Career-focused field trips as experienced by at-risk rural students: A case study

NASA Astrophysics Data System (ADS)

Hutson, Tommye L.

A lack of recent research focused on field trips as pedagogy in K-12 settings established the foundation for this work. The research design followed multiple-case case study model. The participants were four male students from a small rural high school in central Texas. Each participant, previously labeled as academically "at-risk", had identified an inability to describe connections between academic science content as presented in their common classes and future jobs, vocational training, and/or careers requiring higher education. Because the participants had no directed field excursions addressing this desirable knowledge and/or skill, a career-focused field trip was designed to address the self-identified deficit reported by the participants. The specific research questions were: (1) How does the ability to describe connections between academic science content (biology, chemistry, and physics) and future careers change as rural students experience a purposeful excursion to a post-secondary facility providing vocational training? (2) When do the connection(s) between content and future careers become evident to students? (3) What effects or impact do newly discovered connections have on rural students' aspirations with regard to future career or higher education options? Data were gathered using existing school records, an initial survey, one-to-one interviews conducted before and after the field trip, focus groups conducted before and after the field trip, and observations during the field trip. Data analysis revealed that all participants were able to describe various connections between academic content and careers after the field trip, as well as identify a specific incident that initially established those connections. In addition, all of the participants reported discovering options for careers during the field trip not previously realized or considered. Each participant indicated that they found field trips to be effective. As a result of their singular experience, they collectively voiced a belief that career-focused field trips should be included in all required science classes starting in late middle school and continuing through at least the 10th grade.

Geohazards Graduate Study With the U.S. Peace Corps

NASA Astrophysics Data System (ADS)

Rose, William I.; Bluth, Gregg J. S.

A unique, new educational program that focuses on geological natural hazards, U.S. Peace Corps field work, and on-campus study has begun its second year at Michigan Technological University, in Houghton, Michigan.While “Masters International” programs that combine Peace Corps service with a graduate degree program are available at 49 different universities in a variety of fields, the program at Michigan Tech is the only one with a natural hazards focus offering geological degree programs.

Development and field testing of a smartphone "App" for tinnitus management.

PubMed

Henry, James A; Thielman, Emily; Zaugg, Tara; Kaelin, Christine; Choma, Christie; Chang, Bill; Hahn, Shira; Fuller, Bret

2017-10-01

This study's objective was to develop and test a smartphone app that supports learning and using coping skills for managing tinnitus. The app's content was based on coping skills that are taught as a part of progressive tinnitus management (PTM). The study involved three phases: (1) develop a prototype app and conduct usability testing; (2) conduct two focus groups to obtain initial feedback from individuals representing potential users; and (3) conduct a field study to evaluate the app, with three successive groups of participants. Participants were adults with bothersome tinnitus. For Phase 2, two focus groups were attended by a total of 17 participants. Phase 3 involved three consecutive rounds of participants: five from the focus groups followed by two rounds with 10 participants each who had not seen the app previously. In both the focus groups and field studies, participants responded favourably to the content. Certain features, however, were deemed too complex. Completion of this project resulted in the development and testing of the delivery of PTM coping skills via a smartphone app. This new approach has the potential to improve access to coping skills for those with bothersome tinnitus.

Teachers as Secondary Players: Involvement in Field Trips to Natural Environments

ERIC Educational Resources Information Center

Alon, Nirit Lavie; Tal, Tali

2017-01-01

This study focused on field trips to natural environments where the teacher plays a secondary role alongside a professional guide. We investigated teachers' and field trip guides' views of the teacher's role, the teacher's actual function on the field trip, and the relationship between them. We observed field trips, interviewed teachers and…

Focusing and depth of field in photography: application in dermatology practice.

PubMed

Taheri, Arash; Yentzer, Brad A; Feldman, Steven R

2013-11-01

Conventional photography obtains a sharp image of objects within a given 'depth of field'; objects not within the depth of field are out of focus. In recent years, digital photography revolutionized the way pictures are taken, edited, and stored. However, digital photography does not result in a deeper depth of field or better focusing. In this article, we briefly review the concept of depth of field and focus in photography as well as new technologies in this area. A deep depth of field is used to have more objects in focus; a shallow depth of field can emphasize a subject by blurring the foreground and background objects. The depth of field can be manipulated by adjusting the aperture size of the camera, with smaller apertures increasing the depth of field at the cost of lower levels of light capture. Light-field cameras are a new generation of digital cameras that offer several new features, including the ability to change the focus on any object in the image after taking the photograph. Understanding depth of field and camera technology helps dermatologists to capture their subjects in focus more efficiently. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Solenoid Fringe Field Effects for the Neutrino Factory Linac - MAD-X Investigation

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

M. Aslaninejad,C. Bontoiu,J. Pasternak,J. Pozimski,Alex Bogacz

2010-05-01

International Design Study for the Neutrino Factory (IDS-NF) assumes the first stage of muon acceleration (up to 900 MeV) to be implemented with a solenoid based Linac. The Linac consists of three styles of cryo-modules, containing focusing solenoids and varying number of SRF cavities for acceleration. Fringe fields of the solenoids and the focusing effects in the SRF cavities have significant impact on the transverse beam dynamics. Using an analytical formula, the effects of fringe fields are studied in MAD-X. The resulting betatron functions are compared with the results of beam dynamics simulations using OptiM code.

Light focusing through a multiple scattering medium: ab initio computer simulation

NASA Astrophysics Data System (ADS)

Danko, Oleksandr; Danko, Volodymyr; Kovalenko, Andrey

2018-01-01

The present study considers ab initio computer simulation of the light focusing through a complex scattering medium. The focusing is performed by shaping the incident light beam in order to obtain a small focused spot on the opposite side of the scattering layer. MSTM software (Auburn University) is used to simulate the propagation of an arbitrary monochromatic Gaussian beam and obtain 2D distribution of the optical field in the selected plane of the investigated volume. Based on the set of incident and scattered fields, the pair of right and left eigen bases and corresponding singular values were calculated. The pair of right and left eigen modes together with the corresponding singular value constitute the transmittance eigen channel of the disordered media. Thus, the scattering process is described in three steps: 1) initial field decomposition in the right eigen basis; 2) scaling of decomposition coefficients for the corresponding singular values; 3) assembling of the scattered field as the composition of the weighted left eigen modes. Basis fields are represented as a linear combination of the original Gaussian beams and scattered fields. It was demonstrated that 60 independent control channels provide focusing the light into a spot with the minimal radius of approximately 0.4 μm at half maximum. The intensity enhancement in the focal plane was equal to 68 that coincided with theoretical prediction.

International Baccalaureate Diploma Programs (IBDP) in Oklahoma: A Mixed Methods Study

ERIC Educational Resources Information Center

Hood, Susan J.

2012-01-01

Scope and Method of Study: As Oklahoma grows in technical markets, the need for science, technology, engineering, and mathematics (STEM) educated individuals will continue to increase. Our focus in aviation should be at focusing to attract students into STEM related fields, however, a stronger focus needs to be in retaining the top tier category…

Doctoral Student Attrition in the STEM Fields: An Exploratory Event History Analysis

ERIC Educational Resources Information Center

Lott, Joe L., II; Gardner, Susan; Powers, Daniel A.

2010-01-01

The STEM fields, otherwise known as the Sciences, Technology, Engineering, and Mathematics areas, have become the focus of multiple studies and funding initiatives in recent years. Despite these efforts, lingering concerns exist about who enters, who is retained, and who completes the doctorate in STEM fields. This study utilizes discrete-time…

Examining the Content of Preservice Teachers' Reflections of Early Field Experiences

ERIC Educational Resources Information Center

Subramaniam, Karthigeyan

2013-01-01

This paper describes an exploratory study that examined the content of preservice elementary teachers' reflections of their documented early field experiences of science teaching in authentic contexts. The study used an early field experience model that was focused on the objective of profiling an elementary science teacher as the practical…

Gamma-ray generation in the interaction of two tightly focused laser pulses with a low-density target composed of electrons

NASA Astrophysics Data System (ADS)

Jirka, M.; Klimo, O.; Weber, S.; Bulanov, Sergei V.; Esirkepov, Timur Zh.; Korn, G.

2015-05-01

With the continuing development of laser systems, new important and so-far unexplored fields of research related to interaction of ultra-intense laser beams with matter are opening. At intensities of the order of 1022 W=cm2, electrons may be accelerated in the electromagnetic field of the laser wave and achieve such a high energy that they can enter the regime affected by the radiation reaction. Due to the non-linear Thomson and Compton scattering the accelerated electrons emit photons. The interaction of emitted photons with the laser field may result in effective generation of electron-positron pairs by means of the Breit-Wheeler process. In this work we study the influence of laser pulse polarization on gamma-ray generation during interaction of two colliding and tightly focused laser pulses with a low density target composed of electrons. This paper focuses on evolution of electron trajectories and key parameters χe (probability of photon emission) and χγ(probability of pair generation) in the laser field. These interactions are studied using 2D PIC simulations. It is shown that in the case of circularly polarized and tightly focused laser beams, electrons are not following circular trajectories at the magnetic node of the standing wave established in the focus, which leads to lowering the radiation emission efficiency.

Academic Job Placements in Library and Information Science Field: A Case Study Performed on ALISE Web-Based Postings

ERIC Educational Resources Information Center

Abouserie, Hossam Eldin Mohamed Refaat

2010-01-01

The study investigated and analyzed the state of academic web-based job announcements in Library and Information Science Field. The purpose of study was to get in depth understanding about main characteristics and trends of academic job market in Library and Information science field. The study focused on web-based version announcement as it was…

Policy Forum: Studying Eyewitness Investigations in the Field

PubMed Central

Dawes, Robyn; Jacoby, Larry L.; Kahneman, Daniel; Lempert, Richard; Roediger, Henry L.; Rosenthal, Robert

2007-01-01

This article considers methodological issues arising from recent efforts to provide field tests of eyewitness identification procedures. We focus in particular on a field study (Mecklenburg 2006) that examined the “double blind, sequential” technique, and consider the implications of an acknowledged methodological confound in the study. We explain why the confound has severe consequences for assessing the real-world implications of this study. PMID:17610149

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…

Dynamics of laser-driven proton beam focusing and transport into solid density matter

NASA Astrophysics Data System (ADS)

Kim, J.; McGuffey, C.; Beg, F.; Wei, M.; Mariscal, D.; Chen, S.; Fuchs, J.

2016-10-01

Isochoric heating and local energy deposition capabilities make intense proton beams appealing for studying high energy density physics and the Fast Ignition of inertial confinement fusion. To study proton beam focusing that results in high beam density, experiments have been conducted using different target geometries irradiated by a kilojoule, 10 ps pulse of the OMEGA EP laser. The beam focus was measured by imaging beam-induced Cu K-alpha emission on a Cu foil that was positioned at a fixed distance. Compared to a free target, structured targets having shapes of wedge and cone show a brighter and narrower K-alpha radiation emission spot on a Cu foil indicating higher beam focusability. Experimentally observed images with proton radiography demonstrate the existence of transverse fields on the structures. Full-scale simulations including the contribution of a long pulse duration of the laser confirm that such fields can be caused by hot electrons moving through the structures. The simulated fields are strong enough to reflect the diverging main proton beam and pinch a transverse probe beam. Detailed simulation results including the beam focusing and transport of the focused intense proton beam in Cu foil will be presented. This work was supported by the National Laser User Facility Program through Award DE-NA0002034.

Sonochemiluminescence observation of lipid- and polymer-shelled ultrasound contrast agents in 1.2 MHz focused ultrasound field.

PubMed

Qiao, Yangzi; Cao, Hua; Zhang, Shusheng; Yin, Hui; Wan, Mingxi

2013-01-01

Ultrasound contrast agents (UCAs) are frequently added into the focused ultrasound field as cavitation nuclei to enhance the therapeutic efficiency. Since their presence will distort the pressure field and make the process unpredictable, comprehension of their behaviors especially the active zone spatial distribution is an important part of better monitoring and using of UCAs. As shell materials can strongly alter the acoustic behavior of UCAs, two different shells coated UCAs, lipid-shelled and polymer-shelled UCAs, in a 1.2 MHz focused ultrasound field were studied by the Sonochemiluminescence (SCL) method and compared. The SCL spatial distribution of lipid-shelled group differed from that of polymer-shelled group. The shell material and the character of focused ultrasound field work together to the SCL distribution, causing the lipid-shelled group to have a maximum SCL intensity in pre-focal region at lower input power than that of polymer-shelled group, and a brighter SCL intensity in post-focal region at high input power. The SCL inactive area of these two groups both increased with the input power. The general behavior of the UCAs can be studied by both the average SCL intensity and the backscatter signals. As polymer-shelled UCAs are more resistant to acoustic pressure, they had a higher destruction power and showed less reactivation than lipid-shelled ones. Copyright © 2012 Elsevier B.V. All rights reserved.

A Tilted Plane as a Gravitational Field Model.

ERIC Educational Resources Information Center

Hale, D. P.

1980-01-01

Describes an experiment for the use of a tilted plane as a two-dimensional uniform gravitational field to demonstrate the motion of projectiles, to determine the fundamental laws of mechanics, or to study the focusing properties of the uniform field. (SK)

Cross-cutting study of advanced rural transportation system ITS field operational tests

DOT National Transportation Integrated Search

1998-08-01

USDOT has funded seven Advanced Rural Transportation System (ARTS) projects focused on traveler safety under the ITS Field Operational Test Program. Booz-Allen & Hamilton was contracted to oversee the evaluation of these (as well as 50+ other) field ...

Field characteristics of an alvarez-type linac structure having chain-like electrode array

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

Odera, M.; Goto, A.; Hemmi, M.

1985-10-01

A chain-like electrode configuration in an Alvarez-type linac cavity was studied by models. The structure has been devised to get a moderate shunt impedance together with simplicity of operation, in ion velocity region of more than a few percent of that of light by incorporating focusing scheme by high frequency quadrupolar fields into an TM-010 accelerating field of an Alvarez linac. It has a chain-like electrode array instead of drift tubes containing quadrupole lenses for ordinary linacs. The chain-like electrode structure generates along its central axis, high frequency acceleration and focusing fields alternately, separating the acceleration and focusing functions inmore » space. The separation discriminates this structure from spatially uniform acceleration and focusing scheme of the RFQs devised by Kapchinsky and Teplyakov. It gives beam acceleration effects different from those by conventional linacs and reveals possibility of getting a high acceleration efficiency. Resonant frequency spectrum was found relatively simple by measurements on high frequency models. Separation of unwanted modes from the TM-010 acceleration mode is large; a few 10 MHz, at least. Tilt of the acceleration field is not very sensitive to pertubation in gap capacitance for the TM-010 mode.« less

The past, present and future of social neuroscience: a European perspective.

PubMed

Singer, Tania

2012-06-01

This review provides an overview of the field of social neuroscience from a European perspective and focuses mainly on outlining research topics which originated in European laboratories. After a brief historical synopsis of the emergence of this young field, the most relevant findings related to the investigation of the neural networks underlying our capacity to understand the minds of others are summarized. More specifically, three routes of social cognition are distinguished: (1) our capacity to mentalize, or to infer intentions and beliefs of others, (2) our capacity to mimic and understand other's motor actions, and (3) our capacity to empathize, or to share and understand the feelings of others. More recent studies focusing on social emotions such as love, compassion, revenge or our sense of fairness will be discussed linking the field of social neuroscience to the even younger field of neuroeconomics, with the focus on the study of human social interactions using game theoretical paradigms. Finally, the use of a multi-method and multi-disciplinary research approach combining genetic, pharmacological, computational and developmental aspects is advocated and future directions for the study of interactive minds are discussed. Copyright © 2012 Elsevier Inc. All rights reserved.

Meet EPA Chemist Quincy Teng, Ph.D.

EPA Pesticide Factsheets

EPA research chemist Quincy Teng, Ph.D., focuses on the application of metabolomics—a relatively new, specialized field of biochemistry focused on studying small molecules known as metabolites—on environmental and life sciences.

Changes in the distribution of sustained attention alter the perceived structure of visual space.

PubMed

Fortenbaugh, Francesca C; Robertson, Lynn C; Esterman, Michael

2017-02-01

Visual spatial attention is a critical process that allows for the selection and enhanced processing of relevant objects and locations. While studies have shown attentional modulations of perceived location and the representation of distance information across multiple objects, there remains disagreement regarding what influence spatial attention has on the underlying structure of visual space. The present study utilized a method of magnitude estimation in which participants must judge the location of briefly presented targets within the boundaries of their individual visual fields in the absence of any other objects or boundaries. Spatial uncertainty of target locations was used to assess perceived locations across distributed and focused attention conditions without the use of external stimuli, such as visual cues. Across two experiments we tested locations along the cardinal and 45° oblique axes. We demonstrate that focusing attention within a region of space can expand the perceived size of visual space; even in cases where doing so makes performance less accurate. Moreover, the results of the present studies show that when fixation is actively maintained, focusing attention along a visual axis leads to an asymmetrical stretching of visual space that is predominantly focused across the central half of the visual field, consistent with an expansive gradient along the focus of voluntary attention. These results demonstrate that focusing sustained attention peripherally during active fixation leads to an asymmetrical expansion of visual space within the central visual field. Published by Elsevier Ltd.

Jupiter Environmental Research & Field Studies Academy.

ERIC Educational Resources Information Center

Huttemeyer, Bob

1996-01-01

Describes the development and workings of the Jupiter Environmental Research and Field Studies Academy that focuses on enabling both teachers and students to participate in real-life learning experiences. Discusses qualifications for admittance, curriculum, location, ongoing projects, students, academics, preparation for life, problem solving, and…

Investigating the Transition Process when Moving from a Spiral Curriculum Alignment into a Field-Focus Science Curriculum Alignment in Middle School

ERIC Educational Resources Information Center

Alwardt, Randi Kay

2011-01-01

This investigation examined the transition from a spiral science curriculum to a field-focus science curriculum in middle school. A spiral science curriculum focuses on a small part of each field of science during each middle school year, more of a general science concept. In contrast to that, the base of a field-focus curriculum is that each…

[A focused sound field measurement system by LabVIEW].

PubMed

Jiang, Zhan; Bai, Jingfeng; Yu, Ying

2014-05-01

In this paper, according to the requirement of the focused sound field measurement, a focused sound field measurement system was established based on the LabVIEW virtual instrument platform. The system can automatically search the focus position of the sound field, and adjust the scanning path according to the size of the focal region. Three-dimensional sound field scanning time reduced from 888 hours in uniform step to 9.25 hours in variable step. The efficiency of the focused sound field measurement was improved. There is a certain deviation between measurement results and theoretical calculation results. Focal plane--6 dB width difference rate was 3.691%, the beam axis--6 dB length differences rate was 12.937%.

Nanoscale Probing of Thermal, Stress, and Optical Fields under Near-Field Laser Heating

PubMed Central

Tang, Xiaoduan; Xu, Shen; Wang, Xinwei

2013-01-01

Micro/nanoparticle induced near-field laser ultra-focusing and heating has been widely used in laser-assisted nanopatterning and nanolithography to pattern nanoscale features on a large-area substrate. Knowledge of the temperature and stress in the nanoscale near-field heating region is critical for process control and optimization. At present, probing of the nanoscale temperature, stress, and optical fields remains a great challenge since the heating area is very small (∼100 nm or less) and not immediately accessible for sensing. In this work, we report the first experimental study on nanoscale mapping of particle-induced thermal, stress, and optical fields by using a single laser for both near-field excitation and Raman probing. The mapping results based on Raman intensity variation, wavenumber shift, and linewidth broadening all give consistent conjugated thermal, stress, and near-field focusing effects at a 20 nm resolution (<λ/26, λ = 32 nm). Nanoscale mapping of near-field effects of particles from 1210 down to 160 nm demonstrates the strong capacity of such a technique. By developing a new strategy for physical analysis, we have de-conjugated the effects of temperature, stress, and near-field focusing from the Raman mapping. The temperature rise and stress in the nanoscale heating region is evaluated at different energy levels. High-fidelity electromagnetic and temperature field simulation is conducted to accurately interpret the experimental results. PMID:23555566

Broadband reflective metasurface for focusing underwater ultrasonic waves with linearly tunable focal length

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

Wu, Xiaoxiao; Tian, Jingxuan; Wen, Weijia, E-mail: phwen@ust.hk

2016-04-18

We report a metasurface for focusing reflected ultrasonic waves over a wide frequency band of 0.45–0.55 MHz. The broadband focusing effect of the reflective metasurface is studied numerically and then confirmed experimentally using near-field scanning techniques. The focusing mechanism can be attributed to the hyperboloidal reflection phase profile imposed by different depths of concentric grooves on the metasurface. In particular, the focal lengths of the reflective metasurface are extracted from simulations and experiments, and both exhibit good linear dependence on frequency over the considered frequency band. The proposed broadband reflective metasurface with tunable focal length has potential applications in the broadmore » field of ultrasonics, such as ultrasonic tomographic imaging, high intensity focused ultrasound treatment, etc.« less

FOCUSING OF HIGH POWER ULTRASOUND BEAMS AND LIMITING VALUES OF SHOCK WAVE PARAMETERS

PubMed Central

Bessonova, O.V.; Khokhlova, V.A.; Bailey, M.R.; Canney, M.S.; Crum, L.A.

2009-01-01

In this work, the influence of nonlinear and diffraction effects on amplification factors of focused ultrasound systems is investigated. The limiting values of acoustic field parameters obtained by focusing of high power ultrasound are studied. The Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation was used for the numerical modeling. Solutions for the nonlinear acoustic field were obtained at output levels corresponding to both pre- and post- shock formation conditions in the focal area of the beam in a weakly dissipative medium. Numerical solutions were compared with experimental data as well as with known analytic predictions. PMID:20161349

FOCUSING OF HIGH POWER ULTRASOUND BEAMS AND LIMITING VALUES OF SHOCK WAVE PARAMETERS.

PubMed

Bessonova, O V; Khokhlova, V A; Bailey, M R; Canney, M S; Crum, L A

2009-07-21

In this work, the influence of nonlinear and diffraction effects on amplification factors of focused ultrasound systems is investigated. The limiting values of acoustic field parameters obtained by focusing of high power ultrasound are studied. The Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation was used for the numerical modeling. Solutions for the nonlinear acoustic field were obtained at output levels corresponding to both pre- and post- shock formation conditions in the focal area of the beam in a weakly dissipative medium. Numerical solutions were compared with experimental data as well as with known analytic predictions.

Focusing of high power ultrasound beams and limiting values of shock wave parameters

NASA Astrophysics Data System (ADS)

Bessonova, O. V.; Khokhlova, V. A.; Bailey, M. R.; Canney, M. S.; Crum, L. A.

2009-10-01

In this work, the influence of nonlinear and diffraction effects on amplification factors of focused ultrasound systems is investigated. The limiting values of acoustic field parameters obtained by focusing of high power ultrasound are studied. The Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation was used for the numerical modeling. Solutions for the nonlinear acoustic field were obtained at output levels corresponding to both pre- and post-shock formation conditions in the focal area of the beam in a weakly dissipative medium. Numerical solutions were compared with experimental data as well as with known analytic predictions.

On radiation forces acting on a transparent nanoparticle in the field of a focused laser beam

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

Afanas'ev, A A; Rubinov, A N; Gaida, L S

2015-10-31

Radiation forces acting on a transparent spherical nanoparticle in the field of a focused Gaussian laser beam are studied theoretically in the Rayleigh scattering regime. Expressions are derived for the scattering force and Cartesian components of the gradient force. The resultant force acting on a nanoparticle located in the centre of a laser beam is found. The parameters of the focused beam and optical properties of the nanoparticle for which the longitudinal component of the gradient force exceeds the scattering force are determined. Characteristics of the transverse gradient force are discussed. (nanophotonics)

Is it new? Personal and contextual influences on perceptions of novelty and creativity.

PubMed

Zhou, Jing; Wang, Xiaoye May; Song, Lynda Jiwen; Wu, Junfeng

2017-02-01

Novelty recognition is the crucial starting point for extracting value from the ideas generated by others. In this paper we develop an associative evaluation account for how personal and contextual factors motivate individuals to perceive novelty and creativity. We report 4 studies that systematically tested hypotheses developed from this perspective. Study 1 (a laboratory experiment) showed that perceivers' regulatory focus, as an experimentally induced state, affected novelty perception. Study 2 (a field study) found that perceivers' promotion focus and prevention focus, measured as chronic traits, each interacted with normative level of novelty and creativity: perceivers who scored higher on promotion focus perceived more novelty (or creativity) in novel (or creative) targets than those who scored lower, whereas perceivers who scored higher on prevention focus perceived less novelty (or creativity) in novel (or creative) targets than those who scored lower. Study 3 (a field study) showed that organizational culture affected the perception of novelty and creativity. Study 4 (a laboratory experiment) found perceiver-by-idea-by-context 3-way interaction effects: for perceivers with prevention focus, the positive relation between normative level of novelty and novelty ratings was weakened in the loss-framing condition versus the gain-framing condition. We discuss implications of the findings for future research and management practice. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Application of optical interferometry in focused acoustic field measurement

NASA Astrophysics Data System (ADS)

Wang, Yuebing; Sun, Min; Cao, Yonggang; Zhu, Jiang

2018-07-01

Optical interferometry has been successfully applied in measuring acoustic pressures in plane-wave fields and spherical-wave fields. In this paper, the "effective" refractive index for focused acoustic fields was developed, through numerical simulation and experiments, the feasibility of the optical method in measuring acoustic fields of focused transducers was proved. Compared with the results from a membrane hydrophone, it was concluded that the optical method has good spatial resolution and is suitable for detecting focused fields with fluctuant distributions. The influences of a few factors (the generated lamb wave, laser beam directivity, etc.) were analyzed, and corresponding suggestions were proposed for effective application of this technology.

Supervisor Attachment, Supervisory Working Alliance, and Affect in Social Work Field Instruction

ERIC Educational Resources Information Center

Bennett, Susanne; Mohr, Jonathan; Deal, Kathleen Holtz; Hwang, Jeongha

2013-01-01

Objective: This study focused on interrelationships among supervisor attachment, supervisory working alliance, and supervision-related affect, plus the moderating effect of a field instructor training. Method: The researchers employed a pretest-posttest follow-up design of 100 randomly assigned field instructors and 64 students in two…

The significance of field work in monographic studies

USDA-ARS?s Scientific Manuscript database

The focus of this paper is to document the clear and obvious advantages of field work for monographic studies. These advantages include: 1) ability to understand published distributions better and greatly expand these data, 2) access to taxonomic data obscured on herbarium sheets (as colors, odors, ...

FOREWORD: Focus on Materials Analysis and Processing in Magnetic Fields Focus on Materials Analysis and Processing in Magnetic Fields

NASA Astrophysics Data System (ADS)

Sakka, Yoshio; Hirota, Noriyuki; Horii, Shigeru; Ando, Tsutomu

2009-03-01

Recently, interest in the applications of feeble (diamagnetic and paramagnetic) magnetic materials has grown, whereas the popularity of ferromagnetic materials remains steady and high. This trend is due to the progress of superconducting magnet technology, particularly liquid-helium-free superconducting magnets that can generate magnetic fields of 10 T and higher. As the magnetic energy is proportional to the square of the applied magnetic field, the magnetic energy of such 10 T magnets is in excess of 10 000 times that of conventional 0.1 T permanent magnets. Consequently, many interesting phenomena have been observed over the last decade, such as the Moses effect, magnetic levitation and the alignment of feeble magnetic materials. Researchers in this area are widely spread around the world, but their number in Japan is relatively high, which might explain the success of magnetic field science and technology in Japan. Processing in magnetic fields is a rapidly expanding research area with a wide range of promising applications in materials science. The 3rd International Workshop on Materials Analysis and Processing in Magnetic Fields (MAP3), which was held on 14-16 May 2008 at the University of Tokyo, Japan, focused on various topics including magnetic field effects on chemical, physical, biological, electrochemical, thermodynamic and hydrodynamic phenomena; magnetic field effects on the crystal growth and processing of materials; diamagnetic levitation, the magneto-Archimedes effect, spin chemistry, magnetic orientation, control of structure by magnetic fields, magnetic separation and purification, magnetic-field-induced phase transitions, properties of materials in high magnetic fields, the development of NMR and MRI, medical applications of magnetic fields, novel magnetic phenomena, physical property measurement by magnetic fields, and the generation of high magnetic fields. This focus issue compiles 13 key papers selected from the proceedings of MAP3. Other papers of the proceedings are published in Journal of Physics: Conference Series. Tournier and Beaugnon review experimental texturing in metallic melts by cooling in magnetic fields, which is modeled in detail in a study by Tournier. Wang et al provide further experimental results on the solidification of Mn-90.4 wt % Sb alloy in magnetic fields. The orientations of grains and particles induced by magnetic fields is reported by Horii et al (rare-earth-doped cuprates), Tanaka et al (barium-bismuth titanate ceramics), Liu and Schwartz (Bi2Sr2CaCu2Ox/AgMg wires) and Tsuda and Sakka (carbon nanotubes). Gielen et al present a model of how to quantify a molecular alignment using magnetic birefringence, and Ando et al simulate the movement of feeble particles in magnetic fields. Hirota et al report the experimental control of the lattice constant in a triangular lattice of feeble magnetic particles. The size separation of diamagnetic particles by magnetic fields is experimentally studied by Tarn et al and theoretically studied by Fukui et al. A setup measuring x-ray diffraction patterns in magnetic fields up to 5 T and temperatures above 200 oC has been developed by Mitsui et al. We hope that this focus issue will help readers to understand several aspects of materials analysis and processing in magnetic fields at the frontier of the science.

Full acoustic and thermal characterization of HIFU field in the presence of a ribcage model

NASA Astrophysics Data System (ADS)

Cao, Rui; Le, Nhan; Nabi, Ghulam; Huang, Zhihong

2017-03-01

In the treatment of abdominal organs using high intensity focused ultrasound (HIFU), the patient's ribs are in the pathway of the HIFU beams which could result in acoustic distortion, occasional skin burns and insufficient energy delivered to the target organs. To provide full characterization of HIFU field with the influence of ribcage, the ribcage phantom reconstructed from a patient's CT images was created by tissue mimicking materials and its effect on acoustic field was characterized. The effect of the ribcage on acoustic field has been provided in acoustic pressure distribution, acoustic power and focal temperature. Measurement result shows focus splitting with one main focus and two secondary intensity maxima. With the presence of ribcage phantom, the acoustic pressure was reduced by 48.3% and another two peak values were observed near the main focus, reduced by 65.0% and 71.7% respectively. The acoustic power was decreased by 47.5% to 52.5%. With these characterization results, the form of the focus, the acoustic power, acoustic pressure and temperature rise are provided before the transcostal HIFU treatment, which are significant to determine the energy delivery dose. In conclusion, this ribcage model and characterization technique will be useful for the further study in the abdominal HIFU treatment.

Utilizing Light-field Imaging Technology in Neurosurgery.

PubMed

Chen, Brian R; Buchanan, Ian A; Kellis, Spencer; Kramer, Daniel; Ohiorhenuan, Ifije; Blumenfeld, Zack; Grisafe Ii, Dominic J; Barbaro, Michael F; Gogia, Angad S; Lu, James Y; Chen, Beverly B; Lee, Brian

2018-04-10

Traditional still cameras can only focus on a single plane for each image while rendering everything outside of that plane out of focus. However, new light-field imaging technology makes it possible to adjust the focus plane after an image has already been captured. This technology allows the viewer to interactively explore an image with objects and anatomy at varying depths and clearly focus on any feature of interest by selecting that location during post-capture viewing. These images with adjustable focus can serve as valuable educational tools for neurosurgical residents. We explore the utility of light-field cameras and review their strengths and limitations compared to other conventional types of imaging. The strength of light-field images is the adjustable focus, as opposed to the fixed-focus of traditional photography and video. A light-field image also is interactive by nature, as it requires the viewer to select the plane of focus and helps with visualizing the three-dimensional anatomy of an image. Limitations include the relatively low resolution of light-field images compared to traditional photography and video. Although light-field imaging is still in its infancy, there are several potential uses for the technology to complement traditional still photography and videography in neurosurgical education.

Utilizing Light-field Imaging Technology in Neurosurgery

PubMed Central

Chen, Brian R; Kellis, Spencer; Kramer, Daniel; Ohiorhenuan, Ifije; Blumenfeld, Zack; Grisafe II, Dominic J; Barbaro, Michael F; Gogia, Angad S; Lu, James Y; Chen, Beverly B; Lee, Brian

2018-01-01

Traditional still cameras can only focus on a single plane for each image while rendering everything outside of that plane out of focus. However, new light-field imaging technology makes it possible to adjust the focus plane after an image has already been captured. This technology allows the viewer to interactively explore an image with objects and anatomy at varying depths and clearly focus on any feature of interest by selecting that location during post-capture viewing. These images with adjustable focus can serve as valuable educational tools for neurosurgical residents. We explore the utility of light-field cameras and review their strengths and limitations compared to other conventional types of imaging. The strength of light-field images is the adjustable focus, as opposed to the fixed-focus of traditional photography and video. A light-field image also is interactive by nature, as it requires the viewer to select the plane of focus and helps with visualizing the three-dimensional anatomy of an image. Limitations include the relatively low resolution of light-field images compared to traditional photography and video. Although light-field imaging is still in its infancy, there are several potential uses for the technology to complement traditional still photography and videography in neurosurgical education. PMID:29888163

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

ERIC Educational Resources Information Center

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

2013-01-01

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

James D. Finn's Contribution to the Development of a Process View of Educational Technology.

ERIC Educational Resources Information Center

Januszewski, Alan

This study focuses on the thoughts and activities of James D. Finn and examines the influence that these thoughts and activities had on later events and outcomes in the field of educational technology. Finn aimed to upgrade the status of audiovisual education to a professional field of study and endeavored to change the name of the field to…

Facilitating Middle Level Pre-Service Teachers' Literacy Integration in Early Field Experiences

ERIC Educational Resources Information Center

Leckie, Alisa; Wall, Amanda

2016-01-01

This study explored how pre-service teachers integrated literacy in middle level social studies. This study was conducted in the context of the Common Core State Standards (CCSS) and their focus on disciplinary literacy, the Council for the Accreditation of Educator Preparation (CAEP) Standards and their focus on rich clinical experiences, and…

Study of Bacterial Response to Antibiotics in Low Magnetic Fields

NASA Astrophysics Data System (ADS)

Abdul-Moqueet, Mohammad; Albalawi, Abdullah; Masood, Samina

Effect of low magnetic fields on bacterial growth has been well established. Current study shows how different magnetic fields effect the bacterial response to antibiotics shows that the bacterial infections treatment and disease cure is changed in the presence of weak fields. This study has focused on understanding how different types of low magnetic fields change the response the bacterium to antibiotics in a liquid medium. This low magnetic field coupled with the introduction of antibiotics to the growth medium shows a drop in the growth curve. The most significant effect of low magnetic fields was seen with the uniform electromagnetic field as compared to the similar strength of constant static magnetic field produced by a bar magnets.

Independence and Interdependence: An Analysis of Pre-Service Candidates' Use of Focused Assignments on an Electronic Discussion Forum during the Initial Field Experience

ERIC Educational Resources Information Center

Fisch, Audrey A.; Bennett, Deborah J.

2011-01-01

This article describes a case study using an electronic learning platform for creating an interactive learning community through asynchronous discussion to enhance the initial field experience of secondary math and English teacher candidates enrolled in Field Experience. We identified three problems with the field experience course--lack of…

Peace Studies, the Gulf War, and Peace.

ERIC Educational Resources Information Center

Stephenson, Carolyn M.

1991-01-01

Peace studies, as an academic discipline, dates back to the 1950s, when the field was characterized primarily by research. The 1970s brought a focus on undergraduate education. In the 1980s, a third wave brought the field into a prominence that allows it to challenge the Gulf War. (SLD)

Achievement of needle-like focus by engineering radial-variant vector fields.

PubMed

Gu, Bing; Wu, Jia-Lu; Pan, Yang; Cui, Yiping

2013-12-16

We present and demonstrate a novel method for engineering the radial-variant polarization on the incident field to achieve a needle of transversally polarized field without any pupil filters. We generate a new kind of localized linearly-polarized vector fields with distributions of states of polarization (SoPs) describing by the radius to the power p and explore its tight focusing, nonparaxial focusing, and paraxial focusing properties. By tuning the power p, we obtain the needle-like focal field with hybrid SoPs and give the formula for describing the length of the needle. Experimentally, we systematically investigate both the intensity distributions and the polarization evolution of the optical needle by paraxial focusing the generated vector field. Such an optical needle, which enhances the light-matter interaction, has intriguing applications in optical microma-chining and nonlinear optics.

Investigation of shape, position, and permeability of shielding material in quadruple butterfly coil for focused transcranial magnetic stimulation

NASA Astrophysics Data System (ADS)

Rastogi, Priyam; Zhang, Bowen; Tang, Yalun; Lee, Erik G.; Hadimani, Ravi L.; Jiles, David C.

2018-05-01

Transcranial magnetic stimulation has been gaining popularity in the therapy for several neurological disorders. A time-varying magnetic field is used to generate electric field in the brain. As the development of TMS methods takes place, emphasis on the coil design increases in order to improve focal stimulation. Ideally reduction of stimulation of neighboring regions of the target area is desired. This study, focused on the improvement of the focality of the Quadruple Butterfly Coil (QBC) with supplemental use of different passive shields. Parameters such as shape, position and permeability of the shields have been explored to improve the focus of stimulation. Results have been obtained with the help of computer modelling of a MRI derived heterogeneous head model over the vertex position and the dorsolateral prefrontal cortex position using a finite element tool. Variables such as maximum electric field induced on the grey matter and scalp, volume and area of stimulation above half of the maximum value of electric field on the grey matter, and ratio of the maximum electric field in the brain versus the scalp have been investigated.

Magnetic Assisted Colloidal Pattern Formation

NASA Astrophysics Data System (ADS)

Yang, Ye

Pattern formation is a mysterious phenomenon occurring at all scales in nature. The beauty of the resulting structures and myriad of resulting properties occurring in naturally forming patterns have attracted great interest from scientists and engineers. One of the most convenient experimental models for studying pattern formation are colloidal particle suspensions, which can be used both to explore condensed matter phenomena and as a powerful fabrication technique for forming advanced materials. In my thesis, I have focused on the study of colloidal patterns, which can be conveniently tracked in an optical microscope yet can also be thermally equilibrated on experimentally relevant time scales, allowing for ground states and transitions between them to be studied with optical tracking algorithms. In particular, I have focused on systems that spontaneously organize due to particle-surface and particle-particle interactions, paying close attention to systems that can be dynamically adjusted with an externally applied magnetic or acoustic field. In the early stages of my doctoral studies, I developed a magnetic field manipulation technique to quantify the adhesion force between particles and surfaces. This manipulation technique is based on the magnetic dipolar interactions between colloidal particles and their "image dipoles" that appear within planar substrate. Since the particles interact with their own images, this system enables massively parallel surface force measurements (>100 measurements) in a single experiment, and allows statistical properties of particle-surface adhesion energies to be extracted as a function of loading rate. With this approach, I was able to probe sub-picoNewton surface interactions between colloidal particles and several substrates at the lowest force loading rates ever achieved. In the later stages of my doctoral studies, I focused on studying patterns formed from particle-particle interaction, which serve as an experimental model of phase transitions in condensed matter systems that can be tracked with single particle resolution. Compared with other research on colloidal crystal formation, my research has focused on multi-component colloidal systems of magnetic and non-magnetic colloids immersed in a ferrofluid. Initially, I studied the types of patterns that form as a function of the concentrations of the different particles and ferrofluid, and I discovered a wide variety of chains, rings and crystals forming in bi-component and tri-component systems. Based on these results, I narrowed my focus to one specific crystal structure (checkerboard lattice) as a model of phase transformations in alloy. Liquid/solid phase transitions were studied by slowly adjusting the magnetic field strength, which serves to control particle-particle interactions in a manner similar to controlling the physical temperature of the fluid. These studies were used to determine the optimal conditions for forming large single crystal structures, and paved the way for my later work on solid/solid phase transitions when the angle of the external field was shifted away from the normal direction. The magnetostriction coefficient of these crystals was measured in low tilt angle of the applied field. At high tilt angles, I observed a variety of martensitic transformations, which followed different pathways depending on the crystal direction relative to the in-plane field. In the last part of my doctoral studies, I investigated colloidal patterns formed in a superimposed acoustic and magnetic field. In this approach, the magnetic field mimics "temperature", while the acoustic field mimics "pressure". The ability to simultaneously tune both temperature and pressure allows for more efficient exploration of phase space. With this technique I demonstrated a large class of particle structures ranging from discrete molecule-like clusters to well ordered crystal phases. Additionally, I demonstrated a crosslinking strategy based on photoacids, which stabilized the structures after the external field was removed. This approach has potential applications in the fabrication of advanced materials. My thesis is arranged as follows. In Chapter 1, I present a brief background of general pattern formation and why I chose to investigate patterns formed in colloidal systems. I also provide a brief review of field-assisted manipulation techniques in order to motivate why I selected magnetic and acoustic field to study colloidal patterns. In chapter 2, I present the theoretical background of magnetic manipulation, which is the main technique used in my research. In this chapter, I will introduce the basic knowledge on magnetic materials and theories behind magnetic manipulation. The underlining thermodynamic mechanisms and theoretical/computational approaches in colloidal pattern formation are also briefly reviewed. In Chapter 3, I focus on using these concepts to study adhesion forces between particle and surfaces. In Chapter 4, I focus on exploring the ground states of colloidal patterns formed from the anti-ferromagnetic interactions of mixtures of particles, as a function of the particle volume fractions. In Chapter 5, I discuss my research on phase transformations of the well-ordered checkerboard phase formed from the equimolar mixture of magnetic and non-magnetic beads in ferrofluid, and I focus mainly on phase transformations in a slowly varying magnetic field. In Chapter 6, I discuss my work on the superimposed magnetic and acoustic field to study patterns formed from monocomponent colloidal suspensions under vertical confinement. Finally, I conclude my thesis in Chapter 7 and discuss future directions and open questions that can be explored in magnetic field directed self-organization in colloidal systems.

Light focusing using epsilon-near-zero metamaterials

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

Zhu, Weiren, E-mail: weiren.zhu@monash.edu; Premaratne, Malin; Si, Li-Ming, E-mail: lms@bit.edu.cn

2013-11-15

We present a strategy of focusing light using epsilon-near-zero metamaterials with embedded dielectric cylinder. The focusing mechanism is analytically investigated, and its accuracy is substantiated by rigorous full-wave simulations. It is found that the focusing intensity is highly depend on the embedded medium and its size, and the magnetic field amplitude of the focused beam itself can reach as high as 98.2 times the incident field. Owing to its versatility, the proposed light focusing system is sure to find applications in fields such as bio-sensing and in nonlinear optics.

Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

DOE PAGES

Dorf, Mikhail A.; Davidson, Ronald C.; Kaganovich, Igor D.; ...

2012-05-31

In this study, the design of ion drivers for warm dense matter and high energy density physics applications and heavy ion fusion involves transverse focusing and longitudinal compression of intense ion beams to a small spot size on the target. To facilitate the process, the compression occurs in a long drift section filled with a dense background plasma, which neutralizes the intense beam self-fields. Typically, the ion bunch charge is better neutralized than its current, and as a result a net self-pinching (magnetic) force is produced. The self-pinching effect is of particular practical importance, and is used in various ionmore » driver designs in order to control the transverse beam envelope. In the present work we demonstrate that this radial self-focusing force can be significantly enhanced if a weak (B~100 G) solenoidal magnetic field is applied inside the neutralized drift section, thus allowing for substantially improved transport. It is shown that in contrast to magnetic self-pinching, the enhanced collective self-focusing has a radial electric field component and occurs as a result of the overcompensation of the beam charge by plasmaelectrons, whereas the beam current becomes well-neutralized. As the beam leaves the neutralizing drift section, additional transverse focusing can be applied. For instance, in the neutralized drift compression experiments (NDCX) a strong (several Tesla) final focus solenoid is used for this purpose. In the present analysis we propose that the tight final focus in the NDCX experiments may possibly be achieved by using a much weaker (few hundred Gauss) magnetic lens, provided the ion beam carries an equal amount of co-moving neutralizing electrons from the preceding drift section into the lens. In this case the enhanced focusing is provided by the collective electrondynamics strongly affected by a weak applied magnetic field.« less

Interactions between sediment storage and bed material transport: A field and flume study

Treesearch

Bonnie J. Smith; Thomas E. Lisle; Diane G. Sutherland; Sue Hilton; Harvey M. Kelsey; Eileen M. Cashman

2002-01-01

Significant channel aggradation events have occurred in numerous coastal northern California watersheds over the past 50 years, leaving lasting impacts on stream channel morphology and habitats. Our study focuses on sediment movement and channel morphology following large aggradation events and specifically focuses on the relationship between volume of stored sediment...

When Risk Becomes Invisible in the Everyday Life of Day Care

ERIC Educational Resources Information Center

Villumsen, Anne Marie; Kristensen, Ole Steen

2016-01-01

Both the identification of children at risk in day care and multidisciplinary collaboration with other professions have a political focus. This study was designed as an organizational field study and attempts to establish a coherent practice of multidisciplinary collaboration between day care and social services. This article focuses on the…

Design Criteria for Learning and Teaching Genetics

ERIC Educational Resources Information Center

Knippels, Marie-Christine P. J.; Waarlo, Arend Jan; Boersma, Kerst Th.

2005-01-01

While learning and teaching difficulties in genetics have been abundantly explored and described, there has been less focus on the development and field-testing of strategies to address them. To inform the design of such a strategy a review study, focus group interviews with teachers, a case study of a traditional series of genetics lessons,…

The Community College Baccalaureate Movement: Cutting-Edge Dissertation Research

ERIC Educational Resources Information Center

Hrabak, Michael R.

2009-01-01

In this review of dissertations, the researcher presents summaries of 10 of the most recent and cutting-edge dissertations focusing on the ever-growing and complex field of the community college baccalaureate movement. These studies focus on the gamut of specific legislation, case studies of particular programs and schools, financing of such…

Far-field self-focusing and -defocusing radiation behaviors of the electroluminescent light sources due to negative refraction.

PubMed

Yin, Yu-Feng; Lin, Yen-Chen; Tsai, Tsung-Han; Shen, Yi-Chun; Huang, Jianjang

2013-01-15

In recent years, researchers have demonstrated negative refraction theoretically and experimentally by pumping optical power into photonic crystal (PhC) or waveguide structures. The concept of negative refraction can be used to create a perfect lens that focuses an object smaller than the wavelength. By inserting two-dimensional PhCs into the peripheral of a semiconductor light emitting structure, this study presents an electroluminescent device with negative refraction in the visible wavelength range. This approach produces polarization dependent collimation behavior in far-field radiation patterns. The modal dispersion of negative refraction results in strong group velocity modulation, and self-focusing and -defocusing behaviors are apparent from light extraction. This study further verifies experimental results by using theoretic calculations based on equifrequency contours.

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.

On discrete field theory properties of the dimer and Ising models and their conformal field theory limits

NASA Astrophysics Data System (ADS)

Kriz, Igor; Loebl, Martin; Somberg, Petr

2013-05-01

We study various mathematical aspects of discrete models on graphs, specifically the Dimer and the Ising models. We focus on proving gluing formulas for individual summands of the partition function. We also obtain partial results regarding conjectured limits realized by fermions in rational conformal field theories.

The Impact of an Inquiry-Based Geoscience Field Course on Pre-Service Teachers

ERIC Educational Resources Information Center

Nugent, Gwen; Toland, Michael D.; Levy, Richard; Kunz, Gina; Harwood, David; Green, Denise; Kitts, Kathy

2012-01-01

The purpose of this quasi-experimental study was to determine the effects of a field-based, inquiry-focused course on pre-service teachers' geoscience content knowledge, attitude toward science, confidence in teaching science, and inquiry understanding and skills. The field-based course was designed to provide students with opportunities to…

When does self-sacrificial leadership motivate prosocial behavior? It depends on followers' prevention focus.

