophores are necessary to explain the radio-frequency effects.

Study of the performance of Micromegas detectors in magnetic field

NASA Astrophysics Data System (ADS)

Dimitrios, Sampsonidis

2018-02-01

Resistive Micromegas (MICRO MEsh GAseous Structure) detectors have been chosen by the ATLAS collaboration at LHC for the high luminosity upgrade, due to their capability to maintain full efficiency and high spatial resolution at high occupancy, for tracking muons in the forward region of the detector. The Inner Muon Station, in the high-rapidity region, the so called New Small Wheel (NSW), will be composed of micromegas detectors that will have to maintain good performance in the presence of magnetic field of up to about 0.3 T. The response of micromegas detectors is affected by the magnetic field, where the deflection of the drift electrons is described by the Lorentz angle, resulting in a bias in the reconstructed track position. Several test-beam campaigns have been performed to test the behaviour of small size resistive micromegas prototypes (10×10 cm2) in magnetic fields up to 1 T, using high momentum muon and hadron beams at CERN. These studies are performed in order to validate the capability of the chambers to provide unbiased tracks in the NSW conditions. Measurements of the Lorentz angle and drift velocity as a function of the magnetic field are presented and both are compared to expectations based on Garfield-Magboltz simulations. Several methods to correct the position bias are applied, based on the chamber configuration or on the knowledge of the local value of the magnetic field. The results of these studies are presented together with an overall discussion of the Micromegas tracking capability in magnetic field.

Introduction to Vector Field Visualization

NASA Technical Reports Server (NTRS)

Kao, David; Shen, Han-Wei

2010-01-01

Vector field visualization techniques are essential to help us understand the complex dynamics of flow fields. These can be found in a wide range of applications such as study of flows around an aircraft, the blood flow in our heart chambers, ocean circulation models, and severe weather predictions. The vector fields from these various applications can be visually depicted using a number of techniques such as particle traces and advecting textures. In this tutorial, we present several fundamental algorithms in flow visualization including particle integration, particle tracking in time-dependent flows, and seeding strategies. For flows near surfaces, a wide variety of synthetic texture-based algorithms have been developed to depict near-body flow features. The most common approach is based on the Line Integral Convolution (LIC) algorithm. There also exist extensions of LIC to support more flexible texture generations for 3D flow data. This tutorial reviews these algorithms. Tensor fields are found in several real-world applications and also require the aid of visualization to help users understand their data sets. Examples where one can find tensor fields include mechanics to see how material respond to external forces, civil engineering and geomechanics of roads and bridges, and the study of neural pathway via diffusion tensor imaging. This tutorial will provide an overview of the different tensor field visualization techniques, discuss basic tensor decompositions, and go into detail on glyph based methods, deformation based methods, and streamline based methods. Practical examples will be used when presenting the methods; and applications from some case studies will be used as part of the motivation.

Role of poloidal flows on the particle confinement time in a simple toroidal device : an experimental study

NASA Astrophysics Data System (ADS)

Kumar, Umesh; Ganesh, R.; Saxena, Y. C.; Thatipamula, Shekar G.; Sathyanarayana, K.; Raju, Daniel

2017-10-01

In magnetized toroidal devices without rotational transform also known as Simple Magnetized Torus (SMT). The device BETA at the IPR is one such SMT with a major radius of 45 cm, minor radius of 15 cm and a maximum toroidal field of 0.1 Tesla. Understanding confinement in such helical configurations is an important problem both for fundamental plasma physics and for Tokamak edge physics. In a recent series of experiments it was demonstrated experimentally that the mean plasma profiles, fluctuation, flow and turbulence depend crucially on the parallel connection length, which was controlled by external vertical field. In the present work, we report our experimental findings, wherein we measure the particle confinement time for hot cathode discharge and ECRH discharge, with variation in parallel connection length. As ECRH plasma don't have mean electric field and hence the poloidal rotation of plasma is absent. However, in hot cathode discharge, there exist strong poloidal flows due to mean electric field. An experimental comparison of these along with theoretical model with variation in connection length will be presented. We also present experimental measurements of variation of plasma confinement time with mass as well as the ratio of vertical field to toroidal magnetic field.

Probing Interfacial Friction and Dissipation in Granular Gold­ Nickel Alloys with a Quartz Crystal Oscillator in an External Magnetic Field

NASA Astrophysics Data System (ADS)

Stevens, K. M.; Krim, J.

2015-03-01

We present here a quartz crystal microbalance study of two-phase gold nickel alloys whose internal granular properties are probed by exposure to a fluctuating external magnetic field. The work is motivated by prior studies demonstrating that granular two-phase materials exhibited lower friction and wear than solid solution alloys with identical compositions. In particular, we report a ``flexing'' effect which appears when an external magnetic field is applied, and is manifested as a decrease in the magnitude of oscillation amplitude that is synchronized with the applied field; the effect is not seen on the complimentary solid solution samples. The effect is consistent with internal interfacial friction between nickel and gold grains, indicating a degree of freedom which may decrease friction even in the absence of an external magnetic field. This is supported through analysis of energy dissipation in the system, using the Butterworth­-Van Dyke equivalent circuit model. Data and interpretation are also presented that rule out alternate explanations such as giant magnetoresistance and/or other resistive phenomenon within the film. Funding provided by NSF DMR0805204. Thanks to L. Pan for sample preparation.

Neuroanthropology: a humanistic science for the study of the culture–brain nexus

PubMed Central

Turner, Robert; Lewis, E. Douglas; Egan, Gary

2010-01-01

In this article, we argue that a combined anthropology/neuroscience field of enquiry can make a significant and distinctive contribution to the study of the relationship between culture and the brain. This field, which can appropriately be termed as neuroanthropology, is conceived of as being complementary to and mutually informative with social and cultural neuroscience. We start by providing an introduction to the culture concept in anthropology. We then present a detailed characterization of neuroanthropology and its methods and how they relate to the anthropological understanding of culture. The field is described as a humanistic science, that is, a field of enquiry founded on the perceived epistemological and methodological interdependence of science and the humanities. We also provide examples that illustrate the proposed methodological model for neuroanthropology. We conclude with a discussion about specific contributions the field can make to the study of the culture–brain nexus. PMID:19654141

Armenian Cultural Astronomy

NASA Astrophysics Data System (ADS)

Farmanyan, S. V.; Mickaelian, A. M.

2015-07-01

Cultural Astronomy is the reflection of sky events in various fields of nations' culture. In foreign literature this field is also called "Astronomy in Culture" or "Astronomy and Culture". Cultural astronomy is the set of interdisciplinary fields studying the astronomical systems of current or ancient societies and cultures. It is manifested in Religion, Mythology, Folklore, Poetry, Art, Linguistics and other fields. In recent years, considerable attention has been paid to this sphere, particularly international organizations were established, conferences are held and journals are published. Armenia is also rich in cultural astronomy. The present paper focuses on Armenian archaeoastronomy and cultural astronomy, including many creations related to astronomical knowledge; calendars, rock art, mythology, etc. On the other hand, this subject is rather poorly developed in Armenia; there are only individual studies on various related issues (especially many studies related to Anania Shirakatsi) but not coordinated actions to manage this important field of investigation.

Cultural Astronomy in Armenia and in the World

NASA Astrophysics Data System (ADS)

Farmanyan, S. V.; Mickaelian, A. M.

2016-12-01

Cultural Astronomy is the reflection of sky events in various fields of nations' culture. In foreign literature, this field is also called "Astronomy in Culture" or "Astronomy and Culture". Cultural astronomy is the set of interdisciplinary fields studying the astronomical systems of current or ancient societies and cultures. It is manifested in Religion, Mythology, Folklore, Poetry, Art, Linguistics and other fields. In recent years, considerable attention has been paid to this sphere, particularly international organizations were established, conferences are held and journals are published. Armenia is also rich in cultural astronomy. The present paper focuses on Armenian archaeoastronomy and cultural astronomy, including many creations related to astronomical knowledge; calendars, rock art, mythology, etc. On the other hand, this subject is rather poorly developed in Armenia; there are only individual studies on various related issues (especially many studies related to Anania Shirakatsi) but not coordinated actions to manage this important field of investigation.

Neuroanthropology: a humanistic science for the study of the culture-brain nexus.

PubMed

Domínguez Duque, Juan F; Turner, Robert; Lewis, E Douglas; Egan, Gary

2010-06-01

In this article, we argue that a combined anthropology/neuroscience field of enquiry can make a significant and distinctive contribution to the study of the relationship between culture and the brain. This field, which can appropriately be termed as neuroanthropology, is conceived of as being complementary to and mutually informative with social and cultural neuroscience. We start by providing an introduction to the culture concept in anthropology. We then present a detailed characterization of neuroanthropology and its methods and how they relate to the anthropological understanding of culture. The field is described as a humanistic science, that is, a field of enquiry founded on the perceived epistemological and methodological interdependence of science and the humanities. We also provide examples that illustrate the proposed methodological model for neuroanthropology. We conclude with a discussion about specific contributions the field can make to the study of the culture-brain nexus.

Aircraft measurements of electrified clouds at Kennedy Space Center. Part 2: Case study: 4 November 1988 (88309)

NASA Technical Reports Server (NTRS)

Jones, J. J.; Winn, W. P.; Hunyady, S. J.; Moore, C. B.; Bullock, J. W.

1990-01-01

During the fall of 1988, a Schweizer airplane equipped to measure electric field and other meteorological parameters flew over Kennedy Space Center (KSC) in a program to study clouds defined in the existing launch restriction criteria. A case study is presented of a single flight over KSC on November 4, 1988. This flight was chosen for two reasons: (1) the clouds were weakly electrified, and no lightning was reported during the flight; and (2) electric field mills in the surface array at KSC indicated field strengths greater than 3 kV/m, yet the aircraft flying directly over them at an altitude of 3.4 km above sea level measured field strengths of less than 1.6 kV/m. A weather summary, sounding description, record of cloud types, and an account of electric field measurements are included.

Zebrafish respond to the geomagnetic field by bimodal and group-dependent orientation.

PubMed

Takebe, Akira; Furutani, Toshiki; Wada, Tatsunori; Koinuma, Masami; Kubo, Yoko; Okano, Keiko; Okano, Toshiyuki

2012-01-01

A variety of animals use Earth's magnetic field as a reference for their orientation behaviour. Although distinctive magnetoreception mechanisms have been postulated for many migrating or homing animals, the molecular mechanisms are still undefined. In this study, we found that zebrafish, a model organism suitable for genetic manipulation, responded to a magnetic field as weak as the geomagnetic field. Without any training, zebrafish were individually released into a circular arena that was placed in an artificial geomagnetic field, and their preferred magnetic directions were recorded. Individuals from five out of the seven zebrafish groups studied, groups mostly comprised of the offspring of predetermined pairs, showed bidirectional orientation with group-specific preferences regardless of close kinships. The preferred directions did not seem to depend on gender, age or surrounding environmental factors, implying that directional preference was genetically defined. The present findings may facilitate future study on the molecular mechanisms underlying magnetoreception.

Initial singularity and pure geometric field theories

NASA Astrophysics Data System (ADS)

Wanas, M. I.; Kamal, Mona M.; Dabash, Tahia F.

2018-01-01

In the present article we use a modified version of the geodesic equation, together with a modified version of the Raychaudhuri equation, to study initial singularities. These modified equations are used to account for the effect of the spin-torsion interaction on the existence of initial singularities in cosmological models. Such models are the results of solutions of the field equations of a class of field theories termed pure geometric. The geometric structure used in this study is an absolute parallelism structure satisfying the cosmological principle. It is shown that the existence of initial singularities is subject to some mathematical (geometric) conditions. The scheme suggested for this study can be easily generalized.

Hanle Effect Diagnostics of the Coronal Magnetic Field: A Test Using Realistic Magnetic Field Configurations

NASA Astrophysics Data System (ADS)

Raouafi, N.-E.; Solanki, S. K.; Wiegelmann, T.

2009-06-01

Our understanding of coronal phenomena, such as coronal plasma thermodynamics, faces a major handicap caused by missing coronal magnetic field measurements. Several lines in the UV wavelength range present suitable sensitivity to determine the coronal magnetic field via the Hanle effect. The latter is a largely unexplored diagnostic of coronal magnetic fields with a very high potential. Here we study the magnitude of the Hanle-effect signal to be expected outside the solar limb due to the Hanle effect in polarized radiation from the H I Lyα and β lines, which are among the brightest lines in the off-limb coronal FUV spectrum. For this purpose we use a magnetic field structure obtained by extrapolating the magnetic field starting from photospheric magnetograms. The diagnostic potential of these lines for determining the coronal magnetic field, as well as their limitations are studied. We show that these lines, in particular H I Lyβ, are useful for such measurements.

Stressing biological samples with pulsed magnetic fields: physical aspects and experimental results

NASA Astrophysics Data System (ADS)

Delle Side, D.; Specchia, V.; D'Attis, S.; Giuffreda, E.; Quarta, G.; Calcagnile, L.; Bozzetti, M. P.; Nassisi, V.

2016-05-01

Magnetic field effects are diffused among living organisms. They are mainly studied with static or extremely low frequency fields, while scarce information is available for pulsed fields. This work is devoted to the study of the interaction between Drosophila melanogaster, both adults and larvae, and pulsed magnetic fields. We exposed the organisms to a peak field of 0.4 T, lasting for about 2 μ s, within an ad hoc designed copper coil. Adult individuals didn't present any deregulation of repetitive sequences in the germ line of Drosophila. Instead, we noticed a marked magnetic field effect in larvae. Polytene chromosomes coming from treated individuals showed the presence of heat shock puffs; the same organisms revealed also an upregulation of the genes encoding for the Hsp70 protein. These observations suggest that the larvae underwent an oxidative stress caused by the modulation of free radicals' yield induced by the magnetic field through a radical pair mechanism.

Dark current, breakdown, and magnetic field effects in a multicell, 805MHz cavity

NASA Astrophysics Data System (ADS)

Norem, J.; Wu, V.; Moretti, A.; Popovic, M.; Qian, Z.; Ducas, L.; Torun, Y.; Solomey, N.

2003-07-01

We present measurements of dark currents and x rays in a six cell 805MHz cavity, taken as part of an rf development program for muon cooling, which requires high power, high stored energy, low frequency cavities operating in a strong magnetic field. We have done the first systematic study of the behavior of high power rf in a strong (2.5 4T) magnetic field. Our measurements extend over a very large dynamic range in current and provide good fits to the Fowler-Nordheim field emission model assuming mechanical structures produce field enhancements at the surface. The locally enhanced field intensities we derive at the tips of these emitters are very large, (˜10 GV/m), and should produce tensile stresses comparable to the tensile strength of the copper cavity walls and should be capable of causing breakdown events. We also compare our data with estimates of tensile stresses from a variety of accelerating structures. Preliminary studies of the internal surface of the cavity and window are presented, which show splashes of copper with many sharp cone shaped protrusions and wires which can explain the experimentally measured field enhancements. We discuss a “cold copper” breakdown mechanism and briefly review alternatives. We also discuss a number of effects due to the 2.5T solenoidal fields on the cavity such as altered field emission due to mechanical deformation of emitters, and dark current ring beams, which are produced from the irises by E×B drifts during the nonrelativistic part of the acceleration process.

Intensity variation study of the radiation field in a mammographic system using thermoluminescent dosimeters TLD-900 (CaSO4:Dy)

NASA Astrophysics Data System (ADS)

Corrêa, E. L.; Silva, J. O.; Vivolo, V.; Potiens, M. P. A.; Daros, K. A. C.; Medeiros, R. B.

2014-02-01

This study presents the results of the intensity variation of the radiation field in a mammographic system using the thermoluminescent dosimeter TLD-900 (CaSO4:Dy). These TLDs were calibrated and characterized in an industrial X-ray system used for instruments calibration, in the energy range used in mammography. They were distributed in a matrix of 19 lines and five columns, covering an area of 18 cm×8 cm in the center of the radiation field on the clinical equipment. The results showed a variation of the intensity probably explained by the non-uniformity of the field due to the heel effect.

GeoWall use in an Introductory Geology laboratory: Impacts in Student Understanding of Field Mapping Concepts

NASA Astrophysics Data System (ADS)

Ross, L. E.; Kelly, M.; Springer, A. E.

2003-12-01

In the Fall semester of 2003, Northern Arizona University will introduce the GeoWall to its introductory geology courses. This presents an opportunity to assess the impact of this new technology on students' understanding of basic topographic concepts and the spatial relationships between geology, topography, and hydrology on a field trip. Introductory Geology fulfills the Lab Science component of the Liberal Studies Program at Northern Arizona University. The class is open to all Northern Arizona University students, and is most commonly taken by non-science majors. In this class students learn to: locate their position using maps, identify common minerals and rocks, recognize the relationship between geology and geomorphology, visualize how rocks exposed at the surface continue into the subsurface, and to draw conclusions about possible geologic hazards in different settings. In this study we will report how a GeoWall 3D visualization technology was used in a field study of a graben south of Flagstaff. The goal of the field exercise is to improve students' ability to synthesize data collected at field stops into a conceptual model of the graben, linking geology, geomorphology and hydrology. We plan to present a quantitative assessment of the GeoWall learning objectives from data collected from a paired test and control group of students. Teaching assistants (TAs) with two or more lab classes have been identified; these TAs will participate in both GeoWall and non-GeoWall lab exercises. The GeoWall use will occur outside of normal lab hours to avoid disrupting the lab schedule during the eighth week of lab. This field preparation exercise includes a 3D visualization of the Lake Mary graben rendered with the ROMA software. The following week, all students attend the graben field trip; immediately following the trip, students will interviewed about their gain in understanding of the geologic features illustrated during the field trip. The results of the post-fieldtrip interviews will also be presented to quantitatively assess how students perceive the use of the GeoWall in this introductory geology setting, and how it affected their understanding.

Effect of magnetic field on noncollinear magnetism in classical bilinear-biquadratic Heisenberg model

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

Pasrija, Kanika, E-mail: kanikapasrija@iisermohali.ac.in; Kumar, Sanjeev, E-mail: sanjeev@iisermohali.ac.in

We present a Monte Carlo simulation study of a bilinear-biquadratic Heisenberg model on a two-dimensional square lattice in the presence of an external magnetic field. The study is motivated by the relevance of this simple model to the non-collinear magnetism and the consequent ferroelectric behavior in the recently discovered high-temperature multiferroic, cupric oxide (CuO). We show that an external magnetic field stabilizes a non-coplanar magnetic phase, which is characterized by a finite ferromagnetic moment along the direction of the applied magnetic field and a spiral spin texture if projected in the plane perpendicular to the magnetic field. Real-space analysis highlightsmore » a coexistence of non-collinear regions with ferromagnetic clusters. The results are also supported by simple variational calculations.« less

Nonlinear whistler wave model for lion roars in the Earth's magnetosheath

NASA Astrophysics Data System (ADS)

Dwivedi, N. K.; Singh, S.

2017-09-01

In the present study, we construct a nonlinear whistler wave model to explain the magnetic field spectra observed for lion roars in the Earth's magnetosheath region. We use two-fluid theory and semi-analytical approach to derive the dynamical equation of whistler wave propagating along the ambient magnetic field. We examine the magnetic field localization of parallel propagating whistler wave in the intermediate beta plasma applicable to the Earth's magnetosheath. In addition, we investigate spectral features of the magnetic field fluctuations and the spectral slope value. The magnetic field spectrum obtained by semi-analytical approach shows a spectral break point and becomes steeper at higher wave numbers. The observations of IMP 6 plasma waves and magnetometer experiment reveal the existence of short period magnetic field fluctuations in the magnetosheath. The observation shows the broadband spectrum with a spectral slope of -4.5 superimposed with a narrow band peak. The broadband fluctuations appear due to the energy cascades attributed by low-frequency magnetohydrodynamic modes, whereas, a narrow band peak is observed due to the short period lion roars bursts. The energy spectrum predicted by the present theoretical model shows a similar broadband spectrum in the wave number domain with a spectral slope of -3.2, however, it does not show any narrow band peak. Further, we present a comparison between theoretical energy spectrum and the observed spectral slope in the frequency domain. The present semi-analytical model provides exposure to the whistler wave turbulence in the Earth's magnetosheath.

The Mediterranean surface wave climate inferred from future scenario simulations

NASA Astrophysics Data System (ADS)

Lionello, P.; Cogo, S.; Galati, M. B.; Sanna, A.

2008-09-01

This study is based on 30-year long simulations of the wind-wave field in the Mediterranean Sea carried out with the WAM model. Wave fields have been computed for the 2071-2100 period of the A2, B2 emission scenarios and for the 1961-1990 period of the present climate (REF). The wave model has been forced by the wind field computed by a regional climate model with 50 km resolution. The mean SWH (Significant Wave Height) field over large fraction of the Mediterranean sea is lower for the A2 scenario than for the present climate during winter, spring and autumn. During summer the A2 mean SWH field is also lower everywhere, except for two areas, those between Greece and Northern Africa and between Spain and Algeria, where it is significantly higher. All these changes are similar, though smaller and less significant, in the B2 scenario, except during winter in the north-western Mediterranean Sea, when the B2 mean SWH field is higher than in the REF simulation. Also extreme SWH values are smaller in future scenarios than in the present climate and such SWH change is larger for the A2 than for the B2 scenario. The only exception is the presence of higher SWH extremes in the central Mediterranean during summer for the A2 scenario. In general, changes of SWH, wind speed and atmospheric circulation are consistent, and results show milder marine storms in future scenarios than in the present climate.

Concept of a staged FEL enabled by fast synchrotron radiation cooling of laser-plasma accelerated beam by solenoidal magnetic fields in plasma bubble

NASA Astrophysics Data System (ADS)

Seryi, Andrei; Lesz, Zsolt; Andreev, Alexander; Konoplev, Ivan

2017-03-01

A novel method for generating GigaGauss solenoidal fields in a laser-plasma bubble, using screw-shaped laser pulses, has been recently presented. Such magnetic fields enable fast synchrotron radiation cooling of the beam emittance of laser-plasma accelerated leptons. This recent finding opens a novel approach for design of laser-plasma FELs or colliders, where the acceleration stages are interleaved with laser-plasma emittance cooling stages. In this concept paper, we present an outline of what a staged plasma-acceleration FEL could look like, and discuss further studies needed to investigate the feasibility of the concept in detail.

Lunar magnetic permeability, magnetic fields, and electrical conductivity temperature

NASA Technical Reports Server (NTRS)

Parkin, C. W.

1978-01-01

In the time period 1969-1972 a total of five magnetometers were deployed on the lunar surface during four Apollo missions. Data from these instruments, along with simultaneous measurements from other experiments on the moon and in lunar orbit, were used to study properties of the lunar interior and the lunar environment. The principal scientific results from analyses of the magnetic field data are discussed. The results are presented in the following main categories: (1) lunar electrical conductivity, temperature, and structure; (2) lunar magnetic permeability, iron abundance, and core size limits; (3) the local remnant magnetic fields, their interaction with the solar wind, and a thermoelectric generator model for their origin. Relevant publications and presented papers are listed.

