The Impact of Farmer Field Schools on Human and Social Capital: A Case Study from Ghana

ERIC Educational Resources Information Center

David, Soniia; Asamoah, Christopher

2011-01-01

Based on a case study of Ghanaian cocoa farmers who attended farmer field schools (FFS), this paper explores the impact of the FFS methodology on farmers' technical knowledge, experimentation, knowledge diffusion, group formation and social skills as a way of assessing whether the relatively high costs associated with the method is justified. We…

A Case Study of Professional Boundary Issues Experienced by Undergraduate Psychology Students in a Supervised Field Experience Course

ERIC Educational Resources Information Center

Sharp, Gwen; Yao, Richard; Cresiski, Robin; Hahn, Kate

2013-01-01

There has been little research on the types of boundary issues encountered in undergraduate psychology field experience courses, despite the increased popularity of such courses. This case study identifies the frequency and types of boundary issues faced by undergraduate psychology students enrolled in such a course, including the most common…

Penetration of Magnetosheath Plasma into Dayside Magnetosphere. 2. ; Magnetic Field in Plasma Filaments

NASA Technical Reports Server (NTRS)

Lyatsky, Wladislaw; Pollock, Craig; Goldstein, Melvyn L.; Lyatskaya, Sonya Inna; Avanov, Levon Albert

2016-01-01

In this paper, we examined plasma structures (filaments), observed in the dayside magnetosphere but containing magnetosheath plasma. These filaments show the stable antisunward motion (while the ambient magnetospheric plasma moved in the opposite direction) and the existence of a strip of magnetospheric plasma, separating these filaments from the magnetosheath. These results, however, contradict both theoretical studies and simulations by Schindler (1979), Ma et al. (1991), Dai and Woodward (1994, 1998), and other researchers, who reported that the motion of such filaments through the magnetosphere is possible only when their magnetic field is directed very close to the ambient magnetic field, which is not the situation that is observed. In this study, we show that this seeming contradiction may be related to different events as the theoretical studies and simulations are related to the case when the filament magnetic field is about aligned with filament orientation, whereas the observations show that the magnetic field in these filaments may be rotating. In this case, the rotating magnetic field, changing incessantly its direction, drastically affects the penetration of plasma filaments into the magnetosphere. In this case, the filaments with rotating magnetic field, even if in each moment it is significantly inclined to the ambient magnetic field, may propagate through the magnetosphere, if their average (for the rotation period) magnetic field is aligned with the ambient magnetic field. This shows that neglecting the rotation of magnetic field in these filaments may lead to wrong results.

Binasal hemianopia.

PubMed

Salinas-Garcia, R F; Smith, J L

1978-09-01

The visual fields of 100 patients referred for neuro-ophthalmologic examination were reviewed; eight cases had binasal visual field defects. Most clinicians have suspected an intracranial cause for such field defects since the classic report of Cushing and Walker in 1912. However, in this study, the cause for the binasal hemianopia was found to be ischemic optic neuropathy in two patients, and one case each of optic nerve drusen, glaucoma, congenital optic nerve pits, and retinitis pigmentosa sine pigmento. Thus 75% of the cases had an intraocular cause for the binasal hemianopia. Two patients had congenital hydrocephalus, and an intracranial basis was thus noted in 25% of these cases. The neurosurgeon should realize that the patient with binasal field defects is much more likely to have an ocular cause than an intracranial one for his problem.

Optimal estimation of spatially variable recharge and transmissivity fields under steady-state groundwater flow. Part 2. Case study

NASA Astrophysics Data System (ADS)

Graham, Wendy D.; Neff, Christina R.

1994-05-01

The first-order analytical solution of the inverse problem for estimating spatially variable recharge and transmissivity under steady-state groundwater flow, developed in Part 1 is applied to the Upper Floridan Aquifer in NE Florida. Parameters characterizing the statistical structure of the log-transmissivity and head fields are estimated from 152 measurements of transmissivity and 146 measurements of hydraulic head available in the study region. Optimal estimates of the recharge, transmissivity and head fields are produced throughout the study region by conditioning on the nearest 10 available transmissivity measurements and the nearest 10 available head measurements. Head observations are shown to provide valuable information for estimating both the transmissivity and the recharge fields. Accurate numerical groundwater model predictions of the aquifer flow system are obtained using the optimal transmissivity and recharge fields as input parameters, and the optimal head field to define boundary conditions. For this case study, both the transmissivity field and the uncertainty of the transmissivity field prediction are poorly estimated, when the effects of random recharge are neglected.

From "fixing women" to "institutional transformation": An ADVANCE case study

NASA Astrophysics Data System (ADS)

Yennello, Sherry; Kaunas, Christine

2015-12-01

The United States' position in the global economy requires an influx of women into science, technology, engineering, and mathematics (STEM) fields in order to remain competitive. Despite this, the representation of women in STEM continues to be low. The National Science Foundation's ADVANCE Program addresses this issue by funding projects that aim to increase the representation of women in academic STEM fields through transformation of institutional structures that impede women's progress in academic STEM fields. This paper includes a case study of the Texas A&M University ADVANCE Program.

Redefining University Roles in Regional Economies: A Case Study of University-Industry Relations and Academic Organization in Nanotechnology

ERIC Educational Resources Information Center

Sa, Creso M.

2011-01-01

The emerging field of nanotechnology has created a new frontier for the convergence of university and industrial research. In the United States, major federal investments provided a massive boom for this field over the decade. This paper reports on a case study of how the University at Albany came to establish the first college of nanotechnology…

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…

The Interplanetary Magnetic Field and Magnetospheric Current Systems

NASA Technical Reports Server (NTRS)

El-Alaoui, Mostafa

2003-01-01

We have performed systematic global magnetohydrodynamic (MHD) simulation studies driven by an idealized time series of solar wind parameters to establish basic cause and effect relationships between the solar wind variations and the ionosphere parameters. We studied six cases in which the interplanetary magnetic field (IMF) rotated from southward to northward in one minute. In three cases (cases A, B, and C) we ran five hours of southward IMF with Beta(sub Zeta) = 5 nT, followed by five hours of northward IMF with Beta(sub Zeta) = 5 nT. In the other three cases (cases D, E, and F) the magnetic field magnitude was increased to 10 nT. The solar wind parameters were: For cases A and D a density of 5 cm(exp -3), a thermal pressure of 3.3 nPa, and a solar wind speed 375 km/s, for cases B and E a density of 10 cm(exp -3), a thermal pressure of 9.9 nPa, and a solar wind speed 420 km/s, while for cases C and F a density of 15 cm(exp -3), a thermal pressure of 14.9 nPa, and a solar wind speed of 600 km/s.

Stability of the line preserving flows

NASA Astrophysics Data System (ADS)

Figura, Przemysław

2017-11-01

We examine the equations that are used to describe flows which preserve field lines. We study what happens if we introduce perturbations to the governing equations. The stability of the line preserving flows in the case of the magneto-fluids permeated by magnetic fields is strictly connected to the non-null magnetic reconnection processes. In most of our study we use the Euler potential representation of the external magnetic field. We provide general expressions for the perturbations of the Euler potentials that describe the magnetic field. Similarly, we provide expressions for the case of steady flow as well as we obtain certain conditions required for the stability of the flow. In addition, for steady flows we formulate conditions under which the perturbations of the external field are negligible and the field may be described by its initial unperturbed form. Then we consider the flow equation that transforms quantities from the laboratory coordinate system to the related external field coordinate system. We introduce perturbations to the equation and obtain its simplified versions for the case of a steady flow. For a given system, use of this method allows us to simplify the considerations provided that some part of the system may be described as a perturbation. Next, to study regions favourable for the magnetic reconnection to occur we introduce a deviation vector to the basic line preserving flows condition equation. We provide expressions of the vector for some simplifying cases. This method allows us to examine if given perturbations either stabilise the system or induce magnetic reconnection. To illustrate some of our results we study two examples, namely a simple laboratory plasma flow and a simple planetary magnetosphere model.

Myelogenous leukemia and electric blanket use.

PubMed

Preston-Martin, S; Peters, J M; Yu, M C; Garabrant, D H; Bowman, J D

1988-01-01

In a case-control study of adult acute and chronic myelogenous leukemia in Los Angeles County, we tested the hypothesis that excess exposure to electromagnetic fields from electric blankets was associated with risk of leukemia. We did this by studying 116 cases of acute myelogenous leukemia (AML) and 108 cases of chronic myelogenous leukemia (CML) along with matched neighborhood controls. The cases and controls were queried as to electric blanket use and the risks computed. For AML the risk was 0.9 (95% CI 0.5-1.6) and for CML the risk was 0.8 (95% CI 0.4-1.6). Cases did not differ from controls by duration of use, year of first regular use, year since last use, or socioeconomic status. Our best estimates of exposure indicate that electric blanket use increases overall exposure to electric fields by less than 50% and magnetic fields by less than 100%. We conclude that there is no major leukemogenic risk associated with electric blanket use in Los Angeles County.

77 FR 38282 - Final Test Guidelines; OCSPP 850 Series; Notice of Availability

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-27

... conditions. EPA is changing the title of OPPTS 850.4450 ``Aquatic Plants Field Study, Tier III'' test....4300 ``Terrestrial Plants Field Study, Tier III'' test guideline. Public Draft OPPTS 850.4025 ``Target..., OCSPP 850.4300 ``Terrestrial Plants Field Study.'' The target area test guideline covers a special case...

High-time resolution measurements of upstream magnetic field and plasma conditions during flux transfer events at the Earth's dayside magnetopause

NASA Technical Reports Server (NTRS)

Jacob, Jamey D.; Carrell, Cynthia

1993-01-01

We present preliminary results of a study of upstream magnetic field and plasma conditions measured by IRM during flux transfer events observed at the Earth's magnetopause by CCE. This study was designed to determine the importance of various upstream factors in the formation of bipolar magnetic field signatures called flux transfer events (FTEs). Six FTE encounters were examined. In three cases, the two satellites were on similar magnetic field lines. Preliminary investigation showed that fluctuations occurred in the Bz component of the interplanetary magnetic field (IMF) resulting in a southward field preceding the FTE in all three of these cases. In two of these cases, the changes were characterized by a distinct rotation from a strong southward to a strong northward field. There were also accompanying changes in the dynamic and thermal pressure in the solar wind immediately before the FTE was encountered. Examination of the 3D plasma distributions showed that these pulses were due to the addition of energetic upstreaming foreshock particles. There were no consistent changes in either Bz or the plasma pressure at IRM for the three events when the satellites were not connected by the IMF.

Attractor behaviour in multifield inflation

NASA Astrophysics Data System (ADS)

Carrilho, Pedro; Mulryne, David; Ronayne, John; Tenkanen, Tommi

2018-06-01

We study multifield inflation in scenarios where the fields are coupled non-minimally to gravity via ξI(phiI)n gμνRμν, where ξI are coupling constants, phiI the fields driving inflation, gμν the space-time metric, Rμν the Ricci tensor, and n>0. We consider the so-called α-attractor models in two formulations of gravity: in the usual metric case where Rμν=Rμν(gμν), and in the Palatini formulation where Rμν is an independent variable. As the main result, we show that, regardless of the underlying theory of gravity, the field-space curvature in the Einstein frame has no influence on the inflationary dynamics at the limit of large ξI, and one effectively retains the single-field case. However, the gravity formulation does play an important role: in the metric case the result means that multifield models approach the single-field α-attractor limit, whereas in the Palatini case the attractor behaviour is lost also in the case of multifield inflation. We discuss what this means for distinguishing between different models of inflation.

Case Studies for Educational Leadership: Solving Administrative Dilemmas

ERIC Educational Resources Information Center

Midlock, Stephen F.

2010-01-01

"Case Studies for Educational Leadership" gives educational leadership students an opportunity to project themselves into real-life administrative situations and prepare for their future positions in the field. Each case study contained in this practical first edition book asks students to analyze complex problems, consider the moral ramifications…

A Case Study of "Empathetic Teaching Artistry"

ERIC Educational Resources Information Center

Risner, Doug

2014-01-01

This case study is one of twenty cases derived from Anderson and Risner's international study of teaching artists in dance, and theatre, which investigated participants' (n=172) artistic and academic preparation in dance, and theatre, initial entry into the teaching artist field, rewards, challenges, and obstacles in participants' work, artists'…

Case Studies in the Field of Marketing Education: Learner Impact, Case Performance, and Cost Efficiency

ERIC Educational Resources Information Center

Spais, George S.

2005-01-01

The major objective of this study is to identify a methodology that will help educators in marketing to efficiently manage the design, impact, and cost of case studies. It is my intention is to examine the impact of case study characteristics in relation to the degree of learner involvement in the learning process. The author proposes that…

Web-Based Case Conferencing for Preservice Teacher Education: Electronic Discourse from the Field.

ERIC Educational Resources Information Center

Bonk, Curtis Jay; Malikowski, Steve; Angeli, Charoula; East, Judy

1998-01-01

The purpose of this study was to foster preservice teacher learning of educational psychology by creating a Web-based learning community using actual case situations experienced during field observations. Participants (146 undergraduate students) were assigned to two electronic-conferencing groups where they generated teaching vignettes related to…

Leukemia and brain tumors in Norwegian railway workers, a nested case-control study.

PubMed

Tynes, T; Jynge, H; Vistnes, A I

1994-04-01

In an attempt to assess whether exposure to electromagnetic fields on Norwegian railways induces brain tumors or leukemia, the authors conducted a nested case-control study of railway workers based on incident cases from the Cancer Registry of Norway in a cohort of 13,030 male Norwegian railway workers who had worked on either electric or non-electric railways. The cohort comprised railway line, outdoor station, and electricity workers. The case series comprised 39 men with brain tumors and 52 men with leukemia (follow-up, 1958-1990). Each case was matched on age with four or five controls selected from the same cohort. The exposure of each study subject to electric and magnetic fields was evaluated from cumulative exposure measures based on present measurements and historical data. Limited information on potential confounders such as creosote, solvents, and herbicides was also collected; information on whether the subject had smoked was obtained by interviews with the subjects or work colleagues. The case-control analysis showed that men employed on electric railways, compared with non-electric ones, had an odds ratio for leukemia of 0.70 (adjusted for smoking) and an odds ratio for brain tumor of 0.87. No significant trend was shown for exposure to either magnetic or electric fields. These results do not support an association between exposure to 16 2/3-Hertz electric or magnetic fields and the risk for leukemia or brain tumors.

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

NASA Technical Reports Server (NTRS)

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

1990-01-01

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

Gravitational scattering of electromagnetic radiation

NASA Technical Reports Server (NTRS)

Brooker, J. T.; Janis, A. I.

1980-01-01

The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.

ELF field in the proximity of complex power line configuration measurement procedures.

PubMed

Benes, M; Comelli, M; Villalta, R

2006-01-01

The issue of how to measure magnetic induction fields generated by various power line configurations, when there are several power lines that run across the same exposure area, has become a matter of interest and study within the Regional Environment Protection Agency of Friuli Venezia Giulia. In classifying the various power line typologies the definition of double circuit line was given: in this instance the magnetic field is determined by knowing the electrical and geometric parameters of the line. In the case of independent lines instead, the field is undetermined. It is therefore pointed out how, in the latter case, extracting previsional information from a set of measurements of the magnetic field alone is impossible. Making measurements throughout the territory of service has in several cases offered the opportunity to define standard operational procedures.

Enhancing the quality of case studies in health services research.

PubMed Central

Yin, R K

1999-01-01

OBJECTIVE: To provide guidance on improving the quality of case studies in health services research. DATA SOURCES: Secondary data, drawing from previous case study research. RESEARCH DESIGN: Guidance is provided to two audiences: potential case study investigators (eight items) and reviewers of case study proposals (four additional items). PRINCIPAL FINDINGS: The guidance demonstrates that many operational steps can be undertaken to improve the quality of case studies. These steps have been a hallmark of high-quality case studies in related fields but have not necessarily been practiced in health services research. CONCLUSIONS: Given higher-quality case studies, the case study method can become a valuable tool for health services research. Images Figure 3 PMID:10591280

[Flomoxef in the pediatric surgical field].

PubMed

Yura, J; Shimizu, Y; Hashimoto, T; Nakamura, T; Otobe, Y; Minami, M

1991-11-01

Basic and clinical studies of flomoxef (6315-S, FMOX) were performed in the pediatric surgical field. The results obtained are summarized as follows: 1. FMOX was administered to 7 pediatric patients with biliary atresia (FMOX 20 mg/kg, i.v.d.). Peak biliary levels of FMOX were obtained at 1 hour after finishing administration by drip infusion, and were higher than those in blood 1 hours after finishing administration by drip infusion. 2. Urinary excretion was excellent, and urinary recovery rates were 57.8-97.8%. 3. FMOX was administered to 5 patients in the pediatric surgical field. One case was phlegmon, and other 4 cases were premature babies for postoperative prophylactic use. Clinical results were excellent in 1 case, good in 4 cases, with an overall efficacy rate of 100%. No clinical and laboratory side effects due to the administration FMOX were observed. It was concluded that FMOX was a safe and effective antibiotic in the pediatric surgical field.

Geomagnetic field models for satellite angular motion studies

NASA Astrophysics Data System (ADS)

Ovchinnikov, M. Yu.; Penkov, V. I.; Roldugin, D. S.; Pichuzhkina, A. V.

2018-03-01

Four geomagnetic field models are discussed: IGRF, inclined, direct and simplified dipoles. Geomagnetic induction vector expressions are provided in different reference frames. Induction vector behavior is compared for different models. Models applicability for the analysis of satellite motion is studied from theoretical and engineering perspectives. Relevant satellite dynamics analysis cases using analytical and numerical techniques are provided. These cases demonstrate the benefit of a certain model for a specific dynamics study. Recommendations for models usage are summarized in the end.

Spinor Field Nonlinearity and Space-Time Geometry

NASA Astrophysics Data System (ADS)

Saha, Bijan

2018-03-01

Within the scope of Bianchi type VI,VI0,V, III, I, LRSBI and FRW cosmological models we have studied the role of nonlinear spinor field on the evolution of the Universe and the spinor field itself. It was found that due to the presence of non-trivial non-diagonal components of the energy-momentum tensor of the spinor field in the anisotropic space-time, there occur some severe restrictions both on the metric functions and on the components of the spinor field. In this report we have considered a polynomial nonlinearity which is a function of invariants constructed from the bilinear spinor forms. It is found that in case of a Bianchi type-VI space-time, depending of the sign of self-coupling constants, the model allows either late time acceleration or oscillatory mode of evolution. In case of a Bianchi VI 0 type space-time due to the specific behavior of the spinor field we have two different scenarios. In one case the invariants constructed from bilinear spinor forms become trivial, thus giving rise to a massless and linear spinor field Lagrangian. This case is equivalent to the vacuum solution of the Bianchi VI 0 type space-time. The second case allows non-vanishing massive and nonlinear terms and depending on the sign of coupling constants gives rise to accelerating mode of expansion or the one that after obtaining some maximum value contracts and ends in big crunch, consequently generating space-time singularity. In case of a Bianchi type-V model there occur two possibilities. In one case we found that the metric functions are similar to each other. In this case the Universe expands with acceleration if the self-coupling constant is taken to be a positive one, whereas a negative coupling constant gives rise to a cyclic or periodic solution. In the second case the spinor mass and the spinor field nonlinearity vanish and the Universe expands linearly in time. In case of a Bianchi type-III model the space-time remains locally rotationally symmetric all the time, though the isotropy of space-time can be attained for a large proportionality constant. As far as evolution is concerned, depending on the sign of coupling constant the model allows both accelerated and oscillatory mode of expansion. A negative coupling constant leads to an oscillatory mode of expansion, whereas a positive coupling constant generates expanding Universe with late time acceleration. Both deceleration parameter and EoS parameter in this case vary with time and are in agreement with modern concept of space-time evolution. In case of a Bianchi type-I space-time the non-diagonal components lead to three different possibilities. In case of a full BI space-time we find that the spinor field nonlinearity and the massive term vanish, hence the spinor field Lagrangian becomes massless and linear. In two other cases the space-time evolves into either LRSBI or FRW Universe. If we consider a locally rotationally symmetric BI( LRSBI) model, neither the mass term nor the spinor field nonlinearity vanishes. In this case depending on the sign of coupling constant we have either late time accelerated mode of expansion or oscillatory mode of evolution. In this case for an expanding Universe we have asymptotical isotropization. Finally, in case of a FRW model neither the mass term nor the spinor field nonlinearity vanishes. Like in LRSBI case we have either late time acceleration or cyclic mode of evolution. These findings allow us to conclude that the spinor field is very sensitive to the gravitational one.

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

Case studies approach for an undergraduate astrobiology course

NASA Astrophysics Data System (ADS)

Burko, Lior M.; Enger, Sandra

2013-04-01

Case studies is a well known and widely used method in law schools, medical schools, and business schools, but relatively little used in physics or astronomy courses. We developed an astrobiology course based strongly on the case studies approach, and after teaching it first at the University of Alabama in Huntsville, we have adapted it and are now teaching it at Alabama A&M University, a HBCU. The case studies approach uses several well tested and successful teaching methods - including group work, peer instruction, current interest topics, just-in-time teaching, &c. We have found that certain styles of cases are more popular among students than other styles, and will revise our cases to reflect such student preferences. We chose astrobiology -- an inherently multidisciplinary field -- because of the popularity of the subject matter, its frequent appearance in the popular media (news stories about searches for life in the universe, the discovery of Earth-like exoplanets, etc, in addition to SciFi movies and novels), and the rapid current progress in the field. In this talk we review briefly the case studies method, the styles of cases used in our astrobiology course, and student response to the course as found in our assessment analysis.

Rethinking a Case Study Method in Educational Research: A Comparative Analysis Method in Qualitative Research

ERIC Educational Resources Information Center

Murakami, Yusuke

2013-01-01

There are two types of qualitative research that analyze a small number of cases or a single case: idiographic differentiation and nomothetic/generalization. There are few case studies of generalization. This is because theoretical inclination is weak in the field of education, and the binary framework of quantitative versus qualitative research…

High apoptotic index in urine cytology is associated with high-grade urothelial carcinoma.

PubMed

Yang, Chi-Shun; Chen, Shaoxiong; Cramer, Harvey M; Wu, Howard H

2016-08-01

The significance of apoptosis and its association with high-grade urothelial carcinoma (HGUC) in urine cytology has yet to be determined. A computerized search of the study laboratory information system was performed over a 3-year period for all urine cytology specimens processed using the SurePath liquid-based preparation technique. Only those cases with correlating surgical pathology obtained within 6 months after the urine cytologic samples were included in the current study. Cases from ileal conduit samples were excluded. A semiquantitative numerical scoring system (apoptotic index) was used to assess the amount of pyknosis or karyorrhexis, with 0 indicating none, 1 indicating < 10 per 10 high-power fields, 2 indicating 10 to 30 per 10 high-power fields, and 3 indicating > 30 per 10 high-power fields. Statistical analysis using the Pearson chi-square test was performed. A total of 228 cases including 105 benign cases, 79 cases of HGUC, and 44 cases of low-grade urothelial carcinoma (LGUC) diagnosed on follow-up surgical pathology were selected. A score of 0 was observed in 70 benign, 11 HGUC, and 8 LGUC cases; a score of 1 was observed in 31 benign, 21 HGUC, and 23 LGUC cases; a score of 2 was observed in 3 benign, 27 HGUC, and 9 LGUC cases; and a score of 3 was observed in 1 benign, 20 HGUC, and 4 LGUC cases. Excluding ileal conduit urine specimens, the finding of a high apoptotic index (score ≥ 2) with the presence of pyknosis or karyorrhexis in ≥10 per 10 high-power fields in the urine cytology appears to be significantly associated with HGUC (P<.05). Cancer Cytopathol 2016;124:546-51. © 2016 American Cancer Society. © 2016 American Cancer Society.

Childhood Leukemia and 50 Hz Magnetic Fields: Findings from the Italian SETIL Case-Control Study

PubMed Central

Salvan, Alberto; Ranucci, Alessandra; Lagorio, Susanna; Magnani, Corrado

2015-01-01

We report on an Italian case-control study on childhood leukemia and exposure to extremely low frequency magnetic fields (ELF-MF). Eligible for inclusion were 745 leukemia cases, aged 0–10 years at diagnosis in 1998–2001, and 1475 sex- and age-matched population controls. Parents of 683 cases and 1044 controls (92% vs. 71%) were interviewed. ELF-MF measurements (24–48 h), in the child’s bedroom of the dwelling inhabited one year before diagnosis, were available for 412 cases and 587 controls included in the main conditional regression analyses. The magnetic field induction was 0.04 μT on average (geometric mean), with 0.6% of cases and 1.6% of controls exposed to >0.3 μT. The impact of changes in the statistical model, exposure metric, and data-set restriction criteria was explored via sensitivity analyses. No exposure-disease association was observed in analyses based on continuous exposure, while analyses based on categorical variables were characterized by incoherent exposure-outcome relationships. In conclusion, our results may be affected by several sources of bias and they are noninformative at exposure levels >0.3 μT. Nonetheless, the study may contribute to future meta- or pooled analyses. Furthermore, exposure levels among population controls are useful to estimate attributable risk. PMID:25689995

Cauchy horizon stability in a collapsing spherical dust cloud: II. Energy bounds for test fields and odd-parity gravitational perturbations

NASA Astrophysics Data System (ADS)

Ortiz, Néstor; Sarbach, Olivier

2018-01-01

We analyze the stability of the Cauchy horizon associated with a globally naked, shell-focussing singularity arising from the complete gravitational collapse of a spherical dust cloud. In a previous work, we have studied the dynamics of spherical test scalar fields on such a background. In particular, we proved that such fields cannot develop any divergences which propagate along the Cauchy horizon. In the present work, we extend our analysis to the more general case of test fields without symmetries and to linearized gravitational perturbations with odd parity. To this purpose, we first consider test fields possessing a divergence-free stress-energy tensor satisfying the dominant energy condition, and we prove that a suitable energy norm is uniformly bounded in the domain of dependence of the initial slice. In particular, this result implies that free-falling observers co-moving with the dust particles measure a finite energy of the field, even as they cross the Cauchy horizon at points lying arbitrarily close to the central singularity. Next, for the case of Klein–Gordon fields, we derive point-wise bounds from our energy estimates which imply that the scalar field cannot diverge at the Cauchy horizon, except possibly at the central singular point. Finally, we analyze the behaviour of odd-parity, linear gravitational and dust perturbations of the collapsing spacetime. Similarly to the scalar field case, we prove that the relevant gauge-invariant combinations of the metric perturbations stay bounded away from the central singularity, implying that no divergences can propagate in the vacuum region. Our results are in accordance with previous numerical studies and analytic work in the self-similar case.

Cholera outbreak in Homa Bay County, Kenya, 2015.

PubMed

Githuku, Jane Njoki; Boru, Waqo Gufu; Hall, Casey Daniel; Gura, Zeinab; Oyugi, Elvis; Kishimba, Rogath Saika; Semali, Innocent; Farhat, Ghada Nadim; Mattie Park, Meeyoung

2017-01-01

Cholera is among the re-emerging diseases in Kenya. Beginning in December 2014, a persistent outbreak occurred involving 29 out of the 47 countries. Homa Bay County in Western Kenya was among the first counties to report cholera cases from January to April 2015. This case study is based on an outbreak investigation conducted by FELTP residents in Homa Bay County in February 2015. It simulates an outbreak investigation including laboratory confirmation, active case finding, descriptive epidemiology and implementation of control measures. This case study is designed for the training of basic level field epidemiology trainees or any other health care workers working in public health-related fields. It can be administered in 2-3 hours. Used as adjunct training material, the case study provides the trainees with competencies in investigating an outbreak in preparation for the actual real-life experience of such outbreaks.

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…

Military Hydrology. Report 12. Case Study Evaluation of Alternative Dam-Breach Flood Wave Methods. Volume 1. Main Report.

DTIC Science & Technology

1986-11-01

Report Organization. .................... 7 *PART 11: CASE STUDIES .......................... 9 Teton Dam Failure Flood. ...................... 9...channel, (3) Laurel Run Dam , and (4) Stillhouse Hollow Dam . The Laurel Run and Teton case studies involved field data sets from actual dam failures. The...hypothetical prismatic channel case study used the Teton reservoir and dam data but replaced the complex Teton Valley geometry with a prismatic channel

Individualization of Instruction: High School Chemistry - A Case Study.

ERIC Educational Resources Information Center

Altieri, Donald; Becht, Paul

This publication contains information on the individualization of instruction in high school chemistry in the form of a case study. The subject of the case study is the P. K. Yonge Laboratory School of the University of Florida, Gainesville. The instructional model, however, was also field-tested in 18 schools during 1971-72 and 1972-73. The…

Los Angeles study of residential magnetic fields and childhood brain tumors.

PubMed

Preston-Martin, S; Navidi, W; Thomas, D; Lee, P J; Bowman, J; Pogoda, J

1996-01-15

A measurement study of residential magnetic fields and brain tumors in children that was added onto an ongoing case-control interview study in Los Angeles County, California, include 298 children under age 20 years with a primary brain tumor diagnosed from 1984 to 1991 and 298 control children identified by random digit dialing. Magnetic fields were determined for all Los Angeles homes where these 596 children lived from conception to diagnosis (1,131 homes) by mapping and coding the wiring configurations outside the home and by taking a series of exterior spot and profile measurements. In addition, for a subset of subjects (35%; 211 homes) 24-hour measurements were taken in the child's room and one other room. Although measured fields are consistently highest in the highest of the five wire code categories, fields in homes in this category are much lower in Los Angeles than in Denver, where the code originated. Brain tumor risk appears not to relate to measured fields inside (p for trend for child's room = 0.98) or outside (p for trend for front wall = 0.82) the home. An apparent increase in risk among children living at diagnosis in homes with underground wiring appears to be an artifact introduced by using current controls for historical cases because this apparent excess risk disappeared in an analysis restricted to the later years of the study when cases and controls were accrued concurrently. Our study does not show an overall association of pediatric brain tumors with measured fields, with "very high" wiring configurations, or with any of several other potential sources of exposure, such as use of various electrical appliances, but the prevalence of high fields (> 2 mG) and very high fields (> 3 mG) in Los Angeles homes was too low to detect a moderate effect of the magnitude reported in other studies.

Uniform refraction in negative refractive index materials.

PubMed

Gutiérrez, Cristian E; Stachura, Eric

2015-11-01

We study the problem of constructing an optical surface separating two homogeneous, isotropic media, one of which has a negative refractive index. In doing so, we develop a vector form of Snell's law, which is used to study surfaces possessing a certain uniform refraction property, in both the near- and far-field cases. In the near-field problem, unlike the case when both materials have positive refractive indices, we show that the resulting surfaces can be neither convex nor concave.

Bound states for an induced electric dipole in the presence of an azimuthal magnetic field and a disclination

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

Bakke, K.

2010-09-15

Based on the Wei-Han-Wei setup [H. Wei, R. Han, and X. Wei, Phys. Rev. Lett. 75, 2071 (1995)], where a neutral particle with an induced electric dipole moment interacts with a configuration of crossed electric and magnetic fields, in this paper we study the bound states that arise when we change the Wei-Han-Wei field configuration and consider a field configuration of crossed azimuthal magnetic field and a radial electric field. Moreover, we consider here a spin-half neutral particle and the presence of a linear topological defect called disclination. We obtain the bound states in two distinct cases: in the firstmore » case, we consider that the wave function of the neutral particle is well-behaved at the origin and vanishes at the asymptotic limit; in the second case, we consider the neutral particle confined to a parabolic potential like a quantum dot.« less

Anisotropic Bianchi Type-I and Type-II Bulk Viscous String Cosmological Models Coupled with Zero Mass Scalar Field

NASA Astrophysics Data System (ADS)

Venkateswarlu, R.; Sreenivas, K.

2014-06-01

The LRS Bianchi type-I and type-II string cosmological models are studied when the source for the energy momentum tensor is a bulk viscous stiff fluid containing one dimensional strings together with zero-mass scalar field. We have obtained the solutions of the field equations assuming a functional relationship between metric coefficients when the metric is Bianchi type-I and constant deceleration parameter in case of Bianchi type-II metric. The physical and kinematical properties of the models are discussed in each case. The effects of Viscosity on the physical and kinematical properties are also studied.

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

NASA Technical Reports Server (NTRS)

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

2009-01-01

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

Case study of the use of pulsed field gel electrophoresis in the detection of a food-borne outbreak.

PubMed

De Lappe, Niall; Cormican, Martin

2015-01-01

In early July 2008, a cluster of six Salmonella Agona was identified in the Republic of Ireland. A dispersed, common source outbreak was suspected. Later in July a further case was identified and the Health Protection Agency in the UK indicated that they had 32 cases of S. Agona since Feb 2008. This chapter discusses how pulsed field gel electrophoresis was used to help confirm an outbreak and to trace the source of the outbreak.

SABRE observations of Pi2 pulsations: case studies

NASA Astrophysics Data System (ADS)

Bradshaw, E. G.; Lester, M.