PubMed

De Cremer, David; Mayer, David M; van Dijke, Marius; Bardes, Mary; Schouten, Barbara C

2009-07-01

In the present set of studies, the authors examine the idea that self-sacrificial leadership motivates follower prosocial behavior, particularly among followers with a prevention focus. Drawing on the self-sacrificial leadership literature and regulatory focus theory, the authors provide results from 4 studies (1 laboratory and 3 field studies) that support the research hypothesis. Specifically, the relationship between self-sacrificial leadership and prosocial behavior (i.e., cooperation, organizational citizenship behavior) is stronger among followers who are high in prevention focus. Implications for the importance of taking a follower-centered approach to leadership are discussed.

This Isn't Business, It's Personal: Personal Narratives in the Field of Composition Studies

ERIC Educational Resources Information Center

Golar, Norman

2010-01-01

I focus on three critical autobiographies in the field of composition studies: Mike Rose's "Lives on the Boundary: A Moving Account of the Struggles and Achievements of America's Educationally Underprepared," Keith Gilyard's "Voices of the Self: A Study of Language Competence," and Victor Villanueva, Jr.'s "Bootstraps: From an American Academic of…

Occupational and Qualification Structures in the Field of Environmental Protection in the Metal and Chemical Industries--Study on the Federal Republic of Germany.

ERIC Educational Resources Information Center

Nitschke, Christoph; And Others

A study focused on new occupational and qualification structures in the field of environmental protection in the metal and chemical industries in the Federal Republic of Germany. A total of 22 interviews were conducted with representatives of 11 firms. The public debate on occupational requirements in the field of environmental protection and on…

Primordial perturbations in multi-scalar inflation

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

Abedi, Habib; Abbassi, Amir M., E-mail: h.abedi@ut.ac.ir, E-mail: amabasi@khayam.ut.ac.ir

2017-07-01

Multiple field models of inflation exhibit new features than single field models. In this work, we study the hierarchy of parameters based on Hubble expansion rate in curved field space and derive the system of flow equations that describe their evolutions. Then we focus on obtaining derivatives of number of e-folds with respect to scalar fields during inflation and at hypersurface of the end of inflation.

Optical transverse spin coupling through a plasmonic nanoparticle for particle-identification and field-mapping.

PubMed

Yang, A P; Du, L P; Meng, F F; Yuan, X C

2018-05-17

Electromagnetic fields at near-field exhibit distinctive properties with respect to their free-space counterparts. In particular, an optical transverse spin appearing in a confined electromagnetic field provides the foundation for many intriguing physical effects and applications. We present a transverse spin coupling configuration where plasmonic nanoparticles are employed to couple the transverse spin in a focused beam to that of a surface plasmon polariton. The plasmonic resonance of nanoparticles on a metal film plays a significant role in transverse spin coupling. We demonstrate in experiments that Ag and Au nanoparticles yield distinct imaging patterns when scanned over a focused field, because of their different plasmonic responses to the transverse and longitudinal electric fields. Such resonance-dependent spin-coupling enables the identification of nanoparticles using a focused field, as well as electric field mapping of a specific field component of a focused beam using a plasmonic nanoparticle. These interesting findings regarding the transverse spin coupling with a plasmonic nanoparticle may find valuable applications in near-field and nano-optics.

Vector optical fields with bipolar symmetry of linear polarization.

PubMed

Pan, Yue; Li, Yongnan; Li, Si-Min; Ren, Zhi-Cheng; Si, Yu; Tu, Chenghou; Wang, Hui-Tian

2013-09-15

We focus on a new kind of vector optical field with bipolar symmetry of linear polarization instead of cylindrical and elliptical symmetries, enriching members of family of vector optical fields. We design theoretically and generate experimentally the demanded vector optical fields and then explore some novel tightly focusing properties. The geometric configurations of states of polarization provide additional degrees of freedom assisting in engineering the field distribution at the focus to the specific applications such as lithography, optical trapping, and material processing.

A computational study for investigating acoustic streaming and tissue heating during high intensity focused ultrasound through blood vessel with an obstacle

NASA Astrophysics Data System (ADS)

Parvin, Salma; Sultana, Aysha

2017-06-01

The influence of High Intensity Focused Ultrasound (HIFU) on the obstacle through blood vessel is studied numerically. A three-dimensional acoustics-thermal-fluid coupling model is employed to compute the temperature field around the obstacle through blood vessel. The model construction is based on the linear Westervelt and conjugate heat transfer equations for the obstacle through blood vessel. The system of equations is solved using Finite Element Method (FEM). We found from this three-dimensional numerical study that the rate of heat transfer is increasing from the obstacle and both the convective cooling and acoustic streaming can considerably change the temperature field.

Three-dimensional investigations of the threading regime in a microfluidic flow-focusing channel

NASA Astrophysics Data System (ADS)

Gowda, Krishne; Brouzet, Christophe; Lefranc, Thibault; Soderberg, L. Daniel; Lundell, Fredrik

2017-11-01

We study the flow dynamics of the threading regime in a microfluidic flow-focusing channel through 3D numerical simulations and experiments. Making strong filaments from cellulose nano-fibrils (CNF) could potentially steer to new high-performance bio-based composites competing with conventional glass fibre composites. CNF filaments can be obtained through hydrodynamic alignment of dispersed CNF by using the concept of flow-focusing. The aligned structure is locked by diffusion of ions resulting in a dispersion-gel transition. Flow-focusing typically refers to a microfluidic channel system where the core fluid is focused by the two sheath fluids, thereby creating an extensional flow at the intersection. In this study, threading regime corresponds to an extensional flow field generated by the water sheath fluid stretching the dispersed CNF core fluid and leading to formation of long threads. The experimental measurements are performed using optical coherence tomography (OCT) and 3D numerical simulations with OpenFOAM. The prime focus is laid on the 3D characteristics of thread formation such as wetting length of core fluid, shape, aspect ratio of the thread and velocity flow-field in the microfluidic channel.

Teachers Working in the Field of Environmental Education: Musings of a Practitioner

ERIC Educational Resources Information Center

Neves, Eloiza Dias

2005-01-01

Over the last century, much was researched in the field of Education, be its educational policies or more effective learning strategies. It is only recently that studies have begun to focus on the teachers. This article describes an investigation about how the knowledge of teachers working in the field of Environmental Education is formed,…

Factors That Influence Student's Satisfaction in an Environmental Field Day Experience

ERIC Educational Resources Information Center

Wang, Hui-Hui; Carlson, Stephan P.

2011-01-01

A field trip is a common strategy used by educators to bring out-of-school learning experience into schools. Many research studies suggest a field trip will not only bring an individual close to the real-world, but may also increase an individual's environmental knowledge and responsible behaviors. Program evaluations usually focus on the…

Skills Utilisation at Work, the Quality of the Study Programme and Fields of Study

ERIC Educational Resources Information Center

Støren, Liv Anne; Arnesen, Clara Åse

2016-01-01

This paper examines the factors that may have impact on the extent to which the knowledge and skills of master's degree graduates in Norway are utilised at work, three years after graduation. The focus is on the impact of the quality of the study programme as well as the graduates' fields of study, when also taking into account other factors…

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.

Emerging directions in the study of the ecology and evolution of plant-animal mutualistic networks: a review.

PubMed

Gu, Hao; Goodale, Eben; Chen, Jin

2015-03-18

The study of mutualistic plant and animal networks is an emerging field of ecological research. We reviewed progress in this field over the past 30 years. While earlier studies mostly focused on network structure, stability, and biodiversity maintenance, recent studies have investigated the conservation implications of mutualistic networks, specifically the influence of invasive species and how networks respond to habitat loss. Current research has also focused on evolutionary questions including phylogenetic signal in networks, impact of networks on the coevolution of interacting partners, and network influences on the evolution of interacting species. We outline some directions for future research, particularly the evolution of specialization in mutualistic networks, and provide concrete recommendations for environmental managers.

Conductivity of molten sodium chloride in an arbitrarily weak dc electric field.

PubMed

Delhommelle, Jerome; Cummings, Peter T; Petravic, Janka

2005-09-15

We use nonequilibrium molecular-dynamics (NEMD) simulations to characterize the response of a fluid subjected to an electric field. We focus on the response for very weak fields. Fields accessible by conventional NEMD methods are typically of the order of 10(9) V m(-1), i.e., several orders of magnitude larger than those typically used in experiments. Using the transient time-correlation function, we show how NEMD simulations can be extended to study systems subjected to a realistic dc electric field. We then apply this approach to study the response of molten sodium chloride for a wide range of dc electric fields.

Techniques For Focusing In Zone Electrophoresis

NASA Technical Reports Server (NTRS)

Sharnez, Rizwan; Twitty, Garland E.; Sammons, David W.

1994-01-01

In two techniques for focusing in zone electrophoresis, force of applied electrical field in each charged particle balanced by restoring force of electro-osmosis. Two techniques: velocity-gradient focusing (VGF), suitable for rectangular electrophoresis chambers; and field-gradient focusing (FGF), suitable for step-shaped electrophoresis chambers.

Engineering of multi-segmented light tunnel and flattop focus with designed axial lengths and gaps

NASA Astrophysics Data System (ADS)

Yu, Yanzhong; Huang, Han; Zhou, Mianmian; Zhan, Qiwen

2018-01-01

Based on the radiation pattern from a sectional-uniform line source antenna, a three-dimensional (3D) focus engineering technique for the creation of multi-segmented light tunnel and flattop focus with designed axial lengths and gaps is proposed. Under a 4Pi focusing system, the fields radiated from sectional-uniform magnetic and electromagnetic current line source antennas are employed to generate multi-segmented optical tube and flattop focus, respectively. Numerical results demonstrate that the produced light tube and flattop focus remain homogeneous along the optical axis; and their lengths of the nth segment and the nth gap between consecutive segments can be easily adjusted and only depend on the sizes of the nth section and the nth blanking between adjacent sectional antennas. The optical tube is a pure azimuthally polarized field but for the flattop focus the longitudinal polarization is dominant on the optical axis. To obtain the required pupil plane illumination for constructing the above focal field with prescribed characteristics, the inverse problem of the antenna radiation field is solved. These peculiar focusing fields might find potential applications in multi-particle acceleration, multi-particle trapping and manipulation.

Health effects of electric and magnetic fields: Overview of research recommendations

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

Savitz, D.A.

We developed a series of articles concerning epidemiologic research on potential health effects of electric and magnetic fields. Our goal was to identify methodological issues that have arisen through past studies of cancer, reproduction, and neurobehavioral outcomes in order to suggest strategies to extend knowledge. Following an overview of relevant physics and engineering principles, cancer epidemiology of electric and magnetic fields is discussed separately with a focus on epidemiologic methods and cancer biology, respectively. Reproductive health studies, many of which focus on exposure from video display terminals are then summarized, followed by an evaluation of the limited literature on neurobehavioralmore » outcomes, including suicide and depression. Methodological issues in exposure assessment are discussed, focusing on the challenges in residential exposure assessment and interpretation of wire configuration codes. An overview offers recommendations for priorities across these topic areas, emphasizing the importance of resolving the question of wire codes and childhood cancer. Collectively, these articles provide an array of observations and suggestions regarding the epidemiologic literature, recognizing the potential benefits to science and public policy. 10 refs.« less

Acoustic characterization of high intensity focused ultrasound fields generated from a transmitter with a large aperture

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

Chen, Tao; Fan, Tingbo; Jiangsu Province Institute for Medical Equipment Testing, Nanjing 210012

Prediction and measurement of the acoustic field emitted from a high intensity focused ultrasound (HIFU) is essential for the accurate ultrasonic treatment. In this study, the acoustic field generated from a strongly focused HIFU transmitter was characterized by a combined experiment and simulation method. The spheroidal beam equation (SBE) was utilized to describe the nonlinear sound propagation. The curve of the source pressure amplitude versus voltage excitation was determined by fitting the measured ratio of the second harmonic to the fundamental component of the focal waveform to the simulation result; finally, the acoustic pressure field generated by the strongly focusedmore » HIFU transmitter was predicted by using the SBE model. A commercial fiber optic probe hydrophone was utilized to measure the acoustic pressure field generated from a 1.1 MHz HIFU transmitter with a large half aperture angle of 30°. The maximum measured peak-to-peak pressure was up to 72 MPa. The validity of this combined approach was confirmed by the comparison between the measured results and the calculated ones. The results indicate that the current approach might be useful to describe the HIFU field. The results also suggest that this method is not valid for low excitations owing to low sensitivity of the second harmonic.« less

Electron acceleration by a focused laser pulse in a static magnetic field

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

Huang Shihua; Wu Fengmin; Zhao Xianghao

2007-12-15

The model given by K. P. Singh [Phys. Rev. E 69, 056410 (2004)] for vacuum laser acceleration in a static magnetic field is revisited by including the effects of diffraction and the longitudinal electric field of a focused laser beam. Compared with a similar model without a static magnetic field, a simulation shows that electrons can gain much more net energy in this model even using the fifth-order corrected equations for the field of a focused laser beam. The acceleration mechanism and the acceleration efficiency are also investigated.

Effects of Field Instructor Training on Student Competencies and the Supervisory Alliance

ERIC Educational Resources Information Center

Deal, Kathleen Holtz; Bennett, Susanne; Mohr, Jonathan; Hwang, Jeongha

2011-01-01

Objectives: This study of a field instructor (FI) training model, offered at two universities, focused on the relationship between student competencies, the supervisory alliance, and students' attachment styles. Method: The study used a pretest-posttest follow-up design of 100 randomly assigned FIs (training group = 48; control group = 52) and 64…

Reforming Only Half: A Study of Practice-Based Teacher Education in Traditional Field Placements

ERIC Educational Resources Information Center

Francis, Anthony Tuf

2017-01-01

Practice-based teacher education is poised to improve teacher education by focusing on interns' enactment of complex teaching practices and helping them develop these professional skills. However, much of this work has yet to study the trajectory of learning between university training and field experiences. This article explores seven history and…

Stern-Gerlach dynamics with quantum propagators

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

Hsu, Bailey C.; Berrondo, Manuel; Van Huele, Jean-Francois S.

2011-01-15

We study the quantum dynamics of a nonrelativistic neutral particle with spin in inhomogeneous external magnetic fields. We first consider fields with one-dimensional inhomogeneities, both unphysical and physical, and construct the corresponding analytic propagators. We then consider fields with two-dimensional inhomogeneities and develop an appropriate numerical propagation method. We propagate initial states exhibiting different degrees of space localization and various initial spin configurations, including both pure and mixed spin states. We study the evolution of their spin densities and identify characteristic features of spin density dynamics, such as the spatial separation of spin components, and spin localization or accumulation. Wemore » compare our approach and our results with the coverage of the Stern-Gerlach effect in the literature, and we focus on nonstandard Stern-Gerlach outcomes, such as radial separation, spin focusing, spin oscillation, and spin flipping.« less

Apparatus and method for performing electrodynamic focusing on a microchip

DOEpatents

Ramsey, John Michael; Jacobson, Stephen C.

1999-01-01

A microchip device includes a focusing channel, in which an electric field strength established in the focusing channel is controlled relative to an electric field strength established in a material transport channel segment to spatially focus the material traversing the material transport channel segment.

Development of Professional Identity in Romanian Business Students

ERIC Educational Resources Information Center

Glaser-Segura, Daniel A.; Mudge, Suzanne; Bratianu, Constantin; Dumitru, Ionela

2010-01-01

Purpose: This study aims to focus on the role of learning activities on the development of Romanian students making the change from academia to the workplace, specifically focusing on the role of three learning activities: classroom teaching pedagogies ("in-vitro"); field experiences ("in-situ"); and self-development…

Women, Research Performance and Work Context

ERIC Educational Resources Information Center

Dever, Maryanne; Morrison, Zoe

2009-01-01

This article presents findings from a qualitative study focused on the conditions that support high research productivity in women. Interviewees were all active researchers and many were national or international leaders in their respective fields. While personal factors such as motivation, focus, and good scholarly habits were identified as…

Wave power focusing due to the Bragg resonance

NASA Astrophysics Data System (ADS)

Tao, Ai-feng; Yan, Jin; Wang, Yi; Zheng, Jin-hai; Fan, Jun; Qin, Chuan

2017-08-01

Wave energy has drawn much attention as an achievable way to exploit the renewable energy. At present, in order to enhance the wave energy extraction, most efforts have been concentrated on optimizing the wave energy convertor and the power take-off system mechanically and electrically. However, focusing the wave power in specific wave field could also be an alternative to improve the wave energy extraction. In this experimental study, the Bragg resonance effect is applied to focus the wave energy. Because the Bragg resonance effect of the rippled bottom largely amplifies the wave reflection, leading to a significant increase of wave focusing. Achieved with an energy conversion system consisting of a point absorber and a permanent magnet single phase linear motor, the wave energy extracted in the wave flume with and without Bragg resonance effect was measured and compared quantitatively in experiment. It shows that energy extraction by a point absorber from a standing wave field resulted from Bragg resonance effect can be remarkably increased compared with that from a propagating wave field (without Bragg resonance effect).

Development and relationship of monogenetic and polygenetic volcanic fields in time and space.

NASA Astrophysics Data System (ADS)

Germa, Aurelie; Connor, Chuck; Connor, Laura; Malservisi, Rocco

2013-04-01

The classification of volcanic systems, developed by G. P. L. Walker and colleagues, relates volcano morphology to magma transport and eruption processes. In general, distributed monogenetic volcanic fields are characterized by infrequent eruptions, low average output rate, and a low spatial intensity of the eruptive vents. In contrast, central-vent-dominated systems, such as stratovolcanoes, central volcanoes and lava shields are characterized by frequent eruptions, higher average flux rates, and higher spatial intensity of eruptive vents. However, it has been observed that a stratovolcano is often associated to parasitic monogenetic vents on its flanks, related to the central silicic systems, and surrounded by an apron of monogenetic edifices that are part of the volcanic field but independent from the principal central system. It appears from spatial distribution and time-volume relationships that surface area of monogenetic fields reflects the lateral extent of the magma source region and the lack of magma focusing mechanisms. In contrast, magma is focused through a unique conduit system for polygenetic volcanoes, provided by a thermally and mechanically favorable pathway toward the surface that is maintained by frequent and favorable stress conditions. We plan to relate surface observations of spatio-temporal location of eruptive vents and evolution of the field area through time to processes that control magma focusing during ascent and storage in the crust. We choose to study fields that range from dispersed to central-vent dominated, through transitional fields (central felsic system with peripheral field of monogenetic vents independent from the rhyolitic system). We investigate different well-studied volcanic fields in the Western US and Western Europe in order to assess influence of the geodynamic setting and tectonic stress on the spatial distribution of magmatism. In summary, incremental spatial intensity maps should reveal how fast a central conduit is created during the development of a volcanic field, and how this could influence the outbreak of dispersed monogenetic volcanoes that are not geochemically linked to the central system.

Finite-difference time-domain (FDTD) analysis on the interaction between a metal block and a radially polarized focused beam.

PubMed

Kitamura, Kyoko; Sakai, Kyosuke; Noda, Susumu

2011-07-18

Radially polarized focused beams have attracted a great deal of attention because of their unique properties characterized by the longitudinal field. Although this longitudinal field is strongly confined to the beam axis, the energy flow, i.e., the Poynting vector, has null intensity on the axis. Hence, the interaction of the focused beam and matter has thus far been unclear. We analyzed the interactions between the focused beam and a subwavelength metal block placed at the center of the focus using three-dimensional finite-difference time-domain (FDTD) calculation. We found that most of the Poynting energy propagates through to the far-field, and that a strong enhancement of the electric field appeared on the metal surface. This enhancement is attributed to the constructive interference of the symmetric electric field and the coupling to the surface plasmon mode.

Constructions of Following from a Relational Perspective: A Follower-Focused Study

ERIC Educational Resources Information Center

Morris, Rachael

2014-01-01

The followership field remains overshadowed by the leadership field, with traditional assumptions attached to the "follower" concept further undervaluing the importance of progressive understandings of leadership. This paper considers following as a relational process and provides illustrative extracts from empirical research. Future…

Simulations of stellar winds and planetary bodies: Magnetized obstacles in a super-Alfvénic flow with southward IMF

NASA Astrophysics Data System (ADS)

Vernisse, Y.; Riousset, J. A.; Motschmann, U.; Glassmeier, K.-H.

2018-03-01

This study addresses the issue of the electromagnetic interactions between a stellar wind and planetary magnetospheres with various dipole field strengths by means of hybrid simulations. Focus is placed on the configuration where the upstream plasma magnetic field is parallel to the planetary magnetic moment (also called "Southward-IMF" configuration), leading to anti-parallel magnetic fields in the dayside interaction region. Each type of plasma interaction is characterized by means of currents flowing in the interaction region. Reconnection triggered in the tail in such configuration is shown to affect significantly the structure of the magnetotail at early stages. On the dayside, only the magnetopause current is observable for moderate planetary dipole field amplitude, while both bow-shock and magnetotail currents are identifiable downtail from the terminator. Strong differences in term of temperature for ions are particularly noticeable in the magnetosheath and in the magnetotail, when the present results are compared with our previous study, which focused on "Northward-IMF" configuration.

Evolutionary ethnobiology and cultural evolution: opportunities for research and dialog.

PubMed

Santoro, Flávia Rosa; Nascimento, André Luiz Borba; Soldati, Gustavo Taboada; Ferreira Júnior, Washington Soares; Albuquerque, Ulysses Paulino

2018-01-09

The interest in theoretical frameworks that improve our understanding of social-ecological systems is growing within the field of ethnobiology. Several evolutionary questions may underlie the relationships between people and the natural resources that are investigated in this field. A new branch of research, known as evolutionary ethnobiology (EE), focuses on these questions and has recently been formally conceptualized. The field of cultural evolution (CE) has significantly contributed to the development of this new field, and it has introduced the Darwinian concepts of variation, competition, and heredity to studies that focus on the dynamics of local knowledge. In this article, we introduce CE as an important theoretical framework for evolutionary ethnobiological research. We present the basic concepts and assumptions of CE, along with the adjustments that are necessary for its application in EE. We discuss different ethnobiological studies in the context of this new framework and the new opportunities for research that exist in this area. We also propose a dialog that includes our findings in the context of cultural evolution.

Loosening the Ties That Bind: The Limitations of Youth-Centricity in Higher Education Admissions, Research, and Practice

ERIC Educational Resources Information Center

Iloh, Constance

2018-01-01

Much of what is known about college access, admissions, and student experiences is largely a result of studies and practices focused on "traditional-aged" college students. While these studies and efforts have provided substantial information to guide our field, they are inherently limited by their intentional and narrow focus on younger…

Women's decision to major in STEM fields

NASA Astrophysics Data System (ADS)

Conklin, Stephanie

This paper explores the lived experiences of high school female students who choose to enter into STEM fields, and describes the influencing factors which steered these women towards majors in computer science, engineering and biology. Utilizing phenomenological methodology, this study seeks to understand the essence of women's decisions to enter into STEM fields and further describe how the decision-making process varies for women in high female enrollment fields, like biology, as compared with low enrollment fields like, computer science and engineering. Using Bloom's 3-Stage Theory, this study analyzes how relationships, experiences and barriers influenced women towards, and possibly away, from STEM fields. An analysis of women's experiences highlight that support of family, sustained experience in a STEM program during high school as well as the presence of an influential teacher were all salient factors in steering women towards STEM fields. Participants explained that influential teacher worked individually with them, modified and extended assignments and also steered participants towards coursework and experiences. This study also identifies factors, like guidance counselors as well as personal challenges, which inhibited participant's path to STEM fields. Further, through analyzing all six participants' experiences, it is clear that a linear model, like Bloom's 3-Stage Model, with limited ability to include potential barriers inhibited the ability to capture the essence of each participant's decision-making process. Therefore, a revised model with no linear progression which allows for emerging factors, like personal challenges, has been proposed; this model focuses on how interest in STEM fields begins to develop and is honed and then mastered. This study also sought to identify key differences in the paths of female students pursuing different majors. The findings of this study suggest that the path to computer science and engineering is limited. Computer science majors faced few, if any, challenges, hoped to use computers as a tool to innovate and also participated in the same computer science program. For female engineering students, the essence of their experience focused on interaction at a young age with an expert in an engineering-related field as well as a strong desire to help solve world problems using engineering. These participants were able to articulate clearly future careers. In contrast, biology majors, faced more challenges and were undecided about their future career goals. These results suggest that a longitudinal study focused on women pursuing engineering and computer science fields is warranted; this will hopefully allow these findings to be substantiated and also for refinement of the revised theoretical model.

Thinking Globally, Planning Nationally and Acting Locally: Nested Organizational Fields and the Adoption of Environmental Practices

ERIC Educational Resources Information Center

Vasi, Ion Bogdan

2007-01-01

The study of the adoption of activities to protect the natural environment has tended to focus on the role of organizational fields. This article advances existing research by simultaneously examining conflicting processes that operate in nested organizational fields at local, national and supra-national levels. It examines the recent spread of an…

Steady-state protein focusing in carrier ampholyte based isoelectric focusing: Part I-Analytical solution.

PubMed

Shim, Jaesool; Yoo, Kisoo; Dutta, Prashanta

2017-03-01

The determination of an analytical solution to find the steady-state protein concentration distribution in IEF is very challenging due to the nonlinear coupling between mass and charge conservation equations. In this study, approximate analytical solutions are obtained for steady-state protein distribution in carrier ampholyte based IEF. Similar to the work of Svensson, the final concentration profile for proteins is assumed to be Gaussian, but appropriate expressions are presented in order to obtain the effective electric field and pH gradient in the focused protein band region. Analytical results are found from iterative solutions of a system of coupled algebraic equations using only several iterations for IEF separation of three plasma proteins: albumin, cardiac troponin I, and hemoglobin. The analytical results are compared with numerically predicted results for IEF, showing excellent agreement. Analytically obtained electric field and ionic conductivity distributions show significant deviation from their nominal values, which is essential in finding the protein focusing behavior at isoelectric points. These analytical solutions can be used to determine steady-state protein concentration distribution for experiment design of IEF considering any number of proteins and ampholytes. Moreover, the model presented herein can be used to find the conductivity, electric field, and pH field. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Apparatus and method for performing electrodynamic focusing on a microchip

DOEpatents

Ramsey, J.M.; Jacobson, S.C.

1999-01-12

A microchip device includes a focusing channel, in which an electric field strength established in the focusing channel is controlled relative to an electric field strength established in a material transport channel segment to spatially focus the material traversing the material transport channel segment. 22 figs.

The "Best Worst" Field Optimization and Focusing

NASA Technical Reports Server (NTRS)

Vaughnn, David; Moore, Ken; Bock, Noah; Zhou, Wei; Ming, Liang; Wilson, Mark

2008-01-01

A simple algorithm for optimizing and focusing lens designs is presented. The goal of the algorithm is to simultaneously create the best and most uniform image quality over the field of view. Rather than relatively weighting multiple field points, only the image quality from the worst field point is considered. When optimizing a lens design, iterations are made to make this worst field point better until such a time as a different field point becomes worse. The same technique is used to determine focus position. The algorithm works with all the various image quality metrics. It works with both symmetrical and asymmetrical systems. It works with theoretical models and real hardware.

Systematic review of maritime field studies about stress and strain in seafaring.

PubMed

Oldenburg, M; Hogan, B; Jensen, H-J

2013-01-01

The aim of this study was to summarize and evaluate the current scientific literature on stress and strain on seafarers on board as defined by maritime field surveys. Using a systematic review, 109 studies on the stress and strain experienced by seafarers were identified for the period January 1990 to January 2012. Only 13 of the identified maritime studies were conducted as field studies, and in 10 of these studies, the focus was on the watch system and/or on fatigue. According to the study results, sleepiness tends to be stronger in the 2-watch system than in the 3-watch system (particularly between 4:00 and 6:00 a.m.). Occasional short sleep episodes appear to provide adequate recovery. Fatigue does not appear to depend on the seafarers' age and is often associated with poor sleep quality; noise and night shifts are also considered to contribute to fatigue. Stress among the seafarers was primarily recorded in sleep diaries (9 times) and with devices for measuring physical activity (4 times). As a rule, a questionnaire was used to assess the strain on the crew on board; 7 studies also additionally recorded biometrical parameters. Only in 6 cases were several groups with different ranks on board investigated. The conducted literature review makes it clear that most maritime field studies have focused on fatigue and watch systems in the shipping industry--in each case as univariate parameters. Thus, scientific field studies with comprehensive multivariate stress and strain analyses on board are required.

Chemical enhanced oil recovery (EOR) activities in Indonesia: How it's future

NASA Astrophysics Data System (ADS)

Abdurrahman, Muslim

2017-05-01

Enhanced oil recovery (EOR) is a proven method for increasing oil production in many oil fields in the world. Huge oil remaining in the reservoir after primary and secondary recovery stage are the main reason for developing EOR methods. Approximately of 49.50 billion barrels oil as a candidate for EOR activities in Indonesia. This present study focuses on the chemical EOR activities involved surfactant and polymer. This research based on pertinent information from various resources such as journal papers, conference papers, and report from the government. Based on this information, this paper explain in detail the progress of each project and it shows the potential oil field employ chemical EOR in the near future. Generally, the EOR activities can be categorized into two phases such as preliminary study phase and field implementation phase. In the preliminary study, the activities simply involve experimental and/or simulation works. Following the preliminary is the field implementation phase which can be categorized into three phases such as field trial, pilot project, and full-scale. In fact, several activities have been conducted by Lemigas (government oil and gas research center), Institut Teknologi Bandung, Institut Pertanian Bogor. These activities focused on laboratory and simulation work. Those institutions have been developing the chemical formula collaborating with oil companies for applying the EOR method in their oil fields. Currently, status of chemical EOR activities include 5 oil fields under pilot project and 12 oil fields under field trial. There are 7 oil fields applying surfactant, 4 oil fields by alkaline-surfactant-polymer (ASP), 2 oil fields by polymer, 1 oil field by surfactant polymer (SP), and 1 oil field by caustic. According to this information, we will have insight knowledge about the EOR current activities, the main issues, future activities on chemical EOR in Indonesia. Moreover, this study can became the preliminary information for researchers who interested conducting further research and development on the chemical EOR activities in the near future.

Stratified flows in complex terrain

NASA Astrophysics Data System (ADS)

Retallack, Charles

The focus of this dissertation is the study of stratified atmospheric flows in the presence of complex terrain. Two large-scale field study campaigns were carried out, each with a focus on a specific archetypal terrain. Each field study involved the utilization of remote and in-situ atmospheric monitoring devices to collect experimental data. The first of the two field studies focused on pollution transport mechanisms near an escarpment. The analysis aimed to determine the combined effect of the escarpment and ambient density stratification on the flow and aerosol pollution transport. It was found that under specific atmospheric conditions, the escarpment prompted the channeling, down-mixing, and trapping of aerosol pollutant plumes. The objective of the second field campaign was the study of stratified flows in a mountain valley. Analysis revealed that buoyancy driven katabatic currents originating on the surrounding valley slopes created a scenario in which a down-slope gravity current transitioned into an intrusive gravity current. The intrusive gravity current propagated near the interface of a density stratified lower ambient layer and a non-stratified upper ambient layer. A combination of shallow water theory and energy arguments is used to produce a model for the propagation of a gravity current moving along the interface of a homogeneous ambient layer and a linearly stratified layer. It is found that the gravity current propagating entirely within the homogeneous layer travels at the greatest speed. As the relative density of the gravity current is increased, the gravity current begins to slump below the interface of the two layers and the propagation speed decreases.

Measuring unintended effects in peacebuilding: What the field of international cooperation can learn from innovative approaches shaped by complex contexts.

PubMed

Lemon, Adrienne; Pinet, Mélanie

2018-06-01

Capturing unintended impacts has been a persistent struggle in all fields of international development, and the field of peacebuilding is no exception. However, because peacebuilding focuses on relationships in complex contexts, the field of peacebuilding has, by necessity, made efforts towards finding practical ways to reflect upon both the intended and unintended effects of this work. To explore what lessons can be learned from the peacebuilding field, this study examines the evaluations of Search for Common Ground, a peacebuilding organisation working in over 35 countries across the world. Analysis focuses on 96 evaluations completed between 2013 and 2016 in 24 countries across Africa, Asia, and the MENA regions that found unintended effects. Programmes focusing on women, youth, and radio were most effective at identifying and explaining unintended effects, likely because the project design guided broader lines of questioning from the beginning. The paper argues that OECD-DAC guidelines are not enough on their own to guide evaluators into exploration of unintended effects, and teams instead need to work together to decide where, when and how they will look for them. Different approaches were also used to capture positive and negative outcomes, suggesting that evaluators need to decide at what level they are evaluating and how to tie effects back to the project's contribution. This study explores evaluation techniques and approaches used to understand impact in complex contexts in the peacebuilding field, and draws on lessons learned for the benefit of other fields dealing with similar complexities in international development and cooperation among actors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Periodontal Research: Basics and beyond - Part I (Defining the research problem, study design and levels of evidence).

PubMed

Avula, Haritha; Pandey, Ruchi; Bolla, Vijayalakshmi; Rao, Harika; Avula, Jaya Kumar

2013-09-01

Research in the field of periodontology has witnessed a tremendous upsurge in the last two decades unveiling newer innovations in techniques, methodologies, and material science. The recent focus in periodontal research is an evidence-based approach which offers a bridge from science to clinical practice. This three part review series intends to take a reader through a maze of periodontal research, unraveling and simplifying various issues in the design, conduct and interpretation of various study designs routinely used in the field of periodontal research. This understanding would facilitate a researcher with a focused and an enhanced vision toward formulating studies which can more efficiently translate sound scientific phenomena into clinically meaningful results.

Periodontal Research: Basics and beyond – Part I (Defining the research problem, study design and levels of evidence)

PubMed Central

Avula, Haritha; Pandey, Ruchi; Bolla, Vijayalakshmi; Rao, Harika; Avula, Jaya Kumar

2013-01-01

Research in the field of periodontology has witnessed a tremendous upsurge in the last two decades unveiling newer innovations in techniques, methodologies, and material science. The recent focus in periodontal research is an evidence-based approach which offers a bridge from science to clinical practice. This three part review series intends to take a reader through a maze of periodontal research, unraveling and simplifying various issues in the design, conduct and interpretation of various study designs routinely used in the field of periodontal research. This understanding would facilitate a researcher with a focused and an enhanced vision toward formulating studies which can more efficiently translate sound scientific phenomena into clinically meaningful results. PMID:24174746

Visual Neuroscience: A Retinal Ganglion Cell to Report Image Focus?

PubMed

Baden, Tom; Schaeffel, Frank; Berens, Philipp

2017-02-20

A recent study describes a mouse neuron projecting from the retina to the brain that exhibits exquisitely high sensitivity to high spatial frequency patterns presented over an unusually large receptive field: could this cell be a (de)focus detector? Copyright © 2017 Elsevier Ltd. All rights reserved.

Development and Validation of Children's Responsible Environmental Behavior Scale

ERIC Educational Resources Information Center

Erdogan, Mehmet; Ok, Ahmet; Marcinkowski, Thomas Joseph

2012-01-01

Though environmentally responsible behavior (ERB) has been a focus of many studies in the field of environmental education, very few scales have been developed to assess children's ERB. In this regard, this article focuses on the development and validation of Children's Responsible Environmental Behavior Scale (CREBS) and also reports the…

Behavioral and Emotional Rating Scale: Two Studies of Convergent Validity

ERIC Educational Resources Information Center

Trout, Alexandra L.; Ryan, Joseph B.; La Vigne, Steven P.; Epstein, Michael H.

2003-01-01

As the field of mental health services shifts its focus to early intervention, the need to develop valid and reliable measures of young children's behavioral functioning is clear. Traditional assessment instruments have focused on deficits, problems, and pathologies to the exclusion of strengths and competencies. However, assessing child strengths…

Perceived Working Conditions and Personal Resources Predicting Mental Health Counselor Well-Being

ERIC Educational Resources Information Center

Thompson, Isabel A.

2012-01-01

This study examined the influence of counselor perceived working conditions, length of time in field, counselor gender, mindfulness attitudes, compassion satisfaction, emotion-focused coping, problem focused coping, and maladaptive coping on levels of burnout and compassion fatigue in a sample of 213 mental health counselors. Cross-sectional…

DIRECT operational field test evaluation : natural use study : part 2 : driver satisfaction in DIRECT controlling for reliability

DOT National Transportation Integrated Search

1998-08-01

This report describes the DIRECT field test which was designed to evaluate the user benefits, institutional issues, and technical issues of en-route driver advisory and traveler information services. Focus was on testing and evaluating the voice-base...

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…

Manpower Management in Canada; A Selected Bibliography. Bibliography Series: No. 3.

ERIC Educational Resources Information Center

Williams, C. Brian

This bibliography is composed of 1,125 citations ranging in date from 1960 to 1966 with a number of pioneering studies, published in the late 1950's, also included. Studies conducted in Canada and the United States are reported for the broad field of manpower and employment. Part I focuses on topics in the fields of employment and unemployment.…

NADE Members Respond--Developmental Education Research Agenda: Survey of Field Professionals, Part 2

ERIC Educational Resources Information Center

Saxon, D. Patrick; Martirosyan, Nara M.; Wentworth, Rebecca A.; Boylan, Hunter R.

2015-01-01

This is the final of a two-part article that provides the results of a qualitative study designed to document ideas and beliefs that professionals have regarding an appropriate research agenda on which the field of developmental education should focus in the near future. The participants of the study were members of the National Association for…

Alternating phase focused linacs

DOEpatents

Swenson, Donald A.

1980-01-01

A heavy particle linear accelerator employing rf fields for transverse and ongitudinal focusing as well as acceleration. Drift tube length and gap positions in a standing wave drift tube loaded structure are arranged so that particles are subject to acceleration and succession of focusing and defocusing forces which contain the beam without additional magnetic or electric focusing fields.

Electrostatic lens to focus an ion beam to uniform density

DOEpatents

Johnson, Cleland H.

1977-01-11

A focusing lens for an ion beam having a gaussian or similar density profile is provided. The lens is constructed to provide an inner zero electrostatic field, and an outer electrostatic field such that ions entering this outer field are deflected by an amount that is a function of their distance from the edge of the inner field. The result is a beam that focuses to a uniform density in a manner analogous to that of an optical ring lens. In one embodiment, a conically-shaped network of fine wires is enclosed within a cylindrical anode. The wire net together with the anode produces a voltage field that re-directs the outer particles of the beam while the axial particles pass undeflected through a zero field inside the wire net. The result is a focused beam having a uniform intensity over a given target area and at a given distance from the lens.

Dynamic Modeling of the Madison Dynamo Experiment

NASA Astrophysics Data System (ADS)

Truitt, J. L.; Forest, C. B.; Wright, J. C.

1999-11-01

This work focuses on a computer simulation of the Magnetohydrodynamic equations applied in the geometry of the Madison Dynamo Experiemnt. An integration code is used to evolve both the magnetic field and the velocity field numerically in spherical coordinates using a pseudo-spectral algorithm. The focus is to realistically model an experiment to be undertaken by the Madison Dynamo Experiment Group. The first flows studied are the well documented ones of Dudley and James. The main goals of the simulation are to observe the dynamo effect with the back-reaction allowed, to observe the equipartition of magnetic and kinetic energy due to theoretically proposed turbulent effects, and to isolate and study the α and β effects.

Electron dynamics in a plasma focus. [electron acceleration

NASA Technical Reports Server (NTRS)

Hohl, F.; Gary, S. P.; Winters, P. A.

1977-01-01

Results are presented of a numerical integration of the three-dimensional relativistic equations of motion of electrons subject to given electric and magnetic fields deduced from experiments. Fields due to two different models are investigated. For the first model, the fields are those due to a circular distribution of axial current filaments. As the current filaments collapse toward the axis, large azimuthal magnetic and axial electric fields are induced. These fields effectively heat the electrons to a temperature of approximately 8 keV and accelerate electrons within the radius of the filaments to high axial velocities. Similar results are obtained for the current-reduction phase of focus formation. For the second model, the fields are those due to a uniform current distribution. Both the current-reduction and the compression phases were studied. These is little heating or acceleration of electrons during the compression phase because the electrons are tied to the magnetic field. However, during the current-reduction phase, electrons near the axis are accelerated toward the center electrode and reach energies of 100 keV. A criterion is obtained which limits the runaway electron current to about 400 A.

First Year Teacher of First Year Teachers: A Reflection on Teacher Training in the Field of Piano Pedagogy

ERIC Educational Resources Information Center

Elgersma, Kristin

2012-01-01

While there is a great deal of scholarly inquiry focusing on student teaching experiences in the field of classroom education, there are few resources devoted to student teaching in the context of the applied music lesson. In this article, a teacher educator in the field of piano pedagogy uses self-study to combine reflection on personal…

Understanding What an Individual Experiencing Work-Family Conflict Finds Helpful While in Counseling: A Case Study

ERIC Educational Resources Information Center

d'Argent, Julie

2014-01-01

According to Aryee, Fields, and Luk (1999), work-family conflict has become a prevalent problem in society. Past research in this area has focused primarily on outcomes and predictors of work-family conflict. Although research found that work-family conflict often leads to mental health concerns, few studies have focused on the area of work-family…

Evolution of a Gaussian laser beam in warm collisional magnetoplasma

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

Jafari, M. J.; Jafari Milani, M. R., E-mail: mrj.milani@gmail.com; Niknam, A. R.

2016-07-15

In this paper, the spatial evolution of an intense circularly polarized Gaussian laser beam propagated through a warm plasma is investigated, taking into account the ponderomotive force, Ohmic heating, external magnetic field, and collisional effects. Using the momentum transfer and energy equations, both modified electron temperature and electron density in plasma are obtained. By introducing the complex dielectric permittivity of warm magnetized plasma and using the complex eikonal function, coupled differential equations for beam width parameter are established and solved numerically. The effects of polarization state of laser and magnetic field on the laser spot size evolution are studied. Itmore » is observed that in case of the right-handed polarization, an increase in the value of external magnetic field causes an increase in the strength of the self-focusing, especially in the higher values, and consequently, the self-focusing occurs in shorter distance of propagation. Moreover, the results demonstrate the existence of laser intensity and electron temperature ranges where self-focusing can occur, while the beam diverges outside of these regions; meanwhile, in these intervals, there exists a turning point for each of intensity and temperature in which the self-focusing process has its strongest strength. Finally, it is found that the self-focusing effect can be enhanced by increasing the plasma frequency (plasma density).« less

Creativity and Education: An American Retrospective

ERIC Educational Resources Information Center

Feldman, David Henry; Benjamin, Ann C.

2006-01-01

Although early childhood education in America has always had the creative child at the core of its approach, the field itself has generated little systematic research on the topic. In contrast, the scholarly field of creativity studies, with its focus on basic research and theoretical questions, has impacted education only slightly. Creativity and…

Structuralization of Doctoral Education in Germany: An Interdisciplinary Comparison

ERIC Educational Resources Information Center

Qin, Lin

2017-01-01

Taking the establishment of structured doctoral programmes in Germany as an example, this paper focuses on how knowledge production in certain academic fields reshapes their doctoral education in a widely changing policy context. Based on case studies of eight graduate schools in three research fields, namely economics, life sciences, and…

Law-and-Education Research: Past and Future.

ERIC Educational Resources Information Center

Yudof, Mark G.

1979-01-01

The author traces the development of this new field of legal study concerning the interface of law and educational policy. Finding the field's current approach misdirected through overemphasis on reform and the Constitution, he suggests a new paradigm, law-in-action, with a broader focus drawn from related disciplines. (SJL)

Day Jobs/Nightwork: Academic Staff Studying towards Higher Degrees

ERIC Educational Resources Information Center

Winberg, C.; Adams, A.; Esbach, J.; Groenewald, W.; Lakay, D.; Muzondo, I.; Randall, K.; Seane, G.; Siyepu, S.; Veeran, P.

2010-01-01

Universities of Technology (UTs) offer career-focused education in a wide variety of disciplines and fields. Traditionally, UTs recruited academic staff with relevant workplace experience, rather than academic qualifications. The result of this strategy was, while many lecturers possessed professional qualifications in their field, they did not…

78 FR 30899 - Agency Information Collection Activities; Comment Request; NCES Cognitive, Pilot, and Field Test...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-23

...; Comment Request; NCES Cognitive, Pilot, and Field Test Studies System AGENCY: Institute of Education... in response to this notice will be considered public records. Title of Collection: NCES Cognitive... with levels of incentives for various types of survey operations, focus groups, cognitive laboratory...

Vector optical fields with polarization distributions similar to electric and magnetic field lines.

PubMed

Pan, Yue; Li, Si-Min; Mao, Lei; Kong, Ling-Jun; Li, Yongnan; Tu, Chenghou; Wang, Pei; Wang, Hui-Tian

2013-07-01

We present, design and generate a new kind of vector optical fields with linear polarization distributions modeling to electric and magnetic field lines. The geometric configurations of "electric charges" and "magnetic charges" can engineer the spatial structure and symmetry of polarizations of vector optical field, providing additional degrees of freedom assisting in controlling the field symmetry at the focus and allowing engineering of the field distribution at the focus to the specific applications.

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.

Pb/InAs nanowire josephson junction with high critical current and magnetic flux focusing.

PubMed

Paajaste, J; Amado, M; Roddaro, S; Bergeret, F S; Ercolani, D; Sorba, L; Giazotto, F

2015-03-11

We have studied mesoscopic Josephson junctions formed by highly n-doped InAs nanowires and superconducting Ti/Pb source and drain leads. The current-voltage properties of the system are investigated by varying temperature and external out-of-plane magnetic field. Superconductivity in the Pb electrodes persists up to ∼7 K and with magnetic field values up to 0.4 T. Josephson coupling at zero backgate voltage is observed up to 4.5 K and the critical current is measured to be as high as 615 nA. The supercurrent suppression as a function of the magnetic field reveals a diffraction pattern that is explained by a strong magnetic flux focusing provided by the superconducting electrodes forming the junction.

Correlation of the neutron yield from the plasma focus upon variations in the magnetic field energy of the discharge circuit

NASA Astrophysics Data System (ADS)

Ablesimov, V. E.; Dolin, Yu. N.; Kalinychev, A. E.; Tsibikov, Z. S.

2017-10-01

The relation between neutron yield Y and magnetic field energy variations Δ W in the discharge circuit has been studied for a Mather-type plasma-focus camera. The activation technique (activation of silver isotopes) has been used to measure the integral yield of DD neutrons from the source. The time dependence of the neutron yield has been recorded by scintillation detectors. For the device used in the investigations, the neutron yield exhibits a linear dependence on variations in the magnetic field energy Δ W in the discharge circuit at the instant of neutron generation. It is also found that this dependence is related to the initial deuteron pressure in the discharge chamber.

[Public health and mental health: methodological tools to evaluate the Brazilian Network of Referral Centers for Psycho-Social Care (CAPS) in the Brazilian Unified Health System].

PubMed

Onocko-Campos, Rosana Teresa; Furtado, Juarez Pereira

2006-05-01

This article presents a preliminary discussion of potential methodological tools for qualitative research on the Network of Referral Centers for Psycho-Social Care (CAPS) in the Brazilian Unified Health System (SUS). The relevance of mental health within the field of public health is examined. The study focuses on the high prevalence of mental disorders and the disproportionate lack of studies on the interface between mental health and public health. The establishment of an interdisciplinary field between public health and mental health is proposed to meet common needs by achieving similar perspectives in knowledge and practice. A particular group of tools is proposed, emphasizing the importance of reclaiming and guaranteeing the roles of various social actors to shape the assessment process, the need for collecting and standardizing academic studies on the topic, and the importance of promoting a new research field focusing on public health policies to support policymakers, managers, and health teams in reshaping their practices.

Investigating the strategic antecedents of agility in humanitarian logistics.

PubMed

L'Hermitte, Cécile; Brooks, Benjamin; Bowles, Marcus; Tatham, Peter H

2017-10-01

This study investigates the strategic antecedents of operational agility in humanitarian logistics. It began by identifying the particular actions to be taken at the strategic level of a humanitarian organisation to support field-level agility. Next, quantitative data (n=59) were collected on four strategic-level capabilities (being purposeful, action-focused, collaborative, and learning-oriented) and on operational agility (field responsiveness and flexibility). Using a quantitative analysis, the study tested the relationship between organisational capacity building and operational agility and found that the four strategic-level capabilities are fundamental building blocks of agility. Collectively they account for 52 per cent of the ability of humanitarian logisticians to deal with ongoing changes and disruptions in the field. This study emphasises the need for researchers and practitioners to embrace a broader perspective of agility in humanitarian logistics. In addition, it highlights the inherently strategic nature of agility, the development of which involves focusing simultaneously on multiple drivers. © 2017 The Author(s). Disasters © Overseas Development Institute, 2017.