Thermodynamic properties for applications in chemical industry via classical force fields.

PubMed

Guevara-Carrion, Gabriela; Hasse, Hans; Vrabec, Jadran

2012-01-01

Thermodynamic properties of fluids are of key importance for the chemical industry. Presently, the fluid property models used in process design and optimization are mostly equations of state or G (E) models, which are parameterized using experimental data. Molecular modeling and simulation based on classical force fields is a promising alternative route, which in many cases reasonably complements the well established methods. This chapter gives an introduction to the state-of-the-art in this field regarding molecular models, simulation methods, and tools. Attention is given to the way modeling and simulation on the scale of molecular force fields interact with other scales, which is mainly by parameter inheritance. Parameters for molecular force fields are determined both bottom-up from quantum chemistry and top-down from experimental data. Commonly used functional forms for describing the intra- and intermolecular interactions are presented. Several approaches for ab initio to empirical force field parameterization are discussed. Some transferable force field families, which are frequently used in chemical engineering applications, are described. Furthermore, some examples of force fields that were parameterized for specific molecules are given. Molecular dynamics and Monte Carlo methods for the calculation of transport properties and vapor-liquid equilibria are introduced. Two case studies are presented. First, using liquid ammonia as an example, the capabilities of semi-empirical force fields, parameterized on the basis of quantum chemical information and experimental data, are discussed with respect to thermodynamic properties that are relevant for the chemical industry. Second, the ability of molecular simulation methods to describe accurately vapor-liquid equilibrium properties of binary mixtures containing CO(2) is shown.

Euclidean mirrors: enhanced vacuum decay from reflected instantons

NASA Astrophysics Data System (ADS)

Akal, Ibrahim; Moortgat-Pick, Gudrid

2018-05-01

We study the tunnelling of virtual matter–antimatter pairs from the quantum vacuum in the presence of a spatially uniform, time-dependent electric background composed of a strong, slow field superimposed with a weak, rapid field. After analytic continuation to Euclidean spacetime, we obtain from the instanton equations two critical points. While one of them is the closing point of the instanton path, the other serves as an Euclidean mirror which reflects and squeezes the instanton. It is this reflection and shrinking which is responsible for an enormous enhancement of the vacuum pair production rate. We discuss how important features of two different mechanisms can be analysed and understood via such a rotation in the complex plane. (a) Consistent with previous studies, we first discuss the standard assisted mechanism with a static strong field and certain weak fields with a distinct pole structure in order to show that the reflection takes place exactly at the poles. We also discuss the effect of possible sub-cycle structures. We extend this reflection picture then to weak fields which have no poles present and illustrate the effective reflections with explicit examples. An additional field strength dependence for the rate occurs in such cases. We analytically compute the characteristic threshold for the assisted mechanism given by the critical combined Keldysh parameter. We discuss significant differences between these two types of fields. For various backgrounds, we present the contributing instantons and perform analytical computations for the corresponding rates treating both fields nonperturbatively. (b) In addition, we also study the case with a nonstatic strong field which gives rise to the assisted dynamical mechanism. For different strong field profiles we investigate the impact on the critical combined Keldysh parameter. As an explicit example, we analytically compute the rate by employing the exact reflection points. The validity of the predictions for both mechanisms is confirmed by numerical computations.

Partial slip effect in the flow of MHD micropolar nanofluid flow due to a rotating disk - A numerical approach

NASA Astrophysics Data System (ADS)

Ramzan, Muhammad; Chung, Jae Dong; Ullah, Naeem

The aim of present exploration is to study the flow of micropolar nanofluid due to a rotating disk in the presence of magnetic field and partial slip condition. The governing coupled partial differential equations are reduced to nonlinear ordinary differential equations using appropriate transformations. The differential equations are solved numerically by using Maple dsolve command with option numeric which utilize Runge-Kutta fourth-fifth order Fehlberg technique. A comparison to previous study is also added to validate the present results. Moreover, behavior of different parameters on velocity, microrotation, temperature and concentration of nanofluid are presented via graphs and tables. It is noted that the slip effect and magnetic field decay the velocity and microrotation or spin component.

The Sagittarius Dwarf Galaxy Survey (SDGS): Constraints on the Star Formation History of the Sgr dSph

NASA Astrophysics Data System (ADS)

Bellazzini, M.; Ferraro, F. R.; Buonanno, R.

1999-01-01

We present the first results of a large photometric survey devoted to the study of the star formation history in the Sagittarius dwarf spheroidal galaxy (Sgr dSph). Three large (size: 9 x 35 arcmin2) and widely spaced fields located nearly along the Sgr dSph major axis [(l,b) = (6.5 -16);(6-14);(5-12)] have been observed in the V and I passbands with the ESO-NTT 3.5-m telescope (La Silla - Chile). Well-calibrated photometry has been obtained for ˜90000 stars toward Sgr dSph and for ˜9000 stars in a (9 x 24 arcmin2) control field down to a limiting magnitude of V 22. At present this is the largest photometric (CCD) sample of Sgr dSph stars and the wide spacing between field provides the first opportunity of studying the stellar content of different regions of the galaxy (over a range of ˜2 Kpc across). Age and metallicity estimates are obtained for the detected stellar populations and the very first evidences are presented for (a) spatial differences in the stellar content and (b) the detection of a very metal poor population in the field of the Sgr galaxy.

Stress field forming of sector array transducers for vibro-acoustography.

PubMed

Silva, Glauber T; Chen, Shigao; Frery, Alejandro C; Greenleaf, James F; Fatemi, Mostafa

2005-11-01

This paper presents a study of the stress field forming of sector array transducers for vibro-acoustography applications. The system point-spread function (PSF) is given in terms of the dynamic radiation stress exerted on a point target by a dual ultrasound beam with slightly different frequencies. The radiation stress is calculated by assuming that the resulting ultrasound beam is a plane wave. The stress is proportional to the product of the velocity potential of each incident ultrasound beam. The beamforming and stress field forming of sector array transducers are analyzed through linear acoustics. An expression for the velocity potential produced by sector array transducers is derived. The vibro-acoustography PSF is evaluated numerically. A comparison between the PSF of a sector array and a confocal transducers is presented. The compared characteristics of the PSF are sidelobe levels, transverse, and in-depth spatial resolution. Indeed, one motivation to study sector transducers is the fact the depth-of-field of these transducers should be smaller than that of same size confocal transducers. An experimental setup was used to validate the theoretical PSF of sector array transducers. Results show that the measured PSF is in good agreement with the theoretical predications. Vibro-acoustography images of a breast-phantom by both transducers are presented and discussed.

The study of the dynamics of erythrocytes under the influence of an external electric field

NASA Astrophysics Data System (ADS)

Mamaeva, Sargylana N.; Maksimov, Georgy V.; Antonov, Stepan R.

2017-11-01

A mathematical model is considered for the determination of the surface charge of an erythrocyte with its shape approximated by a surface of revolution of the second order, and the investigation of the dynamics of erythrocytes under the influence of an external electric field. In the first part of this work, the electrical surface charge of the erythrocyte of the patient was calculated with the assumption that the change in the shape and size of the red blood cells leads to stabilization of the electric field, providing a normal electrostatic repulsion. In the second part of the work, the research results of dynamics of changes in the morphology of erythrocytes under the influence of an external electric field depending on the values of their surface charge and resistance of blood plasma is presented. In the course of the work, the dependence of the surface charge of red blood cells from their shape and size is presented. The determination of the relationship between the value of the charge field and the surface of erythrocytes in norm and in pathology is shown. The dependence of the velocity of the erythrocytes on the characteristics of the external electric field, surface charge of the erythrocyte and properties of the medium is obtained. The results of this study can be applied indirectly to diagnose diseases and to develop recommendations for experimental studies of hemodynamics under the influence of various external physical factors.

Imposed magnetic field and hot electron propagation in inertial fusion hohlraums

DOE PAGES

Strozzi, David J.; Perkins, L. J.; Marinak, M. M.; ...

2015-12-02

The effects of an imposed, axial magnetic fieldmore » $$B_{z0}$$ on hydrodynamics and energetic electrons in inertial confinement fusion indirect-drive hohlraums are studied. We present simulations from the radiation-hydrodynamics code HYDRA of a low-adiabat ignition design for the National Ignition Facility, with and without $$B_{z0}=70~\\text{T}$$. The field’s main hydrodynamic effect is to significantly reduce electron thermal conduction perpendicular to the field. This results in hotter and less dense plasma on the equator between the capsule and hohlraum wall. The inner laser beams experience less inverse bremsstrahlung absorption before reaching the wall. The X-ray drive is thus stronger from the equator with the imposed field. We study superthermal, or ‘hot’, electron dynamics with the particle-in-cell code ZUMA, using plasma conditions from HYDRA. During the early-time laser picket, hot electrons based on two-plasmon decay in the laser entrance hole (Regan et al., Phys. Plasmas, vol. 17(2), 2010, 020703) are guided to the capsule by a 70 T field. Twelve times more energy deposits in the deuterium–tritium fuel. For plasma conditions early in peak laser power, we present mono-energetic test-case studies with ZUMA as well as sources based on inner-beam stimulated Raman scattering. Furthermore, the effect of the field on deuterium–tritium deposition depends strongly on the source location, namely whether hot electrons are generated on field lines that connect to the capsule.« less

Open-field exposure facilitates consummatory extinction.

PubMed

Justel, Nadia; Psyrdellis, Mariana; Pautassi, Ricardo M

2016-12-07

During extinction, the organism learns that a conditioned stimulus or a conditioned response is no longer associated with an unconditioned stimulus, and as a consequence, a decrement in the response is presented. The exposure to novel situations (e.g. exploration of a novel open field) has been used widely to modulate (i.e. either enhance or deteriorate) learning and memory. The aim of the present study was to test whether open-field exposure could modulate consummatory extinction. The results indicated that open-field exposure accelerated the extinction response (i.e. experimental animals provided novelty exposure had lower consummatory behavior than control animals) when applied before - but not after - the first extinction trial, or when applied before the second extinction trial. The results suggest that environmental treatments such as novelty exposure provide a valuable, nonpharmacological alternative to potentially modulate extinction processes.

Topographic Distribution of Stimulus-Specific Adaptation across Auditory Cortical Fields in the Anesthetized Rat

PubMed Central

Nieto-Diego, Javier; Malmierca, Manuel S.

2016-01-01

Stimulus-specific adaptation (SSA) in single neurons of the auditory cortex was suggested to be a potential neural correlate of the mismatch negativity (MMN), a widely studied component of the auditory event-related potentials (ERP) that is elicited by changes in the auditory environment. However, several aspects on this SSA/MMN relation remain unresolved. SSA occurs in the primary auditory cortex (A1), but detailed studies on SSA beyond A1 are lacking. To study the topographic organization of SSA, we mapped the whole rat auditory cortex with multiunit activity recordings, using an oddball paradigm. We demonstrate that SSA occurs outside A1 and differs between primary and nonprimary cortical fields. In particular, SSA is much stronger and develops faster in the nonprimary than in the primary fields, paralleling the organization of subcortical SSA. Importantly, strong SSA is present in the nonprimary auditory cortex within the latency range of the MMN in the rat and correlates with an MMN-like difference wave in the simultaneously recorded local field potentials (LFP). We present new and strong evidence linking SSA at the cellular level to the MMN, a central tool in cognitive and clinical neuroscience. PMID:26950883

Multiple Spacecraft Study of the Impact of Turbulence on Reconnection Rates

NASA Technical Reports Server (NTRS)

Wendel, Deirdre; Goldstein, Melvyn; Figueroa-Vinas, Adolfo; Adrian, Mark; Sahraoui, Fouad

2011-01-01

Magnetic turbulence and secondary island formation have reemerged as possible explanations for fast reconnection. Recent three-dimensional simulations reveal the formation of secondary islands that serve to shorten the current sheet and increase the accelerating electric field, while both simulations and observations witness electron holes whose collapse energizes electrons. However, few data studies have explicitly investigated the effect of turbulence and islands on the reconnection rate. We present a more comprehensive analysis of the effect of turbulence and islands on reconnection rates observed in space. Our approach takes advantage of multiple spacecraft to find the location of the spacecraft relative to the inflow and the outflow, to estimate the reconnection electric field, to indicate the presence and size of islands, and to determine wave vectors indicating turbulence. A superposed epoch analysis provides independent estimates of spatial scales and a reconnection electric field. We apply k-filtering and a new method adopted from seismological analyses to identify the wavevectors. From several case studies of reconnection events, we obtain preliminary estimates of the spectral scaling law, identify wave modes, and present a method for finding the reconnection electric field associated with the wave modes.

Reversed Field Pinch helical self-organization studies with the volume preserving field line tracing code NEMATO

NASA Astrophysics Data System (ADS)

Bonfiglio, D.; Veranda, M.; Cappello, S.; Chacon, L.; Escande, D. F.; Piovesan, P.

2009-11-01

The existence of a Reversed Field Pinch (RFP) dynamo as a (laminar) helical self-organization was anticipated by MHD numerical studies [1]. High current operation in RFX-mod experiment shows such a helical self-organization: strong internal electron transport barriers (ITB) appear and magnetic chaos healing is diagnosed when Single Helical Axis (SHAx) regimes are achieved [2]. We present results of the field line tracing code NEMATO [3] applied to study the magnetic topology resulting from 3D MHD simulations, with the aim of clarifying the conditions for chaos healing in SHAx states. First tests confirm the basic picture: the magnetic chaos due to island overlap is significantly reduced after the expulsion of the dominant mode separatrix. The possible synergy with the presence of magnetic and/or flow shear at the SHAx ITB will also be discussed [4].[4pt] [1] S. Cappello, Plasma Phys. Control. Fusion (2004) & references therein [0pt] [2] R. Lorenzini et al., Nature Phys. (2009) [0pt] [3] J. M. Finn and L. Chacon, Phys. Plasmas (2005) [0pt] [4] M.E. Puiatti et al invited presentation EPS 2009 conference, submitted to Plasma Phys. Control. Fusion

Statistical Comparisons of Meso- and Small-Scale Field-Aligned Currents with Auroral Electron Acceleration Mechanisms from FAST Observations

NASA Astrophysics Data System (ADS)

Dombeck, J. P.; Cattell, C. A.; Prasad, N.; Sakher, A.; Hanson, E.; McFadden, J. P.; Strangeway, R. J.

2016-12-01

Field-aligned currents (FACs) provide a fundamental driver and means of Magnetosphere-Ionosphere (M-I) coupling. These currents need to be supported by local physics along the entire field line generally with quasi-static potential structures, but also supporting the time-evolution of the structures and currents, producing Alfvén waves and Alfvénic electron acceleration. In regions of upward current, precipitating auroral electrons are accelerated earthward. These processes can result in ion outflow, changes in ionospheric conductivity, and affect the particle distributions on the field line, affecting the M-I coupling processes supporting the individual FACs and potentially the entire FAC system. The FAST mission was well suited to study both the FACs and the electron auroral acceleration processes. We present the results of the comparisons between meso- and small-scale FACs determined from FAST using the method of Peria, et al., 2000, and our FAST auroral acceleration mechanism study when such identification is possible for the entire ˜13 year FAST mission. We also present the latest results of the electron energy (and number) flux ionospheric input based on acceleration mechanism (and FAC characteristics) from our FAST auroral acceleration mechanism study.

The Electron Diffusion Region: Forces and Currents

NASA Technical Reports Server (NTRS)

Hesse, Michael

2008-01-01

The dissipation mechanism of magnetic reconnection remains a subject of intense scientific interest. On one hand, one set of recent studies have shown that particle inertia-based processes, which include thermal and bulk inertial effects, provide the reconnection electric field in the diffusion region. On the other hand, a second set of studies emphasizes the role of wave-particle interactions in providing anomalous resistivity in the diffusion region. In this presentation, we present analytical theory results, as well as PIC simulations of guide-field magnetic reconnection. We will show that the thermal electron inertia-based dissipation mechanism, expressed through nongyrotropic electron pressure tensors, remains viable in three dimensions. We will demonstrate the thermal inertia effect through studies of electron distribution functions. Furthermore, we will show that the reconnection electric field provides a transient acceleration on particles traversing the inner reconnection region. This inertia1 effect can be described as a diffusion-like term of the current density, which matches key features of electron distribution functions.

The Electron Diffusion Region: Forces and Currents

NASA Technical Reports Server (NTRS)

Hesse, Michael

2009-01-01

The dissipation mechanism of magnetic reconnection remains a subject of intense scientific interest. On one hand, one set of recent studies have shown that particle inertia-based processes, which include thermal and bulk inertial effects, provide the reconnection electric field in the diffusion region. On the other hand, a second set of studies emphasizes the role of wave-particle interactions in providing anomalous resistivity in the diffusion region. In this presentation, we present analytical theory results, as well as PIC simulations of guide-field magnetic reconnection. We will show that the thermal electron inertia-based dissipation mechanism, expressed through nongyrotropic electron pressure tensors, remains viable in three dimensions. We will demonstrate the thermal inertia effect through studies of electron distribution functions. Furthermore, we will show that the reconnection electric field provides a transient acceleration on particles traversing the inner reconnection region. This inertial effect can be described as a diffusion-like term of the current density, which matches key features of electron distribution functions.

Effect of electron reflection on magnetized plasma sheath in an oblique magnetic field

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

Wang, Ting-Ting; Ma, J. X., E-mail: jxma@ustc.edu.cn; Wei, Zi-An

Magnetized plasma sheaths in an oblique magnetic field were extensively investigated by conventionally assuming Boltzmann relation for electron density. This article presents the study of the magnetized sheath without using the Boltzmann relation but by considering the electron reflection along the magnetic field lines caused by the negative sheath potential. A generalized Bohm criterion is analytically derived, and sheath profiles are numerically obtained, which are compared with the results of the conventional model. The results show that the ion Mach number at the sheath edge normal to the wall has a strong dependence on the wall potential, which differs significantlymore » from the conventional model in which the Mach number is independent of the wall potential. The floating wall potential is lower in the present model than that in the conventional model. Furthermore, the sheath profiles are appreciably narrower in the present model when the wall bias is low, but approach the result of the conventional model when the wall bias is high. The sheath thickness decreases with the increase of ion-to-electron temperature ratio and magnetic field strength but has a complex relationship with the angle of the magnetic field.« less

Five years later: the current status of the use of proteomics and transcriptomics in EMF research.

PubMed

Leszczynski, Dariusz; de Pomerai, David; Koczan, Dirk; Stoll, Dieter; Franke, Helmut; Albar, Juan Pablo

2012-08-01

The World Health Organization's and Radiation and Nuclear Safety Authority's "Workshop on Application of Proteomics and Transcriptomics in Electromagnetic Fields Research" was held in Helsinki in the October/November 2005. As a consequence of this meeting, Proteomics journal published in 2006 a special issue "Application of Proteomics and Transcriptomics in EMF Research" (Vol. 6 No. 17; Guest Editor: D. Leszczynski). This Proteomics issue presented the status of research, of the effects of electromagnetic fields (EMF) using proteomics and transcriptomics methods, present in 2005. The current overview/opinion article presents the status of research in this area by reviewing all studies that were published by the end of 2010. The review work was a part of the European Cooperation in the Field of Scientific and Technical Research (COST) Action BM0704 that created a structure in which researchers in the field of EMF and health shared knowledge and information. The review was prepared by the members of the COST Action BM0704 task group on the high-throughput screening techniques and electromagnetic fields (TG-HTST-EMF). © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a novel electric field-assisted modified hydrodynamic cavitation system for disintegration of waste activated sludge.

PubMed

Jung, Kyung-Won; Hwang, Min-Jin; Yun, Yeo-Myeong; Cha, Min-Jung; Ahn, Kyu-Hong

2014-09-01

In this current study, we present a modified hydrodynamic cavitation device that combines an electric field to substitute for the chemical addition. A modified HC system is basically an orifice plate and crisscross pipe assembly, in which the crisscross pipe imparts some turbulence, which creates collision events. This study shows that for maximizing disintegration, combining HC system, which called electric field-assisted modified orifice plate hydrodynamic cavitation (EFM-HC) in this study, with an electric field is important. Various HC systems were compared in terms of disintegration of WAS, and, among them, the EFM-HC system exhibited the best performance with the highest disintegration efficiency of 47.0±2.0% as well as the destruction of WAS morphological characteristics. The experimental results clearly show that a conventional HC system was successfully modified. In addition, electric field has a great potential for efficient disintegration of WAS for as a additional option in a combination treatment. This study suggests continued research in this field may lead to an appropriate design for commercial use. Copyright © 2014 Elsevier B.V. All rights reserved.

Relative Cost and Training Effectiveness of the 6883 Three-Dimensional Simulator and Actual Equipment.

DTIC Science & Technology

1980-09-01

evaluated. The objectis e of this study was to isolate classroom and field performance differences as a function of the training equipnment used and to...THIS PAtICmmUn bat. Saelrwo Item 20 (Continued): ausperviser followup questionnaires were administered in the field to provide additional feedback about...competent maintenance technicians to the field . As a train- ing device, actual equipment does not readily permit the controlled presentation of

Relative secular variations of the geomagnetic field along the Zgorzelec-Wiżajny profile, Poland

NASA Astrophysics Data System (ADS)

Wojas, Anna; Grabowska, Teresa; Mikołajczak, Mateusz

2018-03-01

The paper presents results of the study on relative secular variations of total magnetic intensity (TMI) of the geomagnetic field along the 700 km long profile crossing the area of Poland. Surveys were carried out at annual intervals between 1966 and 2016 (50 measurement series), in 31 survey sites (secular points) separated by about 22 km. The studied profile of the SW-NE direction, called Zgorzelec-Wiżajny (Z-W), crosses large parts of the main tectonic units of Europe, namely the Palaeozoic Platform of Central and Western Europe (PLZ) and the East European Craton (EEC), connected by the Teisseyre-Tornquist Zone (TTZ). Using the original methodology of analysis of measured data, reduced to the values of geomagnetic field recorded at the Central Geophysical Observatory in Belsk, the relative secular variations of TMI with the magnetic anomalies (ΔT) and the terrestrial heat flow density (Q) were graphically presented.

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

Li, Mingda; Cui, Wenping; Dresselhaus, Mildred S.

Crystal dislocations govern the plastic mechanical properties of materials but also affect the electrical and optical properties. However, a fundamental and quantitative quantum field theory of a dislocation has remained undiscovered for decades. Here in this article we present an exactly-solvable one-dimensional quantum field theory of a dislocation, for both edge and screw dislocations in an isotropic medium, by introducing a new quasiparticle which we have called the ‘dislon’. The electron-dislocation relaxation time can then be studied directly from the electron self-energy calculation, which is reducible to classical results. In addition, we predict that the electron energy will experience anmore » oscillation pattern near a dislocation. Compared with the electron density’s Friedel oscillation, such an oscillation is intrinsically different since it exists even with only single electron is present. With our approach, the effect of dislocations on materials’ non-mechanical properties can be studied at a full quantum field theoretical level.« less

A Catalog of Averaged Magnetic Curves

NASA Astrophysics Data System (ADS)

Bychkov, V. D.; Bychkova, L. V.; Madej, J.