1997-01-01

The characteristics of substorm-associated Pi2 pulsations observed by the SABRE coherent radar system during three separate case studies are presented. The SABRE field of view is well positioned to observe the differences between the auroral zone pulsation signature and that observed at mid-latitudes. During the first case study the SABRE field of view is initially in the eastward electrojet, equatorward and to the west of the substorm-enhanced electrojet current. As the interval progresses, the western, upward field-aligned current of the substorm current wedge moves westward across the longitudes of the radar field of view. The westward motion of the wedge is apparent in the spatial and temporal signatures of the associated Pi2 pulsation spectra and polarisation sense. During the second case study, the complex field-aligned and ionospheric currents associated with the pulsation generation region move equatorward into the SABRE field of view and then poleward out of it again after the third pulsation in the series. The spectral content of the four pulsations during the interval indicate different auroral zone and mid-latitude signatures. The final case study is from a period of low magnetic activity when SABRE observes a Pi2 pulsation signature from regions equatorward of the enhanced substorm currents. There is an apparent mode change between the signature observed by SABRE in the ionosphere and that on the ground by magnetometers at latitudes slightly equatorward of the radar field of view. The observations are discussed in terms of published theories of the generation mechanisms for this type of pulsation. Different signatures are observed by SABRE depending on the level of magnetic activity and the position of the SABRE field of view relative to the pulsation generation region. A twin source model for Pi2 pulsation generation provides the clearest explanation of the signatures observed Acknowledgements. The authors are grateful to Prof. D. J. Southwood (Imperial College, London), J. C. Samson (University of Alberta, Edmonton), L. J. Lanzerotti (AT&T Bell Laboratories), A. Wolfe (New York City Technical College) and to Dr. M. Vellante (University of LÁquila) for helpful discussions. They also thank Dr. A. Meloni (Istituto Nazionale di Geofisica, Roma) who made available geomagnetic field observations from LÁquila Geomagnetic Observatory. This research activity at LÁquila is supported by MURST (40% and 60% contracts) and by GIFCO/CNR. Topical Editor K.-H. Glaßmeier thanks C. Waters and S. Fujita for their help in evaluating this paper.-> Correspondence to :P. Francia->

Lessons from a Dominican Republic Field Study

ERIC Educational Resources Information Center

Gunter, Michael M., Jr.

2010-01-01

Utilizing student-centered pedagogy, this case study explores an increasingly prominent and instructive addition to traditional academic coursework--the field study experience. This is particularly true in the arena of environmental education where students learn best by experiencing environmental problems first-hand and then interacting with…

IVHS Institutional Issues and Case Studies: Transcom/Transmit Case Study

DOT National Transportation Integrated Search

1994-04-01

The Transportation Operations Coordinating Committee (TRANSCOM) is a coalition of 15 traffic, transit, and police agencies in the New York, New Jersey, and Connecticut metropolitan area. TRANSCOM's IVHS operational field test, the TRANSCOM System for...

Treatment planning for SBRT using automated field delivery: A case study

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

Ritter, Timothy A., E-mail: timritte@med.umich.edu; Department of Radiation Oncology, Veterans Affairs Ann Arbor Health Care System, Ann Arbor, MI; Owen, Dawn

Stereotactic body radiation therapy (SBRT) treatment planning and delivery can be accomplished using a variety of techniques that achieve highly conformal dose distributions. Herein, we describe a template-based automated treatment field approach that enables rapid delivery of more than 20 coplanar fields. A case study is presented to demonstrate how modest adaptations to traditional SBRT planning can be implemented to take clinical advantage of this technology. Treatment was planned for a left-sided lung lesion adjacent to the chest wall using 25 coplanar treatment fields spaced at 11° intervals. The plan spares the contralateral lung and is in compliance with themore » conformality standards set forth in Radiation Therapy and Oncology Group protocol 0915, and the dose tolerances found in the report of the American Association of Physicists in Medicine Task Group 101. Using a standard template, treatment planning was accomplished in less than 20 minutes, and each 10 Gy fraction was delivered in approximately 5.4 minutes. For those centers equipped with linear accelerators capable of automated treatment field delivery, the use of more than 20 coplanar fields is a viable SBRT planning approach and yields excellent conformality and quality combined with rapid planning and treatment delivery. Although the case study discusses a laterally located lung lesion, this technique can be applied to centrally located tumors with similar results.« less

The effect of guide-field and boundary conditions on collisionless magnetic reconnection in a stressed X-point collapse

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

Graf von der Pahlen, J.; Tsiklauri, D.

2014-01-15

Works of Tsiklauri and Haruki [Phys. Plasmas 15, 102902 (2008); 14, 112905 (2007)] are extended by inclusion of the out-of-plane magnetic (guide) field. In particular, magnetic reconnection during collisionless, stressed X-point collapse for varying out-of-plane guide-fields is studied using a kinetic, 2.5D, fully electromagnetic, relativistic particle-in-cell numerical code. For zero guide-field, cases for both open and closed boundary conditions are investigated, where magnetic flux and particles are lost and conserved, respectively. It is found that reconnection rates, out-of-plane currents and density in the X-point increase more rapidly and peak sooner in the closed boundary case, but higher values are reachedmore » in the open boundary case. The normalized reconnection rate is fast: 0.10-0.25. In the open boundary case it is shown that an increase of guide-field yields later onsets in the reconnection peak rates, while in the closed boundary case initial peak rates occur sooner but are suppressed. The reconnection current changes similarly with increasing guide-field; however for low guide-fields the reconnection current increases, giving an optimal value for the guide-field between 0.1 and 0.2 times the in-plane field in both cases. Also, in the open boundary case, it is found that for guide-fields of the order of the in-plane magnetic field, the generation of electron vortices occurs. Possible causes of the vortex generation, based on the flow of decoupled particles in the diffusion region and localized plasma heating, are discussed. Before peak reconnection onset, oscillations in the out-of-plane electric field at the X-point are found, ranging in frequency from approximately 1 to 2 ω{sub pe} and coinciding with oscillatory reconnection. These oscillations are found to be part of a larger wave pattern in the simulation domain. Mapping the out-of-plane electric field along the central lines of the domain over time and applying a 2D Fourier transform reveal that the waves predominantly correspond to the ordinary and the extraordinary mode and hence may correspond to observable radio waves such as solar radio burst fine structure spikes.« less

Wage Differentials by Field of Study--The Case of German University Graduates

ERIC Educational Resources Information Center

Grave, Barbara S.; Goerlitz, Katja

2012-01-01

Using data on German university graduates, this paper analyzes wage differentials by field of study at labor market entry and five to six years later. At both points of time, graduates from arts/humanities have lower average monthly wages compared to other fields. Blinder-Oaxaca decompositions show that these wage differentials can be explained…

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

ERIC Educational Resources Information Center

Malewski, Erik; Sharma, Suniti; Phillion, JoAnn

2012-01-01

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

Assessment of Reliable Change Using 95% Credible Intervals for the Differences in Proportions: A Statistical Analysis for Case-Study Methodology

ERIC Educational Resources Information Center

Unicomb, Rachael; Colyvas, Kim; Harrison, Elisabeth; Hewat, Sally

2015-01-01

Purpose: Case-study methodology studying change is often used in the field of speech-language pathology, but it can be criticized for not being statistically robust. Yet with the heterogeneous nature of many communication disorders, case studies allow clinicians and researchers to closely observe and report on change. Such information is valuable…

Ultra-wide-field and autofluorescence imaging of choroidal dystrophies.

PubMed

Yuan, Alex; Kaines, Andrew; Jain, Atul; Reddy, Shantan; Schwartz, Steven D; Sarraf, David

2010-10-28

The authors retrospectively identified 2 cases of gyrate atrophy, 3 cases of choroideremia, and 1 case of the carrier state of choroideremia who underwent ultra-wide-field fundus photography and fluorescein angiography. The findings were studied and compared to standard fundus photography and fluorescein angiography. Gyrate atrophy demonstrated a diffuse confluent extent of chorioretinal atrophy extending from the anterior to the posterior pole to the periphery. Choroideremia demonstrated a patchy irregular pattern of chorioretinal atrophy extending from the posterior pole to the periphery. Peripheral reticular degeneration without chorioretinal atrophy was appreciated in the carrier state. Ultra-wide-field imaging of these choroidal dystrophies demonstrated distinctive patterns that may aid in their identification and diagnosis. Copyright 2010, SLACK Incorporated.

Doing Case Study Research: A Practical Guide for Beginning Researchers. Third Edition

ERIC Educational Resources Information Center

Hancock, Dawson R.; Algozzine, Bob

2016-01-01

Reflecting recent knowledge and developments in the field, this very practical, easy-to-use guide emphasizes learning how to do case study research--from the first step of deciding whether a case study is the way to go to the last step of verifying and confirming findings before disseminating them. The authors show students how to determine an…

A Case Study in Elementary Statistics: The Florida Panther Population

ERIC Educational Resources Information Center

Lazowski, Andrew; Stopper, Geffrey

2013-01-01

We describe a case study that was created to intertwine the fields of biology and mathematics. This project is given in an elementary probability and statistics course for non-math majors. Some goals of this case study include: to expose students to biology in a math course, to apply probability to real-life situations, and to display how far a…

Corporate Information Management: A Case Study

DTIC Science & Technology

1991-03-01

SUBJECT TERMS ( FIELD GROUP SUB-GROUP ICorporate Information Management (CIM), Case study, Strategic level decision making, Department Of Defense. 19...ABSTRACT ( This thesis documents in a case format the events, environment and decisions in the genesis and evolution of the Department of Defense’s...case format the events, environment and decisions in the genesis and evolution of the Department of Defense’s Corporate Information Management

[Case and studies].

PubMed

Schubert, András

2015-11-15

Case studies and case reports form an important and ever growing part of scientific and scholarly literature. The paper deals with the share and citation rate of these publication types on different fields of research. In general, evidence seems to support the opinion that an excessive number of such publications may negatively influence the impact factor of the journal. In the literature of scientometrics, case studies (at least the presence of the term "case study" in the titles of the papers) have a moderate share, but their citation rate is practically equal to that of other publication types.

Small traveling clusters in attractive and repulsive Hamiltonian mean-field models.

PubMed

Barré, Julien; Yamaguchi, Yoshiyuki Y

2009-03-01

Long-lasting small traveling clusters are studied in the Hamiltonian mean-field model by comparing between attractive and repulsive interactions. Nonlinear Landau damping theory predicts that a Gaussian momentum distribution on a spatially homogeneous background permits the existence of traveling clusters in the repulsive case, as in plasma systems, but not in the attractive case. Nevertheless, extending the analysis to a two-parameter family of momentum distributions of Fermi-Dirac type, we theoretically predict the existence of traveling clusters in the attractive case; these findings are confirmed by direct N -body numerical simulations. The parameter region with the traveling clusters is much reduced in the attractive case with respect to the repulsive case.

Verification of NWP Cloud Properties using A-Train Satellite Observations

NASA Astrophysics Data System (ADS)

Kucera, P. A.; Weeks, C.; Wolff, C.; Bullock, R.; Brown, B.

2011-12-01

Recently, the NCAR Model Evaluation Tools (MET) has been enhanced to incorporate satellite observations for the verification of Numerical Weather Prediction (NWP) cloud products. We have developed tools that match fields spatially (both in the vertical and horizontal dimensions) to compare NWP products with satellite observations. These matched fields provide diagnostic evaluation of cloud macro attributes such as vertical distribution of clouds, cloud top height, and the spatial and seasonal distribution of cloud fields. For this research study, we have focused on using CloudSat, CALIPSO, and MODIS observations to evaluate cloud fields for a variety of NWP fields and derived products. We have selected cases ranging from large, mid-latitude synoptic systems to well-organized tropical cyclones. For each case, we matched the observed cloud field with gridded model and/or derived product fields. CloudSat and CALIPSO observations and model fields were matched and compared in the vertical along the orbit track. MODIS data and model fields were matched and compared in the horizontal. We then use MET to compute the verification statistics to quantify the performance of the models in representing the cloud fields. In this presentation we will give a summary of our comparison and show verification results for both synoptic and tropical cyclone cases.

Linear Quadratic Mean Field Type Control and Mean Field Games with Common Noise, with Application to Production of an Exhaustible Resource

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

Graber, P. Jameson, E-mail: jameson-graber@baylor.edu

We study a general linear quadratic mean field type control problem and connect it to mean field games of a similar type. The solution is given both in terms of a forward/backward system of stochastic differential equations and by a pair of Riccati equations. In certain cases, the solution to the mean field type control is also the equilibrium strategy for a class of mean field games. We use this fact to study an economic model of production of exhaustible resources.

Information Technology and the Training and Career Development of Women: The Case of India. Training Discussion Paper No. 30.

ERIC Educational Resources Information Center

Saldanha, Lynette

Information technology (IT) is a growing field in India, with many present and future job opportunities. The field offers expanding opportunities for women, especially in the services sector. Case studies of nine companies that employ a fair number of women in IT showed that, in general, women had equal opportunities with men, especially in…

Assessment of exposure to EMF in a Danish case-control study of childhood cancer.

PubMed

Jensen, J K; Olsen, J H; Folkersen, E

1994-01-01

In Denmark it is permitted to draw overhead lines across residential areas. In connection with a Danish case-control study we developed a method for estimating the historical values of magnetic fields at residences. The study included 1,707 cases with childhood cancer and 4,788 matched population controls. A total of 16,082 different addresses had been occupied by the families from the time of conception until the date of diagnosis. The values of the extreme, maximum, middle and minimum 50 Hz magnetic field strengths originating from a 50-400 kV high-voltage installation were estimated for each of the dwellings included in a potential exposure area. 30 children were exposed to an average level of magnetic fields of 0.1 microT or more. The evaluated Danish method of exposure assessment was compared with the method for residential wiring codes developed by Wertheimer and Leeper /1/. We concluded that the US wiring codes are inappropriate for use in connection with the Danish electricity transmission system.

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

Yang, Jing; Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha, Hunan 410081; Yu, Hongwei, E-mail: hwyu@hunnu.edu.cn

We study the spontaneous excitation of a detector (modeled by a two-level atom) in circular motion coupled nonlinearly to vacuum massless Rarita–Schwinger fields in the ultrarelativistic limit and demonstrate that the spontaneous excitation occurs for ground-state atoms in circular motion in vacuum but the excitation rate is not of a pure thermal form as that of the atoms in linear uniform acceleration. An interesting feature is that terms of odd powers in acceleration appear in the excitation rate whereas in the linear acceleration case there are only terms of even powers present. On the other hand, what makes the presentmore » case unique in comparison to the atom’s coupling to other fields that are previously studied is the appearance of the terms proportional to the seventh and ninth powers of acceleration in the mean rate of change of atomic energy which are absent in the scalar, electromagnetic and Dirac field cases. -- Highlights: •Circular Unruh effect for detector coupled to Rarita–Schwinger field. •Nonlinear coupling between the detector and the fields. •Detector in circular motion does not feel pure thermal bath. •Excitation rate contains terms of odd powers in acceleration.« less

An internet-based epidemiological investigation of the outbreak of H7N9 Avian influenza A in China since early 2013.

PubMed

Mao, Chen; Wu, Xin-Yin; Fu, Xiao-Hong; Di, Meng-Yang; Yu, Yuan-Yuan; Yuan, Jin-Qiu; Yang, Zu-Yao; Tang, Jin-Ling

2014-09-25

In early 2013, a new type of avian influenza, H7N9, emerged in China. It quickly became an issue of great public concern and a widely discussed topic on the Internet. A considerable volume of relevant information was made publicly available on the Internet through various sources. This study aimed to describe the outbreak of H7N9 in China based on data openly available on the Internet and to validate our investigation by comparing our findings with a well-conducted conventional field epidemiologic study. We searched publicly accessible Internet data on the H7N9 outbreak primarily from government and major mass media websites in China up to February 10, 2014. Two researchers independently extracted, compared, and confirmed the information of each confirmed H7N9 case using a self-designed data extraction form. We summarized the epidemiological and clinical characteristics of confirmed H7N9 cases and compared them with those from the field study. According to our data updated until February 10, 2014, 334 confirmed H7N9 cases were identified. The median age was 58 years and 67.0% (219/327) were males. Cases were reported in 15 regions in China. Five family clusters were found. Of the 16.8% (56/334) of the cases with relevant data, 69.6% (39/56) reported a history of exposure to animals. Of the 1751 persons with a close contact with a confirmed case, 0.6% (11/1751) of them developed respiratory symptoms during the 7-day surveillance period. In the 97.9% (327/334) of the cases with relevant data, 21.7% (71/327) died, 20.8% (68/327) were discharged from a hospital, and 57.5% (188/327) were of uncertain status. We compared our findings before February 10, 2014 and those before December 1, 2013 with those from the conventional field study, which had the latter cutoff date of ours in data collection. Our study showed most epidemiological and clinical characteristics were similar to those in the field study, except for case fatality (71/327, 21.7% for our data before February 10; 45/138, 32.6% for our data before December 1; 47/139, 33.8% for the field study), time from illness onset to first medical care (4 days, 3 days, and 1 day), and time from illness onset to death (16.5 days, 17 days, and 21 days). Findings from our Internet-based investigation were similar to those from the conventional field study in most epidemiological and clinical aspects of the outbreak. Importantly, publicly available Internet data are open to any interested researchers and can thus greatly facilitate the investigation and control of such outbreaks. With improved efforts for Internet data provision, Internet-based investigation has a great potential to become a quick, economical, novel approach to investigating sudden issues of great public concern that involve a relatively small number of cases like this H7N9 outbreak.

Building Collaborative Research Opportunities into Study Abroad Programs: A Case Study from Panama

ERIC Educational Resources Information Center

Solís, Patricia; Price, Marie; Adames de Newbill, María

2015-01-01

As universities increase their international study opportunities, enormous potential exists to create geography field courses that provide undergraduates and graduate students with primary research experience and intercultural collaboration. This paper draws from our experience leading a two-week collaborative field course in Panama. We outline…

Understanding the Role of Critical Incidents in Relation to Self-Efficacy during Course-Embedded Preservice Teacher Field Experiences: A Qualitative Study

ERIC Educational Resources Information Center

Epperly, Anna C.

2017-01-01

This qualitative, collective case study documented the development of the self-efficacy beliefs of special education preservice candidates during one semester of a course-embedded field experience in a small, private, faith-based university in the Midwest. Interviews of candidates regarding critical incidents in field experiences as documented by…

Seminary Formation: A Case Study from the Pontifical Beda College, Rome

ERIC Educational Resources Information Center

Strange, Roderick

2015-01-01

This case study account reviews issues related to seminary formation and education at the Beda College, Rome, including Fundamentals of Formation, Community Life, Organizing Formation, Intellectual Formation, Spiritual Formation, Pastoral Formation, and the challenges arising in these fields.

Learning through Cases: Adopting a Nested Approach to Case-Study Work in the Gold Fields Participatory Course Initiative

ERIC Educational Resources Information Center

Lotz-Sisitka, Heila; Raven, Glenda

2004-01-01

This paper argues that there is a need, in southern Africa, to develop in-depth understanding in educational reform initiatives. Through ongoing reflexive development of a professional development programme in environmental education, we have found that case-study methodology, which emphasizes context-dependent knowledge, is significant for…

Implementing Case Studies in Language Teacher Education and Professional Development

ERIC Educational Resources Information Center

Kelch, Kenneth; Malupa-Kim, Miralynn

2014-01-01

Case studies are often traditionally thought of as being used in medical, legal, and business training. Physicians have long been trained by the case method, as medical school students are presented with the particulars of a patient's medical problem and are tasked with providing a diagnosis and course of treatment. In the legal field, Stanford…

Students' Perceptions of a Highly Controversial yet Keystone Species, the Black-Tailed Prairie Dog: A Case Study

ERIC Educational Resources Information Center

Fox-Parrish, Lynne; Jurin, Richard R.

2008-01-01

The authors used a case-study methodology to explore the perceptions of 30 9th-grade biology students relative to black-tailed prairie dogs. The case study, which involved classroom- and field-based experiences that focused on black-tailed prairie dogs, revealed 3 major themes: apathy, egocentrism, and naive conceptions. The authors had hoped that…

Violent Crime in Post-Civil War Guatemala: Causes and Policy Implications

DTIC Science & Technology

2015-03-01

on field research and case studies in Honduras, Bolivia, and Argentina. Bailey’s Security Trap theory is comprehensive in nature and derived from... research question. The second phase uses empirical data and comparative case studies to validate or challenge selected arguments that potentially...Contextual relevancy, historical inference, Tools: Empirics and case conclusions empirical data studies Figme2. Sample Research Methodology E

Current densities in a pregnant woman model induced by simultaneous ELF electric and magnetic field exposure

NASA Astrophysics Data System (ADS)

Cech, R.; Leitgeb, N.; Pediaditis, M.

2008-01-01

The pregnant woman model SILVY was studied to ascertain to what extent the electric current densities induced by 50 Hz homogeneous electric and magnetic fields increase in the case of simultaneous exposure. By vectorial addition of the electric current densities, it could be shown that under worst case conditions the basic restrictions recommended by ICNIRP (International Commission on Non-Ionizing Radiation Protection) guidelines are exceeded within the central nervous system (CNS) of the mother, whereas in sole field exposure they are not. However, within the foetus the induced current densities do not comply with basic restrictions, either from single reference-level electric fields or from simultaneous exposure to electric and magnetic fields. Basic limits were considerably exceeded.

Parametric instabilities of rotor-support systems with application to industrial ventilators

NASA Technical Reports Server (NTRS)

Parszewski, Z.; Krodkiemski, T.; Marynowski, K.

1980-01-01

Rotor support systems interaction with parametric excitation is considered for both unequal principal shaft stiffness (generators) and offset disc rotors (ventilators). Instability regions and types of instability are computed in the first case, and parametric resonances in the second case. Computed and experimental results are compared for laboratory machine models. A field case study of parametric vibrations in industrial ventilators is reported. Computed parametric resonances are confirmed in field measurements, and some industrial failures are explained. Also the dynamic influence and gyroscopic effect of supporting structures are shown and computed.

How to include the variability of TMS responses in simulations: a speech mapping case study

NASA Astrophysics Data System (ADS)

De Geeter, N.; Lioumis, P.; Laakso, A.; Crevecoeur, G.; Dupré, L.

2016-11-01

When delivered over a specific cortical site, TMS can temporarily disrupt the ongoing process in that area. This allows mapping of speech-related areas for preoperative evaluation purposes. We numerically explore the observed variability of TMS responses during a speech mapping experiment performed with a neuronavigation system. We selected four cases with very small perturbations in coil position and orientation. In one case (E) a naming error occurred, while in the other cases (NEA, B, C) the subject appointed the images as smoothly as without TMS. A realistic anisotropic head model was constructed of the subject from T1-weighted and diffusion-weighted MRI. The induced electric field distributions were computed, associated to the coil parameters retrieved from the neuronavigation system. Finally, the membrane potentials along relevant white matter fibre tracts, extracted from DTI-based tractography, were computed using a compartmental cable equation. While only minor differences could be noticed between the induced electric field distributions of the four cases, computing the corresponding membrane potentials revealed different subsets of tracts were activated. A single tract was activated for all coil positions. Another tract was only triggered for case E. NEA induced action potentials in 13 tracts, while NEB stimulated 11 tracts and NEC one. The calculated results are certainly sensitive to the coil specifications, demonstrating the observed variability in this study. However, even though a tract connecting Broca’s with Wernicke’s area is only triggered for the error case, further research is needed on other study cases and on refining the neural model with synapses and network connections. Case- and subject-specific modelling that includes both electromagnetic fields and neuronal activity enables demonstration of the variability in TMS experiments and can capture the interaction with complex neural networks.

Precision bounds for gradient magnetometry with atomic ensembles

NASA Astrophysics Data System (ADS)

Apellaniz, Iagoba; Urizar-Lanz, Iñigo; Zimborás, Zoltán; Hyllus, Philipp; Tóth, Géza

2018-05-01

We study gradient magnetometry with an ensemble of atoms with arbitrary spin. We calculate precision bounds for estimating the gradient of the magnetic field based on the quantum Fisher information. For quantum states that are invariant under homogeneous magnetic fields, we need to measure a single observable to estimate the gradient. On the other hand, for states that are sensitive to homogeneous fields, a simultaneous measurement is needed, as the homogeneous field must also be estimated. We prove that for the cases studied in this paper, such a measurement is feasible. We present a method to calculate precision bounds for gradient estimation with a chain of atoms or with two spatially separated atomic ensembles. We also consider a single atomic ensemble with an arbitrary density profile, where the atoms cannot be addressed individually, and which is a very relevant case for experiments. Our model can take into account even correlations between particle positions. While in most of the discussion we consider an ensemble of localized particles that are classical with respect to their spatial degree of freedom, we also discuss the case of gradient metrology with a single Bose-Einstein condensate.

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…

Nature's Classroom: An Ethnographic Case Study of Environmental Education

ERIC Educational Resources Information Center

Owens, Dorothea Jody

2012-01-01

This ethnographic case study examines the dynamic relationship between culture and environmental education within the context of a specific Florida-based public education program. The School District of Hillsborough County (SDHC) offers the program through a three-day field trip to the study site, Nature's Classroom, and accompanying classroom…

An approach to developing nutrient criteria for Pacific Northwest Estuaries: A case study

EPA Science Inventory

This presentation provides an overview of an approach to developing nutrient criteria for Pacific Northwest (PNW) estuaries, based on a case study of Yaquina Estuary, Oregon. The approach is based on a synthesis of research from field studies, analyses of historical trends in wat...

Sustainability in Housing: A Curriculum Case Study.

ERIC Educational Resources Information Center

Parrott, Kathleen; Emmel, Joann M.

2001-01-01

Explores the influence of environmental issues on the field of housing, from the perspective of sustainable housing. Presents a case study of the development of a college course to address these issues by integrating energy management, air quality, water quality, and waste management. (Author)

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

Negus-De Wys, J.; Dixon, J. M.; Evans, M. A.

This document consists of the following papers: inorganic geochemistry studies of the Eastern Kentucky Gas Field; lithology studies of upper Devonian well cuttings in the Eastern Kentucky Gas Field; possible effects of plate tectonics on the Appalachian Devonian black shale production in eastern Kentucky; preliminary depositional model for upper Devonian Huron age organic black shale in the Eastern Kentucky Gas Field; the anatomy of a large Devonian black shale gas field; the Cottageville (Mount Alto) Gas Field, Jackson County, West Virginia: a case study of Devonian shale gas production; the Eastern Kentucky Gas Field: a geological study of the relationshipsmore » of Ohio Shale gas occurrences to structure, stratigraphy, lithology, and inorganic geochemical parameters; and a statistical analysis of geochemical data for the Eastern Kentucky Gas Field.« less

Use of ``virtual'' field trips in teaching introductory geology

NASA Astrophysics Data System (ADS)

Hurst, Stephen D.

1998-08-01

We designed a series of case studies for Introductory Geology Laboratory courses using computer visualization techniques integrated with traditional laboratory materials. These consist of a comprehensive case study which requires three two-hour long laboratory periods to complete, and several shorter case studies requiring one or two, two-hour laboratory periods. Currently we have prototypes of the Yellowstone National Park, Hawaii volcanoes and the Mid-Atlantic Ridge case studies. The Yellowstone prototype can be used to learn about a wide variety of rocks and minerals, about geothermal activity and hydrology, about volcanic hazards and the hot-spot theory of plate tectonics. The Hawaiian exercise goes into more depth about volcanoes, volcanic rocks and their relationship to plate movements. The Mid-Atlantic Ridge project focuses on formation of new ocean crust and mineral-rich hydrothermal deposits at spreading centers. With new improvements in visualization technology that are making their way to personal computers, we are now closer to the ideal of a "virtual" field trip. We are currently making scenes of field areas in Hawaii and Yellowstone which allow the student to pan around the area and zoom in on interesting objects. Specific rocks in the scene will be able to be "picked up" and studied in three dimensions. This technology improves the ability of the computer to present a realistic simulation of the field area and allows the student to have more control over the presentation. This advanced interactive technology is intuitive to control, relatively cheap and easy to add to existing computer programs and documents.

Center for the Built Environment: Research on Building Envelope Systems

Science.gov Websites

Studies Facade and Perimeter Zone Field Study Facades and Thermal Comfort Facade Symposium Mixed-Mode Research Adaptive Comfort Model Mixed-Mode Case Studies Operable Windows and Thermal Comfort Occupant thermal preferences in naturally ventilated as sealed buildings? Case Study Research of Mixed-Mode Office

First do no harm: is it any longer safe to write case reports?

PubMed

Brown, Laura S

2014-12-01

This article explores the risks to authors and their clients of creating psychological literature based on case studies. The author considers how the events that occurred in Nicole Taus's case might have affected those clients with whom she wrote case studies. Finally, the author analyzes the potential losses to the field should other participants in case studies be at risk of the kind of intrusive invasion of privacy experienced by Taus and calls for the development of ethical principles for psychological science. © The Author(s) 2014.

3D magneto-convective heat transfer in CNT-nanofluid filled cavity under partially active magnetic field

NASA Astrophysics Data System (ADS)

Al-Rashed, Abdullah A. A. A.; Kolsi, Lioua; Oztop, Hakan F.; Aydi, Abdelkarim; Malekshah, Emad Hasani; Abu-Hamdeh, Nidal; Borjini, Mohamed Naceur

2018-05-01

A computational study has been performed to investigate the effects of partially active magnetic field on natural convection heat transfer in CNT-nanofluid filled and three-dimensional differentially heated closed space. Two cases are considered to see this effect as magnetic field is applied to upper half (Case I) and lower half (Case II) while remaining walls are insulated. The finite volume method is used to solve governing equations and results are obtained for different governing parameters as Hartmann number (0 ≤ Ha ≤ 100), nanoparticle volume fraction (0 ≤ φ ≤ 0.05) and height of the active zone (0 ≤ LB ≤ 1). It is found that location of magnetic field plays an important role even at the same Hartmann number. Thus, it can be a good parameter to control heat and fluid flow inside the closed space.

Single-Case Design Research: Building the Evidence-Base in the Field of Education of Deaf and Hard of Hearing Students

ERIC Educational Resources Information Center

Cannon, Joanna E.; Guardino, Caroline; Antia, Shirin D.; Luckner, John L.

2015-01-01

The field of education of deaf and hard of hearing (DHH) students has a paucity of evidence-based practices (EBPs) to guide instruction. The authors discussed how the research methodology of single-case design (SCD) can be used to build EBPs through direct and systematic replication of studies. An overview of SCD research methods is presented,…

[Clinical efficacy of flomoxef in the field of pediatrics].

PubMed

Ogura, H; Kubota, H; Murakami, N; Tomoda, T; Hamada, F; Matsumoto, K; Araki, K; Ogura, Y; Kurashige, T; Kitamura, I

1987-08-01

A new oxacephem antibiotic, flomoxef sodium (FMOX, 6315-S), was studied for its clinical efficacy in the field of pediatrics. The treated patients were infants and children ranging from 6 months to 14 years old suffering from bacterial pneumonia in 3 cases, acute tonsillitis in 2 cases, acute enterocolitis in 2 cases, and cellulitis and urinary tract infection in 1 case each, a total of 9 cases. FMOX was administered at (levels of) 57-150 mg/kg in daily dose with durations of treatment ranging from 5 to 18 days. Clinical efficacies of good or excellent results were obtained in all cases (excellent in 4, good in 5). As an adverse reaction, eosinophilia was observed in 1 patient. This elevation is, however, normalized with the cessation of the treatment.

The School for Field Studies Centre for Coastal Studies: A Case Study of Sustainable Development Education in Mexico

ERIC Educational Resources Information Center

Farrell, T. A.; Ollervides, F.

2005-01-01

Purpose: To present the School for Field Studies-Centre for Coastal Studies (SFS-CCS) study abroad Mexico program, and consider its relative success as a sustainable development education program. Design/methodology/approach: The SFS-CCS academic model and results of its implementation are presented. Program success is discussed by applying…

Determining Student Competency in Field Placements: An Emerging Theoretical Model

ERIC Educational Resources Information Center

Salm, Twyla L.; Johner, Randy; Luhanga, Florence

2016-01-01

This paper describes a qualitative case study that explores how twenty-three field advisors, representing three human service professions including education, nursing, and social work, experience the process of assessment with students who are struggling to meet minimum competencies in field placements. Five themes emerged from the analysis of…

Walking the Talk: Towards a More Inclusive Field of Disability Studies

ERIC Educational Resources Information Center

Opini, Bathseba

2016-01-01

This paper is a conversation about growing an inclusive field of disability studies. The paper draws on data collected through an analysis of existing disability studies programmes in selected Canadian universities. The paper makes a case for including diverse perspectives, experiences, viewpoints, and voices in these programmes. In this work, I…

Environmental Learning Using a Problem-Based Approach in the Field: A Case Study of a Hong Kong School

ERIC Educational Resources Information Center

Kwan, Tammy; So, Max

2008-01-01

This study investigated the environmental learning of a group of senior geography students through a problem-based learning (PBL) field programme to see if the goals of education "for" the environment could be accomplished. In the PBL field programme, the students were given a problem statement concerning a real-life scenario of an old…

The Radical Reforms: A Historic Shift in the National Council for the Social Studies

ERIC Educational Resources Information Center

Binford, Paul E.