Papers published from 1995 to 2012 by six Traditional Chinese Medicine universities in China: a bibliometric analysis based on science citation index.

PubMed

Gao, Kuo; Tian, Guihua; Ye, Qing; Zhai, Xing; Chen, Jianxin; Liu, Tiegang; Liu, Kaifeng; Zhao, Jingyi; Ding, Shengyun

2013-12-01

The quality and quantity of published research papers are important in both scientific and technology fields. Although there are several bibliometric studies based on citation analysis, very few have focused on research related to Traditional Chinese Medicine in China. The bibliometric method used in this study included the following focuses: publication outputs for each year, paper type, language of publication, distribution of internationally collaborative countries, sources of funding, authorization number, distribution of institutes regarding collaborative publications, research fields, distribution of outputs in journals, citation, data, and h-index. A total of 3809 papers published from 1995 to 2012 were extracted from the science citation index (SCI). The cumulative number of papers from all six universities is constantly increasing. The United States attained the dominant position regarding complementary and alternative medicine research. The Chinese Academy of Sciences was the greatest participator in collaborative efforts. Research field analysis showed that the research mainly focused on pharmacology pharmacy, chemistry, integrative complementary medicine, plant sciences, and biochemistry molecular biology. The Shanghai University of Chinese Medicine had the most citations. In recent years, in terms of SCI papers, the six Traditional Chinese Medicine universities studied here have made great advances in scientific research.

Variability in electromagnetic field levels over time, and Monte-Carlo simulation of exposure parameters.

PubMed

Pachón-García, F T; Paniagua-Sánchez, J M; Rufo-Pérez, M; Jiménez-Barco, A

2014-12-01

This article analyses the electric field levels around medium-wave transmitters, delimiting the temporal variability of the levels received at a pre-established reception point. One extensively used dosimetric criterion is to consider historical levels of the field recorded over a certain period of time so as to provide an overall perspective of radio-frequency electric field exposure in a particular environment. This aspect is the focus of the present study, in which the measurements will be synthesised in the form of exposure coefficients. Two measurement campaigns were conducted: one short term (10 days) and the other long term (1 y). The short-term data were used to study which probability density functions best approximate the measured levels. The long-term data were used to compute the principal statistics that characterise the field values over a year. The data that form the focus of the study are the peak traces, since these are the most representative from the standpoint of exposure. The deviations found were around 6 % for short periods and 12 % for long periods. The information from the two campaigns was used to develop and implement a computer application based on the Monte Carlo method to simulate values of the field, allowing one to carry out robust statistics. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Impact of multi-focused images on recognition of soft biometric traits

NASA Astrophysics Data System (ADS)

Chiesa, V.; Dugelay, J. L.

2016-09-01

In video surveillance semantic traits estimation as gender and age has always been debated topic because of the uncontrolled environment: while light or pose variations have been largely studied, defocused images are still rarely investigated. Recently the emergence of new technologies, as plenoptic cameras, yields to deal with these problems analyzing multi-focus images. Thanks to a microlens array arranged between the sensor and the main lens, light field cameras are able to record not only the RGB values but also the information related to the direction of light rays: the additional data make possible rendering the image with different focal plane after the acquisition. For our experiments, we use the GUC Light Field Face Database that includes pictures from the First Generation Lytro camera. Taking advantage of light field images, we explore the influence of defocusing on gender recognition and age estimation problems. Evaluations are computed on up-to-date and competitive technologies based on deep learning algorithms. After studying the relationship between focus and gender recognition and focus and age estimation, we compare the results obtained by images defocused by Lytro software with images blurred by more standard filters in order to explore the difference between defocusing and blurring effects. In addition we investigate the impact of deblurring on defocused images with the goal to better understand the different impacts of defocusing and standard blurring on gender and age estimation.

Electrostatically focused addressable field emission array chips (AFEA's) for high-speed massively parallel maskless digital E-beam direct write lithography and scanning electron microscopy

DOEpatents

Thomas, Clarence E.; Baylor, Larry R.; Voelkl, Edgar; Simpson, Michael L.; Paulus, Michael J.; Lowndes, Douglas H.; Whealton, John H.; Whitson, John C.; Wilgen, John B.

2002-12-24

Systems and methods are described for addressable field emission array (AFEA) chips. A method of operating an addressable field-emission array, includes: generating a plurality of electron beams from a pluralitly of emitters that compose the addressable field-emission array; and focusing at least one of the plurality of electron beams with an on-chip electrostatic focusing stack. The systems and methods provide advantages including the avoidance of space-charge blow-up.

The Impact of Field Experiences in Yellowstone National Park on Practice in Secondary Classrooms

ERIC Educational Resources Information Center

McGrew, Christopher N.

2012-01-01

The current study focused on how six participants of a 2009 professional development activity at Yellowstone National Park described their experience and classroom instructional impact. The author focused on words and phrases illustrating perspective gathering, reflection and public performance to determine the impact of both the experience at…

Abbreviated Military Decision Making for Brigade Combat Teams

DTIC Science & Technology

2001-06-01

manual, The Enlighted Eye. The current study is field focused, includes self as an instrument, is essentially interpretive in scope, focuses on details...decision making performance deteriorated when more rather than less information was provided.”51 Even under normal circumstances, current technology ...Direct Military Support (10) / Chapter 3 / 12 Critical Technology (3

Superconducting focusing lenses for the SSR-1 cryomodule of PXIE test stand at Fermilab

DOE PAGES

DiMarco, J.; Tartaglia, M.; Terechkine, I.

2016-12-05

Five solenoid-based focusing lenses designed for use inside the SSR1 cryomodule of the PXIE test stand at Fermilab have been fabricated and tested. In addition to a focusing solenoid, each lens is equipped with a set of windings that generate magnetic field in the transverse plane and can be used in the steering dipole mode or as a skew quadrupole corrector. The lenses will be installed between superconducting cavities in the cryomodule, so getting sufficiently low fringe magnetic field was one of the main design requirements. Beam dynamics simulations indicated a need for high accuracy positioning of the lenses inmore » the cryomodule, which triggered a study towards understanding uncertainties of the magnetic axis position relative to the geometric features of the lens. Furthermore, this report summarizes the efforts towards certification of the lenses, including results of performance tests, fringe field data, and uncertainty of the magnetic axis position.« less

Superconducting focusing lenses for the SSR-1 cryomodule of PXIE test stand at Fermilab

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

DiMarco, J.; Tartaglia, M.; Terechkine, I.

Five solenoid-based focusing lenses designed for use inside the SSR1 cryomodule of the PXIE test stand at Fermilab have been fabricated and tested. In addition to a focusing solenoid, each lens is equipped with a set of windings that generate magnetic field in the transverse plane and can be used in the steering dipole mode or as a skew quadrupole corrector. The lenses will be installed between superconducting cavities in the cryomodule, so getting sufficiently low fringe magnetic field was one of the main design requirements. Beam dynamics simulations indicated a need for high accuracy positioning of the lenses inmore » the cryomodule, which triggered a study towards understanding uncertainties of the magnetic axis position relative to the geometric features of the lens. Furthermore, this report summarizes the efforts towards certification of the lenses, including results of performance tests, fringe field data, and uncertainty of the magnetic axis position.« less

Adaptive DOF for plenoptic cameras

NASA Astrophysics Data System (ADS)

Oberdörster, Alexander; Lensch, Hendrik P. A.

2013-03-01

Plenoptic cameras promise to provide arbitrary re-focusing through a scene after the capture. In practice, however, the refocusing range is limited by the depth of field (DOF) of the plenoptic camera. For the focused plenoptic camera, this range is given by the range of object distances for which the microimages are in focus. We propose a technique of recording light fields with an adaptive depth of focus. Between multiple exposures { or multiple recordings of the light field { the distance between the microlens array (MLA) and the image sensor is adjusted. The depth and quality of focus is chosen by changing the number of exposures and the spacing of the MLA movements. In contrast to traditional cameras, extending the DOF does not necessarily lead to an all-in-focus image. Instead, the refocus range is extended. There is full creative control about the focus depth; images with shallow or selective focus can be generated.

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.

Focusators for laser-branding

NASA Astrophysics Data System (ADS)

Doskolovich, L. L.; Kazanskiy, N. L.; Kharitonov, S. I.; Uspleniev, G. V.

A new method is investigated for synthesis of computer-generated optical elements: focusators that are able to focus the radial-symmetrical laser beam into complex focal contours, in particular into alphanumeric symbols. The method is based on decomposition of the focal contour into segments of straight lines and semi-circles, following corresponding spacing out of the focusator on elementary segments (concentric rings or sectors) and solution of the inverse task of focusing from focusator segments into corresponding elements of the focal contour. The results of numerical computing of the field from synthesized focusators into the letters are presented. The theoretical efficiency of the focusators discussed is no less than 85%. The amplitude masks and the results of operational studies of synthesized focusators are presented.

Predicting Engineering Student Attrition Risk Using a Probabilistic Neural Network and Comparing Results with a Backpropagation Neural Network and Logistic Regression

ERIC Educational Resources Information Center

Mason, Cindi; Twomey, Janet; Wright, David; Whitman, Lawrence

2018-01-01

As the need for engineers continues to increase, a growing focus has been placed on recruiting students into the field of engineering and retaining the students who select engineering as their field of study. As a result of this concentration on student retention, numerous studies have been conducted to identify, understand, and confirm…

Radiofrequency heating of nanomaterials for cancer treatment: Progress, controversies, and future development

NASA Astrophysics Data System (ADS)

Liu, Xiaoming; Chen, Hui-jiuan; Chen, Xiaodong; Alfadhl, Yasir; Yu, Junsheng; Wen, Dongsheng

2015-03-01

In recent years, the application of nanomaterials to biological and biomedicine areas has attracted intensive interest. One of the hot topics is the nanomaterial mediated radiofrequency (RF) hyperthermia or ablation, i.e., using RF fields/waves to heat tumor tissues treated with nanomaterials to destroy cancerous cells while minimizing the side-heating effect. However, there are currently many contradictive results reported concerning the heating effect of nanomaterials under a RF field. This paper provided a comprehensive review to nanomaterial mediated RF ablation from both experimental and theoretical aspects. Three heating mechanisms were discussed, i.e., laser heating, magnetic field heating, and electric field heating in RF spectrum, with the focus on the last one. The results showed that while diluted pure metallic nanoparticles could be heated significantly by a laser through the surface plasmon resonance, they cannot be easily heated by a RF electric field. Further studies are proposed focusing on nanoparticle structure and morphology, electromagnetic frequency and localized heating effect to pave the way for future development.

Repetitive thinking about the mother during distress moderates the link between children's attentional breadth around the mother and depressive symptoms in middle childhood.

PubMed

Van de Walle, Magali; Bijttebier, Patricia; De Raedt, Rudi; Bosmans, Guy

2017-03-01

It has been suggested that an increased attentional focus on the mother should be maladaptive in middle childhood. However, the effect of a more narrow attentional field around the mother may depend on the mother-child relationship. The current study tested whether a more narrow attentional field around the mother is mainly maladaptive for children who tend to think repetitively about their mother (RTm) during distress. More specifically, it investigates whether RTm during distress provides the context in which an increased attentional focus on the mother is linked to depressive symptoms in middle childhood. RTm was measured using a self-report questionnaire. The breadth of children's attentional field around the mother was measured with the Attentional Breadth Task. This computer task assesses the extent to which children have a more narrow attentional field around the mother compared to unfamiliar women. Results of the current study (N = 157) support the hypothesis that 9-12 year old children who have a more narrow attentional field around the mother and who at the same time report more RTm during distress, have more depressive symptoms. Copyright © 2016 Elsevier Ltd. All rights reserved.

A focusing reflectarray and its application in microwave virus sanitizer

NASA Astrophysics Data System (ADS)

Hung, Wan-Ting; Tung, Jen-Jung; Chen, Shih-Yuan

2014-10-01

In this paper, a focusing reflectarray based on the conductor-backed strip dipole unit cell is proposed and designed for use in the microwave virus sanitizer. Unlike traditional far-field antennas that form a planar phase front in a specified far-field direction, the focusing reflectarray is designed to coherently add the fields radiated from the feeding antenna at a predetermined focal point, typically within its radiating near-field region and to ensure adequate power density to inactivate the H3N2 virus sample. Furthermore, the focusing reflectarray has a simple and planar structure compared with conventional focusing antennas. Since the microwave resonant absorption frequency of the H3N2 virus is at about 8 GHz, an 8 × 8 focusing reflectarray is designed for operation at 8 GHz. A prototype antenna is then fabricated and used for H3N2 virus sanitization. It is demonstrated experimentally that the death rate of the H3N2 virus sample is up to 93%, verifying the feasibility of the microwave virus sanitizer as well as the proposed focusing reflectarray.

An efficient method for the fusion of light field refocused images

NASA Astrophysics Data System (ADS)

Wang, Yingqian; Yang, Jungang; Xiao, Chao; An, Wei

2018-04-01

Light field cameras have drawn much attention due to the advantage of post-capture adjustments such as refocusing after exposure. The depth of field in refocused images is always shallow because of the large equivalent aperture. As a result, a large number of multi-focus images are obtained and an all-in-focus image is demanded. Consider that most multi-focus image fusion algorithms do not particularly aim at large numbers of source images and traditional DWT-based fusion approach has serious problems in dealing with lots of multi-focus images, causing color distortion and ringing effect. To solve this problem, this paper proposes an efficient multi-focus image fusion method based on stationary wavelet transform (SWT), which can deal with a large quantity of multi-focus images with shallow depth of fields. We compare SWT-based approach with DWT-based approach on various occasions. And the results demonstrate that the proposed method performs much better both visually and quantitatively.

Role of Focus-on-Form Instruction, Corrective Feedback and Uptake in Second Language Classrooms: Some Insights from Recent Second Language Acquisition Research

ERIC Educational Resources Information Center

Afitska, Oksana

2015-01-01

A considerable number of studies on focus-on-form instruction, corrective feedback and uptake have been carried out in the field of second language acquisition (SLA) research over the last two decades. These studies have investigated the above-mentioned concepts from different perspectives, in a number of different contexts and in a number of…

Brownian motion of electrons in time-dependent magnetic fields.

NASA Technical Reports Server (NTRS)

Iverson, G. J.; Williams, R. M.

1973-01-01

The behavior of a weakly ionized plasma in slowly varying time-dependent magnetic fields is studied through an extension of Williamson's stochastic theory. In particular, attention is focused on the properties of electron diffusion in the plane perpendicular to the direction of the magnetic field, when the field strength is large. It is shown that, in the strong field limit, the classical 1/B-squared dependence of the perpendicular diffusion coefficient is obtained for two models in which the field B(t) is monotonic in t and for two models in which B(t) possesses at least one turning point.

Vector fields in a tight laser focus: comparison of models.

PubMed

Peatross, Justin; Berrondo, Manuel; Smith, Dallas; Ware, Michael

2017-06-26

We assess several widely used vector models of a Gaussian laser beam in the context of more accurate vector diffraction integration. For the analysis, we present a streamlined derivation of the vector fields of a uniformly polarized beam reflected from an ideal parabolic mirror, both inside and outside of the resulting focus. This exact solution to Maxwell's equations, first developed in 1920 by V. S. Ignatovsky, is highly relevant to high-intensity laser experiments since the boundary conditions at a focusing optic dictate the form of the focus in a manner analogous to a physical experiment. In contrast, many models simply assume a field profile near the focus and develop the surrounding vector fields consistent with Maxwell's equations. In comparing the Ignatovsky result with popular closed-form analytic vector models of a Gaussian beam, we find that the relatively simple model developed by Erikson and Singh in 1994 provides good agreement in the paraxial limit. Models involving a Lax expansion introduce a divergences outside of the focus while providing little if any improvement in the focal region. Extremely tight focusing produces a somewhat complicated structure in the focus, and requires the Ignatovsky model for accurate representation.

Overview of NASA FINESSE (Field Investigations to Enable Solar System Science and Exploration) Science and Exploration Results

NASA Technical Reports Server (NTRS)

Heldmann, Jennifer L.; Lim, Darlene S. S.; Hughes, S.; Kobs, S.; Garry, B.; Osinski, G. R.; Hodges, K.; Kobayashi, L.; Colaprete, A.

2015-01-01

NASA's FINESSE (Field Investigations to Enable Solar System Science and Exploration) project is focused on a science and exploration field-based research program to generate strategic knowledge in preparation for human and robotic exploration of other planetary bodies including our moon, Mars' moons Phobos and Deimos, and near-Earth asteroids. Scientific study focuses on planetary volcanism (e.g., the formation of volcanoes, evolution of magma chambers and the formation of multiple lava flow types, as well as the evolution and entrapment of volatile chemicals) and impact cratering (impact rock modification, cratering mechanics, and the chronologic record). FINESSE conducts multiple terrestrial field campaigns (Craters of the Moon National Monument and Preserve in Idaho for volcanics, and West Clearwater Impact Structure in Canada for impact studies) to study such features as analogs relevant to our moon, Phobos, Deimos, and asteroids. Here we present the science and exploration results from two deployments to Idaho (2014, 2015) and our first deployment to Canada (2014). FINESSE was selected as a research team by NASA's Solar System Exploration Research Virtual Institute (SSERVI). SSERVI is a joint effort by NASA's Science Mission Directorate (SMD) and Human Exploration and Operations Mission Directorate (HEOMD).

Introduction to the Special Issue.

ERIC Educational Resources Information Center

Petrosino, Anthony

2003-01-01

Introduces the articles of this special issue focusing on randomized field trials in criminology. In spite of the overall lack of randomized field trials in criminology, some agencies and individuals are able to mount an impressive number of field trials, and these articles focus on their experiences. (SLD)

Ultrasound field measurement using a binary lens

PubMed Central

Clement, G.T.; Nomura, H.; Kamakura, T.

2014-01-01

Field characterization methods using a scattering target in the absence of a point-like receiver have been well described in which scattering is recorded by a relatively large receiver located outside the field of measurement. Unfortunately, such methods are prone to artifacts due to averaging across the receiver surface. To avoid this problem while simultaneously increasing the gain of a received signal, the present study introduces a binary plate lens designed to focus spherically-spreading waves onto a planar region having a nearly-uniform phase proportional to that of the target location. The lens is similar to a zone plate, but modified to produce a biconvex-like behavior, such that it focuses both planar and spherically spreading waves. A measurement device suitable for characterizing narrowband ultrasound signals in air is designed around this lens by coupling it to a target and planar receiver. A prototype device is constructed and used to characterize the field of a highly-focused 400 kHz air transducer along 2 radial lines. Comparison of the measurements with numeric predictions formed from nonlinear acoustic simulation showed good relative pressure correlation, with mean differences of 10% and 12% over center 3dB FWHM drop and 12% and 17% over 6dB. PMID:25643084

Using object-based image analysis to guide the selection of field sample locations

USDA-ARS?s Scientific Manuscript database

One of the most challenging tasks for resource management and research is designing field sampling schemes to achieve unbiased estimates of ecosystem parameters as efficiently as possible. This study focused on the potential of fine-scale image objects from object-based image analysis (OBIA) to be u...

From Management to Leadership: Semantic or Meaningful Change?

ERIC Educational Resources Information Center

Bush, Tony

2008-01-01

Educational management was still a relatively new field of study and practice in the UK at the time of the Education Reform Act (ERA) 1988. The field focused on "management" and not leadership. This emphasis very much reflected the business world and its use in education illustrated the "policy borrowing" characteristic of an…

Elites, Bureaucrats, Ostriches, and Pussycats: Managing Research in Policy Settings.

ERIC Educational Resources Information Center

Marshall, Catherine

Female researchers conducting field research in educational politics encounter special problems of access, entry, reciprocity, and ethics. Accordingly, this study focuses first on field research methods in policy settings as a general topic, then on problems specific to women in this area. A researcher must be aware of informal coalitions or…

Geography Education Research and Why It Matters

ERIC Educational Resources Information Center

Lambert, David

2010-01-01

This paper provides a commentary on the "condition" of geography education research as a field of study. It does so partly through a comparative discussion with another subject field in education, mathematics. In the context of fragility and comparative weakness of research in geography education, the paper urges researchers to keep focused on…

Engaging Preservice Teachers in Disciplinary Literacy Learning through Writing

ERIC Educational Resources Information Center

Pytash, Kristine E.

2012-01-01

The field of content area literacy instruction is shifting from a general understanding of literacy towards disciplinary literacy. Much of the work in the field of disciplinary literacy has focused on reading, while writing has often been overlooked. This article summarizes the findings of a qualitative case study of two preservice teachers as…

Adult Education & Human Resource Development: Overlapping and Disparate Fields

ERIC Educational Resources Information Center

Watkins, Karen E.; Marsick, Victoria J.

2014-01-01

Adult education and human resource development as fields of practice and study share some roots in common but have grown in different directions in their histories. Adult education's roots focused initially on citizenship for a democratic society, whereas human resource development's roots are in performance at work. While they have…

Teachers Curriculum Guide for Field Ecology.

ERIC Educational Resources Information Center

Bemiss, Clair W.

Focusing upon a working knowledge of ecological principles as a requisite for today's society, this teacher's guide suggests numerous field studies which make pertinent use of these principles. It is designed to serve as an aid in planning student-centered activities which allow for understanding and improving the ecosystem in which they are an…

A case study of urban student and teacher experiences surrounding an outdoor environmental science field trip

NASA Astrophysics Data System (ADS)

Preusch, Peggy L.

2009-12-01

Field trips provide opportunities for students to experience many different contexts beyond the classroom, and are a popular choice of K-12 teachers in the US. Recent interest in learning that occurs at informal science education centers such as museums, zoos and aquariums has stimulated studies of the relationship between learning in and outside of schools. Although many studies focus on the teachers, the contexts, and/or the students during the field trip, only a few look at the entire process of learning by including the classroom setting before and after the field trip. This study was designed to develop understandings of the student process of learning during and surrounding an environmental science field trip to an outdoor setting. John Dewey's extensive writings on the relationship between experience and learning informed the analysis, creating a focus on active and passive elements of the experience, continuity within and across contexts, the interactive nature of the experience and the importance of subject matter. An exploration of environmental education (EE), environmental science (ES), and nature study as content revealed the complexities of the subject matter of the field trip that make its presentation problematic. An urban school was chosen to contribute to the research literature about urban student learning in outdoor environments. During the field trip, the students' active engagement with each other and the environment supported meaningful remembrances of the field trip experiences during interviews after the field trip. The students accurately described plants and animals they had observed in different habitats during the field trip. They also made connections with their home life and prior experiences in the outdoors as they discussed the field trip and drew pictures that represented their experiences. One student integrated his outdoor experience with a language arts assignment as he reflected deeply on the field trip. One implication of this study is that educational experiences in outdoor natural environments are complex in ways that contribute to lack of continuity between science lessons in an elementary classroom and environmental science field trip. Long term relationships between schools and informal settings that recognize the strengths of both contexts in terms of student learning processes surrounding field trip experiences are needed to strengthen the educative process for field trip participants.

Going the Distance.

ERIC Educational Resources Information Center

Leno, Arthur J.

2003-01-01

Describes the development and implementation of the distance education program at Peirce College. This Internet-mediated distance learning program focuses on practical fields of study, drawing on the college's strengths in business administration, information technology, and paralegal studies. (SLD)

Interdisciplinary Working Practices: Can Creative Dance Improve Math?

ERIC Educational Resources Information Center

Leandro, Cristina Rebelo; Monteiro, Elisabete; Melo, Filipe

2018-01-01

This study is integrated in the field of Dance in Education, focusing on the instrumentalist aspect of art. We focused on creative dance as a catalyst to learn Mathematics' contents. This interdisciplinary work can enhance the learning, as far as the understanding of Mathematics' concepts is achieved through the body and revealed by expressive and…

Individualized Child-Focused Curriculum: A Differentiated Approach

ERIC Educational Resources Information Center

Gronlund, Gaye

2016-01-01

How do you focus on each individual child in a full classroom? Learn to integrate individualized curriculum into daily practice with this step-­by-­step guide. Even good observers and documenters do not always use these insights to inform their curriculum planning. Using Developmental Studies, a new tool created and successfully field­-tested by…

Deliberative Communication Goes to College: The "Deliberation Forum" Project as a Democratic Agent of Empowerment for Communication Students

ERIC Educational Resources Information Center

Malka, Vered

2016-01-01

A new field of research has developed over the last few decades, called "Deliberative Communication". It focuses on the potential contribution of public deliberations to strengthening the foundations of democracy and the promotion of social-political goals and objectives. The current research focuses on a unique case study, the…

Older people in the field of medication.

PubMed

2002-07-01

Focus group methodology is becoming ever more popular in healthcare research. In this Finnish study, five focus group discussions were conducted with a total of 34 participants whose ages ranged from 65 to 85. Each group was facilitated by two researchers and the discussions were tape-recorded. Analysis of the data employed the concepts developed by Pierre Bourdieu.

Medical telementoring using an augmented reality transparent display.

PubMed

Andersen, Daniel; Popescu, Voicu; Cabrera, Maria Eugenia; Shanghavi, Aditya; Gomez, Gerardo; Marley, Sherri; Mullis, Brian; Wachs, Juan P

2016-06-01

The goal of this study was to design and implement a novel surgical telementoring system called the System for Telementoring with Augmented Reality (STAR) that uses a virtual transparent display to convey precise locations in the operating field to a trainee surgeon. This system was compared with a conventional system based on a telestrator for surgical instruction. A telementoring system was developed and evaluated in a study which used a 1 × 2 between-subjects design with telementoring system, that is, STAR or conventional, as the independent variable. The participants in the study were 20 premedical or medical students who had no prior experience with telementoring. Each participant completed a task of port placement and a task of abdominal incision under telementoring using either the STAR or the conventional system. The metrics used to test performance when using the system were placement error, number of focus shifts, and time to task completion. When compared with the conventional system, participants using STAR completed the 2 tasks with less placement error (45% and 68%) and with fewer focus shifts (86% and 44%), but more slowly (19% for each task). Using STAR resulted in decreased annotation placement error, fewer focus shifts, but greater times to task completion. STAR placed virtual annotations directly onto the trainee surgeon's field of view of the operating field by conveying location with great accuracy; this technology helped to avoid shifts in focus, decreased depth perception, and enabled fine-tuning execution of the task to match telementored instruction, but led to greater times to task completion. Copyright © 2016 Elsevier Inc. All rights reserved.

Introduction to Focus Issue: nonlinear and stochastic physics in biology.

PubMed

Bahar, Sonya; Neiman, Alexander B; Jung, Peter; Kurths, Jürgen; Schimansky-Geier, Lutz; Showalter, Kenneth

2011-12-01

Frank Moss was a leading figure in the study of nonlinear and stochastic processes in biological systems. His work, particularly in the area of stochastic resonance, has been highly influential to the interdisciplinary scientific community. This Focus Issue pays tribute to Moss with articles that describe the most recent advances in the field he helped to create. In this Introduction, we review Moss's seminal scientific contributions and introduce the articles that make up this Focus Issue.

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.

Multi-focused microlens array optimization and light field imaging study based on Monte Carlo method.

PubMed

Li, Tian-Jiao; Li, Sai; Yuan, Yuan; Liu, Yu-Dong; Xu, Chuan-Long; Shuai, Yong; Tan, He-Ping

2017-04-03

Plenoptic cameras are used for capturing flames in studies of high-temperature phenomena. However, simulations of plenoptic camera models can be used prior to the experiment improve experimental efficiency and reduce cost. In this work, microlens arrays, which are based on the established light field camera model, are optimized into a hexagonal structure with three types of microlenses. With this improved plenoptic camera model, light field imaging of static objects and flame are simulated using the calibrated parameters of the Raytrix camera (R29). The optimized models improve the image resolution, imaging screen utilization, and shooting range of depth of field.

Field studies of Pan troglodytes reviewed and comprehensively mapped, focussing on Japan's contribution to cultural primatology.

PubMed

McGrew, William C

2017-01-01

Field studies done over decades of wild chimpanzees in East, Central and West Africa have yielded impressive, cumulative findings in cultural primatology. Japanese primatologists have been involved in this advance from the outset, over a wide variety of topics. Here I review the origins and development of field studies of Pan troglodytes, then assess their progress based on analogy between cultural primatology and cultural anthropology, through four stages: natural history, ethnography, ethnology, and intuition. Then, I focus on six topics that continue to yield informative debate: technology, universals, nuanced variation, archaeology, applied primatology, and ecology. Finally, I offer a map of sites of field study of wild chimpanzees. It is clear that Japanese primatologists have made a significant contribution to East-West scientific exchange, especially at the field sites of Bossou and Mahale.

Self-excitation of microwave oscillations in plasma-assisted slow-wave oscillators by an electron beam with a movable focus

NASA Astrophysics Data System (ADS)

Bliokh, Yu. P.; Nusinovich, G. S.; Shkvarunets, A. G.; Carmel, Y.

2004-10-01

Plasma-assisted slow-wave oscillators (pasotrons) operate without external magnetic fields, which makes these devices quite compact and lightweight. Beam focusing in pasotrons is provided by ions, which appear in the device due to the impact ionization of a neutral gas by beam electrons. Typically, the ionization time is on the order of the rise time of the beam current. This means that, during the rise of the current, beam focusing by ions becomes stronger. Correspondingly, a beam of electrons, which was initially diverging radially due to the self-electric field, starts to be focused by ions, and this focus moves towards the gun as the ion density increases. This feature makes the self-excitation of electromagnetic (em) oscillations in pasotrons quite different from practically all other microwave sources where em oscillations are excited by a stationary electron beam. The process of self-excitation of em oscillations has been studied both theoretically and experimentally. It is shown that in pasotrons, during the beam current rise the amount of current entering the interaction space and the beam coupling to the em field vary. As a result, the self-excitation can proceed faster than in conventional microwave sources with similar operating parameters such as the operating frequency, cavity quality-factor and the beam current and voltage.

Study of multi-level atomic systems with the application of magnetic field

NASA Astrophysics Data System (ADS)

Hu, Jianping; Roy, Subhankar; Ummal Momeen, M.

2018-04-01

The complexity of multiple energy levels associated with each atomic system determines the various processes related to light- matter interactions. It is necessary to understand the influence of different levels in a given atomic system. In this work we focus on multi- level atomic schemes with the application of magnetic field. We analyze the different EIT windows which appears in the presence of moderately high magnetic field (∼ 10 G) strength.

Using spatial uncertainty to manipulate the size of the attention focus.

PubMed

Huang, Dan; Xue, Linyan; Wang, Xin; Chen, Yao

2016-09-01

Preferentially processing behaviorally relevant information is vital for primate survival. In visuospatial attention studies, manipulating the spatial extent of attention focus is an important question. Although many studies have claimed to successfully adjust attention field size by either varying the uncertainty about the target location (spatial uncertainty) or adjusting the size of the cue orienting the attention focus, no systematic studies have assessed and compared the effectiveness of these methods. We used a multiple cue paradigm with 2.5° and 7.5° rings centered around a target position to measure the cue size effect, while the spatial uncertainty levels were manipulated by changing the number of cueing positions. We found that spatial uncertainty had a significant impact on reaction time during target detection, while the cue size effect was less robust. We also carefully varied the spatial scope of potential target locations within a small or large region and found that this amount of variation in spatial uncertainty can also significantly influence target detection speed. Our results indicate that adjusting spatial uncertainty is more effective than varying cue size when manipulating attention field size.

Social neuroscience and its potential contribution to psychiatry

PubMed Central

Cacioppo, John T; Cacioppo, Stephanie; Dulawa, Stephanie; Palmer, Abraham A

2014-01-01

Most mental disorders involve disruptions of normal social behavior. Social neuroscience is an interdisciplinary field devoted to understanding the biological systems underlying social processes and behavior, and the influence of the social environment on biological processes, health and well-being. Research in this field has grown dramatically in recent years. Active areas of research include brain imaging studies in normal children and adults, animal models of social behavior, studies of stroke patients, imaging studies of psychiatric patients, and research on social determinants of peripheral neural, neuroendocrine and immunological processes. Although research in these areas is proceeding along largely independent trajectories, there is increasing evidence for connections across these trajectories. We focus here on the progress and potential of social neuroscience in psychiatry, including illustrative evidence for a rapid growth of neuroimaging and genetic studies of mental disorders. We also argue that neuroimaging and genetic research focused on specific component processes underlying social living is needed. PMID:24890058

Learning for All: The Value of Field Experience in Training a New Generation of Program Evaluators

ERIC Educational Resources Information Center

Buitrag, Carolina

2015-01-01

Professionals in various fields have the opportunity to train in real-life situations before they take on a job by themselves. In program evaluation, however, preservice training usually focuses on coursework oriented to research design and methods. After completing these studies, evaluators go off to conduct evaluations guided primarily by their…

An Integrated Interdisciplinary Faculty-Student Learning Community Focused on Water Issues: A Case Study

ERIC Educational Resources Information Center

Willermet, Cathy; Drake, Eron; Mueller, Anja; Juris, Stephen J.; Chhetri, Pratik; Upadhaya, Samik

2014-01-01

In response to a request from a campus student organization, faculty from three fields came together to develop and teach an integrated interdisciplinary course on water issues and social activism. This course, "Water as Life, Death, and Power," brought together topics from the fields of anthropology, biology and chemistry to explore…

Sending Farmers Back to School: The Impact of Farmer Field Schools in Indonesia. World Bank Policy Research Working Paper.

ERIC Educational Resources Information Center

Feder, Gershon; Murgai, Rinku; Quizon, Jaime B.

A study evaluated the impact of Farmer Field Schools in Indonesia, an intensive participatory training program emphasizing integrated pest management. Focus was on whether program participation improved yields and reduced pesticide use among graduates and neighbors who gained knowledge through informal communications. It used a modified…

Communication Education and Instructional Communication: Genesis and Evolution as Fields of Inquiry

ERIC Educational Resources Information Center

Morreale, Sherwyn; Backlund, Philip; Sparks, Leyla

2014-01-01

Communication education is concerned with the communicative aspects of teaching and learning in various situations and contexts. Although the historical roots of this area of inquiry date back to the classical study of rhetoric by the Greeks and Romans, this report focuses on the field's emergence as an important area of modern scholarly…

University Students' Conceptions of the Electric and Magnetic Fields and Their Interrelationships

ERIC Educational Resources Information Center

Kesonen, M. H. P.; Asikainen, M. A.; Hirvonen, P. E.

2011-01-01

This study focuses on students' conceptions of electric and magnetic fields at university level and of the interrelations between them. A total of 33 students participated in a paper and pencil test after the completion of first-year electricity and second-year electromagnetism courses. The conceptions were investigated in the contexts of a…

Research on the Field of Education Policy: Exploring Different Levels of Approach and Abstraction

ERIC Educational Resources Information Center

Mainardes, Jefferson; Tello, César

2016-01-01

This paper, of theoretical nature, explores the levels of approach and abstraction of research in the field of education policy: description, analysis and understanding. Such categories were developed based on concepts of Bourdieu's theory and on the grounds of epistemological studies focused on education policy and meta-research. This paper…

Getting "Tillerized": Traits and Outcomes of Students in a Rural Community Field Placement

ERIC Educational Resources Information Center

Averett, Paige; Carawan, Lena; Burroughs, Courtney

2012-01-01

This qualitative study sought to reveal the traits and outcomes of students who completed a rural community organizing field placement. All stakeholders involved in the placement of students took part in a focus group and follow-up individual interviews. Findings suggest that students need to be open, flexible, self-directed, and maverick in…

Through Their Eyes: Tracking the Gaze of Students in a Geology Field Course

ERIC Educational Resources Information Center

Maltese, Adam V.; Balliet, Russell N.; Riggs, Eric M.

2013-01-01

The focus of this research was to investigate how students learn to do fieldwork through observation. This study addressed the following questions: (1) Can mobile eye-tracking devices provide a robust source of data to investigate the observations and workflow of novice students while participating in a field exercise? If so, what are the…

Ethnography for Teachers' Professional Development: Japanese Approach of Investigation on Classroom Activities

ERIC Educational Resources Information Center

Matoba, Masami; Sarkar Arani Mohammed Reza

2006-01-01

In this paper, we examine how journal and ethnography field notes in Jugyou Kenkyu (lesson study) help teachers to understand the diverse range of talents and abilities of their students. Especially, we focus on how ethnography field note and reflective papers (karate) help teachers to change their assumptions about student learning. The data…

Propagation characteristics of a focused laser beam in a strontium barium niobate photorefractive crystal under reverse external electric field.

PubMed

Guo, Q L; Liang, B L; Wang, Y; Deng, G Y; Jiang, Y H; Zhang, S H; Fu, G S; Simmonds, P J

2014-10-01

The propagation characteristics of a focused laser beam in a SBN:75 photorefractive crystal strongly depend on the signal-to-background intensity ratio (R=I_s/I_b) under reverse external electric field. In the range 20>R>0.05, the laser beam shows enhanced self-defocusing behavior with increasing external electric field, while it shows self-focusing in the range 0.03>R>0.01. Spatial solitons are observed under a suitable reverse external electric field for R=0.025. A theoretical model is proposed to explain the experimental observations, which suggest a new type of soliton formation due to "enhancement" not "screening" of the external electrical field.

A general-purpose computer program for studying ultrasonic beam patterns generated with acoustic lenses

NASA Technical Reports Server (NTRS)

Roberti, Dino; Ludwig, Reinhold; Looft, Fred J.

1988-01-01

A 3-D computer model of a piston radiator with lenses for focusing and defocusing is presented. To achieve high-resolution imaging, the frequency of the transmitted and received ultrasound must be as high as 10 MHz. Current ultrasonic transducers produce an extremely narrow beam at these high frequencies and thus are not appropriate for imaging schemes such as synthetic-aperture focus techniques (SAFT). Consequently, a numerical analysis program has been developed to determine field intensity patterns that are radiated from ultrasonic transducers with lenses. Lens shapes are described and the field intensities are numerically predicted and compared with experimental results.

High Field Small Animal Magnetic Resonance Oncology Studies

PubMed Central

Bokacheva, Louisa; Ackerstaff, Ellen; LeKaye, H. Carl; Zakian, Kristen; Koutcher, Jason A.

2014-01-01

This review focuses on the applications of high magnetic field magnetic resonance imaging (MRI) and spectroscopy (MRS) to cancer studies in small animals. High field MRI can provide information about tumor physiology, the microenvironment, metabolism, vascularity and cellularity. Such studies are invaluable for understanding tumor growth and proliferation, response to treatment and drug development. The MR techniques reviewed here include 1H, 31P, Chemical Exchange Saturation Transfer (CEST) imaging, and hyperpolarized 13C MR spectroscopy as well as diffusion-weighted, Blood Oxygen Level Dependent (BOLD) contrast imaging, and dynamic contrast-enhanced MR imaging. These methods have been proven effective in animal studies and are highly relevant to human clinical studies. PMID:24374985

Direct observation of light focusing by single photoreceptor cell nuclei.

PubMed

Błaszczak, Zuzanna; Kreysing, Moritz; Guck, Jochen

2014-05-05

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

Can light-field photography ease focusing on the scalp and oral cavity?

PubMed

Taheri, Arash; Feldman, Steven R

2013-08-01

Capturing a well-focused image using an autofocus camera can be difficult in oral cavity and on a hairy scalp. Light-field digital cameras capture data regarding the color, intensity, and direction of rays of light. Having information regarding direction of rays of light, computer software can be used to focus on different subjects in the field after the image data have been captured. A light-field camera was used to capture the images of the scalp and oral cavity. The related computer software was used to focus on scalp or different parts of oral cavity. The final pictures were compared with pictures taken with conventional, compact, digital cameras. The camera worked well for oral cavity. It also captured the pictures of scalp easily; however, we had to repeat clicking between the hairs on different points to choose the scalp for focusing. A major drawback of the system was the resolution of the resulting pictures that was lower than conventional digital cameras. Light-field digital cameras are fast and easy to use. They can capture more information on the full depth of field compared with conventional cameras. However, the resolution of the pictures is relatively low. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Defect detection around rebars in concrete using focused ultrasound and reverse time migration.

PubMed

Beniwal, Surendra; Ganguli, Abhijit

2015-09-01

Experimental and numerical investigations have been performed to assess the feasibility of damage detection around rebars in concrete using focused ultrasound and a Reverse Time Migration (RTM) based subsurface imaging algorithm. Since concrete is heterogeneous, an unfocused ultrasonic field will be randomly scattered by the aggregates, thereby masking information about damage(s). A focused ultrasonic field, on the other hand, increases the possibility of detection of an anomaly due to enhanced amplitude of the incident field in the focal region. Further, the RTM based reconstruction using scattered focused field data is capable of creating clear images of the inspected region of interest. Since scattering of a focused field by a damaged rebar differs qualitatively from that of an undamaged rebar, distinct images of damaged and undamaged situations are obtained in the RTM generated images. This is demonstrated with both numerical and experimental investigations. The total scattered field, acquired on the surface of the concrete medium, is used as input for the RTM algorithm to generate the subsurface image that helps to identify the damage. The proposed technique, therefore, has some advantage since knowledge about the undamaged scenario for the concrete medium is not necessary to assess its integrity. Copyright © 2015 Elsevier B.V. All rights reserved.

Narrative research in psychotherapy: a critical review.

PubMed

Avdi, Evrinomy; Georgaca, Eugenie

2007-09-01

This paper is a review of studies which utilise the notion of narrative to analyse psychotherapy. Its purpose is to systematically present this diverse field of research, to highlight common themes and divergences between different strands and to further the development and integration of narrative research in psychotherapy. The paper reviews studies which employ an applied textual analysis of narratives produced in the context of psychotherapy. Criteria for inclusion of studies are, firstly, the analysis of therapeutic and therapy-related texts and, secondly, the adoption of a narrative psychological perspective. The studies were examined on the basis of the notion of narrative they employ and the aspects of client narratives they focus on, and were grouped accordingly in the review. The majority of the studies reviewed assume a constructivist approach to narrative, adopt a representational view of language, focus primarily on client micro-narratives and relate to cognitive-constructivist and process-experiential psychotherapeutic approaches. A smaller group of studies assume a social constructionist approach to narrative and a functional view of language, focus on micro-narratives, highlight the interactional and wider social aspects of narrative and relate to postmodern trends in psychotherapy. The range of conceptualisations of narrative in the studies reviewed, from a representational psychological view to a constructionist social view, reflects tensions within narrative psychology itself. Moreover, two trends can be discerned in the field reviewed, narrative analysis of therapy, which draws from narrative theory and utilises the analytic approaches of narrative research to study psychotherapy, and analyses of narrative in therapy, which study client narratives using non-narrative qualitative methods. Finally, the paper highlights the need for integration of this diverse field of research and urges for the development of narrative studies of psychotherapy which employ a broader social understanding of narrative production and transformation.

Performance of high power S-band klystrons focused with permanent magnet

NASA Astrophysics Data System (ADS)

Fukuda, S.; Shidara, T.; Saito, Y.; Hanaki, H.; Nakao, K.; Homma, H.; Anami, S.; Tanaka, J.

1987-02-01

Performance of high power S-band klystrons focused with permanent magnet is presented. The axial magnetic field distribution and the transverse magnetic field play an important role in the tube performance. Effects of the reversal field in the collector and the cathode-anode region are discussed precisely. It is also shown that the tube efficiency is strongly affected with the residual transverse magnetic field. The allowable transverse field is less than 0.3 percent of the longitudinal field in the entire RF interaction region of the klystron.

Unboxing the Black Box of Visual Expertise in Medicine

ERIC Educational Resources Information Center

Jarodzka, Halszka; Boshuizen, Henny P. .

2017-01-01

Visual expertise in medicine has been a subject of research since many decades. Interestingly, it has been investigated from two little related fields, namely the field that focused mainly on the visual search aspects whilst ignoring higher-level cognitive processes involved in medical expertise, and the field that mainly focused on these…

Beam trapping in high-current cyclic accelerators with strong-focusing fields. Memorandum report, January-December 1984

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

Sprangle, P.; Kapetanakos, C.A.

1985-03-06

In cyclic induction accelerators, the energy of the particles increases slowly in synchronism with the vertical (betatron) magnetic field. As a consequence of the slow acceleration, the charged particles must be confined by the weak-focusing magnetic field over long periods of time, and thus field errors, instabilities, and radiation losses can impose limitations on the acceleration process. These limitations can be substantially relaxed if the acceleration were to occur rapidly, say over a few microseconds. An appropriate name for such an accelerator is REBA-TRON (Rapid Electron Beam Accelerator). This paper considers a possible mechanism which could trap a high currentmore » electron beam in the strong focusing magnetic fields of the rebatron. We investigate a possible mechanism for trapping an intense relativistic electron beam confined by strong focusing fields. In our model the electron beam is assumed to be injected into torsatron fields off axis, near the chamber walls. The finite resistivity of the walls results in a drag force on the beam centroid which may cause the beam to spiral inward towards the axis of the chamber. We have analyzed this mechanism and obtained decay rates for the inward spiraling beam motion.« less

The Effect of Focus on Form and Task Complexity on L2 Learners' Oral Task Performance

ERIC Educational Resources Information Center

Salimi, Asghar

2015-01-01

Second Language learners' oral task performance has been one of interesting and research generating areas of investigations in the field of second language acquisition specially, task-based language teaching and learning. The main purpose of the present study is to investigate the effect of focus on form and task complexity on L2 learners' oral…

An Investigation of Science, Technology, Engineering and Mathematics (STEM) Focused High Schools in the U.S.

ERIC Educational Resources Information Center

Scott, Catherine

2012-01-01

This study examined the characteristics of 10 science, technology, engineering and mathematics (STEM) focused high schools that were selected from various regions across the United States. In an effort to better prepare students for careers in STEM fields, many schools have been designed and are currently operational, while even more are in the…

"You See the Whole Tree, Not Just the Stump:" Religious Fundamentalism, Capital and Public Schooling

ERIC Educational Resources Information Center

Minikel-Lacocque, Julie

2015-01-01

This article draws on data from a larger collective case study which focused on the transition to college for Latino/a students at a prestigious, public, predominantly White institution. Here, I focus on one student and analyze interview and field note data to examine this transition for Jasmine, a fundamentalist Christian who identifies as a…

How Are Learning Strategies Reflected in the Eyes? Combining Results from Self-Reports and Eye-Tracking

ERIC Educational Resources Information Center

Catrysse, Leen; Gijbels, David; Donche, Vincent; De Maeyer, Sven; Lesterhuis, Marije; Van den Bossche, Piet

2018-01-01

Background: Up until now, empirical studies in the Student Approaches to Learning field have mainly been focused on the use of self-report instruments, such as interviews and questionnaires, to uncover differences in students' general preferences towards learning strategies, but have focused less on the use of task-specific and online measures.…

Teachers' Understanding of Multicultural Education and the Correlates of Multicultural Content Integration in Flanders

ERIC Educational Resources Information Center

Agirdag, Orhan; Merry, Michael S.; Van Houtte, Mieke

2016-01-01

The bulk of scholarship on multicultural education continues to focus exclusively on U.S. education. Previous studies published in this field also have focused largely on topics that are considered relevant for the United States, whereas little attention has been paid to topics that are less problematized in the United States. In this mixed-method…

The Joy of Social Work Administration: An Exploratory Qualitative Study of Human Service Administrators' Positive Perceptions of Their Work

ERIC Educational Resources Information Center

Watson, Larry D.; Hoefer, Richard A.

2016-01-01

Positive organizational psychology suggests that researchers should focus on the rewarding elements of work life, yet those in the fields of social work and nonprofit administration have not conducted research in line with this admonition. Indeed, the current focus on administrative challenges and problems may be part of the reason there is…

Nanoporous Metals with Structural Hierarchy: A Review

DOE PAGES

Juarez, Theresa; Biener, Juergen; Weissmüller, Jörg; ...