2017-06-01

The second version of the catalog contains information about 275 stars of different types. Since the first catalog was created, the situation fundamentally changed primarily due to a significant increase of accuracy of magnetic field (MF) measurements. Up to now, global magnetic fields were discovered and measured in stars of many types and their behavior was partially studied. Magnetic behavior of Ap/Bp stars was studied most thoroughly. The catalog contains data on 182 such objects. The main goals for the construction of the catalog are: 1) to review and summarize our knowledge about magnetic behavior of stars of different types; 2) the whole data are uniformly presented and processed which will allow one to perform statistical analysis of the variability of (longitudinal) magnetic fields of stars; 3) the data are presented in the most convenient way for testing different theoretical models; 4) the catalog will be useful for development of observational programs.

Human-Robot Teaming for Hydrologic Data Gathering at Multiple Scales

NASA Astrophysics Data System (ADS)

Peschel, J.; Young, S. N.

2017-12-01

The use of personal robot-assistive technology by researchers and practitioners for hydrologic data gathering has grown in recent years as barriers to platform capability, cost, and human-robot interaction have been overcome. One consequence to this growth is a broad availability of unmanned platforms that might or might not be suitable for a specific hydrologic investigation. Through multiple field studies, a set of recommendations has been developed to help guide novice through experienced users in choosing the appropriate unmanned platforms for a given application. This talk will present a series of hydrologic data sets gathered using a human-robot teaming approach that has leveraged unmanned aerial, ground, and surface vehicles over multiple scales. The field case studies discussed will be connected to the best practices, also provided in the presentation. This talk will be of interest to geoscience researchers and practitioners, in general, as well as those working in fields related to emerging technologies.

Aircraft measurements of electrified clouds at Kennedy Space Center, part 3

NASA Technical Reports Server (NTRS)

Jones, J. J.; Winn, W. P.; Hunyady, S. J.; Moore, C. B.; Bullock, J. W.; Fleischhacker, P.

1990-01-01

Flights made by the Special Purpose Test Vehicle for Atmospheric Research (SPTVAR) airplane during a second deployment to Florida during the summer of 1989 are discussed. The findings based on the data gathered are presented. The progress made during the second year of the project is discussed. The summer 1989 study was carried out with the support and guidance of Col. John Madura, Commander of Detachment 11, 2nd Weather Squadron, USAF, at Patrick Air Force Base (PAFB) and Cape Canaveral Air Force Station. The project goals were to develop and demonstrate techniques for measuring the electric field aloft and locating regions of charge during flight within and near clouds; to characterize the electric conditions that are presently identified as a threat to space launch vehicles; and to study the correlation between the electric field aloft and that at Kennedy Space Center's ground-based electric field mill array for a variety of electrified clouds.

A study of geomagnetic storms

NASA Technical Reports Server (NTRS)

Patel, V. L.

1975-01-01

Twenty-one geomagnetic storm events during 1966 and 1970 were studied by using simultaneous interplanetary magnetic field and plasma parameters. Explorer 33 and 35 field and plasma data were analyzed on large-scale (hourly) and small-scale (3 min.) during the time interval coincident with initial phase of the geomagnetic storms. The solar-ecliptic Bz component turns southward at the end of the initial phase, thus triggering the main phase decrease in Dst geomagnetic field. When the Bz is already negative, its value becomes further negative. The By component also shows large fluctuations along with Bz. When there are no clear changes in the Bz component, the By shows abrupt changes at the main phase onet. On the small-scale behavior of the magnetic field and electric field (E=-VxB) studied in details for the three events, it is found that the field fluctuations in By, Bz and Ey and Ez are present in the initial phase. These fluctuations become larger just before the main phase of the storm begins. In the largescale behavior field remains quiet because the small scale variations are averaged out.

Presenters at NASP 2013-2016: Where Are the Practitioners?

ERIC Educational Resources Information Center

Aspiranti, Kathleen B.; Jackson, Carrie

2018-01-01

Although one of the main functions of school psychology research is to inform practice, there remains a large research-to-practice gap. Both practitioners and scholars are crucial in ensuring that research within the field is comprehensive and well represented. In the current study, presenter, contributor, and presenter affiliation demographics…

Extended effective field theory of inflation

NASA Astrophysics Data System (ADS)

Ashoorioon, Amjad; Casadio, Roberto; Cicoli, Michele; Geshnizjani, Ghazal; Kim, Hyung J.

2018-02-01

We present a general framework where the effective field theory of single field inflation is extended by the inclusion of operators with mass dimension 3 and 4 in the unitary gauge. These higher dimensional operators introduce quartic and sextic corrections to the dispersion relation. We study the regime of validity of this extended effective field theory of inflation and the effect of these higher dimensional operators on CMB observables associated with scalar perturbations, such as the speed of sound, the amplitude of the power spectrum and the tensor-to-scalar ratio. Tensor perturbations remain instead, unaltered.

Field trials to evaluate the effects of transgenic cry1le maize on the community characteristics of arthropod natural enemies

USDA-ARS?s Scientific Manuscript database

Possible non-target effects of transgenic cry1Ie gene maize exerts on natural enemy community biodiversity in the field is unresolved. In the present study, a 2-yr study of transgenic cry1Ie gene maize (Event IE09S034, Bt maize) and its near isoline (Zong 31, non-Bt maize) on natural enemy community...

The Level of Possession of the Students at the Hashemite University of Professional and Family Counseling Skills in Light of Achievement and Gender Variables

ERIC Educational Resources Information Center

ALharbi, Bassam H. M.; Mhaidat, Fatin

2017-01-01

The present study aimed to identify the level of owning a field training students majoring in psychological counseling at the Hashemite University of professional and family counseling skills in light of achievement and gender variables. The subjects of the study comprised of (100) subjects of field training students in the second semester of the…

Alternative ways of using field-based estimates to calibrate ecosystem models and their implications for ecosystem carbon cycle studies

Treesearch

Y. He; Q. Zhuang; A.D. McGuire; Y. Liu; M. Chen

2013-01-01

Model-data fusion is a process in which field observations are used to constrain model parameters. How observations are used to constrain parameters has a direct impact on the carbon cycle dynamics simulated by ecosystem models. In this study, we present an evaluation of several options for the use of observations inmodeling regional carbon dynamics and explore the...

'White matter connectivity and Internet gaming disorder' and broader considerations in the field.

PubMed

Tam, Philip G E

2017-01-01

This invited commentary on the paper 'White Matter Connectivity and Internet gaming disorder' by Jeong et al. (unpublished) looks at the implications and importance of the MRI findings in the present study-one of the largest to date-and also considers the broader developments of neuroimaging within the complex, emerging field of 'Internet psychology' and problematic Internet usage. © 2015 Society for the Study of Addiction.

A methodology based on insecticide impregnated filter paper for monitoring resistance to deltamethrin in Triatoma infestans field populations.

PubMed

Remón, C; Lobbia, P; Zerba, E; Mougabure-Cueto, G

2017-12-01

The domiciliary presence of Triatoma infestans (Klug) (Hemiptera: Reduviidae) after control interventions was reported in recent years. Toxicological studies showed high levels of resistance to pyrethroids suggesting resistance as one of the main causes of deficient control. The aim of the present study was to develop a protocol to test resistance to deltamethrin in T. infestans collected from the field by discriminate concentration. To evaluate field insects, the effect of age (early vs. later) and nutritional state (starved vs. fed) on the deltamethrin susceptibility of each developmental stage was studied. Topical and insecticide impregnated paper bioassays were used. Using the impregnated paper, the susceptibility to deltamethrin was not affected by the age of the stadium and the nutritional states, and varied with the post-exposure time and with the different developmental stages. A discriminant concentration of deltamethrin (0.36% w/v) impregnated in filter paper was established for all developmental stages. Finally, the methodology and the discriminant concentration were evaluated in the laboratory showing high sensitivity in the discrimination of resistance. The present study developed a methodology of exposure to insecticide impregnated papers and proposes a protocol to test T. infestans in field populations with the aim to detect early evolution of resistance to deltamethrin. © 2017 The Royal Entomological Society.

The neuronal substrate of risky choice: an insight into the contributions of neuroimaging to the understanding of theories on decision making under risk.

PubMed

Vorhold, Verena

2008-04-01

This chapter provides an overview of studies in the field of neuroscience that investigate some of the processes and concepts of risk perception, risky choice, and decision making under risk. First, early studies in the field of neuroscience addressing the diminished decision-making abilities in lesion patients are presented. A classical task in this research field is described along with its neural implications. After this, the underlying model, its hypotheses, and neuronal implications are discussed. Different aspects within risky decision making, such as the influence of memory, inhibition, motivation, and personality, on risky choice and the respective underlying neuronal substrate are described. After this, studies of risky decision making in healthy subjects are reviewed. A selection of studies shows that theories focusing on cognitive aspects only have to be enriched in order to allow for additional aspects within risky decision making (e.g., emotion). Next, the classical economic approaches and the development of theories incorporating further aspects within economical decision making and the underlying neuronal substrate will be presented. Finally, research in the field of neuroeconomics, focusing on the role of social decision making and evaluative judgment within risky decision making, is reviewed.

Numerical Study of g-Jitter Induced Double-Diffusive Convection

NASA Technical Reports Server (NTRS)

Shu, Y.; Li, B. Q.; deGroh, Henry C.

2001-01-01

A finite element study is presented of double-diffusive convection driven by g-jitter in a microgravity environment. Mathematical formulations are presented and extensive simulations are carried out for g-jitter induced fluid flow, temperature distribution, and solutal transport in an alloy system under consideration for space flights. Computations include the use of idealized single-frequency and multi-frequency g-jitter as well as the real g-jitter data taken during an actual Space Shuttle fight. Little correlation is seen between these velocity components for the g-jitter components studied. The temperature field is basically undisturbed by convection because of a small Pr number for the fluid. The disturbance of the concentration field, however, is pronounced, and the local variation of the concentration follows the velocity oscillation in time. It is found that although the concentration field varies in both position and time, the local concentration gradient remains approximately constant in time. Numerical study further indicates that with an increase in g-jitter force (or amplitude), the nonlinear convective effects become much more obvious, which in turn drastically change the concentration fields. The simulated results computed using the g-jitter data taken during space flights show that both the velocity and concentration become random, following approximately the same pattern as the g-jitter perturbations.

A preliminary characterization of applied-field MPD thruster plumes

NASA Technical Reports Server (NTRS)

Myers, Roger M.; Wehrle, David; Vernyi, Mark; Biaglow, James; Reese, Shawn

1991-01-01

Electric probes, quantitative imaging, and emission spectroscopy were used to study the plume characteristics of applied field magnetohydrodynamic thrusters. The measurements showed that the applied magnetic field plays the dominant role in establishing the plume structure, followed in importance by the cathode geometry and propellant. The anode radius had no measurable impact on the plume characteristics. For all cases studied the plume was highly ionized, though spectral lines of neutral species were always present. Centerline electron densities and temperatures ranged from 2 times 10 (exp 18) to 8 times 10 (exp 18) m(exp -3) and from 7500 to 20,000 K, respectively. The plume was strongly confined by the magnetic field, with radial density gradients increasing monotonically with applied field strength. Plasma potential measurements show a strong effect of the magnetic field on the electrical conductivity and indicate the presence of radial current conduction in the plume.

Flare onset at sites of maximum magnetic shear

NASA Technical Reports Server (NTRS)

Hagyard, M. J.; Smith, J. B., Jr.

1988-01-01

Observations of the transverse component of the Sun's photospheric magnetic field obtained with the MSFC vector magnetograph show where the fields are nonpotential. The correlation was studied between locations of nonpotential fields and sites of flare onset for four different active regions. The details of the active region AR 4711 are outlined. Similar results are presented for three other regions: AR 2372 (April 1980), AR 2776 (November 1980), and AR 4474 (April 1984). For all four regions it is shown that flares initiate at sites on the magnetic neutral line where the local field deviates the most from the potential field. The results of this study suggest that flares are likely to erupt where the shear is equal to or greater than 85 degrees, the field is equal to or greater than 10000 G, and there is strong shear (equal to or greater then 80 degress) extending over a length equal to or greater than 8000 km.

Electric fields in the plasma sheet and plasma sheet boundary layer

NASA Technical Reports Server (NTRS)

Pedersen, A.; Knott, K.; Cattell, C. A.; Mozer, F. S.; Falthammar, C.-G.; Lindqvist, P.-A.; Manka, R. H.

1985-01-01

Results obtained by Forbes et al. (1981) on the basis of time delay measurements between ISEE 1 and ISEE 2 imply that the plasma flow and the boundary contracting velocity were nearly the same, whereas the expanding boundary velocity was not accompanied by any significant plasma sheet plasma motion. In the present study, this observation is discussed in conjunction with electric field data. The study is based on electric field data from the spherical double probe experiment on ISEE 1. Electric field data from GEOS 2 are used to some extent to monitor the electric fields near the geostationary orbit during the considered eve nts. Electric field data during CDAW 6 events are discussed, taking into account positions of ISEE 1/ISEE 2 and GEOS 2; March 22, 0600-1300 UT; and March 22, UT; and March 31, 1400-2400 UT.

Symmetry breaking and chaos in droplet electrohydrodynamics

NASA Astrophysics Data System (ADS)

Salipante, Paul; Vlahovska, Petia

2010-11-01

A classic result due to G.I.Taylor is that a drop placed in a uniform electric field adopts a prolate or oblate spheroidal shape, the flow and shape being axisymmetrically aligned with the applied field. However, recent studies have revealed an instability and transition to a nonaxisymmetric rotational flow in strong fields, similar to the rotation of solid dielectric particles observed by Quincke in the 19th century. We present an experimental and theoretical study of this phenomenon in DC uniform fields, focusing on nonlinear behavior arising from electromechanial coupling at the fluid-fluid interface. Charge convection by the both rotational and straining flows is included in the our model to explain the dependence of critical electric field on viscosity ratio. Hysteresis in the transition is observed for large low-viscosity drops. At stronger fields, chaotic drop tumbling and sustained shape oscillations are observed.

Dielectrophoresis of Cells

PubMed Central

Pohl, Herbert A.; Crane, Joe S.

1971-01-01

Dielectrophoresis, the motion produced by the action of nonuniform electric field upon a neutral object, is shown to be a simple and useful technique for the study of cellular organisms. In the present study of yeast (Saccharomyces cerevisiae) using a simple pin-pin electrode system of platinum and high-frequency alternating fields, one observes that the collectability of cells at the electrode tip, i.e. at the region of highest field strength, depends upon physical parameters such as field strength, field uniformity, frequency, cell concentration, suspension conductivity, and time of collection. The yield of cells collected is also observed to depend upon biological factors such as colony age, thermal treatment of the cells, and chemical poisons, but not upon irradiation with ultraviolet light. Several interesting side effect phenomena coincident with nonuniform electric field conditions were observed, including stirring (related to “jet” effects at localized electrode sites), discontinuous repulsions, and cellular rotation which was found to be frequency dependent. ImagesFIGURE 2 PMID:5132497

Energy Dissipation and Dynamics in Large Guide Field Turbulence Driven Reconnection at the Magnetopause

NASA Astrophysics Data System (ADS)

TenBarge, J. M.; Shay, M. A.; Sharma, P.; Juno, J.; Haggerty, C. C.; Drake, J. F.; Bhattacharjee, A.; Hakim, A.

2017-12-01

Turbulence and magnetic reconnection are the primary mechanisms responsible for the conversion of stored magnetic energy into particle energy in many space and astrophysical plasmas. The magnetospheric multiscale mission (MMS) has given us unprecedented access to high cadence particle and field data of turbulence and magnetic reconnection at earth's magnetopause. The observations include large guide field reconnection events generated within the turbulent magnetopause. Motivated by these observations, we present a study of large guide reconnection using the fully kinetic Eulerian Vlasov-Maxwell component of the Gkeyll simulation framework, and we also employ and compare with gyrokinetics to explore the asymptotically large guide field limit. In addition to studying the configuration space dynamics, we leverage the recently developed field-particle correlations to diagnose the dominant sources of dissipation and compare the results of the field-particle correlation to other energy dissipation measures.

Molecular modeling studies of structural properties of polyvinyl alcohol: a comparative study using INTERFACE force field.

PubMed

Radosinski, Lukasz; Labus, Karolina

2017-10-05

Polyvinyl alcohol (PVA) is a material with a variety of applications in separation, biotechnology, and biomedicine. Using combined Monte Carlo and molecular dynamics techniques, we present an extensive comparative study of second- and third-generation force fields Universal, COMPASS, COMPASS II, PCFF, and the newly developed INTERFACE, as applied to this system. In particular, we show that an INTERFACE force field provides a possibility of composing a reliable atomistic model to reproduce density change of PVA matrix in a narrow temperature range (298-348 K) and calculate a thermal expansion coefficient with reasonable accuracy. Thus, the INTERFACE force field may be used to predict mechanical properties of the PVA system, being a scaffold for hydrogels, with much greater accuracy than latter approaches. Graphical abstract Molecular Dynamics and Monte Carlo studies indicate that it is possible to predict properties of the PVA in narrow temperature range by using the INTERFACE force field.

Progress in NEXT Ion Optics Modeling

NASA Technical Reports Server (NTRS)

Emhoff, Jerold W.; Boyd, Iain D.

2004-01-01

Results are presented from an ion optics simulation code applied to the NEXT ion thruster geometry. The error in the potential field solver of the code is characterized, and methods and requirements for reducing this error are given. Results from a study on electron backstreaming using the improved field solver are given and shown to compare much better to experimental results than previous studies. Results are also presented on a study of the beamlet behavior in the outer radial apertures of the NEXT thruster. The low beamlet currents in this region allow over-focusing of the beam, causing direct impingement of ions on the accelerator grid aperture wall. Different possibilities for reducing this direct impingement are analyzed, with the conclusion that, of the methods studied, decreasing the screen grid aperture diameter eliminates direct impingement most effectively.

Intercultural Blended Design Considerations: A Case Study of a Nordic-Baltic Course in Autism Intervention

ERIC Educational Resources Information Center

Kack, Annika; Roll-Pettersson, Lise; Alai-Rosales, Shahla S.; Hoium, Kari; Mannikko-Barbutiu, Sirkku; Fors, Uno G. H.

2014-01-01

Specialized educational programs previously unavailable to many students are now accessible to students spread throughout the world. In particular, this globalization presents new opportunities and challenges for universities educating professionals in the field of autism treatment. The aim of the present case study is to analyse the experiences…

[Typing and Shorthand in the Small High School.

ERIC Educational Resources Information Center

Fedel, Joan; Starbuck, Ethel

Two studies conducted in the field of business education are presented in this report by the Colorado State Department of Education. In one study, individualized instruction procedures and individual work packets were developed for students in both first- and second-year typing. Descriptive statistics presented for the 2 groups over a 3-year…

Improving Deliverability in Gas Storage Fields by Identifying the Timing and Sources of Damage Using Smart Well Technology

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

J.H. Frantz Jr; K.G. Brown; W.K. Sawyer

2006-03-01

This report summarizes the work performed under contract DE-FC26-03NT41743. The primary objective of this study was to develop tools that would allow Underground Gas Storage (UGS) operators to use wellhead electronic flow measurement (EFM) data to quickly and efficiently identify trends in well damage over time, thus aiding in the identification of potential causes of the damage. Secondary objectives of this work included: (1) To assist UGS operators in the evaluation of hardware and software requirements for implementing an EFM system similar to the one described in this report, and (2) To provide a cost-benefit analysis framework UGS operators canmore » use to evaluate economic benefits of installing wellhead EFM systems in their particular fields. Assessment of EFM data available for use, and selection of the specific study field are reviewed. The various EFM data processing tasks, including data collection, organization, extraction, processing, and interpretation are discussed. The process of damage assessment via pressure transient analysis of EFM data is outlined and demonstrated, including such tasks as quality control, semi-log analysis, and log-log analysis of pressure transient test data extracted from routinely collected EFM data. Output from pressure transient test analyses for 21 wells is presented, and the interpretation of these analyses to determine the timing of damage development is demonstrated using output from specific study wells. Development of processing and interpretation modules to handle EFM data interpretation in horizontal wells is also a presented and discussed. A spreadsheet application developed to aid underground gas storage operators in the selection of EFM equipment is presented, discussed, and used to determine the cost benefit of installing EFM equipment in a gas storage field. Recommendations for future work related to EFM in gas storage fields are presented and discussed.« less

A simple calculation method for determination of equivalent square field.

PubMed

Shafiei, Seyed Ali; Hasanzadeh, Hadi; Shafiei, Seyed Ahmad

2012-04-01

Determination of the equivalent square fields for rectangular and shielded fields is of great importance in radiotherapy centers and treatment planning software. This is accomplished using standard tables and empirical formulas. The goal of this paper is to present a formula based on analysis of scatter reduction due to inverse square law to obtain equivalent field. Tables are published by different agencies such as ICRU (International Commission on Radiation Units and measurements), which are based on experimental data; but there exist mathematical formulas that yield the equivalent square field of an irregular rectangular field which are used extensively in computation techniques for dose determination. These processes lead to some complicated and time-consuming formulas for which the current study was designed. In this work, considering the portion of scattered radiation in absorbed dose at a point of measurement, a numerical formula was obtained based on which a simple formula was developed to calculate equivalent square field. Using polar coordinate and inverse square law will lead to a simple formula for calculation of equivalent field. The presented method is an analytical approach based on which one can estimate the equivalent square field of a rectangular field and may be used for a shielded field or an off-axis point. Besides, one can calculate equivalent field of rectangular field with the concept of decreased scatter radiation with inverse square law with a good approximation. This method may be useful in computing Percentage Depth Dose and Tissue-Phantom Ratio which are extensively used in treatment planning.

The construction of ``realistic'' four-dimensional strings through orbifolds

NASA Astrophysics Data System (ADS)

Font, A.; Ibáñez, L. E.; Quevedo, F.; Sierra, A.

1990-02-01

We discuss the construction of "realistic" lower rank 4-dimensional strings, through symmetric orbifolds with background fields. We present Z 3 three-generation SU(3) × SU(2) × U(1) models as well as models incorporating a left-right SU(2) L × SU(2) R × U(1) B-L symmetry in which proton stability is automatically guaranteed. Conformal field theory selection rules are used to find the flat directions to all orders which lead to these low-rank models and to study the relevant Yukawa couplings. A hierarchical structure of quark-lepton masses appears naturally in some models. We also present a detailed study of the structure of the Z 3 × Z 3 orbifold including the generalized GSO projection, the effect of discrete torsion and the conformal field theory Yukawa coupling selection rules. All these points are illustrated with a three-generation Z 3 × Z 3 model. We have made an effort to write a self-contained presentation in order to make this material available to non-string experts interested in the phenomenological aspects of this theory.