2013-01-01

The National Council for the Social Studies (NCSS or Council), founded in 1921, is the premiere professional association in the social studies field. This treatment of a transformative period in the institutional history of the Council is intended to serve as a partial antidote to the social studies field's longstanding case of "historical…

Pore Pressure and Field stress variation from Salt Water Injection; A case Study from Beaver Lodge Field in Williston Basin

NASA Astrophysics Data System (ADS)

Mohammed, R. A.; Khatibi, S.

2017-12-01

One of the major concerns in producing from oil and gas reservoirs in North American Basins is the disposal of high salinity salt water. It is a misconception that Hydro frack triggers Earthquakes, but due to the high salinity and density of water being pumped to the formation that has pore space of the rock already filled, which is not the case in Hydro-frack or Enhanced Oil Recovery in which fracturing fluid is pumped into empty pore space of rocks in depleted reservoirs. A review on the Bakken history showed that the concerns related to induce seismicity has increased over time due to variations in Pore pressure and In-situ stress that have shown steep changes in the region over the time. In this study, we focused on Pore pressure and field Stress variations in lower Cretaceous Inyan Kara and Mississippian Devonian Bakken, Inyan Kara is the major source for class-II salt-water disposal in the basin. Salt-water disposal is the major cause for induced seismicity. A full field study was done on Beaver Lodge Field, which has many salt-water disposal wells Adjacent to Oil and Gas Wells. We analyzed formation properties, stresses, pore-pressure, and fracture gradient profile in the field and. The constructed Mechanical Earth Model (MEM) revealed changes in pore pressure and stresses over time due to saltwater injection. Well drilled in the past were compared to recently drilled wells, which showed much stress variations. Safe mud weight Window of wells near proximity of injection wells was examined which showed many cases of wellbore instabilities. Results of this study will have tremendous impact in studying environmental issues and the future drilling and Fracking operations.

3-D Hybrid Kinetic Modeling of the Interaction Between the Solar Wind and Lunar-like Exospheric Pickup Ions in Case of Oblique/ Quasi-Parallel/Parallel Upstream Magnetic Field

NASA Technical Reports Server (NTRS)

Lipatov, A. S.; Farrell, W. M.; Cooper, J. F.; Sittler, E. C., Jr.; Hartle, R. E.

2015-01-01

The interactions between the solar wind and Moon-sized objects are determined by a set of the solar wind parameters and plasma environment of the space objects. The orientation of upstream magnetic field is one of the key factors which determines the formation and structure of bow shock wave/Mach cone or Alfven wing near the obstacle. The study of effects of the direction of the upstream magnetic field on lunar-like plasma environment is the main subject of our investigation in this paper. Photoionization, electron-impact ionization and charge exchange are included in our hybrid model. The computational model includes the self-consistent dynamics of the light (hydrogen (+), helium (+)) and heavy (sodium (+)) pickup ions. The lunar interior is considered as a weakly conducting body. Our previous 2013 lunar work, as reported in this journal, found formation of a triple structure of the Mach cone near the Moon in the case of perpendicular upstream magnetic field. Further advances in modeling now reveal the presence of strong wave activity in the upstream solar wind and plasma wake in the cases of quasiparallel and parallel upstream magnetic fields. However, little wave activity is found for the opposite case with a perpendicular upstream magnetic field. The modeling does not show a formation of the Mach cone in the case of theta(Sub B,U) approximately equal to 0 degrees.

A Case Study of Information Resource Management in the Department of Defense

DTIC Science & Technology

1992-03-01

prepared to make effective decisions in a military environment. The justification for the use of information technology (IT) in support of operations...t ement No PfICt NO [ask No r 11 TITLE (Include Security Classification) A Case Study ofinformation Resourcc Management in the Departnentufl)clelse...block number) FIELD GROUP SUBGROUP Case study,Corporate Information Management, CIM. Information Hesource Munagenitnt IRM 19 ABSTRACT (continue on

An outbreak of vancomycin-resistant Enterococcus faecium in an acute care pediatric hospital: Lessons from environmental screening and a case-control study

PubMed Central

Drews, Steven J; Richardson, Susan E; Wray, Rick; Freeman, Renee; Goldman, Carol; Streitenberger, Laurie; Stevens, Derek; Goia, Cristina; Kovach, Danuta; Brophy, Jason; Matlow, Anne G

2008-01-01

BACKGROUND The present study describes a vancomycin-resistant enterococci (VRE) outbreak investigation and a case-control study to identify risk factors for VRE acquisition in a tertiary care pediatric hospital. OBJECTIVE To report an outbreak investigation and a case-control study to identify risk factors for VRE colonization or infection in hospitalized children. METHODS Screening for VRE cases was performed by culture or polymerase chain reaction. A case-control study of VRE-colonized patients was undertaken. Environmental screening was performed using standard culture and susceptibility methods, with pulsed-field gel electrophoresis to determine relationships between VRE isolates. Statistical analysis was performed using SAS version 9.0 (SAS Institute Inc, USA). RESULTS Thirty-four VRE-positive cases were identified on 10 wards between February 28, 2005, and May 27, 2005. Pulsed-field gel electrophoresis analysis confirmed a single outbreak strain that was also isolated from a video game found on one affected ward. Multivariate analysis identified cephalosporin use as the major risk factor for VRE colonization. CONCLUSIONS In the present study outbreak, VRE colonization was significantly associated with cephalosporin use. Because shared recreational items and environmental surfaces may be colonized by VRE, they warrant particular attention in housekeeping protocols, particularly in pediatric institutions. PMID:19412380

Gauge Field Localization on Deformed Branes

NASA Astrophysics Data System (ADS)

Tofighi, A.; Moazzen, M.; Farokhtabar, A.

2016-02-01

In this paper, we utilise the Chumbes-Holf da Silva-Hott (CHH) mechanism to investigate the issue of gauge field localization on a deformed brane constructed with one scalar field, which can be coupled to gravity minimally or non-minimally. The study of deformed defects is important because they contain internal structures which may have implications in braneworld models. With the CHH mechanism, we find that the massless zero mode of gauge field, in the case of minimal or non-minimal coupling is localized on the brane. Moreover, in the case of non-minimal coupling, it is shown that, when the non-minimal coupling constant is larger than its critical value, then the zero mode is localized on each sub brane.

Psychology and Gender.

ERIC Educational Resources Information Center

Henley, Nancy M.

1985-01-01

Considers recent efforts within the field of psychology to understand issues involving gender. Demonstrates patterns of development within feminist psychology and its relation to mainstream psychology. Examines status of the field, two case studies, and new research. (Author/SA)

Taking Them into the Field: Mathematics Teacher Candidate Learning about Equity-Oriented Teaching Practices in a Mediated Field Experience

ERIC Educational Resources Information Center

Campbell, Sara Sunshine

2012-01-01

Teacher education programs have been criticized as too theoretical with university courses disconnected from the practical realities of classrooms. This single case study investigates a model of teacher education that worked to bridge the coursework-fieldwork gap in teacher education. The Mediated Field Experience (MFE) is a field experience…

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…

Mode 2 and the Tension between Excellence and Utility: The Case of a Policy-Relevant Research Field in Sweden

ERIC Educational Resources Information Center

Håkansta, Carin; Jacob, Merle

2016-01-01

This paper investigates the impact of changing science policy doctrines on the development of an academic field, working life research. Working life research is an interdisciplinary field of study in which researchers and stakeholders collaborated to produce relevant knowledge. The development of the field, we argue, was both facilitated and…

Hepatic alveolar echinococcosis: correlative US and CT study

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

Didier, D.; Weiler, S.; Rohmer, P.

1985-01-01

A total of 24 cases of hepatic alveolar echinococcosis (HAE) due to Echinococcus multilocularis was assessed by US and CT. The diagnosis was confirmed in all cases by immunologic and histologic study. Both US and CT patterns of HAE showed changes of liver morphology in both contour and size. Abnormal areas of parenchyma were nodular or in fields, irregular, heterogeneous, and basically echogenic. Clustered microcalcifications were encountered within the abnormal parenchymal fields in 50% of cases, and necrotized zones occurred in 40% of cases. Dilatation of intrahepatic bile ducts was commonly seen, especially on US; hilar involvement was frequent. Follow-upmore » by both techniques can display increases of primary lesions, occurrence of new foci, and local or regional extensions. Precise evaluations of the lesions arising from correlative use of US and CT permits adequate therapeutic management.« less

Myocardial infarction increases progressive visual field defects in well treated early primary open angle glaucoma--a prospective case control study.

PubMed

Mondal, Lakshmikanta; Baidya, Krishnapada; Choudhury, Himadri; Roy, Rupam

2013-06-01

The purpose of the study was to evaluate the progression of glaucomatous field damage in patients with stable primary open angle glaucoma after an attack of myocardial infarction. In this case control study, 62 open angle glaucoma patients were selected and regularly followed up. Among 62 patients, 9 had an attack of myocardial infarction. The intra-ocular pressure and visual field progression of both the groups (myocardial infarction versus no myocardial infarction) were analysed. Three (33.3%) out of 9 patients who had suffered from myocardial infarction showed progressive visual field loss whereas only 9 (16.9%) out of 53 patients who did not suffer from myocardial infarction, showed progressive field changes. Both the groups had stable target intra-ocular pressure between 14 and 16 mm Hg. Myocardial infarction may adversely influence the progression of primary open angle glaucoma which is suspected to result from ischaemia induced neuronal loss and only control of intraocular pressure is not the only solution. We have to look for other drugs that prevents ischaemia induced neuronal damage.

Incidental Becomes Visible: A Comparison of School- and Community-Based Field Experience Narratives

ERIC Educational Resources Information Center

Holder, K. C.; Downey, Jayne A.

2008-01-01

The purpose of this study was to describe and compare student learning documented using written field experience summary narratives and occurring in community-based or school-based locations. Utilizing a hybrid portraiture--instrumental case study design, two researchers selected participants from undergraduate educational psychology courses using…

Providing Culturally Responsive Teaching in Field-Based and Student Teaching Experiences: A Case Study

ERIC Educational Resources Information Center

Kea, Cathy D.; Trent, Stanley C.

2013-01-01

This mixed design study chronicles the yearlong outcomes of 27 undergraduate preservice teacher candidates' ability to design and deliver culturally responsive lesson plans during field-based experience lesson observations and student teaching settings after receiving instruction in a special education methods course. While components of…

Evaluation of experimental installation of fly ash concrete in Louisa : Concrete case study number 32.

DOT National Transportation Integrated Search

1979-01-01

The objective of this study was to investigate the resistance of field concretes containing fly ash to damage from cycles of freezing and thawing as evidenced by scaling, based upon a reevaluation of a field project. In 1955 and 1956 an experimental ...

Ethical Considerations in Filing Personal Bankruptcy: A Hypothetical Case Study

ERIC Educational Resources Information Center

Landry, Robert J., III

2012-01-01

A great deal of research by legal studies scholars pertains to employment law, international law, and corporate governance, as well as other fields including ethics and international law. The fields typically addressed are very important and rightfully receive considerable attention in the scholarship and textbooks. However, bankruptcy as a…

Electrochemical processes and mechanistic aspects of field-effect sensors for biomolecules

PubMed Central

Huang, Weiguo; Diallo, Abdou Karim; Dailey, Jennifer L.; Besar, Kalpana

2017-01-01

Electronic biosensing is a leading technology for determining concentrations of biomolecules. In some cases, the presence of an analyte molecule induces a measured change in current flow, while in other cases, a new potential difference is established. In the particular case of a field effect biosensor, the potential difference is monitored as a change in conductance elsewhere in the device, such as across a film of an underlying semiconductor. Often, the mechanisms that lead to these responses are not specifically determined. Because improved understanding of these mechanisms will lead to improved performance, it is important to highlight those studies where various mechanistic possibilities are investigated. This review explores a range of possible mechanistic contributions to field-effect biosensor signals. First, we define the field-effect biosensor and the chemical interactions that lead to the field effect, followed by a section on theoretical and mechanistic background. We then discuss materials used in field-effect biosensors and approaches to improving signals from field-effect biosensors. We specifically cover the biomolecule interactions that produce local electric fields, structures and processes at interfaces between bioanalyte solutions and electronic materials, semiconductors used in biochemical sensors, dielectric layers used in top-gated sensors, and mechanisms for converting the surface voltage change to higher signal/noise outputs in circuits. PMID:29238595

Determining Crack Tip Field Parameters for Elastic-Plastic Materials via an Estimation Scheme

DTIC Science & Technology

1981-07-01

of the Materials Laboratory was the Project Monitor for this study of the application of the Nonlinear Fracture Mechanics (NLFM) parameters to the...fracture mechanics (LEFM) is applicable . If the plastic zone size is large, compared to the case of small scale yielding, LEFM is not applicable . The...above HRR field equations are applicable only for the case of stationary cracks. 2.2 PARAMETER DETERMINATION For elastic-plastic materials, the

Microwave absorption studies on high-T sub c superconductors and related materials II; Electron spin resonance of DPPH coated on Y sub 1 Ba sub 2 Cu sub 3 O sub y as a probe of magnetic field variations

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

Sugawara, K.; Baar, D.J.; Shiohara, Y.

1991-05-10

This paper reports on the ESR linewidth ({Delta}{ital H}{sub p{bar p}}) of DPPH coated on the surface of powder specimens of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub y} studied under various magnetic field and temperature conditions. {Delta}{ital H}{sub p{bar p}} increases substantially with decreasing temperature in the field cooled case, whereas almost no linewidth broadening was found in the zero field cooled case. {Delta}{ital H}{sub p{bar p}} was found to be sensitive to the applied magnetic field. This effect was very pronounced at temperatures lower than 40 K, but decreased strongly with increasing temperature. The broadening of the resonance lineshape has beenmore » attributed to spatial and temporal variations of the fluxon distribution in the powder particles.« less

Fostering Leadership through Organizational Structure

ERIC Educational Resources Information Center

Willett, Brantley P.

2012-01-01

This case study discusses the postindustrial paradigm of leadership and its influence on the field of leadership and also the higher education leadership literature. Furthermore, this case study examines the structure of one university honor society to discuss how the structure allows for the development of multiple leaders within the…

Motor carrier case study evaluation report : appendix C, Vol. 2 : case study field notes, the Crescent Evaluation

DOT National Transportation Integrated Search

1994-02-01

The Crescent Project element of the HELP Program is a bi-national multi-jurisdictional : cooperative research and demonstration initiative involving the public and private sectors in an : application of advanced technologies for the creation of an in...

Casimir force in a Lorentz violating theory

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

Frank, Mariana; Turan, Ismail

2006-08-01

We study the effects of the minimal extension of the standard model including Lorentz violation on the Casimir force between two parallel conducting plates in the vacuum. We provide explicit solutions for the electromagnetic field using scalar field analogy, for both the cases in which the Lorentz violating terms come from the CPT-even or CPT-odd terms. We also calculate the effects of the Lorentz violating terms for a fermion field between two parallel conducting plates and analyze the modifications of the Casimir force due to the modifications of the Dirac equation. In all cases under consideration, the standard formulas formore » the Casimir force are modified by either multiplicative or additive correction factors, the latter case exhibiting different dependence on the distance between the plates.« less

Multiple scattering corrections to the Beer-Lambert law. 2: Detector with a variable field of view.

PubMed

Zardecki, A; Tam, W G

1982-07-01

The multiple scattering corrections to the Beer-Lambert law in the case of a detector with a variable field of view are analyzed. We introduce transmission functions relating the received radiant power to reference power levels relevant to two different experimental situations. In the first case, the transmission function relates the received power to a reference power level appropriate to a nonattenuating medium. In the second case, the reference power level is established by bringing the receiver to the close-up position with respect to the source. To examine the effect of the variation of the detector field of view the behavior of the gain factor is studied. Numerical results modeling the laser beam propagation in fog, cloud, and rain are presented.

Application of remote sensing for prediction and detection of thermal pollution, phase 2

NASA Technical Reports Server (NTRS)

Veziroglu, T. N.; Lee, S. S.

1975-01-01

The development of a predictive mathematical model for thermal pollution in connection with remote sensing measurements was continued. A rigid-lid model has been developed and its application to far-field study has been completed. The velocity and temperature fields have been computed for different atmospheric conditions and for different boundary currents produced by tidal effects. In connection with the theoretical work, six experimental studies of the two sites in question (Biscayne Bay site and Hutchinson Island site) have been carried out. The temperature fields obtained during the tests at the Biscayne Bay site have been compared with the predictions of the rigid-lid model and these results are encouraging. The rigid-lid model is also being applied to near-field study. Preliminary results for a simple case have been obtained and execution of more realistic cases has been initiated. The development of a free-surface model also been initiated. The governing equations have been formulated and the computer programs have been written.

Community-Based Field Experiences in Teacher Education: Possibilities for a Pedagogical Third Space

ERIC Educational Resources Information Center

Hallman, Heidi L.

2012-01-01

The present article discusses the importance of community-based field experiences as a feature of teacher education programs. Through a qualitative case study, prospective teachers' work with homeless youth in an after-school initiative is presented. Framing community-based field experiences in teacher education through "third space" theory, the…

Communication Processes in the Field Research Interview Setting: A Case Study.

ERIC Educational Resources Information Center

Mason, Susan A.

For those involved in research of any type, the gathering of complete, relevant, and untainted information is the ultimate goal. The collection of valuable information is particularly challenging in the social sciences, which often call for qualitative field research. The effective field research interviewer must not only be knowledgeable of the…

Concurrent Infusion of Integrated Behavioral Health Practice into Social Work Field and Classroom Instruction

ERIC Educational Resources Information Center

Smith-Osborne, Alexa; Daniel, Kathryn

2017-01-01

This administrative case study describes a concurrent infusion of integrated behavioral health (IBH) practice into social work field and classroom instruction using the same manualized IBH treatment as the core treatment content. The infusion was applied to youth/young adult and older adult populations in field instruction and classroom…

An Analysis of Teachers' Concept Confusion Concerning Electric and Magnetic Fields

ERIC Educational Resources Information Center

Hekkenberg, Ans; Lemmer, Miriam; Dekkers, Peter

2015-01-01

In an exploratory study, 36 South African physical science teachers' understanding of basic concepts concerning electric and magnetic fields was studied from a perspective of possible concept confusion. Concept confusion is said to occur when features of one concept are incorrectly attributed to a different concept, in the case of this study to…

Optimal field-splitting algorithm in intensity-modulated radiotherapy: Evaluations using head-and-neck and female pelvic IMRT cases

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

Dou, Xin; Kim, Yusung, E-mail: yusung-kim@uiowa.edu; Bayouth, John E.

2013-04-01

To develop an optimal field-splitting algorithm of minimal complexity and verify the algorithm using head-and-neck (H and N) and female pelvic intensity-modulated radiotherapy (IMRT) cases. An optimal field-splitting algorithm was developed in which a large intensity map (IM) was split into multiple sub-IMs (≥2). The algorithm reduced the total complexity by minimizing the monitor units (MU) delivered and segment number of each sub-IM. The algorithm was verified through comparison studies with the algorithm as used in a commercial treatment planning system. Seven IMRT, H and N, and female pelvic cancer cases (54 IMs) were analyzed by MU, segment numbers, andmore » dose distributions. The optimal field-splitting algorithm was found to reduce both total MU and the total number of segments. We found on average a 7.9 ± 11.8% and 9.6 ± 18.2% reduction in MU and segment numbers for H and N IMRT cases with an 11.9 ± 17.4% and 11.1 ± 13.7% reduction for female pelvic cases. The overall percent (absolute) reduction in the numbers of MU and segments were found to be on average −9.7 ± 14.6% (−15 ± 25 MU) and −10.3 ± 16.3% (−3 ± 5), respectively. In addition, all dose distributions from the optimal field-splitting method showed improved dose distributions. The optimal field-splitting algorithm shows considerable improvements in both total MU and total segment number. The algorithm is expected to be beneficial for the radiotherapy treatment of large-field IMRT.« less

Neutron Star Structure in the Presence of Conformally Coupled Scalar Fields

NASA Technical Reports Server (NTRS)

Sultana, Joseph; Bose, Benjamin; Kazanas, Demosthenes

2014-01-01

Neutron star models are studied in the context of scalar-tensor theories of gravity in the presence of a conformally coupled scalar field, using two different numerical equations of state (EoS) representing different degrees of stiffness. In both cases we obtain a complete solution by matching the interior numerical solution of the coupled Einstein-scalar field hydrostatic equations, with an exact metric on the surface of the star. These are then used to find the effect of the scalar field and its coupling to geometry, on the neutron star structure, particularly the maximum neutron star mass and radius. We show that in the presence of a conformally coupled scalar field, neutron stars are less dense and have smaller masses and radii than their counterparts in the minimally coupled case, and the effect increases with the magnitude of the scalar field at the center of the star.

The Opinions of Masters Students about the Learning Program in the Field of Teaching Turkish to Foreigners

ERIC Educational Resources Information Center

Kilinç, Hasan Huseyin

2015-01-01

The purpose of this study is to determine the opinions of Master students about the learning program in the field of teaching Turkish to foreigners. In the study, case study design which is one of the qualitative research methods was used. The population of the study consists of students studying in the Master program with thesis of Teaching…

Successful AP Music Theory Instruction: A Case Study

ERIC Educational Resources Information Center

Buonviri, Nathan O.

2018-01-01

The purpose of this case study was to examine the instructional approach of a highly successful Advanced Placement Music Theory teacher. I visited the participant's class twice a week for 14 weeks, taking field notes, conducting interviews, and collecting instructional artifacts. Analysis of qualitative data revealed three main themes: classroom…

Student-Authored Case Studies as a Reflective Component of Teacher Education

ERIC Educational Resources Information Center

Rosse-Richards, Kevin Andrews; Hemphill, Michael A.; Wilson, Wesley J.

2015-01-01

Field experiences are often conceptualized as integral to teacher education programming. However, there are often inconsistencies between the beliefs and values espoused in teacher education and those pre-service teachers encounter in schools that they must navigate to be successful. Among other strategies, writing case studies about their…

Professional Identity of an Early Childhood Black Teacher in a Predominantly White School: A Case Study

ERIC Educational Resources Information Center

Al-Khatib, Amal J.; Lash, Martha J.

2017-01-01

This qualitative case study investigated the role of race, school context, and personal and professional experiences in the formation of an early childhood minority teacher's professional identity. Data sources included interviews, observations, conversations, field notes and school artefacts. Member checking, triangulation and extended…

NITRATE CONTAMINATION OF GROUND WATER FROM LAND APPLICATION OF SWINE WASTE: CASE STUDY AND GENERAL CONSIDERATIONS

EPA Science Inventory

Guidelines for land application of CAFO waste may not be sufficient to prevent ground water contamination by nitrate. A case study is presented illustrating the problem for one field site disposing of swine waste. Data are discussed in context with documented land application ...

The Role of Simulation Case Studies in Enterprise Education

ERIC Educational Resources Information Center

Tunstall, Richard; Lynch, Martin

2010-01-01

Purpose: This paper aims to explore the role of electronic simulation case studies in enterprise education, their effectiveness, and their relationship to traditional forms of classroom-based approaches to experiential learning. The paper seeks to build on previous work within the field of enterprise and management education, specifically in…

Learning in the Making: A Comparative Case Study of Three Makerspaces

ERIC Educational Resources Information Center

Sheridan, Kimberly M.; Halverson, Erica Rosenfeld; Litts, Breanne K.; Brahms, Lisa; Jacobs-Priebe, Lynette; Owens, Trevor

2014-01-01

Through a comparative case study, Sheridan and colleagues explore how makerspaces may function as learning environments. Drawing on field observations, interviews, and analysis of artifacts, videos, and other documents, the authors describe features of three makerspaces and how participants learn and develop through complex design and making…

Occupational exposure to magnetic fields in relation to mortality from brain cancer among electricity generation and transmission workers.

PubMed Central

Harrington, J M; McBride, D I; Sorahan, T; Paddle, G M; van Tongeren, M

1997-01-01

OBJECTIVE: To investigate whether the risks of mortality from brain cancer are related to occupational exposure to magnetic fields. METHODS: A total of 112 cases of primary brain cancer (1972-91) were identified from a cohort of 84,018 male and female employees of the (then) Central Electricity Generating Board and its privatised successor companies. Individual cumulative occupational exposures to magnetic fields were estimated by linking available computerised job history data with magnetic field measurements collected over 675 person-workshifts. Estimated exposure histories of the case workers were compared with those of 654 control workers drawn from the cohort (nested case-control study), by means of conditional logistic regression. RESULTS: For exposure assessments based on arithmetic means, the risk of mortality from brain cancer for subjects with an estimated cumulative exposure to magnetic fields of 5.4-13.4 microT.y v subjects with lower exposures (0.0-5.3 microT.y) was 1.04 (95% confidence interval (95% CI) 0.60 to 1.80). The corresponding relative risk in subjects with higher exposures (> or = 13.5 microT.y) was 0.95 (95% CI 0.54 to 1.69). There was no indication of a positive trend for cumulative exposure and risk of mortality from brain cancer either when the analysis used exposure assessments based on geometric means or when the analysis was restricted to exposures received within five years of the case diagnosis (or corresponding period for controls). CONCLUSIONS: Although the exposure categorisation was based solely on recent observations, the study findings do not support the hypothesis that the risk of brain cancer is associated with occupational exposure to magnetic fields. PMID:9072027

A Three-Dimensional Target Depth-Resolution Method with a Single-Vector Sensor

PubMed Central

Zhao, Anbang; Bi, Xuejie; Hui, Juan; Zeng, Caigao; Ma, Lin

2018-01-01

This paper mainly studies and verifies the target number category-resolution method in multi-target cases and the target depth-resolution method of aerial targets. Firstly, target depth resolution is performed by using the sign distribution of the reactive component of the vertical complex acoustic intensity; the target category and the number resolution in multi-target cases is realized with a combination of the bearing-time recording information; and the corresponding simulation verification is carried out. The algorithm proposed in this paper can distinguish between the single-target multi-line spectrum case and the multi-target multi-line spectrum case. This paper presents an improved azimuth-estimation method for multi-target cases, which makes the estimation results more accurate. Using the Monte Carlo simulation, the feasibility of the proposed target number and category-resolution algorithm in multi-target cases is verified. In addition, by studying the field characteristics of the aerial and surface targets, the simulation results verify that there is only amplitude difference between the aerial target field and the surface target field under the same environmental parameters, and an aerial target can be treated as a special case of a surface target; the aerial target category resolution can then be realized based on the sign distribution of the reactive component of the vertical acoustic intensity so as to realize three-dimensional target depth resolution. By processing data from a sea experiment, the feasibility of the proposed aerial target three-dimensional depth-resolution algorithm is verified. PMID:29649173

A Three-Dimensional Target Depth-Resolution Method with a Single-Vector Sensor.

PubMed

Zhao, Anbang; Bi, Xuejie; Hui, Juan; Zeng, Caigao; Ma, Lin

2018-04-12

This paper mainly studies and verifies the target number category-resolution method in multi-target cases and the target depth-resolution method of aerial targets. Firstly, target depth resolution is performed by using the sign distribution of the reactive component of the vertical complex acoustic intensity; the target category and the number resolution in multi-target cases is realized with a combination of the bearing-time recording information; and the corresponding simulation verification is carried out. The algorithm proposed in this paper can distinguish between the single-target multi-line spectrum case and the multi-target multi-line spectrum case. This paper presents an improved azimuth-estimation method for multi-target cases, which makes the estimation results more accurate. Using the Monte Carlo simulation, the feasibility of the proposed target number and category-resolution algorithm in multi-target cases is verified. In addition, by studying the field characteristics of the aerial and surface targets, the simulation results verify that there is only amplitude difference between the aerial target field and the surface target field under the same environmental parameters, and an aerial target can be treated as a special case of a surface target; the aerial target category resolution can then be realized based on the sign distribution of the reactive component of the vertical acoustic intensity so as to realize three-dimensional target depth resolution. By processing data from a sea experiment, the feasibility of the proposed aerial target three-dimensional depth-resolution algorithm is verified.

The sensitivity of aquatic insects to divalent metals: a comparative analysis of laboratory and field data.

PubMed

Brix, Kevin V; DeForest, David K; Adams, William J

2011-09-15

Laboratory studies have traditionally indicated that aquatic insects are relatively insensitive to metals while field studies have suggested them to be among the most sensitive aquatic invertebrate taxa. We reviewed and synthesized available studies in the literature to critically assess why this discrepancy exists. Despite the intense effort to study the effects of metals on aquatic biota over the past several decades, we found studies specific to insects to still be relatively limited. In general, the discrepancy between laboratory and field studies continues with few efforts having been made to elucidate the ecological and physiological mechanisms that underlie the relative sensitivity (or insensitivity) of aquatic insects to metals. However, given the limited data available, it appears that aquatic insects are indeed relatively insensitive to acute metal exposures. In contrast, we suggest that some aquatic insect taxa may be quite sensitive to chronic metal exposure and in some cases may not be protected by existing water quality criteria for metals. The discrepancy between laboratory and field studies with respect to chronic sensitivity appears to largely be driven by the relatively short exposure periods in laboratory studies as compared to field studies. It also appears that, in some cases, the sensitivity of aquatic insects in field studies may be the result of direct effects on primary producers, which lead to indirect effects via the food chain on aquatic insects. Finally, available evidence suggests that diet is an important source of metal accumulation in insects, but to date there have been no conclusive studies evaluating whether dietary metal accumulation causes toxicity. There is a clear need for developing a more mechanistic understanding of aquatic insect sensitivity to metals in long-term laboratory and field studies. Copyright © 2011 Elsevier B.V. All rights reserved.

Relation Between Lightning Activity of Summer and Winter Thunderclouds and Surface Electric Field Variation, Japan

NASA Technical Reports Server (NTRS)

Michimoto, K.; Shimura, T.; Suzuki, T.

1999-01-01

In winter, active convective clouds frequently form along the coastline of the Hokuriku district, in association with strong advection of Siberian air masses over the Sea of Japan. On the other hand, in summer, many thunderclouds form in the Kanto region in the afternoon every day. Summer and winter thunderclouds were investigated by field works, operation of the C- and X-band weather radars and a car-borne fieldmill. The investigation found a very close relation between the temporal variation of 3-dimensional radar echo and surface electric field magnitude detected by a car-borne fieldmill in the case of summer thunderclouds and winter convective clouds or thunderclouds. The study probed the close relation among radar echoes, quantity of thunderclouds and surface electric field magnitude in the summer and winter seasons. We think that summer thundercloud activity can basically be equated with winter thundercloud lightning activity, except that the magnitude of surface electric field under summer thunderclouds in the case of the Kanto region cannot be equated with that under winter thunderclouds in the case of the Hokuriku district in winter.

Compressible Analysis of Bénard Convection of Magneto Rotatory Couple-Stress Fluid

NASA Astrophysics Data System (ADS)

Mehta, C. B.; Singh, M.

2018-02-01

Thermal Instability (Benard's Convection) in the presence of uniform rotation and uniform magnetic field (separately) is studied. Using the linearized stability theory and normal mode analyses the dispersion relation is obtained in each case. In the case of rotatory Benard's stationary convection compressibility and rotation postpone the onset of convection whereas the couple-stress have duel character onset of convection depending on rotation parameter. While in the absence of rotation couple-stress always postpones the onset of convection. On the other hand, magnetic field on thermal instability problem on couple-stress fluid for stationary convection couple-stress parameter and magnetic field postpones the onset of convection. The effect of compressibility also postpones the onset of convection in both cases as rotation and magnetic field. Graphs have been plotted by giving numerical values to the parameters to depict the stationary characteristics. Further, the magnetic field and rotation are found to introduce oscillatory modes which were non-existent in their absence and then the principle of exchange of stability is valid. The sufficient conditions for non-existence of overstability are also obtained.

Characteristics of phase-correcting fresnel zone plates and elliptical waveguides

NASA Astrophysics Data System (ADS)

Wiltse, James C.

1994-02-01

The primary area of activity has been concentrated on the investigations relating to Fresnel zone plate antennas. A secondary effort has dealt with the characteristics of propagation in waveguides of elliptical cross section. In both cases, applications at microwave and millimeter-wavelengths have been emphasized. Thorough literature searches were conducted, and the results are given in Appendices A and B. The zone plate work has dealt with both transmission and reflection types, and has included considering the off-axis-fed cases. In the latter case, the plate may consist of elliptical zones, rather than the usual circular configuration. In general, the characteristics studied include far-field patterns, focal region fields, off-axis performance, bandwidth, and aberrations. In the case of propagation in elliptical waveguides, the attenuation and modal properties were studied for enclosed metal waveguides, coaxial transmission lines, and various surface waveguides.

Acute nonlymphocytic leukemia and residential exposure to power frequency magnetic fields

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

Severson, R.K.