2017-08-09

Nanoporous (np) metals have generated much interest since they combine several desirable material characteristics, such as high surface area, mechanical size effects, and high conductivity. Most of the research has been focused on np Au due to its relatively straightforward synthesis, chemical stability, and many promising applications in the fields of catalysis and actuation. Other materials, such as np-Cu, Ag, and Pd have also been studied. Here, this review discusses recent advances in the field of np metals, focusing on new research areas that implement and leverage structural hierarchy while using np metals as their base structural constituents. First, wemore » focus on single-element porous metals that are made of np metals at the fundamental level, but synthesized with additional levels of porosity. Second, we discuss the fabrication of composite structures, which use auxiliary materials to enhance the properties of np metals. Important applications of these hierarchical materials, especially in the fields of catalysis and electrochemistry, are also reviewed. Lastly, we conclude with a discussion about future opportunities for the advancement and application of np metals.« less

Nanoporous Metals with Structural Hierarchy: A Review

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

Juarez, Theresa; Biener, Juergen; Weissmüller, Jörg

Nanoporous (np) metals have generated much interest since they combine several desirable material characteristics, such as high surface area, mechanical size effects, and high conductivity. Most of the research has been focused on np Au due to its relatively straightforward synthesis, chemical stability, and many promising applications in the fields of catalysis and actuation. Other materials, such as np-Cu, Ag, and Pd have also been studied. Here, this review discusses recent advances in the field of np metals, focusing on new research areas that implement and leverage structural hierarchy while using np metals as their base structural constituents. First, wemore » focus on single-element porous metals that are made of np metals at the fundamental level, but synthesized with additional levels of porosity. Second, we discuss the fabrication of composite structures, which use auxiliary materials to enhance the properties of np metals. Important applications of these hierarchical materials, especially in the fields of catalysis and electrochemistry, are also reviewed. Lastly, we conclude with a discussion about future opportunities for the advancement and application of np metals.« less

Synthesis of focused beam with controllable arbitrary homogeneous polarization using engineered vectorial optical fields.

PubMed

Rui, Guanghao; Chen, Jian; Wang, Xiaoyan; Gu, Bing; Cui, Yiping; Zhan, Qiwen

2016-10-17

The propagation and focusing properties of light beams continue to remain a research interest owning to their promising applications in physics, chemistry and biological sciences. One of the main challenges to these applications is the control of polarization distribution within the focal volume. In this work, we propose and experimentally demonstrate a method for generating a focused beam with arbitrary homogeneous polarization at any transverse plane. The required input field at the pupil plane of a high numerical aperture objective lens can be found analytically by solving an inverse problem with the Richard-Wolf vectorial diffraction method, and can be experimentally created with a vectorial optical field generator. Focused fields with various polarizations are successfully generated and verified using a Stokes parameter measurement to demonstrate the capability and versatility of proposed technique.

Chronic Traumatic Encephalopathy

MedlinePlus

... trauma is likely the cause of CTE. Football players have been the focus of most CTE studies. However, athletes participating in other sports, including soccer, ice hockey, rugby, boxing, wrestling, basketball, field hockey, ...

The Impact of an Informal Science Program on Students' Science Knowledge and Interest

NASA Astrophysics Data System (ADS)

Zandstra, Anne Maria

In this sequential explanatory mixed methods study, quantitative and qualitative data were used to measure the impact of an informal science program on eleventh grade students' science knowledge and interest. The local GEAR UP project has been working for six years with a cohort of students who were in eleventh and twelfth grade during the time of the study. Participants of this study were 122 eleventh grade students from this cohort. In the first, quantitative phase, state standardized test scores and a modified version of the Test of Science Related Attitudes (TOSRA) were used to measure participants' science knowledge and interest respectively. The findings of the quantitative phase revealed a small but significant correlation between students' attendance at the program elements (in total number of hours) and their science knowledge. In addition, small but significant correlations were found between (1) students' attendance at the mathematics program element and their total interest scores, (2) their mathematics attendance and the career interest subscore, and (3) their total attendance and the normality of scientist subscore. The qualitative data in the second phase consisted of focus group interviews with fourteen of the participants. Results of this phase showed that the majority of the focus group participants agreed that they had learned something from the GEAR UP field trips and half of them thought the field trips had impacted their grades and test scores. Furthermore, a majority of the focus group participants concurred that their experiences in the field trips had increased their interest in science. The purpose of the qualitative phase of this study was to provide explanations for the results of the quantitative phase. Explanations for the correlation between attendance and knowledge were that the field trips covered the same content as the formal science classes and that students learned more because they perceived the field trips as fun and hands-on. The correlations between attendance and interest were explained by the fact that students had the opportunity to see interesting aspects of science and interact with real scientists during the field trips.

Optical fiber plasmonic lens for near-field focusing fabricated through focused ion beam

NASA Astrophysics Data System (ADS)

Sloyan, Karen; Melkonyan, Henrik; Moreira, Paulo; Dahlem, Marcus S.

2017-02-01

We report on numerical simulations and fabrication of an optical fiber plasmonic lens for near-field focusing applications. The plasmonic lens consists of an Archimedean spiral structure etched through a 100 nm-thick Au layer on the tip of a single-mode SM600 optical fiber operating at a wavelength of 632:8 nm. Three-dimensional finite-difference time-domain computations show that the relative electric field intensity of the focused spot increases 2:1 times when the number of turns increases from 2 to 12. Furthermore, a reduction of the intensity is observed when the initial inner radius is increased. The optimized plasmonic lens focuses light into a spot with a full-width at half-maximum of 182 nm, beyond the diffraction limit. The lens was fabricated by focused ion beam milling, with a 200nm slit width.

An improved large-field focusing schlieren system

NASA Technical Reports Server (NTRS)

Weinstein, Leonard M.

1991-01-01

The analysis and performance of a high-brightness large-field focusing schlieren system is described. The system can be used to examine complex two- and three-dimensional flows. Techniques are described to obtain focusing schlieren through distorting optical elements, to use multiple colors in a time multiplexing technique, and to use diffuse screen holography for three-dimensional photographs.

Perpendicular Diffusion Coefficient of Comic Rays: The Presence of Weak Adiabatic Focusing

NASA Astrophysics Data System (ADS)

Wang, J. F.; Qin, G.; Ma, Q. M.; Song, T.; Yuan, S. B.

2017-08-01

The influence of adiabatic focusing on particle diffusion is an important topic in astrophysics and plasma physics. In the past, several authors have explored the influence of along-field adiabatic focusing on the parallel diffusion of charged energetic particles. In this paper, using the unified nonlinear transport theory developed by Shalchi and the method of He and Schlickeiser, we derive a new nonlinear perpendicular diffusion coefficient for a non-uniform background magnetic field. This formula demonstrates that the particle perpendicular diffusion coefficient is modified by along-field adiabatic focusing. For isotropic pitch-angle scattering and the weak adiabatic focusing limit, the derived perpendicular diffusion coefficient is independent of the sign of adiabatic focusing characteristic length. For the two-component model, we simplify the perpendicular diffusion coefficient up to the second order of the power series of the adiabatic focusing characteristic quantity. We find that the first-order modifying factor is equal to zero and that the sign of the second order is determined by the energy of the particles.

Focusing a fountain of neutral cesium atoms with an electrostatic lens triplet

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

Kalnins, Juris G.; Amini, Jason M.; Gould, Harvey

2005-10-15

An electrostatic lens with three focusing elements in an alternating-gradient configuration is used to focus a fountain of cesium atoms in their ground (strong-field-seeking) state. The lens electrodes are shaped to produce only sextupole plus dipole equipotentials which avoids adding the unnecessary nonlinear forces present in cylindrical lenses. Defocusing between lenses is greatly reduced by having all of the main electric fields point in the same direction and be of nearly equal magnitude. The addition of the third lens gave us better control of the focusing strength in the two transverse planes and allowed focusing of the beam to halfmore » the image size in both planes. The beam envelope was calculated for lens voltages selected to produced specific focusing properties. The calculations, starting from first principles, were compared with measured beam sizes and found to be in good agreement. Application to fountain experiments, atomic clocks, and focusing polar molecules in strong-field-seeking states is discussed.« less

Qualitative Study of a Solution-Focused Training Program for Taiwanese Military Instructors.

PubMed

Pan, Peter Jen Der; Deng, Liang-Yu F; Tsia, Shio-Ling; Jiang, Jye-Ru Karen; Wang, Yu Jen

2016-04-01

This study explored Taiwanese military instructors' perceptions of a training program using a solution-focused approach and its initial application to students with behavior problems. A total of 25 military instructors (16 men, 9 women; M age = 38.6 years, SD = 5.8) and 10 students (three men, seven women; M age = 17.5 years, SD = 0.9) participated in the study through convenience sampling. Grounded theory method was adopted for data analysis. Six prominent categories emerged from the focus group interview, weekly training notes, and the researcher's field notes, including reactions to learning solution-focused approach, strengths and weaknesses of using the solution-focused approach, identification of military instructors role function, initial responses to the techniques of the solution-focused approach, a positive attitude to deal with students' problems, and from assimilation to transformation. In addition, feedback collected from students was grouped into a seventh category. Finally, a modified pattern was developed for military instructors to use when working with students. © The Author(s) 2016.

A review of models for near-field exposure pathways of chemicals in consumer products.

PubMed

Huang, Lei; Ernstoff, Alexi; Fantke, Peter; Csiszar, Susan A; Jolliet, Olivier

2017-01-01

Exposure to chemicals in consumer products has been gaining increasing attention, with multiple studies showing that near-field exposures from products is high compared to far-field exposures. Regarding the numerous chemical-product combinations, there is a need for an overarching review of models able to quantify the multiple transfers of chemicals from products used near-field to humans. The present review therefore aims at an in-depth overview of modeling approaches for near-field chemical release and human exposure pathways associated with consumer products. It focuses on lower-tier, mechanistic models suitable for life cycle assessments (LCA), chemical alternative assessment (CAA) and high-throughput screening risk assessment (HTS). Chemicals in a product enter the near-field via a defined "compartment of entry", are transformed or transferred to adjacent compartments, and eventually end in a "human receptor compartment". We first focus on models of physical mass transfers from the product to 'near-field' compartments. For transfers of chemicals from article interior, adequate modeling of in-article diffusion and of partitioning between article surface and air/skin/food is key. Modeling volatilization and subsequent transfer to the outdoor is crucial for transfers of chemicals used in the inner space of appliances, on object surfaces or directly emitted to indoor air. For transfers from skin surface, models need to reflect the competition between dermal permeation, volatilization and fraction washed-off. We then focus on transfers from the 'near-field' to 'human' compartments, defined as respiratory tract, gastrointestinal tract and epidermis, for which good estimates of air concentrations, non-dietary ingestion parameters and skin permeation are essential, respectively. We critically characterize for each exposure pathway the ability of models to estimate near-field transfers and to best inform LCA, CAA and HTS, summarizing the main characteristics of the potentially best-suited models. This review identifies large knowledge gaps for several near-field pathways and suggests research needs and future directions. Copyright © 2016 Elsevier B.V. All rights reserved.

Advances in Neutron Spectroscopy and High Magnetic Field Instrumentation for studies of Correlated Electron Systems

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

Granroth, Garrett E

2011-01-01

Neutron Spectroscopy has provided critical information on the magnetism in correlated electron systems. Specifically quantum magnets, superconductors, and multi-ferroics are areas of productive research. A discussion of recent measurements on the SEQUOIA spectrometer will provide examples of how novel instrumentation concepts are used on the latest generation of spectrometers to extend our knowledge in such systems. The now ubiquitous function of sample rotation allows for full mapping of volumes ofmore » $Q$ and $$\\omega$$ space. An instrument focused on low angles could extend these maps to cover more of the first Brillioun zone. Innovative chopper cascades allow two unique modes of operation. Multiplexed measurements allow the simultaneous measurement of high and low energy features in an excitation spectrum. Alternatively by limiting the neutron bandwidth incident on the Fermi Chopper, background from subsequent time frames is removed, enabling the observation of weak, large energy transfer features. Finally the implementation of event-based detection for neutron experiments is time correlated experiments. Diffraction studies of the high field spin states in MnWO$$_4$$ using magnetic fields up to 30 T, provided by a pulsed magnet, illustrate this method. Expanding the high field studies to spectroscopy will require a novel instrument, focused around a world class DC magnet, like Zeemans proposed for the SNS.« less

Ion collection from a plasma by a pinhole

NASA Technical Reports Server (NTRS)

Snyder, David B.; Herr, Joel L.

1992-01-01

Ion focusing by a biased pinhole is studied numerically. Laplace's equation is solved in 3-D for cylindrical symmetry on a constant grid to determine the potential field produced by a biased pinhole in a dielectric material. Focusing factors are studied for ions of uniform incident velocity with a 3-D Maxwellian distribution superimposed. Ion currents to the pinhole are found by particle tracking. The focusing factor of positive ions as a function of initial velocity, temperature, injection radius, and hole size is reported. For a typical Space Station Freedom environment (oxygen ions having a 4.5 eV ram energy, 0.1 eV temperature, and a -140 V biased pinhole), a focusing factor of 13.35 is found for a 1.5 mm radius pinhole.

Measurement and numerical simulation of high intensity focused ultrasound field in water

NASA Astrophysics Data System (ADS)

Lee, Kang Il

2017-11-01

In the present study, the acoustic field of a high intensity focused ultrasound (HIFU) transducer in water was measured by using a commercially available needle hydrophone intended for HIFU use. To validate the results of hydrophone measurements, numerical simulations of HIFU fields were performed by integrating the axisymmetric Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation from the frequency-domain perspective with the help of a MATLAB-based software package developed for HIFU simulation. Quantitative values for the focal waveforms, the peak pressures, and the size of the focal spot were obtained in various regimes of linear, quasilinear, and nonlinear propagation up to the source pressure levels when the shock front was formed in the waveform. The numerical results with the HIFU simulator solving the KZK equation were compared with the experimental data and found to be in good agreement. This confirms that the numerical simulation based on the KZK equation is capable of capturing the nonlinear pressure field of therapeutic HIFU transducers well enough to make it suitable for HIFU treatment planning.

High magnetic field behavior of NbFe2

NASA Astrophysics Data System (ADS)

Rauch, D.; Steinki, N.; Knafo, W.; Pfleiderer, C.; Duncan, W. J.; Grosche, F. M.; Süllow, S.

2018-05-01

We have carried out a high magnetic field study on single crystalline stoichiometric NbFe2, a material discussed in terms quantum criticality in itinerant ferromagnets, by means of high field resistivity experiments. Our experiments have been performed at the Laboratoire National des Champs Magnétiques Intenses in Toulouse, France. The resistivity of single crystalline NbFe2, has been investigated in external fields up to 15.5 T aligned along the c-axis in the temperature range of 1.4-55 K. The main focus of our study lies on the method to extract TN from the magnetoresistivity measurements, because TN could not be easily observed in temperature dependent resistivity for stoichiometric NbFe2.

Terrestrial Ecology Guide.

ERIC Educational Resources Information Center

Morrison, James W., Ed.; Hall, James A., Ed.

This collection of study units focuses on the study of the ecology of land habitats. Considered are such topics as map reading, field techniques, forest ecosystem, birds, insects, small mammals, soils, plant ecology, preparation of terrariums, air pollution, photography, and essentials of an environmental studies program. Each unit contains…

Intravital microscopy: a novel tool to study cell biology in living animals.

PubMed

Weigert, Roberto; Sramkova, Monika; Parente, Laura; Amornphimoltham, Panomwat; Masedunskas, Andrius

2010-05-01

Intravital microscopy encompasses various optical microscopy techniques aimed at visualizing biological processes in live animals. In the last decade, the development of non-linear optical microscopy resulted in an enormous increase of in vivo studies, which have addressed key biological questions in fields such as neurobiology, immunology and tumor biology. Recently, few studies have shown that subcellular processes can be imaged dynamically in the live animal at a resolution comparable to that achieved in cell cultures, providing new opportunities to study cell biology under physiological conditions. The overall aim of this review is to give the reader a general idea of the potential applications of intravital microscopy with a particular emphasis on subcellular imaging. An overview of some of the most exciting studies in this field will be presented using resolution as a main organizing criterion. Indeed, first we will focus on those studies in which organs were imaged at the tissue level, then on those focusing on single cells imaging, and finally on those imaging subcellular organelles and structures.

A novel approach for in vitro studies applying electrical fields to cell cultures by transformer-like coupling.

PubMed

Hess, R; Neubert, H; Seifert, A; Bierbaum, S; Hart, D A; Scharnweber, D

2012-12-01

The purpose of this study was to develop a new apparatus for in vitro studies applying low frequency electrical fields to cells without interfering side effects like biochemical reactions or magnetic fields which occur in currently available systems. We developed a non-invasive method by means of the principle of transformer-like coupling where the magnetic field is concentrated in a toroid and, therefore, does not affect the cell culture. Next to an extensive characterization of the electrical field parameters, initial cell culture studies have focused on examining the response of bone marrow-derived human mesenchymal stem cells (MSCs) to pulsed electrical fields. While no significant differences in the proliferation of human MSCs could be detected, significant increases in ALP activity as well as in gene expression of other osteogenic markers were observed. The results indicate that transformer-like coupled electrical fields can be used to influence osteogenic differentiation of human MSCs in vitro and can pose a useful tool in understanding the influence of electrical fields on the cellular and molecular level.

Design considerations for a computer controlled multileaf collimator for the Harper Hospital fast neutron therapy facility.

PubMed

Maughan, Richard L; Yudelev, Mark; Aref, Amr; Chuba, Paul J; Forman, Jeffrey; Blosser, Emanuel J; Horste, Timothy

2002-04-01

The d(48.5) + Be neutron beam from the Harper Hospital superconducting cyclotron is collimated using a unique multirod collimator (MRC). A computer controlled multileaf collimator (MLC) is being designed to improve efficiency and allow for the future development of intensity modulated radiation therapy with neutrons. For the current study the use of focused or unfocused collimator leaves has been studied. Since the engineering effort associated with the leaf design and materials choice impacts significantly on cost, it was desirable to determine the clinical impact of using unfocused leaves in the MLC design. The MRC is a useful tool for studying the effects of using focused versus unfocused beams on beam penumbra. The effects of the penumbra for the different leaf designs on tumor and normal tissue DVHs in two selected sites (prostate and head and neck) was investigated. The increase in the penumbra resulting from using unfocused beams was small (approximately 1.5 mm for a 5 x 5 cm2 field and approximately 7.6 mm for a 25 x 25 cm2 field at 10 cm depth) compared to the contribution of phantom scatter to the penumbra width (5.4 and 20 mm for the small and large fields at 10 cm depth, respectively). Comparison of DVHs for tumor and critical normal tissue in a prostate and head and neck case showed that the dosimetric disadvantages of using an unfocused rather than focused beam were minimal and only significant at shallow depths. For the rare cases, where optimum penumbra conditions are required, a MLC incorporating tapered leaves and, thus, providing focused collimation in one plane is necessary.

Nonparaxial propagation and focusing properties of azimuthal-variant vector fields diffracted by an annular aperture.

PubMed

Gu, Bing; Xu, Danfeng; Pan, Yang; Cui, Yiping

2014-07-01

Based on the vectorial Rayleigh-Sommerfeld integrals, the analytical expressions for azimuthal-variant vector fields diffracted by an annular aperture are presented. This helps us to investigate the propagation behaviors and the focusing properties of apertured azimuthal-variant vector fields under nonparaxial and paraxial approximations. The diffraction by a circular aperture, a circular disk, or propagation in free space can be treated as special cases of this general result. Simulation results show that the transverse intensity, longitudinal intensity, and far-field divergence angle of nonparaxially apertured azimuthal-variant vector fields depend strongly on the azimuthal index, the outer truncation parameter and the inner truncation parameter of the annular aperture, as well as the ratio of the waist width to the wavelength. Moreover, the multiple-ring-structured intensity pattern of the focused azimuthal-variant vector field, which originates from the diffraction effect caused by an annular aperture, is experimentally demonstrated.

Generation of a sub-half-wavelength focal spot with purely transverse spin angular momentum

NASA Astrophysics Data System (ADS)

Hang, Li; Fu, Jian; Yu, Xiaochang; Wang, Ying; Chen, Peifeng

2017-11-01

We theoretically demonstrate that optical focus fields with purely transverse spin angular momentum (SAM) can be obtained when a kind of special incident fields is focused by a high numerical aperture (NA) aplanatic lens (AL). When the incident pupil fields are refracted by an AL, two transverse Cartesian components of the electric fields at the exit pupil plane do not have the same order of sinusoidal or cosinoidal components, resulting in zero longitudinal SAMs of the focal fields. An incident field satisfying above conditions is then proposed. Using the Richard-Wolf vectorial diffraction theory, the energy density and SAM density distributions of the tightly focused beam are calculated and the results clearly validate the proposed theory. In addition, a sub-half-wavelength focal spot with purely transverse SAM can be achieved and a flattop energy density distribution parallel to z-axis can be observed around the maximum energy density point.

A Missing Link in Suggestibility Research: What Is Known About the Behavior of Field Interviewers in Unstructured Interviews With Young Children?

ERIC Educational Resources Information Center

Gilstrap, Livia L.

2004-01-01

Despite suggestibility researchers' focus on adult behaviors that distort children's reports, whether behaviors examined in experimental work are used in the field is unknown. The current study presents a mutually exclusive and exhaustive hierarchical coding system that reflects interview questioning behaviors of concern in experimental work. The…

Lesson Study: A Collaborative Approach to Scholarship for Teaching and Learning in Higher Education

ERIC Educational Resources Information Center

Wood, Phil; Cajkler, Wasyl

2018-01-01

The Scholarship of Teaching and Learning has become an important field of inquiry, focusing on the development of new and critical pedagogic approaches in higher education. It is a broad field leading to the emergence of a number of contrasting perspectives concerning the development of insights into teaching and learning. In this article, we…

Motion of a Charged Particle in a Constant and Uniform Electromagnetic Field

ERIC Educational Resources Information Center

Ladino, L. A.; Rondón, S. H.; Orduz, P.

2015-01-01

This paper focuses on the use of software developed by the authors that allows the visualization of the motion of a charged particle under the influence of magnetic and electric fields in 3D, at a level suitable for introductory physics courses. The software offers the possibility of studying a great number of physical situations that can…

The Effects of Highlight Color on Immediate Recall on Subjects of Different Cognitive Styles.

ERIC Educational Resources Information Center

Worley, Gary M.; Moore, David M.

2001-01-01

Discussion of the use of color for enhancing recognition memory focuses on a study of undergraduates that evaluated images as black and white, full color, or highlight color and the effect these characteristics had on recognition memory and recall for learners classified as field-dependent and field-independent in terms of cognitive style. (LRW)

Novel Sensor for the In Situ Measurement of Uranium Fluxes

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

Hatfield, Kirk

2015-02-10

The goal of this project was to develop a sensor that incorporates the field-tested concepts of the passive flux meter to provide direct in situ measures of flux for uranium and groundwater in porous media. Measurable contaminant fluxes [J] are essentially the product of concentration [C] and groundwater flux or specific discharge [q ]. The sensor measures [J] and [q] by changes in contaminant and tracer amounts respectively on a sorbent. By using measurement rather than inference from static parameters, the sensor can directly advance conceptual and computational models for field scale simulations. The sensor was deployed in conjunction withmore » DOE in obtaining field-scale quantification of subsurface processes affecting uranium transport (e.g., advection) and transformation (e.g., uranium attenuation) at the Rifle IFRC Site in Rifle, Colorado. Project results have expanded our current understanding of how field-scale spatial variations in fluxes of uranium, groundwater and salient electron donor/acceptors are coupled to spatial variations in measured microbial biomass/community composition, effective field-scale uranium mass balances, attenuation, and stability. The coupling between uranium, various nutrients and micro flora can be used to estimate field-scale rates of uranium attenuation and field-scale transitions in microbial communities. This research focuses on uranium (VI), but the sensor principles and design are applicable to field-scale fate and transport of other radionuclides. Laboratory studies focused on sorbent selection and calibration, along with sensor development and validation under controlled conditions. Field studies were conducted at the Rifle IFRC Site in Rifle, Colorado. These studies were closely coordinated with existing SBR (formerly ERSP) projects to complement data collection. Small field tests were conducted during the first two years that focused on evaluating field-scale deployment procedures and validating sensor performance under controlled field conditions. In the third and fourth year a suite of larger field studies were conducted. For these studies, the uranium flux sensor was used with uranium speciation measurements and molecular-biological tools to characterize microbial community and active biomass at synonymous wells distributed in a large grid. These field efforts quantified spatial changes in uranium flux and field-scale rates of uranium attenuation (ambient and stimulated), uranium stability, and quantitatively assessed how fluxes and effective reaction rates were coupled to spatial variations in microbial community and active biomass. Analyses of data from these field experiments were used to generate estimates of Monod kinetic parameters that are ‘effective’ in nature and optimal for modeling uranium fate and transport at the field-scale. This project provided the opportunity to develop the first sensor that provides direct measures of both uranium (VI) and groundwater flux. A multidisciplinary team was assembled to include two geochemists, a microbiologist, and two quantitative contaminant hydrologists. Now that the project is complete, the sensor can be deployed at DOE sites to evaluate field-scale uranium attenuation, source behavior, the efficacy of remediation, and off-site risk. Because the sensor requires no power, it can be deployed at remote sites for periods of days to months. The fundamental science derived from this project can be used to advance the development of predictive models for various transport and attenuation processes in aquifers. Proper development of these models is critical for long-term stewardship of contaminated sites in the context of predicting uranium source behavior, remediation performance, and off-site risk.« less

Volumetric bioimaging based on light field microscopy with temporal focusing illumination

NASA Astrophysics Data System (ADS)

Hsu, Feng-Chun; Sie, Yong Da; Lai, Feng-Jie; Chen, Shean-Jen

2018-02-01

Light field technique at a single shot can get the whole volume image of observed sample. Therefore, the original frame rate of the optical system can be taken as the volumetric image rate. For dynamically imaging whole micron-scale biosample, a light field microscope with temporal focusing illumination has been developed. In the light field microscope, the f-number of the microlens array (MLA) is adopted to match that of the objective; hence, the subimages via adjacent lenslets do not overlay each other. A three-dimensional (3D) deconvolution algorithm is utilized to deblur the out-of-focusing part. Conventional light field microscopy (LFM) illuminates whole volume sample even noninteresting parts; nevertheless, whole volume excitation causes even more damage on bio-sample and also increase the background noise from the out of range. Therefore, temporal focusing is integrated into the light field microscope for selecting the illumination volume. Herein, a slit on the back focal plane of the objective is utilized to control the axial excitation confinement for selecting the illumination volume. As a result, the developed light field microscope with the temporal focusing multiphoton illumination (TFMPI) can reconstruct 3D images within the selected volume, and the lateral resolution approaches to the theoretical value. Furthermore, the 3D Brownian motion of two-micron fluorescent beads is observed as the criterion of dynamic sample. With superior signal-to-noise ratio and less damage to tissue, the microscope is potential to provide volumetric imaging for vivo sample.

Comparison of Focused and Near-Field Imaging of Spray on Foam Insulation (SOFI) at Millimeter Wave Frequencies

NASA Technical Reports Server (NTRS)

Kharkovshy, S.; Zoughi, R.; Hepburn, F. L.

2007-01-01

Millimeter wave imaging techniques can provide high spatial-resolution images of various composites. Lens antennas may be incorporated into the imaging system to provide a small incident beam footprint. Another approach may involve the use of horn antennas, which if operating in their near-fields, images with reasonably high spatial-resolutions may also be obtained. This paper gives a comparison between such near-field and focused far-field imaging of the Space Shuttle Spray on Foam Insulation (SOFI) used in its external fuel tank at millimeter wave frequencies. Small horn antennas and lens antennas with relatively long depth of focus were used in this investigation.

Rehabilitation of jointed Portland cement concrete pavements : SPS-6--initial evaluation and analysis

DOT National Transportation Integrated Search

2005-10-01

The Specific Pavement Studies 6 (SPS-6) experiment, "Rehabilitation of Jointed Portland Cement Concrete Pavements," was designed as a controlled field experiment that focuses on the study of specific rehabilitation design features of jointed plain co...

Geological Fieldwork: A Study Carried out with Portuguese Secondary School Students

ERIC Educational Resources Information Center

Esteves, Helena; Ferreira, Paulo; Vasconcelos, Clara; Fernandes, Isabel

2013-01-01

Recognizing the relevance that fieldwork and field trips have in the teaching of geosciences and related learning processes, this study presents two geological fieldwork studies that were established with Portuguese secondary school students. Both studies were focused on geoscience content knowledge, and attempted to increase environmental…

Avoiding Focus Shifts in Surgical Telementoring Using an Augmented Reality Transparent Display.

PubMed

Andersen, Daniel; Popescu, Voicu; Cabrera, Maria Eugenia; Shanghavi, Aditya; Gomez, Gerardo; Marley, Sherri; Mullis, Brian; Wachs, Juan

2016-01-01

Conventional surgical telementoring systems require the trainee to shift focus away from the operating field to a nearby monitor to receive mentor guidance. This paper presents the next generation of telementoring systems. Our system, STAR (System for Telementoring with Augmented Reality) avoids focus shifts by placing mentor annotations directly into the trainee's field of view using augmented reality transparent display technology. This prototype was tested with pre-medical and medical students. Experiments were conducted where participants were asked to identify precise operating field locations communicated to them using either STAR or a conventional telementoring system. STAR was shown to improve accuracy and to reduce focus shifts. The initial STAR prototype only provides an approximate transparent display effect, without visual continuity between the display and the surrounding area. The current version of our transparent display provides visual continuity by showing the geometry and color of the operating field from the trainee's viewpoint.

Analysis of Mental Workload in Online Shopping: Are Augmented and Virtual Reality Consistent?

PubMed

Zhao, Xiaojun; Shi, Changxiu; You, Xuqun; Zong, Chenming

2017-01-01

A market research company (Nielsen) reported that consumers in the Asia-Pacific region have become the most active group in online shopping. Focusing on augmented reality (AR), which is one of three major techniques used to change the method of shopping in the future, this study used a mixed design to discuss the influences of the method of online shopping, user gender, cognitive style, product value, and sensory channel on mental workload in virtual reality (VR) and AR situations. The results showed that males' mental workloads were significantly higher than females'. For males, high-value products' mental workload was significantly higher than that of low-value products. In the VR situation, the visual mental workload of field-independent and field-dependent consumers showed a significant difference, but the difference was reduced under audio-visual conditions. In the AR situation, the visual mental workload of field-independent and field-dependent consumers showed a significant difference, but the difference increased under audio-visual conditions. This study provided a psychological study of online shopping with AR and VR technology with applications in the future. Based on the perspective of embodied cognition, AR online shopping may be potential focus of research and market application. For the future design of online shopping platforms and the updating of user experience, this study provides a reference.

Analysis of Mental Workload in Online Shopping: Are Augmented and Virtual Reality Consistent?

PubMed Central

Zhao, Xiaojun; Shi, Changxiu; You, Xuqun; Zong, Chenming

2017-01-01

A market research company (Nielsen) reported that consumers in the Asia-Pacific region have become the most active group in online shopping. Focusing on augmented reality (AR), which is one of three major techniques used to change the method of shopping in the future, this study used a mixed design to discuss the influences of the method of online shopping, user gender, cognitive style, product value, and sensory channel on mental workload in virtual reality (VR) and AR situations. The results showed that males’ mental workloads were significantly higher than females’. For males, high-value products’ mental workload was significantly higher than that of low-value products. In the VR situation, the visual mental workload of field-independent and field-dependent consumers showed a significant difference, but the difference was reduced under audio–visual conditions. In the AR situation, the visual mental workload of field-independent and field-dependent consumers showed a significant difference, but the difference increased under audio–visual conditions. This study provided a psychological study of online shopping with AR and VR technology with applications in the future. Based on the perspective of embodied cognition, AR online shopping may be potential focus of research and market application. For the future design of online shopping platforms and the updating of user experience, this study provides a reference. PMID:28184207

Field Day at the Rec: Working Out with Physics

NASA Astrophysics Data System (ADS)

Young, Chadwick; Young, Kaisa; Buxton, Gavin; Buzzelli, Armand

2017-03-01

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 other allied health field. These students take a physics course that often has no math prerequisites, covers all of classical physics in a year, and focuses on the physics of the human body.

Frustrated honeycomb-lattice bilayer quantum antiferromagnet in a magnetic field

NASA Astrophysics Data System (ADS)

Krokhmalskii, Taras; Baliha, Vasyl; Derzhko, Oleg; Schulenburg, Jörg; Richter, Johannes

2018-05-01

Frustrated bilayer quantum magnets have attracted attention as flat-band spin systems with unconventional thermodynamic properties. We study the low-temperature properties of a frustrated honeycomb-lattice bilayer spin-1/2 isotropic (XXX) Heisenberg antiferromagnet in a magnetic field by means of an effective low-energy theory using exact diagonalizations and quantum Monte Carlo simulations. Our main focus is on the magnetization curve and the temperature dependence of the specific heat indicating a finite-temperature phase transition in high magnetic fields.

He Says, She Says: Do They "Say" in the Same Way? A Case Study of Gendered Online Communication

ERIC Educational Resources Information Center

Amakye, Augustina

2010-01-01

Gender communication, an area of focus in the mass communication interdisciplinary field, is one that has continued to grow and expand since its inception. The mid 1970's thrust this communication focus into the research limelight with Lakoff's (1975) work on gendered language use. Since then, research in this area has matured to offer not only…

Teachers as Secondary Players: Involvement in Field Trips to Natural Environments

NASA Astrophysics Data System (ADS)

Alon, Nirit Lavie; Tal, Tali

2017-08-01

This study focused on field trips to natural environments where the teacher plays a secondary role alongside a professional guide. We investigated teachers' and field trip guides' views of the teacher's role, the teacher's actual function on the field trip, and the relationship between them. We observed field trips, interviewed teachers and guides, and administered questionnaires. We found different levels of teacher involvement, ranging from mainly supervising and giving technical help, to high involvement especially in the cognitive domain and sometimes in the social domain. Analysis of students' self-reported outcomes showed that the more students believe their teachers are involved, the higher the self-reported learning outcomes.

Image translation for single-shot focal tomography

DOE PAGES

Llull, Patrick; Yuan, Xin; Carin, Lawrence; ...

2015-01-01

Focus and depth of field are conventionally addressed by adjusting longitudinal lens position. More recently, combinations of deliberate blur and computational processing have been used to extend depth of field. Here we show that dynamic control of transverse and longitudinal lens position can be used to decode focus and extend depth of field without degrading static resolution. Our results suggest that optical image stabilization systems may be used for autofocus, extended depth of field, and 3D imaging.

Electromagnetic fields of an ultra-short tightly-focused radially-polarized laser pulse

NASA Astrophysics Data System (ADS)

Salamin, Yousef I.; Li, Jian-Xing

2017-12-01

Fully analytic expressions, for the electric and magnetic fields of an ultrashort and tightly focused laser pulse of the radially polarized category, are presented to lowest order of approximation. The fields are derived from scalar and vector potentials, along the lines of our earlier work for a similar pulse of the linearly polarized variety. A systematic program is also described from which the fields may be obtained to any desired accuracy, analytically or numerically.

Magmatic Mapping: A Suggested Methodology And Results From The Springerville Volcanic Field, East-Central Arizona, USA

NASA Astrophysics Data System (ADS)

Mnich, M.; Condit, C.

2016-12-01

The Springerville Volcanic Field (SVF), located in east-central Arizona, is one of the best-characterized basaltic monogenetic volcanic fields in the world, with it's expanse of over 3000 km2 now mapped in it's entirety as a result of recent efforts in 2010 and 2011. The methods used, called "magmatic mapping" (Condit, 2007), provide a standardized, volcanic unit focused approach to characterizing volcanic fields. This approach focuses on delineating contacts between flows, completely characterizing each flow, and placing them into a temporal framework. Results of magmatic mapping in the SVF now provide a comprehensive overview of the lifespan of the field, representing a unique resource, useful not only in studying the petrogenetic evolution of this field, but in serving as a template for comparing similar volcanic fields. On Earth, several fields pose a significant risk to population centers, though these hazards are often poorly understood due to long intervals between eruptions. On other planets, remote mapping can be greatly enhanced by comparing it with a well-studied terrestrial analog that has been analyzed in detail; an area with ever heightening necessity as high-resolution data is becoming increasingly available. In the SVF, olivine phyric lavas are most abundance (22% of volcanic outcrop), followed by diktytaxitic and olivine/plagioclase phyric flows. However, lithology will vary depending on when an eruption takes place in a volcanic fields lifecycle. On the whole, the SVF is younger to the east and younger lavas are dominantly more alkalic. These trends are also displayed within individual geographic divisions, many of which correspond to temporal-geographic clusters as defined by Condit and Connor (1996). The mapping methods and patterns in geochemistry, lithology and age progression within the SVF represent a unique template for which to base basaltic mapping.

A Study by Remote Sensing Methods of Volcanism at Craters of the Moon National Park, Idaho

NASA Astrophysics Data System (ADS)

Haberle, C. W.; Hughes, S. S.; Kobs-Nawotniak, S. E.; Lim, D. S. S.; Garry, B.; Sears, D. W. G.; Downs, M.; Busto, J.; Skok, J. R.; Elphic, R. C.; Kobayashi, L.; Heldmann, J. L.; Christensen, P. R.

2014-12-01

Craters of the Moon (COTM) National Park, on the eastern Snake River Plain, and its associated lava fields are currently a focus of the NASA SSERVI FINESSE (Field Investigations to Enable Solar System Science and Exploration) team. COTM was selected for study owing to similarities with volcanic features observed on the Moon, Mars and Vesta. The COTM basaltic lava fields emanate from an 80 km long rift zone where at least eight eruptive episodes, occurring 15,000 to 2,000 BP, have created an expansive volcanic field covering an area of approximately 1,650 km2. This polygenetic volcanic field hosts a diverse collection of basaltic volcanic edifices such as phreatic explosion craters, eruptive fissures, cinder cones, spatter cones, shield volcanoes and expansive lava flows. Engineering challenges and high cost limit the number of robotic and human field investigations of planetary bodies and, due to these constraints, exhaustive remote sensing investigations of planetary surface properties are undertaken prior to field deployment. This creates an unavoidable dependence upon remote sensing, a critical difference between field investigations of planetary bodies and most terrestrial field investigations. Studies of this nature have utility in terrestrial investigations as they can help link spatially encompassing datasets and conserve field resources. We present preliminary results utilizing Earth orbital datasets to determine the efficacy of products derived from remotely sensed data when compared to geologic field observations. Multispectral imaging data (ASTER, AVIRIS, TIMS) collected at a range of spatial and spectral resolutions are paired with high resolution imagery from both orbit and unmanned aircraft systems. This enables the creation of derived products detailing morphology, compositional variation, mineralogy, relative age and vegetation. The surface morphology of flows within COTM differs from flow to flow and observations of these properties can aid in determining the driving mechanisms. The entirety of the COTM volcanic field is the target of this investigation although areas of interest have been selected for more focused investigation to support planned and ongoing field investigations at Highway A'a flow, North Crater cinder cone and King's Bowl phreatic explosion crater and flow.

Simulation study on the spatial and temporal characteristics of focused microwave beam discharge in nitrogen

NASA Astrophysics Data System (ADS)

Yang, Wei; Zhou, Qianhong; Dong, Zhiwei

2018-01-01

This paper reports a simulation study on a focused microwave (frequency 9.4 GHz, pulse width 2.5 μs, and peak electric field 1.2 kV/cm) discharge in 200 Pa nitrogen. A one-dimensional (1D) fluid model is based on the wave equation for the microwave field propagating through the gas breakdown plasma, the continuity equations for electron, ion and neutral particle densities, and the energy balance equations for mean electron temperature, and nitrogen vibrational and translational temperatures. These equations are numerically solved in a self-consistent manner with a simplified plasma chemistry set, in which the reaction rates involving electrons are calculated from the electron energy distribution function (EEDF) using a two-term expansion method. The spatial and temporal characteristics of the focused microwave breakdown in nitrogen are demonstrated, which include the amplitude of the microwave electric field, and the densities and temperatures of the plasma components. The temporal evolution of the plasma electron density agrees reasonably well with that measured with a microwave interferometer. The spatial-temporal distributions of metastable states are discussed on the plasma chemistry and the character of mean electron temperature. The spatially integrated N2(C3) density shows similar trends with the measured temporal intensity of optical emission spectroscopy, except for a time delay of 100-300 ns. The quantitative discrepancies are explained in light of limitations of the 1D model with a two-term expansion of EEDF. The theoretical model is found to describe the gas breakdown plasma generated by focused microwave beams at least qualitatively.

Home Start Evaluation Study. Interim Case Studies IIa.

ERIC Educational Resources Information Center

Fein, Robert

This formative evaluation study of Home Start uses a case study approach. A brief case study focuses on the administrative structure and staff resources and responsibilities of National Home Start. Also included are reports on seven local programs developed after two field visits had been made to each program. In the first visit, objectives chosen…

Perspectives on the Etiology of Violence in Later Life.

PubMed

Mysyuk, Yuliya; Westendorp, Rudi G J; Lindenberg, Jolanda

2016-11-01

This article focuses on the development of a conceptual framework for explaining the etiology of violence in later life by various groups involved in the field of elder abuse. In this study, we explore this through eight focus groups with different professionals involved in the field of elder abuse and older persons themselves and in interviews with 35 experts in the field. Our findings show that dependency, vulnerability, power and control, social isolation, stress, and care burden play a central role in their explanations for the occurrence of violence in later life. The role of a history of violence in violence in later life is equivocal. The complexity and ambiguity of dependency and vulnerability, the notion of mutual dependency, and diverse attitudes and expectations toward them that arise with the aging process are distinct features of violence in later life that were found. © The Author(s) 2015.

Interstellar Pickup Ion Acceleration in the Turbulent Magnetic Field at the Solar Wind Termination Shock Using a Focused Transport Approach

NASA Astrophysics Data System (ADS)

Ye, Junye; le Roux, Jakobus A.; Arthur, Aaron D.

2016-08-01

We study the physics of locally born interstellar pickup proton acceleration at the nearly perpendicular solar wind termination shock (SWTS) in the presence of a random magnetic field spiral angle using a focused transport model. Guided by Voyager 2 observations, the spiral angle is modeled with a q-Gaussian distribution. The spiral angle fluctuations, which are used to generate the perpendicular diffusion of pickup protons across the SWTS, play a key role in enabling efficient injection and rapid diffusive shock acceleration (DSA) when these particles follow field lines. Our simulations suggest that variation of both the shape (q-value) and the standard deviation (σ-value) of the q-Gaussian distribution significantly affect the injection speed, pitch-angle anisotropy, radial distribution, and the efficiency of the DSA of pickup protons at the SWTS. For example, increasing q and especially reducing σ enhances the DSA rate.

Professional Communication through Journal Articles.

ERIC Educational Resources Information Center

Rochester, Maxine K.

1996-01-01

Reviews studies of journal articles as a means of professional communication in the field of library and information science. The focus has been on content analysis and bibliometrics, which includes author, topic, and citation analysis. (LAM)

Study of magnetic perturbations on SEC vidicon tubes. [large space telescope

NASA Technical Reports Server (NTRS)

Long, D. C.; Zucchino, P.; Lowrance, J.

1973-01-01

A laboratory measurements program was conducted to determine the tolerances that must be imposed to achieve optimum performance from SEC-vidicon data sensors in the LST mission. These measurements along with other data were used to formulate recommendations regarding the necessary telemetry and remote control for the television data sensors when in orbit. The study encompassed the following tasks: (1) Conducted laboratory measurements of the perturbations which an external magnetic field produces on a magnetically focused, SEC-vidicon. Evaluated shielding approaches. (2) Experimentally evaluated the effects produced on overall performance by variations of the tube electrode potentials, and the focus, deflection and alignment fields. (3) Recommended the extent of ground control of camera parameters and camera parameter telemetry required for optimizing the performance of the television system in orbit. The experimental data are summarized in a set of graphs.

The Role of Epigenomics in Aquatic Toxicology.

PubMed

Brander, Susanne M; Biales, Adam D; Connon, Richard E

2017-10-01

Over the past decade, the field of molecular biology has rapidly incorporated epigenetic studies to evaluate organism-environment interactions that can result in chronic effects. Such responses arise from early life stage stress, the utilization of genetic information over an individual's life time, and transgenerational inheritance. Knowledge of epigenetic mechanisms provides the potential for a comprehensive evaluation of multigenerational and heritable effects from environmental stressors, such as contaminants. Focused studies have provided a greater understanding of how many responses to environmental stressors are driven by epigenetic modifiers. We discuss the promise of epigenetics and suggest future research directions within the field of aquatic toxicology, with a particular focus on the potential for identifying key heritable marks with consequential impacts at the organism and population levels. Environ Toxicol Chem 2017;36:2565-2573. © 2017 SETAC. © 2017 SETAC.

Numerical analysis of exhaust jet secondary combustion in hypersonic flow field

NASA Astrophysics Data System (ADS)

Yang, Tian-Peng; Wang, Jiang-Feng; Zhao, Fa-Ming; Fan, Xiao-Feng; Wang, Yu-Han

2018-05-01

The interaction effect between jet and control surface in supersonic and hypersonic flow is one of the key problems for advanced flight control system. The flow properties of exhaust jet secondary combustion in a hypersonic compression ramp flow field were studied numerically by solving the Navier-Stokes equations with multi-species and combustion reaction effects. The analysis was focused on the flow field structure and the force amplification factor under different jet conditions. Numerical results show that a series of different secondary combustion makes the flow field structure change regularly, and the temperature increases rapidly near the jet exit.

Effect of reheating on predictions following multiple-field inflation

NASA Astrophysics Data System (ADS)

Hotinli, Selim C.; Frazer, Jonathan; Jaffe, Andrew H.; Meyers, Joel; Price, Layne C.; Tarrant, Ewan R. M.

2018-01-01

We study the sensitivity of cosmological observables to the reheating phase following inflation driven by many scalar fields. We describe a method which allows semianalytic treatment of the impact of perturbative reheating on cosmological perturbations using the sudden decay approximation. Focusing on N -quadratic inflation, we show how the scalar spectral index and tensor-to-scalar ratio are affected by the rates at which the scalar fields decay into radiation. We find that for certain choices of decay rates, reheating following multiple-field inflation can have a significant impact on the prediction of cosmological observables.

Ultrafast electron radiography of magnetic fields in high-intensity laser-solid interactions.

PubMed

Schumaker, W; Nakanii, N; McGuffey, C; Zulick, C; Chyvkov, V; Dollar, F; Habara, H; Kalintchenko, G; Maksimchuk, A; Tanaka, K A; Thomas, A G R; Yanovsky, V; Krushelnick, K

2013-01-04

Using electron bunches generated by laser wakefield acceleration as a probe, the temporal evolution of magnetic fields generated by a 4 × 10(19) W/cm(2) ultrashort (30 fs) laser pulse focused on solid density targets is studied experimentally. Magnetic field strengths of order B(0) ~ 10(4) T are observed expanding at close to the speed of light from the interaction point of a high-contrast laser pulse with a 10-μm-thick aluminum foil to a maximum diameter of ~1 mm. The field dynamics are shown to agree with particle-in-cell simulations.

A novel calibration method of focused light field camera for 3-D reconstruction of flame temperature

NASA Astrophysics Data System (ADS)

Sun, Jun; Hossain, Md. Moinul; Xu, Chuan-Long; Zhang, Biao; Wang, Shi-Min

2017-05-01

This paper presents a novel geometric calibration method for focused light field camera to trace the rays of flame radiance and to reconstruct the three-dimensional (3-D) temperature distribution of a flame. A calibration model is developed to calculate the corner points and their projections of the focused light field camera. The characteristics of matching main lens and microlens f-numbers are used as an additional constrains for the calibration. Geometric parameters of the focused light field camera are then achieved using Levenberg-Marquardt algorithm. Total focused images in which all the points are in focus, are utilized to validate the proposed calibration method. Calibration results are presented and discussed in details. The maximum mean relative error of the calibration is found less than 0.13%, indicating that the proposed method is capable of calibrating the focused light field camera successfully. The parameters obtained by the calibration are then utilized to trace the rays of flame radiance. A least square QR-factorization algorithm with Plank's radiation law is used to reconstruct the 3-D temperature distribution of a flame. Experiments were carried out on an ethylene air fired combustion test rig to reconstruct the temperature distribution of flames. The flame temperature obtained by the proposed method is then compared with that obtained by using high-precision thermocouple. The difference between the two measurements was found no greater than 6.7%. Experimental results demonstrated that the proposed calibration method and the applied measurement technique perform well in the reconstruction of the flame temperature.

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.

FDTD approach to optical forces of tightly focused vector beams on metal particles.