Highly Variable Cycle Exhaust Model Test (HVC10)

NASA Technical Reports Server (NTRS)

Henderson, Brenda; Wernet, Mark; Podboy, Gary; Bozak, Rick

2010-01-01

Results from acoustic and flow-field studies using the Highly Variable Cycle Exhaust (HVC) model were presented. The model consisted of a lobed mixer on the core stream, an elliptic nozzle on the fan stream, and an ejector. For baseline comparisons, the fan nozzle was replaced with a round nozzle and the ejector doors were removed from the model. Acoustic studies showed far-field noise levels were higher for the HVC model with the ejector than for the baseline configuration. Results from Particle Image Velocimetry (PIV) studies indicated that large flow separation regions occurred along the ejector doors, thus restricting flow through the ejector. Phased array measurements showed noise sources located near the ejector doors for operating conditions where tones were present in the acoustic spectra.

Magnetophoresis for enhancing transdermal drug delivery: Mechanistic studies and patch design

PubMed Central

Murthy, S. Narasimha; Sammeta, Srinivasa M.; Bower, C.

2017-01-01

Magnetophoresis is a method of enhancement of drug permeation across the biological barriers by application of magnetic field. The present study investigated the mechanistic aspects of magnetophoretic transdermal drug delivery and also assessed the feasibility of designing a magnetophoretic transdermal patch system for the delivery of lidocaine. In vitro drug permeation studies were carried out across the porcine epidermis at different magnetic field strengths. The magnetophoretic drug permeation “flux enhancement factor” was found to increase with the applied magnetic field strength. The mechanistic studies revealed that the magnetic field applied in this study did not modulate permeability of the stratum corneum barrier. The predominant mechanism responsible for magnetically mediated drug permeation enhancement was found to be “magnetokinesis”. The octanol/water partition coefficient of drugs was also found to increase when exposed to the magnetic field. A reservoir type transdermal patch system with a magnetic backing was designed for in vivo studies. The dermal bioavailability (AUC0–6 h) from the magnetophoretic patch system in vivo, in rats was significantly higher than the similarly designed nonmagnetic control patch. PMID:20728484

NMR at very low fields.

PubMed

Trahms, Lutz; Burghoff, Martin

2010-10-01

Although nuclear magnetic resonance in low fields around or below the Earth's magnetic field is almost as old as nuclear magnetic resonance itself, the recent years have experienced a revival of this technique that is opposed to the common trend towards higher and higher fields. The background of this development is the expectation that the low-field domain may open a new window for the study of molecular structure and dynamics. Here, we will give an overview on the specific features in the low-field domain, both from the technical and from the physical point of view. In addition, we present a short passage on the option of magnetic resonance imaging in fields of the micro-Tesla range. Copyright © 2010 Elsevier Inc. All rights reserved.

Urban High School Students' Perspectives about Sexual Health Decision-Making: The Role of School Culture and Identity

ERIC Educational Resources Information Center

Brotman, Jennie S.; Mensah, Felicia Moore

2013-01-01

Studies across fields such as science education, health education, health behavior, and curriculum studies identify a persistent gap between the aims of the school curriculum and its impact on students' thinking and acting about the real-life decisions that affect their lives. The present study presents a different story from this predominant…

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.

SU-E-T-614: Derivation of Equations to Define Inflection Points and Its Analysis in Flattening Filter Free Photon Beams Based On the Principle of Polynomial function

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

Muralidhar, K Raja; Komanduri, K

2014-06-01

Purpose: The objective of this work is to present a mechanism for calculating inflection points on profiles at various depths and field sizes and also a significant study on the percentage of doses at the inflection points for various field sizes and depths for 6XFFF and 10XFFF energy profiles. Methods: Graphical representation was done on Percentage of dose versus Inflection points. Also using the polynomial function, the authors formulated equations for calculating spot-on inflection point on the profiles for 6X FFF and 10X FFF energies for all field sizes and at various depths. Results: In a flattening filter free radiationmore » beam which is not like in Flattened beams, the dose at inflection point of the profile decreases as field size increases for 10XFFF. Whereas in 6XFFF, the dose at the inflection point initially increases up to 10x10cm2 and then decreases. The polynomial function was fitted for both FFF beams for all field sizes and depths. For small fields less than 5x5 cm2 the inflection point and FWHM are almost same and hence analysis can be done just like in FF beams. A change in 10% of dose can change the field width by 1mm. Conclusion: The present study, Derivative of equations based on the polynomial equation to define inflection point concept is precise and accurate way to derive the inflection point dose on any FFF beam profile at any depth with less than 1% accuracy. Corrections can be done in future studies based on the multiple number of machine data. Also a brief study was done to evaluate the inflection point positions with respect to dose in FFF energies for various field sizes and depths for 6XFFF and 10XFFF energy profiles.« less

Active stabilization of error field penetration via control field and bifurcation of its stable frequency range

NASA Astrophysics Data System (ADS)

Inoue, S.; Shiraishi, J.; Takechi, M.; Matsunaga, G.; Isayama, A.; Hayashi, N.; Ide, S.

2017-11-01

An active stabilization effect of a rotating control field against an error field penetration is numerically studied. We have developed a resistive magnetohydrodynamic code ‘AEOLUS-IT’, which can simulate plasma responses to rotating/static external magnetic field. Adopting non-uniform flux coordinates system, the AEOLUS-IT simulation can employ high magnetic Reynolds number condition relevant to present tokamaks. By AEOLUS-IT, we successfully clarified the stabilization mechanism of the control field against the error field penetration. Physical processes of a plasma rotation drive via the control field are demonstrated by the nonlinear simulation, which reveals that the rotation amplitude at a resonant surface is not a monotonic function of the control field frequency, but has an extremum. Consequently, two ‘bifurcated’ frequency ranges of the control field are found for the stabilization of the error field penetration.

NOTE Effects of skeletal muscle anisotropy on induced currents from low-frequency magnetic fields

NASA Astrophysics Data System (ADS)

Tachas, Nikolaos J.; Samaras, Theodoros; Baskourelos, Konstantinos; Sahalos, John N.

2009-12-01

Studies which take into account the anisotropy of tissue dielectric properties for the numerical assessment of induced currents from low-frequency magnetic fields are scarce. In the present study, we compare the induced currents in two anatomical models, using the impedance method. In the first model, we assume that all tissues have isotropic conductivity, whereas in the second one, we assume anisotropic conductivity for the skeletal muscle. Results show that tissue anisotropy should be taken into account when investigating the exposure to low-frequency magnetic fields, because it leads to higher induced current values.

Causes of forbush decreases and other cosmic ray variations

NASA Technical Reports Server (NTRS)

Barouch, E.; Burlaga, L. F.

1974-01-01

The relationship between neutron monitor variations and the intensity variations of the interplanetary magnetic field is studied, using Deep River data and IMP-series satellite data. In over 80% of the cases studied, identifiable depressions of the cosmic ray intensity are associated with magnetic field enhancements of several hours duration and intensity above 10 gamma. Conversely, each magnetic field enhancement has an identifiable effect (though not necessarily a marked depression) on the cosmic ray intensity. Long lasting Forbush decreases are found to be the consequence of the successive action of several such features. An explanation is presented and discussed.

The dynamics of zooxanthellae populations: A long-term study in the field

PubMed

Fagoonee; Wilson; Hassell; Turner

1999-02-05

Coral bleaching characterized by the expulsion of symbiotic algae (zooxanthellae) is an increasing problem worldwide. Global warming has been implicated as one cause, but the phenomenon cannot be fully comprehended without an understanding of the variability of zooxanthellae populations in field conditions. Results from a 6-year field study are presented, providing evidence of density regulation but also of large variability in the zooxanthellae population with regular episodes of very low densities. These bleaching events are likely to be part of a constant variability in zooxanthellae density caused by environmental fluctuations superimposed on a strong seasonal cycle in abundance.

Versatile generation of optical vector fields and vector beams using a non-interferometric approach.

PubMed

Tripathi, Santosh; Toussaint, Kimani C

2012-05-07

We present a versatile, non-interferometric method for generating vector fields and vector beams which can produce all the states of polarization represented on a higher-order Poincaré sphere. The versatility and non-interferometric nature of this method is expected to enable exploration of various exotic properties of vector fields and vector beams. To illustrate this, we study the propagation properties of some vector fields and find that, in general, propagation alters both their intensity and polarization distribution, and more interestingly, converts some vector fields into vector beams. In the article, we also suggest a modified Jones vector formalism to represent vector fields and vector beams.

A faint field-galaxy redshift survey in quasar fields

NASA Technical Reports Server (NTRS)

Yee, Howard K. C.; Ellingson, Erica

1993-01-01

Quasars serve as excellent markers for the identification of high-redshift galaxies and galaxy clusters. In past surveys, nearly 20 clusters of Abell richness class 1 or richer associated with quasars in the redshift range 0.2 less than z less than 0.8 were identified. In order to study these galaxy clusters in detail, a major redshift survey of faint galaxies in these fields using the CFHT LAMA/MARLIN multi-object spectroscopy system was carried out. An equally important product in such a survey is the redshifts of the field galaxies not associated with the quasars. Some preliminary results on field galaxies from an interim set of data from our redshift survey in quasar fields are presented.

ARSENIC TREATMENT TECHNOLOGY

EPA Science Inventory

Presentation will discuss the state-of-the-art technology for removal of arsenic from drinking water. Presentation also includes results of several EPA field studies on removal of arsenic from existing arsenic removal plants and key results from several EPA sponsored research st...

Intense laser field effects on a Woods-Saxon potential quantum well

NASA Astrophysics Data System (ADS)

Restrepo, R. L.; Morales, A. L.; Akimov, V.; Tulupenko, V.; Kasapoglu, E.; Ungan, F.; Duque, C. A.

2015-11-01

This paper presents the results of the theoretical study of the effects of non-resonant intense laser field and electric and magnetic fields on the optical properties in an quantum well (QW) make with Woods-Saxon potential profile. The electric field and intense laser field are applied along the growth direction of the Woods-Saxon quantum well and the magnetic field is oriented perpendicularly. To calculate the energy and the wave functions of the electron in the Woods-Saxon quantum well, the effective mass approximation and the method of envelope wave function are used. The confinement in the Woods-Saxon quantum well is changed drastically by the application of intense laser field or either the effect of electric and magnetic fields. The optical properties are calculated using the compact density matrix.

Comparison study of toroidal-field divertors for a compact reversed-field pinch reactor

NASA Astrophysics Data System (ADS)

Bathke, C. G.; Krakowski, R. A.; Miller, R. L.

Two divertor configurations for the Compact Reversed-Field Pinch Reactor (CRFPR) based on diverting the minority (toroidal) field have been reported. A critical factor in evaluating the performance of both poloidally symmetric and bundle divertor configurations is the accurate determination of the divertor connection length and the monitoring of magnetic islands introduced by the divertors, the latter being a three-dimensional effect. To this end the poloidal-field, toroidal-field, and divertor coils and the plasma currents are simulated in three dimensions for field-line trackings in both the divertor channel and the plasma-edge regions. The results of this analysis indicate a clear preference for the poloidally symmetric toroidal-field divertor. Design modifications to the limiter-based CRFPR design that accommodate this divertor are presented.

LPS-induced microvascular leukocytosis can be assessed by blue-field entoptic phenomenon.

PubMed

Kolodjaschna, Julia; Berisha, Fatmire; Lung, Solveig; Schaller, Georg; Polska, Elzbieta; Jilma, Bernd; Wolzt, Michael; Schmetterer, Leopold

2004-08-01

Administration of low doses of Escherichia coli endotoxin [a lipopolysaccharide (LPS)] to humans enables the study of inflammatory mechanisms. The purpose of the present study was to investigate whether the blue-field entoptic technique may be used to quantify the increase in circulating leukocytes in the ocular microvasculature after LPS infusion. In addition, combined laser Doppler velocimetry and retinal vessel size measurement were used to study red blood cell movement. Twelve healthy male volunteers received 20 IU/kg iv LPS as a bolus infusion. Outcome parameters were measured at baseline and 4 h after LPS administration. In the first protocol (n = 6 subjects), ocular hemodynamic effects were assessed with the blue-field entoptic technique, the retinal vessel analyzer, and laser Doppler velocimetry. In the second protocol (n = 6 subjects), white blood cell (WBC) counts from peripheral blood samples and blue-field entoptic technique measurements were performed. LPS caused peripheral blood leukocytosis and increased WBC density in ocular microvessels (by 49%; P = 0.036) but did not change WBC velocity. In addition, retinal venous diameter was increased (by 9%; P = 0.008), but red blood cell velocity remained unchanged. The LPS-induced changes in retinal WBC density and leukocyte counts were significantly correlated (r = 0.87). The present study indicates that the blue-field entoptic technique can be used to assess microvascular leukocyte recruitment in vivo. In addition, our data indicate retinal venous dilation in response to endotoxin.

Field Day at the Rec: Working Out with Physics

ERIC Educational Resources Information Center

Young, Chadwick; Young, Kaisa; Buxton, Gavin; Buzzelli, Armand

2017-01-01

Every year, thousands of college students in the life sciences take introductory physics. Some educators have advocated physics be presented in a way that is relevant to these students. Most are biology majors, but many students are in the allied health field studying to become athletic trainers, occupational therapists, or professionals in some…

THE PHYTOAVAILABILITY OF CADMIUM TO LETTUCE IN LONG-TERM BIOSOLIDS-AMENDED SOILS

EPA Science Inventory

A field study was conducted to assess the phytoavailability of Cd in long-term biosolids-amended field plots managed at high and low pH. The experiment, established 13-15 yr prior to the present cropping, on a Christiana fine sandy loam soil (a clayey, kaolinitic, mesic Typic Pa...

Reading, the Arts, and the Creation of Meaning.

ERIC Educational Resources Information Center

Eisner, Elliot W., Ed.

The seven papers that comprise this book were presented at the 1977 National Art Education Association Conference on Reading, the Arts, and the Creation of Meaning held to bring together people in the arts and the fields of reading, psychology, and philosophy to explore the relationships that exist between these fields of study. Topics discussed…

Flexible Contrast Gain Control in the Right Hemisphere

ERIC Educational Resources Information Center

Okubo, Matia; Nicholls, Michael E. R.

2005-01-01

This study investigates whether the right hemisphere has more flexible contrast gain control settings for the identification of spatial frequency. Right-handed participants identified 1 and 9 cycles per degree sinusoidal gratings presented either to the left visual field-right hemisphere (LVF-RH) or the right visual field-left hemisphere (RVF-LH).…

Rational Ignorance in Education: A Field Experiment in Student Plagiarism

ERIC Educational Resources Information Center

Dee, Thomas S.; Jacob, Brian A.

2012-01-01

Plagiarism appears to be a common problem among college students, yet there is little evidence on the effectiveness of interventions designed to minimize plagiarism. This study presents the results of a field experiment that evaluated the effects of a web-based educational tutorial in reducing plagiarism. We found that assignment to the treatment…

Bourdieu and Academic Capitalism: Faculty "Habitus" in Materials Science and Engineering

ERIC Educational Resources Information Center

Mendoza, Pilar; Kuntz, Aaron M.; Berger, Joseph B.

2012-01-01

We present Bourdieu's notions of field, capital, "habitus," and strategy and how these concepts apply today in light of academic capitalism using an empirical study of faculty work in one specific field in engineering that exemplifies current tendencies brought by academic capitalism. We conclude with a discussion of practical implications.…

Mean-field theory of spin-glasses with finite coordination number

NASA Technical Reports Server (NTRS)

Kanter, I.; Sompolinsky, H.

1987-01-01

The mean-field theory of dilute spin-glasses is studied in the limit where the average coordination number is finite. The zero-temperature phase diagram is calculated and the relationship between the spin-glass phase and the percolation transition is discussed. The present formalism is applicable also to graph optimization problems.

Higher Education: A Developing Field of Study.

ERIC Educational Resources Information Center

Harcleroad, Fred F., Ed.

This volume includes materials that clearly indicate the state of the development of the field of higher education. The members of the Association of Professors of Higher Education gathered in their third formal national conference to read and discuss the materials included here. The ideas and information presented in this edited, and relatively…

FIELD OPERATIONS AND METHODS FOR MEASURING THE ECOLOGICAL CONDITION OF NON-WADEABLE RIVERS AND STREAMS

EPA Science Inventory

The methods and instructions for field operations presented in this manual for surveys of non-wadeable streams and rivers were developed and tested based on 55 sample sites in the Mid-Atlantic region and 53 sites in an Oregon study during two years of pilot and demonstration proj...

To Stay or Not to Stay: Retention of Asian International Faculty in STEM Fields

ERIC Educational Resources Information Center

Lawrence, Janet H.; Celis, Sergio; Kim, Hee Sun; Lipson, Sarah Ketchen; Tong, Ximeng

2014-01-01

The present study identifies characteristics of individuals and work settings that influence Asian international faculty members' intentions to continue their employment in US research universities. Given the demand for researchers in science, technology, engineering and mathematics fields (STEM), the higher rate of turnover among untenured…

The magnetic field structure in high-mass star formation regions

NASA Technical Reports Server (NTRS)

Davidson, Jacqueline A.; Schleuning, D.; Dotson, J. L.; Dowell, C. Darren; Hildebrand, Roger H.

1995-01-01

We present a preliminary analysis of far-IR polarimetric observations, which were made to study the magnetic field structure in the high-mass star formation regions of M42, NGC2024, and W3. These observations were made from the Kuiper Airborne Observatory (KAO), using the University of Chicago far-IR polarimeter, Stokes.

A comparative study between nonlinear regression and artificial neural network approaches for modelling wild oat (Avena fatua) field emergence

USDA-ARS?s Scientific Manuscript database

Non-linear regression techniques are used widely to fit weed field emergence patterns to soil microclimatic indices using S-type functions. Artificial neural networks present interesting and alternative features for such modeling purposes. In this work, a univariate hydrothermal-time based Weibull m...

Olfactory Fear Conditioning Induces Field Potential Potentiation in Rat Olfactory Cortex and Amygdala

ERIC Educational Resources Information Center

Messaoudi, Belkacem; Granjon, Lionel; Mouly, Anne-Marie; Sevelinges, Yannick; Gervais, Remi

2004-01-01

The widely used Pavlovian fear-conditioning paradigms used for studying the neurobiology of learning and memory have mainly used auditory cues as conditioned stimuli (CS). The present work assessed the neural network involved in olfactory fear conditioning, using olfactory bulb stimulation-induced field potential signal (EFP) as a marker of…

FIELD EVALUATION OF A HIGH-VOLUME DICHOTOMOUS SAMPLER

EPA Science Inventory

This study presents the field evaluation of a high-volume dichotomous sampler that collects coarse (PM10-2.5) and fine (PM2.5) particulate matter. The key feature of this device is the utilization of a round-nozzle virtual impactor with a 50% cutpoint at 2.5 5m to split PM10 into...

Water Pollution Control Training: The Educational Role of the United States Environmental Protection Agency.

ERIC Educational Resources Information Center

Williams, Frederick D.

Presented are the results of a study to determine the perceived needs of environmental control education programs as seen by students, instructors, deans or program directors, and field-related employers in the field of water pollution control. Data were collected utilizing three approaches: survey instruments, information from Water Quality…

Deformation and Rotation of a Drop in a Uniform Electric Field

NASA Astrophysics Data System (ADS)

Salipante, Paul; Hanna, James; Vlahovska, Petia

2009-11-01

Drop deformation in uniform electric fields is a classic problem. The pioneering work of G.I.Taylor demonstrated that for weakly conducting media, the drop fluid undergoes a toroidal flow and the drop adopts a prolate or oblate spheroidal shape, the flow and shape being axisymmetrically aligned with the applied field. However, recent studies have revealed a nonaxisymmetric rotational mode for drops of lower conductivity than the surrounding medium, similar to the rotation of solid dielectric particles observed by Quincke in the 19th century. We will present an experimental and theoretical study of this phenomenon in DC fields. The critical electric field, drop inclination angle, and rate of rotation are measured. For small, high viscosity drops, the threshold field strength is well approximated by the Quincke rotation criterion. Reducing the viscosity ratio shifts the onset for rotation to stronger fields. The drop inclination angle increases with field strength. The rotation rate is approximately given by the inverse Maxwell-Wagner polarization time. We also observe a hysteresis in the tilt angle for low-viscosity drops. The effects of AC fields and surfactants are also explored.

Preliminary calibration plan for the Advanced Particles and Field Observatory (APAFO) magnetometer experiment

NASA Technical Reports Server (NTRS)

Voorhies, C. V.; Langel, R. A.; Slavin, J.; Lancaster, E. R.; Jones, S.

1991-01-01

Prelaunch and postlaunch calibration plans for the APAFO magnetometer experiment are presented. A study of tradeoffs between boom length and spacecraft field is described; the results are summarized. The prelaunch plan includes: calibration of the Vector Fluxgate Magnetometer (VFM), Star Sensors, and Scalar Helium Magnetometer (SHM); optical bench integration; and acquisition of basic spacecraft field data. Postlaunch calibration has two phases. In phase one, SHM data are used to calibrate the VFM, total vector magnetic field data are used to calibrate a physical model of the spacecraft field, and both calibrations are refined by iteration. In phase two, corrected vector data are transformed into geocentric coordinates, previously undetected spacecraft fields are isolated, and initial geomagnetic field models are computed. Provided the SHM is accurate to the required 1.0 nT and can be used to calibrate the VFM to the required 3.0- nT accuracy, the tradeoff study indicates that a 12 m boom and a spacecraft field model uncertainty of 5 percent together allow the 1.0 nT spacecraft field error requirement to be met.

Hysteresis in Carbon Nanotube Transistors: Measurement and Analysis of Trap Density, Energy Level, and Spatial Distribution.

PubMed

Park, Rebecca Sejung; Shulaker, Max Marcel; Hills, Gage; Suriyasena Liyanage, Luckshitha; Lee, Seunghyun; Tang, Alvin; Mitra, Subhasish; Wong, H-S Philip

2016-04-26

We present a measurement technique, which we call the Pulsed Time-Domain Measurement, for characterizing hysteresis in carbon nanotube field-effect transistors, and demonstrate its applicability for a broad range of 1D and 2D nanomaterials beyond carbon nanotubes. The Pulsed Time-Domain Measurement enables the quantification (density, energy level, and spatial distribution) of charged traps responsible for hysteresis. A physics-based model of the charge trapping process for a carbon nanotube field-effect transistor is presented and experimentally validated using the Pulsed Time-Domain Measurement. Leveraging this model, we discover a source of traps (surface traps) unique to devices with low-dimensional channels such as carbon nanotubes and nanowires (beyond interface traps which exist in today's silicon field-effect transistors). The different charge trapping mechanisms for interface traps and surface traps are studied based on their temperature dependencies. Through these advances, we are able to quantify the interface trap density for carbon nanotube field-effect transistors (∼3 × 10(13) cm(-2) eV(-1) near midgap), and compare this against a range of previously studied dielectric/semiconductor interfaces.

Geofractionation of heavy metals and application of indices for pollution prediction in paddy field soil of Tumpat, Malaysia.