1986-01-01

A population-based case-control study of adult acute nonlymphocytic leukemia (ANLL) and residential exposure to power frequency magnetic fields was conducted in King, Pierce and Snohomish Counties in Washington state. Of 164 cases who were diagnosed from January 1, 1981 through December 31, 1984, 114 were interviewed. Controls were selected from the study area on the basis of random digit dialing and frequency matched to the cases by age and sex. Analyses were undertaken to evaluate whether exposure to high levels of power frequency magnetic fields in the residence were associated with an increased risk of ANLL. Neither the directly measuredmore » magnetic fields nor the surrogate values based on the wiring configurations were associated with ANLL. Additional analyses suggested that persons with prior allergies were at decreased risk of acute myelocytic leukemia (AML). Also, persons with prior autoimmune diseases were at increased risk of AML. The increase in AML risk in rheumatoid arthritics was of borderline statistical significance. Finally, cigarette smoking was associated with an increased risk of AML. The risk of AML increased significantly with the number of years of cigarette smoking.« less

Well-Being, Leadership, and Positive Organizational Scholarship: A Case Study of Project-Based Learning in Higher Education

ERIC Educational Resources Information Center

Lucas, Nance; Goodman, Fallon R.

2015-01-01

The emerging fields of positive psychology and positive organizational scholarship (POS) contribute new perspectives and approaches for leadership education and leadership development in higher education. While there are emerging empirical studies in these new fields, little connection has been made to the intellectual and practical applications…

The Development and Positioning of Business Related University Tourism Education: A UK Perspective.

ERIC Educational Resources Information Center

Evans, Nigel

2001-01-01

Categorization and analysis of articles on tourism research provided evidence that tourism is not a discipline but a field. A case study of a travel and tourism management program at a British university shows how business studies are emphasized in preparing for the field. (Contains 50 references.) (SK)

Field Experiences Using iPads: Impact of Experience on Preservice Teachers' Beliefs

ERIC Educational Resources Information Center

Reese, Jill A.; Bicheler, Rachel; Robinson, Callan

2016-01-01

The purpose of this phenomenological case study was to investigate the lived experiences of preservice music teachers using iPads to engage secondary general music students in creating and performing music during field teaching experiences. Two questions guided this research study: (a) What are these preservice teachers' perceptions of their…

The Diversification of the Educational Field in Hungary.

ERIC Educational Resources Information Center

Inkei, Peter; And Others

Education throughout the world has become increasingly diversified, moving from the traditional education of children to increasingly more education of adults outside formal school settings. This case study on Hungary is one of a series of studies that were conducted to map out the different components of the diversified educational field and…

The "UIC German" Game App for the Enhancement of Foreign Language Learning--Case Study

ERIC Educational Resources Information Center

Ryder, Robert; Machajewski, Szymon

2017-01-01

This qualitative case study reports the adoption of gamification in a college level foreign language courses. An exploratory approach allows the authors to describe how gamification was applied and what results were documented. A custom mobile app was adopted to increase engagement and interest of students in the specific field of study. External…

Peasant Identity: Contributions towards a Rural Psychology from an Argentinean Case Study

ERIC Educational Resources Information Center

Landini, Fernando

2012-01-01

Within the field of psychology, little attention has been paid to studying the identity of rural people, in particular the peasantry. To explore this issue, a case study was undertaken in a community located in Argentina. The research identified three different dimensions of peasants' identity. The first one, positive identity, is based on…

The Influence of Academic Values on Scholarly Publication and Communication Practices. Research and Occasional Paper Series: CSHE.13.06

ERIC Educational Resources Information Center

Harley, Diane; Earl-Novell, Sarah; Arter, Jennifer; Lawrence, Shannon; King, C. Judson

2006-01-01

This study reports on five disciplinary case studies that explore academic value systems as they influence publishing behavior and attitudes of University of California, Berkeley faculty. The case studies are based on direct interviews with relevant stakeholders--faculty, advancement reviewers, librarians, and editors--in five fields: chemical…

Gender Performativity in the Community College: A Case Study of Female Backline Classified Staff

ERIC Educational Resources Information Center

Powers, Samantha Rose

2012-01-01

This case study explored the gendered performances of five female backline classified staff members who work in non-traditional fields within a community college. More specifically, this study defined gendered behaviors at a community college, and explored how these behaviors have affected the identities of women working in non-traditional fields…

The Enterprise Training System and Training Content Analysis of Selected Manufacturing Companies in Taiwan, R.O.C.: A Case Study.

ERIC Educational Resources Information Center

Kuo, Mike Chu-Hsun

A study investigated the current enterprise training system in Taiwan and proposed suitable training suggestions for manufacturing industry through a carefully designed case study. Literature review and field study were used to gather research data. Interviews were conducted at four large manufacturing companies during the period October 1990 to…

The virtual-casing principle and Helmholtz's theorem

DOE PAGES

Hanson, J. D.

2015-09-10

The virtual-casing principle is used in plasma physics to convert a Biot–Savart integration over a current distribution into a surface integral over a surface that encloses the current. In many circumstances, use of virtual casing can significantly speed up the computation of magnetic fields. In this paper, a virtual-casing principle is derived for a general vector field with arbitrary divergence and curl. This form of the virtual-casing principle is thus applicable to both magnetostatic fields and electrostatic fields. The result is then related to Helmholtz's theorem.

The virtual-casing principle and Helmholtz’s theorem

DOE PAGES

Hanson, J. D.

2015-09-10

The virtual-casing principle is used in plasma physics to convert a Biot–Savart integration over a current distribution into a surface integral over a surface that encloses the current. In many circumstances, use of virtual casing can significantly speed up the computation of magnetic fields. In this paper, a virtual-casing principle is derived for a general vector field with arbitrary divergence and curl. This form of the virtual-casing principle is thus applicable to both magnetostatic fields and electrostatic fields. The result is then related to Helmholtz’s theorem.

ICM: Bridging the Capability Gap between 1 January 2019 and the Replacement Munition

DTIC Science & Technology

2017-06-09

fires. This qualitative case study focused on the ICM capability gap and potential solutions for the U.S. Field Artillery cannon and rocket systems... one of those countries, the United States could find itself committed in their defense. This case study will be used to provide insight to the...context of the potential ramifications of the 2008 DoD Policy on Cluster Munitions and Unintended Harm to Civilians, a case study on Russian military

The Power of Relationship Building in International Short-Term Field Study Experiences at the Graduate Level

ERIC Educational Resources Information Center

Davis, Brittany; Coryell, Joellen E.

2016-01-01

This paper derives from a case study of a 10-day cross-cultural field study experience held in Italy in which graduate students from master and doctoral levels in adult education participated. During group reflections, several students who participated in the course expressed the value of learning through personal connections made with students as…

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

ERIC Educational Resources Information Center

Skrtic, Thomas M.; And Others

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

Walking the Talk: Continuous Improvement of a Quality Management Field Exercise

ERIC Educational Resources Information Center

Coy, Steven; Adams, Jeffery

2012-01-01

This article provides results from a three semester case study of the pedagogical efficacy of an innovative quality management field exercise. A series of direct and indirect measures were used to assess the extent to which the field exercise met a set of learning objectives. The results indicate that the assessment framework is useful in…

Promoting Field Trip Confidence: Teachers Providing Insights for Pre-Service Education

ERIC Educational Resources Information Center

Ateskan, Armagan; Lane, Jennie F.

2016-01-01

Pre-service teachers need experiences in practical matters as a part of field trip preparations programmes. For 14 years, a private, non-profit university in Turkey has involved pre-service teachers in field trip planning, implementation and evaluation. A programme assessment was conducted through a case study to examine the long-term effects of…

QM-8 final performance evaluation report: SEALS, volume 4

NASA Technical Reports Server (NTRS)

Nelsen, L. V.

1989-01-01

The Space Shuttle Redesigned Solid Rocket Motor (RSRM) static test of Qualification Motor-8 (QM-8) was conducted. The QM-8 test article was the fifth full-scale, full-duration test, and the third qualification motor to incorporate the redesigned case field joint and nozzle-to-case joint. This was the second static test conducted in the T-97 test facility, which is equipped with actuators for inducing external side loads to a 360 degree external tank (ET) attach ring during test motor operation, and permits heating/cooling of an entire motor. The QM-8 motor was cooled to a temperature which ensured that the maximum propellant mean bulk temperature (PMBT) of 40 F was achieved at firing. All test results are not included, but rather, the performance of the metal case, field joints, and nozzle-to-case joint is addressed. The involvement is studied of the Structural Applications and Structural Design Groups with the QM-8 test which includes: assembly procedures of the field and nozzle-to-case joints, joint leak check results, structural test results, and post-test inspection evaluations.

Generalized Lee-Wick formulation from higher derivative field theories

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

Cho, Inyong; Kwon, O-Kab; Department of Physics, BK21 Physics Research Division, Institute of Basic Science, Sungkyunkwan University, Suwon 440-746

2010-07-15

We study a higher derivative (HD) field theory with an arbitrary order of derivative for a real scalar field. The degree of freedom for the HD field can be converted to multiple fields with canonical kinetic terms up to the overall sign. The Lagrangian describing the dynamics of the multiple fields is known as the Lee-Wick (LW) form. The first step to obtain the LW form for a given HD Lagrangian is to find an auxiliary field (AF) Lagrangian which is equivalent to the original HD Lagrangian up to the quantum level. Until now, the AF Lagrangian has been studiedmore » only for N=2 and 3 cases, where N is the number of poles of the two-point function of the HD scalar field. We construct the AF Lagrangian for arbitrary N. By the linear combinations of AF fields, we also obtain the corresponding LW form. We find the explicit mapping matrices among the HD fields, the AF fields, and the LW fields. As an exercise of our construction, we calculate the relations among parameters and mapping matrices for N=2, 3, and 4 cases.« less

[Optimal lymphadenectomy for thoracic esophageal cancer: three-field or modified two-field lymphadenectomy].

PubMed

Liu, Shuoyan; Wang, Zhen; Wang, Feng

2016-09-25

Differences in operative procedure and knowledge of esophageal cancer exist among surgeons from different countries and regions. There is controversy in the surgical treatment of esophageal cancer, especially in the extent of lymphadenectomy. Until now, results of the three-field lymphadenectomy and two-field lymphadenectomy are mostly reported by retrospective studies from Japan and China. Three-field lymphadenectomy has been initiated in Fujian Provincial Cancer Hospital since 1990s. After evaluating our database, we found that three-field was superior to two-field lymphadenectomy in terms of long-term survival for patients with upper thoracic esophageal cancer, whereas for those with middle or lower thoracic esophageal cancer, the survival benefit of three-field lymphadenectomy was reduced. Therefore, we propose to perform three-field lymphadenectomy for upper thoracic esophageal cancer. In middle or lower thoracic esophageal cancer, we suggest to perform modified two-field lymphadenectomy in most cases, and three-field lymphadenectomy in selective cases. Video-assisted two-field lymphadenectomy is feasible. Based on the national condition of China, we advise to perform thoracic duct removal only in patients with posterior mediastinal or peri-ductus node metastasis to achieve curative effect.

Nonlinear evolution of magnetic flux ropes. I - Low-beta limit

NASA Technical Reports Server (NTRS)

Osherovich, V. A.; Farrugia, C. J.; Burlaga, L. F.

1993-01-01

We study the nonlinear self-similar evolution of a cylindrical magnetic flux tube with two components of the magnetic field, axial and azimuthal. We restrict ourselves to the case of a plasma of low beta. Introducing a special class of configurations we call 'separable fields', we reduce the problem to an ordinary differential equation. Two cases are to be distinguished: (1) when the total field minimizes on the symmetry axis, the magnetic configuration inexorably collapses, and (2) when, on the other hand, the total field maximizes on the symmetry axis, the magnetic configuration behaves analogously to a nonlinear oscillator. Here we focus on the latter case. The effective potential of the motion contains two terms: a strong repulsive term and a weak restoring term associated with the pinch. We solve the nonlinear differential equation of motion numerically and find that the period of oscillations grows exponentially with the energy of the oscillator. Our treatment emphasizes the role of the force-free configuration as the lowest potential energy state about which the system oscillates.

Best Practice in Developing Critical Analyses: An Empirical Study of Self-Efficacy from an Interdisciplinary Perspective

ERIC Educational Resources Information Center

Sams, Coleen; Sams, Doreen

2011-01-01

Despite substantial usage of case study analyses as learning tools in diverse fields of study, business graduate students often arrive with little to no prior knowledge in how to effectively use this tool. Using the Sams efficacy model (2009) strategic to business education this study identified a dearth in the usage of case study analyses in…

Unsteady magnetohydrodynamic free convection flow of a second grade fluid in a porous medium with ramped wall temperature.

PubMed

Samiulhaq; Ahmad, Sohail; Vieru, Dumitru; Khan, Ilyas; Shafie, Sharidan

2014-01-01

Magnetic field influence on unsteady free convection flow of a second grade fluid near an infinite vertical flat plate with ramped wall temperature embedded in a porous medium is studied. It has been observed that magnitude of velocity as well as skin friction in case of ramped temperature is quite less than the isothermal temperature. Some special cases namely: (i) second grade fluid in the absence of magnetic field and porous medium and (ii) Newtonian fluid in the presence of magnetic field and porous medium, performing the same motion are obtained. Finally, the influence of various parameters is graphically shown.

Water liquid-vapor interface subjected to various electric fields: A molecular dynamics study.

PubMed

Nikzad, Mohammadreza; Azimian, Ahmad Reza; Rezaei, Majid; Nikzad, Safoora

2017-11-28

Investigation of the effects of E-fields on the liquid-vapor interface is essential for the study of floating water bridge and wetting phenomena. The present study employs the molecular dynamics method to investigate the effects of parallel and perpendicular E-fields on the water liquid-vapor interface. For this purpose, density distribution, number of hydrogen bonds, molecular orientation, and surface tension are examined to gain a better understanding of the interface structure. Results indicate enhancements in parallel E-field decrease the interface width and number of hydrogen bonds, while the opposite holds true in the case of perpendicular E-fields. Moreover, perpendicular fields disturb the water structure at the interface. Given that water molecules tend to be parallel to the interface plane, it is observed that perpendicular E-fields fail to realign water molecules in the field direction while the parallel ones easily do so. It is also shown that surface tension rises with increasing strength of parallel E-fields, while it reduces in the case of perpendicular E-fields. Enhancement of surface tension in the parallel field direction demonstrates how the floating water bridge forms between the beakers. Finally, it is found that application of external E-fields to the liquid-vapor interface does not lead to uniform changes in surface tension and that the liquid-vapor interfacial tension term in Young's equation should be calculated near the triple-line of the droplet. This is attributed to the multi-directional nature of the droplet surface, indicating that no constant value can be assigned to a droplet's surface tension in the presence of large electric fields.

Effects of tissue conductivity and electrode area on internal electric fields in a numerical human model for ELF contact current exposures

NASA Astrophysics Data System (ADS)

Tarao, H.; Kuisti, H.; Korpinen, L.; Hayashi, N.; Isaka, K.

2012-05-01

Contact currents flow through the human body when a conducting object with different potential is touched. There are limited reports on numerical dosimetry for contact current exposure compared with electromagnetic field exposures. In this study, using an anatomical human adult male model, we performed numerical calculation of internal electric fields resulting from 60 Hz contact current flowing from the left hand to the left foot as a basis case. Next, we performed a variety of similar calculations with varying tissue conductivity and contact area, and compared the results with the basis case. We found that very low conductivity of skin and a small electrode size enhanced the internal fields in the muscle, subcutaneous fat and skin close to the contact region. The 99th percentile value of the fields in a particular tissue type did not reliably account for these fields near the electrode. In the arm and leg, the internal fields for the muscle anisotropy were identical to those in the isotropy case using a conductivity value longitudinal to the muscle fibre. Furthermore, the internal fields in the tissues abreast of the joints such as the wrist and the elbow, including low conductivity tissues, as well as the electrode contact region, exceeded the ICNIRP basic restriction for the general public with contact current as the reference level value.

The rationale for intensity-modulated proton therapy in geometrically challenging cases

NASA Astrophysics Data System (ADS)

Safai, S.; Trofimov, A.; Adams, J. A.; Engelsman, M.; Bortfeld, T.

2013-09-01

Intensity-modulated proton therapy (IMPT) delivered with beam scanning is currently available at a limited number of proton centers. However, a simplified form of IMPT, the technique of field ‘patching’, has long been a standard practice in proton therapy centers. In field patching, different parts of the target volume are treated from different directions, i.e., a part of the tumor gets either full dose from a radiation field, or almost no dose. Thus, patching represents a form of binary intensity modulation. This study explores the limitations of the standard binary field patching technique, and evaluates possible dosimetric advantages of continuous dose modulations in IMPT. Specifics of the beam delivery technology, i.e., pencil beam scanning versus passive scattering and modulation, are not investigated. We have identified two geometries of target volumes and organs at risk (OAR) in which the use of field patching is severely challenged. We focused our investigations on two patient cases that exhibit these geometries: a paraspinal tumor case and a skull-base case. For those cases we performed treatment planning comparisons of three-dimensional conformal proton therapy (3DCPT) with field patching versus IMPT, using commercial and in-house software, respectively. We also analyzed the robustness of the resulting plans with respect to systematic setup errors of ±1 mm and range errors of ±2.5 mm. IMPT is able to better spare OAR while providing superior dose coverage for the challenging cases identified above. Both 3DCPT and IMPT are sensitive to setup errors and range uncertainties, with IMPT showing the largest effect. Nevertheless, when delivery uncertainties are taken into account IMPT plans remain superior regarding target coverage and OAR sparing. On the other hand, some clinical goals, such as the maximum dose to OAR, are more likely to be unmet with IMPT under large range errors. IMPT can potentially improve target coverage and OAR sparing in challenging cases, even when compared with the relatively complicated and time consuming field patching technique. While IMPT plans tend to be more sensitive to delivery uncertainties, their dosimetric advantage generally holds. Robust treatment planning techniques may further reduce the sensitivity of IMPT plans.

Anatomy of Advocacy: A Case Study of the White House Petition

ERIC Educational Resources Information Center

Burns, Elizabeth; Kimmel, Sue; Dickinson, Gail

2016-01-01

Little research has been conducted examining advocacy efforts in the school library field despite the fact that program advocate is a prominent role for school librarians. One element of advocacy is the engagement in political initiatives that may affect school library programs. This case study investigates the effectiveness of one advocacy effort…

Assessment of Sediment Measurements in Lake Michigan as a Case Study: Implications for Monitoring and Modeling

EPA Science Inventory

Lake Michigan, the sixth largest freshwater lake in the world by surface area, was utilized as a water body for assessment within a case study. Field data collected at 116 sediment sampling sites throughout the lake in an intensive monitoring effort were utilized for assessment ...

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

ERIC Educational Resources Information Center

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

2014-01-01

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

A Case Study of Middle Grades Leadership in a Conversion Charter School

ERIC Educational Resources Information Center

Bickmore, Dana L.; Dowell, Margaret-Mary Sulentic

2015-01-01

This 3-year case study examined middle grades principal leadership in a takeover charter school. The researcher analyzed principal and teacher interviews, field notes, and documents in relationship to a middle grades model of principal leadership. Results suggest the principals' limited experience, organizational factors unique to takeover charter…

Early Monitoring Approaches Developed from a Case Study on a Vulnerable Great Lakes Embayment

EPA Science Inventory

Great Lakes harbors/embayments are at high risk of introduction of invasive species. Monitoring is needed to inform on new introductions, and to track success of programs to limit invasion or spread. A field case study was conducted in the Duluth-Superior Harbor/St. Louis River, ...

Online Collaborative Learning in a Project-Based Learning Environment in Taiwan: A Case Study on Undergraduate Students' Perspectives

ERIC Educational Resources Information Center

Zhang, Ke; Peng, Shiang Wuu; Hung, Jui-long

2009-01-01

This case study investigated undergraduate students' first experience in online collaborative learning in a project-based learning (PBL) environment in Taiwan. Data were collected through interviews of 48 students, instructor's field notes, researchers' online observations, students' online discourse, and group artifacts. The findings revealed…

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…

It System Integration: Global Medical Acquisition of Health Tech Case Study

ERIC Educational Resources Information Center

Russo, Mark; White, Bruce

2013-01-01

Mergers and Acquisitions are just part of life in business. For example, in the health care technology field in 2012, Veritas Capital Partners acquired Thomson Reuters' Healthcare. Other major active acquisition companies included: Medical Transcription Billing, T-System Technologies and Sharecare. In this case study, a larger health technology…

Ideologies of Adventure: Authority and Decision Making in Sail Training

ERIC Educational Resources Information Center

McCulloch, Kenneth H.

2004-01-01

Case studies of the contemporary UK sail training movement are used to illustrate the competing expressions of purpose in this field. Two sail training organisations are described and a case study voyage under the aegis of each is presented. The differences between the approaches are analysed as "traditions" or ideologies, articulated…

Technology Solutions Case Study: Field Testing an Unvented Roof with Fibrous Insulation and Tiles

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

None

This case study by the U.S. Department of Energy’s Building America research team Building Science Corporation is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, Florida; zone 2A), insulated with air-permeable insulation (netted and blown fiberglass).

Merging field mapping and numerical simulation to interpret the lithofacies variations from unsteady pyroclastic density currents on uneven terrain: The case of La Fossa di Vulcano (Aeolian Islands, Italy)

NASA Astrophysics Data System (ADS)

Doronzo, Domenico M.; Dellino, Pierfrancesco; Sulpizio, Roberto; Lucchi, Federico

2017-01-01

In order to obtain results from computer simulations of explosive volcanic eruptions, one either needs a statistical approach to test a wide range of initial and boundary conditions, or needs using a well-constrained field case study via stratigraphy. Here we followed the second approach, using data obtained from field mapping of the Grotta dei Palizzi 2 pyroclastic deposits (Vulcano Island, Italy) as input for numerical modeling. This case study deals with impulsive phreatomagmatic explosions of La Fossa Cone that generated ash-rich pyroclastic density currents, interacting with the topographic high of the La Fossa Caldera rim. One of the simplifications in dealing with well-sorted ash (one particle size in the model) is to highlight the topographic effects on the same pyroclastic material in an unsteady current. We demonstrate that by merging field data with 3D numerical simulation results it is possible to see key details of the dynamical current-terrain interaction, and to interpret the lithofacies variations of the associated deposits as a function of topography-induced sedimentation (settling) rate. Results suggest that a value of the sedimentation rate lower than 5 kg/m2 s at the bed load can still be sheared by the overlying current, producing tractional structures (laminae) in the deposits. Instead, a sedimentation rate higher than that threshold can preclude the formation of tractional structures, producing thicker massive deposits. We think that the approach used in this study could be applied to other case studies (both for active and ancient volcanoes) to confirm or refine such threshold value of the sedimentation rate, which is to be considered as an upper value as for the limitations of the numerical model.

Risk-Based, Hypothesis-Driven Framework for Hydrological Field Campaigns with Case Studies

NASA Astrophysics Data System (ADS)

Harken, B.; Rubin, Y.

2014-12-01

There are several stages in any hydrological modeling campaign, including: formulation and analysis of a priori information, data acquisition through field campaigns, inverse modeling, and prediction of some environmental performance metric (EPM). The EPM being predicted could be, for example, contaminant concentration or plume travel time. These predictions often have significant bearing on a decision that must be made. Examples include: how to allocate limited remediation resources between contaminated groundwater sites or where to place a waste repository site. Answering such questions depends on predictions of EPMs using forward models as well as levels of uncertainty related to these predictions. Uncertainty in EPM predictions stems from uncertainty in model parameters, which can be reduced by measurements taken in field campaigns. The costly nature of field measurements motivates a rational basis for determining a measurement strategy that is optimal with respect to the uncertainty in the EPM prediction. The tool of hypothesis testing allows this uncertainty to be quantified by computing the significance of the test resulting from a proposed field campaign. The significance of the test gives a rational basis for determining the optimality of a proposed field campaign. This hypothesis testing framework is demonstrated and discussed using various synthetic case studies. This study involves contaminated aquifers where a decision must be made based on prediction of when a contaminant will arrive at a specified location. The EPM, in this case contaminant travel time, is cast into the hypothesis testing framework. The null hypothesis states that the contaminant plume will arrive at the specified location before a critical amount of time passes, and the alternative hypothesis states that the plume will arrive after the critical time passes. The optimality of different field campaigns is assessed by computing the significance of the test resulting from each one. Evaluating the level of significance caused by a field campaign involves steps including likelihood-based inverse modeling and semi-analytical conditional particle tracking.

Evolution of Kelvin-Helmholtz instability at Venus in the presence of the parallel magnetic field

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

Lu, H. Y.; Key Laboratory of Planetary Sciences, Chinese Academy of Sciences, Nanjing 210008; Cao, J. B.

2015-06-15

Two-dimensional MHD simulations were performed to study the evolution of the Kelvin-Helmholtz (KH) instability at the Venusian ionopause in response to the strong flow shear in presence of the in-plane magnetic field parallel to the flow direction. The physical behavior of the KH instability as well as the triggering and occurrence conditions for highly rolled-up vortices are characterized through several physical parameters, including Alfvén Mach number on the upper side of the layer, the density ratio, and the ratio of parallel magnetic fields between two sides of the layer. Using these parameters, the simulations show that both the high densitymore » ratio and the parallel magnetic field component across the boundary layer play a role of stabilizing the instability. In the high density ratio case, the amount of total magnetic energy in the final quasi-steady status is much more than that in the initial status, which is clearly different from the case with low density ratio. We particularly investigate the nonlinear development of the case that has a high density ratio and uniform magnetic field. Before the instability saturation, a single magnetic island is formed and evolves into two quasi-steady islands in the non-linear phase. A quasi-steady pattern eventually forms and is embedded within a uniform magnetic field and a broadened boundary layer. The estimation of loss rates of ions from Venus indicates that the stabilizing effect of the parallel magnetic field component on the KH instability becomes strong in the case of high density ratio.« less

Investigating the role of Fuzzy as confirmatory tool for service quality assessment (Case study: Comparison of Fuzzy SERVQUAL and SERVQUAL in hotel service evaluation)

NASA Astrophysics Data System (ADS)

Wahyudi, R. D.

2017-11-01

The problem was because of some indicators qualitatively assessed had been discussed in engineering field. Whereas, qualitative assessment was presently used in certain occasion including in engineering field, for instance, the assessment of service satisfaction. Probably, understanding of satisfaction definition caused bias if customers had their own definition of satisfactory level of service. Therefore, the use of fuzzy logic in SERVQUAL as service satisfaction measurement tool would probably be useful. This paper aimed to investigate the role of fuzzy in SERVQUAL by comparing result measurement of SERVQUAL and fuzzy SERVQUAL for study case of hotel service evaluation. Based on data processing, initial result showed that there was no significant different between them. Thus, either implementation of fuzzy SERVQUAL in different case or study about the role of fuzzy logic in SERVQUAL would be interesting further discussed topic.

Numerical simulation of turbulent Taylor-Couette flow between conducting cylinders in an axial magnetic field at low magnetic Reynolds number

NASA Astrophysics Data System (ADS)

Leng, Xueyuan; Kolesnikov, Yurii B.; Krasnov, Dmitry; Li, Benwen

2018-01-01

The effect of an axial homogeneous magnetic field on the turbulence in the Taylor-Couette flow confined between two infinitely long conducting cylinders is studied by the direct numerical simulation using a periodic boundary condition in the axial direction. The inner cylinder is rotating, and the outer one is fixed. We consider the case when the magnetic Reynolds number Rem ≪ 1, i.e., the influence of the induced magnetic field on the flow is negligible that is typical for industry and laboratory study of liquid metals. Relevance of the present study is based on the similarity of flow characteristics at moderate and high magnetic field for the cases with periodic and end-wall conditions at the large flow aspect ratio, as proven in the earlier studies. Two sets of Reynolds numbers 4000 and 8000 with several Hartmann numbers varying from 0 to 120 are employed. The results show that the mean radial induced electrical current, resulting from the interaction of axial magnetic field with the mean flow, leads to the transformation of the mean flow and the modification of the turbulent structure. The effect of turbulence suppression is dominating at a strong magnetic field, but before reaching the complete laminarization, we capture the appearance of the hairpin-like structures in the flow.

A Case Study on the Experiences of University-Based Muslim Women in Physical Activity during Their Studies at One UK Higher Education Institution

ERIC Educational Resources Information Center

Miles, Claire; Benn, Tansin

2016-01-01

The case study explores the experiences of Muslim women in the area of physical activity participation conducted whilst they were studying at one UK University. Previous research in the field indicated that Muslim women can be denied opportunities to participate in areas of sport-related physical activity through multiple factors such as…

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

Hanson, J. D.

The virtual-casing principle is used in plasma physics to convert a Biot–Savart integration over a current distribution into a surface integral over a surface that encloses the current. In many circumstances, use of virtual casing can significantly speed up the computation of magnetic fields. In this paper, a virtual-casing principle is derived for a general vector field with arbitrary divergence and curl. This form of the virtual-casing principle is thus applicable to both magnetostatic fields and electrostatic fields. The result is then related to Helmholtz's theorem.

The Contribution of HBCUS to the Preparation of African American Women for STEM Careers: A Case Study

ERIC Educational Resources Information Center

Perna, Laura; Lundy-Wagner, Valerie; Drezner, Noah D.; Gasman, Marybeth; Yoon, Susan; Bose, Enakshi; Gary, Shannon

2009-01-01

This study uses case study analysis to explore the ways that Spelman College, a historically Black women's college, promotes the attainment of African American women in STEM fields. Although limited to one institution, the findings shed light on the ways that institutional characteristics, policies, and practices may mitigate the barriers that…

The UMO (University of Maine, Orono) Teacher Training Program: A Case Study and a Model.

ERIC Educational Resources Information Center

Miller, James R.; McNally, Harry

This case study presents a model of the University of Maine, Orono, pre-service program for preparing secondary social studies teachers. Focus is on the Foundations Component and the Methods Component, either of which can function independently of the other. Only brief mention is made of either the Exploratory Field Experience Component or the…

Cases on Interdisciplinary Research Trends in Science, Technology, Engineering, and Mathematics: Studies on Urban Classrooms. Advances in Educational Technologies and Instructional Design

ERIC Educational Resources Information Center

Lansiquot, Reneta D.

2013-01-01

Involving two or more academic subjects, interdisciplinary studies aim to blend together broad perspectives, knowledge, skills, and epistemology in an educational setting. By focusing on topics or questions too broad for a single discipline to cover, these studies strive to draw connections between seemingly different fields. Cases on…

Environmental Comfort in School Buildings: A Case Study of Awareness and Participation of Users

ERIC Educational Resources Information Center

Bernardi, Nubia; Kowaltowski, Doris C. C. K.

2006-01-01

This article describes the results of a study on user behavior in relation to environmental comfort conditions. A case study was conducted in school buildings in the region of the city of Campinas, So Paulo, Brazil. The methodology adopted was based on field observations of technical aspects of the school environment and of types of user behavior…

Young Workers and Their Dispositions towards Mathematics: Tensions of a Mathematical Habitus in the Retail Industry

ERIC Educational Resources Information Center

Jorgensen Zebenbergen, Robyn

2011-01-01

This paper presents a case study of contemporary retail industry and the ways in which young workers participate in that field. Public perceptions of low numeracy among young people provided the catalyst for the study. Drawing on a mixed-method approach involving survey, case studies, stimulated recall, observations, and interviews, it was found…

Examining Graduate Dissertations in the Field of Critical Thinking: A Case from Turkey

ERIC Educational Resources Information Center

Demirel, Melek; Derman, Ipek; Can Aran, Ozge

2017-01-01

Purpose: The aim of this study is to conduct content analyses of graduate dissertations about critical thinking skills in the field of educational sciences in Turkey and to document general trends in dissertations. Research Methods: This study is constructed using qualitative research methods and techniques. A document review was used to gather…

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.

Nonlinear wave interaction in a plasma column

NASA Technical Reports Server (NTRS)

Larsen, J.

1972-01-01

Two particular cases of nonlinear wave interaction in a plasma column were investigated. The frequencies of the waves were on the order of magnitude of the electron plasma frequency, and ion motion was neglected. The nonlinear coupling of slow waves on a plasma column was studied by means of cold plasma theory, and the case of a plasma column surrounded by an infinite dielectric in the absence of a magnetic field was also examined. Nonlinear scattering from a plasma column in an electromagnetic field having it's magnetic field parallel to the axis of the column was investigated. Some experimental results on mode conversion in the presence of loss are presented along with some observations of nonlinear scattering, The effect of the earth's magnetic field and of discharge symmetry on the radiation pattern are discussed.

Fast electric control of the droplet size in a microfluidic T-junction droplet generator

NASA Astrophysics Data System (ADS)

Shojaeian, Mostafa; Hardt, Steffen

2018-05-01

The effect of DC electric fields on the generation of droplets of water and xanthan gum solutions in sunflower oil at a microfluidic T-junction is experimentally studied. The electric field leads to a significant reduction of the droplet diameter, by about a factor of 2 in the case of water droplets. The droplet size can be tuned by varying the electric field strength, an effect that can be employed to produce a stream of droplets with a tailor-made size sequence. Compared to the case of purely hydrodynamic droplet production without electric fields, the electric control has about the same effect on the droplet size if the electric stress at the liquid/liquid interface is the same as the hydrodynamic stress.

Information Systems Education in Kenya: Students' Specialization Choice Trends (A Case Study of Kenya Polytechnic University College)

ERIC Educational Resources Information Center

Ndede-Amadi, Atieno A.