PubMed

Qin, Jian-Qi; Wang, Xi-Lin; Jia, Ding; Chen, Jing; Fan, Ya-Xian; Ding, Jianping; Wang, Hui-Tian

2009-05-11

We propose an improved FDTD method to calculate the optical forces of tightly focused beams on microscopic metal particles. Comparison study on different kinds of tightly focused beams indicates that trapping efficiency can be altered by adjusting the polarization of the incident field. The results also show the size-dependence of trapping forces exerted on metal particles. Transverse tapping forces produced by different illumination wavelengths are also evaluated. The numeric simulation demonstrates the possibility of trapping moderate-sized metal particles whose radii are comparable to wavelength.

Atmospheric pressure ion focusing in a high-field asymmetric waveform ion mobility spectrometer

NASA Astrophysics Data System (ADS)

Guevremont, Roger; Purves, Randy W.

1999-02-01

The focusing of ions at atmospheric pressure and room temperature in a high-field asymmetric waveform ion mobility spectrometer (FAIMS) has been investigated. FAIMS operates with the application of a high-voltage, high-frequency asymmetric waveform across parallel plates. This establishes conditions wherein an ion migrates towards one of the plates because of a difference in the ion mobility at the low and high electric field conditions during application of the waveform. The migration can be stopped by applying a dc compensation voltage (CV) which serves to create a "balanced" condition wherein the ion experiences no net transverse motion. This method has also been called "transverse field compensation ion mobility spectrometry" and "field ion spectrometry®." If this experiment is conducted using a device with cylindrical geometry, rather than with flat plates, an ion focusing region can exist in the annular space between the two concentric cylinders. Ion trajectory modeling showed that the behavior of the ions in the cylindrical geometry FAIMS analyzer was unlike any previously described atmospheric pressure ion optics system. The ions appeared to be trapped, or focused by being caught between two opposing forces. Requirements for establishing this focus for a given ion were identified: the applied waveform must be asymmetric, the electric field must be sufficiently high that the mobility of the ion deviates from its low-field value during the high-voltage portion of the asymmetric waveform, and finally, the electric field must be nonuniform in space (e.g., cylindrical or spherical geometry). Experimental observations with a prototype FAIMS device, which was designed to measure the radial distribution of ions in the FAIMS analyzer region, have confirmed the results of ion trajectory modeling.

Sonoluminescence and sonochemiluminescence study of cavitation field in a 1.2MHz focused ultrasound

NASA Astrophysics Data System (ADS)

Yin, Hui; Qiao, Yangzi; Cao, Hua; Wan, Mingxi

2017-03-01

An intensified CCD (ICCD) and an electron-multiplying CCD (EMCCD) were employed to observe the spatial distribution of sonoluminescence (SL) and sonochemiluminescence (SCL) generated by cavitation bubbles in a 1.2MHz HIFU field. Various sonication conditions, which are free field and focal region near a water-parenchyma interface, were studied. In addition, the differences of two shells coated UCAs were also investigated. In this study, an acoustic radiation force (ARF) counterbalance appliance was added to reduce bubble displacement. Cavitation mapping in this situation was also operated through SCL recording. SCL was also employed to measure cavitation does and map the spatial distribution of cavitation near a boundary of parenchyma.

Is there a Space for Post-Colonial Theory in the Socio-Psychological Research on Consequences of Colonial Past?

PubMed

Leone, Giovanna

2018-04-26

The focus of my commentary is two-fold. First, I discuss what appeared to me as the central theoretical focus of the article; the possibility to create a space, if at all, for integrating post-colonial theory into the broader research field of social and psychological studies of the consequences of colonial past. Second, I intend to show why, in my opinion, the methodological choices of the authors and the criteria adopted for corpus construction allowed for data that, although too thin to establishing the state of knowledge in the field of study on consequences of colonial past, is nevertheless very informative and thoughts-provoking. My conclusions suggest that this study is an innovative attempt at describing and grasping the results of a search guided by two among the more consolidated electronic datasets currently available for English-speaking scholars. However, this study may not easily understand which can be the space to integrate post-colonial theory in the field of research on consequences of colonial past. To better reach this aim, it is perhaps necessary to build another kind of corpus, open to other languages (starting from French) and focused also on other scientific products, as books or proceedings of congress. In addition, disciplinary boundaries have to be even more explored, starting from interdisciplinary studies on education and historical culture. In spite of these limitations, I am convinced that this innovative study by Tomicic and Berardi tackles issues of relevance to any serious effort towards reflecting on long-term consequences of colonial violence and opens up to valuable new research questions and methods, to be taken into serious account and further explored in future works.

Fast and Adaptive Auto-focusing Microscope

NASA Astrophysics Data System (ADS)

Obara, Takeshi; Igarashi, Yasunobu; Hashimoto, Koichi

Optical microscopes are widely used in biological and medical researches. By using the microscope, we can observe cellular movements including intracellular ions and molecules tagged with fluorescent dyes at a high magnification. However, a freely motile cell easily escapes from a 3D field of view of the typical microscope. Therefore, we propose a novel auto-focusing algorithm and develop a auto-focusing and tracking microscope. XYZ positions of a microscopic stage are feedback controlled to focus and track the cell automatically. A bright-field image is used to estimate a cellular position. XY centroids are used to estimate XY positions of the tracked cell. To estimate Z position, we use a diffraction pattern around the cell membrane. This estimation method is so-called Depth from Diffraction (DFDi). However, this method is not robust for individual differences between cells because the diffraction pattern depends on each cellular shape. Therefore, in this study, we propose a real-time correction of DFDi by using 2D Laplacian of an intracellular area as a goodness of the focus. To evaluate the performance of our developed algorithm and microscope, we auto-focus and track a freely moving paramecium. In this experimental result, the paramecium is auto-focused and kept inside the scope of the microscope during 45s. The evaluated focal error is within 5µm, while a length and a thickness of the paramecium are about 200µm and 50µm, respectively.

Hello World! - Experiencing Usability Methods without Usability Expertise

NASA Astrophysics Data System (ADS)

Eriksson, Elina; Cajander, Åsa; Gulliksen, Jan

How do you do usability work when no usability expertise is available? What happens in an organization when system developers, with no previous HCI knowledge, after a 3-day course, start applying usability methods, and particularly field studies? In order to answer these questions qualitative data were gathered through participatory observations, a feed back survey, field study documentation and interviews from 47 system developers from a public authority. Our results suggest that field studies enhance the developer’s understanding of the user perspective, and provide a more holistic overview of the use situation, but that some developers were unable to interpret their observations and see solutions to the users’ problems. The field study method was very much appreciated and has now become standard operating procedure within the organization. However, although field studies may be useful, it does not replace the need for usability pro fes sion als, as their knowledge is essential for more complex observations, analysis and for keeping the focus on usability.

Electrostatic focal spot correction for x-ray tubes operating in strong magnetic fields.

PubMed

Lillaney, Prasheel; Shin, Mihye; Hinshaw, Waldo; Fahrig, Rebecca

2014-11-01

A close proximity hybrid x-ray/magnetic resonance (XMR) imaging system offers several critical advantages over current XMR system installations that have large separation distances (∼5 m) between the imaging fields of view. The two imaging systems can be placed in close proximity to each other if an x-ray tube can be designed to be immune to the magnetic fringe fields outside of the MR bore. One of the major obstacles to robust x-ray tube design is correcting for the effects of the MR fringe field on the x-ray tube focal spot. Any fringe field component orthogonal to the x-ray tube electric field leads to electron drift altering the path of the electron trajectories. The method proposed in this study to correct for the electron drift utilizes an external electric field in the direction of the drift. The electric field is created using two electrodes that are positioned adjacent to the cathode. These electrodes are biased with positive and negative potential differences relative to the cathode. The design of the focusing cup assembly is constrained primarily by the strength of the MR fringe field and high voltage standoff distances between the anode, cathode, and the bias electrodes. From these constraints, a focusing cup design suitable for the close proximity XMR system geometry is derived, and a finite element model of this focusing cup geometry is simulated to demonstrate efficacy. A Monte Carlo simulation is performed to determine any effects of the modified focusing cup design on the output x-ray energy spectrum. An orthogonal fringe field magnitude of 65 mT can be compensated for using bias voltages of +15 and -20 kV. These bias voltages are not sufficient to completely correct for larger orthogonal field magnitudes. Using active shielding coils in combination with the bias electrodes provides complete correction at an orthogonal field magnitude of 88.1 mT. Introducing small fields (<10 mT) parallel to the x-ray tube electric field in addition to the orthogonal field does not affect the electrostatic correction technique. However, rotation of the x-ray tube by 30° toward the MR bore increases the parallel magnetic field magnitude (∼72 mT). The presence of this larger parallel field along with the orthogonal field leads to incomplete correction. Monte Carlo simulations demonstrate that the mean energy of the x-ray spectrum is not noticeably affected by the electrostatic correction, but the output flux is reduced by 7.5%. The maximum orthogonal magnetic field magnitude that can be compensated for using the proposed design is 65 mT. Larger orthogonal field magnitudes cannot be completely compensated for because a pure electrostatic approach is limited by the dielectric strength of the vacuum inside the x-ray tube insert. The electrostatic approach also suffers from limitations when there are strong magnetic fields in both the orthogonal and parallel directions because the electrons prefer to stay aligned with the parallel magnetic field. These challenging field conditions can be addressed by using a hybrid correction approach that utilizes both active shielding coils and biasing electrodes.

Electrostatic focal spot correction for x-ray tubes operating in strong magnetic fields

PubMed Central

Lillaney, Prasheel; Shin, Mihye; Hinshaw, Waldo; Fahrig, Rebecca

2014-01-01

Purpose: A close proximity hybrid x-ray/magnetic resonance (XMR) imaging system offers several critical advantages over current XMR system installations that have large separation distances (∼5 m) between the imaging fields of view. The two imaging systems can be placed in close proximity to each other if an x-ray tube can be designed to be immune to the magnetic fringe fields outside of the MR bore. One of the major obstacles to robust x-ray tube design is correcting for the effects of the MR fringe field on the x-ray tube focal spot. Any fringe field component orthogonal to the x-ray tube electric field leads to electron drift altering the path of the electron trajectories. Methods: The method proposed in this study to correct for the electron drift utilizes an external electric field in the direction of the drift. The electric field is created using two electrodes that are positioned adjacent to the cathode. These electrodes are biased with positive and negative potential differences relative to the cathode. The design of the focusing cup assembly is constrained primarily by the strength of the MR fringe field and high voltage standoff distances between the anode, cathode, and the bias electrodes. From these constraints, a focusing cup design suitable for the close proximity XMR system geometry is derived, and a finite element model of this focusing cup geometry is simulated to demonstrate efficacy. A Monte Carlo simulation is performed to determine any effects of the modified focusing cup design on the output x-ray energy spectrum. Results: An orthogonal fringe field magnitude of 65 mT can be compensated for using bias voltages of +15 and −20 kV. These bias voltages are not sufficient to completely correct for larger orthogonal field magnitudes. Using active shielding coils in combination with the bias electrodes provides complete correction at an orthogonal field magnitude of 88.1 mT. Introducing small fields (<10 mT) parallel to the x-ray tube electric field in addition to the orthogonal field does not affect the electrostatic correction technique. However, rotation of the x-ray tube by 30° toward the MR bore increases the parallel magnetic field magnitude (∼72 mT). The presence of this larger parallel field along with the orthogonal field leads to incomplete correction. Monte Carlo simulations demonstrate that the mean energy of the x-ray spectrum is not noticeably affected by the electrostatic correction, but the output flux is reduced by 7.5%. Conclusions: The maximum orthogonal magnetic field magnitude that can be compensated for using the proposed design is 65 mT. Larger orthogonal field magnitudes cannot be completely compensated for because a pure electrostatic approach is limited by the dielectric strength of the vacuum inside the x-ray tube insert. The electrostatic approach also suffers from limitations when there are strong magnetic fields in both the orthogonal and parallel directions because the electrons prefer to stay aligned with the parallel magnetic field. These challenging field conditions can be addressed by using a hybrid correction approach that utilizes both active shielding coils and biasing electrodes. PMID:25370658

Polarization-Dependent Quasi-Far-Field Superfocusing Strategy of Nanoring-Based Plasmonic Lenses.

PubMed

Sun, Hao; Zhu, Yechuan; Gao, Bo; Wang, Ping; Yu, Yiting

2017-12-01

The two-dimensional superfocusing of nanoring-based plasmonic lenses (NRPLs) beyond the diffraction limit in the far-field region remains a great challenge at optical wavelengths. In this paper, in addition to the modulation of structural parameters, we investigated the polarization-dependent focusing performance of a NRPL employing the finite-difference time-domain (FDTD) method. By utilizing the state of polarization (SOP) of incident light, we successfully realize the elliptical-, donut-, and circular-shape foci. The minimum full widths at half maximum (FWHMs) of these foci are ~0.32, ~0.34, and ~0.42 λ 0 in the total electric field, respectively, and the depth of focus (DOF) lies in 1.41~1.77 λ 0 . These sub-diffraction-limit foci are well controlled in the quasi-far-field region. The underlying physical mechanism on the focal shift and an effective way to control the focusing position are proposed. Furthermore, in the case of a high numerical aperture, the longitudinal component, which occupies over 80% of the electric-field energy, decides the focusing patterns of the foci. The achieved sub-diffraction-limit focusing can be widely used for many engineering applications, including the super-resolution imaging, particle acceleration, quantum optical information processing, and optical data storage.

Design and development of a magnetic device for mesenchymal stem cell retaining in deep targets

NASA Astrophysics Data System (ADS)

Banis, G. C.

2017-12-01

This paper focuses on the retaining of mesenchymal stem cells in blood flow conditions using the appropriate magnetic field. Mesenchymal stem cells can be tagged with magnetic nanoparticles and thus, they can be manipulated from distance, through the application of an external magnetic field. In this paper the case of kidney as target of the therapy is being studied.

Un champ semantique: les noms d'appartenance raciale au Honduras britannique (A Semantic Field: Names of Racial Identity in the British Honduras)

ERIC Educational Resources Information Center

Tabouret-Keller, Andree

1975-01-01

This article studies the problem of social identity among six different racial groups in the British Honduras, focusing on what the groups call themselves and what others call them, and on the semantic field of these terms, i.e. the socio-cultural values they represent. (Text is in French.) (AM)

The Organization of Schools as an Overlooked Source of Underqualified Teaching. Teaching Quality Policy Briefs. Number 7

ERIC Educational Resources Information Center

Center for the Study of Teaching and Policy, 2002

2002-01-01

The study reported in this policy brief focuses on one aspect of unequal distribution of quality teaching--out-of-field placement. In schools serving primarily low-income and/or minority students, out-of-field teaching is an acute problem and occurs even though the causes have little to do with the lack of certified teachers. Rather, school…

A numerical investigation of the interplay between fireline length, geometry, and rate of spread

Treesearch

J. M. Canfield; R. R. Linn; J. A. Sauer; M. Finney; J. Forthofer

2014-01-01

The current study focuses on coupled dynamics and resultant geometry of fireline segments of various ignition lengths. As an example, for ignition lines of length scales typical for field experiments, fireline curvature is the result of a competition between the head fire and the flanks of the fire. A number of physical features (i.e. buoyancy and wind field divergence...

A Field-Based Biomimicry Exercise Helps Students Discover Connections among Biodiversity, Form and Function, and Species Conservation during Earth's Sixth Extinction

ERIC Educational Resources Information Center

Soja, Constance M.

2014-01-01

In a first-year seminar on mass extinctions, a field-based, paleontology-focused exercise promotes active learning about Earth's biodiversity, form and function, and the biomimicry potential of ancient and modern life. Students study Devonian fossils at a local quarry and gain foundational experience in describing anatomy and relating form to…

Tourism Studies. Guide to Standards and Implementation. Career & Technology Studies.

ERIC Educational Resources Information Center

Alberta Dept. of Education, Edmonton. Curriculum Standards Branch.

This Alberta curriculum guide, focusing on tourism studies, defines competencies that: help students build daily living skills, investigate career options in the design and repair of motor vehicles, use technology in these fields effectively and efficiently, and prepare for entry into the workplace or related postsecondary programs. Section A…

Comparative Studies in Special Education.

ERIC Educational Resources Information Center

Mazurek, Kas, Ed.; Winzer, Margret A., Ed.

This text presents 26 case studies which examine special education provisions for children in the world today. The reports focus on the current state of special education in selected nations and major issues and controversies in the field of special education within those nations. Each case study addresses the following themes: (1) prevalence of…

Extended depth of field integral imaging using multi-focus fusion

NASA Astrophysics Data System (ADS)

Piao, Yongri; Zhang, Miao; Wang, Xiaohui; Li, Peihua

2018-03-01

In this paper, we propose a new method for depth of field extension in integral imaging by realizing the image fusion method on the multi-focus elemental images. In the proposed method, a camera is translated on a 2D grid to take multi-focus elemental images by sweeping the focus plane across the scene. Simply applying an image fusion method on the elemental images holding rich parallax information does not work effectively because registration accuracy of images is the prerequisite for image fusion. To solve this problem an elemental image generalization method is proposed. The aim of this generalization process is to geometrically align the objects in all elemental images so that the correct regions of multi-focus elemental images can be exacted. The all-in focus elemental images are then generated by fusing the generalized elemental images using the block based fusion method. The experimental results demonstrate that the depth of field of synthetic aperture integral imaging system has been extended by realizing the generation method combined with the image fusion on multi-focus elemental images in synthetic aperture integral imaging system.

Perpendicular Diffusion Coefficient of Comic Rays: The Presence of Weak Adiabatic Focusing

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

Wang, J. F.; Ma, Q. M.; Song, T.

The influence of adiabatic focusing on particle diffusion is an important topic in astrophysics and plasma physics. In the past, several authors have explored the influence of along-field adiabatic focusing on the parallel diffusion of charged energetic particles. In this paper, using the unified nonlinear transport theory developed by Shalchi and the method of He and Schlickeiser, we derive a new nonlinear perpendicular diffusion coefficient for a non-uniform background magnetic field. This formula demonstrates that the particle perpendicular diffusion coefficient is modified by along-field adiabatic focusing. For isotropic pitch-angle scattering and the weak adiabatic focusing limit, the derived perpendicular diffusionmore » coefficient is independent of the sign of adiabatic focusing characteristic length. For the two-component model, we simplify the perpendicular diffusion coefficient up to the second order of the power series of the adiabatic focusing characteristic quantity. We find that the first-order modifying factor is equal to zero and that the sign of the second order is determined by the energy of the particles.« less

Recommendations for Guidelines for Environment-Specific Magnetic-Field Measurements, Rapid Program Engineering Project #2

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

Electric Research and Management, Inc.; IIT Research Institute; Magnetic Measurements

1997-03-11

The purpose of this project was to document widely applicable methods for characterizing the magnetic fields in a given environment, recognizing the many sources co-existing within that space. The guidelines are designed to allow the reader to follow an efficient process to (1) plan the goals and requirements of a magnetic-field study, (2) develop a study structure and protocol, and (3) document and carry out the plan. These guidelines take the reader first through the process of developing a basic study strategy, then through planning and performing the data collection. Last, the critical factors of data management, analysis reporting, andmore » quality assurance are discussed. The guidelines are structured to allow the researcher to develop a protocol that responds to specific site and project needs. The Research and Public Information Dissemination Program (RAPID) is based on exposure to magnetic fields and the potential health effects. Therefore, the most important focus for these magnetic-field measurement guidelines is relevance to exposure. The assumed objective of an environment-specific measurement is to characterize the environment (given a set of occupants and magnetic-field sources) so that information about the exposure of the occupants may be inferred. Ideally, the researcher seeks to obtain complete or "perfect" information about these magnetic fields, so that personal exposure might also be modeled perfectly. However, complete data collection is not feasible. In fact, it has been made more difficult as the research field has moved to expand the list of field parameters measured, increasing the cost and complexity of performing a measurement and analyzing the data. The guidelines address this issue by guiding the user to design a measurement protocol that will gather the most exposure-relevant information based on the locations of people in relation to the sources. We suggest that the "microenvironment" become the base unit of area in a study, with boundaries defined by the occupant's activity patterns and the field variation from the sources affecting the area. Such a stratification allows the researcher to determine which microenvironment are of most interest, and to methodically focus the areas, in order to gather the most relevant set of data.« less

Electron kinematics in a plasma focus

NASA Technical Reports Server (NTRS)

Hohl, F.; Gary, S. P.

1977-01-01

The results of numerical integrations of the three-dimensional relativistic equations of motion of electrons subject to given electric and magnetic fields are presented. Fields due to two different models are studied: (1) a circular distribution of current filaments, and (2) a uniform current distribution; both the collapse and the current reduction phases are studied in each model. Decreasing current in the uniform current model yields 100 keV electrons accelerated toward the anode and, as for earlier ion computations, provides general agreement with experimental results.

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.

Fluid-rock geochemical interaction for modelling calibration in geothermal exploration in Indonesia

NASA Astrophysics Data System (ADS)

Deon, Fiorenza; Barnhoorn, Auke; Lievens, Caroline; Ryannugroho, Riskiray; Imaro, Tulus; Bruhn, David; van der Meer, Freek; Hutami, Rizki; Sibarani, Besteba; Sule, Rachmat; Saptadij, Nenny; Hecker, Christoph; Appelt, Oona; Wilke, Franziska

2017-04-01

Indonesia with its large, but partially unexplored geothermal potential is one of the most interesting and suitable places in the world to conduct geothermal exploration research. This study focuses on geothermal exploration based on fluid-rock geochemistry/geomechanics and aims to compile an overview on geochemical data-rock properties from important geothermal fields in Indonesia. The research carried out in the field and in the laboratory is performed in the framework of the GEOCAP cooperation (Geothermal Capacity Building program Indonesia- the Netherlands). The application of petrology and geochemistry accounts to a better understanding of areas where operating power plants exist but also helps in the initial exploration stage of green areas. Because of their relevance and geological setting geothermal fields in Java, Sulawesi and the sedimentary basin of central Sumatra have been chosen as focus areas of this study. Operators, universities and governmental agencies will benefit from this approach as it will be applied also to new green-field terrains. By comparing the characteristic of the fluids, the alteration petrology and the rock geochemistry we also aim to contribute to compile an overview of the geochemistry of the important geothermal fields in Indonesia. At the same time the rock petrology and fluid geochemistry will be used as input data to model the reservoir fluid composition along with T-P parameters with the geochemical workbench PHREEQC. The field and laboratory data are mandatory for both the implementation and validation of the model results.

Gendered Expectations: Examining How Peers Shape Female Students' Intent to Pursue STEM Fields.

PubMed

Riegle-Crumb, Catherine; Morton, Karisma

2017-01-01

Building on prior psychological and sociological research on the power of local environments to shape gendered outcomes in STEM fields, this study focuses on the critical stage of adolescence to explore the potential negative impact of exposure to exclusionary messages from peers within girls' science classrooms, as well as the positive potential impact of inclusionary messages. Specifically, utilizing longitudinal data from a diverse sample of adolescent youth, analyses examine how the presence of biased male peers, as well as confident female peers, shape girls' subsequent intentions to pursue different STEM fields, focusing specifically on intentions to pursue the male-dominated fields of computer science and engineering, as well as more gender equitable fields. Results reveal that exposure to a higher percentage of 8th grade male peers in the classroom who endorsed explicit gender/STEM stereotypes significantly and negatively predicted girls' later intentions to pursue a computer science/engineering (CS/E) major. Yet results also reveal that exposure to a higher percentage of confident female peers in the science classroom positively predicted such intentions. These results were specific to CS/E majors, suggesting that peers are an important source of messages regarding whether or not girls should pursue non-traditional STEM fields. This study calls attention to the importance of examining both positive and negative sources of influence within the local contexts where young people live and learn. Limitations and directions for future research are also discussed.

Gendered Expectations: Examining How Peers Shape Female Students' Intent to Pursue STEM Fields

PubMed Central

Riegle-Crumb, Catherine; Morton, Karisma

2017-01-01

Building on prior psychological and sociological research on the power of local environments to shape gendered outcomes in STEM fields, this study focuses on the critical stage of adolescence to explore the potential negative impact of exposure to exclusionary messages from peers within girls' science classrooms, as well as the positive potential impact of inclusionary messages. Specifically, utilizing longitudinal data from a diverse sample of adolescent youth, analyses examine how the presence of biased male peers, as well as confident female peers, shape girls' subsequent intentions to pursue different STEM fields, focusing specifically on intentions to pursue the male-dominated fields of computer science and engineering, as well as more gender equitable fields. Results reveal that exposure to a higher percentage of 8th grade male peers in the classroom who endorsed explicit gender/STEM stereotypes significantly and negatively predicted girls' later intentions to pursue a computer science/engineering (CS/E) major. Yet results also reveal that exposure to a higher percentage of confident female peers in the science classroom positively predicted such intentions. These results were specific to CS/E majors, suggesting that peers are an important source of messages regarding whether or not girls should pursue non-traditional STEM fields. This study calls attention to the importance of examining both positive and negative sources of influence within the local contexts where young people live and learn. Limitations and directions for future research are also discussed. PMID:28360868

Virtual solar field - An opportunity to optimize transient processes in line-focus CSP power plants

NASA Astrophysics Data System (ADS)

Noureldin, Kareem; Hirsch, Tobias; Pitz-Paal, Robert

2017-06-01

Optimizing solar field operation and control is a key factor to improve the competitiveness of line-focus solar thermal power plants. However, the risks of assessing new and innovative control strategies on operational power plants hinder such optimizations and result in applying more conservative control schemes. In this paper, we describe some applications for a whole solar field transient in-house simulation tool developed at the German Aerospace Centre (DLR), the Virtual Solar Field (VSF). The tool offers a virtual platform to simulate real solar fields while coupling the thermal and hydraulic conditions of the field with high computational efficiency. Using the tool, developers and operator can probe their control strategies and assess the potential benefits while avoiding the high risks and costs. In this paper, we study the benefits gained from controlling the loop valves and of using direct normal irradiance maps and forecasts for the field control. Loop valve control is interesting for many solar field operators since it provides a high degree of flexibility to the control of the solar field through regulating the flow rate in each loop. This improves the reaction to transient condition, such as passing clouds and field start-up in the morning. Nevertheless, due to the large number of loops and the sensitivity of the field control to the valve settings, this process needs to be automated and the effect of changing the setting of each valve on the whole field control needs to be taken into account. We used VSF to implement simple control algorithms to control the loop valves and to study the benefits that could be gained from using active loop valve control during transient conditions. Secondly, we study how using short-term highly spatially-resolved DNI forecasts provided by cloud cameras could improve the plant energy yield. Both cases show an improvement in the plant efficiency and outlet temperature stability. This paves the road for further investigations of new control strategies or for optimizations of the currently implemented ones.

Modeling the Radiation Belts During a Geomagnetic Storm

NASA Astrophysics Data System (ADS)

Glocer, A.; Fok, M.; Toth, G.

2009-05-01

We utilize the Radiation Belt Environment (RBE) model to simulate the radiation belt electrons during a geomagnetic storm. Particularly, we focus on the relative contribution of whistler mode wave-particle interactions and radial diffusion associated with rapid changes in the magnetospheric magnetic field. In our study, the RBE model obtains a realistic magnetic field from the BATS-R-US magnetosphere model at a regular, but adjustable, cadence. We simulate the storm with and without wave particle interactions, and with different frequencies for updating the magnetic field. The impacts of the wave-particle interactions, and the rapid variations in the magnetospheric magnetic field, can then be studied. Simulation results are also extracted along various satellite trajectories for direct comparison where appropriate.

Evaluating the implementation of health and safety innovations under a regulatory context: a collective case study of Ontario's safer needle regulation.

PubMed

Chambers, Andrea; Mustard, Cameron A; Breslin, Curtis; Holness, Linn; Nichol, Kathryn

2013-01-22

Implementation effectiveness models have identified important factors that can promote the successful implementation of an innovation; however, these models have been examined within contexts where innovations are adopted voluntarily and often ignore the socio-political and environmental context. In the field of occupational health and safety, there are circumstances where organizations must adopt innovations to comply with a regulatory standard. Examining how the external environment can facilitate or challenge an organization's change process may add to our understanding of implementation effectiveness. The objective of this study is to describe implementation facilitators and barriers in the context of a regulation designed to promote the uptake of safer engineered medical devices in healthcare. The proposed study will focus on Ontario's safer needle regulation (2007) which requires healthcare organizations to transition to the use of safer engineered medical devices for the prevention of needlestick injuries. A collective case study design will be used to learn from the experiences of three acute care hospitals in the province of Ontario, Canada. Interviews with management and front-line healthcare workers and analysis of supporting documents will be used to describe the implementation experience and examine issues associated with the integration of these devices. The data collection and analysis process will be influenced by a conceptual framework that draws from implementation science and the occupational health and safety literature. The focus of this study in addition to the methodology creates a unique opportunity to contribute to the field of implementation science. First, the study will explore implementation experiences under circumstances where regulatory pressures are influencing the organization's change process. Second, the timing of this study provides an opportunity to focus on issues that arise during later stages of implementation, a phase during the implementation cycle that has been understudied. This study also provides the opportunity to examine the relevance and utility of current implementation science models in the field of occupational health where the adoption of an innovation is meant to enhance the health and safety of workers. Previous work has tended to focus almost exclusively on innovations that are designed to enhance an organization's productivity or competitive advantage.

The "Scholar's Anthology": Televisual Studies.

ERIC Educational Resources Information Center

Gronbeck, Bruce E., Ed.

1983-01-01

The five major articles in this journal issue focus on television criticism as an academic field. An introduction, entitled "The 'Scholar's Anthology': Televisual Studies" (Bruce Gronbeck), is followed by articles discussing the following topics: (1) the discourses of television quiz programs (John Fiske), (2) the dialectic of feminine…

Linking the Central Office and Its Schools for Reform

ERIC Educational Resources Information Center

Johnson, Peggy E.; Chrispeels, Janet H.

2010-01-01

Purpose: This study investigates how linkages between a central office and its schools served as administrative controls while fostering professional accountability and organizational learning. Method: Using qualitative data sources (interviews, focus groups, observations, field notes, and document reviews), the study examines how resource,…

Perceptions of Self-Efficacy among STEM Students with Disabilities

ERIC Educational Resources Information Center

Jenson, Ronda J.; Petri, Alexis N.; Day, Arden D.; Truman, Kevin Z.; Duffy, Kate

2011-01-01

Numerous studies examine the relationship between self-efficacy and positive outcomes for postsecondary students. Collectively they echo that self-efficacy is an essential component to positive outcomes. Relatively few studies focused on students with disabilities majoring in STEM fields. Twenty postsecondary students with disabilities…

Innovativeness and the Organizational Attributes of Schools.

ERIC Educational Resources Information Center

Eidell, Terry L.; And Others

Five papers focus on the interrelated themes of school organization and innovation. They report on some preliminary analyses of field studies conducted during 1968 on such structural, sociocultural, and sociopsychological variables as division of labor, performance of organizational functions, decision making studies and processes, hierarchies of…

Focused opening of the sylvian fissure for microsurgical management of MCA aneurysms.

PubMed

Elsharkawy, Ahmed; Niemelä, Mika; Lehečka, Martin; Lehto, Hanna; Jahromi, Behnam Rezai; Goehre, Felix; Kivisaari, Riku; Hernesniemi, Juha

2014-01-01

A wide sylvian opening, with either a proximal or distal start, has been standard for microsurgical management of middle cerebral artery (MCA) aneurysms. However, extensive sylvian dissection is potentially associated with increased incidence of iatrogenic injury to the brain and neurovascular structures. The aim of the present study was to describe the technique of focused opening of the sylvian fissure for microsurgical management of MCA aneurysms with additional tips on handling difficulties which may be encountered with this technique. A 3D image-based anatomic orientation, clipping field-focused surgical planning, slack brain, and high magnification are the basic requirements for this approach. A 10-15 mm sylvian opening is placed so that it allows safe access and a good surgical view of the MCA aneurysm clipping field. Under proximal control of the MCA, the aneurysm neck can be dissected and clipped effectively and safely, in this small surgical field. The presented technique has been developed and refined by the senior author during the surgery of 1,097 aneurysms over the last 13 years. It has proved to be safe, and effective for clipping of both ruptured and unruptured MCA aneurysms. Its greatest advantages are a shorter operative time and less brain and vessel manipulation compared to more extensive approaches. The focused sylvian opening is a less-invasive alternative to the classical wide sylvian opening for the microsurgical management of most MCA aneurysms.

PDF approach for turbulent scalar field: Some recent developments

NASA Technical Reports Server (NTRS)

Gao, Feng

1993-01-01

The probability density function (PDF) method has been proven a very useful approach in turbulence research. It has been particularly effective in simulating turbulent reacting flows and in studying some detailed statistical properties generated by a turbulent field There are, however, some important questions that have yet to be answered in PDF studies. Our efforts in the past year have been focused on two areas. First, a simple mixing model suitable for Monte Carlo simulations has been developed based on the mapping closure. Secondly, the mechanism of turbulent transport has been analyzed in order to understand the recently observed abnormal PDF's of turbulent temperature fields generated by linear heat sources.

Study of polarization properties of fiber-optics probes with use of a binary phase plate.

PubMed

Alferov, S V; Khonina, S N; Karpeev, S V

2014-04-01

We conduct a theoretical and experimental study of the distribution of the electric field components in the sharp focal domain when rotating a zone plate with a π-phase jump placed in the focused beam. Comparing the theoretical and experimental results for several kinds of near-field probes, an analysis of the polarization sensitivity of different types of metal-coated aperture probes is conducted. It is demonstrated that with increasing diameter of the non-metal-coated tip part there occurs an essential redistribution of sensitivity in favor of the transverse electric field components and an increase of the probe's energy throughput.

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.

Pre-Mission Input Requirements to Enable Successful Sample Collection by A Remote Field/EVA Team

NASA Technical Reports Server (NTRS)

Cohen, B. A.; Lim, D. S. S.; Young, K. E.; Brunner, A.; Elphic, R. E.; Horne, A.; Kerrigan, M. C.; Osinski, G. R.; Skok, J. R.; Squyres, S. W.;

Evaluation of Zeolite Permeable Treatment Wall for the Removal of Strontium-90 from Groundwater

NASA Astrophysics Data System (ADS)

Seneca, S. M.; Bandilla, K.; Rabideau, A. J.; Ross, E.; Bronner, C. E.

2009-12-01

Experimental and modeling studies are in progress to evaluate the potential performance of a permeable treatment wall comprised of zeolite-rich rock for the removal of strontium-90 from groundwater. Column studies were performed using a synthetic groundwater referenced to anticipate field conditions, with a focus on quantifying the competitive ion exchange among five cations (Na+, K+, Ca2+, Mg2+, and Sr2+). Ongoing studies are focused on the comparison of zeolites obtained from two sources: Teague Mineral Products (Adrian, OR) and Bear River Zeolite (Preston, UT), and on the possible influence of native soil that is mixed with treatment wall material during construction. The data obtained from the column studies is used to support robust estimation of zeolite cation exchange parameters producing a five-solute cation exchange model describing the removal efficiency of the zeolite. The field-scale transport model provides flexibility to explore design parameters to support the possible deployment of a full scale treatment wall at a Western New York nuclear facility.

A 1 GeV CW FFAG High Intensity Proton Driver

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

Johnstone, C.; Sheehy, S. L.

2012-05-01

The drive for high beam power, high duty cycle, and reliable beams at reasonable cost has focused world attention on fixed-field accelerators, notably Fixed-Field Alternating Gradient accelerators (FFAGs). High-intensity GeV proton drivers are of particular interest, as these encounter duty cycle and space-charge limits in the synchrotron and machine size concerns in the weaker-focusing cyclotron. Recently, the concept of isochronous orbits has been explored and developed for non-scaling FFAGs using powerful new methodologies in FFAG accelerator design. These new breeds of FFAGs have been identified by international collaborations for serious study thanks to their potential applications including Accelerator Driven Subcriticalmore » Reactors (ADS) a nd Accelerator Transmutation of Waste. The extreme reliability requirements for ADS mandate CW operation capability and the FFAG s strong focusing, particularly in the vertical, will serve to mitigate the effect of space charge (as compared with the weak- focusing cyclotron). This paper reports on these new advances in FFAG accelerator technology and presents a stable, 0.25-1GeV isochronous FFAG for an accelerator driven subcritical reactor.« less

Role of parafovea in blur perception.

PubMed

Venkataraman, Abinaya Priya; Radhakrishnan, Aiswaryah; Dorronsoro, Carlos; Lundström, Linda; Marcos, Susana

2017-09-01

The blur experienced by our visual system is not uniform across the visual field. Additionally, lens designs with variable power profile such as contact lenses used in presbyopia correction and to control myopia progression create variable blur from the fovea to the periphery. The perceptual changes associated with varying blur profile across the visual field are unclear. We therefore measured the perceived neutral focus with images of different angular subtense (from 4° to 20°) and found that the amount of blur, for which focus is perceived as neutral, increases when the stimulus was extended to cover the parafovea. We also studied the changes in central perceived neutral focus after adaptation to images with similar magnitude of optical blur across the image or varying blur from center to the periphery. Altering the blur in the periphery had little or no effect on the shift of perceived neutral focus following adaptation to normal/blurred central images. These perceptual outcomes should be considered while designing bifocal optical solutions for myopia or presbyopia. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Applications and Implications of Heparin and Protamine in Tissue Engineering and Regenerative Medicine

PubMed Central

Nemeno, Judee Grace E.; Lee, Kyung Mi

2014-01-01

Drug repositioning is one of the most rapidly emerging fields of study. This concept is anchored on the principle that diseases have similar damaged or affected signaling pathways. Recently, drugs have been repositioned not only for their alternative therapeutic uses but also for their applications as biomaterials in various fields. However, medical drugs as biomaterials are rarely focused on in reviews. Fragmin and protamine have been recently the sources of increasing attention in the field of tissue engineering and regenerative medicine. Fragmin and protamine have been manufactured primarily as a safe antidote for the circulating heparin. Lately, these drugs have been utilized as either micro- or nanoparticle biomaterials. In this paper, we will briefly describe the concept of drug repositioning and some of the medical drugs that have been repurposed for their alternative therapeutic uses. Also, this will feature the historical background of the studies focused on fragmin/protamine micro/nanoparticles (F/P M/NPs) and their applications as biomaterials in tissue engineering, stem cell therapy, and regenerative medicine. PMID:24995338

Hydrogeochemical investigations in the Osgood mountains, north-central Nevada. Chapter B.

USGS Publications Warehouse

Wanty, Richard B.; Berger, Byron R.; Tuttle, Michele L.W.; Briggs, Paul H.; Meier, Allen L.; Crock, James G.; Stillings, Lisa L.

2006-01-01

Field investigations performed in the Osgood Mountains during the summers of 1999 and 2000 were designed to test methods of combining geologic, hydrologic, and geochemical investigations. The goals were to develop a more thorough understanding of the movement of water through the study area and to understand the water-rock reactions that may occur along flow paths. The Osgood Mountains were chosen for study because they represent a well-defined geologic system, based on existing and new field data. New work in the area focused on gathering more data about fractures, faults, and joints and on collecting water samples to evaluate the role of geologic structures on hydrologic and geochemical properties of the ground-water/surface-water system. Chemical methods employed in the study included measuring traditional field parameters (e.g., pH, temperature, conductivity, dissolved oxygen) as well as Fe2+ and collecting a variety of samples that were preserved for later laboratory analysis. Hydrologic methods included closely spaced evaluations of substream hydraulic head to define ground-water discharge and recharge zones as well as some measurements of stream discharge. Geologic investigations focused on the locations and orientations of fractures and kinematic indicators of slip observable in outcrops.

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

NASA Astrophysics Data System (ADS)

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

2016-01-01

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

The Challenge of Integration in Interdisciplinary Education

ERIC Educational Resources Information Center

Minnis, Michele; John-Steiner, Vera

2005-01-01

Focused on an interdisciplinary graduate program in water resources management, this case study illustrates how theory-into-practice integration occurred in a field course and clarified students' expectations that faculty model interdisciplinary ways of knowing.

[Ethnography and nursing research].

PubMed

Chuang, Yeu-Hui; Abbey, Jennifer

2005-12-01

Ethnography, a qualitative research method developed within the field of anthropology, has been increasingly applied to a variety of fields, including sociology, education, and nursing. Ethnography works to understand the behavior and views of a particular cultural group from that group's own perspective. Traditionally, ethnography has been differentiated into classic ethnography, systematic ethnography, interpretive ethnography, and critical ethnography. A recently developed focused ethnography studies specific issues within a single culture or social situation among a limited number of people within a specific period of time. Focused ethnography is particularly relevant to the field of health sciences and holds significant potential to contribute to nursing knowledge and to help improve nursing practice. A search of Medline, CINAHL, Eric, PsycINFO, and the Index to Chinese Periodical Literature database found that ethnography has seldom been applied or discussed in the nursing literature in Taiwan. Therefore, the aim of this article is focused on introducing ethnography and understanding the applications of ethnography in nursing research. Relevant nursing literature published between 2000 and 2005 is summarized and the authors hope that this paper will give Taiwanese nursing professionals a better appreciation of this methodology and encourage its wider application in nursing research.

Tissue interactions with nonionizing electromagnetic fields. Final report, March 1979-February 1986

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

Adey, W.R.; Bawin, S.M.; Byus, C.V.

1986-08-01

This report provides an overview of this research program focused on basic research in nervous system responses to electric fields at 60 Hz. The emphasis in this project was to determine the fundamental mechanisms underlying some phenomena of electric field interactions in neural systems. The five studies of the initial program were tests of behavioral responses in the rat based upon the hypothesis that electric field detection might follow psychophysical rules known from prior research with light, sound and other stimuli; tests of electrophysiological responses to ''normal'' forms of stimulation in rat brain tissue exposed in vitro to electric fields,more » based on the hypothesis that the excitability of brain tissue might be affected by fields in the extracellular environment; tests of electrophysiological responses of spontaneously active pacemaker neurons of the Aplysia abdominal ganglion, based on the hypothesis that electric field interactions at the cell membrane might affect the balance among the several membrane-related processes that govern pacemaker activity; studies of mechanisms of low frequency electromagnetic field interactions with bone cells in the context of field therapy of ununited fractures; and manipulation of cell surface receptor proteins in studies of their mobility during EM field exposure.« less

Simultaneous negative refraction and focusing of fundamental frequency and second-harmonic fields by two-dimensional photonic crystals

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

Zhang, Jun; College of Physics and Electronic Engineering, Henan Normal University, 453007 Xinxiang, Henan; Zhang, Xiangdong, E-mail: zhangxd@bit.edu.cn

2015-09-28

Simultaneous negative refraction for both the fundamental frequency (FF) and second-harmonic (SH) fields in two-dimensional nonlinear photonic crystals have been found through both the physical analysis and exact numerical simulation. By combining such a property with the phase-matching condition and strong second-order susceptibility, we have designed a SH lens to realize focusing for both the FF and SH fields at the same time. Good-quality non-near field images for both FF and SH fields have been observed. The physical mechanism for such SH focusing phenomena has been disclosed, which is different from the backward SH generation as has been pointed outmore » in the previous investigations. In addition, the effect of absorption losses on the phenomena has also been discussed. Thus, potential applications of these phenomena to biphotonic microscopy technique are anticipated.« less

Manipulation of radial-variant polarization for creating tunable bifocusing spots.

PubMed

Gu, Bing; Pan, Yang; Wu, Jia-Lu; Cui, Yiping

2014-02-01

We propose and generate a new radial-variant vector field (RV-VF) with a distribution of states of polarization described by the square of the radius and exploit its focusing property. Theoretically, we present the analytical expressions for the three-dimensional electric field of the vector field focused by a thin lens under the nonparaxial and paraxial approximations based on the vectorial Rayleigh-Sommerfeld formulas. Numerical simulations indicate that this focused field exhibits bifocusing spots along the optical axis. The underlying mechanism for generating the bifocusing property is analyzed in detail. We give the analytical formula for the interval between two foci. Experimentally, we generate the RV-VFs with alterable topological charge and demonstrate that the interval between two foci is controllable by tuning the radial topological charge. This particular focal field has specific applications for biparticle trapping, manipulating, alignment, transportation, and accelerating along the optical axis.

Particle dynamics and pair production in tightly focused standing wave

NASA Astrophysics Data System (ADS)

Jirka, M.; Klimo, O.; Vranić, M.; Weber, S.; Korn, G.

2017-05-01

With the advent of 10 PW laser facilities, new regimes of laser-matter interaction are opening since effects of quantum electrodynamics, such as electron-positron pair production and cascade development, start to be important. The dynamics of light charged particles, such as electrons and positrons, is affected by the radiation reaction force. This effect can strongly influence the interaction of intense laser pulses with matter since it lowers the energy of emitting particles and transforms their energy to the gamma radiation. Consequently, electron-positron pairs can be generated via Breit-Wheeler process. To study this new regime of interaction, numerical simulations are required. With their help it is possible to predict and study quantum effects which may occur in future experiments at modern laser facilities. In this work we present results of electron interaction with an intense standing wave formed by two colliding laser pulses. Due to the necessity to achieve ultra intense laser field, the laser beam has to be focused to a μm-diameter spot. Since the paraxial approximation is not valid for tight focusing, the appropriate model describing the tightly focused laser beam has to be employed. In tightly focused laser beam the longitudinal component of the electromagnetic field becomes significant and together with the ponderomotive force they affect the dynamics of interacting electrons and also newly generated Breit-Wheeler electron-positron pairs. Using the Particle-In-Cell code we study electron dynamics, gamma radiation and pair production in such a configuration for linear polarization and different types of targets.

Electric field measurements from Halley, Antarctica

NASA Astrophysics Data System (ADS)

Nicoll, Keri; Harrison, R. Giles

2016-04-01

Antarctica is a unique location for the study of atmospheric electricity. Not only is it one of the most pollutant free places on Earth, but its proximity to the south magnetic pole means that it is an ideal location to study the effects of solar variability on the atmospheric electric field. This is due to the reduced shielding effect of the geomagnetic field at the poles which leads to a greater flux of incoming Galactic Cosmic Rays (GCRs) as well as an increased probability of energetic particle precipitation from SEPs and relativistic electrons. To investigate such effects, two electric field mills of different design were installed at the British Antarctic Survey Halley base in February 2015 (75. 58 degrees south, 26.66 degrees west). Halley is situated on the Brunt Ice Shelf in the south east of the Weddell Sea and has snow cover all year round. Preliminary analysis has focused on selection of fair weather criteria using wind speed and visibility measurements which are vital to assess the effects of falling snow, blowing snow and freezing fog on the electric field measurements. When the effects of such adverse weather conditions are removed clear evidence of the characteristic Carnegie Curve diurnal cycle exists in the Halley electric field measurements (with a mean value of 50V/m and showing a 40% peak to peak variation in comparison to the 34% variation in the Carnegie data). Since the Carnegie Curve represents the variation in thunderstorm activity across the Earth, its presence in the Halley data confirms the presence of the global atmospheric electric circuit signal at Halley. The work presented here will discuss the details of the Halley electric field dataset, including the variability in the fair weather measurements, with a particular focus on magnetic field fluctuations.

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).

Transverse spin in the scattering of focused radially and azimuthally polarized vector beams

NASA Astrophysics Data System (ADS)

Singh, Ankit Kumar; Saha, Sudipta; Gupta, Subhasish Dutta; Ghosh, Nirmalya

2018-04-01

We study the effect of focusing of the radially and azimuthally polarized vector beams on the spin angular momentum (SAM) density and Poynting vector of scattered waves from a Mie particle. Remarkably, the study reveals that the SAM density of the scattered field is solely transverse in nature for radially and azimuthally polarized incident vector beams; however, the Poynting vector shows the usual longitudinal character. We also demonstrate that the transverse SAM density can further be tuned with wavelength and focusing of the incident beam by exploiting the interference of different scattering modes. These results may stimulate further experimental techniques to detect the transverse spin and Belinfante's spin-momentum densities.

The Impact of Natural Disasters on Youth: A Focus on Emerging Research beyond Internalizing Disorders.

PubMed

Self-Brown, Shannon; Lai, Betty; Patterson, Alexandria; Glasheen, Theresa

2017-08-01

This paper reviews youth outcomes following exposure to natural disaster, with a focus on three relatively understudied outcomes: externalizing behavior problems, physical health, and posttraumatic growth. Recent, high-impact studies focusing on each outcome are summarized. Studies highlighted in this review utilize innovative and comprehensive approaches to improve our current understanding of youth broad-based physical and mental health outcomes beyond PTSD. The review concludes with recommendations to advance the field of youth disaster research by exploring how disasters may impact children across multiple domains, as well as using cutting edge ecobiological approaches and advanced modeling strategies to better understand how youth adjust and thrive following natural disaster.