PubMed

Sow, Ai Yin; Ismail, Ahmad; Zulkifli, Syaizwan Zahmir

2013-12-01

The present study investigates the concentration of Pb, Cd, Ni, Zn, and Cu in the paddy field soils collected from Tumpat, Kelantan. Soil samples were treated with sequential extraction to distinguish the anthropogenic and lithogenic origin of Pb, Cd, Ni, Zn, and Cu. ELFE and oxidizable-organic fractions were detected as the lowest accumulation of Pb, Cd, Ni, Zn, and Cu. Therefore, all the heavy metals examined were concentrated, particularly in resistant fraction, indicating that those heavy metals occurred and accumulated in an unavailable form. The utilization of agrochemical fertilizers and pesticides might not elevate the levels of heavy metals in the paddy field soils. In comparison, the enrichment factor and geoaccumulation index for Pb, Cd, Ni, Zn, and Cu suggest that these heavy metals have the potential to cause environmental risk, although they present abundance in resistant fraction. Therefore, a complete study should be conducted based on the paddy cycle, which in turn could provide a clear picture of heavy metals distribution in the paddy field soils.

Solar activity simulation and forecast with a flux-transport dynamo

NASA Astrophysics Data System (ADS)

Macario-Rojas, Alejandro; Smith, Katharine L.; Roberts, Peter C. E.

2018-06-01

We present the assessment of a diffusion-dominated mean field axisymmetric dynamo model in reproducing historical solar activity and forecast for solar cycle 25. Previous studies point to the Sun's polar magnetic field as an important proxy for solar activity prediction. Extended research using this proxy has been impeded by reduced observational data record only available from 1976. However, there is a recognised need for a solar dynamo model with ample verification over various activity scenarios to improve theoretical standards. The present study aims to explore the use of helioseismology data and reconstructed solar polar magnetic field, to foster the development of robust solar activity forecasts. The research is based on observationally inferred differential rotation morphology, as well as observed and reconstructed polar field using artificial neural network methods via the hemispheric sunspot areas record. Results show consistent reproduction of historical solar activity trends with enhanced results by introducing a precursor rise time coefficient. A weak solar cycle 25, with slow rise time and maximum activity -14.4% (±19.5%) with respect to the current cycle 24 is predicted.

Maximal near-field radiative heat transfer between two plates

NASA Astrophysics Data System (ADS)

Nefzaoui, Elyes; Ezzahri, Younès; Drévillon, Jérémie; Joulain, Karl

2013-09-01

Near-field radiative transfer is a promising way to significantly and simultaneously enhance both thermo-photovoltaic (TPV) devices power densities and efficiencies. A parametric study of Drude and Lorentz models performances in maximizing near-field radiative heat transfer between two semi-infinite planes separated by nanometric distances at room temperature is presented in this paper. Optimal parameters of these models that provide optical properties maximizing the radiative heat flux are reported and compared to real materials usually considered in similar studies, silicon carbide and heavily doped silicon in this case. Results are obtained by exact and approximate (in the extreme near-field regime and the electrostatic limit hypothesis) calculations. The two methods are compared in terms of accuracy and CPU resources consumption. Their differences are explained according to a mesoscopic description of nearfield radiative heat transfer. Finally, the frequently assumed hypothesis which states a maximal radiative heat transfer when the two semi-infinite planes are of identical materials is numerically confirmed. Its subsequent practical constraints are then discussed. Presented results enlighten relevant paths to follow in order to choose or design materials maximizing nano-TPV devices performances.

Magneto Tuning of a Ferrite Dielectric Resonator Antenna Based on LiFe5O8 Matrix

NASA Astrophysics Data System (ADS)

de Morais, J. E. V.; de Castro, A. J. N.; Oliveira, R. G. M.; do Carmo, F. F.; Sales, A. J. M.; Sales, J. C.; Silva, M. A. S.; Gouveia, D. X.; Costa, M. M.; Rodrigues, A. R.; Sombra, A. S. B.

2018-04-01

LiFe5O8 (LFO) spinel-like material has been studied for use in ferrite resonator antennas (FRAs). Antenna parameters such as gain and return loss were greatly affected when an external magnetic field was applied to the FRA. The temperature coefficient of the resonant frequency (τ f ) for the FRA presented a value of - 482.16 ppm/°C. The magnetic hysteresis results showed that the LFO was a soft ferrite, considering the values of the remanent magnetization (M r = 5.95 emu g-1), coercive field (0.76 mT), and saturation magnetization (32.15 emu g-1). The magnetodielectric resonator presented a tuning effect in the resonant frequency as a function of the external magnetic field. The antenna bandwidth was also affected by the presence of the magnetic field. LFO is a soft ferrite with applications in microwave circuits, antennas, and devices for operation at microwave frequencies due to its magnetization and demagnetization properties. Impedance study revealed increasing conductivity from room to higher temperature with low activation energy (0.36 eV).

Magnetic properties of Fe-doped organic-inorganic nanohybrids

NASA Astrophysics Data System (ADS)

Silva, N. J. O.; Amaral, V. S.; Carlos, L. D.; de Zea Bermudez, V.

2003-05-01

We present a magnetic study of Fe-doped diureasils (siloxane-based networks to which poly(ethylene oxide)-based chains are grafted by urea cross linkages doped with Fe(II) or Fe(III) ions. Structural studies show that the Fe(II) ions interact mainly with the organic chain, whereas the incorporation of Fe(III) leads to the formation of iron-based nanoclusters, with radius increasing from 20 to 40 Å. Fe(II)-doped samples behave as simple paramagnets, with μeff=5.32μB. Fe(III)-doped hybrids present antiferromagnetic interactions, with TN increasing with Fe(III) concentration up to 13.6 K for 6% doping. Thermal irreversibility was observed below ˜40 K and is stronger for higher concentrations. The coercive fields (HC) are of the order of 1000 Oe at 5 K. Hysteresis cycles are shifted to negative fields, revealing the presence of exchange anisotropy interactions with exchange fields (HE) of the order of 100 Oe. Both fields decrease rapidly with increasing temperature. We analyze this behavior in terms of the contribution of surface spin disorder to exchange anisotropy.

REBCO tape performance under high magnetic field

NASA Astrophysics Data System (ADS)

Benkel, Tara; Miyoshi, Yasuyuki; Chaud, Xavier; Badel, Arnaud; Tixador, Pascal

2017-08-01

New improvements in high temperature superconductors (HTS) make them a promising candidate for building the next generation of high field magnets. As the conductors became recently available in long length, new projects such as NOUGAT (new magnet generation to generate Tesla at low cost) were started. This project aims at designing and building an HTS magnet prototype generating 10 T inside a 20 T resistive magnet. In this configuration, severe mechanical stress is applied on the insert and its extremities are subject to a high transverse component of the field. Because the conductor has anisotropic properties, it has to be studied carefully under similar conditions as the final prototype. First, this paper presents both the NOUGAT project and its context. Then, it shows the experimental results on short HTS tapes studied under high magnetic field up to 23 T with varying orientation. These results allow validating the current margin of the prototype. Finally, a first wound prototype is presented with experimental results up to 200 A under 16 T. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2016)", edited by Adel Razek

A study of occurrence rates of Electromagnetic Interference (EMI) to aircraft with a focus on HIRF (external) High Intensity Radiated Fields

NASA Technical Reports Server (NTRS)

Shooman, Martin L.

1994-01-01

This report presents the methodology and results of a subjective study done by Polytechnic University to investigate Electromagnetic Interference (EMI) events on aircraft. The results cover various types of EMI from on-board aircraft systems, passenger carry-on devices, and externally generated disturbances. The focus of the study, however, was on externally generated EMI, termed High Intensity Radiated Fields (HIRF), from radars, radio and television transmitters, and other man-made emitters of electromagnetic energy. The study methodology used an anonymous questionnaire distributed to experts to gather the data. This method is known as the Delphi or Consensus Estimation technique. The questionnaire was sent to an expert population of 230 and there were 57 respondents. Details of the questionnaire, a few anecdotes, and the statistical results of the study are presented.

Testing memory for unseen visual stimuli in patients with extinction and spatial neglect.

PubMed

Vuilleumier, Patrik; Schwartz, Sophie; Clarke, Karen; Husain, Masud; Driver, Jon

2002-08-15

Visual extinction after right parietal damage involves a loss of awareness for stimuli in the contralesional field when presented concurrently with ipsilesional stimuli, although contralesional stimuli are still perceived if presented alone. However, extinguished stimuli can still receive some residual on-line processing, without awareness. Here we examined whether such residual processing of extinguished stimuli can produce implicit and/or explicit memory traces lasting many minutes. We tested four patients with right parietal damage and left extinction on two sessions, each including distinct study and subsequent test phases. At study, pictures of objects were shown briefly in the right, left, or both fields. Patients were asked to name them without memory instructions (Session 1) or to make an indoor/outdoor categorization and memorize them (Session 2). They extinguished most left stimuli on bilateral presentation. During the test (up to 48 min later), fragmented pictures of the previously exposed objects (or novel objects) were presented alone in either field. Patients had to identify each object and then judge whether it had previously been exposed. Identification of fragmented pictures was better for previously exposed objects that had been consciously seen and critically also for objects that had been extinguished (as compared with novel objects), with no influence of the depth of processing during study. By contrast, explicit recollection occurred only for stimuli that were consciously seen at study and increased with depth of processing. These results suggest implicit but not explicit memory for extinguished visual stimuli in parietal patients.

New Magnetic Field Model for Saturn From Cassini Radio and Magnetometers Observations: The Birotor Dipole

NASA Astrophysics Data System (ADS)

Galopeau, P. H. M.

2017-12-01

Since the insertion of Cassini in the Saturnian system in July 2004, the radio and plasma wave science (RPWS) experiment on board the spacecraft revealed the presence of two distinct and variable rotation periods in the Saturnian kilometric radiation (SKR) which were attributed to the northern and southern hemispheres respectively. The present study is based on the hypothesis that the periodic time modulations present in the SKR are mainly due to the rotation of Saturn's inner magnetic field. The existence of a double period implies that the inner field is not only limited to a simple rotation dipole but displays more complex structures having the same time periodicities than the radio emission. In order to build a model of this complex magnetic field, it is absolutely necessary to know the accurate phases of rotation linked with the two periods. The radio observations from the RPWS experiment allow a continuous and accurate follow-up of these rotation phases, since the SKR emission is permanently observable and produced very close to the planetary surface. A continuous wavelet transform analysis of the intensity of the SKR signal received at 290 kHz between July 2004 and June 2012 was performed in order to calculate in the same time the different periodicities and phases. The rotation phases associated to the main two periods allow us to define a North and South longitude system essential for such a study. In this context, a dipole model ("birotor dipole") was proposed for Saturn's inner magnetic field: this dipole presents the particularity to have North and South poles rotating around Saturn's axis at two different angular velocities; this dipole is tilted and not centered. 57 Cassini's revolutions, the periapsis of which is less than 5 Saturnian radii, have been selected for this study. For each of these chosen orbits, it is possible to fit with high precision the measurements of the MAG data experiment given by the magnetometers embarked on board Cassini. A nonrotating external magnetic field completes the model. This study suggests that Saturn's inner magnetic field is neither stationary nor fully axisymmetric. These results can be used as a boundary condition for modelling and constraining the planetary dynamo and they can be a starting point for the study of Saturn's inner structure and the comparison with the interior of Jupiter.

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

Strozzi, David J.; Perkins, L. J.; Marinak, M. M.

The effects of an imposed, axial magnetic fieldmore » $$B_{z0}$$ on hydrodynamics and energetic electrons in inertial confinement fusion indirect-drive hohlraums are studied. We present simulations from the radiation-hydrodynamics code HYDRA of a low-adiabat ignition design for the National Ignition Facility, with and without $$B_{z0}=70~\\text{T}$$. The field’s main hydrodynamic effect is to significantly reduce electron thermal conduction perpendicular to the field. This results in hotter and less dense plasma on the equator between the capsule and hohlraum wall. The inner laser beams experience less inverse bremsstrahlung absorption before reaching the wall. The X-ray drive is thus stronger from the equator with the imposed field. We study superthermal, or ‘hot’, electron dynamics with the particle-in-cell code ZUMA, using plasma conditions from HYDRA. During the early-time laser picket, hot electrons based on two-plasmon decay in the laser entrance hole (Regan et al., Phys. Plasmas, vol. 17(2), 2010, 020703) are guided to the capsule by a 70 T field. Twelve times more energy deposits in the deuterium–tritium fuel. For plasma conditions early in peak laser power, we present mono-energetic test-case studies with ZUMA as well as sources based on inner-beam stimulated Raman scattering. Furthermore, the effect of the field on deuterium–tritium deposition depends strongly on the source location, namely whether hot electrons are generated on field lines that connect to the capsule.« less

Improved detection following Neuro-Eye Therapy in patients with post-geniculate brain damage.

PubMed

Sahraie, Arash; Macleod, Mary-Joan; Trevethan, Ceri T; Robson, Siân E; Olson, John A; Callaghan, Paula; Yip, Brigitte

2010-09-01

Damage to the optic radiation or the occipital cortex results in loss of vision in the contralateral visual field, termed partial cortical blindness or hemianopia. Previously, we have demonstrated that stimulation in the field defect using visual stimuli with optimal properties for blindsight detection can lead to increases in visual sensitivity within the blind field of a group of patients. The present study was aimed to extend the previous work by investigating the effect of positive feedback on recovery of visual sensitivity. Patients' abilities for detection of a range of spatial frequencies within their field defect were determined using a temporal two-alternative forced-choice technique, before and after a period of visual training (n = 4). Patients underwent Neuro-Eye Therapy which involved detection of temporally modulated spatial grating patches at specific retinal locations within their field defect. Three patients showed improved detection ability following visual training. Based on our previous studies, we had hypothesised that should the occipital brain lesion extend anteriorly to the thalamus, little recovery would be expected. Here, we describe one such case who showed no improvements after extensive training. The present study provides further evidence that recovery (a) can be gradual and may require a large number of training sessions (b) can be accelerated using positive feedback and (c) may be less likely to take place if the occipital damage extends anteriorly to the thalamus.

Living systems in hypomagnetic conditions of Space

NASA Astrophysics Data System (ADS)

Trukhanov, Kirill; Gurieva, Tamara; Dadasheva, Olga; Spassky, Andrey; Lebedev, Viktor; Kruglov, Oleg

When working at a long-term lunar base, at stations in the near-moon space and during interplanetary missions cosmonauts will be continuously exposed to an entirely new environmental factor - hypomagnetic conditions (HMC). Interplanetary magnetic field and the field on the Lunar surface is three-five orders of magnitude below the usual geomagnetic field (GMF). It is well known that exposure to even a slightly decreased GMF adversely affect human and other living systems. Nervous, endocrine, cardiovascular systems and blood are considered to be the most sensitive to reduced GMF. There are some data in literature about the significant vulnerability of developing organism to the HMC. In this paper we present the results of further studies on the impact of the HMC on the embryogenesis of the Japanese quail (Coturnix coturnix japonica), including the works performed as the development of studies reported at the conferences COSPAR 37 and COSPAR 39. Duration of quail embryos exposure to different values of attenuation HMC (till thousandfold and more) came up to 18 days. It is shown that the prolonged exposure to the HMC heightens the adverse effects on embryogenesis. The background of alternating electromagnetic fields of the systems and equipment will exist at the habitable base or on the board of the spacecraft. The results of studies on the combined effects of HMC and weak alternating magnetic fields are also presented.

Hybrid immersed interface-immersed boundary methods for AC dielectrophoresis

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

Hossan, Mohammad Robiul; Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034-5209; Dillon, Robert

2014-08-01

Dielectrophoresis, a nonlinear electrokinetic transport mechanism, has become popular in many engineering applications including manipulation, characterization and actuation of biomaterials, particles and biological cells. In this paper, we present a hybrid immersed interface–immersed boundary method to study AC dielectrophoresis where an algorithm is developed to solve the complex Poisson equation using a real variable formulation. An immersed interface method is employed to obtain the AC electric field in a fluid media with suspended particles and an immersed boundary method is used for the fluid equations and particle transport. The convergence of the proposed algorithm as well as validation of themore » hybrid scheme with experimental results is presented. In this paper, the Maxwell stress tensor is used to calculate the dielectrophoretic force acting on particles by considering the physical effect of particles in the computational domain. Thus, this study eliminates the approximations used in point dipole methods for calculating dielectrophoretic force. A comparative study between Maxwell stress tensor and point dipole methods for computing dielectrophoretic forces are presented. The hybrid method is used to investigate the physics of dielectrophoresis in microfluidic devices using an AC electric field. The numerical results show that with proper design and appropriate selection of applied potential and frequency, global electric field minima can be obtained to facilitate multiple particle trapping by exploiting the mechanism of negative dielectrophoresis. Our numerical results also show that electrically neutral particles form a chain parallel to the applied electric field irrespective of their initial orientation when an AC electric field is applied. This proposed hybrid numerical scheme will help to better understand dielectrophoresis and to design and optimize microfluidic devices.« less

Modeling place field activity with hierarchical slow feature analysis

PubMed Central

Schönfeld, Fabian; Wiskott, Laurenz

2015-01-01

What are the computational laws of hippocampal activity? In this paper we argue for the slowness principle as a fundamental processing paradigm behind hippocampal place cell firing. We present six different studies from the experimental literature, performed with real-life rats, that we replicated in computer simulations. Each of the chosen studies allows rodents to develop stable place fields and then examines a distinct property of the established spatial encoding: adaptation to cue relocation and removal; directional dependent firing in the linear track and open field; and morphing and scaling the environment itself. Simulations are based on a hierarchical Slow Feature Analysis (SFA) network topped by a principal component analysis (ICA) output layer. The slowness principle is shown to account for the main findings of the presented experimental studies. The SFA network generates its responses using raw visual input only, which adds to its biological plausibility but requires experiments performed in light conditions. Future iterations of the model will thus have to incorporate additional information, such as path integration and grid cell activity, in order to be able to also replicate studies that take place during darkness. PMID:26052279

Models of hemispheric specialization in facial emotion perception--a reevaluation.

PubMed

Najt, Pablo; Bayer, Ulrike; Hausmann, Markus

2013-02-01

A considerable amount of research on functional cerebral asymmetries (FCAs) for facial emotion perception has shown conflicting support for three competing models: (i) the Right Hemisphere Hypothesis, (ii) the Valence-Specific Hypothesis, and (iii) the Approach/Withdrawal model. However, the majority of studies evaluating the Right Hemisphere or the Valence-Specific Hypotheses are rather limited by the small number of emotional expressions used. In addition, it is difficult to evaluate the Approach/Withdrawal Hypothesis due to insufficient data on anger and FCAs. The aim of the present study was (a) to review visual half field (VHF) studies of hemispheric specialization in facial emotion perception and (b) to reevaluate empirical evidence with respect to all three partly conflicting hypotheses. Results from the present study revealed a left visual field (LVF)/right hemisphere advantage for the perception of angry, fearful, and sad facial expressions and a right visual field (RVF)/left hemisphere advantage for the perception of happy expressions. Thus, FCAs for the perception of specific facial emotions do not fully support the Right Hemisphere Hypothesis, the Valence-Specific Hypothesis, or the Approach/Withdrawal model. A systematic literature review, together with the results of the present study, indicate a consistent LVF/right hemisphere advantage only for a subset of negative emotions including anger, fear and sadness, rather suggesting a "negative (only) valence model." PsycINFO Database Record (c) 2013 APA, all rights reserved.

Seedling growth and biomass allocation of endemic and threatened shrubs of rupestrian fields

NASA Astrophysics Data System (ADS)

Negreiros, Daniel; Fernandes, G. Wilson; Silveira, Fernando A. O.; Chalub, Clarissa

2009-03-01

The increasing anthropogenic pressure in the rare rupestrian fields in southeastern Brazil has led to the expansion of degraded areas on the extremely nutrient-deficient quartzitic soils. On the other hand, the use of rupestrian field native species in reclamation programmes has been hampered by the lack of studies involving seedling physiological ecology. The present study evaluated biomass allocation and seedling growth rate during early seedling growth of four Fabaceae shrubs: Collaea cipoensis, Calliandra fasciculata, Chamaecrista ramosa, and Mimosa foliolosa. The following hypotheses were tested: (i) species proportionally allocate higher biomass to the roots, presenting a high root/shoot ratio; and (ii) species exhibit low phenotypic variation because they have adapted to poor nutritional environments. A 12-month greenhouse experiment was carried out to evaluate seedling growth and biomass allocation performance in substrates with contrasting levels of soil fertility. The four species studied presented values of root/shoot ratio lower than one in both fertility conditions of the substrate. Growth parameters for Collaea and Calliandra increased with increasing soil fertility, while no differences were observed for Mimosa and Chamaecrista. Although the four species are naturally adapted to low nutritional quality soils, seedling development was not hindered by high fertility substrate conditions. Despite the remarkable differences in fertility between the substrates, the responsiveness in growth and allocation in Chamaecrista and Mimosa was lower than that expected if the species would exhibit high phenotypic variation. The implications for rupestrian field restoration are discussed.

Magnetic-field-induced delocalized to localized transformation in GaAs:N.

PubMed

Alberi, K; Crooker, S A; Fluegel, B; Beaton, D A; Ptak, A J; Mascarenhas, A

2013-04-12

The use of a high magnetic field (57 T) to study the formation and evolution of nitrogen (N) cluster and supercluster states in GaAs:N is demonstrated. A magnetic field is used to lift the conduction band edge and expose resonant N cluster states so that they can be directly experimentally investigated. The reduction of the exciton Bohr radius also results in the fragmentation of N supercluster states, enabling a magnetic field induced delocalized to localized transition. The application of very high magnetic fields thus presents a powerful way to probe percolation phenomena in semiconductors with bound and resonant isoelectronic cluster states.

PISCES: An Integral Field Spectrograph Technology Demonstration for the WFIRST Coronagraph

NASA Technical Reports Server (NTRS)

McElwain, Michael W.; Mandell, Avi M.; Gong, Qian; Llop-Sayson, Jorge; Brandt, Timothy; Chambers, Victor J.; Grammer, Bryan; Greeley, Bradford; Hilton, George; Perrin, Marshall D.;

PISCES: an integral field spectrograph technology demonstration for the WFIRST coronagraph

NASA Astrophysics Data System (ADS)

McElwain, Michael W.; Mandell, Avi M.; Gong, Qian; Llop-Sayson, Jorge; Brandt, Timothy; Chambers, Victor J.; Grammer, Bryan; Greeley, Bradford; Hilton, George; Perrin, Marshall D.; Stapelfeldt, Karl R.; Demers, Richard; Tang, Hong; Cady, Eric

2016-07-01

We present the design, integration, and test of the Prototype Imaging Spectrograph for Coronagraphic Exoplanet Studies (PISCES) integral field spectrograph (IFS). The PISCES design meets the science requirements for the Wide-Field InfraRed Survey Telescope (WFIRST) Coronagraph Instrument (CGI). PISCES was integrated and tested in the integral field spectroscopy laboratory at NASA Goddard. In June 2016, PISCES was delivered to the Jet Propulsion Laboratory (JPL) where it was integrated with the Shaped Pupil Coronagraph (SPC) High Contrast Imaging Testbed (HCIT). The SPC/PISCES configuration will demonstrate high contrast integral field spectroscopy as part of the WFIRST CGI technology development program.