2013-01-01

The objective of this study was to determine the time and level of Information Systems (IS) awareness among Kenyan university students and the choice of IS as a field of specialization. The study posited that the choice of a field of specialization is dependent upon a student's awareness of its existence, its utilization in the real world, its…

Infinite coherence time of edge spins in finite-length chains

NASA Astrophysics Data System (ADS)

Maceira, Ivo A.; Mila, Frédéric

2018-02-01

Motivated by the recent observation that exponentially long coherence times can be achieved for edge spins in models with strong zero modes, we study the impact of level crossings in finite-length spin chains on the dynamics of the edge spins. Focusing on the X Y spin-1 /2 chain with a transverse or longitudinal magnetic field, two models relevant to understanding recent experimental results on cobalt adatoms, we show that the edge spins can remain coherent for an infinite time even for a finite-length chain if the magnetic field is tuned to a value at which there is a level crossing. Furthermore, we show that the edge spins remain coherent for any initial state for the integrable case of a transverse field because all states have level crossings at the same value of the field, while the coherence time is increasingly large for lower temperatures in the case of a longitudinal field, which is nonintegrable.

Theoretical study on the laser-driven ion-beam trace probe in toroidal devices with large poloidal magnetic field

NASA Astrophysics Data System (ADS)

Yang, X.; Xiao, C.; Chen, Y.; Xu, T.; Yu, Y.; Xu, M.; Wang, L.; Wang, X.; Lin, C.

2018-03-01

Recently, a new diagnostic method, Laser-driven Ion-beam Trace Probe (LITP), has been proposed to reconstruct 2D profiles of the poloidal magnetic field (Bp) and radial electric field (Er) in the tokamak devices. A linear assumption and test particle model were used in those reconstructions. In some toroidal devices such as the spherical tokamak and the Reversal Field Pinch (RFP), Bp is not small enough to meet the linear assumption. In those cases, the error of reconstruction increases quickly when Bp is larger than 10% of the toroidal magnetic field (Bt), and the previous test particle model may cause large error in the tomography process. Here a nonlinear reconstruction method is proposed for those cases. Preliminary numerical results show that LITP could be applied not only in tokamak devices, but also in other toroidal devices, such as the spherical tokamak, RFP, etc.

A comparison between GO/aperture-field and physical-optics methods for offset reflectors

NASA Technical Reports Server (NTRS)

Rahmat-Samii, Y.

1984-01-01

Both geometrical optics (GO)/aperture-field and physical-optics (PO) methods are used extensively in the diffraction analysis of offset parabolic and dual reflectors. An analytical/numerical comparative study is performed to demonstrate the limitations of the GO/aperture-field method for accurately predicting the sidelobe and null positions and levels. In particular, it is shown that for offset parabolic reflectors and for feeds located at the focal point, the predicted far-field patterns (amplitude) by the GO/aperture-field method will always be symmetric even in the offset plane. This, of course, is inaccurate for the general case and it is shown that the physical-optics method can result in asymmetric patterns for cases in which the feed is located at the focal point. Representative numerical data are presented and a comparison is made with available measured data.

100 top-cited scientific papers in limb prosthetics.

PubMed

Eshraghi, Arezoo; Osman, Noor Azuan Abu; Gholizadeh, Hossein; Ali, Sadeeq; Shadgan, Babak

2013-11-17

Research has tremendously contributed to the developments in both practical and fundamental aspects of limb prosthetics. These advancements are reflected in scientific articles, particularly in the most cited papers. This article aimed to identify the 100 top-cited articles in the field of limb prosthetics and to investigate their main characteristics. Articles related to the field of limb prosthetics and published in the Web of Knowledge database of the Institute for Scientific Information (ISI) from the period of 1980 to 2012. The 100 most cited articles in limb prosthetics were selected based on the citation index report. All types of articles except for proceedings and letters were included in the study. The study design and level of evidence were determined using Sackett's initial rules of evidence. The level of evidence was categorized either as a systematic review or meta-analysis, randomized controlled trial, cohort study, case-control study, case series, expert opinion, or design and development. The top cited articles in prosthetics were published from 1980 to 2012 with a citation range of 11 to 90 times since publication. The mean citation rate was 24.43 (SD 16.7) times. Eighty-four percent of the articles were original publications and were most commonly prospective (76%) and case series studies (67%) that used human subjects (96%) providing level 4 evidence. Among the various fields, rehabilitation (47%), orthopedics (29%), and sport sciences (28%) were the most common fields of study. The study established that studies conducted in North America and were written in English had the highest citations. Top cited articles primarily dealt with lower limb prosthetics, specifically, on transtibial and transradial prosthetic limbs. Majority of the articles were experimental studies.

Science Teacher Education for Sustainable Development: A Case Study of a Residential Field Course in a Norwegian Pre-Service Teacher Education Programme

ERIC Educational Resources Information Center

Jegstad, Kirsti Marie; Gjøtterud, Sigrid Marie; Sinnes, Astrid Tonette

2018-01-01

In this paper, we explore how a Norwegian teacher education institution promotes education for sustainable development (ESD) through a residential field course. The residential field course was located in a mountain area and data were collected through participant observation. The data included--together with instructional artefacts--evaluation…

Engineering, Technology and Science Disciplines and Gender Difference: A Case Study among Indian Students

ERIC Educational Resources Information Center

Cheruvalath, Reena

2018-01-01

It is proposed to examine the argument that females cannot perform better in engineering and science fields because of their poor mathematical or logical reasoning. The major reason for the reduced number of females in the above fields in India is the socio-cultural aversion towards females choosing the field and restriction in providing higher…

Observations of a Newly "Captured" Magnetosheath Field Line: Evidence for "Double Reconnection"

NASA Technical Reports Server (NTRS)

Chandler, Michael O.; Avanov, Levon A.; Craven, Paul D.; Mozer, Forrest S.; Moore, Thomas E.

2007-01-01

We have begun an investigation of the nature of the low-latitude boundary layer in the mid-altitude cusp region using data from the Polar spacecraft. This region has been routinely sampled for about three months each year for the periods 1999-2001 and 2004-2006. The low-to-mid-energy ion instruments frequently observed dense, magnetosheath-like plasma deep (in terms of distance from the magnetopause and in invariant latitude) in the magnetosphere. One such case, taken during a period of northward interplanetary magnetic field (IMF), shows magnetosheath ions within the magnetosphere with velocity distributions resulting from two separate merging sites along the same field lines. Cold ionospheric ions were also observed counterstreaming along the field lines, evidence that these field lines were closed. These results are consistent with the hypothesis that double merging can produce closed field .lines populated by solar wind plasma. Through the use of individual cases such as this and statistical studies of a broader database we seek to understand the morphology of the LLBL as it projects from the sub-solar region into the cusp. We will present preliminary results of our ongoing study.

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

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

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

1985-01-01

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

Chiral symmetry breaking in a semilocalized magnetic field

NASA Astrophysics Data System (ADS)

Cao, Gaoqing

2018-03-01

In this work, we explore the pattern of chiral symmetry breaking and restoration in a solvable magnetic field configuration within the Nambu-Jona-Lasinio model. The special semilocalized static magnetic field can roughly mimic the realistic situation in peripheral heavy ion collisions; thus, the study is important for the dynamical evolution of quark matter. We find that the magnetic-field-dependent contribution from discrete spectra usually dominates over the contribution from continuum spectra and chiral symmetry breaking is locally catalyzed by both the magnitude and scale of the magnetic field. The study is finally extended to the case with finite temperature or chemical potential.

Merging field mapping and modeling to interpret the lithofacies variations from unsteady ash-rich pyroclastic density currents on uneven topography

NASA Astrophysics Data System (ADS)

Doronzo, Domenico; Dellino, Pierfrancesco; Sulpizio, Roberto; Lucchi, Federico

2017-04-01

In order to obtain significant volcanological results from computer simulations of explosive eruptions, one either needs a systematic statistical approach to test a wide range of initial and boundary conditions, or needs using a well-constrained field case study. Here we followed the second approach, using data obtained from field mapping of the Grotta dei Palizzi 2 pyroclastic deposits (Vulcano Island, Italy) as input for numerical modeling. This case study deals with impulsive phreatomagmatic explosions that generated ash-rich pyroclastic density currents, interacting with the high topographic obstacle of the La Fossa Caldera rim. We demonstrate that by merging field data with 3D numerical simulation it is possible to highlight the details of the dynamical current-terrain interaction, and to interpret the lithofacies variations of the associated deposits as a function of topography-induced sedimentation rate. Results suggest that a value of the sedimentation rate lower than 5 kg/m2s at the bed load can still be sheared by the overlying current, producing tractional structures in the deposit. Instead, a sedimentation rate in excess of that threshold can preclude the formation of tractional structures, producing thick massive deposits. We think that the approach used in this study could be applied to other case studies to confirm or refine such threshold value of the sedimentation rate, which is to be considered as an upper value as for the limitations of the numerical model.

Anisotropic inflation with derivative couplings

NASA Astrophysics Data System (ADS)

Holland, Jonathan; Kanno, Sugumi; Zavala, Ivonne

2018-05-01

We study anisotropic power-law inflationary solutions when the inflaton and its derivative couple to a vector field. This type of coupling is motivated by D-brane inflationary models, in which the inflaton, and a vector field living on the D-brane, couple disformally (derivatively). We start by studying a phenomenological model where we show the existence of anisotropic solutions and demonstrate their stability via a dynamical system analysis. Compared to the case without a derivative coupling, the anisotropy is reduced and thus can be made consistent with current limits, while the value of the slow-roll parameter remains almost unchanged. We also discuss solutions for more general cases, including D-brane-like couplings.

A parametric shell analysis of the shuttle 51-L SRB AFT field joint

NASA Technical Reports Server (NTRS)

Davis, Randall C.; Bowman, Lynn M.; Hughes, Robert M., IV; Jackson, Brian J.

1990-01-01

Following the Shuttle 51-L accident, an investigation was conducted to determine the cause of the failure. Investigators at the Langley Research Center focused attention on the structural behavior of the field joints with O-ring seals in the steel solid rocket booster (SRB) cases. The shell-of-revolution computer program BOSOR4 was used to model the aft field joint of the solid rocket booster case. The shell model consisted of the SRB wall and joint geometry present during the Shuttle 51-L flight. A parametric study of the joint was performed on the geometry, including joint clearances, contact between the joint components, and on the loads, induced and applied. In addition combinations of geometry and loads were evaluated. The analytical results from the parametric study showed that contact between the joint components was a primary contributor to allowing hot gases to blow by the O-rings. Based upon understanding the original joint behavior, various proposed joint modifications are shown and analyzed in order to provide additional insight and information. Finally, experimental results from a hydro-static pressurization of a test rocket booster case to study joint motion are presented and verified analytically.

Field Trips and the Law.

ERIC Educational Resources Information Center

Troy, Thomas D.; Schwaab, Karl E.

1981-01-01

Legal aspects of field trips are addressed, with special attention on planning and implementation aspects which warrant legal consideration. Suggestions are based on information obtained from studies which reviewed and analyzed court cases, with recommendations geared to lessen the likelihood that negligence suits will result if students sustain…

Improving precision of forage yield trials: A case study

USDA-ARS?s Scientific Manuscript database

Field-based agronomic and genetic research relies heavily on the data generated from field evaluations. Therefore, it is imperative to optimize the precision of yield estimates in cultivar evaluation trials to make reliable selections. Experimental error in yield trials is sensitive to several facto...

An investigation of the magnetic field of Transient Disturbances (TD) at the Earth's orbit, and a determination of solar sources of TD from their characteristics at R = 1 AU

NASA Technical Reports Server (NTRS)

Fainshtein, V. .G.; Kaigorodov, A. P.

1995-01-01

We have investigated and intercompared the typical features of the magnetic field of two types of solar wind transient disturbances with shock waves: the shock wave is accompanied by a magnetic cloud (MC), and the shock wave is followed by a region with bidirectional solar wind electron heat flux (BEHF), with no MC present. In this case, a separate study was made of the field features in two typical TD structures: in the region of impact-compressed solar wind between the shock wave and MC or BEHF, as well as in MC and BEHF. The study has provided new results on the influence of the ambient SW upon the TD magnetic field and the relationship between fields in various TD structures. A new test for the existence of interplanetary magnetic field draping around MC and BEHF is proposed and verified. It is concluded that the magnetic field configuration around MC is more adequately consistent with the concept of magnetic line draping than is the case around BEHF Two methods are proposed to infer the location of solar sources of TD from their characteristics at R = 1 AU.

Automated Peak Detection and Matching Algorithm for Gas Chromatography–Differential Mobility Spectrometry

PubMed Central

Fong, Sim S.; Rearden, Preshious; Kanchagar, Chitra; Sassetti, Christopher; Trevejo, Jose; Brereton, Richard G.

2013-01-01

A gas chromatography–differential mobility spectrometer (GC-DMS) involves a portable and selective mass analyzer that may be applied to chemical detection in the field. Existing approaches examine whole profiles and do not attempt to resolve peaks. A new approach for peak detection in the 2D GC-DMS chromatograms is reported. This method is demonstrated on three case studies: a simulated case study; a case study of headspace gas analysis of Mycobacterium tuberculosis (MTb) cultures consisting of three matching GC-DMS and GC-MS chromatograms; a case study consisting of 41 GC-DMS chromatograms of headspace gas analysis of MTb culture and media. PMID:21204557

On scalar and vector fields coupled to the energy-momentum tensor

NASA Astrophysics Data System (ADS)

Jiménez, Jose Beltrán; Cembranos, Jose A. R.; Sánchez Velázquez, Jose M.

2018-05-01

We consider theories for scalar and vector fields coupled to the energy-momentum tensor. Since these fields also carry a non-trivial energy-momentum tensor, the coupling prescription generates self-interactions. In analogy with gravity theories, we build the action by means of an iterative process that leads to an infinite series, which can be resumed as the solution of a set of differential equations. We show that, in some particular cases, the equations become algebraic and that is also possible to find solutions in the form of polynomials. We briefly review the case of the scalar field that has already been studied in the literature and extend the analysis to the case of derivative (disformal) couplings. We then explore theories with vector fields, distinguishing between gauge-and non-gauge-invariant couplings. Interactions with matter are also considered, taking a scalar field as a proxy for the matter sector. We also discuss the ambiguity introduced by superpotential (boundary) terms in the definition of the energy-momentum tensor and use them to show that it is also possible to generate Galileon-like interactions with this procedure. We finally use collider and astrophysical observations to set constraints on the dimensionful coupling which characterises the phenomenology of these models.

Using Acceptance and Commitment Therapy to Treat Distressed Couples: A Case Study With Two Couples

ERIC Educational Resources Information Center

Peterson, Brennan D.; Eifert, Georg H.; Feingold, Tal; Davidson, Sarah

2009-01-01

Although the field of couple therapy has made significant strides in recent years, there continues to be a need for theoretically sound and empirically supported treatments. The current case study examines whether Acceptance and Commitment Therapy (ACT), an experiential acceptance-based behavior therapy, can be effective in treating distressed…

International Child Welfare: Guidelines for Educators and a Case Study from Cyprus

ERIC Educational Resources Information Center

Howe, Tasha R.

2010-01-01

This article outlines challenges and opportunities educators and students face while attempting to develop a global perspective in social work. It discusses the need for more international focus in the classroom and increased field placements in non-Western countries. Exercises using an in-depth case study of the historic and current dynamics of…

Minority Voices: A Case Study of Children and Parents in a Manchester Primary School

ERIC Educational Resources Information Center

Winterbottom, Christian; Leedy, Allyson K.

2014-01-01

Presently, there are a growing number of ethnic minority students in the primary schools in northwest England. Through sociocultural theory, this paper examines student and parent perspectives of their experiences in the schools. Using a qualitative methodology, including observation, in-depth interviews, and field notes this case study focused on…

Discourses of Education, Protection, and Child Labor: Case Studies of Benin, Namibia and Swaziland

ERIC Educational Resources Information Center

Nordtveit, Bjorn Harald

2010-01-01

This article analyses discontinuities between local, national and international discourse in the fields of education, protection of children, and child labor, using Benin, Namibia and Swaziland as case studies. In Benin, child abuse and child labor are related to poverty, whereas in Namibia and Swaziland they are also interrelated with HIV/AIDS.…

From Student-Athlete to Student-Teacher: A Case Study of One Student's Journey

ERIC Educational Resources Information Center

Caniglia, Joanne; Pellegrino, Christine

2014-01-01

The purpose of this study was to investigate and describe patterns of behavior that a student-athlete not only exhibits during athletic competition, but also transfers from the soccer field to the college classroom and to the teaching profession. Using journals, lesson plans, teaching commentaries, videos, and interviews, a qualitative case study…

Design Fixation and Cooperative Learning in Elementary Engineering Design Project: A Case Study

ERIC Educational Resources Information Center

Luo, Yi

2015-01-01

This paper presents a case study examining 3rd, 4th and 5th graders' design fixation and cooperative learning in an engineering design project. A mixed methods instrument, the Cooperative Learning Observation Protocol (CLOP), was adapted to record frequency and class observation on cooperative learning engagement through detailed field notes.…

Translanguaging Practices at a Bilingual University: A Case Study of a Science Classroom

ERIC Educational Resources Information Center

Mazak, Catherine M.; Herbas-Donoso, Claudia

2015-01-01

The objective of this ethnographic case study is to describe in detail one professor's translanguaging practices in an undergraduate science course at an officially bilingual university. The data-set is comprised of ethnographic field notes of 11 observed classes, audio recordings of those classes, an interview with the professor, and artifacts…

Inflationary magneto-(non)genesis, increasing kinetic couplings, and the strong coupling problem

NASA Astrophysics Data System (ADS)

Bazrafshan Moghaddam, Hossein; McDonough, Evan; Namba, Ryo; Brandenberger, Robert H.

2018-05-01

We study the generation of magnetic fields during inflation making use of a coupling of the inflaton and moduli fields to electromagnetism via the photon kinetic term, and assuming that the coupling is an increasing function of time. We demonstrate that the strong coupling problem of inflationary magnetogenesis can be avoided by incorporating the destabilization of moduli fields after inflation. The magnetic field always dominates over the electric one, and thus the severe constraints on the latter from backreaction, which are the demanding obstacles in the case of a decreasing coupling function, do not apply to the current scenario. However, we show that this loophole to the strong coupling problem comes at a price: the normalization of the amplitude of magnetic fields is determined by this coupling term and is therefore suppressed by a large factor after the moduli destabilization completes. From this we conclude that there is no self-consistent and generic realization of primordial magnetogenesis producing scale-invariant fields in the case of an increasing kinetic coupling.

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

NASA Astrophysics Data System (ADS)

Lazanja, David; Boozer, Allen

2006-10-01

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

Electron and donor-impurity-related Raman scattering and Raman gain in triangular quantum dots under an applied electric field

NASA Astrophysics Data System (ADS)

Tiutiunnyk, Anton; Akimov, Volodymyr; Tulupenko, Viktor; Mora-Ramos, Miguel E.; Kasapoglu, Esin; Morales, Alvaro L.; Duque, Carlos Alberto

2016-04-01

The differential cross-section of electron Raman scattering and the Raman gain are calculated and analysed in the case of prismatic quantum dots with equilateral triangle base shape. The study takes into account their dependencies on the size of the triangle, the influence of externally applied electric field as well as the presence of an ionized donor center located at the triangle's orthocenter. The calculations are made within the effective mass and parabolic band approximations, with a diagonalization scheme being applied to obtain the eigenfunctions and eigenvalues of the x- y Hamiltonian. The incident and secondary (scattered) radiation have been considered linearly-polarized along the y-direction, coinciding with the direction of the applied electric field. For the case with an impurity center, Raman scattering with the intermediate state energy below the initial state one has been found to show maximum differential cross-section more than by an order of magnitude bigger than that resulting from the scheme with lower intermediate state energy. The Raman gain has maximum magnitude around 35 nm dot size and electric field of 40 kV/cm for the case without impurity and at maximum considered values of the input parameters for the case with impurity. Values of Raman gain of the order of up to 104cm-1 are predicted in both cases.

Use of the Outdoor Classroom and Nature-Study to Support Science and Literacy Learning: A Narrative Case Study of a Third-Grade Classroom

ERIC Educational Resources Information Center

Eick, Charles J.

2012-01-01

A case study of an exemplary third grade teacher's use of the outdoor classroom for meeting both state science and language arts standards is described. Data from the researcher's field journal, teacher lesson plans, and teacher interviews document how this teacher used nature-study to bridge outdoor classroom experiences with the state science…

Computer Science and Engineering Students Addressing Critical Issues Regarding Gender Differences in Computing: A Case Study

ERIC Educational Resources Information Center

Tsagala, Evrikleia; Kordaki, Maria

2008-01-01

This study focuses on how Computer Science and Engineering Students (CSESs) of both genders address certain critical issues for gender differences in the field of Computer Science and Engineering (CSE). This case study is based on research conducted on a sample of 99 Greek CSESs, 43 of which were women. More specifically, these students were asked…

Scalar fields in black hole spacetimes

NASA Astrophysics Data System (ADS)

Thuestad, Izak; Khanna, Gaurav; Price, Richard H.

2017-07-01

The time evolution of matter fields in black hole exterior spacetimes is a well-studied subject, spanning several decades of research. However, the behavior of fields in the black hole interior spacetime has only relatively recently begun receiving some attention from the research community. In this paper, we numerically study the late-time evolution of scalar fields in both Schwarzschild and Kerr spacetimes, including the black hole interior. We recover the expected late-time power-law "tails" on the exterior (null infinity, timelike infinity, and the horizon). In the interior region, we find an interesting oscillatory behavior that is characterized by the multipole index ℓ of the scalar field. In addition, we also study the extremal Kerr case and find strong indications of an instability developing at the horizon.

Spectral density mapping at multiple magnetic fields suitable for 13C NMR relaxation studies

NASA Astrophysics Data System (ADS)

Kadeřávek, Pavel; Zapletal, Vojtěch; Fiala, Radovan; Srb, Pavel; Padrta, Petr; Přecechtělová, Jana Pavlíková; Šoltésová, Mária; Kowalewski, Jozef; Widmalm, Göran; Chmelík, Josef; Sklenář, Vladimír; Žídek, Lukáš

2016-05-01

Standard spectral density mapping protocols, well suited for the analysis of 15N relaxation rates, introduce significant systematic errors when applied to 13C relaxation data, especially if the dynamics is dominated by motions with short correlation times (small molecules, dynamic residues of macromolecules). A possibility to improve the accuracy by employing cross-correlated relaxation rates and on measurements taken at several magnetic fields has been examined. A suite of protocols for analyzing such data has been developed and their performance tested. Applicability of the proposed protocols is documented in two case studies, spectral density mapping of a uniformly labeled RNA hairpin and of a selectively labeled disaccharide exhibiting highly anisotropic tumbling. Combination of auto- and cross-correlated relaxation data acquired at three magnetic fields was applied in the former case in order to separate effects of fast motions and conformational or chemical exchange. An approach using auto-correlated relaxation rates acquired at five magnetic fields, applicable to anisotropically moving molecules, was used in the latter case. The results were compared with a more advanced analysis of data obtained by interpolation of auto-correlated relaxation rates measured at seven magnetic fields, and with the spectral density mapping of cross-correlated relaxation rates. The results showed that sufficiently accurate values of auto- and cross-correlated spectral density functions at zero and 13C frequencies can be obtained from data acquired at three magnetic fields for uniformly 13C -labeled molecules with a moderate anisotropy of the rotational diffusion tensor. Analysis of auto-correlated relaxation rates at five magnetic fields represents an alternative for molecules undergoing highly anisotropic motions.

Academic Leaderships Views of School Psychology and Black Students: The Case of Historically Black Colleges and Universities

ERIC Educational Resources Information Center

Beeks, Amirah; Graves, Scott L., Jr.

2017-01-01

The purpose of this study was to understand academic leadership's views of the field of school psychology. This is the first study that has attempted to incorporate the views of historically Black college and university (HBCU) Psychology Department Chairs' regarding the field of school psychology and the potential development of school psychology…

Early Urban Field Experiences for Prospective Teachers: A Case Study of Multicultural Field Placements through a University-Based Preservice STEM Teacher Program

ERIC Educational Resources Information Center

Segal, Eden H.

2011-01-01

Educational and political leaders have expressed concern about racial and ethnic disparities in students' readiness for postsecondary study and careers in science, technology, engineering, and mathematics (STEM). A lack of preparedness of STEM teachers in high-need urban districts, which serve predominantly low-income minority students, is often…

Occupational and Qualification Structures in the Field of Environmental Protection in the Metal and Chemical Industries in the United Kingdom.

ERIC Educational Resources Information Center

European Centre for the Development of Vocational Training, Berlin (Germany).

A study analyzed the occupational structure and qualifications associated with the field of environmental protection in the metal and chemical industries in the United Kingdom. The analysis included nine case studies based on interviews with firms in the chemicals and metals sectors. Information was gathered within an analytical framework that…

Theoretical and Computational Studies of Stability, Transition and Flow Control in High-Speed Flows

DTIC Science & Technology

2008-02-14

subsonic perturbations, there is an overlapping of four modes. This case has not been considered yet elsewhere. Similarly to the other cases , one can derive...weights for the vorticity and entropy modes. Similarly to the incompressible case [Tum03], one can see that there is a discrepancy between the...turbulence’ [FK01]. In conventional computational studies , one could observe the generation of the instability mode only in the far field, where the

Arc and resistance welding and tumours of the endocrine glands: a Swedish case-control study with focus on extremely low frequency magnetic fields.

PubMed

Håkansson, N; Stenlund, C; Gustavsson, P; Johansen, C; Floderus, B

2005-05-01

Mechanisms for potential effects of extremely low frequency (ELF) magnetic fields on carcinogenesis have not been identified. A potential pathway could be an interaction with the endocrine system. To analyse occupational exposure to ELF magnetic fields from welding, and tumours of the endocrine glands. This case-control study was based on a cohort with an increased prevalence of high exposed individuals. A total of 174 incident cases of tumours of the endocrine glands, 1985-94, were identified and data were obtained from 140 (80%) of these cases; 1692 controls frequency matched on sex and age were selected, and information on 1306 (77%) individuals was obtained. A short questionnaire was sent to a work administrator at the workplaces of the cases and controls. The exposure assessment was based on questions about job tasks, exposure to different types of welding, and exposure to solvents. There was an overall increased risk for all tumours of the endocrine glands for individuals who had been welding sometime during the follow up. The increased risk was attributable to arc welding; for resistance welding there was no clear evidence of an association. We found an increased risk for the adrenal glands in relation to arc welding, and for the parathyroid glands in relation to both arc welding and resistance welding. An imprecise increase in risk was also noted for tumours of the pituitary gland for arc welding. No confounding effect was found for solvent exposure, and there was no sign of biological interaction. The increased risks of endocrine gland tumours related to welding might be explained by exposure to high levels of ELF magnetic fields.

Arc and resistance welding and tumours of the endocrine glands: a Swedish case-control study with focus on extremely low frequency magnetic fields

PubMed Central

Hakansson, N; Stenlund, C; Gustavsson, P; Johansen, C; Floderus, B

2005-01-01

Background: Mechanisms for potential effects of extremely low frequency (ELF) magnetic fields on carcinogenesis have not been identified. A potential pathway could be an interaction with the endocrine system. Aims: To analyse occupational exposure to ELF magnetic fields from welding, and tumours of the endocrine glands. Methods: This case-control study was based on a cohort with an increased prevalence of high exposed individuals. A total of 174 incident cases of tumours of the endocrine glands, 1985–94, were identified and data were obtained from 140 (80%) of these cases; 1692 controls frequency matched on sex and age were selected, and information on 1306 (77%) individuals was obtained. A short questionnaire was sent to a work administrator at the workplaces of the cases and controls. The exposure assessment was based on questions about job tasks, exposure to different types of welding, and exposure to solvents. Results: There was an overall increased risk for all tumours of the endocrine glands for individuals who had been welding sometime during the follow up. The increased risk was attributable to arc welding; for resistance welding there was no clear evidence of an association. We found an increased risk for the adrenal glands in relation to arc welding, and for the parathyroid glands in relation to both arc welding and resistance welding. An imprecise increase in risk was also noted for tumours of the pituitary gland for arc welding. No confounding effect was found for solvent exposure, and there was no sign of biological interaction. Conclusion: The increased risks of endocrine gland tumours related to welding might be explained by exposure to high levels of ELF magnetic fields. PMID:15837851

Bare Quantum Null Energy Condition.

PubMed

Fu, Zicao; Marolf, Donald

2018-02-16

The quantum null energy condition (QNEC) is a conjectured relation between a null version of quantum field theory energy and derivatives of quantum field theory von Neumann entropy. In some cases, divergences cancel between these two terms and the QNEC is intrinsically finite. We study the more general case here where they do not and argue that a QNEC can still hold for bare (unrenormalized) quantities. While the original QNEC applied only to locally stationary null congruences in backgrounds that solve semiclassical theories of quantum gravity, at least in the formal perturbation theory at a small Planck length, the quantum focusing conjecture can be viewed as the special case of our bare QNEC for which the metric is on shell.

Bare Quantum Null Energy Condition

NASA Astrophysics Data System (ADS)

Fu, Zicao; Marolf, Donald

2018-02-01

The quantum null energy condition (QNEC) is a conjectured relation between a null version of quantum field theory energy and derivatives of quantum field theory von Neumann entropy. In some cases, divergences cancel between these two terms and the QNEC is intrinsically finite. We study the more general case here where they do not and argue that a QNEC can still hold for bare (unrenormalized) quantities. While the original QNEC applied only to locally stationary null congruences in backgrounds that solve semiclassical theories of quantum gravity, at least in the formal perturbation theory at a small Planck length, the quantum focusing conjecture can be viewed as the special case of our bare QNEC for which the metric is on shell.

All-sky photogrammetry techniques to georeference a cloud field

NASA Astrophysics Data System (ADS)

Crispel, Pierre; Roberts, Gregory

2018-01-01

In this study, we present a novel method of identifying and geolocalizing cloud field elements from a portable all-sky camera stereo network based on the ground and oriented towards zenith. The methodology is mainly based on stereophotogrammetry which is a 3-D reconstruction technique based on triangulation from corresponding stereo pixels in rectified images. In cases where clouds are horizontally separated, identifying individual positions is performed with segmentation techniques based on hue filtering and contour detection algorithms. Macroscopic cloud field characteristics such as cloud layer base heights and velocity fields are also deduced. In addition, the methodology is fitted to the context of measurement campaigns which impose simplicity of implementation, auto-calibration, and portability. Camera internal geometry models are achieved a priori in the laboratory and validated to ensure a certain accuracy in the peripheral parts of the all-sky image. Then, stereophotogrammetry with dense 3-D reconstruction is applied with cameras spaced 150 m apart for two validation cases. The first validation case is carried out with cumulus clouds having a cloud base height at 1500 m a.g.l. The second validation case is carried out with two cloud layers: a cumulus fractus layer with a base height at 1000 m a.g.l. and an altocumulus stratiformis layer with a base height of 2300 m a.g.l. Velocity fields at cloud base are computed by tracking image rectangular patterns through successive shots. The height uncertainty is estimated by comparison with a Vaisala CL31 ceilometer located on the site. The uncertainty on the horizontal coordinates and on the velocity field are theoretically quantified by using the experimental uncertainties of the cloud base height and camera orientation. In the first cumulus case, segmentation of the image is performed to identify individuals clouds in the cloud field and determine the horizontal positions of the cloud centers.

The Higgs boson can delay reheating after inflation

NASA Astrophysics Data System (ADS)

Freese, Katherine; Sfakianakis, Evangelos I.; Stengel, Patrick; Visinelli, Luca

2018-05-01

The Standard Model Higgs boson, which has previously been shown to develop an effective vacuum expectation value during inflation, can give rise to large particle masses during inflation and reheating, leading to temporary blocking of the reheating process and a lower reheat temperature after inflation. We study the effects on the multiple stages of reheating: resonant particle production (preheating) as well as perturbative decays from coherent oscillations of the inflaton field. Specifically, we study both the cases of the inflaton coupling to Standard Model fermions through Yukawa interactions as well as to Abelian gauge fields through a Chern-Simons term. We find that, in the case of perturbative inflaton decay to SM fermions, reheating can be delayed due to Higgs blocking and the reheat temperature can decrease by up to an order of magnitude. In the case of gauge-reheating, Higgs-generated masses of the gauge fields can suppress preheating even for large inflaton-gauge couplings. In extreme cases, preheating can be shut down completely and must be substituted by perturbative decay as the dominant reheating channel. Finally, we discuss the distribution of reheat temperatures in different Hubble patches, arising from the stochastic nature of the Higgs VEV during inflation and its implications for the generation of both adiabatic and isocurvature fluctuations.

[Syphilitic pleuritis. Description of a clinical case].

PubMed

Cattini, G C; Greco, N; Tosto, L; Falcieri, E; Biagini, G

1983-02-25

A rare case of luetic pleurisy diagnosed in a patient with tertiary syphilis, when the aetiological agent was discovered in the pleuritic exudate is described. The spirochaetes, first revealed by dark field microscopy, were studied further under the electron microscope, using negative colouring and fine sections.