The Use of Lesson Study Combined with Content Representation in the Planning of Physics Lessons During Field Practice to Develop Pedagogical Content Knowledge

NASA Astrophysics Data System (ADS)

Juhler, Martin Vogt

2016-08-01

Recent research, both internationally and in Norway, has clearly expressed concerns about missing connections between subject-matter knowledge, pedagogical competence and real-life practice in schools. This study addresses this problem within the domain of field practice in teacher education, studying pre-service teachers' planning of a Physics lesson. Two means of intervention were introduced. The first was lesson study, which is a method for planning, carrying out and reflecting on a research lesson in detail with a learner and content-centered focus. This was used in combination with a second means, content representations, which is a systematic tool that connects overall teaching aims with pedagogical prompts. Changes in teaching were assessed through the construct of pedagogical content knowledge (PCK). A deductive coding analysis was carried out for this purpose. Transcripts of pre-service teachers' planning of a Physics lesson were coded into four main PCK categories, which were thereafter divided into 16 PCK sub-categories. The results showed that the intervention affected the pre-service teachers' potential to start developing PCK. First, they focused much more on categories concerning the learners. Second, they focused far more uniformly in all of the four main categories comprising PCK. Consequently, these differences could affect their potential to start developing PCK.

NASA 1990 Multisensor Airborne Campaigns (MACs) for ecosystem and watershed studies

NASA Technical Reports Server (NTRS)

Wickland, Diane E.; Asrar, Ghassem; Murphy, Robert E.

1991-01-01

The Multisensor Airborne Campaign (MAC) focus within NASA's former Land Processes research program was conceived to achieve the following objectives: to acquire relatively complete, multisensor data sets for well-studied field sites, to add a strong remote sensing science component to ecology-, hydrology-, and geology-oriented field projects, to create a research environment that promotes strong interactions among scientists within the program, and to more efficiently utilize and compete for the NASA fleet of remote sensing aircraft. Four new MAC's were conducted in 1990: the Oregon Transect Ecosystem Research (OTTER) project along an east-west transect through central Oregon, the Forest Ecosystem Dynamics (FED) project at the Northern Experimental Forest in Howland, Maine, the MACHYDRO project in the Mahantango Creek watershed in central Pennsylvania, and the Walnut Gulch project near Tombstone, Arizona. The OTTER project is testing a model that estimates the major fluxes of carbon, nitrogen, and water through temperate coniferous forest ecosystems. The focus in the project is on short time-scale (days-year) variations in ecosystem function. The FED project is concerned with modeling vegetation changes of forest ecosystems using remotely sensed observations to extract biophysical properties of forest canopies. The focus in this project is on long time-scale (decades to millenia) changes in ecosystem structure. The MACHYDRO project is studying the role of soil moisture and its regulating effects on hydrologic processes. The focus of the study is to delineate soil moisture differences within a basin and their changes with respect to evapotranspiration, rainfall, and streamflow. The Walnut Gulch project is focused on the effects of soil moisture in the energy and water balance of arid and semiarid ecosystems and their feedbacks to the atmosphere via thermal forcing.

Focused feasibility study for surface soil at the main pits and pushout area, J-field toxic burning pits area, Aberdeen Proving Ground, Maryland

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

Patton, T.; Benioff, P.; Biang, C.

1996-06-01

The Environmental Management Division of Aberdeen Proving Ground (APG), Maryland, is conducting a remedial investigation and feasibility study of the J-Field area at APG pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act, as amended (CERCLA). J-Field is located within the Edgewood Area of APG in Harford County, Maryland. Since World War II, activities in the Edgewood Area have included the development, manufacture, testing, and destruction of chemical agents and munitions. These materials were destroyed at J-Field by open burning/open detonation. Portions of J-Field continue to be used for the detonation and disposal of unexploded ordnance (UXO) by openmore » burning/open detonation under authority of the Resource Conservation and Recovery Act.« less

Interaction of an electron with coherent dipole radiation: Role of convergence and anti-dephasing

NASA Astrophysics Data System (ADS)

Robinson, A. P. L.; Arefiev, A. V.

2018-05-01

The impact of longitudinal electric fields that are present in intense focusing and defocusing electromagnetic pulses on electron acceleration is investigated. These fields are typically much weaker than the transverse fields, but it is shown that they can have a profound effect on electron energy gain. It is shown that the longitudinal electric field of a defocusing pulse is directed backward along the trajectory of an accelerated electron, which leads to a continuous net energy gain. At the same time, the effect of the transverse oscillating electric field in a defocusing pulse is to reduce the electron energy over multiple oscillations. In contrast to a well-known interaction with a plane wave, the electron is able to retain a substantial amount of energy following its interaction with a defocusing pulse. The roles of the transverse and longitudinal electric fields are reversed in a focusing pulse, which leads to a reduction in the energy retention. The present analysis underscores the importance of relatively weak oscillating electric fields in focusing and defocusing pulses.

Testing a two-scale focused conservation strategy for reducing phosphorus and sediment loads from agricultural watersheds

USGS Publications Warehouse

Carvin, Rebecca; Good, Laura W.; Fitzpatrick, Faith A.; Diehl, Curt; Songer, Katherine; Meyer, Kimberly J.; Panuska, John C.; Richter, Steve; Whalley, Kyle

2018-01-01

This study tested a focused strategy for reducing phosphorus (P) and sediment loads in agricultural streams. The strategy involved selecting small watersheds identified as likely to respond relatively quickly, and then focusing conservation practices on high-contributing fields within those watersheds. Two 5,000 ha (12,360 ac) watersheds in the Driftless Area of south central Wisconsin, previously ranked in the top 6% of similarly sized Wisconsin watersheds for expected responsiveness to conservation efforts to reduce high P and sediment loads, were chosen for the study. The stream outlets from both watersheds were monitored from October of 2006 through September of 2016 for streamflow and concentrations of sediment, total P, and, beginning in October of 2009, total dissolved P. Fields and pastures having the highest potential P delivery to the streams in each watershed were identified using the Wisconsin P Index (Good et al. 2012). After three years of baseline monitoring (2006 to 2009), farmers implemented both field- and farm-based conservation practices in one watershed (treatment) as a means to reduce sediment and P inputs to the stream from the highest contributing areas, whereas there were no out-of-the-ordinary conservation efforts in the second watershed (control). Implementation occurred primarily in 2011 and 2012. In the four years following implementation of conservation practices (2013 through 2016), there was a statistically significant reduction in storm-event suspended sediment loads in the treatment watershed compared to the control watershed when the ground was not frozen (p = 0.047). While there was an apparent reduction in year-round suspended sediment event loads, it was not statistically significant at the 95% confidence level (p = 0.15). Total P loads were significantly reduced for runoff events (p < 0.01) with a median reduction of 50%. Total P and total dissolved P concentrations for low-flow conditions were also significantly reduced (p < 0.01) compared to the control watershed. This study demonstrated that a strategy that first identifies watersheds likely to respond to conservation efforts and then focuses implementation on relatively high-contributing fields within those watersheds can be successful in reducing stream P concentrations and loads.

Migration-related detention centers: the challenges of an ecological perspective with a focus on justice.

PubMed

Esposito, Francesca; Ornelas, José; Arcidiacono, Caterina

2015-06-06

In recent years, border control and migration-related detention have become increasingly widespread practices affecting the lives of undocumented migrants, their families, and communities at large. In spite of the concern within academia, few studies have directly witnessed the life and experiences of people confined to migration-related detention centers. In the medical and psychological fields, a considerable body of research has demonstrated the pathogenic nature of detention in terms of mental health, showing an association between length of detention and severity of distress. Nevertheless, it was limited to the assessment of individuals' clinical consequences, mainly focusing on asylum seekers. There currently exists a need to adopt an ecological perspective from which to study detained migrants' experiences as context-dependent, and influenced by power inequalities. This paper addresses this gap. Drawing upon advances in community psychology, we illustrate an ecological framework for the study of migration-related detention contexts, and their effects on the lives of detained migrants and all people exposed to them. Making use of existing literature, Kelly's four principles (interdependence, cycling of resources, adaptation, succession) are analyzed at multiple ecological levels (personal, interpersonal, organizational, communal), highlighting implications for future research in this field. A focus on justice, as a key-dimension of analysis, is also discussed. Wellbeing is acknowledged as a multilevel, dynamic, and value-dependent phenomenon. In presenting this alternative framework, the potential for studying migration-related detention through an ecological lens is highlighted, pointing the way for future fields of study. We argue that ecological multilevel analyses, conceptualized in terms of interdependent systems and with a focus on justice, can enhance the comprehension of the dynamics at play in migration-related detention centers, providing an effective tool to address the multi-level challenges of doing research within them. Furthermore, they can contribute to the development of policies and practices concerned with health, equality, and human rights of all people exposed to migration-related detention. Consistent with these assumptions, empirical studies adopting such a framework are strongly encouraged. These studies should use mixed and multi-method culturally situated designs, based on the development of collaborative and empowering relationships with participants. Ethnographic approaches are recommended.

Wide-field two-photon microscopy with temporal focusing and HiLo background rejection

NASA Astrophysics Data System (ADS)

Yew, Elijah Y. S.; Choi, Heejin; Kim, Daekeun; So, Peter T. C.

2011-03-01

Scanningless depth-resolved microscopy is achieved through spatial-temporal focusing and has been demonstrated previously. The advantage of this method is that a large area may be imaged without scanning resulting in higher throughput of the imaging system. Because it is a widefield technique, the optical sectioning effect is considerably poorer than with conventional spatial focusing two-photon microscopy. Here we propose wide-field two-photon microscopy based on spatio-temporal focusing and employing background rejection based on the HiLo microscope principle. We demonstrate the effects of applying HiLo microscopy to widefield temporally focused two-photon microscopy.

Influencing attitudes toward science through field experiences in biology

NASA Astrophysics Data System (ADS)

Carpenter, Deborah Mcintyre

The purpose of this study was to determine how student attitudes toward science are influenced by field experiences in undergraduate biology courses. The study was conducted using two institutions of higher education including a 2-year lower-level and a 2-year upper-level institution. Data were collected through interviews with student participants, focus group discussions, students' journal entries, and field notes recorded by the researcher during the field activities. Photographs and video recordings were also used as documentation sources. Data were collected over a period of 34 weeks. Themes that emerged from the qualitative data included students' beliefs that field experiences (a) positively influence student motivation to learn, (b) increase student ability to learn the concepts being taught, and (c) provide opportunities for building relationships and for personal growth. The findings of the study reinforce the importance of offering field-study programs at the undergraduate level to allow undergraduate students the opportunity to experience science activities in a field setting. The research study was framed by the behavioral and developmental theories of attitude and experience including the Theory of Planned Behavior (Ajzen, 1991) and the Theory of Experiential Learning (Kolb, 1984).

Collective field accelerator

DOEpatents

Luce, John S.

1978-01-01

A collective field accelerator which operates with a vacuum diode and utilizes a grooved cathode and a dielectric anode that operates with a relativistic electron beam with a .nu./.gamma. of .about. 1, and a plurality of dielectric lenses having an axial magnetic field thereabout to focus the collectively accelerated electrons and ions which are ejected from the anode. The anode and lenses operate as unoptimized r-f cavities which modulate and focus the beam.

Light field image denoising using a linear 4D frequency-hyperfan all-in-focus filter

NASA Astrophysics Data System (ADS)

Dansereau, Donald G.; Bongiorno, Daniel L.; Pizarro, Oscar; Williams, Stefan B.

2013-02-01

Imaging in low light is problematic as sensor noise can dominate imagery, and increasing illumination or aperture size is not always effective or practical. Computational photography offers a promising solution in the form of the light field camera, which by capturing redundant information offers an opportunity for elegant noise rejection. We show that the light field of a Lambertian scene has a 4D hyperfan-shaped frequency-domain region of support at the intersection of a dual-fan and a hypercone. By designing and implementing a filter with appropriately shaped passband we accomplish denoising with a single all-in-focus linear filter. Drawing examples from the Stanford Light Field Archive and images captured using a commercially available lenselet- based plenoptic camera, we demonstrate that the hyperfan outperforms competing methods including synthetic focus, fan-shaped antialiasing filters, and a range of modern nonlinear image and video denoising techniques. We show the hyperfan preserves depth of field, making it a single-step all-in-focus denoising filter suitable for general-purpose light field rendering. We include results for different noise types and levels, over a variety of metrics, and in real-world scenarios. Finally, we show that the hyperfan's performance scales with aperture count.

Simulations of nonlinear continuous wave pressure fields in FOCUS

NASA Astrophysics Data System (ADS)

Zhao, Xiaofeng; Hamilton, Mark F.; McGough, Robert J.

2017-03-01

The Khokhlov - Zabolotskaya - Kuznetsov (KZK) equation is a parabolic approximation to the Westervelt equation that models the effects of diffraction, attenuation, and nonlinearity. Although the KZK equation is only valid in the far field of the paraxial region for mildly focused or unfocused transducers, the KZK equation is widely applied in medical ultrasound simulations. For a continuous wave input, the KZK equation is effectively modeled by the Bergen Code [J. Berntsen, Numerical Calculations of Finite Amplitude Sound Beams, in M. F. Hamilton and D. T. Blackstock, editors, Frontiers of Nonlinear Acoustics: Proceedings of 12th ISNA, Elsevier, 1990], which is a finite difference model that utilizes operator splitting. Similar C++ routines have been developed for FOCUS, the `Fast Object-Oriented C++ Ultrasound Simulator' (http://www.egr.msu.edu/˜fultras-web) to calculate nonlinear pressure fields generated by axisymmetric flat circular and spherically focused ultrasound transducers. This new routine complements an existing FOCUS program that models nonlinear ultrasound propagation with the angular spectrum approach [P. T. Christopher and K. J. Parker, J. Acoust. Soc. Am. 90, 488-499 (1991)]. Results obtained from these two nonlinear ultrasound simulation approaches are evaluated and compared for continuous wave linear simulations. The simulation results match closely in the farfield of the paraxial region, but the results differ in the nearfield. The nonlinear pressure field generated by a spherically focused transducer with a peak surface pressure of 0.2MPa radiating in a lossy medium with β = 3.5 is simulated, and the computation times are also evaluated. The nonlinear simulation results demonstrate acceptable agreement in the focal zone. These two related nonlinear simulation approaches are now included with FOCUS to enable convenient simulations of nonlinear pressure fields on desktop and laptop computers.

Three-Dimensional Simulations of Electron Beams Focused by Periodic Permanent Magnets

NASA Technical Reports Server (NTRS)

Kory, Carol L.

1999-01-01

A fully three-dimensional (3D) model of an electron beam focused by a periodic permanent magnet (PPM) stack has been developed. First, the simulation code MAFIA was used to model a PPM stack using the magnetostatic solver. The exact geometry of the magnetic focusing structure was modeled; thus, no approximations were made regarding the off-axis fields. The fields from the static solver were loaded into the 3D particle-in-cell (PIC) solver of MAFIA where fully 3D behavior of the beam was simulated in the magnetic focusing field. The PIC solver computes the time-integration of electromagnetic fields simultaneously with the time integration of the equations of motion of charged particles that move under the influence of those fields. Fields caused by those moving charges are also taken into account; thus, effects like space charge and magnetic forces between particles are fully simulated. The electron beam is simulated by a number of macro-particles. These macro-particles represent a given charge Q amounting to that of several million electrons in order to conserve computational time and memory. Particle motion is unrestricted, so particle trajectories can cross paths and move in three dimensions under the influence of 3D electric and magnetic fields. Correspondingly, there is no limit on the initial current density distribution of the electron beam, nor its density distribution at any time during the simulation. Simulation results including beam current density, percent ripple and percent transmission will be presented, and the effects current, magnetic focusing strength and thermal velocities have on beam behavior will be demonstrated using 3D movies showing the evolution of beam characteristics in time and space. Unlike typical beam optics models, this 3D model allows simulation of asymmetric designs such as non- circularly symmetric electrostatic or magnetic focusing as well as the inclusion of input/output couplers.

The Integrated Reader: Literature and EE.

ERIC Educational Resources Information Center

Hage, Steve; Daniels, Rosalie

1996-01-01

Presents a selection of thematic units focusing on the environment that integrate literature, outdoor education, field studies, and research on current environmental issues. These units are part of a program offered at the School of Environmental Studies in Apple Valley, Minnesota. Authors include Thoreau, Camus, Orwell, Hemingway, Sophocles, and…

Following Footsteps: ECD Tracer Studies.

ERIC Educational Resources Information Center

Smale, Jim, Editor

2002-01-01

This document consists of the single 2002 issue of The Bernard van Leer Foundation's "Early Childhood Matters," a periodical addressed to practitioners in the field of early childhood education and including information on projects funded by the Foundation. Articles in this issue focus on early childhood development tracer studies of…

Communications and Media: Constructing a Cross-Discipline.

ERIC Educational Resources Information Center

Gordon, George N.

The contents of this book focus on various aspects of studies in communications, examining relevant criteria for their disciplined study, evaluating present research and criticism, and suggesting future directions of inquiry in the field of communications. Part one concerns the technology, viewpoints, and categories of communications; part two…

New operating strategies for molten salt in line focusing solar fields - Daily drainage and solar receiver preheating

NASA Astrophysics Data System (ADS)

Eickhoff, Martin; Meyer-Grünefeldt, Mirko; Keller, Lothar

2016-05-01

Nowadays molten salt is efficiently used in point concentrating solar thermal power plants. Line focusing systems still have the disadvantage of elevated heat losses at night because of active freeze protection of the solar field piping system. In order to achieve an efficient operation of line focusing solar power plants using molten salt, a new plant design and a novel operating strategy is developed for Linear Fresnel- and Parabolic Trough power plants. Daily vespertine drainage of the solar field piping and daily matutinal refilling of the solar preheated absorber tubes eliminate the need of nocturnal heating of the solar field and reduce nocturnal heat losses to a minimum. The feasibility of this new operating strategy with all its sub-steps has been demonstrated experimentally.

The neuroscience of psychological treatments.

PubMed

Barlow, David H

2014-11-01

The series of articles in this issue of Behavior Research and Therapy presages a new field of translational research that could be called "the neuroscience of psychological treatments". After a brief retrospective on the origins and promise of this focus of study several cautions are adumbrated. As in any new field of scientific endeavor, close collaboration among stakeholders with interest in this field and the integration of a healthy scientific skepticism will best ensure the continued development of ever more powerful psychological treatments. Copyright © 2014 Elsevier Ltd. All rights reserved.

Treatment envelope evaluation in transcranial magnetic resonance-guided focused ultrasound utilizing 3D MR thermometry

PubMed Central

2014-01-01

Background Current clinical targets for transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) are all located close to the geometric center of the skull convexity, which minimizes challenges related to focusing the ultrasound through the skull bone. Non-central targets will have to be reached to treat a wider variety of neurological disorders and solid tumors. Treatment envelope studies utilizing two-dimensional (2D) magnetic resonance (MR) thermometry have previously been performed to determine the regions in which therapeutic levels of FUS can currently be delivered. Since 2D MR thermometry was used, very limited information about unintended heating in near-field tissue/bone interfaces could be deduced. Methods In this paper, we present a proof-of-concept treatment envelope study with three-dimensional (3D) MR thermometry monitoring of FUS heatings performed in a phantom and a lamb model. While the moderate-sized transducer used was not designed for transcranial geometries, the 3D temperature maps enable monitoring of the entire sonication field of view, including both the focal spot and near-field tissue/bone interfaces, for full characterization of all heating that may occur. 3D MR thermometry is achieved by a combination of k-space subsampling and a previously described temporally constrained reconstruction method. Results We present two different types of treatment envelopes. The first is based only on the focal spot heating—the type that can be derived from 2D MR thermometry. The second type is based on the relative near-field heating and is calculated as the ratio between the focal spot heating and the near-field heating. This utilizes the full 3D MR thermometry data achieved in this study. Conclusions It is shown that 3D MR thermometry can be used to improve the safety assessment in treatment envelope evaluations. Using a non-optimal transducer, it is shown that some regions where therapeutic levels of FUS can be delivered, as suggested by the first type of envelope, are not necessarily safely treated due to the amount of unintended near-field heating occurring. The results presented in this study highlight the need for 3D MR thermometry in tcMRgFUS. PMID:25343028

[Positive occupational health psychology: an introduction].

PubMed

Bakker, Arnold B; Rodríguez-Muñoz, Alfredo

2012-02-01

This article introduces the monographic section on Positive Occupational Health Psychology (POHP), presenting eight theoretical and empirical papers about diverse topics. Traditionally, research on occupational health has mainly been focused on causes of diseases and on identifying and preventing work factors related to worker's impaired health. However, this biased view may not provide a complete understanding of the mechanisms that lead to employee well-being and performance. We discuss the differences of POHP with similar constructs, and review reasons for its importance in the development of this field. Overall, the studies included in the monographic section show the usefulness of focusing on positive constructs, and present ideas and questions that we hope may help to further our progress in the field of POHP.

Super-resolution in a defocused plenoptic camera: a wave-optics-based approach.

PubMed

Sahin, Erdem; Katkovnik, Vladimir; Gotchev, Atanas

2016-03-01

Plenoptic cameras enable the capture of a light field with a single device. However, with traditional light field rendering procedures, they can provide only low-resolution two-dimensional images. Super-resolution is considered to overcome this drawback. In this study, we present a super-resolution method for the defocused plenoptic camera (Plenoptic 1.0), where the imaging system is modeled using wave optics principles and utilizing low-resolution depth information of the scene. We are particularly interested in super-resolution of in-focus and near in-focus scene regions, which constitute the most challenging cases. The simulation results show that the employed wave-optics model makes super-resolution possible for such regions as long as sufficiently accurate depth information is available.

Evolution of geodesic congruences in a gravitationally collapsing scalar field background

NASA Astrophysics Data System (ADS)

Shaikh, Rajibul; Kar, Sayan; DasGupta, Anirvan

2014-12-01

The evolution of timelike geodesic congruences in a spherically symmetric, nonstatic, inhomogeneous spacetime representing gravitational collapse of a massless scalar field is studied. We delineate how initial values of the expansion, rotation, and shear of a congruence, as well as the spacetime curvature, influence the global behavior and focusing properties of a family of trajectories. Under specific conditions, the expansion scalar is shown to exhibit a finite jump (from negative to positive value) before focusing eventually occurs. This nonmonotonic behavior of the expansion, observed in our numerical work, is successfully explained through an analysis of the equation for the expansion. Finally, we bring out the role of the metric parameters (related to nonstaticity and spatial inhomogeneity) in shaping the overall behavior of geodesic congruences.

Extracellular Vesicles as Biomarkers and Therapeutics in Dermatology: A Focus on Exosomes.

PubMed

McBride, Jeffrey D; Rodriguez-Menocal, Luis; Badiavas, Evangelos V

2017-08-01

Extracellular vesicles (exosomes, microvesicles, and apoptotic bodies) are ubiquitous in human tissues, circulation, and body fluids. Of these vesicles, exosomes are of growing interest among investigators across multiple fields, including dermatology. The characteristics of exosomes, their associated cargo (nucleic acids, proteins, and lipids), and downstream functions are vastly different, depending on the cell origin. Here, we review concepts in extracellular vesicle biology, with a focus on exosomes, highlighting recent studies in the field of dermatology. Furthermore, we highlight emerging technical issues associated with isolating and measuring exosomes. Extracellular vesicles, including exosomes, have immediate potential for serving as biomarkers and therapeutics in dermatology over the next decade. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

The UV Survey Mission Concept, CETUS

NASA Astrophysics Data System (ADS)

Heap, Sara; and the CETUS Team

2018-01-01

In March 2017, NASA selected CETUS for study of a Probe-class mission concept. W. Danchi is the CETUS PI, and S. Heap is the Science PI. CETUS is primarily a UV survey telescope to complement survey telescopes of the 2020’s including E-ROSITA, Subaru Hyper Suprime Cam and Prime-Focus Spectrograph, WFIRST, and the Square Kilometer Array. CETUS comprises a 1.5-m wide-field telescope and three science instruments: a wide-field (1045” on a side) far-UV and near-UV camera; a similarly wide-field near-UV multi-object spectrograph utilizing a next-generation micro-shutter array; and a single-object spectrograph with options of spectral region (far-UV or near-UV) and spectral resolving power (2,000 or 40,000). The survey instruments will operate simultaneously thereby producing wide-field images in the near-UV and far-UV and a spectrogram containing near-UV spectra of up to 100 sources free of spectral overlap and astronomical background. ln concert with other survey telescopes, CETUS will focus on understanding galaxy evolution at cosmic noon (z~1-2).

Modeling Intracochlear Magnetic Stimulation: A Finite-Element Analysis.

PubMed

Mukesh, S; Blake, D T; McKinnon, B J; Bhatti, P T

2017-08-01

This study models induced electric fields, and their gradient, produced by pulsatile current stimulation of submillimeter inductors for cochlear implantation. Using finite-element analysis, the lower chamber of the cochlea, scala tympani, is modeled as a cylindrical structure filled with perilymph bounded by tissue, bone, and cochlear neural elements. Single inductors as well as an array of inductors are modeled. The coil strength (~100 nH) and excitation parameters (peak current of 1-5 A, voltages of 16-20 V) are based on a formative feasibility study conducted by our group. In that study, intracochlear micromagnetic stimulation achieved auditory activation as measured through the auditory brainstem response in a feline model. With respect to the finite element simulations, axial symmetry of the inductor geometry is exploited to improve computation time. It is verified that the inductor coil orientation greatly affects the strength of the induced electric field and thereby the ability to affect the transmembrane potential of nearby neural elements. Furthermore, upon comparing an array of micro-inductors with a typical multi-site electrode array, magnetically excited arrays retain greater focus in terms of the gradient of induced electric fields. Once combined with further in vivo analysis, this modeling study may enable further exploration of the mechanism of magnetically induced, and focused neural stimulation.

Beyond Portfolios: Looking at Students' Projects as Teaching and Evaluation Devices.

ERIC Educational Resources Information Center

Sokolik, Maggi; Tillyer, Anthea

1992-01-01

Based on classroom experience, this article discusses the advantages of research project writing rather than "portfolio" writing. Projects are more focused and can prepare students for study in their field. (eight references) (KM)

Older Adults' Perceptions of Home Telehealth Services

PubMed Central

Brenčič, Maja Makovec; Trkman, Peter; de Leonni Stanonik, Mateja

2013-01-01

Abstract The success of home telemedicine depends on end-user adoption, which has been slow despite rapid advances in technological development. This study focuses on an examination of significant factors that may predict the successful adoption of home telemedicine services (HTS) among older adults. Based on previous studies in the fields of remote patient monitoring, assisted living technologies, and consumer health information technology acceptance, eight factors were identified as a framework for qualitative testing. Twelve focus groups were conducted with an older population living in both urban and rural environments. The results reveal seven predictors that play an important role in perceptions of HTS: perceived usefulness, effort expectancy, social influence, perceived security, computer anxiety, facilitating conditions, and physicians' opinion. The results provide important insights in the field of older adults' acceptance of HTS, with guidelines for the strategic planning, developing, and marketing of HTS for the graying market. PMID:23931702

Eyeballs in the Fridge: Sources of early interest in science

NASA Astrophysics Data System (ADS)

Maltese, Adam V.; Tai, Robert H.

2010-03-01

This paper examines the experiences reported by scientists and graduate students regarding the experiences that first engaged them in science. The interviews analysed for this paper come from Project Crossover, a mixed-methods study of the transition from graduate student to PhD scientist in the fields of chemistry and physics. This analysis involved review of 116 interviews collected from graduate students and scientists and focused on the timing, source, and nature of their earliest interest in science. The majority (65%) of participants reported that their interest in science began before middle school. Females were more likely to report that their interest was sparked by school-related activities, while most males recounted self-initiated activities. Our findings indicate that current policy efforts (which focus on high school science reform) to increase the numbers of students studying in the science fields, may be misguided.

Role of inhibitory control in modulating focal seizure spread.

PubMed

Liou, Jyun-You; Ma, Hongtao; Wenzel, Michael; Zhao, Mingrui; Baird-Daniel, Eliza; Smith, Elliot H; Daniel, Andy; Emerson, Ronald; Yuste, Rafael; Schwartz, Theodore H; Schevon, Catherine A

2018-05-10

Focal seizure propagation is classically thought to be spatially contiguous. However, distribution of seizures through a large-scale epileptic network has been theorized. Here, we used a multielectrode array, wide field calcium imaging, and two-photon calcium imaging to study focal seizure propagation pathways in an acute rodent neocortical 4-aminopyridine model. Although ictal neuronal bursts did not propagate beyond a 2-3-mm region, they were associated with hemisphere-wide field potential fluctuations and parvalbumin-positive interneuron activity outside the seizure focus. While bicuculline surface application enhanced contiguous seizure propagation, focal bicuculline microinjection at sites distant to the 4-aminopyridine focus resulted in epileptic network formation with maximal activity at the two foci. Our study suggests that both classical and epileptic network propagation can arise from localized inhibition defects, and that the network appearance can arise in the context of normal brain structure without requirement for pathological connectivity changes between sites.

Demographically Induced Variation in Students' Beliefs about Learning and Studying German.

ERIC Educational Resources Information Center

Chavez, Monika

1995-01-01

Examines how the demographic values of foreign travel, previous foreign-language learning, major field of study, and other factors affect students' beliefs about the study of German. The article focuses on student-perceived improvement in the four skills and cultural knowledge, student motivation, and the expected contributions of teachers and…

Educating for Leadership in a Divided Country: Educational Practices for a New Nigeria

ERIC Educational Resources Information Center

Aydin, Hasan

2013-01-01

This study reports on a 2011 qualitative field study conducted at the Nigerian Turkish International Colleges (NTICs) in Abuja, Nigeria. The study uses both in-depth interviews and small focus groups to elicit the lived experience of six identified groups of stakeholders (administrators, teachers, students, parents, Nigerian leaders, and…

Lewis Terman: Genetic Study of Genius--Elementary School Students

ERIC Educational Resources Information Center

Jolly, Jennifer L.

2008-01-01

Although the field of gifted education generally recognizes the foundational work of Lewis Terman, rarely does one stop to examine the details of his longitudinal study and their connection to present-day gifted education. This article reexamines the beginnings of Terman's longitudinal study with a focus on elementary-school-aged children.…

Connect Them Bones! An Interdisciplinary Study of Owl Pellets.

ERIC Educational Resources Information Center

Zipko, Stephen J.

1983-01-01

Discusses a field/laboratory study of the barn owl in which students collect and dissect owl pellets. Interdisciplinary lessons focus on eco-politics, reconstruction of owl prey skeletons, studies of predator-prey relationships, and construction/installation of nest boxes for owls and other birds. The unit begins and ends with an attitude…

Social Justice, Disability, and Rehabilitation Education

ERIC Educational Resources Information Center

Kelsey, Daniel; Smart, Julie F.

2012-01-01

The academic field and the professional practice of rehabilitation counseling focuses on one aspect of social justice, assisting individuals with disabilities to attain full community inclusion. Nonetheless, social justice focuses on many marginalized groups and in the related fields of counseling and psychology, those with disabilities are rarely…

Computational Investigation of Helical Traveling Wave Tube Transverse RF Field Forces

NASA Technical Reports Server (NTRS)

Kory, Carol L.; Dayton, James A.

1998-01-01

In a previous study using a fully three-dimensional (3D) helical slow-wave circuit cold- test model it was found, contrary to classical helical circuit analyses, that transverse FF electric fields have significant amplitudes compared with the longitudinal component. The RF fields obtained using this helical cold-test model have been scaled to correspond to those of an actual TWT. At the output of the tube, RF field forces reach 61%, 26% and 132% for radial, azimuthal and longitudinal components, respectively, compared to radial space charge forces indicating the importance of considering them in the design of electron beam focusing.

Resistance and internal electric field in cloud-to-ground lightning channel

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

Cen, Jianyong; Yuan, Ping, E-mail: yuanp@nwnu.edu.cn; Xue, Simin

2015-02-02

Cloud-to-ground lightning with six return strokes has been recorded by slitless spectrograph and the system of fast antenna and slow antenna. The physical parameters of the discharge channel have been obtained based on the combination of spectra and synchronous radiated electric field. The resistance and internal electric field of the channel are studied as the focus in this paper. The results show that the resistances per unit length of the lightning channel are in the order of 10{sup −2}–10{sup −1 }Ω/m and the internal electric field strengths are in the order of 10{sup 3 }V/m.

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.

Learning to Design WebQuests: An Exploration in Preservice Social Studies Education

ERIC Educational Resources Information Center

Bates, Alisa

2008-01-01

Effective uses of technology in social studies methods courses is an under-researched field. This study focused on the development of WebQuests to engage teacher candidate's exploration of the Internet as an authentic medium for inquiry in social studies education. Analysis of appropriateness of tasks in the WebQuests, depth of ideas and audience…

The Effect of Sedimentary Basins on Through-Passing Short-Period Surface Waves

NASA Astrophysics Data System (ADS)

Feng, L.; Ritzwoller, M. H.

2017-12-01

Surface waves propagating through sedimentary basins undergo elastic wave field complications that include multiple scattering, amplification, the formation of secondary wave fronts, and subsequent wave front healing. Unless these effects are accounted for accurately, they may introduce systematic bias to estimates of source characteristics, the inference of the anelastic structure of the Earth, and ground motion predictions for hazard assessment. Most studies of the effects of basins on surface waves have centered on waves inside the basins. In contrast, we investigate wave field effects downstream from sedimentary basins, with particular emphasis on continental basins and propagation paths, elastic structural heterogeneity, and Rayleigh waves at 10 s period. Based on wave field simulations through a recent 3D crustal and upper mantle model of East Asia, we demonstrate significant Rayleigh wave amplification downstream from sedimentary basins in eastern China such that Ms measurements obtained on the simulated wave field vary by more than a magnitude unit. We show that surface wave amplification caused by basins results predominantly from elastic focusing and that amplification effects produced through 3D basin models are reproduced using 2D membrane wave simulations through an appropriately defined phase velocity map. The principal characteristics of elastic focusing in both 2D and 3D simulations include (1) retardation of the wave front inside the basins; (2) deflection of the wave propagation direction; (3) formation of a high amplitude lineation directly downstream from the basin bracketed by two low amplitude zones; and (4) formation of a secondary wave front. Finally, by comparing the impact of elastic focusing with anelastic attenuation, we argue that on-continent sedimentary basins are expected to affect surface wave amplitudes more strongly through elastic focusing than through the anelastic attenuation.

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

Kavet, R.; Tell, R.A.

As the use of video display terminals (VDTs) has expanded, questions have been raised as to whether working at a VDT affects the risk of adverse pregnancy outcome. A particular focus for these questions has been the very low frequency (VLF) magnetic field produced by a VDT's horizontal deflection coil. VDTs also produce VLF electric fields, extremely low frequency (ELF) electric and magnetic fields, and static electric fields, Ten studies of pregnancy outcome in VDT operators have been conducted in six countries, and with one exception, none has concluded that magnetic fields from VDTs may predispose pregnant operators to spontaneousmore » abortion or congenital malformation. The epidemiologic studies conducted thus far do not provide a basis for concluding that VDT work and adverse pregnancy outcome are associated. Studies of fetal resorptions and malformations in rodents exposed to VLF magnetic fields have produced inconsistent findings. Two laboratories in Sweden that studied mice have reported positive results, one laboratory showing field-related malformations (but not resorptions) and the other showing field-related resorptions (but not malformations). Two Canadian laboratories have reported negative results in rats and mice. Studies of avian embryos have also yielded inconsistent results, but lacking a maternal-fetal placental interface, avian embryos are a questionable model for evaluating human reproductive risks. Finally, VLF electric and magnetic fields measured at the operator position are in compliance with field strength standards and guidelines that have been established around the world. 55 refs.« less

Improved alternating gradient transport and focusing of neutral molecules

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

Kalnins, Juris; Lambertson, Glen; Gould, Harvey

2001-12-02

Polar molecules, in strong-field seeking states, can be transported and focused by an alternating sequence of electric field gradients that focus in one transverse direction while defocusing in the other. We show by calculation and numerical simulation, how one may greatly improve the alternating gradient transport and focusing of molecules. We use a new optimized multipole lens design, a FODO lattice beam transport line, and lenses to match the beam transport line to the beam source and the final focus. We derive analytic expressions for the potentials, fields, and gradients that may be used to design these lenses. We describemore » a simple lens optimization procedure and derive the equations of motion for tracking molecules through a beam transport line. As an example, we model a straight beamline that transports a 560 m/s jet-source beam of methyl fluoride molecules 15 m from its source and focuses it to 2 mm diameter. We calculate the beam transport line acceptance and transmission, for a beam with velocity spread, and estimate the transmitted intensity for specified source conditions. Possible applications are discussed.« less

The effect of user's perceived presence and promotion focus on usability for interacting in virtual environments.

PubMed

Sun, Huey-Min; Li, Shang-Phone; Zhu, Yu-Qian; Hsiao, Bo

2015-09-01

Technological advance in human-computer interaction has attracted increasing research attention, especially in the field of virtual reality (VR). Prior research has focused on examining the effects of VR on various outcomes, for example, learning and health. However, which factors affect the final outcomes? That is, what kind of VR system design will achieve higher usability? This question remains largely. Furthermore, when we look at VR system deployment from a human-computer interaction (HCI) lens, does user's attitude play a role in achieving the final outcome? This study aims to understand the effect of immersion and involvement, as well as users' regulatory focus on usability for a somatosensory VR learning system. This study hypothesized that regulatory focus and presence can effectively enhance user's perceived usability. Survey data from 78 students in Taiwan indicated that promotion focus is positively related to user's perceived efficiency, whereas involvement and promotion focus are positively related to user's perceived effectiveness. Promotion focus also predicts user satisfaction and overall usability perception. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

SU-E-T-590: Optimizing Magnetic Field Strengths with Matlab for An Ion-Optic System in Particle Therapy Consisting of Two Quadrupole Magnets for Subsequent Simulations with the Monte-Carlo Code FLUKA

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

Baumann, K; Weber, U; Simeonov, Y

Purpose: Aim of this study was to optimize the magnetic field strengths of two quadrupole magnets in a particle therapy facility in order to obtain a beam quality suitable for spot beam scanning. Methods: The particle transport through an ion-optic system of a particle therapy facility consisting of the beam tube, two quadrupole magnets and a beam monitor system was calculated with the help of Matlab by using matrices that solve the equation of motion of a charged particle in a magnetic field and field-free region, respectively. The magnetic field strengths were optimized in order to obtain a circular andmore » thin beam spot at the iso-center of the therapy facility. These optimized field strengths were subsequently transferred to the Monte-Carlo code FLUKA and the transport of 80 MeV/u C12-ions through this ion-optic system was calculated by using a user-routine to implement magnetic fields. The fluence along the beam-axis and at the iso-center was evaluated. Results: The magnetic field strengths could be optimized by using Matlab and transferred to the Monte-Carlo code FLUKA. The implementation via a user-routine was successful. Analyzing the fluence-pattern along the beam-axis the characteristic focusing and de-focusing effects of the quadrupole magnets could be reproduced. Furthermore the beam spot at the iso-center was circular and significantly thinner compared to an unfocused beam. Conclusion: In this study a Matlab tool was developed to optimize magnetic field strengths for an ion-optic system consisting of two quadrupole magnets as part of a particle therapy facility. These magnetic field strengths could subsequently be transferred to and implemented in the Monte-Carlo code FLUKA to simulate the particle transport through this optimized ion-optic system.« less

Vortex focusing of ions produced in corona discharge.

PubMed

Kolomiets, Yuri N; Pervukhin, Viktor V

2013-06-15

Completeness of the ion transportation into an analytical path defines the efficiency of ionization analysis techniques. This is of particular importance for atmospheric pressure ionization sources like corona discharge, electrospray, ionization with radioactive ((3)H, (63)Ni) isotopes that produce nonuniform spatial distribution of sample ions. The available methods of sample ion focusing are either efficient at reduced pressure (~1Torr) or feature high sample losses. This paper deals with experimental research into atmospheric pressure focusing of unipolar (positive) ions using a highly swirled air stream with a well-defined vortex core. Effects of electrical fields from corona needle and inlet capillary of mass spectrometer on collection efficiency is considered. We used a corona discharge to produce an ionized unipolar sample. It is shown experimentally that with an electrical field barrier efficient transportation and focusing of an ionized sample are possible only when a metal plate restricting the stream and provided with an opening covered with a grid is used. This gives a five-fold increase of the transportation efficiency. It is shown that the electric field barrier in the vortex sampling region reduces the efficiency of remote ionized sample transportation two times. The difference in the efficiency of light ion focusing observed may be explained by a high mobility and a significant effect of the electric field barrier upon them. It is possible to conclude based on the experimental data that the presence of the field barrier narrows considerably (more than by one and half) the region of the vortex sample ion focusing. Copyright © 2013 Elsevier B.V. All rights reserved.

Positive Youth Action towards Climate Change

ERIC Educational Resources Information Center

Buttigieg, Karen; Pace, Paul

2013-01-01

This study focuses on the experiences of young people who are leaders of change in the environmental field. This study views environmental activism as a personal commitment towards pro-environmental behaviour. The motivations and challenges of such work are viewed as important to learn more not only about volunteering in environmental…

A Game of Thrones: Organising and Legitimising Knowledge through PISA Research

ERIC Educational Resources Information Center

Mølstad, Christina E.; Pettersson, Daniel; Forsberg, Eva

2017-01-01

This study investigates knowledge structures and scientific communication using bibliometric methods to explore scientific knowledge production and dissemination. The aim is to develop knowledge about this growing field by investigating studies using international large-scale assessment (ILSA) data, with a specific focus on those using Programme…

Emotional Readiness and Music Therapeutic Activities

ERIC Educational Resources Information Center

Drossinou-Korea, Maria; Fragkouli, Aspasia

2016-01-01

The purpose of this study is to understand the children's expression with verbal and nonverbal communication in the Autistic spectrum. We study the emotional readiness and the music therapeutic activities which exploit the elements of music. The method followed focused on the research field of special needs education. Assumptions on the parameters…

Veterans Education: Coming Home to the Community College Classroom

ERIC Educational Resources Information Center

Persky, Karen Rae

2010-01-01

The purpose of this study was to identify the needs of veterans who are community college students and to examine community college programs and services essential to meeting their needs. A qualitative case study design using interviews, observations, field notes, document reviews, a focus group, and a preinterview demographic questionnaire…

Outing the Imposter: A Study Exploring Imposter Phenomenon among Higher Education Faculty

ERIC Educational Resources Information Center

Hutchins, Holly M.

2015-01-01

Attention to faculty development, especially factors influencing faculty satisfaction and performance, has increased in the last decade. While a significant focus has been on contextual factors (i.e., tenure policies, mentoring, work-life integration), fewer studies have examined individual psychological factors especially in the field of human…

Baccalaureate Origins of Education Doctorates around the World.

ERIC Educational Resources Information Center

Bautista, Edna R.

This study focused on which countries (besides the United States) produced the most doctorates in the education field, based on data provided by the National Research Council. The study combined the baccalaureate origins of education doctorates with the rankings of countries, and considered each country's cultural, social, economic, and political…

ABCs of Diversifying Information Resources among Rice Smallholders of Ghana

ERIC Educational Resources Information Center

Misiko, M.; Halm, E.

2016-01-01

Purpose: We investigated how information resource diversification can enhance smallholder agricultural knowledge in Ghana. Design/Methodology/Approach: Study tools and methods were questionnaire survey (N = 200), focus group discussion (N = 1), in-depth interviews (N = 18) and field direct observation. Findings: This study shows there existed…

Evolution of Observation: Implementing Programmatic Change

ERIC Educational Resources Information Center

Bender-Slack, Delane A.; Young, Teresa

2013-01-01

In the study reported, we examine the evolution of preservice teacher observation, focusing on the essential nature of observation to preservice teachers' learning about teaching while in the field. The study was 3 years long, and it involved 79 preservice teachers during semester-long language arts methods courses in early childhood and…

Adolescent Thriving: The Role of Sparks, Relationships, and Empowerment

ERIC Educational Resources Information Center

Scales, Peter C.; Benson, Peter L.; Roehlkepartain, Eugene C.

2011-01-01

Although most social science research on adolescence emphasizes risks and challenges, an emergent field of study focuses on adolescent thriving. The current study extends this line of inquiry by examining the additive power of identifying and nurturing young people's "sparks," giving them "voice," and providing the relationships and opportunities…

Problem-Solving Studies in Mathematics. Monograph Series.

ERIC Educational Resources Information Center

Harvey, John G., Ed.; Romberg, Thomas A., Ed.

This monograph focuses on educational research on the processes and natures of problem-solving activities in mathematics. The first chapter presents an overview to both the field and the document itself. All of the studies reported reflect interrelated investigations carried out at the University of Madison-Wisconsin, as partial fulfillments of…

Citizenship as Social Studies Education. Bulletin 4.

ERIC Educational Resources Information Center

Barth, James L., Ed.

This collection of seven papers focused on the topic citizenship as a part of social studies education. The titles of the papers are: "Old Glory, the Constitution, and Responsible Americanism: Elementary School Citizenship Education During World War II" (Sherry L. Field); "Shaping Model Citizens through Rituals of Good Manners: Examples from…

Emergent Literacy: A Polyphony of Perspectives. CIERA Report.

ERIC Educational Resources Information Center

Yaden, David B., Jr.; Rowe, Deborah W.; MacGillivray, Laurie

This paper reviews current developments in the field of emergent literacy (the study of reading and writing behaviors that develop into conventional literacy). The review includes studies that look at preschoolers' emerging literacy in homes, day-care environments, and kindergartens and that focus on children's development of literacy knowledge…

Disability Life Writing and the Politics of Knowing

ERIC Educational Resources Information Center

Ferri, Beth A.

2011-01-01

Background/Context: Scholars in disability studies in education, like scholars in other critical fields of inquiry, increasingly draw on a more interdisciplinary range of texts in their research and teaching, including art, fiction, film, and autobiography. Purpose/Objective/Research Question/Focus of Study: The author asserts that contemporary…

Suburban District Leaders' Perception of Their Practices

ERIC Educational Resources Information Center

Garcia France, Roxanne

2013-01-01

In the field of district leadership, most studies focus only on the context and conditions existing in large urban districts in need of reform. This study examined whether district leadership practices have applicability to district leaders working within the suburban context. In addition, it determined whether district conditions (i.e., district…

Research Designs and Methods in Self-Assessment Studies: A Content Analysis

ERIC Educational Resources Information Center

Pastore, Serafina

2017-01-01

This paper focuses on self-assessment studies in the higher education field. In the assessment for learning perspective, self-assessment is related to reflection, metacognition, and self-regulation: all these aspects are considered as fundamental prerequisites for students' future professional development. Despite the recognition of…

A Focused Ethnographic Study of Sri Lankan Government Field Veterinarians’ Decision Making about Diagnostic Laboratory Submissions and Perceptions of Surveillance

PubMed Central

Sawford, Kate; Vollman, Ardene Robinson; Stephen, Craig

2012-01-01

The global public health community is facing the challenge of emerging infectious diseases. Historically, the majority of these diseases have arisen from animal populations at lower latitudes where many nations experience marked resource constraints. In order to minimize the impact of future events, surveillance of animal populations will need to enable prompt event detection and response. Many surveillance systems targeting animals rely on veterinarians to submit cases to a diagnostic laboratory or input clinical case data. Therefore understanding veterinarians’ decision-making process that guides laboratory case submission and their perceptions of infectious disease surveillance is foundational to interpreting disease patterns reported by laboratories and engaging veterinarians in surveillance initiatives. A focused ethnographic study was conducted with twelve field veterinary surgeons that participated in a mobile phone-based surveillance pilot project in Sri Lanka. Each participant agreed to an individual in-depth interview that was recorded and later transcribed to enable thematic analysis of the interview content. Results found that field veterinarians in Sri Lanka infrequently submit cases to laboratories – so infrequently that common case selection principles could not be described. Field veterinarians in Sri Lanka have a diagnostic process that operates independently of laboratories. Participants indicated a willingness to take part in surveillance initiatives, though they highlighted a need for incentives that satisfy a range of motivations that vary among field veterinarians. This study has implications for the future of animal health surveillance, including interpretation of disease patterns reported, system design and implementation, and engagement of data providers. PMID:23133542

Keck Geology Consortium Lava Project: Undergraduate Research Linking Natural and Experimental Basaltic Lava Flows

NASA Astrophysics Data System (ADS)

Karson, J. A.; Hazlett, R. W.; Wysocki, R.; Bromfield, M. E.; Browne, N. C.; Davis, N. C.; Pelland, C. G.; Rowan, W. L.; Warner, K. A.