Study of equatorial plasma bubbles using all sky imager and scintillation technique from Kolhapur station: a case study

NASA Astrophysics Data System (ADS)

Sharma, A. K.; Gurav, O. B.; Gaikwad, H. P.; Chavan, G. A.; Nade, D. P.; Nikte, S. S.; Ghodpage, R. N.; Patil, P. T.

2018-04-01

The nightglow observations of OI 630.0 nm emission carried out from low latitude station Kolhapur using All Sky Imager (ASI) with 140° field of view (FOV) for the month of April 2011 are used. The images were processed to study the field aligned irregularities often called as equatorial plasma bubbles (EPBs). The present study focuses on the occurrence of scintillation during the traversal of EPBs over ionospheric pierce point (IPP). Here we dealt with the depletion level (depth) of the EPB structures and its effect on VHF signals. We compared VHF scintillation data with airglow intensities at Ionospheric pierce point (IPP) from the same location and found that the largely depleted EPBs make stronger scintillation. From previous literature, it is believed that the small scale structures are present near the steeper walls of EPBs which often degrades the communication, the analysis presented in this paper confirms this belief.

Identifying the Tunneling Site in Strong-Field Ionization of H_{2}^{+}.

PubMed

Liu, Kunlong; Barth, Ingo

2017-12-15

The tunneling site of the electron in a molecule exposed to a strong laser field determines the initial position of the ionizing electron and, as a result, has a large impact on the subsequent ultrafast electron dynamics on the polyatomic Coulomb potential. Here, the tunneling site of the electron of H_{2}^{+} ionized by a strong circularly polarized (CP) laser pulse is studied by numerically solving the time-dependent Schrödinger equation. We show that the electron removed from the down-field site is directly driven away by the CP field and the lateral photoelectron momentum distribution (LPMD) exhibits a Gaussian-like distribution, whereas the corresponding LPMD of the electron removed from the up-field site differs from the Gaussian shape due to the Coulomb focusing and scattering by the down-field core. Our current study presents the direct evidence clarifying a long-standing controversy over the tunneling site in H_{2}^{+} and raises the important role of the tunneling site in strong-field molecular ionization.

Electrical characterization of gold-DNA-gold structures in presence of an external magnetic field by means of I-V curve analysis.

PubMed

Khatir, Nadia Mahmoudi; Banihashemian, Seyedeh Maryam; Periasamy, Vengadesh; Ritikos, Richard; Abd Majid, Wan Haliza; Abdul Rahman, Saadah

2012-01-01

This work presents an experimental study of gold-DNA-gold structures in the presence and absence of external magnetic fields with strengths less than 1,200.00 mT. The DNA strands, extracted by standard method were used to fabricate a Metal-DNA-Metal (MDM) structure. Its electric behavior when subjected to a magnetic field was studied through its current-voltage (I-V) curve. Acquisition of the I-V curve demonstrated that DNA as a semiconductor exhibits diode behavior in the MDM structure. The current versus magnetic field strength followed a decreasing trend because of a diminished mobility in the presence of a low magnetic field. This made clear that an externally imposed magnetic field would boost resistance of the MDM structure up to 1,000.00 mT and for higher magnetic field strengths we can observe an increase in potential barrier in MDM junction. The magnetic sensitivity indicates the promise of using MDM structures as potential magnetic sensors.

Electrical Characterization of Gold-DNA-Gold Structures in Presence of an External Magnetic Field by Means of I–V Curve Analysis

PubMed Central

Khatir, Nadia Mahmoudi; Banihashemian, Seyedeh Maryam; Periasamy, Vengadesh; Ritikos, Richard; Majid, Wan Haliza Abd; Rahman, Saadah Abdul

2012-01-01

This work presents an experimental study of gold-DNA-gold structures in the presence and absence of external magnetic fields with strengths less than 1,200.00 mT. The DNA strands, extracted by standard method were used to fabricate a Metal-DNA-Metal (MDM) structure. Its electric behavior when subjected to a magnetic field was studied through its current-voltage (I–V) curve. Acquisition of the I–V curve demonstrated that DNA as a semiconductor exhibits diode behavior in the MDM structure. The current versus magnetic field strength followed a decreasing trend because of a diminished mobility in the presence of a low magnetic field. This made clear that an externally imposed magnetic field would boost resistance of the MDM structure up to 1,000.00 mT and for higher magnetic field strengths we can observe an increase in potential barrier in MDM junction. The magnetic sensitivity indicates the promise of using MDM structures as potential magnetic sensors. PMID:22737025

Characteristics of Extreme Geoelectric Fields and Their Possible Causes: Localized Peak Enhancements

NASA Astrophysics Data System (ADS)

Pulkkinen, A. A.; Ngwira, C. M.; Bernabeu, E.; Eichner, J.; Viljanen, A.; Crowley, G.

2015-12-01

One of the major challenges pertaining to extreme geomagnetic storms is to understand the basic processes associated with the development of dynamic magnetosphere-ionosphere currents, which generate large induced surface geoelectric fields. Previous studies point out the existence of localized peak geoelectric field enhancements during extreme storms. We examined induced global geoelectric fields derived from ground-based magnetometer recordings for 12 extreme geomagnetic storms between the years 1982--2005. However for the present study, an in-depth analysis was performed for two important extreme storms, October 29, 2003 and March 13, 1989. The primary purpose of this paper is to provide further evidence on the existence of localized peak geoelectric field enhancements, and to show that the structure of the geoelectric field during these localized extremes at single sites can differ greatly from globally and regionally averaged fields. Although the physical processes that govern the development of these localized extremes are still not clear, we discuss some possible causes.

Effect of variable rates of daily sampling of fly larvae on decomposition and carrion insect community assembly: implications for forensic entomology field study protocols.

PubMed

Michaud, Jean-Philippe; Moreau, Gaétan

2013-07-01

Experimental protocols in forensic entomology successional field studies generally involve daily sampling of insects to document temporal changes in species composition on animal carcasses. One challenge with that method has been to adjust the sampling intensity to obtain the best representation of the community present without affecting the said community. To this date, little is known about how such investigator perturbations affect decomposition-related processes. Here, we investigated how different levels of daily sampling of fly eggs and fly larvae affected, over time, carcass decomposition rate and the carrion insect community. Results indicated that a daily sampling of <5% of the egg and larvae volumes present on a carcass, a sampling intensity believed to be consistent with current accepted practices in successional field studies, had little effect overall. Higher sampling intensities, however, slowed down carcass decomposition, affected the abundance of certain carrion insects, and caused an increase in the volume of eggs laid by dipterans. This study suggests that the carrion insect community not only has a limited resilience to recurrent perturbations but that a daily sampling intensity equal to or <5% of the egg and larvae volumes appears adequate to ensure that the system is representative of unsampled conditions. Hence we propose that this threshold be accepted as best practice in future forensic entomology successional field studies.

Insight into RF power requirements and B1 field homogeneity for human MRI via rigorous FDTD approach.

PubMed

Ibrahim, Tamer S; Tang, Lin

2007-06-01

To study the dependence of radiofrequency (RF) power deposition on B(0) field strength for different loads and excitation mechanisms. Studies were performed utilizing a finite difference time domain (FDTD) model that treats the transmit array and the load as a single system. Since it was possible to achieve homogenous excitations across the human head model by varying the amplitudes/phases of the voltages driving the transmit array, studies of the RF power/B(0) field strength (frequency) dependence were achievable under well-defined/fixed/homogenous RF excitation. Analysis illustrating the regime in which the RF power is dependent on the square of the operating frequency is presented. Detailed studies focusing on the RF power requirements as a function of number of excitation ports, driving mechanism, and orientations/positioning within the load are presented. With variable phase/amplitude excitation, as a function of frequency, the peak-then-decrease relation observed in the upper axial slices of brain with quadrature excitation becomes more evident in the lower slices as well. Additionally, homogeneity optimization targeted at minimizing the ratio of maximum/minimum B(1) (+) field intensity within the region of interest, typically results in increased RF power requirements (standard deviation was not considered in this study). Increasing the number of excitation ports, however, can result in significant RF power reduction. (c) 2007 Wiley-Liss, Inc.

Political Socialization Research and Canadian Studies

ERIC Educational Resources Information Center

Tomkins, George S.

1977-01-01

Presents a review of the burgeoning field of Canadian political socialization research as it applies to children and youth, and considers some implications of recent findings for the Canadian studies curriculum. (Editor)

Design of novel dual-port tapered waveguide plasma apparatus by numerical analysis

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

Zhang, D.; Zhou, R.; Yang, X. Q., E-mail: yyxxqq-mail@163.com

Microwave plasma apparatus is often of particular interest due to their superiority of low cost, electrode contamination free, and suitability for industrial production. However, there exist problems of unstable plasma and low electron density in conventional waveguide apparatus based on single port, due to low strength and non-uniformity of microwave field. This study proposes a novel dual-port tapered waveguide plasma apparatus based on power-combining technique, to improve the strength and uniformity of microwave field for the applications of plasma. A 3D model of microwave-induced plasma (field frequency 2.45 GHz) in argon at atmospheric pressure is presented. On the condition thatmore » the total input power is 500 W, simulations indicate that coherent power-combining will maximize the electric-field strength to 3.32 × 10{sup 5 }V/m and improve the uniformity of distributed microwave field, which raised 36.7% and 47.2%, respectively, compared to conventional waveguide apparatus of single port. To study the optimum conditions for industrial application, a 2D argon fluid model based on above structure is presented. It demonstrates that relatively uniform and high-density plasma is obtained at an argon flow rate of 200 ml/min. The contrastive result of electric-field distribution, electron density, and gas temperature is also valid and clearly proves the superiority of coherent power-combining to conventional technique in flow field.« less

Pooled analysis of recent studies on magnetic fields and childhood leukaemia

PubMed Central

Kheifets, L; Ahlbom, A; Crespi, C M; Draper, G; Hagihara, J; Lowenthal, R M; Mezei, G; Oksuzyan, S; Schüz, J; Swanson, J; Tittarelli, A; Vinceti, M; Wunsch Filho, V

2010-01-01

Background: Previous pooled analyses have reported an association between magnetic fields and childhood leukaemia. We present a pooled analysis based on primary data from studies on residential magnetic fields and childhood leukaemia published after 2000. Methods: Seven studies with a total of 10 865 cases and 12 853 controls were included. The main analysis focused on 24-h magnetic field measurements or calculated fields in residences. Results: In the combined results, risk increased with increase in exposure, but the estimates were imprecise. The odds ratios for exposure categories of 0.1–0.2 μT, 0.2–0.3 μT and ⩾0.3 μT, compared with <0.1 μT, were 1.07 (95% CI 0.81–1.41), 1.16 (0.69–1.93) and 1.44 (0.88–2.36), respectively. Without the most influential study from Brazil, the odds ratios increased somewhat. An increasing trend was also suggested by a nonparametric analysis conducted using a generalised additive model. Conclusions: Our results are in line with previous pooled analyses showing an association between magnetic fields and childhood leukaemia. Overall, the association is weaker in the most recently conducted studies, but these studies are small and lack methodological improvements needed to resolve the apparent association. We conclude that recent studies on magnetic fields and childhood leukaemia do not alter the previous assessment that magnetic fields are possibly carcinogenic. PMID:20877339

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).

Asymmetry in the Farley-Buneman dispersion relation caused by parallel electric fields

NASA Astrophysics Data System (ADS)

Forsythe, Victoriya V.; Makarevich, Roman A.

2016-11-01

An implicit assumption utilized in studies of E region plasma waves generated by the Farley-Buneman instability (FBI) is that the FBI dispersion relation and its solutions for the growth rate and phase velocity are perfectly symmetric with respect to the reversal of the wave propagation component parallel to the magnetic field. In the present study, a recently derived general dispersion relation that describes fundamental plasma instabilities in the lower ionosphere including FBI is considered and it is demonstrated that the dispersion relation is symmetric only for background electric fields that are perfectly perpendicular to the magnetic field. It is shown that parallel electric fields result in significant differences between the growth rates and phase velocities for propagation of parallel components of opposite signs. These differences are evaluated using numerical solutions of the general dispersion relation and shown to exhibit an approximately linear relationship with the parallel electric field near the E region peak altitude of 110 km. An analytic expression for the differences is also derived from an approximate version of the dispersion relation, with comparisons between numerical and analytic results agreeing near 110 km. It is further demonstrated that parallel electric fields do not change the overall symmetry when the full 3-D wave propagation vector is reversed, with no symmetry seen when either the perpendicular or parallel component is reversed. The present results indicate that moderate-to-strong parallel electric fields of 0.1-1.0 mV/m can result in experimentally measurable differences between the characteristics of plasma waves with parallel propagation components of opposite polarity.

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

Lombardo, v.; Barzi, E.; Turrioni, D.

Superconducting magnets with magnetic fields above 20 T will be needed for a Muon Collider and possible LHC energy upgrade. This field level exceeds the possibilities of traditional Low Temperature Superconductors (LTS) such as Nb{sub 3}Sn and Nb{sub 3}Al. Presently the use of high field high temperature superconductors (HTS) is the only option available for achieving such field levels. Commercially available YBCO comes in tapes and shows noticeable anisotropy with respect to field orientation, which needs to be accounted for during magnet design. In the present work, critical current test results are presented for YBCO tape manufactured by Bruker. Shortmore » sample measurements results are presented up to 14 T, assessing the level of anisotropy as a function of field, field orientation and operating temperature.« less

Remedial investigation report for J-Field, Aberdeen Proving Ground, Maryland. Volume 3: Ecological risk assessment

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

Hlohowskyj, I.; Hayse, J.; Kuperman, R.

2000-02-25

The Environmental Management Division of the U.S. Army Aberdeen Proving Ground (APG), Maryland, is conducting a remedial investigation (RI) and feasibility study (FS) of the J-Field area at APG, pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended. As part of that activity, Argonne National Laboratory (ANL) conducted an ecological risk assessment (ERA) of the J-Field site. This report presents the results of that assessment.

Imaging of acoustic fields using optical feedback interferometry.

PubMed

Bertling, Karl; Perchoux, Julien; Taimre, Thomas; Malkin, Robert; Robert, Daniel; Rakić, Aleksandar D; Bosch, Thierry

2014-12-01

This study introduces optical feedback interferometry as a simple and effective technique for the two-dimensional visualisation of acoustic fields. We present imaging results for several pressure distributions including those for progressive waves, standing waves, as well as the diffraction and interference patterns of the acoustic waves. The proposed solution has the distinct advantage of extreme optical simplicity and robustness thus opening the way to a low cost acoustic field imaging system based on mass produced laser diodes.

Influence of classical anisotropy fields on the properties of Heisenberg antiferromagnets within unified molecular field theory

DOE PAGES

Johnston, David C.

2017-12-26

Here, a comprehensive study of the influence of classical anisotropy fields on the magnetic properties of Heisenberg antiferromagnets within unified molecular field theory versus temperature T, magnetic field H, and anisotropy field parameter h A1 is presented for systems comprised of identical crystallographically-equivalent local moments. The anisotropy field for collinear z-axis antiferromagnetic (AFM) ordering is constructed so that it is aligned in the direction of each ordered and/or field-induced thermal-average moment with a magnitude proportional to the moment, whereas that for XY anisotropy is defined to be in the direction of the projection of the moment onto the xy plane,more » again with a magnitude proportional to the moment. Properties studied include the zero-field Néel temperature T N, ordered moment, heat capacity, and anisotropic magnetic susceptibility of the AFM phase versus T with moments aligned either along the z axis or in the xy plane. Also determined are the high-field magnetization perpendicular to the axis or plane of collinear or planar noncollinear AFM ordering, the high-field magnetization along the z axis of a collinear z-axis AFM, spin-flop (SF), and paramagnetic (PM) phases, and the free energies of these phases versus T, H, and h A1. Phase diagrams at T=0 in the H z– h A1 plane and at T > 0 in the H z– T plane are constructed for spins S=1/2. For h A1=0, the SF phase is stable at low field and the PM phase at high field with no AFM phase present. As h A1 increases, the phase diagram contains the AFM, SF, and PM phases. Further increases in h A1 lead to the disappearance of the SF phase and the appearance of a tricritical point on the AFM-PM transition curve. Furthermore, applications of the theory to extract h A1 from experimental low-field magnetic susceptibility data and high-field magnetization versus field isotherms for single crystals of AFMs are discussed.« less

Influence of classical anisotropy fields on the properties of Heisenberg antiferromagnets within unified molecular field theory

NASA Astrophysics Data System (ADS)

Johnston, David C.

2017-12-01

A comprehensive study of the influence of classical anisotropy fields on the magnetic properties of Heisenberg antiferromagnets within unified molecular field theory versus temperature T , magnetic field H , and anisotropy field parameter hA 1 is presented for systems comprised of identical crystallographically-equivalent local moments. The anisotropy field for collinear z -axis antiferromagnetic (AFM) ordering is constructed so that it is aligned in the direction of each ordered and/or field-induced thermal-average moment with a magnitude proportional to the moment, whereas that for XY anisotropy is defined to be in the direction of the projection of the moment onto the x y plane, again with a magnitude proportional to the moment. Properties studied include the zero-field Néel temperature TN, ordered moment, heat capacity, and anisotropic magnetic susceptibility of the AFM phase versus T with moments aligned either along the z axis or in the x y plane. Also determined are the high-field magnetization perpendicular to the axis or plane of collinear or planar noncollinear AFM ordering, the high-field magnetization along the z axis of a collinear z -axis AFM, spin-flop (SF), and paramagnetic (PM) phases, and the free energies of these phases versus T ,H , and hA 1. Phase diagrams at T =0 in the Hz-hA 1 plane and at T >0 in the Hz-T plane are constructed for spins S =1 /2 . For hA 1=0 , the SF phase is stable at low field and the PM phase at high field with no AFM phase present. As hA 1 increases, the phase diagram contains the AFM, SF, and PM phases. Further increases in hA 1 lead to the disappearance of the SF phase and the appearance of a tricritical point on the AFM-PM transition curve. Applications of the theory to extract hA 1 from experimental low-field magnetic susceptibility data and high-field magnetization versus field isotherms for single crystals of AFMs are discussed.

Influence of classical anisotropy fields on the properties of Heisenberg antiferromagnets within unified molecular field theory

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

Johnston, David C.

Here, a comprehensive study of the influence of classical anisotropy fields on the magnetic properties of Heisenberg antiferromagnets within unified molecular field theory versus temperature T, magnetic field H, and anisotropy field parameter h A1 is presented for systems comprised of identical crystallographically-equivalent local moments. The anisotropy field for collinear z-axis antiferromagnetic (AFM) ordering is constructed so that it is aligned in the direction of each ordered and/or field-induced thermal-average moment with a magnitude proportional to the moment, whereas that for XY anisotropy is defined to be in the direction of the projection of the moment onto the xy plane,more » again with a magnitude proportional to the moment. Properties studied include the zero-field Néel temperature T N, ordered moment, heat capacity, and anisotropic magnetic susceptibility of the AFM phase versus T with moments aligned either along the z axis or in the xy plane. Also determined are the high-field magnetization perpendicular to the axis or plane of collinear or planar noncollinear AFM ordering, the high-field magnetization along the z axis of a collinear z-axis AFM, spin-flop (SF), and paramagnetic (PM) phases, and the free energies of these phases versus T, H, and h A1. Phase diagrams at T=0 in the H z– h A1 plane and at T > 0 in the H z– T plane are constructed for spins S=1/2. For h A1=0, the SF phase is stable at low field and the PM phase at high field with no AFM phase present. As h A1 increases, the phase diagram contains the AFM, SF, and PM phases. Further increases in h A1 lead to the disappearance of the SF phase and the appearance of a tricritical point on the AFM-PM transition curve. Furthermore, applications of the theory to extract h A1 from experimental low-field magnetic susceptibility data and high-field magnetization versus field isotherms for single crystals of AFMs are discussed.« less

ADSORPTION MEDIA FOR ARSENIC REMOVAL

EPA Science Inventory

Presentation will discuss the use of adsorptive media for the removal of arsenic from drinking water. Presentation is a fundamental discussion on the use of adsorptive media for arsenic removal and includes information from several EPA field studies on removal of arsenic from dr...

Blade Row Interaction Effects on the Performance of a Moderately Loaded NASA Transonic Compressor Stage

NASA Technical Reports Server (NTRS)

VanZante, Dale E.; To, Wai-Ming; Chen, Jen-Ping

2003-01-01

Blade row interaction effects on loss generation in compressors have received increased attention as compressor work-per-stage and blade loading have increased. Two dimensional Laser Doppler Velocimeter measurements of the velocity field in a NASA transonic compressor stage show the magnitude of interactions in the velocity field at the peak efficiency and near stall operating conditions. The experimental data are presented along with an assessment of the velocity field interactions. In the present study the experimental data are used to confirm the fidelity of a three-dimensional, time-accurate, Navier Stokes calculation of the stage using the MSU-TURBO code at the peak efficiency and near stall operating conditions. The simulations are used to quantify the loss generation associated with interaction phenomena. At the design point the stator pressure field has minimal effect on the rotor performance. The rotor wakes do have an impact on loss production in the stator passage at both operating conditions. A method for determining the potential importance of blade row interactions on performance is presented.

Complementary analyses of hollow cylindrical unioriented permanent magnet (HCM) with high permeability external layer

NASA Astrophysics Data System (ADS)

Lobo, Carlos M. S.; Tosin, Giancarlo; Baader, Johann E.; Colnago, Luiz A.

2017-10-01

In this article, several studies based on analytical expressions and computational simulations on Hollow Cylindrical Magnets with an external soft ferromagnetic material (HCM magnets) are presented. Electromagnetic configurations, as well as permanent-magnet-based structures, are studied in terms of magnetic field strength and homogeneity. Permanent-magnet-based structures are further analyzed in terms of the anisotropy of the magnetic permeability. It was found that the HCM magnets produce a highly homogeneous magnetic field as long as the magnetic material is isotropic. The dependency of the magnetic field strength and homogeneity in terms of the anisotropy of the magnetic permeability is also explored here. These magnets can potentially be used in medium-resolution NMR spectrometers and high-field NMR spectrometers.

Entrepreneurship as a legitimate field of knowledge.

PubMed

Sánchez, José C

2011-08-01

Entrepreneurship as a research topic has been approached from disciplines such as economics, sociology or psychology. After justifying its study, we define the domain of the field, highlighting what has currently become its dominant paradigm, the process of the discovery, assessment and exploitation of opportunities. We then describe the main perspectives and offer an integrated conceptual framework that will allow us to legitimize the study of entrepreneurship as a field of knowledge in its own right. We believe that this framework will help researchers to better recognize the relations among the many factors forming part of the study of entrepreneurship. Lastly, we conclude with some brief reflections on the potential value of the framework presented.