How to locate and appraise qualitative research in complementary and alternative medicine

PubMed Central

2013-01-01

Background The aim of this publication is to present a case study of how to locate and appraise qualitative studies for the conduct of a meta-ethnography in the field of complementary and alternative medicine (CAM). CAM is commonly associated with individualized medicine. However, one established scientific approach to the individual, qualitative research, thus far has been explicitly used very rarely. This article demonstrates a case example of how qualitative research in the field of CAM studies was identified and critically appraised. Methods Several search terms and techniques were tested for the identification and appraisal of qualitative CAM research in the conduct of a meta-ethnography. Sixty-seven electronic databases were searched for the identification of qualitative CAM trials, including CAM databases, nursing, nutrition, psychological, social, medical databases, the Cochrane Library and DIMDI. Results 9578 citations were screened, 223 articles met the pre-specified inclusion criteria, 63 full text publications were reviewed, 38 articles were appraised qualitatively and 30 articles were included. The search began with PubMed, yielding 87% of the included publications of all databases with few additional relevant findings in the specific databases. CINHAL and DIMDI also revealed a high number of precise hits. Although CAMbase and CAM-QUEST® focus on CAM research only, almost no hits of qualitative trials were found there. Searching with broad text terms was the most effective search strategy in all databases. Conclusions This publication presents a case study on how to locate and appraise qualitative studies in the field of CAM. The example shows that the literature search for qualitative studies in the field of CAM is most effective when the search is begun in PubMed followed by CINHAL or DIMDI using broad text terms. Exclusive CAM databases delivered no additional findings to locate qualitative CAM studies. PMID:23731997

How to locate and appraise qualitative research in complementary and alternative medicine.

PubMed

Franzel, Brigitte; Schwiegershausen, Martina; Heusser, Peter; Berger, Bettina

2013-06-03

The aim of this publication is to present a case study of how to locate and appraise qualitative studies for the conduct of a meta-ethnography in the field of complementary and alternative medicine (CAM). CAM is commonly associated with individualized medicine. However, one established scientific approach to the individual, qualitative research, thus far has been explicitly used very rarely. This article demonstrates a case example of how qualitative research in the field of CAM studies was identified and critically appraised. Several search terms and techniques were tested for the identification and appraisal of qualitative CAM research in the conduct of a meta-ethnography. Sixty-seven electronic databases were searched for the identification of qualitative CAM trials, including CAM databases, nursing, nutrition, psychological, social, medical databases, the Cochrane Library and DIMDI. 9578 citations were screened, 223 articles met the pre-specified inclusion criteria, 63 full text publications were reviewed, 38 articles were appraised qualitatively and 30 articles were included. The search began with PubMed, yielding 87% of the included publications of all databases with few additional relevant findings in the specific databases. CINHAL and DIMDI also revealed a high number of precise hits. Although CAMbase and CAM-QUEST® focus on CAM research only, almost no hits of qualitative trials were found there. Searching with broad text terms was the most effective search strategy in all databases. This publication presents a case study on how to locate and appraise qualitative studies in the field of CAM. The example shows that the literature search for qualitative studies in the field of CAM is most effective when the search is begun in PubMed followed by CINHAL or DIMDI using broad text terms. Exclusive CAM databases delivered no additional findings to locate qualitative CAM studies.

Yellow Fever outbreak in Darfur, Sudan in October 2012; the initial outbreak investigation report.

PubMed

Soghaier, Mohammed A; Hagar, Ahmed; Abbas, Mohammed A; Elmangory, Mutasim M; Eltahir, Khalid M; Sall, Amadou A

2013-10-01

Sudan is subject to repeated outbreaks, including Viral Hemorrhagic Fever (VHF), which is considered to be a very serious illness. Yellow Fever (YF) outbreaks in Sudan have been reported from the 1940s through 2005. In 2012, a new outbreak of YF occurred in the Darfur region. To identify the potential for an outbreak, to diagnose the disease and to be able to recognize its cause among the initial reported cases. >This is a descriptive and investigative field study that applies standard communicable disease outbreak investigation steps. The study involved clinical, serological, entomological and environmental surveys. The field investigation confirmed the outbreak and identified its cause to be YF. National surveillance systems should be strong enough to detect VHFs in a timely manner. Local health facilities should be prepared to promptly treat the initial cases because the case fatality ratios (CFRs) are usually very high among the index cases. Copyright © 2013 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

Field-scale and wellbore modeling of compaction-induced casing failures

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

Hilbert, L.B. Jr.; Gwinn, R.L.; Moroney, T.A.

1999-06-01

Presented in this paper are the results and verification of field- and wellbore-scale large deformation, elasto-plastic, geomechanical finite element models of reservoir compaction and associated casing damage. The models were developed as part of a multidisciplinary team project to reduce the number of costly well failures in the diatomite reservoir of the South Belridge Field near Bakersfield, California. Reservoir compaction of high porosity diatomite rock induces localized shearing deformations on horizontal weak-rock layers and geologic unconformities. The localized shearing deformations result in casing damage or failure. Two-dimensional, field-scale finite element models were used to develop relationships between field operations, surfacemore » subsidence, and shear-induced casing damage. Pore pressures were computed for eighteen years of simulated production and water injection, using a three-dimensional reservoir simulator. The pore pressures were input to the two-dimensional geomechanical field-scale model. Frictional contact surfaces were used to model localized shear deformations. To capture the complex casing-cement-rock interaction that governs casing damage and failure, three-dimensional models of a wellbore were constructed, including a frictional sliding surface to model localized shear deformation. Calculations were compared to field data for verification of the models.« less

Characterizing AISI 1045 steel surface duplex-treated by alternating current field enhanced pack aluminizing and nitriding

NASA Astrophysics Data System (ADS)

Xie, Fei; Zhang, Ge; Pan, Jianwei

2018-02-01

Thin cases and long treating time are shortcomings of conventional duplex treatment of aluminizing followed by nitriding (DTAN). Alternating current field (ACF) enhanced DTAN was carried out on AISI 1045 steel by applying an ACF to treated samples and treating agents with a pair of electrodes for overcoming those shortcomings. By investigating cases' structures, phases, composition and hardness distributions of differently treated samples, preliminary studies were made on characterizations of the ACF enhanced duplex treatment to AISI 1045 steel. The results show that, with the help of the ACF, the surface Al-rich phase Al5Fe2 formed in conventional pack aluminizing can be easily avoided and the aluminizing process is dramatically promoted. The aluminizing case can be nitrided either with conventional pack nitriding or ACF enhanced pack nitriding. By applying ACF to pack nitriding, the diffusion of nitrogen into the aluminizing case is promoted. AlN, Fe2∼3N and solid solution of N in iron are efficiently formed as a result of reactions of N with the aluminizing case. A duplex treated case with an effective thickness of more than 170 μm can be obtained by the alternating current field enhanced 4 h pack aluminizing plus 4 h pack nitriding.

Interplanetary Magnetic Flux Ropes as Agents Connecting Solar Eruptions and Geomagnetic Activities

NASA Astrophysics Data System (ADS)

Marubashi, K.; Cho, K.-S.; Ishibashi, H.

2017-12-01

We investigate the solar wind structure for 11 cases that were selected for the campaign study promoted by the International Study of Earth-affecting Solar Transients (ISEST) MiniMax24 Working Group 4. We can identify clear flux rope signatures in nine cases. The geometries of the nine interplanetary magnetic flux ropes (IFRs) are examined with a model-fitting analysis with cylindrical and toroidal force-free flux rope models. For seven cases in which magnetic fields in the solar source regions were observed, we compare the IFR geometries with magnetic structures in their solar source regions. As a result, we can confirm the coincidence between the IFR orientation and the orientation of the magnetic polarity inversion line (PIL) for six cases, as well as the so-called helicity rule as regards the handedness of the magnetic chirality of the IFR, depending on which hemisphere of the Sun the IFR originated from, the northern or southern hemisphere; namely, the IFR has right-handed (left-handed) magnetic chirality when it is formed in the southern (northern) hemisphere of the Sun. The relationship between the orientation of IFRs and PILs can be taken as evidence that the flux rope structure created in the corona is in most cases carried through interplanetary space with its orientation maintained. In order to predict magnetic field variations on Earth from observations of solar eruptions, further studies are needed about the propagation of IFRs because magnetic fields observed at Earth significantly change depending on which part of the IFR hits the Earth.

Not all Laminaria digitata are the same! Phenotypic plasticity and the selection of appropriate surrogate macroalgae for ecohydraulic experimentation

NASA Astrophysics Data System (ADS)

Thomas, Robert E.; McLelland, Stuart J.; Henry, Pierre-Yves T.; Paul, Maike; Eiff, Olivier; Evertsen, Antti-Jussi O.; Aberle, Jochen; Teacă, Adrian

2015-04-01

Whilst early physical modelling and theoretical studies of the interactions between vegetation and flowing water employed rigid structures such as wooden dowels, recent studies have progressed to flexible surrogate plants. However, even appropriately-scaled flexible surrogates fail to capture the variability in thallus morphology, flexibility and strength, both within and between individuals, and frontal or planform area over space and time. Furthermore, although there have been a number of field studies, measurements of hydraulic variables have generally been limited to time-averaged at-a-point measurements that aim to approximate the depth-mean velocity. This is problematic because in spatially heterogeneous flows, point measurements are dependent upon the sampling location. Herein, we describe research carried out by the participants in the PISCES work package of the HYDRALAB IV project that sought to address these limitations and assess the level of complexity needed to adequately reproduce the hydrodynamics of the natural system in physical models. We selected an 11 m long × 6 m wide region of a tidal inlet, the Hopavågen Bay, Sør-Trøndelag, Norway, that contained 19 Laminaria digitata thalli and 101 other macroalgae thalli. Two L. digitata specimens ~0.50 m apart were selected for detailed study and a 2 m long × 8 m wide frame was oriented around them by enforcing zero cross-stream discharge at its upstream edge. We then quantified: 1. the mean and turbulent flow field of the undisturbed condition (Case A); 2. the positions, geometrical and biomechanical properties of the macroalgae; and 3. the mean and turbulent flow field after the macroalgae were completely removed (Case B). Later, Case A was replicated in the same location (±0.025 m) before the 19 L. digitata thalli were replaced with 19 "optimized" surrogates (Case C). These three cases were then repeated in the Total Environment Simulator at the University of Hull, UK. Live macroalgae thalli could not be transported from Norway to the UK, so we used the same species of live macroalgae harvested from a wave-dominated coast in the UK. These algae exhibited longer, narrower and more flexible blades. The same surrogate plants were used in both the field and flume experiments. In all cases, a profiling ADV was used to collect 45 velocity profiles composed of up to seven 35 mm-high profiles collected for 240 s at 100 Hz, at a streamwise spacing of 0.25 m and cross-stream spacing of 0.20 m. The results show that the live macroalgae in the flume simulation exerted less influence on the flow field than the live macroalgae at the field site. In contrast, the "optimized" surrogate macroalgae behaved similarly to the live algae at the field site and yielded similar mean and turbulent velocity fields as our prototype live macroalgae. This emphasizes both the importance of phenotypic plasticity and the importance of selecting surrogates that adequately represent the mean characteristics of the species of interest.

Analytical approximation schemes for solving exact renormalization group equations in the local potential approximation

NASA Astrophysics Data System (ADS)

Bervillier, C.; Boisseau, B.; Giacomini, H.

2008-02-01

The relation between the Wilson-Polchinski and the Litim optimized ERGEs in the local potential approximation is studied with high accuracy using two different analytical approaches based on a field expansion: a recently proposed genuine analytical approximation scheme to two-point boundary value problems of ordinary differential equations, and a new one based on approximating the solution by generalized hypergeometric functions. A comparison with the numerical results obtained with the shooting method is made. A similar accuracy is reached in each case. Both two methods appear to be more efficient than the usual field expansions frequently used in the current studies of ERGEs (in particular for the Wilson-Polchinski case in the study of which they fail).

Microwave resonant and zero-field absorption study of doped magnetite prepared by a co-precipitation method.

PubMed

Aphesteguy, Juan Carlos; Jacobo, Silvia E; Lezama, Luis; Kurlyandskaya, Galina V; Schegoleva, Nina N

2014-06-19

Fe3O4 and ZnxFe3-xO4 pure and doped magnetite magnetic nanoparticles (NPs) were prepared in aqueous solution (Series A) or in a water-ethyl alcohol mixture (Series B) by the co-precipitation method. Only one ferromagnetic resonance line was observed in all cases under consideration indicating that the materials are magnetically uniform. The shortfall in the resonance fields from 3.27 kOe (for the frequency of 9.5 GHz) expected for spheres can be understood taking into account the dipolar forces, magnetoelasticity, or magnetocrystalline anisotropy. All samples show non-zero low field absorption. For Series A samples the grain size decreases with an increase of the Zn content. In this case zero field absorption does not correlate with the changes of the grain size. For Series B samples the grain size and zero field absorption behavior correlate with each other. The highest zero-field absorption corresponded to 0.2 zinc concentration in both A and B series. High zero-field absorption of Fe3O4 ferrite magnetic NPs can be interesting for biomedical applications.

Parametric resonance in quantum electrodynamics vacuum birefringence

NASA Astrophysics Data System (ADS)

Arza, Ariel; Elias, Ricardo Gabriel

2018-05-01

Vacuum magnetic birefringence is one of the most interesting nonlinear phenomena in quantum electrodynamics because it is a pure photon-photon result of the theory and it directly signalizes the violation of the classical superposition principle of electromagnetic fields in the full quantum theory. We perform analytical and numerical calculations when an electromagnetic wave interacts with an oscillating external magnetic field. We find that in an ideal cavity, when the external field frequency is around the electromagnetic wave frequency, the normal and parallel components of the wave suffer parametric resonance at different rates, producing a vacuum birefringence effect growing in time. We also study the case where there is no cavity and the oscillating magnetic field is spatially localized in a region of length L . In both cases we find also a rotation of the elliptical axis.

Critical behavior of the spin-1 and spin-3/2 Baxter-Wu model in a crystal field.

PubMed

Dias, D A; Xavier, J C; Plascak, J A

2017-01-01

The phase diagram and the critical behavior of the spin-1 and the spin-3/2 two-dimensional Baxter-Wu model in a crystal field are studied by conventional finite-size scaling and conformal invariance theory. The phase diagram of this model, for the spin-1 case, is qualitatively the same as those of the diluted 4-states Potts model and the spin-1 Blume-Capel model. However, for the present case, instead of a tricritical point one has a pentacritical point for a finite value of the crystal field, in disagreement with previous work based on finite-size calculations. On the other hand, for the spin-3/2 case, the phase diagram is much richer and can present, besides a pentacritical point, an additional multicritical end point. Our results also support that the universality class of the critical behavior of the spin-1 and spin-3/2 Baxter-Wu model in a crystal field is the same as the pure Baxter-Wu model, even at the multicritical points.

Criteria for disintegration of an uncharged conducting liquid jet in a transverse electric field

NASA Astrophysics Data System (ADS)

Zubareva, O. V.; Zubarev, N. M.; Volkov, N. B.

2018-01-01

An uncharged conducting liquid cylindrical column (a jet for applications) placed between a pair of flat electrodes is considered. In the trivial case, when the electric field is absent, the jet with circular cross-section is the only possible equilibrium configuration of the system. In the presence of a potential difference between the electrodes, the jet is deformed by the electrostatic forces: its cross-section stretches along the electric field lines. In the case of the mutual compensation of the electrostatic and capillary forces, a new equilibrium configuration of the jet can appear. In a sufficiently strong field, the balance of the forces becomes impossible, and the jet disintegrates (splits into two separate jets). In the present work, we find the range of the parameters (the applied potential difference and the interelectrode distance), where the problem of finding the equilibrium configurations of the jet has solutions. Also we obtain the conditions under which the solutions do not exist and, consequently, the jet splits. The results are compared with the previously studied limiting case of infinite interelectrode distance.

Retrospective review of 50 canine nasal tumours evaluated by low-field magnetic resonance imaging.

PubMed

Avner, A; Dobson, J M; Sales, J I; Herrtage, M E

2008-05-01

Low-field magnetic resonance imaging machines are being used more often in veterinary practice for the investigation of sinonasal disease. The aim of this retrospective study was to describe and characterise the low-field magnetic resonance imaging features of nasal tumours in dogs. The Queen's Veterinary School Hospital magnetic resonance imaging database (2001-2005) was searched for dogs with a magnetic resonance imaging diagnosis of a nasal tumour. Fifty cases with histological diagnosis of nasal tumour were found. The appearance and extent of the nasal tumour as well as the involvement of adjacent anatomic structures were examined against a checklist. The most common magnetic resonance imaging findings were as follows. (1) Soft tissue mass replacing the destroyed nasal conchae and/or ethmoturbinates (98 per cent of cases). (2) Nasal septum destruction (68 per cent of cases). (3) Retained secretions with or without mass caudally in frontal sinuses (62 per cent of cases). (4) Nasal/frontal bone destruction (52 per cent of cases). Low-field magnetic resonance imaging allowed differentiation of tumour tissue from retained secretions or necrotic tissue. Magnetic resonance imaging was invaluable in assessing the extension of the tumour into the maxillary recesses, caudal recesses, nasopharynx, adjacent bones and cranial cavity. The tumour often extended caudally into the frontal sinuses, nasopharynx and perhaps most importantly into the caudal recesses. Tumour extension into the cranial cavity was not common (16 per cent), and only three of these cases showed neurological signs. However, 54 per cent of cases showed focal meningeal (dural) hyperintensity, although the significance of this is unclear. A significant difference (P<0.05) in tumour signal intensity between the sarcomas and carcinomas was found. The use of a low-field magnetic resonance imaging technique is excellent for the diagnosis and determination of extent of sinonasal tumours.

Effect of the magnetic field on the supramolecular structure of chiral smectic C phases: (2)H NMR studies.

PubMed

Domenici, Valentina; Marini, Alberto; Veracini, Carlo Alberto; Zhang, Jing; Dong, Ronald Y

2007-12-21

We present a theoretical and experimental (2)H NMR study of the effect of external magnetic fields on the supramolecular organization of chiral smectic liquid-crystalline mesophases, such as SmC* and re-entrant SmC*. Three experimental cases in which the supramolecular helical structure of the smectic C* phase is unwound by a magnetic field (H), parallel to the helical axes of this phase, are discussed in detail. Unwinding of the helical structure is described by using a theoretical model based on the Landau-de Gennes theory, which allows us to explain the transition temperatures among the SmA, SmC*, and uSmC* phases. The energy-density behavior in the vicinity of the transitions and the value of the critical magnetic field H(C) for unwinding the helical structure are discussed by applying this model to three ferroelectric smectogens (MBHB, 11EB1M7, ZLL7/*), which are studied by (2)H NMR spectroscopy at different magnetic fields (from 2.4 to 9.4 Tesla). Furthermore, the tilt angle of the three smectogens in the SmC* phase has been directly evaluated, for the first time, by comparing the quadrupolar splittings at different magnetic fields. In one case, (2)H NMR angular measurements are used to obtain the tilt angle in the re-entrant smectic C phase.

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…

Book review: old fields: dynamics and restoration of abandoned farmland

USDA-ARS?s Scientific Manuscript database

The 2007 volume, “Old Fields: Dynamics and Restoration of Abandoned Farmland”, edited by VA Cramer and RJ Hobbs and published by the Society for Ecological Restoration International (Island Press), is a valuable attempt to synthesize a dozen case studies on agricultural abandonment from all of the ...

Wormhole solutions with a complex ghost scalar field and their instability

NASA Astrophysics Data System (ADS)

Dzhunushaliev, Vladimir; Folomeev, Vladimir; Kleihaus, Burkhard; Kunz, Jutta

2018-01-01

We study compact configurations with a nontrivial wormholelike spacetime topology supported by a complex ghost scalar field with a quartic self-interaction. For this case, we obtain regular asymptotically flat equilibrium solutions possessing reflection symmetry. We then show their instability with respect to linear radial perturbations.

Detection of Infectious Bovine Rhinotracheitis and Bovine Viral Diarrhea Viruses in the Nasal Epithelial Cells by the Direct Immunofluorescence Technique

PubMed Central

Silim, A.; Elazhary, M.A.S.Y.

1983-01-01

Nasal epithelial cells were collected by cotton swabs for the diagnosis in experimental and field cases of infectious bovine rhinotracheitis and field cases of bovine viral diarrhea in calves. A portion of the cells was washed twice in phosphate buffered saline and a 25 µL drop was placed on microscope slides. The cells were dried, fixed and stained according to the direct fluorescent antibody technique. Another portion of the same specimen was inoculated onto primary bovine skin cell cultures for virus isolation. In the experimental studies for infectious bovine rhinotracheitis, 29/35 specimens were positive by fluorescent antibody technique and 32/35 by cell culture and in the field cases, 22/119 were positive by fluorescent antibody technique and 19/119 by cell culture. In the field cases of bovine viral diarrhea, 28/69 samples were positive by fluorescent antibody technique and 14/69 by cell culture. When fluorescent antibody technique was performed on inoculated cell cultures a total of 24/69 specimens were positive for bovine viral diarrhea. The sensitivity of fluorescent antibody technique was thus comparable to that of cell culture method for infectious bovine rhinotracheitis and bovine viral diarrhea. ImagesFig. 1.Fig. 2.Fig. 3. PMID:6299484

The logarithmic Cardy case: Boundary states and annuli

NASA Astrophysics Data System (ADS)

Fuchs, Jürgen; Gannon, Terry; Schaumann, Gregor; Schweigert, Christoph

2018-05-01

We present a model-independent study of boundary states in the Cardy case that covers all conformal field theories for which the representation category of the chiral algebra is a - not necessarily semisimple - modular tensor category. This class, which we call finite CFTs, includes all rational theories, but goes much beyond these, and in particular comprises many logarithmic conformal field theories. We show that the following two postulates for a Cardy case are compatible beyond rational CFT and lead to a universal description of boundary states that realizes a standard mathematical setup: First, for bulk fields, the pairing of left and right movers is given by (a coend involving) charge conjugation; and second, the boundary conditions are given by the objects of the category of chiral data. For rational theories our proposal reproduces the familiar result for the boundary states of the Cardy case. Further, with the help of sewing we compute annulus amplitudes. Our results show in particular that these possess an interpretation as partition functions, a constraint that for generic finite CFTs is much more restrictive than for rational ones.

STEMujeres: A case study of the life stories of first-generation Latina engineers and scientists

NASA Astrophysics Data System (ADS)

Vielma, Karina I.

Research points to the many obstacles that first-generation, Latina students face when attempting to enter fields in science, technology, engineering, and mathematics, STEM. This qualitative, case study examined the personal and educational experiences of first-generation Latina women who successfully navigated the STEM educational pipeline earning bachelor's, master's, and doctoral degrees in various fields of engineering. Three research questions guided the study: (1) How does a first-generation Latina engineer and scientist describe her life experiences as she became interested in STEM? (2) How does she describe her educational experiences as she navigated the educational pipeline in the physics, mathematics, and/or engineering field(s)? (3) How did she respond to challenges, obstacles and microaggressions, if any, while navigating the STEM educational pipeline? The study was designed using a combination of Critical Race Theory frameworks---Chicana feminist theory and racial microaggressions. Through a life history case study approach, the women shared their stories of success. With the participants' help, influential persons in their educational paths were identified and interviewed. Data were analyzed using crystallization and thematic results indicated that all women in this study identified their parents as planting the seed of interest through the introduction of mathematics. The women unknowingly prepared to enter the STEM fields by taking math and science coursework. They were guided to apply to STEM universities and academic programs by others who knew about their interest in math and science including teachers, counselors, and level-up peers---students close in age who were just a step more advanced in the educational pipeline. The women also drew from previous familial struggles to guide their perseverance and motivation toward educational degree completion. The lives of the women where complex and intersected with various forms of racism including gender, race, class, legality and power. In many instances, the women used their knowledge to help other STEMujeres advance.

Using Peer Reviews to Examine Micropolitics and Disciplinary Development of Engineering Education: A Case Study

ERIC Educational Resources Information Center

Beddoes, Kacey

2014-01-01

This article presents a case study of the peer review process for a feminist article submitted to an engineering education journal. It demonstrates how an examination of peer review can be a useful approach to further understanding the development of feminist thought in education fields. Rather than opposition to feminist thought per se, my…

Distribution of sediment measurements in Lake Michigan as a case study: Implications for estimating sediment and water interactions in eutrophication and bioaccumulation models

EPA Science Inventory

Lake Michigan, the sixth largest freshwater lake in the world by surface area, was utilized as a water body for assessment within a case study. Field data collected at 116 sampling sites throughout the lake in an intensive monitoring effort were utilized for evaluation of the di...

Beyond Clinical Case Studies in Psychoanalysis: A Review of Psychoanalytic Empirical Single Case Studies Published in ISI-Ranked Journals.

PubMed

Meganck, Reitske; Inslegers, Ruth; Krivzov, Juri; Notaerts, Liza

2017-01-01

Single case studies are at the origin of both theory development and research in the field of psychoanalysis and psychotherapy. While clinical case studies are the hallmark of psychoanalytic theory and practice, their scientific value has been strongly criticized. To address problems with the subjective bias of retrospective therapist reports and uncontrollability of clinical case studies, systematic approaches to investigate psychotherapy process and outcome at the level of the single case have been developed. Such empirical case studies are also able to bridge the famous gap between academic research and clinical practice as they provide clinically relevant insights into how psychotherapy works. This study presents a review of psychoanalytic empirical case studies published in ISI-ranked journals and maps the characteristics of the study, therapist, patient en therapies that are investigated. Empirical case studies increased in quantity and quality (amount of information and systematization) over time. While future studies could pay more attention to providing contextual information on therapist characteristics and informed consent considerations, the available literature provides a basis to conduct meta-studies of single cases and as such contribute to knowledge aggregation.

Prolepsis, Syncretism, and Synergy in Early Language and Literacy Practices: A Case Study of Family Language Policy in Singapore

ERIC Educational Resources Information Center

Ren, Li; Hu, Guangwei

2013-01-01

This article reports a case study of two Chinese-English bilingual families in Singapore and illustrates the importance of incorporating two hitherto disconnected fields of research--family language policy and family literacy practices--to an understanding of early language and literacy acquisition in the familial milieu. Specifically, this work…

A Pedagogical Trebuchet: A Case Study in Experimental History and History Pedagogy

ERIC Educational Resources Information Center

Brice, Lee L.; Catania, Steven

2012-01-01

A common problem history teachers face regardless of their field of specialization is how to help students find answers to the most difficult historical questions, those for which the sources are unavailable or inaccessible, and teach them to do so in a methodologically valid manner. This article presents a case study which shows how a project in…

Beyond Clinical Case Studies in Psychoanalysis: A Review of Psychoanalytic Empirical Single Case Studies Published in ISI-Ranked Journals

PubMed Central

Meganck, Reitske; Inslegers, Ruth; Krivzov, Juri; Notaerts, Liza

2017-01-01

Single case studies are at the origin of both theory development and research in the field of psychoanalysis and psychotherapy. While clinical case studies are the hallmark of psychoanalytic theory and practice, their scientific value has been strongly criticized. To address problems with the subjective bias of retrospective therapist reports and uncontrollability of clinical case studies, systematic approaches to investigate psychotherapy process and outcome at the level of the single case have been developed. Such empirical case studies are also able to bridge the famous gap between academic research and clinical practice as they provide clinically relevant insights into how psychotherapy works. This study presents a review of psychoanalytic empirical case studies published in ISI-ranked journals and maps the characteristics of the study, therapist, patient en therapies that are investigated. Empirical case studies increased in quantity and quality (amount of information and systematization) over time. While future studies could pay more attention to providing contextual information on therapist characteristics and informed consent considerations, the available literature provides a basis to conduct meta-studies of single cases and as such contribute to knowledge aggregation. PMID:29046660

A study: Effect of Students Peer Assisted Learning on Magnetic Field Achievement

NASA Astrophysics Data System (ADS)

Mueanploy, Wannapa

2016-04-01

This study is the case study of Physic II Course for students of Pathumwan Institute of Technology. The purpose of this study is: 1) to develop cooperative learning method of peer assisted learning (PAL), 2) to compare the learning achievement before and after studied magnetic field lesson by cooperative learning method of peer assisted learning. The population was engineering students of Pathumwan Institute of Technology (PIT’s students) who registered Physic II Course during year 2014. The sample used in this study was selected from the 72 students who passed in Physic I Course. The control groups learning magnetic fields by Traditional Method (TM) and experimental groups learning magnetic field by method of peers assisted learning. The students do pretest before the lesson and do post-test after the lesson by 20 items achievement tests of magnetic field. The post-test higher than pretest achievement significantly at 0.01 level.

The Influence of Hyperons and Strong Magnetic Field in Neutron Star Properties

NASA Astrophysics Data System (ADS)

Lopes, L. L.; Menezes, D. P.

2012-12-01

Neutron stars are among of the most exotic objects in the universe and constitute a unique laboratory to study nuclear matter above the nuclear saturation density. In this work, we study the equation of state (EoS) of the nuclear matter within a relativistic model subject to a strong magnetic field. We then apply this EoS to study and describe some of the physical characteristics of neutron stars, especially the mass-radius relation and chemical compositions. To study the influence of the magnetic field and the hyperons in the stellar interior, we consider altogether four solutions: two different magnetic field to obtain a weak and a strong influence; and two configurations: a family of neutron stars formed only by protons, electrons, and neutrons and a family formed by protons, electrons, neutrons, muons, and hyperons. The limit and the validity of the results found are discussed with some care. In all cases, the particles that constitute the neutron star are in β equilibrium and zero total net charge. Our work indicates that the effect of a strong magnetic field has to be taken into account in the description of magnetars, mainly if we believe that there are hyperons in their interior, in which case the influence of the magnetic field can increase the mass by more than 10 %. We have also seen that although a magnetar can reach 2.48 M ⊙, a natural explanation of why we do not know pulsars with masses above 2.0 M ⊙ arises. We also discuss how the magnetic field affects the strangeness fraction in some standard neutron star masses, and to conclude our paper, we revisit the direct Urca process related to the cooling of the neutron stars and show how it is affected by the hyperons and the magnetic field.

Investigating an outbreak of measles in Margibi County, Liberia, October 2015.

PubMed

Frimpong, Joseph Asamoah; Amo-Addae, Maame Pokuah; Adewuyi, Peter Adebayo; Park, Meeyoung Mattie; Hall, Casey Daniel; Nagbe, Thomas Knue

2017-01-01

The emergence and re-emergence of infectious diseases highlights the need to have well-trained field epidemiologists who will be at the forefront in the fight against these diseases, especially during an outbreak. Training for outbreak investigation is most effective when participants can develop their competencies in a practical exercise. To that end, this case study was based on a measles outbreak investigation conducted in Liberia during October 2015 by Liberia Frontline Field Epidemiology Training Program (FETP) residents, simulating steps to perform outbreak investigation in a real-life situation as a field epidemiologist. This case study is ideally suited to reinforce principles and skills already covered in a classroom lecture or in background reading by providing a practical training beyond the scope of theoretical learning. It is primarily intended for training novice public health practitioners who should be able to complete the exercises in approximately 3 hours.

Steady hydromagnetic flows in open magnetic fields. I - A class of analytic solutions. [for stellar winds

NASA Technical Reports Server (NTRS)

Low, B. C.; Tsinganos, K.

1986-01-01

In the case of an establishment of theoretical models of the hydromagnetic solar wind, the inclusion of the effects of the magnetic field in the solar wind makes it extremely dificult to solve the mathematical problem. This paper has the objective to present a set of particular analytic solutions. The general formulation of Tsinganos (1982) is used to identify a class of analytic solutions to the equations of steady hydromagnetic flows in spherical coordinates. Flow in an open magnetic field are studied, taking into account the problem in dimensionless form, the special case of radial flows with alpha = 0, general radial flows, illustrative examples for flows in which alpha is not equal to 0, a parametric study of nonradial flows in which alpha is not equal to zero, variations in the parameter nu, and variations in the initial speed eta.

Spectra of turbulently advected scalars that have small Schmidt number

NASA Astrophysics Data System (ADS)

Hill, Reginald J.

2017-09-01

Exact statistical equations are derived for turbulent advection of a passive scalar having diffusivity much larger than the kinematic viscosity, i.e., small Schmidt number. The equations contain all terms needed for precise direct numerical simulation (DNS) quantification. In the appropriate limit, the equations reduce to the classical theory for which the scalar spectrum is proportional to the energy spectrum multiplied by k-4, which, in turn, results in the inertial-diffusive range power law, k-17 /3. The classical theory was derived for the case of isotropic velocity and scalar fields. The exact equations are simplified for less restrictive cases: (1) locally isotropic scalar fluctuations at dissipation scales with no restriction on symmetry of the velocity field, (2) isotropic velocity field with averaging over all wave-vector directions with no restriction on the symmetry of the scalar, motivated by that average being used for DNS, and (3) isotropic velocity field with axisymmetric scalar fluctuations, motivated by the mean-scalar-gradient-source case. The equations are applied to recently published DNSs of passive scalars for the cases of a freely decaying scalar and a mean-scalar-gradient source. New terms in the exact equations are estimated for those cases and are found to be significant; those terms cause the deviations from the classical theory found by the DNS studies. A new formula for the mean-scalar-gradient case explains the variation of the scalar spectra for the DNS of the smallest Schmidt-number cases. Expansion in Legendre polynomials reveals the effect of axisymmetry. Inertial-diffusive-range formulas for both the zero- and second-order Legendre contributions are given. Exact statistical equations reveal what must be quantified using DNS to determine what causes deviations from asymptotic relationships.