2014-12-01

Undergraduate students in the Keck Geology Consortium Lava Project participated in a month-long investigation of features of basaltic lava flows from two very different perspectives. The first half of the project focused on field relations in basaltic lava flows from the 1984 Krafla Fires eruption in northern Iceland. Students gained valuable experience in the collection of observations and samples in the field leading to hypotheses for the formation of selected features related to lava flow dynamics. Studies focused on a wide range of features including: morphology and heat loss in lava tubes (pyroducts), growth and collapse of lava ponds and overflow deposits, textural changes of lava falls (flow over steep steps), spaced spatter cones from flows over wet ground, and anisotropy of magnetic susceptibility related to flow kinematics. In the second half of the program students designed, helped execute, documented, and analyzed features similar to those they studied in the field with large-scale (50-250 kg) basaltic lava flows created in the Syracuse University Lava Project (http://lavaproject.syr.edu). Data collected included video from multiple perspectives, infrared thermal (FLIR) images, still images, detailed measurements of flow dimensions and rates, and samples for textural and magnetic analyses. Experimental lava flow features provided critical tests of hypotheses generated in the field and a refined understanding of the behavior and final morphology of basaltic lava flows. The linked field and experimental studies formed the basis for year-long independent research projects under the supervision of their faculty mentors, leading to senior theses at the students' respective institutions.

Sarah was a butch: sexual identity, gender practices, and Sarah's place as mother in the Jewish National Pantheon.

PubMed

Kalev, Henriette Dahan

2012-01-01

Three fields of discourse regarding a masculine-like woman connect at a point that the queer field calls intersex, medical practice calls a sexual disorder, and rabbinic literature terms aylonit. The queer discursive field focuses on the freedom to choose an identity, but not the freedom from choosing one. The medical field focuses on sexual practice as the source of determining "normal" sexuality. In the discursive field of Jewish law there are no demands, because the Halakhic authority determines gender identity on behalf of the individual, maintaining ambiguity. Copyright © Taylor & Francis Group, LLC

Longitudinal terahertz wave generation from an air plasma filament induced by a femtosecond laser

NASA Astrophysics Data System (ADS)

Minami, Yasuo; Kurihara, Takayuki; Yamaguchi, Keita; Nakajima, Makoto; Suemoto, Tohru

2013-04-01

We have generated and detected a longitudinally polarized (Z-polarized) terahertz (THz) wave by focusing a conically propagating THz beam generated from a plasma filament induced by a femtosecond laser pulse. In the experiment, we observed a radially polarized field in a collimated region and Z-polarized field at focus in the time domain. The maximum value of the Z-polarized THz electric field reached 1.0 kV/cm. It was also quantitatively discussed about the Z-polarized field and the radial field at the focal point. We expect this technique to find application in THz time domain spectroscopy.

What is biomedical informatics?

PubMed Central

Bernstam, Elmer V.; Smith, Jack W.; Johnson, Todd R.

2009-01-01

Biomedical informatics lacks a clear and theoretically grounded definition. Many proposed definitions focus on data, information, and knowledge, but do not provide an adequate definition of these terms. Leveraging insights from the philosophy of information, we define informatics as the science of information, where information is data plus meaning. Biomedical informatics is the science of information as applied to or studied in the context of biomedicine. Defining the object of study of informatics as data plus meaning clearly distinguishes the field from related fields, such as computer science, statistics and biomedicine, which have different objects of study. The emphasis on data plus meaning also suggests that biomedical informatics problems tend to be difficult when they deal with concepts that are hard to capture using formal, computational definitions. In other words, problems where meaning must be considered are more difficult than problems where manipulating data without regard for meaning is sufficient. Furthermore, the definition implies that informatics research, teaching, and service should focus on biomedical information as data plus meaning rather than only computer applications in biomedicine. PMID:19683067

Bipartite graphs in systems biology and medicine: a survey of methods and applications.

PubMed

Pavlopoulos, Georgios A; Kontou, Panagiota I; Pavlopoulou, Athanasia; Bouyioukos, Costas; Markou, Evripides; Bagos, Pantelis G

2018-04-01

The latest advances in high-throughput techniques during the past decade allowed the systems biology field to expand significantly. Today, the focus of biologists has shifted from the study of individual biological components to the study of complex biological systems and their dynamics at a larger scale. Through the discovery of novel bioentity relationships, researchers reveal new information about biological functions and processes. Graphs are widely used to represent bioentities such as proteins, genes, small molecules, ligands, and others such as nodes and their connections as edges within a network. In this review, special focus is given to the usability of bipartite graphs and their impact on the field of network biology and medicine. Furthermore, their topological properties and how these can be applied to certain biological case studies are discussed. Finally, available methodologies and software are presented, and useful insights on how bipartite graphs can shape the path toward the solution of challenging biological problems are provided.

Performance oriented guidance for Mississippi chip seals - volume II.

DOT National Transportation Integrated Search

2013-12-01

A laboratory and field study was conducted related to long term chip seal performance. This reports primary : objective was to initiate development of a long term performance (LTP) test protocol for chip seals focused on : aggregate retention. Key...

Geothermal industry assessment

NASA Astrophysics Data System (ADS)

1980-07-01

Focus is on industry structure, corporate activities and strategies, and detailed analysis of the technological, economic, financial, and institutional issues important to government policy formulation. The study is based principally on confidential interviews and with executives of 75 companies active in the field.

An alternative approach to depth of field which avoids the blur circle and uses the pixel pitch

NASA Astrophysics Data System (ADS)

Schuster, Norbert

2015-09-01

Modern thermal imaging systems apply more and more uncooled detectors. High volume applications work with detectors which have a reduced pixel count (typical between 200x150 and 640x480). This shrinks the application of modern image treatment procedures like wave front coding. On the other hand side, uncooled detectors demand lenses with fast F-numbers near 1.0. Which are the limits on resolution if the target to analyze changes its distance to the camera system? The aim to implement lens arrangements without any focusing mechanism demands a deeper quantification of the Depth of Field problem. The proposed Depth of Field approach avoids the classic "accepted image blur circle". It bases on a camera specific depth of focus which is transformed in the object space by paraxial relations. The traditional RAYLEIGH's -criterion bases on the unaberrated Point Spread Function and delivers a first order relation for the depth of focus. Hence, neither the actual lens resolution neither the detector impact is considered. The camera specific depth of focus respects a lot of camera properties: Lens aberrations at actual F-number, detector size and pixel pitch. The through focus MTF is the base of the camera specific depth of focus. It has a nearly symmetric course around the maximum of sharp imaging. The through focus MTF is considered at detector's Nyquist frequency. The camera specific depth of focus is this the axial distance in front and behind of sharp image plane where the through focus MTF is <0.25. This camera specific depth of focus is transferred in the object space by paraxial relations. It follows a general applicable Depth of Field diagram which could be applied to lenses realizing a lateral magnification range -0.05…0. Easy to handle formulas are provided between hyperfocal distance and the borders of the Depth of Field in dependence on sharp distances. These relations are in line with the classical Depth of Field-theory. Thermal pictures, taken by different IR-camera cores, illustrate the new approach. The quite often requested graph "MTF versus distance" choses the half Nyquist frequency as reference. The paraxial transfer of the through focus MTF in object space distorts the MTF-curve: hard drop at closer distances than sharp distance, smooth drop at further distances. The formula of a general Diffraction-Limited-Through-Focus-MTF (DLTF) is deducted. Arbitrary detector-lens combinations could be discussed. Free variables in this analysis are waveband, aperture based F-number (lens) and pixel pitch (detector). The DLTF- discussion provides physical limits and technical requirements. The detector development with pixel pitches smaller than captured wavelength in the LWIR-region generates a special challenge for optical design.

Secondary Science Teachers' Beliefs and Persistence: A Longitudinal Mixed-Methods Study

ERIC Educational Resources Information Center

Wong, Sissy S.; Luft, Julie A.

2015-01-01

While many studies focus on why teachers leave the classroom, there remains a need to study why teachers persist in teaching. One area to study is the beliefs of teachers, which may impact persistence in the field. This 5-year mixed-methods study explored whether 35 beginning secondary science teachers' beliefs were related to their persistence in…

Relative Contributions of Geothermal Pumping and Long-Term Earthquake Rate to Seismicity at California Geothermal Fields

NASA Astrophysics Data System (ADS)

Weiser, D. A.; Jackson, D. D.

2015-12-01

In a tectonically active area, a definitive discrimination between geothermally-induced and tectonic earthquakes is difficult to achieve. We focus our study on California's 11 major geothermal fields: Amedee, Brawley, Casa Diablo, Coso, East Mesa, The Geysers, Heber, Litchfield, Salton Sea, Susanville, and Wendel. The Geysers geothermal field is the world's largest geothermal energy producer. California's Department of Oil Gas and Geothermal Resources provides field-wide monthly injection and production volumes for each of these sites, which allows us to study the relationship between geothermal pumping activities and seismicity. Since many of the geothermal fields began injecting and producing before nearby seismic stations were installed, we use smoothed seismicity since 1932 from the ANSS catalog as a proxy for tectonic earthquake rate. We examine both geothermal pumping and long-term earthquake rate as factors that may control earthquake rate. Rather than focusing only on the largest earthquake, which is essentially a random occurrence in time, we examine how M≥4 earthquake rate density (probability per unit area, time, and magnitude) varies for each field. We estimate relative contributions to the observed earthquake rate of M≥4 from both a long-term earthquake rate (Kagan and Jackson, 2010) and pumping activity. For each geothermal field, respective earthquake catalogs (NCEDC and SCSN) are complete above at least M3 during the test period (which we tailor to each site). We test the hypothesis that the observed earthquake rate at a geothermal site during the test period is a linear combination of the long-term seismicity and pumping rates. We use a grid search to determine the confidence interval of the weighting parameters.

Assessment of Wetland Ecosystem Condition across Landscape Regions-A multi-metric Approach. Part A. Ecological Integrity Assessment Overview and Field Study in Michigan and Indiana. and Part B. Ecological Integrity Assessment Protocols for Rapid Field Methods (L2)

EPA Science Inventory

Many ecosystem monitoring and assessment programs are expanding their focus to address changes in ecosystem condition. This is a challenging task, given the complexity of ecosystems and the changes they undergo in response to a variety of human activities and landscape alteration...

Nonlinear Relaxation in Population Dynamics

NASA Astrophysics Data System (ADS)

Cirone, Markus A.; de Pasquale, Ferdinando; Spagnolo, Bernardo

We analyze the nonlinear relaxation of a complex ecosystem composed of many interacting species. The ecological system is described by generalized Lotka-Volterra equations with a multiplicative noise. The transient dynamics is studied in the framework of the mean field theory and with random interaction between the species. We focus on the statistical properties of the asymptotic behaviour of the time integral of the ith population and on the distribution of the population and of the local field.

Karl Schwarzschild's investigations of `out-of-focus photometry' between 1897 and 1899 at Kuffner Observatory in Vienna

NASA Astrophysics Data System (ADS)

Habison, Peter

From 1897 to 1899 Karl Schwarzschild worked at the Kuffner Observatory in Vienna. During these years he developed new measuring techniques in the field of photographic photometry, where he studied particularly the quantitative determination of the departure from the reciprocity law during photographic exposure. This paper concentrates on Schwarzschild's early work in this field and gives an overview of his important Viennese years.

Evolution of the magnetic field generated by the Kelvin-Helmholtz instability

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

Modestov, M.; Bychkov, V.; Brodin, G.

2014-07-15

The Kelvin-Helmholtz instability in an ionized plasma is studied with a focus on the magnetic field generation via the Biermann battery (baroclinic) mechanism. The problem is solved by using direct numerical simulations of two counter-directed flows in 2D geometry. The simulations demonstrate the formation of eddies and their further interaction and merging resulting in a large single vortex. In contrast to general belief, it is found that the instability generated magnetic field may exhibit significantly different structures from the vorticity field, despite the mathematically identical equations controlling the magnetic field and vorticity evolution. At later stages of the nonlinear instabilitymore » development, the magnetic field may keep growing even after the hydrodynamic vortex strength has reached its maximum and started decaying due to dissipation.« less

The generation of gravitational waves. I - Weak-field sources

NASA Technical Reports Server (NTRS)

Thorne, K. S.; Kovacs, S. J.

1975-01-01

This paper derives and summarizes a 'plug-in-and-grind' formalism for calculating the gravitational waves emitted by any system with weak internal gravitational fields. If the internal fields have negligible influence on the system's motions, the formalism reduces to standard 'linearized theory'. Independent of the effects of gravity on the motions, the formalism reduces to the standard 'quadrupole-moment formalism' if the motions are slow and internal stresses are weak. In the general case, the formalism expresses the radiation in terms of a retarded Green's function for slightly curved spacetime and breaks the Green's function integral into five easily understood pieces: direct radiation, produced directly by the motions of the source; whump radiation, produced by the 'gravitational stresses' of the source; transition radiation, produced by a time-changing time delay ('Shapiro effect') in the propagation of the nonradiative 1/r field of the source; focusing radiation, produced when one portion of the source focuses, in a time-dependent way, the nonradiative field of another portion of the source; and tail radiation, produced by 'back-scatter' of the nonradiative field in regions of focusing.

The Research Focus of Nations: Economic vs. Altruistic Motivations.

PubMed

Klavans, Richard; Boyack, Kevin W

2017-01-01

What motivates the research strategies of nations and institutions? We suggest that research primarily serves two masters-altruism and economic growth. Some nations focus more research in altruistic (or non-economic) fields while others focus more research in fields associated with economic growth. What causes this difference? Are there characteristics that would suggest why a nation is more aligned with altruism or economic growth? To answer this question, we have identified nine major fields of research by analyzing the publication activity of 4429 institutions using Scopus data. Two fields of research are clearly altruistic (there is relatively little involvement by industry) and two fields are clearly aligned with economic growth. The altruistic vs. economic nature of nations based on their publication profiles across these fields is correlated with national indicators on wealth, education, capitalism, individualism, power, religion, and language. While previous research has suggested that national research strategy is aligned with national wealth, our analysis shows that national wealth is not highly correlated with the tradeoff between altruistic and economic motives. Instead, the tradeoff is largely captured by a culture of individualism. Accordingly, implications for national research strategies are discussed.

Neuropsychology and cognitive neuroscience in the fMRI era: A recapitulation of localizationist and connectionist views.

PubMed

Sutterer, Matthew J; Tranel, Daniel

2017-11-01

We highlight the past 25 years of cognitive neuroscience and neuropsychology, focusing on the impact to the field of the introduction in 1992 of functional MRI (fMRI). We reviewed the past 25 years of literature in cognitive neuroscience and neuropsychology, focusing on the relation and interplay of fMRI studies and studies utilizing the "lesion method" in human participants with focal brain damage. Our review highlights the state of localist/connectionist research debates in cognitive neuroscience and neuropsychology circa 1992, and details how the introduction of fMRI into the field at that time catalyzed a new wave of efforts to map complex human behavior to specific brain regions. This, in turn, eventually evolved into many studies that focused on networks and connections between brain areas, culminating in recent years with large-scale investigations such as the Human Connectome Project. We argue that throughout the past 25 years, neuropsychology-and more precisely, the "lesion method" in humans-has continued to play a critical role in arbitrating conclusions and theories derived from inferred patterns of local brain activity or wide-spread connectivity from functional imaging approaches. We conclude by highlighting the future for neuropsychology in the context of an increasingly complex methodological armamentarium. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Computation of tightly-focused laser beams in the FDTD method

PubMed Central

Çapoğlu, İlker R.; Taflove, Allen; Backman, Vadim

2013-01-01

We demonstrate how a tightly-focused coherent TEMmn laser beam can be computed in the finite-difference time-domain (FDTD) method. The electromagnetic field around the focus is decomposed into a plane-wave spectrum, and approximated by a finite number of plane waves injected into the FDTD grid using the total-field/scattered-field (TF/SF) method. We provide an error analysis, and guidelines for the discrete approximation. We analyze the scattering of the beam from layered spaces and individual scatterers. The described method should be useful for the simulation of confocal microscopy and optical data storage. An implementation of the method can be found in our free and open source FDTD software (“Angora”). PMID:23388899

Computation of tightly-focused laser beams in the FDTD method.

PubMed

Capoğlu, Ilker R; Taflove, Allen; Backman, Vadim

2013-01-14

We demonstrate how a tightly-focused coherent TEMmn laser beam can be computed in the finite-difference time-domain (FDTD) method. The electromagnetic field around the focus is decomposed into a plane-wave spectrum, and approximated by a finite number of plane waves injected into the FDTD grid using the total-field/scattered-field (TF/SF) method. We provide an error analysis, and guidelines for the discrete approximation. We analyze the scattering of the beam from layered spaces and individual scatterers. The described method should be useful for the simulation of confocal microscopy and optical data storage. An implementation of the method can be found in our free and open source FDTD software ("Angora").

Effects of landscape features on waterbird use of rice fields

USGS Publications Warehouse

King, S.; Elphick, C.S.; Guadagnin, D.; Taft, O.; Amano, T.

2010-01-01

Literature is reviewed to determine the effects of landscape features on waterbird use of fields in regions where rice (Oryza sativa) is grown. Rice-growing landscapes often consist of diverse land uses and land cover, including rice fields, irrigation ditches, other agricultural fields, grasslands, forests and natural wetlands. Numerous studies indicate that local management practices, such as water depth and timing of flooding and drawdown, can strongly influence waterbird use of a given rice field. However, the effects of size and distribution of rice fields and associated habitats at a landscape scale have received less attention. Even fewer studies have focused on local and landscape effects simultaneously. Habitat connectivity, area of rice, distance to natural wetlands, and presence and distance to unsuitable habitat can be important parameters influencing bird use of rice fields. However, responses to a given landscape vary with landscape structure, scale of analysis, among taxa and within taxa among seasons. A lack of multi-scale studies, particularly those extending beyond simple presence and abundance of a given species, and a lack of direct tests comparing the relative importance of landscape features with in-field management activities limits understanding of the importance of landscape in these systems and hampers waterbird conservation and management.

PTSD symptomics: network analyses in the field of psychotraumatology.

PubMed

Armour, Cherie; Fried, Eiko I; Olff, Miranda

2017-01-01

Recent years have seen increasing attention on posttraumatic stress disorder (PTSD) research. While research has largely focused on the dichotomy between patients diagnosed with mental disorders and healthy controls - in other words, investigations at the level of diagnoses - recent work has focused on psychopathology symptoms. Symptomics research in the area of PTSD has been scarce so far, although several studies have focused on investigating the network structures of PTSD symptoms. The present special issue of EJPT adds to the literature by curating additional PTSD network studies, each looking at a different aspect of PTSD. We hope that this special issue encourages researchers to conceptualize and model PTSD data from a network perspective, which arguably has the potential to inform and improve the efficacy of therapeutic interventions.

Force fields and scoring functions for carbohydrate simulation.

PubMed

Xiong, Xiuming; Chen, Zhaoqiang; Cossins, Benjamin P; Xu, Zhijian; Shao, Qiang; Ding, Kai; Zhu, Weiliang; Shi, Jiye

2015-01-12

Carbohydrate dynamics plays a vital role in many biological processes, but we are not currently able to probe this with experimental approaches. The highly flexible nature of carbohydrate structures differs in many aspects from other biomolecules, posing significant challenges for studies employing computational simulation. Over past decades, computational study of carbohydrates has been focused on the development of structure prediction methods, force field optimization, molecular dynamics simulation, and scoring functions for carbohydrate-protein interactions. Advances in carbohydrate force fields and scoring functions can be largely attributed to enhanced computational algorithms, application of quantum mechanics, and the increasing number of experimental structures determined by X-ray and NMR techniques. The conformational analysis of carbohydrates is challengeable and has gone into intensive study in elucidating the anomeric, the exo-anomeric, and the gauche effects. Here, we review the issues associated with carbohydrate force fields and scoring functions, which will have a broad application in the field of carbohydrate-based drug design. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cutting through the smoke: the diversity of microorganisms in deep-sea hydrothermal plumes.

PubMed

Djurhuus, Anni; Mikalsen, Svein-Ole; Giebel, Helge-Ansgar; Rogers, Alex D

2017-04-01

There are still notable gaps regarding the detailed distribution of microorganisms between and within insular habitats such as deep-sea hydrothermal vents. This study investigates the community composition of black smoker vent microorganisms in the Southern Hemisphere, and changes thereof along a spatial and chemical gradient ranging from the vent plume to surrounding waters. We sampled two hydrothermal vent fields, one at the South West Indian Ridge (SWIR), the other at the East Scotia Ridge (ESR). Samples were collected across vent fields at varying vertical distances from the origin of the plumes. The microbial data were sequenced on an Illumina MiSeq platform for the 16SrRNA gene. A substantial amount of vent-specific putative chemosynthetic microorganisms were found, particularly in samples from focused hydrothermal venting. Common vent-specific organisms from both vent fields were the genera Arcobacter , Caminibacter and Sulfurimonas from the Epsilonproteobacteria and the SUP05 group from the Gammaproteobacteria. There were no major differences in microbial composition between SWIR and ESR for focused plume samples. However, within the ESR the diffuse flow and focused samples differed significantly in microbial community composition and relative abundance. For Epsilonproteobacteria, we found evidence of niche-specificity to hydrothermal vent environments. This taxon decreased in abundance by three orders of magnitude from the vent orifice to background water. Epsilonproteobacteria distribution followed a distance-decay relationship as vent-effluents mixed with the surrounding seawater. This study demonstrates strong habitat affinity of vent microorganisms on a metre scale with distinct environmental selection.

Herbicide loading to shallow ground water beneath Nebraska's Management Systems Evaluation Area.

PubMed

Spalding, Roy F; Watts, Darrell G; Snow, Daniel D; Cassada, David A; Exner, Mary E; Schepers, James S

2003-01-01

Better management practices can counter deterioration of ground water quality. From 1991 through 1996 the influence of improved irrigation practices on ground water pesticide contamination was assessed at the Nebraska Management Systems Evaluation Area. Three 13.4-ha corn (Zea mays L.) fields were studied: a conventional furrow-irrigated field, a surge-irrigated field and a center pivot-irrigated field, and a center pivot-irrigated alfalfa (Medicago sativa L.) field. The corn fields received one identical banded application of Bicep (atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4,-diamine] + metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamidel) annually; the alfalfa field was untreated. Ground water samples were collected three times annually from 16 depths of 31 multilevel samplers. Six years of sample data indicated that a greater than 50% reduction in irrigation water on the corn management fields lowered average atrazine concentrations in the upper 1.5 m of the aquifer downgradient of the corn fields from approximately 5.5 to <0.5 microg L(-1). Increases in deethylatrazine (DEA; 2-chloro-4-amino-6-isopropylamino-s-triazine) to atrazine molar ratios indicated that reducing water applications enhanced microbial degradation of atrazine in soil zones. The occurrence of peak herbicide loading in ground water was unpredictable but usually was associated with heavy precipitation within days of herbicide application. Focused recharge of storm runoff that ponded in the surge-irrigated field drainage ditch, in the upgradient road ditch, and at the downgradient end of the conventionally irrigated field was a major mechanism for vertical transport. Sprinkler irrigation technology limited areas for focused recharge and promoted significantly more soil microbial degradation of atrazine than furrow irrigation techniques and, thereby, improved ground water quality.

Optical super-resolution and periodical focusing effects by dielectric microspheres

NASA Astrophysics Data System (ADS)

Darafsheh, Arash

Optical microscopy is one of the oldest and most important imaging techniques; however, its far-field resolution is diffraction-limited. In this dissertation, we proposed and developed a novel method of optical microscopy with super-resolution by using high-index dielectric microspheres immersed in liquid and placed on the surface of the structures under study. We used barium titanate glass microspheres with diameters of D~2-220 mum and refractive indices n˜1.9-2.1 to discern minimal feature sizes ˜lambda/4 (down to ˜lambda/7) of various photonic and plasmonic nanostructures, where lambda is the illumination wavelength. We studied the magnification, field of view, and resolving power, in detail, as a function of sphere sizes. We studied optical coupling, transport, focusing, and polarization properties of linear arrays of dielectric spheres. We showed that in arrays of spheres with refractive index n=3, a special type of rays with transverse magnetic (TM) polarization incident on the spheres under the Brewster's angle form periodically focused modes with radial polarization and 2D period, where D is the diameter of the spheres. We showed that the formation of periodically focused modes in arrays of dielectric spheres gives a physical explanation for beam focusing and extraordinarily small attenuation of light in such chains. We showed that the light propagation in such arrays is strongly polarization-dependent, indicating that such arrays can be used as filters of beams with radial polarization. The effect of forming progressively smaller focused beams was experimentally observed in chains of sapphire spheres in agreement with the theory. We studied optical coupling,transport, focusing, and polarization properties of linear arrays of dielectric spheres. We showed that in arrays of spheres with refractive index n=a3, a special type of rays with transverse magnetic (TM) polarization incident on the spheres under the Brewster's angle form periodically focused modes with radial polarization and 2D period, where D is the diameter of the spheres. We showed that the formation of periodically focused modes in arrays of dielectric spheres gives a physical explanation for beam focusing and extraordinarily small attenuation of light in such chains. We showed that the light propagation in such arrays is strongly polarization-dependent, indicating that such arrays can be used as filters of beams with radial polarization. The effect of forming progressively smaller focused beams was experimentally observed in chains of sapphire spheres in agreement with the theory.

[Deep learning and neuronal networks in ophthalmology : Applications in the field of optical coherence tomography].

PubMed

Treder, M; Eter, N

2018-04-19

Deep learning is increasingly becoming the focus of various imaging methods in medicine. Due to the large number of different imaging modalities, ophthalmology is particularly suitable for this field of application. This article gives a general overview on the topic of deep learning and its current applications in the field of optical coherence tomography. For the benefit of the reader it focuses on the clinical rather than the technical aspects.

Characterization of Pressure Fields of Focused Transducers at TÜBİTAK UME

NASA Astrophysics Data System (ADS)

Karaböce, B.; Şahin, A.; İnce, A. T.; Skarlatos, Y.

Field radiated by HIFU (High Intensity Focused Ultrasound) has been investigated by measuring its pressure field and mapping in 2-D and 3-D. A new ultrasound pressure measurement system has been designed and constructed at TÜBİTAK UME (The Scientific and Technological Research Council of Turkey, the National Metrology Institute). System consists of a water tank, positioning system, measurement devices and a controlling program. The hydrophone was attached to a 3-axis, computer-controlled positioning system for alignment with the ultrasound source. The signal was captured and analyzed by the commercially available LabVIEW 8.1 software. The measurements of the ultrasound field were carried out with a needle hydrophone. For each waveform, p, p+ and p-pressures have been calculated. Wave behaviors produced by the KZK model and from experiments look like similar in general. In p, p+, p- the focal point, zero point after the primary peak (focus) and extremum points in the near field well match.

Mechanisms of thrombolysis acceleration by cavitation

NASA Astrophysics Data System (ADS)

Weiss, Hope; Selvaraj, Prashanth; Ahadi, Golnaz; Voie, Arne; Hoelscher, Thilo; Okita, Kohei; Matsumoto, Yoichiro; Szeri, Andrew

2012-11-01

Recent studies, in vitro and in vivo, have shown that High Intensity Focused Ultrasound (HIFU) accelerates thrombolysis, the dissolution of blood clots, for ischemic stroke. Although the mechanisms are not fully understood, cavitation is thought to play an important role in sonothrombolysis. The damage to a blood clot's fibrin fiber network from cavitation in a HIFU field is studied using two independent approaches for an embedded bubble. One method is extended to the more important scenario of a bubble outside a blood clot that collapses asymmetrically creating a jet towards the clot. There is significantly more damage potential from a bubble undergoing cavitation collapse outside the clot compared to a rapidly expanding bubble embedded within the clot structure. Also, the effects of the physical properties of skull bone when a HIFU wave propagates through it are examined by use of computer simulation. The dynamics of a test bubble placed at the focus is used in understanding of the pressure field. All other things being equal, the analysis suggests that skull thickness can alter the wave at the focus, which in turn can change the nature of cavitation bubble dynamics and the amount of energy available for clot damage. Now at MSOE.

Earth Expeditions: Telling the stories of eight NASA field campaigns by focusing on the human side of science

NASA Astrophysics Data System (ADS)

Bell, S.

2016-12-01

NASA's Earth Right Now communication team kicked off an ambitious multimedia campaign in March 2016 to tell the stories of eight major field campaigns studying regions of critical change from the land, sea and air. Earth Expeditions focused on the human side of science, with live reporting from the field, behind-the-scenes images and videos, and extended storytelling over a six-month period. We reported from Greenland to Namibia, from the eastern United States to the South Pacific. Expedition scientists explored ice sheets, air quality, coral reefs, boreal forests, marine ecosystems and greenhouse gases. All the while the campaign communications team was generating everything from blog posts and social media shareables, to Facebook Live events and a NASA TV series. We also participated in community outreach events and pursued traditional media opportunities. A massive undertaking, we will share lessons learned, best practices for social media and some of our favorite moments when science communication touched our audience's lives.

An assessment of mean-field mixed semiclassical approaches: Equilibrium populations and algorithm stability

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

Bellonzi, Nicole; Jain, Amber; Subotnik, Joseph E.

2016-04-21

We study several recent mean-field semiclassical dynamics methods, focusing on the ability to recover detailed balance for long time (equilibrium) populations. We focus especially on Miller and Cotton’s [J. Phys. Chem. A 117, 7190 (2013)] suggestion to include both zero point electronic energy and windowing on top of Ehrenfest dynamics. We investigate three regimes: harmonic surfaces with weak electronic coupling, harmonic surfaces with strong electronic coupling, and anharmonic surfaces with weak electronic coupling. In most cases, recent additions to Ehrenfest dynamics are a strong improvement upon mean-field theory. However, for methods that include zero point electronic energy, we show thatmore » anharmonic potential energy surfaces often lead to numerical instabilities, as caused by negative populations and forces. We also show that, though the effect of negative forces can appear hidden in harmonic systems, the resulting equilibrium limits do remain dependent on any windowing and zero point energy parameters.« less

The Tölz Temporal Topography Study: mapping the visual field across the life span. Part II: cognitive factors shaping visual field maps.

PubMed

Poggel, Dorothe A; Treutwein, Bernhard; Calmanti, Claudia; Strasburger, Hans

2012-08-01

Part I described the topography of visual performance over the life span. Performance decline was explained only partly by deterioration of the optical apparatus. Part II therefore examines the influence of higher visual and cognitive functions. Visual field maps for 95 healthy observers of static perimetry, double-pulse resolution (DPR), reaction times, and contrast thresholds, were correlated with measures of visual attention (alertness, divided attention, spatial cueing), visual search, and the size of the attention focus. Correlations with the attentional variables were substantial, particularly for variables of temporal processing. DPR thresholds depended on the size of the attention focus. The extraction of cognitive variables from the correlations between topographical variables and participant age substantially reduced those correlations. There is a systematic top-down influence on the aging of visual functions, particularly of temporal variables, that largely explains performance decline and the change of the topography over the life span.

Technical aspects of neurostimulation: Focus on equipment, electric field modeling, and stimulation protocols.

PubMed

Klooster, D C W; de Louw, A J A; Aldenkamp, A P; Besseling, R M H; Mestrom, R M C; Carrette, S; Zinger, S; Bergmans, J W M; Mess, W H; Vonck, K; Carrette, E; Breuer, L E M; Bernas, A; Tijhuis, A G; Boon, P

2016-06-01

Neuromodulation is a field of science, medicine, and bioengineering that encompasses implantable and non-implantable technologies for the purpose of improving quality of life and functioning of humans. Brain neuromodulation involves different neurostimulation techniques: transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), vagus nerve stimulation (VNS), and deep brain stimulation (DBS), which are being used both to study their effects on cognitive brain functions and to treat neuropsychiatric disorders. The mechanisms of action of neurostimulation remain incompletely understood. Insight into the technical basis of neurostimulation might be a first step towards a more profound understanding of these mechanisms, which might lead to improved clinical outcome and therapeutic potential. This review provides an overview of the technical basis of neurostimulation focusing on the equipment, the present understanding of induced electric fields, and the stimulation protocols. The review is written from a technical perspective aimed at supporting the use of neurostimulation in clinical practice. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preliminary demonstration using localized skin temperature elevation as observed with thermal imaging as an indicator of fat-specific absorption during focused-field radiofrequency therapy.

PubMed

Key, Douglas J

2014-07-01

This study incorporates concurrent thermal camera imaging as a means of both safely extending the length of each treatment session within skin surface temperature tolerances and to demonstrate not only the homogeneous nature of skin surface temperature heating but the distribution of that heating pattern as a reflection of localization of subcutaneous fat distribution. Five subjects were selected because of a desire to reduce abdomen and flank fullness. Full treatment field thermal camera imaging was captured at 15 minute intervals, specifically at 15, 30, and 45 minutes into active treatment with the purpose of monitoring skin temperature and avoiding any patterns of skin temperature excess. Peak areas of heating corresponded anatomically to the patients' areas of greatest fat excess ie, visible "pinchable" fat. Preliminary observation of high-resolution thermal camera imaging used concurrently with focused field RF therapy show peak skin heating patterns overlying the areas of greatest fat excess.

Amplification due to two-stream instability of self-electric and magnetic fields of an ion beam propagating in background plasma

NASA Astrophysics Data System (ADS)

Tokluoglu, Erinc K.; Kaganovich, Igor D.; Carlsson, Johan A.; Hara, Kentaro; Startsev, Edward A.

2018-05-01

Propagation of charged particle beams in background plasma as a method of space charge neutralization has been shown to achieve a high degree of charge and current neutralization and therefore enables nearly ballistic propagation and focusing of charged particle beams. Correspondingly, the use of plasmas for propagation of charged particle beams has important applications for transport and focusing of intense particle beams in inertial fusion and high energy density laboratory plasma physics. However, the streaming of beam ions through a background plasma can lead to the development of two-stream instability between the beam ions and the plasma electrons. The beam electric and magnetic fields enhanced by the two-stream instability can lead to defocusing of the ion beam. Using particle-in-cell simulations, we study the scaling of the instability-driven self-electromagnetic fields and consequent defocusing forces with the background plasma density and beam ion mass. We identify plasma parameters where the defocusing forces can be reduced.

Neural network control of focal position during time-lapse microscopy of cells.

PubMed

Wei, Ling; Roberts, Elijah

2018-05-09

Live-cell microscopy is quickly becoming an indispensable technique for studying the dynamics of cellular processes. Maintaining the specimen in focus during image acquisition is crucial for high-throughput applications, especially for long experiments or when a large sample is being continuously scanned. Automated focus control methods are often expensive, imperfect, or ill-adapted to a specific application and are a bottleneck for widespread adoption of high-throughput, live-cell imaging. Here, we demonstrate a neural network approach for automatically maintaining focus during bright-field microscopy. Z-stacks of yeast cells growing in a microfluidic device were collected and used to train a convolutional neural network to classify images according to their z-position. We studied the effect on prediction accuracy of the various hyperparameters of the neural network, including downsampling, batch size, and z-bin resolution. The network was able to predict the z-position of an image with ±1 μm accuracy, outperforming human annotators. Finally, we used our neural network to control microscope focus in real-time during a 24 hour growth experiment. The method robustly maintained the correct focal position compensating for 40 μm of focal drift and was insensitive to changes in the field of view. About ~100 annotated z-stacks were required to train the network making our method quite practical for custom autofocus applications.

An Investigation of Factors Determining the Study Abroad Destination Choice: A Case Study of Taiwan

ERIC Educational Resources Information Center

Lee, Cheng-Fei

2014-01-01

Previous studies on the field of education abroad have mainly focused on the factors influencing the mobility of international students from developing to developed countries and very few have been conducted to investigate the factors influencing the flow of international students to the Asia Pacific region. As a piece of country-specific…

Deaf Studies: A Critique of the Predominant U.S. Theoretical Direction

ERIC Educational Resources Information Center

Myers, Shirley Shultz; Fernandes, Jane K.

2010-01-01

The focus and concerns establishing Deaf Studies in the 1970s have rigidified into a reactive stance toward changing historical conditions and the variety of deaf lives today. This critique analyzes the theoretical foundation of this stance: a tendency to downplay established research in the field of Deaf Studies and linguistics, the employment of…

A Mixed-Methods Study of Alternate-Route Teachers' Effect on Student Learning

ERIC Educational Resources Information Center

Spearman, Cassandra Faye

2017-01-01

Due to teacher shortages at the study site, teaching positions in the state that is the focus of this study are filled by alternate route (AR) teachers, who earned bachelor degrees in the fields that were not related to education and received teacher certification through alternative teacher education programs. Because there is limited information…

Three Cheers for Language: A Closer Examination of a Widely Cited Study of Nonverbal Communication.

ERIC Educational Resources Information Center

Lapakko, David

1997-01-01

Focuses on applications of a widely cited empirical study in the communication field--A. Mehrabian and S. Ferris' 1967 study that inferred that communication is 7% verbal, 38% vocal, and 55% facial. Notes that these applications overlook important limitations which do not warrant formulation of a precise numerical formula. Discusses lessons…

Requisite to Great Undertakings: Impacts of Self-Efficacy Beliefs in College Composition Instructors

ERIC Educational Resources Information Center

Sanchez, Kendall

2017-01-01

This dissertation addresses the problem of teacher self-efficacy theory being largely absent as a concept of study in composition studies, despite the field maintaining a primary focus on issues like teacher development and effective composition pedagogy. This absence of the study of teacher self-efficacy, defined as "a [teacher's] judgment…

A Study of Selected Developing Colleges and Universities. Case Study II: St. Mary's Junior College, Minneapolis, Minnesota.

ERIC Educational Resources Information Center

St. John, Edward P.

As part of a study of selected developing colleges and universities funded in the Advanced Institutional Development Program (AIDP), this report focuses on St. Mary's Junior College (SMJC), a Roman Catholic, two-year college specializing exclusively in health, health-related and human service fields. The report considers SMJC's state of…

Gender and Racial/Ethnic Differences in Salary and Other Characteristics of Postsecondary Faculty: Fall 1998. Statistical Analysis Report.

ERIC Educational Resources Information Center

Bradburn, Ellen M.; Sikora, Anna C.

Using data from the 1999 National Study of Postsecondary Faculty (NSOPF:99), this study examined how gender and race/ethnicity relate to a number of faculty outcomes and characteristics, including: salary, rank, tenure status, education, experience, institution type, teaching field, workload, and research productivity. The study focused on…

Alternation between Work and Education. A Study of Educational Leave of Absence at Enterprise Level.

ERIC Educational Resources Information Center

Organisation for Economic Cooperation and Development, Paris (France). Centre for Educational Research and Innovation.

The study reported here involves six countries (Germany, Italy, Yugoslavia, United Kingdom, United States, and Sweden) and focuses on the ways in which those who are actively employed have access to opportunities to alternate education and training with their employment. The first chapter discusses the study structure and defines the field covered…

Individually addressable cathodes with integrated focusing stack or detectors

DOEpatents

Thomas, Clarence E.; Baylor, Larry R.; Voelkl, Edgar; Simpson, Michael L.; Paulus, Michael J.; Lowndes, Douglas; Whealton, John; Whitson, John C.; Wilgen, John B.

2005-07-12

Systems and method are described for addressable field emission array (AFEA) chips. A plurality of individually addressable cathodes are integrated with an electrostatic focusing stack and/or a plurality of detectors on the addressable field emission array. The systems and methods provide advantages including the avoidance of space-charge blow-up.

Finding Clarity by Fostering Confusion: Reflections on Teaching an Undergraduate Integrated Biological Systems Course

ERIC Educational Resources Information Center

Martin, Kirsten H.

2015-01-01

Undergraduate biology programs in smaller liberal arts colleges are increasingly becoming focused on health science fields. This narrowing of focus potentially decreases opportunities for these students to explore other sub-fields of biology. This perspectives article highlights how one small university in Connecticut decided to institute a…

Protection of neotropical migrants as a major focus of wildlife management

Treesearch

Lawrence J. Niles

1993-01-01

Due to their funding source, wildlife management programs devoted most resources to game species management, and ignored large scale biodiversity initiatives, such as the protection of neotropical migrant land birds. Neotropical migrants are, however, a major focus of the new field of conservation biology, whose proponents consider the field more inclusive than...

Quality and Characteristics of Recent Research in Technology Education

ERIC Educational Resources Information Center

Johnson, Scott D.; Daugherty, Jenny

2008-01-01

The focus of research in technology education has evolved throughout its history as the field changed from industrial arts to technology education (Spencer & Rogers, 2006). With the move to technology education, the field has begun to broaden its focus to better understand the teaching, learning, curriculum, and policy implications of preparing…

Research on Short Duration Pulsed Radiation Sources.

DTIC Science & Technology

correlate soft X-ray spots with the hard radiation in a 1 kJ plasma focus showed that field structures leading to the appearance of soft X-ray spots...are always present in this plasma focus . These field structures represent m = 0 plasma instabilities and do have a direct influence upon the observed neutron emission. (Author)

A vacuum-sealed compact x-ray tube based on focused carbon nanotube field-emission electrons

NASA Astrophysics Data System (ADS)

Jeong, Jin-Woo; Kim, Jae-Woo; Kang, Jun-Tae; Choi, Sungyoul; Ahn, Seungjoon; Song, Yoon-Ho

2013-03-01

We report on a fully vacuum-sealed compact x-ray tube based on focused carbon nanotube (CNT) field-emission electrons for various radiography applications. The specially designed two-step brazing process enabled us to accomplish a good vacuum level for the stable and reliable operation of the x-ray tube without any active vacuum pump. Also, the integrated focusing electrodes in the field-emission electron gun focused electron beams from the CNT emitters onto the anode target effectively, giving a small focal spot of around 0.3 mm with a large current of above 50 mA. The active-current control through the cathode electrode of the x-ray tube led a fast digital modulation of x-ray dose with a low voltage of below 5 V. The fabricated compact x-ray tube showed a stable and reliable operation, indicating good maintenance of a vacuum level of below 5 × 10-6 Torr and the possibility of field-emission x-ray tubes in a stand-alone device without an active pumping system.

Transport Studies of Quantum Magnetism: Physics and Methods

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

Lee, Minhyea

The main goal of this project was to understand novel ground states of spin systems probed by thermal and electrical transport measurements. They are well-suited to characterize the nature of low-energy excitations as unique property of the ground state. More specifically, it was aimed to study the transverse electrical conductivity in the presence of non-collinear and non-coplanar spin ordering and the effects of gauge field as well as novel spin excitations as a coherent heat transport channel in insulating quantum magnets. Most of works done during the grant period focused on these topics. As a natural extension of the project'smore » initial goals, the scope was broadened to include transport studies on the spin systems with strong spin-orbit coupling. One particular focus was an exploration of systems with strong magnetic anisotropy combined with non-trivial spin configuration. Magnetic anisotropy is directly related to implement the non-collinear spin ordering to the existing common geometry of planar devices and thus poses a significant potential. Work in this direction includes the comparison of the topological Hall signal under hydrostatic pressure and chemical doping, as well as the angular dependence dependence of the non-collinear spin ordered phase and their evolution up on temperature and field strength. Another focus was centered around the experimental identification of spin-originated heat carrying excitation in quasi two dimensional honeycomb lattice, where Kitaev type of quantum spin liquid phase is expected to emerge. In fact, when its long range magnetic order is destroyed by the applied field, we discovered anomalously large enhancement of thermal conductivity, for which proximate Kitaev excitations in field-induced spin liquid state are responsible for. This work, combined with further investigations in materials in the similar class may help establish the experimental characterization of new quantum spin liquid and their unique low energy excitation, e.g. Majorana fermions.« less

Applications of Research to Camping.

ERIC Educational Resources Information Center

Henderson, Karla A.

1987-01-01

Considers contributions of basic/theoretical, applied/practical, and marketing research to the field of camping. Outlines research concerns: application of qualitative methods, practical application of marketing research, effective research dissemination, and focus on longitudinal studies using larger samples. Affirms role of research to document…

Microwave scanning beam approach and landing system phased array antenna volume I

DOT National Transportation Integrated Search

1973-02-01

The use of phased arrays for the proposed landing system (MLS) is discussed. Studies relating to ground reflections, near field focusing, and phased-array errors are presented. Two experimental antennas which were fabricated and tested are described....

Microwave scanning beam approach and landing system phased array antenna : volume II

DOT National Transportation Integrated Search

1973-02-01

The use of phased arrays for the proposed landing system (MLS) is discussed. Studies relating to ground reflections, near field focusing, and phased-array errors are presented. Two experimental antennas which were fabricated and tested are described....

Developing and Mentoring Foreign Language Instructors: Best Practices Study Results

DTIC Science & Technology

2013-11-01

directing, and controlling organizational resources” ( Daft , 2008, p. 14) • Instructional supervision is focused on the improvement of...business, management, educational leadership /administration fields Cultural Expertise • Cultural do’s and don’ts, greetings, common phrases, etc. 11

Hydraulic Performance of Shallow Foundations for the Support of Vertical-Wall Bridge Abutments

DOT National Transportation Integrated Search

2017-02-01

This study combined abutment flume experiments with numerical modeling using computational fluid dynamics (CFD) to investigate flow fields and scour at vertical-wall abutments with shallow foundations. The focus was situations dominated by flow contr...

Final report : mobile surveillance and wireless communication systems field operational test. Volume 1, Executive summary

DOT National Transportation Integrated Search

1999-03-01

This study focused on assessing the application of traffic monitoring and management systems which use transportable surveillance and ramp meter trailers, video image processors, and wireless communications. The mobile surveillance and wireless commu...

Problems in Nonlinear Acoustics: Parametric Receiving Arrays, Focused Finite Amplitude Sound, & Noncollinear Tone-Noise Interactions

DTIC Science & Technology

1987-07-01

fields (see also Chapter 4 of Ref. 22). Like our investigation, theirs is based on the Khokhlov-Zabolotskaya-Kuznetsov ( KZK ) equa- tion [23,24...25,26], also based on the KZK e(iualiou, is limited to weakly nonlinear systems. However, the practical case of a focused circular source with gain of...iment. The demonstrated abihty of the KZK equation to accurately model focused sound fields from reahstic sources [i.e., having abrupt edges and

Foil focusing of relativistic electron beams

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

Ekdahl, Jr., Carl August

2017-10-26

When an intense relativistic electron beams (IREB) passes through a grounded metal foil, the transverse electric field due to the beam space charge is locally shorted out, and the beam is focused by the magnetic field of its current. The effect can be treated as focusing by a thin lens with first order aberration. Expressions for the focal length and aberration coefficient of the equivalent thin lens are developed in this note. These are then applied to practical examples representative of IREB research at Los Alamos National Laboratory.

Generation of an incident focused light pulse in FDTD.

PubMed

Capoğlu, Ilker R; Taflove, Allen; Backman, Vadim

2008-11-10

A straightforward procedure is described for accurately creating an incident focused light pulse in the 3-D finite-difference time-domain (FDTD) electromagnetic simulation of the image space of an aplanatic converging lens. In this procedure, the focused light pulse is approximated by a finite sum of plane waves, and each plane wave is introduced into the FDTD simulation grid using the total-field/scattered-field (TF/SF) approach. The accuracy of our results is demonstrated by comparison with exact theoretical formulas.

Generation of an incident focused light pulse in FDTD

PubMed Central

Çapoğlu, İlker R.; Taflove, Allen; Backman, Vadim

2009-01-01

A straightforward procedure is described for accurately creating an incident focused light pulse in the 3-D finite-difference time-domain (FDTD) electromagnetic simulation of the image space of an aplanatic converging lens. In this procedure, the focused light pulse is approximated by a finite sum of plane waves, and each plane wave is introduced into the FDTD simulation grid using the total-field/scattered-field (TF/SF) approach. The accuracy of our results is demonstrated by comparison with exact theoretical formulas. PMID:19582013

Perceptions of community-based field workers on the effect of a longitudinal biomedical research project on their sustainable livelihoods.