Study of curved and planar frequency-selective surfaces with nonplanar illumination

NASA Technical Reports Server (NTRS)

Caroglanian, Armen; Webb, Kevin J.

1991-01-01

A locally planar technique (LPT) is investigated for determining the forward-scattered field from a generally shaped inductive frequency-selective surface (FSS) with nonplanar illumination. The results of an experimental study are presented to assess the LPT accuracy. The effects of a nonplanar incident field are determined by comparing the LPT numerical results with a series of experiments with the feed source placed at varying distances from the planar FSS. The limitations of the LPT model due to surface curvature are investigated in an experimental study of the scattered fields from a set of hyperbolic cylinders of different curvatures. From these comparisons, guidelines for applying the locally planar technique are developed.

[Technological education: why it is not relevant to the health field].

PubMed

Kruse, Maria Henriqueta Luce; Santana, Maria Natividade Gomes da Silva Teixeira

2002-01-01

This study discusses the National Curriculum Policies for professional education in technology, and its implementation in the health field, more especifically in the nursing field. The matter is approached from three different topics: 1) the contextualization of technological education, 2) the legal rationale, 3) the creation of human resources for SUS (Public Health system). As a conclusion, the study points out that the nursing professional would have his/her work even more fragmented than it already is. According to the study, this kind of education does not meet the needs of assistance in the present days, considering the complexity of problems related to it, the advancement of knowledge, and population growth.

Dense Velocity Field of Turkey

NASA Astrophysics Data System (ADS)

Ozener, H.; Aktug, B.; Dogru, A.; Tasci, L.

2017-12-01

While the GNSS-based crustal deformation studies in Turkey date back to early 1990s, a homogenous velocity field utilizing all the available data is still missing. Regional studies employing different site distributions, observation plans, processing software and methodology not only create reference frame variations but also heterogeneous stochastic models. While the reference frame effect between different velocity fields could easily be removed by estimating a set of rotations, the homogenization of the stochastic models of the individual velocity fields requires a more detailed analysis. Using a rigorous Variance Component Estimation (VCE) methodology, we estimated the variance factors for each of the contributing velocity fields and combined them into a single homogenous velocity field covering whole Turkey. Results show that variance factors between velocity fields including the survey mode and continuous observations can vary a few orders of magnitude. In this study, we present the most complete velocity field in Turkey rigorously combined from 20 individual velocity fields including the 146 station CORS network and totally 1072 stations. In addition, three GPS campaigns were performed along the North Anatolian Fault and Aegean Region to fill the gap between existing velocity fields. The homogenously combined new velocity field is nearly complete in terms of geographic coverage, and will serve as the basis for further analyses such as the estimation of the deformation rates and the determination of the slip rates across main fault zones.

High-Spin Structures as the Probes of Proton-Neutron Pairing

NASA Astrophysics Data System (ADS)

Afanasjev, A. V.

Rotating N = Z nuclei in the mass A = 58-80 region have been studied within the framework of isovector mean field theory. Available data is well and systematically described in the calculations. The present study supports the presence of strong isovector np pair field at low spin, which is, however, destroyed at high spin. No clear evidence for the existence of the isoscalar t = 0 np pairing has been found.

Oblique propagating electromagnetic ion - Cyclotron instability with A.C. field in outer magnetosphere

NASA Astrophysics Data System (ADS)

Pandey, R. S.; Singh, Vikrant; Rani, Anju; Varughese, George; Singh, K. M.

2018-05-01

In the present paper Oblique propagating electromagnetic ion-cyclotron wave has been analyzed for anisotropic multi ion plasma (H+, He+, O+ ions) in earth magnetosphere for the Dione shell of L=7 i.e., the outer radiation belt of the magnetosphere for Loss-cone distribution function with a spectral index j in the presence of A.C. electric field. Detail for particle trajectories and dispersion relation has been derived by using the method of characteristic solution on the basis of wave particle interaction and transformation of energy. Results for the growth rate have been calculated numerically for various parameters and have been compared for different ions present in magnetosphere. It has been found that for studying the wave over wider spectrum, anisotropy for different values of j should be taken. The effect of frequency of A.C. electric field and angle which propagation vector make with magnetic field, on growth rate has been explained.

Photoelectrons in the Quiet Polar Wind

NASA Technical Reports Server (NTRS)

Glocer, A.; Khazanov, G.; Liemohn, M.

2017-01-01

This study presents a newly coupled model capable of treating the superthermal electron population in the global polar wind solution. The model combines the hydrodynamic Polar Wind Outflow Model (PWOM) with the kinetic SuperThermal Electron Transport (STET) code. The resulting PWOM-STET coupled model is described and then used to investigate the role of photoelectrons in the polar wind. We present polar wind results along single stationary field lines under dayside and nightside conditions, as well as the global solution reconstructed from nearly 1000 moving field lines. The model results show significant day-night asymmetries in the polar wind solution owing to the higher ionization and photoelectron fluxes on the dayside compared to the nightside. Field line motion is found to modify this dependence and create global structure by transporting field lines through different conditions of illumination and through the localized effects of Joule heating.

Self-consistent simulation of radio frequency multipactor on micro-grooved dielectric surface

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

Cai, Libing; Wang, Jianguo, E-mail: wanguiuc@mail.xjtu.edu.cn; Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024

2015-02-07

The multipactor plays a key role in the surface breakdown on the feed dielectric window irradiated by high power microwave. To study the suppression of multipactor, a 2D electrostatic PIC-MCC simulation code was developed. The space charge field, including surface deposited charge and multipactor electron charge field, is obtained by solving 2D Poisson's equation in time. Therefore, the simulation is self-consistent and does not require presetting a fixed space charge field. By using this code, the self-consistent simulation of the RF multipactor on the periodic micro-grooved dielectric surface is realized. The 2D space distributions of the multipactor electrons and spacemore » charge field are presented. From the simulation results, it can be found that only half slopes have multipactor discharge when the slope angle exceeds a certain value, and the groove presents a pronounced suppression effect on the multipactor.« less

Reducing and Inducing Convection in Ge-Si Melts with Static Magnetic Field

NASA Technical Reports Server (NTRS)

Szofran, Frank R.

1999-01-01

Results of a study of the effectiveness of using static magnetic fields to reduce convection in Ge-Si melts will be presented. Lenz's law causes a retardation of convection when a static magnetic field is applied to an electrically conducting liquid. However, during the solidification of a solid-solution system such as Ge-Si, the interface is neither isothermal nor isoconcentrational. The variation of temperature and chemical composition along the interface causes thermoelectric currents to be generated within the solidifying material (and the container if it is electrically conductive). These currents, in the presence of a magnetic field, can cause movement (stirring, convection) in the melt which can exceed convection induced by normal thermosolutal mechanisms. Crystals have been grown by both the Bridgman and floating-zone methods. Clear evidence for the existence of this thermoelectromagnetic convection, especially in the case of Si floating-zone growth, will be presented.

Shallow land burial of low-level radioactive wastes. A selected, annotated bibliography

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

Fore, C.S.; Vaughan, N.D.; Tappen, J.

1978-06-01

The data file was built to provide information support to DOE researchers in the field of low-level radioactive waste disposal and management. The scope of the data base emphasizes studies which deal with the ''old'' Manhattan sites, commercial disposal sites, and the specific parameters which affect the soil and geologic migration of radionuclides. Specialized data fields have been incorporated into the data base to improve the ease and accuracy of locating pertinent references. Specific radionuclides for which data are presented are listed in the ''Measured Radionuclides'' field, and specific parameters which affect the migration of these radionuclides are presented inmore » the ''Measured Parameters'' field. The 504 references are rated indicating applicability to shallow land burial technology and whether interpretation is required. Indexes are provided for author, geographic location, title, measured parameters, measured radionuclides, keywords, subject categories, and publication description. (DLC)« less

Measurement of magnetocaloric effect in pulsed magnetic fields with the help of infrared fiber optical temperature sensor

NASA Astrophysics Data System (ADS)

Kamantsev, Alexander P.; Koledov, Victor V.; Mashirov, Alexey V.; Shavrov, Vladimir G.; Yen, N. H.; Thanh, P. T.; Quang, V. M.; Dan, N. H.; Los, Anton S.; Gilewski, Andrzej; Tereshina, Irina S.; Butvina, Leonid N.

2017-10-01

We present a new technique for experimental study of kinetics of phase transitions (PTs) and direct measurement of the magnetocaloric effect (MCE) in pulsed magnetic fields by using the fast response temperature probe with infrared fiber optical (IRFO) sensor. As demonstration of the new technique, the results are presented of MCE measurements for Gd near Curie point: ΔTad = 21.3 K under pulsed magnetic field μ0H = 12.7 T; and inverse MCE for Fe48Rh52 sample at initial temperature 305.1 K: ΔTad = -4.5 K under pulsed magnetic field μ0H = 8.5 T. Also, the energy losses on magnetization near the 1st order PT were calculated from the results of direct measurements of magnetization versus time for Fe48Rh52 sample: W = 45 J/kg.

Influence of magnetic field on chemically reactive blood flow through stenosed bifurcated arteries

NASA Astrophysics Data System (ADS)

Hossain, Khan Enaet; Haque, Md. Mohidul

2017-06-01

Dynamic response of mass transfer in chemically reactive blood flow through bifurcated arteries under the stenotic condition is numerically studied in the present of a uniform magnetic field. The blood flowing through the artery is assumed an incompressible, fully developed and Newtonian. The nonlinear unsteady flow phenomena are governed by the Navier-Stokes and concentration equations. All these equations together with the appropriate boundary conditions describing the present biomechanical problem are transformed by using a radial transformation and the numerical results are obtained using a finite difference technique. Effects of stenosed bifurcation and externally applied magnetic field on the blood flow with chemical reaction are discussed with the help of graph. All the flow characteristics are found to be affected by the presence of chemical reaction and exposure of magnetic field of different intensities. Finally some important findings of the problem are concluded in this work.

Human melatonin during continuous magnetic field exposure

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

Graham, C.; Cook, M.R.; Riffle, D.W.

This report describes the third in a series of double-blind, laboratory-based studies that were aimed at determining the effects of nocturnal exposure to power frequency magnetic fields on blood levels of melatonin in human volunteers. The two earlier studies evaluated effects on melatonin of intermittent exposure to 60 Hz circularly polarized magnetic fields at 10 and 200 mG. No overall effects on melatonin levels were found. In the present study, men were exposed continuously rather than intermittently through the night to the same 200 mG magnetic field condition that was used previously; again, no overall effects on melatonin levels weremore » found. The authors conclude that the intermittent and continuous exposure conditions used in the laboratory to date are not effective in altering nocturnal blood levels of melatonin in human volunteers.« less

Idiopathic environmental intolerance attributed to electromagnetic fields: a content analysis of British newspaper reports.

PubMed

Eldridge-Thomas, Buffy; Rubin, G James

2013-01-01

Idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) is a controversial condition in which people describe symptoms following exposure to electromagnetic fields from everyday electrical devices. However, double-blind experiments have found no convincing evidence that electromagnetic fields cause these symptoms. In this study, we assessed whether recent newspaper reporting in the UK reflected this scientific evidence. We searched a database of newspaper articles to identify all those that contained IEI-EMF related keywords and selected a random sample of 60 for content analysis. For our primary outcomes, we assessed how many articles mainly or wholly presented an electromagnetic cause for IEI-EMF and how many discussed unproven treatments for the condition such as strategies intended to reduce exposure to electromagnetic fields or the use of complementary and alternative therapies. We also assessed whether the type of information source used by a newspaper article (e.g. scientist, person with IEI-EMF, politician) or the type of newspaper (broadsheet, tabloid, local or regional) was associated with either outcome. Of the 60 articles, 43 (71.7%) presented a mainly electromagnetic cause, compared to 13 (21.7%) which presented mainly non-electromagnetic causes and 4 (6.7%) which did not discuss a cause. 29 (48.3%) did not mention any potential treatment, while 24 (40.0%) mentioned eletromagnetic field related strategies and 12 (20.0%) mentioned complementary or alternative therapies. Articles which quoted someone with IEI-EMF were significantly more likely to report an electromagnetic cause and to present unproven treatments. Those which used a scientist as a source were more likely to present a non-electromagnetic cause for the condition. The widespread poor reporting we identified is disappointing and has the potential for to encourage more people to misattribute their symptoms to electromagnetic fields. Scientists should remain engaged with the media to counteract this effect.

The mapping of the visual field onto the dorso-lateral tectum of the pigeon (Columba livia) and its relations with retinal specializations.

PubMed

Letelier, Juan-Carlos; Marin, Gonzalo; Sentis, Elisa; Tenreiro, Andrea; Fredes, Felipe; Mpodozis, Jorge

2004-01-30

Most of the physiological studies of the pigeon retino-tectal visual pathway have investigated the accessible tectum, a small dorso-lateral tectal section that can be easily accessed by a simple craniotomy. However, at present we lack a detailed study of the topographical arrangement between the visual field, the retina and the accessible tectum. In particular, it is not known which section of the visual field is mapped onto the accessible tectum, and which of the specialized retinal areas mediates this projection. Here we determined, using local field potential (LFP) recordings and reverse retinoscopy, the shape, size and position in the visual space of the portion of the visual field mapped onto the accessible tectum (called here the accessible visual field, or AVF). Using this data and the mapping of Nalbach et al. [Vis. Res. 30 (4) (1990) 529], the retinal area corresponding to the AVF was determined. Such retinal area was also directly delimited by means of retrograde transport of DiI. The results indicate that the AVF is a triangular perifoveal zone encompassing only 15% of total visual field. The retinal region corresponding to the AVF has the shape of an elongated triangle that runs parallel to the visual equator and contains the fovea, the tip of the pecten, a perifoveal region of the yellow field and a small crescent of the red field. In agreement with this anatomical heterogeneity, visual evoked potentials measured in different parts of the accessible tectum present steep variations in shape and size. These results are helpful to better design and interpret anatomical and physiological experiments involving the pigeon's visual system.

An induction heater device for studies of magnetic hyperthermia and specific absorption ratio measurements

NASA Astrophysics Data System (ADS)

Cano, M. E.; Barrera, A.; Estrada, J. C.; Hernandez, A.; Cordova, T.

2011-11-01

The development of a device for generating ac magnetic fields based on a resonant inverter is presented, which has been specially designed to carry out experiments of magnetic hyperthermia. By determining the electric current in the LC resonant circuit, a maximum intensity of magnetic field around of 15 mT is calculated, with a frequency around of 206 kHz. This ac magnetic field is able to heat powdered magnetic materials embedded in biological systems to be used in biomedical applications. Indeed, in order to evaluate the sensitivity of the device we also present the measurements of the specific absorption rate in phantoms performed with commercially prepared Fe3O4 and distilled water at different concentrations.

Numerical-Diagonalization Study of Magnetization Process of Frustrated Spin-1/2 Heisenberg Antiferromagnets in Two Dimensions: —Triangular- and Kagome-Lattice Antiferromagnets—

NASA Astrophysics Data System (ADS)

Nakano, Hiroki; Sakai, Tôru

2018-06-01

The S = 1/2 triangular- and kagome-lattice Heisenberg antiferromagnets are investigated under a magnetic field using the numerical-diagonalization method. A procedure is proposed to extract data points with very small finite-size deviations using the numerical-diagonalization results for capturing the magnetization curve. For the triangular-lattice antiferromagnet, the plateau edges at one-third the height of the saturation and the saturation field are successfully estimated. This study additionally presents results of magnetization process for a 45-site cluster of the kagome-lattice antiferromagnet; the present analysis suggests that the plateau does not open at one-ninth the height of the saturation.

Modified transverse phonon-helicon interaction in colloids laden semiconductor plasmas due to Bohm potential and Fermi degenerate pressure

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

Sharma, Aartee, E-mail: aartee.sharma08@gmail.com; Yadav, N.; Ghosh, S.

2015-07-31

A detailed study of the quantum modification of acousto-helicon wave spectra due to Bohm potential and Fermi degenerate pressure in colloids laden semiconductor plasma has been presented. We have used quantum hydrodynamic model of plasmas to arrive at most general dispersion relation in presence of magnetic field. This dispersion relation has been analyzed in three different velocity regimes and the expressions for gain constants have been obtained. From the present study it has been concluded that the quantum effect and the magnetic field significantly modify the wave characteristics particularly in high doping regime in semiconductor plasma medium in presence ofmore » colloids in it.« less

Approximate Analysis for Interlaminar Stresses in Composite Structures with Thickness Discontinuities

NASA Technical Reports Server (NTRS)

Rose, Cheryl A.; Starnes, James H., Jr.

1996-01-01

An efficient, approximate analysis for calculating complete three-dimensional stress fields near regions of geometric discontinuities in laminated composite structures is presented. An approximate three-dimensional local analysis is used to determine the detailed local response due to far-field stresses obtained from a global two-dimensional analysis. The stress results from the global analysis are used as traction boundary conditions for the local analysis. A generalized plane deformation assumption is made in the local analysis to reduce the solution domain to two dimensions. This assumption allows out-of-plane deformation to occur. The local analysis is based on the principle of minimum complementary energy and uses statically admissible stress functions that have an assumed through-the-thickness distribution. Examples are presented to illustrate the accuracy and computational efficiency of the local analysis. Comparisons of the results of the present local analysis with the corresponding results obtained from a finite element analysis and from an elasticity solution are presented. These results indicate that the present local analysis predicts the stress field accurately. Computer execution-times are also presented. The demonstrated accuracy and computational efficiency of the analysis make it well suited for parametric and design studies.

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

Ellingson, W.A.

This broad-base materials engineering program, begun in October 1974, includes studies on both ceramic (refractory) and metallic materials presently being used or intended for use in coal-conversion systems. Appropriate laboratory and field experiments are integrated such that the results have immediate impact on the present pilot-plant and proposed demonstration-plant designs. The report presents the technical accomplishments.

HARP model rotor test at the DNW. [Hughes Advanced Rotor Program

NASA Technical Reports Server (NTRS)

Dawson, Seth; Jordan, David; Smith, Charles; Ekins, James; Silverthorn, Lou

1989-01-01

Data from a test of a dynamically scaled model of the Hughes Advanced Rotor Program (HARP) bearingless model main rotor and 369K tail rotor are reported. The history of the HARP program and its goals are reviewed, and the main and tail rotor models are described. The test facilities and instrumentation are described, and wind tunnel test data are presented on hover, forward flight performance, and blade-vortex interaction. Performance data, acoustic data, and dynamic data from near field/far field and shear layer studies are presented.

Annual tendency of research papers used ICR mice as experimental animals in biomedical research fields.

PubMed

Kim, Ji Eun; Nam, Jung Hoon; Cho, Joon Young; Kim, Kil Soo; Hwang, Dae Youn

2017-06-01

Institute of Cancer Research (ICR) mice have been widely used in various research fields including toxicology, oncology, pharmacology, and pharmaceutical product safety testing for decades. However, annual tendency of research papers involving ICR mice in various biomedical fields has not been previously analyzed. In this study, we examined the numbers of papers that used ICR mice as experimental animals in the social science, natural science, engineering, medicine-pharmacy, marine agriculture-fishery, and art-kinesiology fields by analyzing big data. Numbers of ICR mouse-used papers gradually increased from 1961 to 2014, but small decreases were observed in 2015 and 2016. The largest number of ICR-used papers were published in the medicine-pharmacy field, followed by natural science and art-kinesiology fields. There were no ICR mouse-used papers in other fields. Furthermore, ICR mice have been widely employed in cell biology studies within the natural science field as well as in biochemistry and pathology in the medicine-pharmacy field. Few ICR mouse-used papers were published in exercise biochemistry and exercise nutrition in the art-kinesiology field. Regardless in most fields, the total numbers of published papers involving ICR mice were higher in 2014 than in other years, although the numbers in some fields including dentistry, veterinary science, and dermatology were high in 2016. Taken together, the present study shows that various ICR stocks, including Korl:ICR mice, are widely employed as experimental animals in various biomedical research fields.

Annual tendency of research papers used ICR mice as experimental animals in biomedical research fields

PubMed Central

Kim, Ji Eun; Nam, Jung Hoon; Cho, Joon Young; Kim, Kil Soo

2017-01-01

Institute of Cancer Research (ICR) mice have been widely used in various research fields including toxicology, oncology, pharmacology, and pharmaceutical product safety testing for decades. However, annual tendency of research papers involving ICR mice in various biomedical fields has not been previously analyzed. In this study, we examined the numbers of papers that used ICR mice as experimental animals in the social science, natural science, engineering, medicine-pharmacy, marine agriculture-fishery, and art-kinesiology fields by analyzing big data. Numbers of ICR mouse-used papers gradually increased from 1961 to 2014, but small decreases were observed in 2015 and 2016. The largest number of ICR-used papers were published in the medicine-pharmacy field, followed by natural science and art-kinesiology fields. There were no ICR mouse-used papers in other fields. Furthermore, ICR mice have been widely employed in cell biology studies within the natural science field as well as in biochemistry and pathology in the medicine-pharmacy field. Few ICR mouse-used papers were published in exercise biochemistry and exercise nutrition in the art-kinesiology field. Regardless in most fields, the total numbers of published papers involving ICR mice were higher in 2014 than in other years, although the numbers in some fields including dentistry, veterinary science, and dermatology were high in 2016. Taken together, the present study shows that various ICR stocks, including Korl:ICR mice, are widely employed as experimental animals in various biomedical research fields. PMID:28747984

New light field camera based on physical based rendering tracing

NASA Astrophysics Data System (ADS)

Chung, Ming-Han; Chang, Shan-Ching; Lee, Chih-Kung

2014-03-01

Even though light field technology was first invented more than 50 years ago, it did not gain popularity due to the limitation imposed by the computation technology. With the rapid advancement of computer technology over the last decade, the limitation has been uplifted and the light field technology quickly returns to the spotlight of the research stage. In this paper, PBRT (Physical Based Rendering Tracing) was introduced to overcome the limitation of using traditional optical simulation approach to study the light field camera technology. More specifically, traditional optical simulation approach can only present light energy distribution but typically lack the capability to present the pictures in realistic scenes. By using PBRT, which was developed to create virtual scenes, 4D light field information was obtained to conduct initial data analysis and calculation. This PBRT approach was also used to explore the light field data calculation potential in creating realistic photos. Furthermore, we integrated the optical experimental measurement results with PBRT in order to place the real measurement results into the virtually created scenes. In other words, our approach provided us with a way to establish a link of virtual scene with the real measurement results. Several images developed based on the above-mentioned approaches were analyzed and discussed to verify the pros and cons of the newly developed PBRT based light field camera technology. It will be shown that this newly developed light field camera approach can circumvent the loss of spatial resolution associated with adopting a micro-lens array in front of the image sensors. Detailed operational constraint, performance metrics, computation resources needed, etc. associated with this newly developed light field camera technique were presented in detail.

Recent advances in catchment hydrology

NASA Astrophysics Data System (ADS)

van Meerveld, I. H. J.