From Science to e-Science to Semantic e-Science: A Heliosphysics Case Study

NASA Technical Reports Server (NTRS)

Narock, Thomas; Fox, Peter

2011-01-01

The past few years have witnessed unparalleled efforts to make scientific data web accessible. The Semantic Web has proven invaluable in this effort; however, much of the literature is devoted to system design, ontology creation, and trials and tribulations of current technologies. In order to fully develop the nascent field of Semantic e-Science we must also evaluate systems in real-world settings. We describe a case study within the field of Heliophysics and provide a comparison of the evolutionary stages of data discovery, from manual to semantically enable. We describe the socio-technical implications of moving toward automated and intelligent data discovery. In doing so, we highlight how this process enhances what is currently being done manually in various scientific disciplines. Our case study illustrates that Semantic e-Science is more than just semantic search. The integration of search with web services, relational databases, and other cyberinfrastructure is a central tenet of our case study and one that we believe has applicability as a generalized research area within Semantic e-Science. This case study illustrates a specific example of the benefits, and limitations, of semantically replicating data discovery. We show examples of significant reductions in time and effort enable by Semantic e-Science; yet, we argue that a "complete" solution requires integrating semantic search with other research areas such as data provenance and web services.

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.

Gathering system optimization in a gas field with commingled flowlines

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

Soetedja, V.; Harun, A.F.

1995-10-01

Badak Field, located in East Kalimantan, Indonesia, is a giant onshore gas field with 181 wells and total gas deliverability of 1.3 billion standard cubic feet (BSCF) per day. In many cases, gas from more than one well is commingled in the same flowline. This study concludes that commingling flowlines has been extremely cost effective over the life of the field. However, good initial design is required to anticipate future reservoir depletion and recompletions in order to achieve the best economic efficiency.

Video Capture of Plastic Surgery Procedures Using the GoPro HERO 3+.

PubMed

Graves, Steven Nicholas; Shenaq, Deana Saleh; Langerman, Alexander J; Song, David H

2015-02-01

Significant improvements can be made in recoding surgical procedures, particularly in capturing high-quality video recordings from the surgeons' point of view. This study examined the utility of the GoPro HERO 3+ Black Edition camera for high-definition, point-of-view recordings of plastic and reconstructive surgery. The GoPro HERO 3+ Black Edition camera was head-mounted on the surgeon and oriented to the surgeon's perspective using the GoPro App. The camera was used to record 4 cases: 2 fat graft procedures and 2 breast reconstructions. During cases 1-3, an assistant remotely controlled the GoPro via the GoPro App. For case 4 the GoPro was linked to a WiFi remote, and controlled by the surgeon. Camera settings for case 1 were as follows: 1080p video resolution; 48 fps; Protune mode on; wide field of view; 16:9 aspect ratio. The lighting contrast due to the overhead lights resulted in limited washout of the video image. Camera settings were adjusted for cases 2-4 to a narrow field of view, which enabled the camera's automatic white balance to better compensate for bright lights focused on the surgical field. Cases 2-4 captured video sufficient for teaching or presentation purposes. The GoPro HERO 3+ Black Edition camera enables high-quality, cost-effective video recording of plastic and reconstructive surgery procedures. When set to a narrow field of view and automatic white balance, the camera is able to sufficiently compensate for the contrasting light environment of the operating room and capture high-resolution, detailed video.

Schooling's "Contribution" to Contemporary Violent Conflict: Review of Theoretical Ideas and Case Studies in the Field of Education and Conflict

ERIC Educational Resources Information Center

Matsumoto, Mitsuko

2015-01-01

Some argue that the field of study of "education and conflict" has yet to be solidified since its emergence in the 1990s, partly due to the weak theory base. This article reviews the literature on the "contribution" of schooling in contemporary violent conflict, via three strands of theoretical ideas, to demonstrate the…

Supporting Collaborative Inquiry during a Biology Field Trip with Mobile Peer-to-Peer Tools for Learning: A Case Study with K-12 Learners

ERIC Educational Resources Information Center

Laru, Jari; Jarvela, Sanna; Clariana, Roy B.

2012-01-01

This study explores how collaborative inquiry learning can be supported with multiple scaffolding agents in a real-life field trip context. In practice, a mobile peer-to-peer messaging tool provided meta-cognitive and procedural support, while tutors and a nature guide provided more dynamic scaffolding in order to support argumentative discussions…

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

Ghosh, Shamik; Kothari, Rahul; Jain, Pankaj

We propose a dipole modulation model for the Cosmic Microwave Background Radiation (CMBR) polarization field. We show that the model leads to correlations between l and l+1 multipoles, exactly as in the case of temperature. We obtain results for the case of TE, EE and BB correlations. An anisotropic or inhomogeneous model of primordial power spectrum which leads to such correlations in temperature field also predicts similar correlations in CMBR polarization. We analyze the CMBR temperature and polarization data in order to extract the signal of these correlation between l and l+1 multipoles. Our results for the case of temperaturemore » using the latest PLANCK data agree with those obtained by an earlier analysis. A detailed study of the correlation in the polarization data is not possible at present. Hence we restrict ourselves to a preliminary investigation in this case.« less

Field quantization and squeezed states generation in resonators with time-dependent parameters

NASA Technical Reports Server (NTRS)

Dodonov, V. V.; Klimov, A. B.; Nikonov, D. E.

1992-01-01

The problem of electromagnetic field quantization is usually considered in textbooks under the assumption that the field occupies some empty box. The case when a nonuniform time-dependent dielectric medium is confined in some space region with time-dependent boundaries is studied. The basis of the subsequent consideration is the system of Maxwell's equations in linear passive time-dependent dielectric and magnetic medium without sources.

Analytical study of a Kerr-Sen black hole and a charged massive scalar field

NASA Astrophysics Data System (ADS)

Bernard, Canisius

2017-11-01

It is reported that Kerr-Newman and Kerr-Sen black holes are unstable to perturbations of charged massive scalar field. In this paper, we study analytically the complex frequencies which characterize charged massive scalar fields in a near-extremal Kerr-Sen black hole. For near-extremal Kerr-Sen black holes and for charged massive scalar fields in the eikonal large-mass M ≫μ regime, where M is the mass of the black hole, and μ is the mass of the charged scalar field, we have obtained a simple expression for the dimensionless ratio ωI/(ωR-ωc) , where ωI and ωR are, respectively, the imaginary and real parts of the frequency of the modes, and ωc is the critical frequency for the onset of super-radiance. We have also found our expression is consistent with the result of Hod [Phys. Rev. D 94, 044036 (2016), 10.1103/PhysRevD.94.044036] for the case of a near-extremal Kerr-Newman black hole and the result of Zouros and Eardly [Ann. Phys. (N.Y.) 118, 139 (1979), 10.1016/0003-4916(79)90237-9] for the case of neutral scalar fields in the background of a near-extremal Kerr black hole.

Robustness of inflation to inhomogeneous initial conditions

NASA Astrophysics Data System (ADS)

Clough, Katy; Lim, Eugene A.; DiNunno, Brandon S.; Fischler, Willy; Flauger, Raphael; Paban, Sonia

2017-09-01

We consider the effects of inhomogeneous initial conditions in both the scalar field profile and the extrinsic curvature on different inflationary models. In particular, we compare the robustness of small field inflation to that of large field inflation, using numerical simulations with Einstein gravity in 3+1 dimensions. We find that small field inflation can fail in the presence of subdominant gradient energies, suggesting that it is much less robust to inhomogeneities than large field inflation, which withstands dominant gradient energies. However, we also show that small field inflation can be successful even if some regions of spacetime start out in the region of the potential that does not support inflation. In the large field case, we confirm previous results that inflation is robust if the inflaton occupies the inflationary part of the potential. Furthermore, we show that increasing initial scalar gradients will not form sufficiently massive inflation-ending black holes if the initial hypersurface is approximately flat. Finally, we consider the large field case with a varying extrinsic curvature K, such that some regions are initially collapsing. We find that this may again lead to local black holes, but overall the spacetime remains inflationary if the spacetime is open, which confirms previous theoretical studies.

Klein-Gordon oscillator with position-dependent mass in the rotating cosmic string spacetime

NASA Astrophysics Data System (ADS)

Wang, Bing-Qian; Long, Zheng-Wen; Long, Chao-Yun; Wu, Shu-Rui

2018-02-01

A spinless particle coupled covariantly to a uniform magnetic field parallel to the string in the background of the rotating cosmic string is studied. The energy levels of the electrically charged particle subject to the Klein-Gordon oscillator are analyzed. Afterwards, we consider the case of the position-dependent mass and show how these energy levels depend on the parameters in the problem. Remarkably, it shows that for the special case, the Klein-Gordon oscillator coupled covariantly to a homogeneous magnetic field with the position-dependent mass in the rotating cosmic string background has the similar behaviors to the Klein-Gordon equation with a Coulomb-type configuration in a rotating cosmic string background in the presence of an external magnetic field.

Identification of Recombinant Human Rhinovirus A and C in Circulating Strains from Upper and Lower Respiratory Infections

PubMed Central

Kim, Hak; Kim, Kisoon; Kim, Dae-Won; Jung, Hee-Dong; Min Cheong, Hyang; Kim, Ki Hwan; Soo Kim, Dong; Kim, You-Jin

2013-01-01

Human rhinoviruses (HRVs), in the Enterovirus genus within the family Picornaviridae, are a highly prevalent cause of acute respiratory infection (ARI). Enteroviruses are genetically highly variable, and recombination between serotypes is known to be a major contribution to their diversity. Recently it was reported that recombination events in HRVs cause the diversity of HRV-C. This study analyzed parts of the viral genes spanning the 5′ non- coding region (NCR) through to the viral protein (VP) encoding sequences of 105 HRV field isolates from 51 outpatient cases of Acute Respiratory Infectious Network (ARINET) and 54 inpatient cases of severe lower respiratory infection (SLRI) surveillance, in order to identify recombination in field samples. When analyzing parts of the 5′NCR and VP4/VP2 encoding sequences, we found intra- and interspecies recombinants in field strains of HRV-A and -C. Nineteen cases of recombination events (18.1%) were found among 105 field strains. For HRV-A, there were five cases (4.8%) of intraspecies recombination events and three cases (2.8%) of interspecies recombination events. For HRV-C, there were four cases (3.8%) of intraspecies recombination events and seven cases (6.7%) of interspecies recombination events. Recombination events were significantly more frequently observed in the ARINET samples (18 cases) than in the SLRI samples (1 case; P< 0.0001). The recombination breakpoints were located in nucleotides (nt) 472–554, which comprise stem-loop 5 in the internal ribosomal entry site (IRES), based on the HRV-B 35 sequence (accession no. FJ445187). Our findings regarding genomic recombination in circulating HRV-A and -C strains suggest that recombination might play a role in HRV fitness and could be a possible determinant of disease severity caused by various HRV infections in patients with ARI. PMID:23826363

Magnetic suppression of turbulence and the star formation activity of molecular clouds

NASA Astrophysics Data System (ADS)

Zamora-Avilés, Manuel; Vázquez-Semadeni, Enrique; Körtgen, Bastian; Banerjee, Robi; Hartmann, Lee

2018-03-01

We present magnetohydrodynamic simulations aimed at studying the effect of the magnetic suppression of turbulence (generated through various instabilities during the formation of molecular clouds by converging) on the subsequent star formation (SF) activity. We study four magnetically supercritical models with magnetic field strengths B = 0, 1, 2, and 3 μG (corresponding to mass-to-flux ratios of ∞, 4.76, 2.38, and 1.59 times the critical value), with the magnetic field, initially being aligned with the flows. We find that, for increasing magnetic field strength, the clouds formed tend to be more massive, denser, less turbulent, and with higher SF activity. This causes the onset of SF activity in the non-magnetic or more weakly magnetized cases to be delayed by a few Myr in comparison to the more strongly magnetized cases. We attribute this behaviour to the suppression of the non-linear thin shell instability (NTSI) by the magnetic field, previously found by Heitsch and coworkers. This result is contrary to the standard notion that the magnetic field provides support to the clouds, thus reducing their star formation rate. However, our result is a completely non-linear one, and could not be foreseen from simple linear considerations.

Confluent Heun functions and the physics of black holes: Resonant frequencies, Hawking radiation and scattering of scalar waves

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

Vieira, H.S., E-mail: horacio.santana.vieira@hotmail.com; Centro de Ciências, Tecnologia e Saúde, Universidade Estadual da Paraíba, CEP 58233-000, Araruna, PB; Bezerra, V.B., E-mail: valdir@fisica.ufpb.br

We apply the confluent Heun functions to study the resonant frequencies (quasispectrum), the Hawking radiation and the scattering process of scalar waves, in a class of spacetimes, namely, the ones generated by a Kerr–Newman–Kasuya spacetime (dyon black hole) and a Reissner–Nordström black hole surrounded by a magnetic field (Ernst spacetime). In both spacetimes, the solutions for the angular and radial parts of the corresponding Klein–Gordon equations are obtained exactly, for massive and massless fields, respectively. The special cases of Kerr and Schwarzschild black holes are analyzed and the solutions obtained, as well as in the case of a Schwarzschild blackmore » hole surrounded by a magnetic field. In all these special situations, the resonant frequencies, Hawking radiation and scattering are studied. - Highlights: • Charged massive scalar field in the dyon black hole and massless scalar field in the Ernst spacetime are analyzed. • The confluent Heun functions are applied to obtain the solution of the Klein–Gordon equation. • The resonant frequencies are obtained. • The Hawking radiation and the scattering process of scalar waves are examined.« less

Electron acceleration by laser produced wake field: Pulse shape effect

NASA Astrophysics Data System (ADS)

Malik, Hitendra K.; Kumar, Sandeep; Nishida, Yasushi

2007-12-01

Analytical expressions are obtained for the longitudinal field (wake field: Ex), density perturbations ( ne') and the potential ( ϕ) behind a laser pulse propagating in a plasma with the pulse duration of the electron plasma period. A feasibility study on the wake field is carried out with Gaussian-like (GL) pulse, rectangular-triangular (RT) pulse and rectangular-Gaussian (RG) pulse considering one-dimensional weakly nonlinear theory ( ne'/n0≪1), and the maximum energy gain acquired by an electron is calculated for all these three types of the laser pulse shapes. A comparative study infers that the RT pulse yields the best results: In its case maximum electron energy gain is 33.5 MeV for a 30 fs pulse duration whereas in case of GL (RG) pulse of the same duration the gain is 28.6 (28.8)MeV at the laser frequency of 1.6 PHz and the intensity of 3.0 × 10 18 W/m 2. The field of the wake and hence the energy gain get enhanced for the higher laser frequency, larger pulse duration and higher laser intensity for all types of the pulses.

Operationally Comparable Effect Sizes for Quantifying Changes in Behavior, with Application to Meta-Analysis of Single-Case Studies

ERIC Educational Resources Information Center

Pustejovsky, James E.

2013-01-01

Single-case designs (SCDs) are a class of research methods for evaluating intervention effects by taking repeated measurements of an outcome over time on a single case, both before and after the deliberate introduction of a treatment. SCDs are used heavily in fields such as special education, school psychology, social work, and applied behavior…

Electrostatics in Stueckelberg-Horwitz electrodynamics

NASA Astrophysics Data System (ADS)

Land, Martin

2013-04-01

In this paper, we study fundamental aspects of electrostatics as a special case in Stueckelberg-Horwitz electromagnetic theory. In this theory, spacetime events xμ(τ) evolve in an unconstrained 8-dimensional phase space, interacting through five τ-dependent gauge fields induced by the current densities associated with their evolutions. The chronological time τ was introduced as an independent evolution parameter in order to free the laboratory clock x0 to evolve alternately 'forward' and 'backward' in time according to the sign of the energy, thus providing a classical implementation of the Feynman-Stueckelberg interpretation of pair creation/annihilation. The resulting theory differs in its underlying mechanics from conventional electromagnetism, but coincides with Maxwell theory in an equilibrium limit. After a brief review of Stueckelberg-Horwitz electrodynamics, we obtain the field produced by an event in uniform motion and verify that it satisfies the field equations. We study this field in the rest frame of the event, where it depends explicitly on coordinate time x0 and the parameter τ, as well as spatial distance R. Calculating with this generalized Coulomb field, we demonstrate how Gauss's theorem and Stoke's theorem apply in 4D spacetime, and obtain the fields associated with a charged line and a charged sheet. Finally, we use the field of the charged sheet to study a static event in the vicinity of a potential barrier. In all of these cases, we observe a small transfer of mass from the field to the particle. It is seen that for an event in the field of an oppositely charged sheet of sufficient density, the event can reverse time direction, providing a specific model for pair phenomena.

Effects of a parallel electric field and the geomagnetic field in the topside ionosphere on auroral and photoelectron energy distributions

NASA Technical Reports Server (NTRS)

Min, Q.-L.; Lummerzheim, D.; Rees, M. H.; Stamnes, K.

1993-01-01

The consequences of electric field acceleration and an inhomogeneous magnetic field on auroral electron energy distributions in the topside ionosphere are investigated. The one-dimensional, steady state electron transport equation includes elastic and inelastic collisions, an inhomogeneous magnetic field, and a field-aligned electric field. The case of a self-consistent polarization electric field is considered first. The self-consistent field is derived by solving the continuity equation for all ions of importance, including diffusion of O(+) and H(+), and the electron and ion energy equations to derive the electron and ion temperatures. The system of coupled electron transport, continuity, and energy equations is solved numerically. Recognizing observations of parallel electric fields of larger magnitude than the baseline case of the polarization field, the effect of two model fields on the electron distribution function is investigated. In one case the field is increased from the polarization field magnitude at 300 km to a maximum at the upper boundary of 800 km, and in another case a uniform field is added to the polarization field. Substantial perturbations of the low energy portion of the electron flux are produced: an upward directed electric field accelerates the downward directed flux of low-energy secondary electrons and decelerates the upward directed component. Above about 400 km the inhomogeneous magnetic field produces anisotropies in the angular distribution of the electron flux. The effects of the perturbed energy distributions on auroral spectral emission features are noted.

Effects of a Parallel Electric Field and the Geomagnetic Field in the Topside Ionosphere on Auroral and Photoelectron Energy Distributions

NASA Technical Reports Server (NTRS)

Min, Q.-L.; Lummerzheim, D.; Rees, M. H.; Stamnes, K.

1993-01-01

The consequences of electric field acceleration and an inhomogencous magnetic field on auroral electron energy distributions in the topside ionosphere are investigated. The one- dimensional, steady state electron transport equation includes elastic and inelastic collisions, an inhomogencous magnetic field, and a field-aligned electric field. The case of a self-consistent polarization electric field is considered first. The self-consistent field is derived by solving the continuity equation for all ions of importance, including diffusion of 0(+) and H(+), and the electron and ion energy equations to derive the electron and ion temperatures. The system of coupled electron transport, continuity, and energy equations is solved numerically. Recognizing observations of parallel electric fields of larger magnitude than the baseline case of the polarization field, the effect of two model fields on the electron distribution function in investigated. In one case the field is increased from the polarization field magnitude at 300 km to a maximum at the upper boundary of 800 km, and in another case a uniform field is added to the polarization field. Substantial perturbations of the low energy portion of the electron flux are produced: an upward directed electric field accelerates the downward directed flux of low-energy secondary electrons and decelerates the upward directed component. Above about 400 km the inhomogencous magnetic field produces anisotropies in the angular distribution of the electron flux. The effects of the perturbed energy distributions on auroral spectral emission features are noted.

Investigating Language and the Media: The Case of Newswriting

ERIC Educational Resources Information Center

Perrin, Daniel

2013-01-01

Drawing on a case study of newswriting, this article presents media linguistics as a subdiscipline of applied linguistics (AL), dealing with a distinctive field of language use. Language in the media is characterized by specific environments, functions, and structures. Medialinguistic research, however, tends to overcome disciplinary boundaries.…

A review of published research on adult dissociative identity disorder: 2000-2010.

PubMed

Boysen, Guy A; VanBergen, Alexandra

2013-01-01

The purpose of this study was to assess the scientific and etiological status of dissociative identity disorder (DID) by examining cases published from 2000 to 2010. In terms of scientific status, DID is a small but ongoing field of study. The review yielded 21 case studies and 80 empirical studies, presenting data on 1171 new cases of DID. A mean of 9 articles, each containing a mean of 17 new cases of DID, emerged each year. In terms of etiological status, many of the central criticisms of the disorder's validity remain unaddressed. Most cases of DID emerged from a small number of countries and clinicians. In addition, documented cases occurring outside treatment were almost nonexistent. Finally, people simulating DID in the laboratory were mostly indistinguishable from individuals with DID. Overall, DID is still a topic of study, but the research lacks the productivity and focus needed to resolve ongoing controversies surrounding the disorder.

Essential activities and knowledge domains of case management: new insights from the CCMC role and functions study.

PubMed

Tahan, Hussein

2006-01-01

The Commission for Case Manager Certification (CCMC) defines case management (CM) as "a collaborative process that assesses, plans, implements, coordinates, monitors, and evaluates the options and services required to meet an individual's health needs. [Case management] uses communication and available resources to promote quality, cost-effective outcomes." The practice of CM spans the entire health-care spectrum, including pre-acute, acute, and post-acute settings, and the involvement of varied care providers, such as nurses, social workers, rehabilitation counselors, physicians, and other allied health professionals. So what does it mean to practice as a case manager? What roles and job functions are performed and what knowledge is required of a professional in the field for effective practice? These highly relevant questions reflect the thinking of the CCMC commissioners when the latest Case Manager Role and Functions study was undertaken. The primary purpose of this research, which is conducted every 5 years by the CCMC, is to capture the current state of CM practice. This type of in-depth research is required to support an evidence-based certification examination such as the one offered by CCMC-the certified case manager (CCM) credential. Moreover, as the first and largest nationally accredited organization to certify US case managers, the CCMC recognizes its responsibility to undertake and promote scientifically conducted research in the field of CM.

Plasma expansion into a vacuum with an arbitrarily oriented external magnetic field

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

García-Rubio, F., E-mail: fernando.garcia.rubio@upm.es; Sanz, J.; Ruocco, A.

2016-01-15

Plasma expansion into a vacuum with an external magnetic field is studied under the ideal magnetohydrodynamic hypothesis. The inclination of the magnetic field with respect to the expansion direction is arbitrary, and both the perpendicular and the oblique cases are separately analyzed. A self-similar solution satisfying the boundary conditions is obtained. The interface with the vacuum is treated as a fluid surface, and jump conditions concerning the momentum conservation are imposed. The effect of the intensity of the magnetic field and its inclination is thoroughly studied, and the consistency of the solution for small and large inclinations is investigated.

MHD simulations of magnetic reconnection in a skewed three-dimensional tail configuration

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

Birn, J.; Hesse, M.

1991-01-01

Using the three-dimensional MHD code, the authors have studied the dynamic evolution of a non-symmetric magnetotail configuration, initiated by the sudden occurence of (anomalous) resistivity. The initial configuration included variations in all three space dimensions, consistent with average tail observations. In addition, it was skewed due to the presence of a net cross-tail magnetic field component B{sub yN} with a magnitude as typically observed, so that it lacked commonly assumed mirror symmetries around the midnight meridian and the equatorial planes. The field evolution was found to be very similar to that of a symmetric configuration studied earlier, indicating plasmoid formationmore » and ejection. The most noticeable new feature in the evolution of the individual field components is a reduction of B{sub y} on the reconnected dipole-like field lines earthward from the reconnection region. The topological structure of the magnetic field, however, defined by the field line connections, shows remarkable differences from the symmetric case, consistent with conclusions by Hughes and Sibeck (1987) and Birn et al. (1989). The plasmoid, which is a magnetically separate entity in the symmetric case, becomes open, connected initially with the Earth, but getting gradually connected with the interplanetary field, as reconnection of lobe field lines proceeds from the midnight region to the flanks of the tail. The separation of the plasmoid from the Earth is thus found to take a finite amount of time. When the plasmoid begins to separate from the Earth, a filamentary structure of field connections develops, not present in the spatial variation of the fields; this confirms predictions by Birn et al. (1989). A localization of the electric field parallel to the magnetic field is found consistent with conclusions on general magnetic reconnection.« less

Optimization of auxiliary optics in active-optics telescopes

NASA Astrophysics Data System (ADS)

Ragazzoni, Roberto

1993-04-01

The a-priori knowledge of the availability of active optics in a telescope can be advantageous in the design, optimization, and specification of tolerances for auxiliary devices of such a telescope. A modification of the merit function to be used into the optimization process is given, together with some considerations about the design procedure. The different effects of aberrations typically depending upon the position of the field of view (like coma or astigmatism), with those typically constant over the whole field of view (like spherical aberration) are explicitly taken into account in the mathematical treatment. A possible range of applications (prime focus corrector, off-axis field corrector, field flattener, reducing camera, and so on) is discussed. A case study for a field flattener is shown. The general result that can be derived from this paper is that tolerances are generally strongly relaxed, while a significant improvement of the nominal performances can be obtained only in particular cases or assuming a high dynamic range of the active optics correction.

Sub-solar Magnetopause Observation and Simulation of a Tripolar Guide-Magnetic Field Perturbation

NASA Astrophysics Data System (ADS)

Eriksson, S.; Cassak, P.; Retino, A.; Mozer, F.

2015-12-01

The Polar satellite recorded two reconnection exhausts within 6 min on 1 April 2001 at a rather symmetric sub-solar magnetopause that displayed different out-of-plane signatures for similar solar wind conditions. The first case was reported by Mozer et al. [2002] and displayed a bipolar guide field supporting a quadrupole Hall field consistent with a single X-line. The second case, however, shows the first known example of a tripolar guide-field perturbation at Earth's magnetopause reminiscent of the types of solar wind exhausts that Eriksson et al. [2014; 2015] have reported to be in agreement with multiple X-lines. A dedicated particle-in-cell simulation is performed for the prevailing conditions across the magnetopause. We propose an explanation in terms of asymmetric Hall magnetic fields due to a presence of a magnetic island between two X-lines, and discuss how higher resolution MMS observations can be used to further study this problem at the magnetopause.

Phase-transition Theory of Kerr Black Holes in the Electromagnetic Field

NASA Astrophysics Data System (ADS)

Liao, Yi; Gong, Xiao-Bo; Wu, Jian-Sheng

2017-02-01

For a Kerr black hole (KBH) with spin J and mass M in a steady electromagnetic field, a special Wald vacuum solution (WVS) has been found in the case of the no-source uniform field. For WVS, the Meissner effect (ME) occurs only in the the extreme KBH, where M2/J = 1, in this case, the magnetic field is totally excluded from the event horizon (EH) of KBH. However, WVS does not consider the Hawking radiation (HR) but treats KBH as an absolutely black body. If HR is added , researchers believe that the condition is not so restricted and it is possible for ME to occur in the less-extreme case. How less is the “less-extreme case”? This paper tries to answer this question. Since the Hawking temperature TH of KBH defined by HR is proportional to the surface gravity κ at the EH, this question is actually about the so-called existence/non-existence of ME (ME/NME) or superconducting phase transition. In this paper, we study the connection between the superconductivity of KBH-EH and the existence of Weyl fermion. Using thermodynamic formulas and the KBH state equation, we prove that the inherent-parameter condition for ME to occur is {M}2/J≤slant {ɛ }c=1.5 in force-free fields whether it be in the simple axisymmetric vacuum zero source case or in the non-zero source case, which can be described by the nonlinear Grad-Shafranov equation. We suggest that this is a second-order phase transition and calculate the critical exponents δ = 1 and η = 1/2 for the specific heat diverging at constant J.

Physical angular momentum separation for QED

NASA Astrophysics Data System (ADS)

Sun, Weimin

2017-04-01

We study the non-uniqueness problem of the gauge-invariant angular momentum separation for the case of QED, which stems from the recent controversy concerning the proper definitions of the orbital angular momentum and spin operator of the individual parts of a gauge field system. For the free quantum electrodynamics without matter, we show that the basic requirement of Euclidean symmetry selects a unique physical angular momentum separation scheme from the multitude of the possible angular momentum separation schemes constructed using the various gauge-invariant extensions (GIEs). Based on these results, we propose a set of natural angular momentum separation schemes for the case of interacting QED by invoking the formalism of asymptotic fields. Some perspectives on such a problem for the case of QCD are briefly discussed.

Analysis of scattering by a linear chain of spherical inclusions in an optical fiber

NASA Astrophysics Data System (ADS)

Chremmos, Ioannis D.; Uzunoglu, Nikolaos K.

2006-12-01

The scattering by a linear chain of spherical dielectric inclusions, embedded along the axis of an optical fiber, is analyzed using a rigorous integral equation formulation, based on the dyadic Green's function theory. The coupled electric field integral equations are solved by applying the Galerkin technique with Mie-type expansion of the field inside the spheres in terms of spherical waves. The analysis extends the previously studied case of a single spherical inhomogeneity inside a fiber to the multisphere-scattering case, by utilizing the classic translational addition theorems for spherical waves in order to analytically extract the direct-intersphere-coupling coefficients. Results for the transmitted and reflected power, on incidence of the fundamental HE11 mode, are presented for several cases.

The topology of intrasector reversals of the interplanetary magnetic field

NASA Astrophysics Data System (ADS)

Kahler, S. W.; Crooker, N. U.; Gosling, J. T.

1996-11-01

A technique has been developed recently to determine the polarities of interplanetary magnetic fields relative to their origins at the Sun by comparing energetic electron flow directions with local magnetic field directions. Here we use heat flux electrons from the Los Alamos National Laboratory (LANL) plasma detector on the ISEE 3 spacecraft to determine the field polarities. We examine periods within well-defined magnetic sectors when the field directions appear to be reversed from the normal spiral direction of the sector. About half of these intrasector field reversals (IFRs) are cases in which the polarities match those of the surrounding sectors, indicating that those fields have been folded back toward the Sun. The more interesting cases are those with polarity reversals. We find no clear cases of isolated reverse polarity fields, which suggests that islands of reverse polarity in the solar source dipole field probably do not exist. The IFRs with polarity reversals are strongly associated with periods of bidirectional electron flows, suggesting that those fields occur only in conjunction with closed fields. We propose that both those IFRs and the bidirectional flows are signatures of coronal mass ejections (CMEs). In that case, many interplanetary CMEs are larger and more complex than previously thought, consisting of both open and closed field components.

Population Genetics in Compressible Flows

NASA Astrophysics Data System (ADS)

Pigolotti, Simone; Benzi, Roberto; Jensen, Mogens H.; Nelson, David R.

2012-03-01

We study competition between two biological species advected by a compressible velocity field. Individuals are treated as discrete Lagrangian particles that reproduce or die in a density-dependent fashion. In the absence of a velocity field and fitness advantage, number fluctuations lead to a coarsening dynamics typical of the stochastic Fisher equation. We investigate three examples of compressible advecting fields: a shell model of turbulence, a sinusoidal velocity field and a linear velocity sink. In all cases, advection leads to a striking drop in the fixation time, as well as a large reduction in the global carrying capacity. We find localization on convergence zones, and very rapid extinction compared to well-mixed populations. For a linear velocity sink, one finds a bimodal distribution of fixation times. The long-lived states in this case are demixed configurations with a single interface, whose location depends on the fitness advantage.

Single-Case Design Research: Building the Evidence-Base in the Field of Education of Deaf and Hard of Hearing Students.

PubMed

Cannon, Joanna E; Guardino, Caroline; Antia, Shirin D; Luckner, John L

2016-01-01

The field of education of deaf and hard of hearing (DHH) students has a paucity of evidence-based practices (EBPs) to guide instruction. The authors discussed how the research methodology of single-case design (SCD) can be used to build EBPs through direct and systematic replication of studies. An overview of SCD research methods is presented, including an explanation of how internal and external validity issues are addressed, and why SCD is appropriate for intervention research with DHH children. The authors then examine the SCD research in the field according to quality indicators (QIs; at the individual level and as a body of evidence) to determine the existing evidence base. Finally, future replication areas are recommended to fill the gaps in SCD research with students who are DHH in order to add to the evidence base in the field.

Effects of flow on the dynamics of a ferromagnetic nematic liquid crystal

NASA Astrophysics Data System (ADS)

Potisk, Tilen; Pleiner, Harald; Svenšek, Daniel; Brand, Helmut R.