PubMed

Moyo, Christabelle S; Francis, Joseph; Bessong, Pascal O

2017-03-17

Researchers involved in biomedical community-based projects rarely seek the perspectives of community fieldworkers, who are the 'foot soldiers' in such projects. Understanding the effect of biomedical research on community-based field workers could identify benefits and shortfalls that may be crucial to the success of community-based studies. The present study explored the perceptions of community-based field workers on the effect of the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development Project" (MAL-ED) South Africa on their tangible and intangible capital which together comprise sustainable livelihoods. The study was conducted in Dzimauli community in Limpopo Province of South Africa between January-February 2016. The sustainable livelihoods framework was used to query community-based field workers' perspectives of both tangible assets such as income and physical assets and intangible assets such as social capital, confidence, and skills. Data were collected through twenty one individual in-depth interviews and one focus group discussion. Data were analysed using the Thematic Content Analysis approach supported by ATLAS.ti, version 7.5.10 software. All the field workers indicated that they benefitted from the MAL-ED South Africa project. The benefits included intangible assets such as acquisition of knowledge and skills, stronger social capital and personal development. Additionally, all indicated that MAL-ED South Africa provided them with the tangible assets of increased income and physical assets. Observations obtained from the focus group discussion and the community-based leaders concurred with the findings from the in-depth interviews. Additionally, some field workers expressed the desire for training in public relations, communication, problem solving and confidence building. The MAL-ED South Africa, biomedical research project, had positive effects on tangible and intangible assets that compose the sustainable livelihoods of community-based fieldworkers. However, the field workers expressed the need to acquire social skills to enable them carry out their duties more efficiently.

Second harmonic generation by self-focusing of intense hollow Gaussian laser beam in collisionless plasma

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

Purohit, Gunjan, E-mail: gunjan75@gmail.com; Rawat, Priyanka; Gauniyal, Rakhi

2016-01-15

The effect of self focused hollow Gaussian laser beam (HGLB) (carrying null intensity in center) on the excitation of electron plasma wave (EPW) and second harmonic generation (SHG) has been investigated in collisionless plasma, where relativistic-ponderomotive and only relativistic nonlinearities are operative. The relativistic change of electron mass and the modification of the background electron density due to ponderomotive nonlinearity lead to self-focusing of HGLB in plasma. Paraxial ray theory has been used to derive coupled equations for the self focusing of HGLB in plasma, generation of EPW, and second harmonic. These coupled equations are solved analytically and numerically tomore » study the laser intensity in the plasma, electric field associated with the excited EPW, and the power of SHG. Second harmonic emission is generated due to nonlinear coupling between incident HGLB and EPW satisfying the proper phase matching conditions. The results show that the effect of including the ponderomotive nonlinearity is significant on the generation of EPW and second harmonic. The electric field associated with EPW and the power of SHG are found to be highly sensitive to the order of the hollow Gaussian beam.« less

Efficient proton acceleration and focusing by an ultraintense laser interacting with a parabolic double concave target with an extended rear

NASA Astrophysics Data System (ADS)

Bake, Muhammad Ali; Xie, Bai-Song; Aimidula, Aimierding; Wang, Hong-Yu

2013-07-01

A new scheme for acceleration and focusing of protons via an improved parabolic double concave target irradiated by an ultraintense laser pulse is proposed. When an intense laser pulse illuminates a concave target, the hot electrons are concentrated on the focal region of the rear cavity and they form a strong space-charge-separation field, which accelerates the protons. For a simple concave target, the proton energy spectrum becomes very broad outside the rear cavity because of transverse divergence of the electromagnetic fields. However, particle-in-cell simulations show that, when the concave target has an extended rear, the hot electrons along the wall surface induce a transverse focusing sheath field, resulting in a clear enhancement of proton focusing, which makes the lower proton energy spread, while, leads to a little reduction of the proton bunch peak energy.

Focused transport of energetic particles along magnetic field lines draped around a coronal mass ejection

NASA Technical Reports Server (NTRS)

Tan, L. C.; Mason, G. M.; Lee, M. A.; Klecker, B.; Ipavich, F. M.

1992-01-01

Evidence is presented for focused transport of energetic particles along magnetic field lines draped around a coronal mass ejection. This evidence was obtained with the University of Maryland/Max-Planck-Institute experiment on the ISEE-3 spacecraft during the decay phase of the June 6, 1979, solar particle event. During the early portion of the decay phase of this event, interplanetary magnetic field lines were apparently draped around a coronal mass ejection, leading to a small focusing length on the western flank where ISEE 3 was located. A period of very slow decrease of particle intensity was observed, along with large sunward anisotropy in the solar wind frame, which is inconsistent with predictions of the standard Fokker-Planck equation models for diffusive transport. It was found possible to fit the observations, assuming that focused transport dominates and that the particle pitch angle scattering is isotropic.

Novel Hamiltonian method for collective dynamics analysis of an intense charged particle beam propagating through a periodic focusing quadrupole lattice a)

NASA Astrophysics Data System (ADS)

Startsev, Edward A.; Davidson, Ronald C.

2011-05-01

Identifying regimes for quiescent propagation of intense beams over long distances has been a major challenge in accelerator research. In particular, the development of systematic theoretical approaches that are able to treat self-consistently the applied oscillating force and the nonlinear self-field force of the beam particles simultaneously has been a major challenge of modern beam physics. In this paper, the recently developed Hamiltonian averaging technique [E. A. Startsev, R. C. Davidson, and M. Dorf, Phys. Rev. ST Accel. Beams 13, 064402 (2010)] which incorporates both the applied periodic focusing force and the self-field force of the beam particles, is generalized to the case of time-dependent beam distributions. The new formulation allows not only a determination of quasi-equilibrium solutions of the non-linear Vlasov-Poison system of equations but also a detailed study of their stability properties. The corrections to the well-known "smooth-focusing" approximation are derived, and the results are applied to a matched beam with thermal equilibrium distribution function. It is shown that the corrections remain small even for moderate values of the vacuum phase advance συ. Nonetheless, because the corrections to the average self-field potential are non-axisymmetric, the stability properties of the different beam quasi-equilibria can change significantly.

X-ray nanofocusing by kinoform lenses: A comparative study using different modeling approaches

NASA Astrophysics Data System (ADS)

Yan, Hanfei

2010-02-01

We conduct a comparative study on various kinoform lenses (KLs) for x-ray nanofocusing by using the geometrical theory, the dynamical diffraction theory, and the beam propagation method. This study shows that the geometrical theory becomes invalid to describe the performance of a KL for nanofocusing. The strong edge diffraction effect from individual lens element, which distorts the desired wave field, leads to a reduction in the effective numerical aperture and imposes a limit on how small a focus a KL can achieve. Because this effect is associated with a finite thickness of a lens, larger lens thickness depicts a stronger distortion. We find that a short KL where all lens elements are folded back to a single plane shows an illumination preference: if the illuminating geometry is in favor of the Bragg diffraction for a focusing order, its performance is enhanced and vice versa. We also find that a short KL usually outperforms its long version where all lens elements do not lie in a single plane because the short one suffers less the wave field distortion due to the edge diffraction. Simulation results suggest that for a long KL, an adaptive lens design is needed to correct the wave field distortion in order to achieve a better performance.

Smoking and Mental Illness: A Bibliometric Analysis of Research Output Over Time

PubMed Central

Wiggers, John H.; Wye, Paula M.; Wolfenden, Luke; Prochaska, Judith J.; Stockings, Emily A.; Williams, Jill M.; Ansell, Kerryn; Fehily, Caitlin; Bowman, Jenny A.

2017-01-01

Introduction: The prevalence of smoking among persons with a mental illness has remained unchanged, being 2–3 times higher than the general population in high-income countries. Assessment of the volume and characteristics of research output over time can assist in identifying research priorities to promote progress within a field. The aim of this study was to undertake such an assessment in the field of smoking and mental illness. Methods: A descriptive repeat cross-sectional study was conducted of peer-reviewed publications in Medline and PsycINFO for the periods 1993–1995, 2003–2005, and 2013–2015. Publications were classified as data- or non-data-based; data-based publications were further categorized by study type, population, setting, and for intervention-focused publications by level of evidence and research translation phase. Results: Included were 547 articles published in 1993–1995 (n = 65), 2003–2005 (n = 153), and 2013–2015 (n = 329). The number and proportion of data-based publications significantly increased over time, although their focus remained predominantly descriptive (≥83%); less than 14% of publications in any period had an intervention focus. The proportion of publications reporting on study populations with multiple diagnostic categories and recruiting from nonmental health settings, significantly increased from 1993–1995 to 2003–2005, however then plateaued by 2013–2015. The level of evidence provided by intervention-focused publications was suggested to increase over time, however there was no evident variation in translation phase. Conclusions: Research has increased over time to characterize smoking among those with a mental illness; however more is needed to inform the development and implementation of effective cessation interventions for this group. Implications: This is the first study to examine the volume and characteristics of research publications in the field of smoking and mental illness over time. The number of publications increased fivefold between 1993–1995 and 2013–2015. Between 1993–1995 and 2003–2005, progression was also indicated by increased: data-based publications, diagnostic diversity of samples, and variation in study settings; however further increases in such measures were not evident in 2013–2015. Notably, it continues to be the case that few intervention studies are undertaken. To achieve meaningful changes in the smoking prevalence of this group, a greater focus on research that assesses the effectiveness and implementation of tailored cessation interventions is required. PMID:27980040

Growth and development of a new subspecialty: pediatric hepatology.

PubMed

Balistreri, William F

2013-08-01

Several major forces converged to catalyze the formal emergence of a body of knowledge and an organized focus on disorders of the liver in early life. Attendant to the development of a focused clinical subspecialty the pace of patient- and laboratory-based research in the field quickened in parallel to decipher the consequences of genetic or metabolic aberrations on immature liver structure and function. The key research observations that catalyzed the emergence and subsequent rapid growth of Pediatric Hepatology include: (1) an understanding of the dynamic events occurring during hepatobiliary development and the importance of these physiologic variables that occur during liver maturation; (2) the recognition of the unique nature of inherited and acquired liver diseases that affect infants and children-such as biliary atresia and Reye's syndrome; and (3) redefinition of the once obscure inherited intrahepatic cholestatic diseases of the liver, which, in turn, provided insight into normal and abnormal hepatobiliary physiology. The clinical advances were highlighted by the development of specific approaches to the diagnosis and management of liver disease in infants and children, including both liver transplantation and nontransplant treatment options. These seminal events led to the expansion of the workforce, creating a critical mass consisting of individuals with focused, specialized skills and techniques. In-depth expertise allowed more accurate diagnosis and highly effective treatment strategies for advanced hepatobiliary disease in children. The demand for pediatric clinicians with experience in advanced hepatology allowed sub-sub-specialization to flourish. Continued maturation of the field led to definition of hepatology-focused curricular elements and educational content for Pediatric Gastroenterology training programs, and subsequently the development of program requirements for those who wished to acquire additional training in Pediatric Hepatology. A significant rite of passage was marked by the election of pediatric hepatologists to leadership positions in the American Association for the Study of Liver Diseases (AASLD). Further validation of the field occurred with approval of the petition for establishing a Certificate of Added Qualification in Transplant Hepatology by the American Board of Pediatrics. Here I relate my perspective on the history of the advances in our field and the contributions of many of the clinicians and scientists whose efforts led to the development of focused clinical, research, and training programs that improved the care of children with diseases of the liver. Copyright © 2013 by the American Association for the Study of Liver Diseases.

Effects of land management strategies on the dispersal pattern of a beneficial arthropod.

PubMed

Marchi, Chiara; Andersen, Liselotte Wesley; Loeschcke, Volker

2013-01-01

Several arthropods are known to be highly beneficial to agricultural production. Consequently it is of great relevance to study the importance of land management and land composition for the conservation of beneficial aphid-predator arthropod species in agricultural areas. Therefore our study focusing on the beneficial arthropod Bembidion lampros had two main purposes: I) identifying the physical barriers to the species' dispersal in the agricultural landscape, and II) assessing the effect of different land management strategies (i.e. use of pesticides and intensiveness) on the dispersal patterns. The study was conducted using genetic analysis (microsatellite markers) applied to samples from two agricultural areas (in Denmark) with different agricultural intensity. Land management effects on dispersal patterns were investigated with particular focus on: physical barriers, use of pesticide and intensity of cultivation. The results showed that Bembidion lampros disperse preferably through hedges rather than fields, which act as physical barriers to gene flow. Moreover the results support the hypothesis that organic fields act as reservoirs for the re-colonization of conventional fields, but only when cultivation intensity is low. These results show the importance of non-cultivated areas and of low intensity organic managed areas within the agricultural landscape as corridors for dispersal (also for a species typically found within fields). Hence, the hypothesis that pesticide use cannot be used as the sole predictor of agriculture's effect on wild species is supported as land structure and agricultural intensity can be just as important.

The Role of Convective Shell Thickness on Dynamo Scaling Laws for Magnetic Field Morphology: Implications for the Ice Giants and Future Earth

NASA Astrophysics Data System (ADS)

Stanley, S.; Tian, B. Y.

2016-12-01

Previous dynamo scaling law studies (Christensen and Aubert, 2006) have demonstrated that the morphology of a planet's magnetic field is determined by the local Rossby number (Rol): a non-dimensional diagnostic variable that quantifies the ratio of inertial forces to Coriolis forces on the average length scale of the flow. Dynamos with Rol < 0.1 produce dipolar dominated magnetic fields whereas dynamos with Rol > 0.1 produce multipolar magnetic fields. Scaling studies have also determined the dependence of the local Rossby number on non-dimensional parameters governing the system - specifically the Ekman, Prandtl, magnetic Prandtl and flux-based Rayleigh numbers (Olson and Christensen, 2006). However, those studies focused on the specific convective shell thickness of the Earth's core and hence could not determine the influence of convective shell thickness on the local Rossby number. Aubert et al. (2009) investigated the role of convective shell thickness on dynamo scaling laws in order to investigate the palaeo-evolution of the geodynamo. Due to the focus of that study, they varied the ratio of the inner to outer core radii (rio) from 0 to 0.35 and found Rol scales with (1+rio). Here we consider a larger range of convective shell thicknesses and find an exponential dependence of rio on the local Rossby number. Our results are consistent with Aubert et al. (2009) for their small rio values. With this new scaling dependence on convective shell thickness, we find that Uranus and Neptune reside deeply in the multipolar regime, whereas without the dependence on rio, they resided near Rol =0.1; i.e. on the boundary between dipolar and multipolar fields and close to where Earth resides in the parameter space. We also find that Earth will reside more deeply in the multipolar regime, and hence not produce a stable dipolar field once the inner core has grown such that rio = 0.4.

Growth in conventional fields in high-cost areas: a case study

USGS Publications Warehouse

Attanasi, E.D.

2000-01-01

Exploration managers commonly base future drilling decisions on past experience in an area. To do this well, they should consider both discovered and undiscovered resources to characterize total future potential. Discovery-size estimates should be adjusted to account for future field growth; otherwise, the relative efficiency of recent exploration will be undervalued. This study models and projects field growth for pre-1997 discoveries in the U.S. Federal Gulf of Mexico (GOM) Outer Continental Shelf (OCS). Projected additions to reserves for these fields from field growth through 2020 are 5.2 billion bbl of oil and 46 Tcfg. Projections include growth associated with sizable new oil discoveries in deepwater areas and initial reserve additions from new subsalt plays discovered through 1996. This article focuses on the U.S. GOM because it has produced longer than other worldwide offshore areas. Its field-growth profile may be prototypical of other offshore provinces such as the North Sea, Scotian Shelf and deepwater Angola, as well as high-cost onshore areas.

Supporting the Use of GPM-GV Field Campaign Data Beyond Project Scientists

NASA Astrophysics Data System (ADS)

Weigel, A. M.; Smith, D. K.; Sinclair, L.; Bugbee, K.

2017-12-01

The Global Precipitation Measurement (GPM) Mission Ground Validation (GV) consisted of a collection of field campaigns at various locations focusing on particular aspects of precipitation. Data collected during the GPM-GV are necessary for better understanding the instruments and algorithms used to monitor water resources, study the global hydrologic cycle, understand climate variability, and improve weather prediction. The GPM-GV field campaign data have been archived at the NASA Global Hydrology Resource Center (GHRC) Distributed Achive Archive Center (DAAC). These data consist of a heterogeneous collection of observations that require careful handling, full descriptive user guides, and helpful instructions for data use. These actions are part of the data archival process. In addition, the GHRC focuses on expanding the use of GPM-GV data beyond the validation and instrument researchers that participated in the field campaigns. To accomplish this, GHRC ties together the similarities and differences between the various field campaigns with the goal of improving user documents to be more easily read by those outside the field of research. In this poster, the authors will describe the GPM-GV datasets, discuss data use among the broader community, outline the types of problems/issues with these datasets, demonstrate what tools support data visualization and use, and highlight the outreach materials developed to educate both younger and general audiences about the data.

The skeleton in the closet: should historians of science care about the history of mathematics?

PubMed

Alexander, Amir

2011-09-01

Up until the 1950s, the history of mathematics was an integral part of the history of science. To George Sarton and his contemporaries, mathematics was the rational skeleton that organized science and held it together, and its history was a fundamental component of the broader history of science. But when historians began focusing on the cultural roots of science rather than its rational structure, the study of mathematics was marginalized and ultimately excluded from the history of science. The alienation between the two fields is detrimental to both, and in recent years there has been a sustained effort to reestablish meaningful communication between the two. This time, however, mathematics is seen not as the static skeleton of science but, instead, as a dynamic and historically evolving field in its own right-just like science itself. The new approach allows for a culturally sensitive study of mathematics, as well as a new and fruitful relationship between the history of science and the history of mathematics. The essays in this Focus section offer a sampling of the new approaches, opening the way to a rapprochement between fields that have gone their separate ways but should by rights be closely interconnected.

Development of a real-time wave field reconstruction TEM system (II): correction of coma aberration and 3-fold astigmatism, and real-time correction of 2-fold astigmatism.

PubMed

Tamura, Takahiro; Kimura, Yoshihide; Takai, Yoshizo

2018-02-01

In this study, a function for the correction of coma aberration, 3-fold astigmatism and real-time correction of 2-fold astigmatism was newly incorporated into a recently developed real-time wave field reconstruction TEM system. The aberration correction function was developed by modifying the image-processing software previously designed for auto focus tracking, as described in the first article of this series. Using the newly developed system, the coma aberration and 3-fold astigmatism were corrected using the aberration coefficients obtained experimentally before the processing was carried out. In this study, these aberration coefficients were estimated from an apparent 2-fold astigmatism induced under tilted-illumination conditions. In contrast, 2-fold astigmatism could be measured and corrected in real time from the reconstructed wave field. Here, the measurement precision for 2-fold astigmatism was found to be ±0.4 nm and ±2°. All of these aberration corrections, as well as auto focus tracking, were performed at a video frame rate of 1/30 s. Thus, the proposed novel system is promising for quantitative and reliable in situ observations, particularly in environmental TEM applications.

DNA repair: a changing geography? (1964-2008).

PubMed

Maisonobe, Marion; Giglia-Mari, Giuseppina; Eckert, Denis

2013-07-01

This article aims to explain the current state of DNA Repair studies' global geography by focusing on the genesis of the community. Bibliometric data is used to localize scientific activities related to DNA Repair at the city level. The keyword "DNA Repair" was introduced first by American scientists. It started to spread after 1964 that is to say, after P. Howard-Flanders (Yale University), P. Hanawalt (Stanford University) and R. Setlow (Oak Ridge Laboratories) found evidence for Excision Repair mechanisms. It was the first stage in the emergence of an autonomous scientific community. In this article, we will try to assess to what extent the geo-history of this scientific field is determinant in understanding its current geography. In order to do so, we will localize the places where the first "DNA Repair" publications were signed fifty years ago and the following spatial diffusion process, which led to the current geography of the field. Then, we will focus on the evolution of the research activity of "early entrants" in relation to the activity of "latecomers". This article is an opportunity to share with DNA Repair scientists some research results of a dynamic field in Science studies: spatial scientometrics. Copyright © 2013 Elsevier B.V. All rights reserved.

Enhancement of Pool Boiling Heat Transfer and Control of Bubble Motion in Microgravity Using Electric Fields - BCOEL

NASA Technical Reports Server (NTRS)

Herman, Cila; Iacona, Estelle; Acquaviva, Tom; Coho, Bill; Grant, Nechelle; Nahra, Henry; Sankaran, Subramanian; Taylor, Al; Julian, Ed; Robinson, Dale;

Transcranial measurements of the acoustic field produced by a low frequency focused ultrasound system

NASA Astrophysics Data System (ADS)

Voie, Arne; Fisher, David; Ahadi, Golnaz; Hölscher, Thilo

2012-11-01

The purpose of this study was to ascertain the effects of the skull on the location, shape and power of the acoustic field produced by a 150 mm radius hemispherical array operating at 220 kHz. We wanted to determine whether phase aberrations were significant at this frequency, the amount of attenuation, and whether CT data could be predictive of the trans-skull field. The effects of five calvaria were evaluated. Acoustic field data and CT scans for each skull specimen were imported into MATLAB® for measurements and visualization in two and three dimensions. We examined the effects of skull density, porosity, thickness, and sonication incident angles, and estimated the relative contributions of longitudinal and shear transmission to the total transmitted power. Power transmission through the skulls varied between 4% and 23% (mean: 12%). The range of focal position shifts was from 0.50 mm to 4.32 mm (mean: 1.95 mm). The 3 dB dimensions of the focused ultrasound (FUS) intensity focal volume increased on average by 39% (low: 4%, high: 122%). The 6 dB pressure focal volume increased by an average of 130 ± 75%. In general, the main effects of the skulls were power reduction, field dispersion and slight shift of focal peak location.

Enhancement of Pool Boiling Heat Transfer and Control of Bubble Motion in Microgravity Using Electric Fields (BCOEL)

NASA Technical Reports Server (NTRS)

Herman, Cila; Iacona, Estelle; Acquaviva, Tom; Coho, Bill; Grant, Nechelle; Nahra, Henry; Taylor, Al; Julian, Ed; Robinson, Dale; VanZandt, Dave

2001-01-01

The BCOEL project focuses on improving pool boiling heat transfer and bubble control in microgravity by exposing the fluid to electric fields. The electric fields induce a body force that can replace gravity in the low gravity environment, and enhance bubble removal from the heated surface. A better understanding of microgravity effects on boiling with and without electric fields is critical to the proper design of the phase-change-heat-removal equipment for use in spacebased applications. The microgravity experiments will focus on the visualization of bubble formation and shape during boiling. Heat fluxes on the boiling surface will be measured, and, together with the measured driving temperature differences, used to plot boiling curves for different electric field magnitudes. Bubble formation and boiling processes were found to be extremely sensitive to g-jitter. The duration of the experimental run is critical in order to achieve steady state in microgravity experiments. The International Space Station provides conditions suitable for such experiments. The experimental apparatus to be used in the study is described in the paper. The apparatus will be tested in the KC-135 first, and microgravity experiments will be conducted on board of the International Space Station using the Microgravity Science Glovebox as the experimental platform.

A Grid Sourcing and Adaptation Study Using Unstructured Grids for Supersonic Boom Prediction

NASA Technical Reports Server (NTRS)

Carter, Melissa B.; Deere, Karen A.

2008-01-01

NASA created the Supersonics Project as part of the NASA Fundamental Aeronautics Program to advance technology that will make a supersonic flight over land viable. Computational flow solvers have lacked the ability to accurately predict sonic boom from the near to far field. The focus of this investigation was to establish gridding and adaptation techniques to predict near-to-mid-field (<10 body lengths below the aircraft) boom signatures at supersonic speeds using the USM3D unstructured grid flow solver. The study began by examining sources along the body the aircraft, far field sourcing and far field boundaries. The study then examined several techniques for grid adaptation. During the course of the study, volume sourcing was introduced as a new way to source grids using the grid generation code VGRID. Two different methods of using the volume sources were examined. The first method, based on manual insertion of the numerous volume sources, made great improvements in the prediction capability of USM3D for boom signatures. The second method (SSGRID), which uses an a priori adaptation approach to stretch and shear the original unstructured grid to align the grid and pressure waves, showed similar results with a more automated approach. Due to SSGRID s results and ease of use, the rest of the study focused on developing a best practice using SSGRID. The best practice created by this study for boom predictions using the CFD code USM3D involved: 1) creating a small cylindrical outer boundary either 1 or 2 body lengths in diameter (depending on how far below the aircraft the boom prediction is required), 2) using a single volume source under the aircraft, and 3) using SSGRID to stretch and shear the grid to the desired length.

Evaluating Teachers' Professional Development Initiatives: Towards an Extended Evaluative Framework

ERIC Educational Resources Information Center

Merchie, Emmelien; Tuytens, Melissa; Devos, Geert; Vanderlinde, Ruben

2018-01-01

Evaluating teachers' professional development initiatives (PDI) is one of the main challenges for the teacher professionalisation field. Although different studies have focused on the effectiveness of PDI, the obtained effects and evaluative methods have been found to be widely divergent. By means of a narrative review, this study provides an…

Comparative Historical Approaches in Religious Education Research--Methodological Perspectives

ERIC Educational Resources Information Center

Schröder, Bernd

2016-01-01

This article summarises the state of comparative historical research in the field of religious education. After describing a range of purposes to be fulfilled by comparative studies, it categorises a number of studies written in either English, French or German according to their methodological approach and subject focus. As a result, a…

Insects. Hawaii Nature Study Project.

ERIC Educational Resources Information Center

Hawaii Univ., Honolulu. Curriculum Research and Development Group.

This teaching guide is one of a series developed by the Curriculum Research and Development Group at the University of Hawaii. The program is laboratory and field oriented for elementary students. The focus of study for the project is the plant and animal life and the physical components of the Hawaiian environment, and their ecological…

Instructional Strategies to Support Creativity and Innovation in Education

ERIC Educational Resources Information Center

Seechaliao, Thapanee

2017-01-01

The purpose of the study focused on the instructional strategies that support creation of creative and innovative education. The sample for this study consisted of 11 experts in the field of instructional strategies that support innovation of education. Among them, five were specialists in design and development of teaching and learning, three…

Dynamic Systems for Individual Tracking via Heterogeneous Information Integration and Crowd Source Distributed Simulation

DTIC Science & Technology

2015-12-04

51   6.6   Power Consumption: Communications ...simulations executing on mobile computing platforms, an area not widely studied to date in the distributed simulation research community . A...simulation community . These initial studies focused on two conservative synchronization algorithms widely used in the distributed simulation field

Reboot: Revisiting Factors Influencing Female Selection of the CIS Major

ERIC Educational Resources Information Center

Hodges, Darin; Corley, Ken

2017-01-01

A concern among many universities, this study reflects and continues research on the changing attitude and intent of selecting a Computer Information Systems major. Focusing on the gender gap for selection of major for women in this field, studies indicate instrumental beliefs and subjective norms can influence behavior and indicate how selection…

Explaining the Effectiveness of the Contrast Culture Method for Managing Interpersonal Interactions across Cultures

ERIC Educational Resources Information Center

Hiratsuka, Hiroyoshi; Suzuki, Hanako; Pusina, Alexis

2016-01-01

One of the current challenges in the field of intercultural education comes from the limited availability of training efficacy studies. The present study focused on explaining the effectiveness of the Contrast Culture Method (CCM) as an intercultural education method for managing interpersonal interactions across cultures between graduate…

Economics of growth regulator treatment of alfalfa seed for interseeding into silage corn

USDA-ARS?s Scientific Manuscript database

Previous studies have focused on interseeding of alfalfa into corn for use as a temporary cover crop rather than as a means of jump-starting alfalfa production after corn. In ongoing field studies, we are evaluating whether plant growth regulators (PGR) may be used to aid the establishment of inters...

Investigation of EFL Teachers' Career and Motivation at Universities in Japan

ERIC Educational Resources Information Center

Tsutsumi, Rie

2013-01-01

Motivation is one of the most popular topics on language teaching and learning. Many studies on language learning focus on students' motivation; however, teachers' motivation is easily overlooked in the area of the applied linguistics field. In this paper, the researcher presents a study to investigate how satisfied English teachers at private…

Educator's Barriers to Using Technology

ERIC Educational Resources Information Center

Brown, April S.

2012-01-01

The study is an action research project focused on learning more about the barriers to using technology at one site in Southern California. Learning about the barriers for one school may assist this researcher in learning how to improve the changes of teachers and staff using technology in the field of education. The methodology of this study was…

Recruiting Females into Male Dominated Programs: Effective Strategies and Approaches

ERIC Educational Resources Information Center

Tsui, Lisa

2009-01-01

This study examines the recruitment of women into a heavily male dominated field of study, in this case mechanical engineering. Qualitative data, in the form of interviews and focus groups, were gathered from six undergraduate mechanical engineering programs that enroll and graduate a relatively high proportion of women. Results revealed that (1)…

Getting Them Speaking: Classroom Social Factors and Foreign Language Anxiety

ERIC Educational Resources Information Center

Effiong, Okon

2016-01-01

This study, which focuses on foreign language anxiety (FLA) experienced by Japanese learners of English in four universities, explores causative agents by looking into the classroom. The research questions aim to explore how FLA is influenced by classroom social factors. The study adopted qualitative data collection procedures, and the field work…

Pedagogical Differences during a Science and Language Intervention for English Language Learners

ERIC Educational Resources Information Center

Garza, Tiberio; Huerta, Margarita; Lara-Alecio, Rafael; Irby, Beverly J.; Tong, Fuhui

2018-01-01

The purpose of this study was to compare and describe 8 fifth-grade classrooms by their teachers pedagogy during a quasiexperimental, longitudinal, and field-based project focused on increasing English language learners' (ELLs') achievement in science and language. The larger study found statistically significant and positive intervention effects…

Parts of Plants. Hawaii Nature Study Project.

ERIC Educational Resources Information Center

Hawaii Univ., Honolulu. Curriculum Research and Development Group.

This teaching guide is one of a series developed by the Curriculum Research and Development Group at the University of Hawaii. The program is laboratory and field oriented for elementary students. The focus of study for the project is the plant and animal life and the physical components of the Hawaiian environment, and their ecological…

What Motivates Introductory Geology Students to Study for an Exam?

ERIC Educational Resources Information Center

Lukes, Laura A.; McConnell, David A.

2014-01-01

There is a need to understand why some students succeed and persist in STEM fields and others do not. While numerous studies have focused on the positive results of using empirically validated teaching methods in introductory science, technology, engineering, and math (STEM) courses, little data has been collected about the student experience in…

Sustainable Imaginaries: A Case Study of a Large Suburban Canadian University

ERIC Educational Resources Information Center

Vaughter, Philip; Alsop, Steve

2017-01-01

Purpose: This paper aims to explore the concept of sustainability imaginaries--unifying core assumptions on what sustainability entails held by stakeholders--set within a large suburban Canadian university. The study aims to expand the field of research into imaginaries by focusing on imaginaries within an institution as opposed to a societal or…

Inclusion Reconceptualized: Pre-Service Teacher Education and Disability Studies in Education

ERIC Educational Resources Information Center

Gilham, Christopher M.; Tompkins, Joanne

2016-01-01

In this article, two teacher educators describe and explain how they are reconceptualizing a pre-service teacher education course on inclusion using disability studies in education (DSE) scholarship. The DSE approach better connects the oft-separated field of diversity and inclusion, and builds on the program's overall focus on equity education.…

Ethnographies of Higher Education: Introduction to the Special Issue

ERIC Educational Resources Information Center

Pabian, Petr

2014-01-01

While acknowledging that ethnography has been a rarely adopted approach in the field of higher education research, I will try to demonstrate the contributions that ethnographies have made to higher education studies. I will introduce readers to several of the most important and interesting ethnographic studies of university settings, focusing on…

Researching Language Teacher Cognition and Practice: International Case Studies

ERIC Educational Resources Information Center

Barnard, Roger, Ed.; Burns, Anne, Ed.

2012-01-01

This book presents a novel approach to discussing how to research language teacher cognition and practice. An introductory chapter by the editors and an overview of the research field by Simon Borg precede eight case studies written by new researchers, each of which focuses on one approach to collecting data. These approaches range from…

Intercultural Education in the European Context: Key Remarks from a Comparative Study

ERIC Educational Resources Information Center

Catarci, Marco

2014-01-01

The article focuses on some findings of a comparative study carried out by a network of scholars and researchers who are active in the field of intercultural education in the European context in the main "old immigration countries" (United Kingdom, France and Germany), "new immigration countries" (Italy, Spain and Greece) and…

Entrepreneurship for Bioscience Researchers: A Case Study of an Entrepreneurship Programme

ERIC Educational Resources Information Center

Heinonen, Jarna; Poikkijoki, Sari-Anne; Vento-Vierikko, Irma

2007-01-01

Entrepreneurship is reaching new areas in which the concept of business is more or less unfamiliar and remote. This study focuses on a specific entrepreneurship education programme in the fields of chemistry, physics, information technology and bioinformatics, life sciences and medicine development. The aim is to gain a deeper understanding of the…

Towards the Development of a Biliterate Pedagogy: A Case Study of Emerging Biliterate Writing

ERIC Educational Resources Information Center

Butvilofsky, Sandra Adriana

2010-01-01

More than 60% of children labeled English language learners in U.S. schools today are simultaneous bilinguals, and little is understood about their bilingual and biliterate potential, because theories of sequential bilingualism dominate the field. Most studies exploring bilingual children's writing development have focused almost exclusively on…

Introduction to a Comparative Study of Educational Administration.

ERIC Educational Resources Information Center

Lynch, Patrick D.

Comparative educational administration is not yet a recognized field, although a number of works concerning cross-cultural educational literature are directly applicable to such studies. Four themes are apparent in relevant works. Beginning in the 19th century, the earliest works focused on European schools in the hopes America could learn from…

Coping Power Dissemination Study: Intervention and Special Education Effects on Academic Outcomes

ERIC Educational Resources Information Center

Lochman, John E.; Boxmeyer, Caroline L.; Powell, Nicole P.; Qu, Lixin; Wells, Karen; Windle, Michael

2012-01-01

This study examines whether a school-based preventive intervention for children with aggressive behavior affects children's academic outcomes when it is implemented by school counselors in a dissemination field trial. The Coping Power program targets empirical risk factors for aggressive behavior and focuses primarily on teaching social and…

Reef and Shore. Hawaii Nature Study Project.

ERIC Educational Resources Information Center

Hawaii Univ., Honolulu. Curriculum Research and Development Group.

This teaching guide is one of a series developed by the Curriculum Research and Development Group at the University of Hawaii. The program is laboratory and field oriented for elementary students. The focus of study for the project is the plant and animal life and the physical components of the Hawaiian environment, and their ecological…

Education for Action: Undergraduate and Graduate Programs That Focus on Social Change. Fourth Edition.

ERIC Educational Resources Information Center

Powell, Joan, Ed.

This book provides graduates and undergraduates with detailed information about progressive programs for current and future activities in a variety of fields. Each entry contains a description of the program with faculty and program contact information. Listings include programs in agriculture, anthropology, area studies, development studies,…

Bandwidth Limitations in Characterization of High Intensity Focused Ultrasound Fields in the Presence of Shocks

NASA Astrophysics Data System (ADS)

Khokhlova, V. A.; Bessonova, O. V.; Soneson, J. E.; Canney, M. S.; Bailey, M. R.; Crum, L. A.

2010-03-01

Nonlinear propagation effects result in the formation of weak shocks in high intensity focused ultrasound (HIFU) fields. When shocks are present, the wave spectrum consists of hundreds of harmonics. In practice, shock waves are modeled using a finite number of harmonics and measured with hydrophones that have limited bandwidths. The goal of this work was to determine how many harmonics are necessary to model or measure peak pressures, intensity, and heat deposition rates of the HIFU fields. Numerical solutions of the Khokhlov-Zabolotskaya-Kuznetzov-type (KZK) nonlinear parabolic equation were obtained using two independent algorithms, compared, and analyzed for nonlinear propagation in water, in gel phantom, and in tissue. Measurements were performed in the focus of the HIFU field in the same media using fiber optic probe hydrophones of various bandwidths. Experimental data were compared to the simulation results.

Micromachined mold-type double-gated metal field emitters

NASA Astrophysics Data System (ADS)

Lee, Yongjae; Kang, Seokho; Chun, Kukjin

1997-12-01

Electron field emitters with double gates were fabricated using micromachining technology and the effect of the electric potential of the focusing gate (or second gate) was experimentally evaluated. The molybdenum field emission tip was made by filling a cusplike mold formed when a conformal film was deposited on the hole-trench that had been patterned on stacked metals and dielectric layers. The hole-trench was patterned by electron beam lithography and reactive ion etching. Each field emitter has a 0960-1317/7/4/009/img1 diameter extraction gate (or first gate) and a 0960-1317/7/4/009/img2 diameter focusing gate (or second gate). To make a path for the emitted electrons, silicon bulk was etched anisotropically in KOH and EDP (ethylene-diamine pyrocatechol) solution successively. The I - V characteristics and anode current change due to the focusing gate potential were measured.

Radio frequency focused interdigital linear accelerator

DOEpatents

Swenson, Donald A.; Starling, W. Joel

2006-08-29

An interdigital (Wideroe) linear accelerator employing drift tubes, and associated support stems that couple to both the longitudinal and support stem electromagnetic fields of the linac, creating rf quadrupole fields along the axis of the linac to provide transverse focusing for the particle beam. Each drift tube comprises two separate electrodes operating at different electrical potentials as determined by cavity rf fields. Each electrode supports two fingers, pointing towards the opposite end of the drift tube, forming a four-finger geometry that produces an rf quadrupole field distribution along its axis. The fundamental periodicity of the structure is equal to one half of the particle wavelength .beta..lamda., where .beta. is the particle velocity in units of the velocity of light and .lamda. is the free space wavelength of the rf. Particles are accelerated in the gaps between drift tubes. The particle beam is focused in regions inside the drift tubes.

Wide Field Collimator 2 (WFC2) for GOES Imager and Sounder

NASA Technical Reports Server (NTRS)

Etemad, Shahriar; Bremer, James C.; Zukowski, Barbara J.; Pasquale, Bert A.; zukowski, Tmitri J.; Prince, Robert E.; O'Neill, Patrick A.; Ross, Robert W.

2004-01-01

Two of the GOES instruments, the Imager and the Sounder, perform scans of the Earth to provide a full disc picture of the Earth. To verify the entire scan process, an image of a target that covers an 18 deg. circular field-of-view is collimated and projected into the field of regard of each instrument. The Wide Field Collimator 2 (WFC2) has many advantages over its predecessor, WFC1, including lower thermal dissipation higher fir field MTF, smaller package, and a more intuitive (faster) focusing process. The illumination source is an LED array that emits in a narrow spectral band centered at 689 nm, within the visible spectral bands of the Imager and Sounder. The illumination level can be continuously adjusted electronically. Lower thermal dissipation eliminates the need for forced convection cooling and minimizes time to reach thermal stability. The lens system has been optimized for the illumination source spectral output and athernalized to remain in focus during bulk temperature changes within the laboratory environment. The MTF of the lens is higher than that of the WFC1 at the edge of FOV. The target is focused in three orthogonal motions, controlled by an ergonomic system that saves substantial time and produces a sharper focus. Key words: Collimator, GOES, Imager, Sounder, Projector

Stand-off explosive detection utilizing low power stimulated emission nuclear quadrupole resonance detection and subwavelength focusing wideband super lens

NASA Astrophysics Data System (ADS)

Apostolos, John; Mouyos, William; Feng, Judy; Chase, Walter

2015-05-01

The need for advanced techniques to detect improvised explosive devices (IED) at stand-off distances greater than ten (10) meters has driven AMI Research and Development (AMI) to develop a solution to detect and identify the threat utilizing a forward looking Synthetic Aperture Radar (SAR) combined with our CW radar technology Nuclear Quadrupole Resonance (NQR) detection system. The novel features include a near-field sub-wavelength focusing antenna, a wide band 300 KHz to 300 MHz rapidly scanning CW radar facilitated by a high Q antenna/tuner, and an advanced processor utilizing Rabi transitions where the nucleus oscillates between states under the time dependent incident electromagnetic field and alternately absorbs energy from the incident field while emitting coherent energy via stimulated emission. AMI's Sub-wavelength Focusing Wide Band Super Lens uses a Near-Field SAR, making detection possible at distances greater than ten (10) meters. This super lens is capable of operating on the near-field and focusing electromagnetic waves to resolutions beyond the diffraction limit. When applied to the case of a vehicle approaching an explosive hazard the methodologies of synthetic aperture radar is fused with the array based super resolution and the NQR data processing detecting the explosive hazard.

Three-dimensional characterization of tightly focused fields for various polarization incident beams

NASA Astrophysics Data System (ADS)

Cai, Yanan; Liang, Yansheng; Lei, Ming; Yan, Shaohui; Wang, Zhaojun; Yu, Xianghua; Li, Manman; Dan, Dan; Qian, Jia; Yao, Baoli

2017-06-01

Tightly focused vectorial optical beams have found extensive applications in variety of technical fields like single-molecule detection, optical tweezers, and super-resolution optical microscopy. Such applications require an accurate measurement and manipulation of focal optical fields. We have developed a compact instrument (with dimensions of 35 × 35 × 30 cm3) to rapidly measure the intensity distribution in three dimensions of the focused fields of vectorial beams and any other incident beams. This instrument employs a fluorescent nanoparticle as a probe to scan the focal region to obtain a high spatial resolution of intensity distribution. It integrates a liquid-crystal spatial light modulator to allow for tailoring the point spread function of the optical system, making it a useful tool for multi-purpose and flexible research. The robust applicability of the instrument is verified by measuring the 3D intensity distributions of focal fields of various polarization and wavefront modulated incident beams focused by a high NA (=1.25) objective lens. The minimal data acquisition time achievable in the experiment is about 8 s for a scanning region of 3.2 × 3.2 μm2 (512 × 512 pixels). The measured results are in good agreement with those predicted by the vectorial diffraction theory.

Modeling and Analysis of Geoelectric Fields: Extended Solar Shield

NASA Astrophysics Data System (ADS)

Ngwira, C. M.; Pulkkinen, A. A.

2016-12-01

In the NASA Applied Sciences Program Solar Shield project, an unprecedented first-principles-based system to forecast geomagnetically induced current (GIC) in high-voltage power transmission systems was developed. Rapid progress in the field of numerical physics-based space environment modeling has led to major developments over the past few years. In this study modeling and analysis of induced geoelectric fields is discussed. Specifically, we focus on the successful incorporation of 3-D EM transfer functions in the modeling of E-fields, and on the analysis of near real-time simulation outputs used in the Solar Shield forecast system. The extended Solar Shield is a collaborative project between DHS, NASA, NOAA, CUA and EPRI.

Tight focusing of higher orders Laguerre-Gaussian modes

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

Savelyev, Dmitry A., E-mail: dmitrey.savelyev@yandex.ru; Khonina, Svetlana N.; Samara State Aerospace University, 34 Moskovskoye Shosse, Samara 443086

2016-04-13

The spatial redistribution of the contribution of different electric field components provides a decrease in the size of the central focal spot for higher orders Laguerre-Gaussian modes. It was shown that when sharply focusing laser beams with vortex or special binary phase plate, a sub-wavelength light localization of separate vector field components is possible for any polarization type. This fact should be considered for the interaction of laser radiation with materials selectively sensitive to lateral and longitudinal components of the electromagnetic field.

A review of the automated detection and classification of acute leukaemia: Coherent taxonomy, datasets, validation and performance measurements, motivation, open challenges and recommendations.

PubMed

Alsalem, M A; Zaidan, A A; Zaidan, B B; Hashim, M; Madhloom, H T; Azeez, N D; Alsyisuf, S

2018-05-01

Acute leukaemia diagnosis is a field requiring automated solutions, tools and methods and the ability to facilitate early detection and even prediction. Many studies have focused on the automatic detection and classification of acute leukaemia and their subtypes to promote enable highly accurate diagnosis. This study aimed to review and analyse literature related to the detection and classification of acute leukaemia. The factors that were considered to improve understanding on the field's various contextual aspects in published studies and characteristics were motivation, open challenges that confronted researchers and recommendations presented to researchers to enhance this vital research area. We systematically searched all articles about the classification and detection of acute leukaemia, as well as their evaluation and benchmarking, in three main databases: ScienceDirect, Web of Science and IEEE Xplore from 2007 to 2017. These indices were considered to be sufficiently extensive to encompass our field of literature. Based on our inclusion and exclusion criteria, 89 articles were selected. Most studies (58/89) focused on the methods or algorithms of acute leukaemia classification, a number of papers (22/89) covered the developed systems for the detection or diagnosis of acute leukaemia and few papers (5/89) presented evaluation and comparative studies. The smallest portion (4/89) of articles comprised reviews and surveys. Acute leukaemia diagnosis, which is a field requiring automated solutions, tools and methods, entails the ability to facilitate early detection or even prediction. Many studies have been performed on the automatic detection and classification of acute leukaemia and their subtypes to promote accurate diagnosis. Research areas on medical-image classification vary, but they are all equally vital. We expect this systematic review to help emphasise current research opportunities and thus extend and create additional research fields. Copyright © 2018 Elsevier B.V. All rights reserved.

Is the First-Year Predictive for Study Success in Subsequent Years? Findings from an Academy of Music

ERIC Educational Resources Information Center

Mennen, Josien; van der Klink, Marcel

2017-01-01

In higher education, departments are under increasing pressure to improve study success. Research in this field focusing on higher music education is scarce. The aim of this study was to gain insight into the predictive capability of the first year for study success of students at an academy of music in subsequent years. Data on study progression…

A Five-Year Study of the First Edition of the Core-Plus Mathematics Curriculum

ERIC Educational Resources Information Center

Schoen, Harold, Ed.; Ziebarth, Steven W., Ed.; Hirsch, Christian R., Ed.; BrckaLorenz, Allison, Ed.

2010-01-01

The study reported in this volume adds to the growing body of evaluation studies that focus on the use of NSF-funded Standards-based high school mathematics curricula. Most previous evaluations have studied the impact of field-test versions of a curriculum. Since these innovative curricula were so new at the time of many of these studies, students…

On production and asymmetric focusing of flat electron beams using rectangular capillary discharge plasmas

DOE PAGES

Bagdasarov, G. A.; Bobrova, N. A.; Boldarev, A. S.; ...

2017-12-27

A method for the asymmetric focusing of electron bunches, based on the active plasma lensing technique is proposed. Our method takes advantage of the strong inhomogeneous magnetic field generated inside the capillary discharge plasma to focus the ultrarelativistic electrons. The plasma and magnetic field parameters inside the capillary discharge are described theoretically and modeled with dissipative magnetohydrodynamic computer simulations enabling analysis of the capillaries of rectangle cross-sections. We could use large aspect ratio rectangular capillaries to transport electron beams with high emittance asymmetries, as well as assist in forming spatially flat electron bunches for final focusing before the interaction point.

On production and asymmetric focusing of flat electron beams using rectangular capillary discharge plasmas

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

Bagdasarov, G. A.; Bobrova, N. A.; Boldarev, A. S.

A method for the asymmetric focusing of electron bunches, based on the active plasma lensing technique is proposed. Our method takes advantage of the strong inhomogeneous magnetic field generated inside the capillary discharge plasma to focus the ultrarelativistic electrons. The plasma and magnetic field parameters inside the capillary discharge are described theoretically and modeled with dissipative magnetohydrodynamic computer simulations enabling analysis of the capillaries of rectangle cross-sections. We could use large aspect ratio rectangular capillaries to transport electron beams with high emittance asymmetries, as well as assist in forming spatially flat electron bunches for final focusing before the interaction point.

Enhanced Axial Resolution of Wide-Field Two-Photon Excitation Microscopy by Line Scanning Using a Digital Micromirror Device.

PubMed

Park, Jong Kang; Rowlands, Christopher J; So, Peter T C

2017-01-01

Temporal focusing multiphoton microscopy is a technique for performing highly parallelized multiphoton microscopy while still maintaining depth discrimination. While the conventional wide-field configuration for temporal focusing suffers from sub-optimal axial resolution, line scanning temporal focusing, implemented here using a digital micromirror device (DMD), can provide substantial improvement. The DMD-based line scanning temporal focusing technique dynamically trades off the degree of parallelization, and hence imaging speed, for axial resolution, allowing performance parameters to be adapted to the experimental requirements. We demonstrate this new instrument in calibration specimens and in biological specimens, including a mouse kidney slice.