2017-12-01

Despite the consensus that field observations and catchment studies are imperative to understand hydrological processes, to determine the impacts of global change, to quantify the spatial and temporal variability in hydrological fluxes, and to refine and test hydrological models, there is a decline in the number of field studies. This decline and the importance of fieldwork for catchment hydrology have been described in several recent opinion papers. This presentation will summarize these commentaries, describe how catchment studies have evolved over time, and highlight the findings from selected recent studies published in Water Resources Research.

Internal Gravity Waves in the Magnetized Solar Atmosphere. I. Magnetic Field Effects

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

Vigeesh, G.; Steiner, O.; Jackiewicz, J., E-mail: vigeesh@leibniz-kis.de

Observations of the solar atmosphere show that internal gravity waves are generated by overshooting convection, but are suppressed at locations of magnetic flux, which is thought to be the result of mode conversion into magnetoacoustic waves. Here, we present a study of the acoustic-gravity wave spectrum emerging from a realistic, self-consistent simulation of solar (magneto)convection. A magnetic field free, hydrodynamic simulation and a magnetohydrodynamic (MHD) simulation with an initial, vertical, homogeneous field of 50 G flux density were carried out and compared with each other to highlight the effect of magnetic fields on the internal gravity wave propagation in themore » Sun’s atmosphere. We find that the internal gravity waves are absent or partially reflected back into the lower layers in the presence of magnetic fields and argue that the suppression is due to the coupling of internal gravity waves to slow magnetoacoustic waves still within the high- β region of the upper photosphere. The conversion to Alfvén waves is highly unlikely in our model because there is no strongly inclined magnetic field present. We argue that the suppression of internal waves observed within magnetic flux concentrations may also be due to nonlinear breaking of internal waves due to vortex flows that are ubiquitously present in the upper photosphere and the chromosphere.« less

Anisotropies in the perceived spatial displacement of motion-defined contours: opposite biases in the upper-left and lower-right visual quadrants.

PubMed

Fan, Zhao; Harris, John

2010-10-12

In a recent study (Fan, Z., & Harris, J. (2008). Perceived spatial displacement of motion-defined contours in peripheral vision. Vision Research, 48(28), 2793-2804), we demonstrated that virtual contours defined by two regions of dots moving in opposite directions were displaced perceptually in the direction of motion of the dots in the more eccentric region when the contours were viewed in the right visual field. Here, we show that the magnitude and/or direction of these displacements varies in different quadrants of the visual field. When contours were presented in the lower visual field, the direction of perceived contour displacement was consistent with that when both contours were presented in the right visual field. However, this illusory motion-induced spatial displacement disappeared when both contours were presented in the upper visual field. Also, perceived contour displacement in the direction of the more eccentric dots was larger in the right than in the left visual field, perhaps because of a hemispheric asymmetry in attentional allocation. Quadrant-based analyses suggest that the pattern of results arises from opposite directions of perceived contour displacement in the upper-left and lower-right visual quadrants, which depend on the relative strengths of two effects: a greater sensitivity to centripetal motion, and an asymmetry in the allocation of spatial attention. Copyright © 2010 Elsevier Ltd. All rights reserved.

The Development of Education in Venezuela. Bulletin, 1963, No. 7. OE-14086

ERIC Educational Resources Information Center

Sanchez, George I.

1963-01-01

The present study is one of the regular series of Office of Education bulletins presenting salient features and analysis of the educational systems of other countries. Such studies in the field of comparative education are designed to serve educators, educational institutions and organizations concerned with the planning and conduct of programs in…

Chronic detachable headphones for acoustic stimulation in freely moving animals.

PubMed

Nodal, Fernando R; Keating, Peter; King, Andrew J

2010-05-30

A growing number of studies of auditory processing are being carried out in awake, behaving animals, creating a need for precisely controlled sound delivery without restricting head movements. We have designed a system for closed-field stimulus presentation in freely moving ferrets, which comprises lightweight, adjustable headphones that can be consistently positioned over the ears via a small, skull-mounted implant. The invasiveness of the implant was minimized by simplifying its construction and using dental adhesive only for attaching it to the skull, thereby reducing the surgery required and avoiding the use of screws or other anchoring devices. Attaching the headphones to a chronic implant also reduced the amount of contact they had with the head and ears, increasing the willingness of the animals to wear them. We validated sound stimulation via the headphones in ferrets trained previously in a free-field task to localize stimuli presented from one of two loudspeakers. Noise bursts were delivered binaurally over the headphones and interaural level differences (ILDs) were introduced to allow the sound to be lateralized. Animals rapidly transferred from the free-field task to indicate the perceived location of the stimulus presented over headphones. They showed near perfect lateralization with a 5 dB ILD, matching the scores achieved in the free-field task. As expected, the ferrets' performance declined when the ILD was reduced in value. This closed-field system can easily be adapted for use in other species, and provides a reliable means of presenting closed-field stimuli whilst monitoring behavioral responses in freely moving animals. (c) 2010 Elsevier B.V. All rights reserved.

Electric and magnetic fields and tumor progression. Final report

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

Keng, P.C.; Grota, L.J.; Michaelson, S.

This laboratory study has rigorously investigated two previously reported biological effects of 60-Hz electric and magnetic fields. The first effect involves nighttime suppression of melatonin synthesis in the pineal glands of rats exposed to high electric fields. The second concerns the increase in colony forming ability of human colon cancer cells exposed to 1.4-G magnetic fields. Neither effect was detected in the present study. A series of published laboratory studies on rats reported that 60-Hz electric fields at various field levels up to 130 kV/m suppress the nighttime synthesis of melatonin, a hormone produced by the pineal gland. Since melatoninmore » is known to modulate the immune system and may inhibit cancer cell activity, changes in physiological levels of melatonin may have significant health consequences. In the repeat experiments, field exposure did not alter nighttime levels of melatonin or enzyme activities in the pineal gland. A small but statistically significant reduction of about 20% in serum melatonin was seen in exposed animals. Pineal melatonin was also unaffected by the presence of red light as a cofactor with field exposure or by time-shifting the daily field exposure period. Another study reported that 60-Hz magnetic fields can affect the colony forming ability of human cancer cells after exposure in a culture medium. In the repeat experiments, field exposure did not alter the colony forming ability of human Colo 205 cells in two different cell concentrations at plating or in two different incubation conditions. Field exposure also did not affect cell cycling in any of the four cell lines tested.« less

Magnetic particle capture for biomagnetic fluid flow in stenosed aortic bifurcation considering particle-fluid coupling

NASA Astrophysics Data System (ADS)

Bose, Sayan; Banerjee, Moloy

2015-07-01

Magnetic nanoparticles drug carriers continue to attract considerable interest for drug targeting in the treatment of cancer and other pathological conditions. Guiding magnetic iron oxide nanoparticles with the help of an external magnetic field to its target is the basic principle behind the Magnetic Drug Targeting (MDT). It is essential to couple the ferrohydrodynamic (FHD) and magnetohydrodynamic (MHD) principles when magnetic fields are applied to blood as a biomagnetic fluid. The present study is devoted to study on MDT technique by particle tracking in the presence of a non uniform magnetic field in a stenosed aortic bifurcation. The present numerical model of biomagnetic fluid dynamics (BFD) takes into accounts both magnetization and electrical conductivity of blood. The blood flow in the bifurcation is considered to be incompressible and Newtonian. An Eulerian-Lagrangian technique is adopted to resolve the hemodynamic flow and the motion of the magnetic particles in the flow using ANSYS FLUENT two way particle-fluid coupling. An implantable infinitely long cylindrical current carrying conductor is used to create the requisite magnetic field. Targeted transport of the magnetic particles in a partly occluded vessel differs distinctly from the same in a regular unblocked vessel. Results concerning the velocity and temperature field indicate that the presence of the magnetic field influences the flow field considerably and the disturbances increase as the magnetic field strength increases. The insert position is also varied to observe the variation in flow as well as temperature field. Parametric investigation is conducted and the influence of the particle size (dp), flow Reynolds number (Re) and external magnetic field strength (B0) on the "capture efficiency" (CE) is reported. The difference in CE is also studied for different particle loading condition. According to the results, the magnetic field increased the particle concentration in the target region. Analysis shows that there exists an optimum regime of operating parameters for which deposition of the drug carrying magnetic particles in a target zone on the partly occluded vessel wall can be maximized. The results provide useful design bases for in vitro set up for the investigation of MDT in stenosed blood vessels.

Dual-mode ferromagnetic resonance in an FeCoB/Ru/FeCoB synthetic antiferromagnet with uniaxial anisotropy

NASA Astrophysics Data System (ADS)

Wang, Cuiling; Zhang, Shouheng; Qiao, Shizhu; Du, Honglei; Liu, Xiaomin; Sun, Ruicong; Chu, Xian-Ming; Miao, Guo-Xing; Dai, Youyong; Kang, Shishou; Yan, Shishen; Li, Shandong

2018-05-01

Dual-mode ferromagnetic resonance is observed in FeCoB/Ru/FeCoB trilayer synthetic antiferromagnets with uniaxial in-plane magnetic anisotropy. The optical mode is present in the (0-108 Oe) magnetic field range, where the top and bottom layer magnetizations are aligned in opposite directions. The strong acoustic mode appears, when the magnetic field exceeds the 300 Oe value, which corresponds to the flop transition in the trilayer. Magnetic field and angular dependences of resonant frequencies are studied for both optical (low-field) and acoustic (high field) modes. The low-field mode is found to be anisotropic but insensitive to the magnetic field value. In contrast, the high field mode is quasi-isotropic, but its resonant frequency is tunable by the value of the magnetic field. The coexistence of two modes of ferromagnetic resonance as well as switching between them with the increase in the magnetic field originates from the difference in the sign of interlayer coupling energy at the parallel and antiparallel configurations of the synthetic antiferromagnet. The dual-mode resonance in the studied trilayer structures provides greater flexibility in the design and functionalization of micro-inductors in monolithic microwave integrated circuits.

The influence of sex hormones on functional cerebral asymmetries in postmenopausal women.

PubMed

Bayer, Ulrike; Erdmann, Gisela

2008-07-01

Studies investigating changes in functional cerebral asymmetries (FCAs) with hormonal fluctuations during the menstrual cycle in young women have led to controversial hypotheses about an influence of estrogen (E) and/or progesterone (P) on FCAs. Based on methodical, but also on principal problems in deriving conclusions about hormone effects from correlational designs, the present study investigated hemispheric asymmetries in postmenopausal women, who received hormone replacement either with E alone (E group, n=32), an E-P combination (E-P group, n=29) or no hormone substitution (control group, n=31). Speed and accuracy of responses to a word- and a face decision task, both presented laterally by means of the visual half field technique, were assessed. The control group showed the typical pattern of hemispheric asymmetry with more correct responses to verbal stimuli presented in the right visual field (RVF) and to face stimuli presented in the left visual field (LVF). A hormone-effect was demonstrable only for the verbal task, in which the E group showed an enhanced performance of the right hemisphere (LVF). The E-P group showed no significant differences to the control group or the E group. The results suggest a role of E in the modulation of FCAs at least with regard to verbal processing.

Celtic field agriculture and Early Anthropogenic Environmental change in the Meuse-Demer-Scheldt region, NW Europe

NASA Astrophysics Data System (ADS)

Van der Sanden, Germaine; Kluiving, Sjoerd; Roymans, Nico

2016-04-01

The field of Archaeology remains focused on historical issues while underexploring its potential contribution on currently existing societal problems, e.g. climate change. The aim of this paper is to show the relevance of archeological studies for the research of the 'human species as a significant moving agent' in terms of the changing natural environment during a much earlier time frame. This research is based on the study area of the Meuse-Demer-Scheldt region in the Netherlands and Belgium and exhibits the period from the Late Bronze Age to the Early Roman period. This period is characterized by the widespread introduction and use of an agricultural system, often referred to as the Celtic Field system that served as one of the most modifying systems in terms of anthropogenic-environmental change during this period. Emphasis in this research is given to results generated by the use of the remote sensing technology, LiDAR. New information is reported considering a correlation between singular field size and the overall surface of the agricultural complexes and secondly, the presentation of newly identified Celtic field systems in the Meuse-Demer-Scheldt region are presented. The study of the dynamics of the Celtic Field agricultural system provides evidence for a significant anthropogenic footprint on the natural environment due to land cover dominance, soil degeneration, increased soil acidification and forest clearance. Soil exhaustion forced the inhabitants to re-establish their relationship with the landscape in terms of fundamental changes in the habitation pattern and the agrarian exploitations of the land.

Numerical simulation of runaway electrons: 3-D effects on synchrotron radiation and impurity-based runaway current dissipation

NASA Astrophysics Data System (ADS)

del-Castillo-Negrete, D.; Carbajal, L.; Spong, D.; Izzo, V.

2018-05-01

Numerical simulations of runaway electrons (REs) with a particular emphasis on orbit dependent effects in 3-D magnetic fields are presented. The simulations were performed using the recently developed Kinetic Orbit Runaway electron Code (KORC) that computes the full-orbit relativistic dynamics in prescribed electric and magnetic fields including radiation damping and collisions. The two main problems of interest are synchrotron radiation and impurity-based RE dissipation. Synchrotron radiation is studied in axisymmetric fields and in 3-D magnetic configurations exhibiting magnetic islands and stochasticity. For passing particles in axisymmetric fields, neglecting orbit effects might underestimate or overestimate the total radiation power depending on the direction of the radial shift of the drift orbits. For trapped particles, the spatial distribution of synchrotron radiation exhibits localized "hot" spots at the tips of the banana orbits. In general, the radiation power per particle for trapped particles is higher than the power emitted by passing particles. The spatial distribution of synchrotron radiation in stochastic magnetic fields, obtained using the MHD code NIMROD, is strongly influenced by the presence of magnetic islands. 3-D magnetic fields also introduce a toroidal dependence on the synchrotron spectra, and neglecting orbit effects underestimates the total radiation power. In the presence of magnetic islands, the radiation damping of trapped particles is larger than the radiation damping of passing particles. Results modeling synchrotron emission by RE in DIII-D quiescent plasmas are also presented. The computation uses EFIT reconstructed magnetic fields and RE energy distributions fitted to the experimental measurements. Qualitative agreement is observed between the numerical simulations and the experiments for simplified RE pitch angle distributions. However, it is noted that to achieve quantitative agreement, it is necessary to use pitch angle distributions that depart from simplified 2-D Fokker-Planck equilibria. Finally, using the guiding center orbit model (KORC-GC), a preliminary study of pellet mitigated discharges in DIII-D is presented. The dependence of RE energy decay and current dissipation on initial energy and ionization levels of neon impurities is studied. The computed decay rates are within the range of experimental observations.

Field methods to evaluate effects of pesticides on wildlife of the northwestern United States

USGS Publications Warehouse

Henny, C.J.

1987-01-01

Field .methods used to evaluate the impact of organochlorine and organophosphate pesticides on wildlife populations in the Pacific Northwest are reviewed. Five field studies, presented in a CASE HISTORY format, illustrate study designs .and thetypes of information collected. The pesticides investigated included DDT, heptachlor, endr1n, and famphur, and the species studied included the American kestrel (Falco sparverius), Canada goose (Branta canadensis}, black--crowned night-heron (Nycticorax nycticorac), and black-billed magpie (Pica pica). Wildlife biologists conducting field studies of pesticides encounter a variety of design and logistics problems. However, a number of procedures are now available to the researcher for field evaluations. The three principa1 types of insecticides (organochlorines (OC's), organophosphates (OP's) and carbamates (CB's) require different field approaches. In this paper, five field studies, conducted by my colleagues and me between 1974 and 1982, in the northwestern portion of the United States (Washington, Oregon, Idaho, and northern Nevada), are reviewed to illustrate procedures for evaluating the effects of these insecticides.on wildlife populations. Althought most OC pesticides were banned in the United States during the 1970's (.for review, see F1eming et al. 1983), we studied several OC applications, including the last major DDT spray project in 1974. Use of OP's and CB's increased during the 1970's and 1980s as the OC's were phased out.

Additional road markings as an indication of speed limits: results of a field experiment and a driving simulator study.

PubMed

Daniels, Stijn; Vanrie, Jan; Dreesen, An; Brijs, Tom

2010-05-01

Although speed limits are indicated by road signs, road users are not always aware, while driving, of the actual speed limit on a given road segment. The Roads and Traffic Agency developed additional road markings in order to support driver decisions on speed on 70 km/h roads in Flanders-Belgium. In this paper the results are presented of two evaluation studies, both a field study and a simulator study, on the effects of the additional road markings on speed behaviour. The results of the field study showed no substantial effect of the markings on speed behaviour. Neither did the simulator study, with slightly different stimuli. Nevertheless an effect on lateral position was noticed in the simulator study, showing at least some effect of the markings. The role of conspicuity of design elements and expectations towards traffic environments is discussed. Both studies illustrate well some strengths and weaknesses of observational field studies compared to experimental simulator studies. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

The transverse magnetic field effect on steady-state solutions of the Bursian diode

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

Pramanik, Sourav; Chakrabarti, Nikhil; Ender, A. Ya.

2015-04-15

A study of steady-states of a planar vacuum diode driven by a cold electron beam (the Bursian diode) under an external transverse magnetic field is presented. The regime of no electrons turned around by a magnetic field only is under the consideration. The emitter electric field is evaluated as a characteristic function for the existence of solutions depending on the diode length, the applied voltage, and the magnetic field strength. At certain conditions, it is shown that a region of non-unique solutions exists in the Bursian diode when the magnetic field is absent. An expression for the maximum current transmittedmore » through the diode is derived. The external magnetic field is put forth to control fast electronic switches based on the Bursian diode.« less

[The relevance of qualitative techniques in biomedical research].

PubMed

de Camargo, Kenneth Rochel

2008-01-01

On observing how qualitative and quantitative studies are reported in the biomedical literature it becomes evident that, besides the virtual absence of the former, they are presented in different ways. Authors of qualitative studies seem to need almost invariably to explain why they choose a qualitative approach whereas that does not occur in quantitative studies. This paper takes Ludwik Fleck's comparative epistemology as a means of exploring those differences empirically, illustrating on the basis of two studies dealing with different aspects of biomedical practices how qualitative methods can elucidate a variety of questions pertaining to this field. The paper concludes presenting some structural characteristics of the biomedical field which on one hand, would not be explored properly without employing qualitative methods and, on the other hand, can help understanding the little value given to qualitative techniques in this area.

Electrohydrodynamics of drops in strong uniform dc electric fields

NASA Astrophysics Data System (ADS)

Salipante, Paul F.; Vlahovska, Petia M.

2010-11-01

Drop deformation in an uniform dc electric field is a classic problem. The pioneering work of Taylor demonstrated that for weakly conducting media, the drop fluid undergoes a toroidal flow and the drop adopts a prolate or oblate spheroidal shape, the flow and shape being axisymmetrically aligned with the applied field. However, recent studies have revealed a nonaxisymmetric rotational flow in strong fields, similar to the rotation of solid dielectric particles observed by Quincke in the 19th century. We present a systematic experimental study of this phenomenon, which highlights the importance of charge convection along the drop surface. The critical electric field, drop inclination angle, and rate of rotation are measured. We find that for small, high viscosity drops, the threshold field strength is well approximated by the Quincke rotation criterion. Reducing the viscosity ratio shifts the onset for rotation to stronger fields. The drop inclination angle increases with field strength. The rotation rate is approximately given by the inverse Maxwell-Wagner polarization time. Novel features are also observed such as a hysteresis in the tilt angle for large low-viscosity drops.

Effect of angular momentum alignment and strong magnetic fields on the formation of protostellar discs

NASA Astrophysics Data System (ADS)

Gray, William J.; McKee, Christopher F.; Klein, Richard I.

2018-01-01

Star-forming molecular clouds are observed to be both highly magnetized and turbulent. Consequently, the formation of protostellar discs is largely dependent on the complex interaction between gravity, magnetic fields, and turbulence. Studies of non-turbulent protostellar disc formation with realistic magnetic fields have shown that these fields are efficient in removing angular momentum from the forming discs, preventing their formation. However, once turbulence is included, discs can form in even highly magnetized clouds, although the precise mechanism remains uncertain. Here, we present several high-resolution simulations of turbulent, realistically magnetized, high-mass molecular clouds with both aligned and random turbulence to study the role that turbulence, misalignment, and magnetic fields have on the formation of protostellar discs. We find that when the turbulence is artificially aligned so that the angular momentum is parallel to the initial uniform field, no rotationally supported discs are formed, regardless of the initial turbulent energy. We conclude that turbulence and the associated misalignment between the angular momentum and the magnetic field are crucial in the formation of protostellar discs in the presence of realistic magnetic fields.

Nonsequential double ionization with mid-infrared laser fields

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

Li, Ying -Bin; Wang, Xu; Yu, Ben -Hai

Using a full-dimensional Monte Carlo classical ensemble method, we present a theoretical study of atomic nonsequential double ionization (NSDI) with mid-infrared laser fields, and compare with results from near-infrared laser fields. Unlike single-electron strong-field processes, double ionization shows complex and unexpected interplays between the returning electron and its parent ion core. As a result of these interplays, NSDI for mid-IR fields is dominated by second-returning electron trajectories, instead of first-returning trajectories for near-IR fields. Here, some complex NSDI channels commonly happen with near-IR fields, such as the recollision-excitation-with-subsequent-ionization (RESI) channel, are virtually shut down by mid-IR fields. Besides, the finalmore » energies of the two electrons can be extremely unequal, leading to novel e-e momentum correlation spectra that can be measured experimentally.« less

Nonsequential double ionization with mid-infrared laser fields

DOE PAGES

Li, Ying -Bin; Wang, Xu; Yu, Ben -Hai; ...

2016-11-18

Using a full-dimensional Monte Carlo classical ensemble method, we present a theoretical study of atomic nonsequential double ionization (NSDI) with mid-infrared laser fields, and compare with results from near-infrared laser fields. Unlike single-electron strong-field processes, double ionization shows complex and unexpected interplays between the returning electron and its parent ion core. As a result of these interplays, NSDI for mid-IR fields is dominated by second-returning electron trajectories, instead of first-returning trajectories for near-IR fields. Here, some complex NSDI channels commonly happen with near-IR fields, such as the recollision-excitation-with-subsequent-ionization (RESI) channel, are virtually shut down by mid-IR fields. Besides, the finalmore » energies of the two electrons can be extremely unequal, leading to novel e-e momentum correlation spectra that can be measured experimentally.« less

Evaluation of the Persistent Issues in History Laboratory for Virtual Field Experience (PIH-LVFE)

ERIC Educational Resources Information Center

Brush, Thomas; Saye, John; Kale, Ugur; Hur, Jung Won; Kohlmeier, Jada; Yerasimou, Theano; Guo, Lijiang; Symonette, Simone

2009-01-01

The Persistent Issues in History Laboratory for Virtual Field Experience (PIH-LVFE) combines a database of video cases of authentic classroom practices with multiple resources and tools to enable pre-service social studies teachers to virtually observe teachers implementing problem-based learning activities. In this paper, we present the results…