2018-04-01

We investigate the effects of flow on the dynamics of ferromagnetic nematic liquid crystals. As a model, we study the coupled dynamics of the magnetization, M , the director field, n , associated with the liquid crystalline orientational order, and the velocity field, v . We evaluate how simple shear flow in a ferromagnetic nematic is modified in the presence of small external magnetic fields, and we make experimentally testable predictions for the resulting effective shear viscosity: an increase by a factor of 2 in a magnetic field of about 20 mT. Flow alignment, a characteristic feature of classical uniaxial nematic liquid crystals, is analyzed for ferromagnetic nematics for the two cases of magnetization in or perpendicular to the shear plane. In the former case, we find that small in-plane magnetic fields are sufficient to suppress tumbling and thus that the boundary between flow alignment and tumbling can be controlled easily. In the latter case, we furthermore find a possibility of flow alignment in a regime for which one obtains tumbling for the pure nematic component. We derive the analogs of the three Miesowicz viscosities well-known from usual nematic liquid crystals, corresponding to nine different configurations. Combinations of these can be used to determine several dynamic coefficients experimentally.

Creativity in the Era of Social Networking: A Case Study at Tertiary Education in the Greek Context

ERIC Educational Resources Information Center

Theodotou, Evgenia; Papastathopoulos, Avraam

2015-01-01

This paper investigates the utilization of a social network tool in order to promote creativity in higher education. Buddypress was selected as a social network tool and de Bono's "6 thinking hats" as a creativity strategy. The participants were 17 undergraduate students from a case study in a University in Greece in the field of social…

The Use of Wireless Technology to Augment Problem-Based Learning in Special Education Preservice Teacher Training

ERIC Educational Resources Information Center

Blackbourn, J. M.; Fillingim, Jennifer G.; McCelland, Susan; Elrod, G. Franklin; Medley, Meagan B.; Kritsonis, Mary Alice; Ray, Jan

2008-01-01

This study examines the use of wireless laptop technology to support the application of problem-based learning (PBL) in a special education methods course. This field based course used a progressive disclosure process in weekly seminars to address issues posed in a case study. Eight scenarios, all related to the case, were presented to upper level…

Teacher Candidates and Latina/o English Learners at Fenton Elementary School: The Role of Early Clinical Experiences in Urban Teacher Education

ERIC Educational Resources Information Center

Nasir, Ambareen; Heineke, Amy J.

2014-01-01

This study investigates how early clinical experiences impact teacher candidates' learning and experiences with Latina/o English learners in a field-based program housed in a multilingual, urban elementary school. We draw on multiple-case study design and use discourse analysis to explore cases of three candidates. Findings reveal exploration of…

Student Teachers of Technology and Design into Industry: A Northern Ireland Case Study

ERIC Educational Resources Information Center

Gibson, Ken

2013-01-01

This paper, based in Northern Ireland, is a case study of an innovative programme which places year 3 B.Ed. post-primary student teachers of Technology and Design into industry for a five-day period. The industrial placement programme is set in an international context of evolving pre-service field placements and in a local context defined by the…

Upper Secondary Students' Situational Interest: A Case Study of the Role of a Zoo Visit in a Biology Class

ERIC Educational Resources Information Center

Dohn, Niels Bonderup

2013-01-01

This paper comprises a presentation of the findings of a case study that investigated how situational factors triggered 12th grade students' interest during a field trip to a zoo. The purpose was to identify sources of interest and to investigate the attributes that make them interesting. Students' interest was investigated by a descriptive…

[Basic thoughts on psychopharmacological interventions through psychotherapy of severe forms of post-traumatic stress disorder: a case study].

PubMed

Joksimovic, Ljiljana; Wöller, Wolfgang; Kunzke, Dieter

2013-01-01

The present paper focuses on clinical issues concerning the psychopharmacological treatment of severe forms of post-traumatic stress disorder (PTSD).Using a case study, we discuss problems in this field against the background of psychodynamic and psychotraumatological theories. We also present strategies for the appropriate use of psychotropic drugs in the psychotherapy of PTSD.

The Equity Journey: NewSchools Venture Fund and Lumina Foundation Pursue Diversity on the Road to Equity. Principles for Effective Education Grantmaking. Case Study No. 16

ERIC Educational Resources Information Center

Russell, Christina A.

2017-01-01

In this case study, Lumina Foundation and NewSchools Venture Fund, two grantmakers represented on Grantmakers for Education's Equity Impact Group, offer up strategies and learnings on their recent journeys in embedding diversity, equity and inclusion into their organizational cultures, grantmaking practices and field-building efforts. The major…

A Case-Based Electronic Learning Environment for Preservice Teacher Education.

ERIC Educational Resources Information Center

Angeli, Charoula; Bonk, Curtis Jay; Supplee, Lauren; Malikowski, Steve

This study took place within a teacher education program at a large Midwestern university with vast field observation placements around the state and the world. The purpose was to discover whether preservice teacher electronic conferencing on the World Wide Web about early field experiences can have an impact on the learning of educational…

Entering the (Postgraduate) Field: Underrepresented Students' Acquisition of Cultural and Social Capital in Graduate School Preparation Programs

ERIC Educational Resources Information Center

Winkle-Wagner, Rachelle; McCoy, Dorian L.

2016-01-01

Examining the role of humanities graduate preparation programs in facilitating underrepresented undergraduate students' socialization to the field (social context) of graduate education, this critical multisite case study finds that these programs are crucial to bidirectional anticipatory socialization for graduate education, where one gains new…

Validation of in situ networks via field sampling: case study in the South Fork Experimental Watershed

USDA-ARS?s Scientific Manuscript database

The calibration and validation of soil moisture remote sensing products is complicated by the logistics of installing a soil moisture network for a long term period in an active landscape. Therefore, these stations are located along field boundaries or in non-representative sites with regards to so...

Integrating a Learning Management System with a Student Assignments Digital Repository. A Case Study

ERIC Educational Resources Information Center

Díaz, Javier; Schiavoni, Alejandra; Osorio, María Alejandra; Amadeo, Ana Paola; Charnelli, María Emilia

2013-01-01

The integration of different platforms and information Systems in the academic environment is highly important and quite a challenge within the field of Information Technology. This integration allows for higher resource availability and improved interaction among intervening actors. In the field of e-Learning, where Learning Management Systems…

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…

Using a Transdisciplinary Model to Address Inequities in Field Placements for Teacher Candidates with Disabilities

ERIC Educational Resources Information Center

Bargerhuff, Mary Ellen; Cole, Donna J.; Teeters, Laura

2012-01-01

This paper examines the contradiction between articulated university policy on diversity/inclusion and actual practice with regard to field placements for teacher candidates with disabilities. Analysis of a unique case study involving a teacher candidate with traumatic brain injury illustrates the inequities of the traditional concern conference…

Recording the adult zebrafish cerebral field potential during pentylenetetrazole seizures

PubMed Central

Pineda, Ricardo; Beattie, Christine E.; Hall, Charles W.

2017-01-01

Although the zebrafish is increasingly used as a model organism to study epilepsy, no standard electrophysiological technique for recording electrographic seizures in adult fish exists. The purpose of this paper is to introduce a readily implementable technique for recording pentylenetetrazole seizures in the adult zebrafish. We find that we can consistently record a high quality field potential over the zebrafish cerebrum using an amplification of 5000 V/V and bandpass filtering at corner frequencies of 1.6 and 16 Hz. The cerebral field potential recordings show consistent features in the baseline, pre-seizure, seizure and post-seizure time periods that can be easily recognized by visual inspection as is the case with human and rodent electroencephalogram. Furthermore, numerical analysis of the field potential at the time of seizure onset reveals an increase in the total power, bandwidth and peak frequency in the power spectrum, as is also the case with human and rodent electroencephalogram. The techniques presented herein stand to advance the utility of the adult zebrafish in the study of epilepsy by affording an equivalent to the electroencephalogram used in mammalian models and human patients. PMID:21689682

Metaheuristic optimization approaches to predict shear-wave velocity from conventional well logs in sandstone and carbonate case studies

NASA Astrophysics Data System (ADS)

Emami Niri, Mohammad; Amiri Kolajoobi, Rasool; Khodaiy Arbat, Mohammad; Shahbazi Raz, Mahdi

2018-06-01

Seismic wave velocities, along with petrophysical data, provide valuable information during the exploration and development stages of oil and gas fields. The compressional-wave velocity (VP ) is acquired using conventional acoustic logging tools in many drilled wells. But the shear-wave velocity (VS ) is recorded using advanced logging tools only in a limited number of wells, mainly because of the high operational costs. In addition, laboratory measurements of seismic velocities on core samples are expensive and time consuming. So, alternative methods are often used to estimate VS . Heretofore, several empirical correlations that predict VS by using well logging measurements and petrophysical data such as VP , porosity and density are proposed. However, these empirical relations can only be used in limited cases. The use of intelligent systems and optimization algorithms are inexpensive, fast and efficient approaches for predicting VS. In this study, in addition to the widely used Greenberg–Castagna empirical method, we implement three relatively recently developed metaheuristic algorithms to construct linear and nonlinear models for predicting VS : teaching–learning based optimization, imperialist competitive and artificial bee colony algorithms. We demonstrate the applicability and performance of these algorithms to predict Vs using conventional well logs in two field data examples, a sandstone formation from an offshore oil field and a carbonate formation from an onshore oil field. We compared the estimated VS using each of the employed metaheuristic approaches with observed VS and also with those predicted by Greenberg–Castagna relations. The results indicate that, for both sandstone and carbonate case studies, all three implemented metaheuristic algorithms are more efficient and reliable than the empirical correlation to predict VS . The results also demonstrate that in both sandstone and carbonate case studies, the performance of an artificial bee colony algorithm in VS prediction is slightly higher than two other alternative employed approaches.

Implementation of small field radiotherapy dosimetry for spinal metastase case

NASA Astrophysics Data System (ADS)

Rofikoh, Wibowo, W. E.; Pawiro, S. A.

2017-07-01

The main objective of this study was to know dose profile of small field radiotherapy in the spinal metastase case with source axis distance (SAD) techniques. In addition, we evaluated and compared the dose planning of stereotactic body radiation therapy (SBRT) and conventional techniques to measurements with Exradin A16 and Gafchromic EBT3 film dosimeters. The results showed that film EBT3 had a highest precision and accuracy with the average of the standard deviation of ±1.7 and maximum discrepancy of 2.6 %. In addition, the average value of Full Wave Half Maximum (FWHM) and its largest deviation in small field size of 0.8 x 0.8 cm2 are 0.82 cm and 16.3 % respectively, while it was found around 2.36 cm and 3 % for the field size of 2.4 x 2.4 cm2. The comparison between penumbra width and the collimation was around of 37.1 % for the field size of 0.8 x 0.8 cm2, while it was found of 12.4 % for the field size of 2.4 x 2.4 cm2.

Evidence-Based Advances in Reptile Medicine.

PubMed

Mitchell, Mark A; Perry, Sean M

2017-09-01

Evidence-based medicine allows veterinarians to practice high-quality medicine, because the basis for all decision making is quantitative, objective, and reproducible. Case reports and case series are limited in their scope and application. Cross-sectional studies, likewise, cannot provide answers to specific variable testing with a temporal application. It is essential for the reptile specialty to expand into case-control studies, cohort studies, and experimental/intervention studies. Unfortunately, much of the reptile literature remains limited to descriptive studies. This article reviews current evidence-based topics in reptile medicine and shares how everyone practicing in the field can contribute to improving this specialty. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluation of a Teleform-based data collection system: a multi-center obesity research case study.

PubMed

Jenkins, Todd M; Wilson Boyce, Tawny; Akers, Rachel; Andringa, Jennifer; Liu, Yanhong; Miller, Rosemary; Powers, Carolyn; Ralph Buncher, C

2014-06-01

Utilizing electronic data capture (EDC) systems in data collection and management allows automated validation programs to preemptively identify and correct data errors. For our multi-center, prospective study we chose to use TeleForm, a paper-based data capture software that uses recognition technology to create case report forms (CRFs) with similar functionality to EDC, including custom scripts to identify entry errors. We quantified the accuracy of the optimized system through a data audit of CRFs and the study database, examining selected critical variables for all subjects in the study, as well as an audit of all variables for 25 randomly selected subjects. Overall we found 6.7 errors per 10,000 fields, with similar estimates for critical (6.9/10,000) and non-critical (6.5/10,000) variables-values that fall below the acceptable quality threshold of 50 errors per 10,000 established by the Society for Clinical Data Management. However, error rates were found to widely vary by type of data field, with the highest rate observed with open text fields. Copyright © 2014 Elsevier Ltd. All rights reserved.

Spatial two-photon coherence of the entangled field produced by down-conversion using a partially spatially coherent pump beam

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

Jha, Anand Kumar; Boyd, Robert W.

2010-01-15

We study the spatial coherence properties of the entangled two-photon field produced by parametric down-conversion (PDC) when the pump field is, spatially, a partially coherent beam. By explicitly treating the case of a pump beam of the Gaussian Schell-model type, we show that in PDC the spatial coherence properties of the pump field get entirely transferred to the spatial coherence properties of the down-converted two-photon field. As one important consequence of this study, we find that, for two-qubit states based on the position correlations of the two-photon field, the maximum achievable entanglement, as quantified by concurrence, is bounded by themore » degree of spatial coherence of the pump field. These results could be important by providing a means of controlling the entanglement of down-converted photons by tailoring the degree of coherence of the pump field.« less

[Fundamental and clinical studies on aspoxicillin in the field of pediatrics].

PubMed

Nobori, T; Katoh, Y; Ochiai, H; Ochiai, H; Kawai, K; Kamiya, H; Sakurai, M

1985-07-01

Fundamental and clinical studies were performed with aspoxicillin (ASPC), a new developed injectable broad penicillin, in pediatric infectious diseases, and the following results were obtained. Pharmacokinetics ASPC was administered to 2 cases at a dose of 20 mg/kg by one shot intravenous injection. The mean half-life (T 1/2) was 1.17 hours. The mean urinary excretion rate was 58.4% during 6 hours after ASPC treatment. In 3 cases of intravenous drip infusion with a period of 1 hour at a dose of 10 mg/kg (2 cases) and 20 mg/kg (1 case), the half-lives (T 1/2) were 1.7 hours, 3.5 hours and 1.0 hour, respectively. The urinary recovery rate during 6 hours after administration was 57.7%, 32.6% and 42.7%, respectively. At only one case treated with 10 mg/kg intravenous drip infusion, the half-life was prolonged and urinary excretion rate was lower than other 2 cases. Clinical study ASPC was administered 50-80 mg/kg/day for 4-8 days to 22 children comprising 6 tonsillitis, 2 bronchitis, 6 pneumonia and 8 urinary tract infections. Clinical efficacy was excellent in 13 cases, good in 8 cases and fair in 1 case, the total cure rate was 95%. As for the clinical response classified by diagnosis, the each efficacy rate of tonsillitis, bronchitis and pneumonia was 100%, and that of urinary tract infection was 87.5%. Clinical side effect and abnormal laboratory findings were not observed in any cases. From the above results, it was concluded that ASPC was one of the useful secure drug for treatment of infections in pediatric field.

Evaluation of the induced electric field and compliance procedure for a wireless power transfer system in an electrical vehicle.

PubMed

Laakso, Ilkka; Hirata, Akimasa

2013-11-07

In this study, an induced electric field in a human body is evaluated for the magnetic field leaked from a wireless power transfer system for charging an electrical vehicle. The magnetic field from the wireless power transfer system is modelled computationally, and its effectiveness is confirmed by comparison with the field measured in a previous study. The induced electric field in a human standing around the vehicle is smaller than the allowable limit prescribed in international guidelines, although the magnetic field strength in the human body is locally higher than the allowable external field strength. Correlation between the external magnetic field and the induced electric field is confirmed to be reasonable at least in the standing posture, which is the case discussed in the international standard. Based on this finding, we discussed and confirmed the applicability of a three-point magnetic field measurement at heights of 0.5, 1.0, and 1.5 m for safety compliance.

Design study of superconducting magnets for a combustion magnetohydrodynamic (MHD) generator

NASA Technical Reports Server (NTRS)

Thome, R. J.; Ayers, J. W.

1977-01-01

Design trade off studies for 13 different superconducting magnet systems were carried out. Based on these results, preliminary design characteristics were prepared for several superconducting magnet systems suitable for use with a combustion driven MHD generator. Each magnet generates a field level of 8 T in a volume 1.524 m (60 in.) long with a cross section 0.254 m x 0.254 m (10 in. x 10 in.) at the inlet and 0.406 m x .406 m (16 in. x 16 in.) at the outlet. The first design involves a racetrack coil geometry intended for operation at 4.2 K; the second design uses a racetrack geometry at 2.0 K; and the third design utilizes a rectangular saddle geometry at 4.2 K. Each case was oriented differently in terms of MHD channel axis and main field direction relative to gravity in order to evaluate fabrication ease. All cases were designed such that the system could be disassembled to allow for alteration of field gradient in the MHD channel by changing the angle between coils. Preliminary design characteristics and assembly drawings were generated for each case.

Sella turcica morphology and the pituitary gland-a new contribution to craniofacial diagnostics based on histology and neuroradiology.

PubMed

Kjær, Inger

2015-02-01

The present review summarizes two decades of published and unpublished studies on normal and pathological development of sella turcica and pituitary gland in humans. The pathological conditions are studied in known genotype deviations, syndromes, and other malformations. The studies include histological analyses of human prenatal material and profile radiographic analyses of human postnatal material, supplemented in a few cases with neuroradiology. Prenatal and postnatal results are compared. Similarities between prenatal and postnatal deviations in sella turcica morphology were demonstrated. Malformations in the pituitary gland were observed in several cases. For diagnostic purposes, the review distinguishes between deviations in the anterior wall and in the posterior wall of the sella turcica. Deviations in the anterior wall seem to be associated with deviations specifically in the frontonasal developmental field, while deviations in the posterior wall are often connected with malformations in the posterior structures, e.g. the cerebellum. In normal cases, minor variations in morphology are observed. In each pathological case, a specific malformation pattern was observed in sella turcica morphology, varying from mild to severe phenotype. The malformation in the sella turcica/pituitary gland can be associated with a malformation within a developmental field that forms the craniofacial region (frontonasal, maxillary, palatal, and mandibular fields), sometimes also involving the brain stem, thymus, thyroid, and heart (velocardiofacial syndrome). Pathological sella turcica morphology can also be associated with malformations in the cerebellum and larynx (Cri-du-Chat syndrome). This review demonstrates the value of combining profile radiographic diagnostics with neuroradiological diagnostics in cases with malformed sella turcicae. © The Author 2012. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Extragalactic Sources and Propagation of UHECRs

NASA Astrophysics Data System (ADS)

van Vliet, Arjen; Alves Batista, Rafael; Sigl, Günter

With the publicly available astrophysical simulation framework for propagating extraterrestrial UHE particles, CRPropa 3, it is now possible to study realistic UHECR source scenarios including deflections in Galactic and extragalactic magnetic fields in an efficient way. Here we discuss three recent studies that have already been done in that direction. The first one investigates what can be expected in the case of maximum allowed intergalactic magnetic fields. Here is shown that, even if voids contain strong magnetic fields, deflections of protons with energies ≳ 60 EeV from nearby sources might be small enough to allow for UHECR astronomy. The second study looks into several scenarios with a smaller magnetization focusing on large-scale anisotropies. Here is shown that the local source distribution can have a more significant effect on the large-scale anisotropy than the EGMF model. A significant dipole component could, for instance, be explained by a dominant source within 5 Mpc distance. The third study looks into whether UHECRs can come from local radio galaxies. If this is the case it is difficult to reproduce the observed low level of anisotropy. Therefore is concluded that the magnetic field strength in voids in the EGMF model used here is too low and/or there are additional sources of UHECRs that were not taken into account in these simulations.

Population-based mammography screening: comparison of screen-film and full-field digital mammography with soft-copy reading--Oslo I study.

PubMed

Skaane, Per; Young, Kari; Skjennald, Arnulf

2003-12-01

To compare screen-film and full-field digital mammography with soft-copy reading in a population-based screening program. Full-field digital and screen-film mammography were performed in 3,683 women aged 50-69 years. Two standard views of each breast were acquired with each modality. Images underwent independent double reading with use of a five-point rating scale for probability of cancer. Recall rates and positive predictive values were calculated. Cancer detection rates determined with both modalities were compared by using the McNemar test for paired proportions. Retrospective side-by-side analysis for conspicuity of cancers was performed by an external independent radiologist group with experience in both modalities. In 3,683 cases, 31 cancers were detected. Screen-film mammography depicted 28 (0.76%) malignancies, and full-field digital mammography depicted 23 (0.62%) malignancies. The difference between cancer detection rates was not significant (P =.23). The recall rate for full-field digital mammography (4.6%; 168 of 3,683 cases) was slightly higher than that for screen-film mammography (3.5%; 128 of 3,683 cases). The positive predictive value based on needle biopsy results was 46% for screen-film mammography and 39% for full-field digital mammography. Side-by-side image comparison for cancer conspicuity led to classification of 19 cancers as equal for probability of malignancy, six cancers as slightly better demonstrated at screen-film mammography, and six cancers as slightly better demonstrated at full-field digital mammography. There was no statistically significant difference in cancer detection rate between screen-film and full-field digital mammography. Cancer conspicuity was equal with both modalities. Full-field digital mammography with soft-copy reading is comparable to screen-film mammography in population-based screening.

IShTAR ICRF antenna field characterization in vacuum and plasma by using probe diagnostic

NASA Astrophysics Data System (ADS)

Usoltceva, Mariia; Ochoukov, Roman; D'Inca, Rodolphe; Jacquot, Jonathan; Crombé, Kristel; Kostic, Ana; Heuraux, Stéphane; Faudot, Eric; Noterdaeme, Jean-Marie

2017-10-01

RF sheath physics is one of the key topics relevant for improvements of ICRF heating systems, which are present on nearly all modern magnetic fusion machines. This paper introduces developement and validation of a new approach to understanding general RF sheath physics. The presumed reason of enhanced plasma-antenna interactions, parallel electric field, is not measured directly, but proposed to be obtained from simulations in COMSOL Multiphysics® Modeling Software. Measurements of RF magnetic field components with B-dot probes are done on a linear device IShTAR (Ion cyclotron Sheath Test ARrangement) and then compared to simulations. Good resulting accordance is suggested to be the criterion for trustworthiness of parallel electric field estimation as a component of electromagnetic field in modeling. A comparison between simulation and experiment for one magnetic field component in vacuum has demonstrated a close match. An additional complication to this ICRF antenna field characterization study is imposed by the helicon antenna which is used as a plasma ignition tool in the test arrangement. The plasma case, in contrast to the vacuum case, must be approached carefully, since the overlapping of ICRF antenna and helicon antenna fields occurs. Distinguishing of the two fields is done by an analysis of correlation between measurements with both antennas together and with each one separately.

Structure analysis of turbulent liquid phase by POD and LSE techniques

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

Munir, S., E-mail: shahzad-munir@comsats.edu.pk; Muthuvalu, M. S.; Siddiqui, M. I.

2014-10-24

In this paper, vortical structures and turbulence characteristics of liquid phase in both single liquid phase and two-phase slug flow in pipes were studied. Two dimensional velocity vector fields of liquid phase were obtained by Particle image velocimetry (PIV). Two cases were considered one single phase liquid flow at 80 l/m and second slug flow by introducing gas at 60 l/m while keeping liquid flow rate same. Proper orthogonal decomposition (POD) and Linear stochastic estimation techniques were used for the extraction of coherent structures and analysis of turbulence in liquid phase for both cases. POD has successfully revealed large energymore » containing structures. The time dependent POD spatial mode coefficients oscillate with high frequency for high mode numbers. The energy distribution of spatial modes was also achieved. LSE has pointed out the coherent structured for both cases and the reconstructed velocity fields are in well agreement with the instantaneous velocity fields.« less

What Is the Purpose of the Theses Addressing the Issue of Program Evaluation in Turkey? (The Case of Curriculum and Instruction: 1997-2015)

ERIC Educational Resources Information Center

Alkin-Sahin, Senar; Tunca, Nihal

2016-01-01

In the current study, the aim is to investigate the theses addressing the issue of program evaluation in the field of Curriculum and Instruction (C&I) in 1997-2015. The study employed the survey model. The universe of the study consists of totally 87 theses addressing the issue of program evaluation in the field of C&I in 1997-2015. As the…

[Bacteriological and clinical studies of flomoxef in the field of pediatrics].

PubMed

Kuno, K; Nakao, Y; Hayakawa, F; Miura, K; Miyajima, Y; Ishikawa, H; Kimura, H

1987-08-01

Bacteriological and clinical studies with flomoxef (FMOX, 6315-S), a new oxacephem antibiotic, were carried out in the field of pediatrics and the results obtained are summarized as follows: 1. The antimicrobial activity of FMOX against clinically isolated organisms was determined. FMOX had a good antimicrobial activity against Streptococcus pneumoniae, Escherichia coli, Haemophilus influenzae and especially against Staphylococcus aureus (including methicillin resistant S. aureus). 2. Mean serum concentrations of FMOX following intravenous bolus injection of 20 and 40 mg/kg (in 7 and 4 cases, respectively) were 35.3 and 77.7 micrograms/ml at 15 minutes after administration with mean serum half-lives (T1/2) of 0.75 and 0.95 hours and mean urinary recovery rates up to 6 hours after administration were 71.9 and 65.1%, respectively. 3. Twenty-five pediatric patients (19 cases of pneumonia, 1 case of pyothorax and 5 cases of urinary tract infection) were treated with FMOX in doses ranging from 50 to 138 mg/kg divided into 3 or 4 times a day. The rate of clinical effectiveness was 100% and the bacterial elimination rate was 90.6%. 4. No adverse reactions were observed. Abnormal laboratory findings were eosinophilia in 1, thrombocytosis in 2 and slight elevations of GOT and GPT in 3 patients. These results indicate the usefulness and the safety of FMOX in the treatment of bacterial infections in the pediatric field.

Electromagnetic fields and their impacts

NASA Astrophysics Data System (ADS)

Prša, M. A.; Kasaš-Lažetić, K. K.

2018-01-01

The main goal of this paper is to briefly recall some different electromagnetic field definitions, some macroscopic sources of electromagnetic fields, electromagnetic fields classification regarding time dependences, and the ways of field determination in concrete cases. After that, all the mechanisms of interaction between electromagnetic field and substance, on atomic level, are described in details. Interaction between substance and electric field is investigated separately from the substance and magnetic field interaction. It is demonstrated that, in all cases of the unique electromagnetic field, total interaction can be treated as a superposition of two separated interactions. Finally, the main electromagnetic fields surrounding us is cited and discussed.

Improving ethical knowledge and sensemaking from cases through elaborative interrogation and outcome valence.

PubMed

Johnson, James F; Bagdasarov, Zhanna; MacDougall, Alexandra E; Steele, Logan; Connelly, Shane; Devenport, Lynn D; Mumford, Michael D

2014-01-01

The case-based approach to learning is popular among many applied fields. However, results of case-based education vary widely on case content and case presentation. This study examined two aspects of case-based education-outcome valence and case elaboration methods-in a two-day case-based Responsible Conduct of Research (RCR) ethics education program. Results suggest that outcome information is an integral part of a quality case. Furthermore, valence consistent outcomes may have certain advantages over mixed valence outcome information. Finally, students enjoy and excel working with case material, and the use of elaborative interrogation techniques can significantly improve internally-focused ethical sensemaking strategies associated with personal biases, constraints, and emotions.

Debye screening of dislocations.

PubMed

Groma, I; Györgyi, G; Kocsis, B

2006-04-28

Debye-like screening by edge dislocations of some externally given stress is studied by means of a variational approach to coarse grained field theory. Explicitly given are the force field and the induced geometrically necessary dislocation (GND) distribution, in the special case of a single glide axis in 2D, for (i) a single edge dislocation and (ii) a dislocation wall. Numerical simulation demonstrates that the correlation in relaxed dislocation configurations is in good agreement with the induced GND in case (i). Furthermore, the result (ii) well predicts the experimentally observed decay length for the GND developing close to grain boundaries.

Designing field-controllable graphene-dot-graphene single molecule switches: A quantum-theoretical proof-of-concept under realistic operating conditions

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

Pejov, Ljupčo, E-mail: ljupcop@pmf.ukim.mk; Petreska, Irina; Kocarev, Ljupčo

2015-12-28

A theoretical proof of the concept that a particularly designed graphene-based moletronics device, constituted by two semi-infinite graphene subunits, acting as source and drain electrodes, and a central benzenoid ring rotator (a “quantum dot”), could act as a field-controllable molecular switch is outlined and analyzed with the density functional theory approach. Besides the ideal (0 K) case, we also consider the operation of such a device under realistic operating (i.e., finite-temperature) conditions. An in-depth insight into the physics behind device controllability by an external field was gained by thorough analyses of the torsional potential of the dot under various conditionsmore » (absence or presence of an external gating field with varying strength), computing the torsional correlation time and transition probabilities within the Bloembergen-Purcell-Pound formalism. Both classical and quantum mechanical tunneling contributions to the intramolecular rotation were considered in the model. The main idea that we put forward in the present study is that intramolecular rotors can be controlled by the gating field even in cases when these groups do not possess a permanent dipole moment (as in cases considered previously by us [I. Petreska et al., J. Chem. Phys. 134, 014708-1–014708-12 (2011)] and also by other groups [P. E. Kornilovitch et al., Phys. Rev. B 66, 245413-1–245413-7 (2002)]). Consequently, one can control the molecular switching properties by an external electrostatic field utilizing even nonpolar intramolecular rotors (i.e., in a more general case than those considered so far). Molecular admittance of the currently considered graphene-based molecular switch under various conditions is analyzed employing non-equilibrium Green’s function formalism, as well as by analysis of frontier molecular orbitals’ behavior.« less

Teaching mathematics remotely: changed practices in distance education

NASA Astrophysics Data System (ADS)

Lowrie, Tom; Jorgensen, Robyn

2012-09-01

This investigation explored the challenges of creating meaningful mathematics practices for a community engaged in Distance Education (DE). Specifically, the study maps the influence of new technologies on the practices of a learning community where mathematics was taught remotely. The theoretical framework of this study utilised Bourdieu's work on practice to consider the changed nature of the field, in this case, remote education provision, over time. By using Bourdieu's notion of field, we are better able to understand the ways in which practices and discourses shape particular ways of working in rural education provision. The results of the study show that Field 1 was innovative and beyond the non-school world, while Field 2 lagged behind the technological resources of the non-school world.

Sampling flies or sampling flaws? Experimental design and inference strength in forensic entomology.

PubMed

Michaud, J-P; Schoenly, Kenneth G; Moreau, G

2012-01-01

Forensic entomology is an inferential science because postmortem interval estimates are based on the extrapolation of results obtained in field or laboratory settings. Although enormous gains in scientific understanding and methodological practice have been made in forensic entomology over the last few decades, a majority of the field studies we reviewed do not meet the standards for inference, which are 1) adequate replication, 2) independence of experimental units, and 3) experimental conditions that capture a representative range of natural variability. Using a mock case-study approach, we identify design flaws in field and lab experiments and suggest methodological solutions for increasing inference strength that can inform future casework. Suggestions for improving data reporting in future field studies are also proposed.

Constructive tensorial group field theory I: The {U(1)} -{T^4_3} model

NASA Astrophysics Data System (ADS)

Lahoche, Vincent

2018-05-01

The loop vertex expansion (LVE) is a constructive technique using canonical combinatorial tools. It works well for quantum field theories without renormalization, which is the case of the field theory studied in this paper. Tensorial group field theories (TGFTs) are a new class of field theories proposed to quantize gravity. This paper is devoted to a very simple TGFT for rank three tensors with U(1) group and quartic interactions, hence nicknamed -. It has no ultraviolet divergence, and we show, with the LVE, that it is Borel summable in its coupling constant.

Magnetic Field Noise Changes Effect of Combined Magnetic Field on Gravitropic Reaction of Cress Roots.

NASA Astrophysics Data System (ADS)

Bogatina, Nina; Kordyum, Elizabeth; Sheykina, Nadezhda

The gravitropic reaction of cress roots in combined magnetic field was studied in details. It was shown that the negative roots gravitropism observed at the frequency of alternating component of combined magnetic field adjusted to the Ca ion cyclotron frequency could be observed only at Nayquist magnetic field noise level under 5 nT/Hz. While the magnetic noise level was increasing the negative gravitropism was disappearing. The inhibition of gravitropic reaction was observed in all cases. The effect was accompanied by the changes in the noise spectrum generated by cress roots.

Comparison of radiologist performance with photon-counting full-field digital mammography to conventional full-field digital mammography.

PubMed

Cole, Elodia B; Toledano, Alicia Y; Lundqvist, Mats; Pisano, Etta D

2012-08-01

The purpose of this study was to assess the performance of a MicroDose photon-counting full-field digital mammography (PCM) system in comparison to full-field digital mammography (FFDM) for area under the receiver-operating characteristic (ROC) curve (AUC), sensitivity, specificity, and feature analysis of standard-view mammography for women presenting for screening mammography, diagnostic mammography, or breast biopsy. A total of 133 women were enrolled in this study at two European medical centers, with 67 women who had a pre-existing 10-36 months FFDM enrolled prospectively into the study and 66 women who underwent breast biopsy and had screening PCM and diagnostic FFDM, including standard craniocaudal and mediolateral oblique views of the breast with the lesion, enrolled retrospectively. The case mix consisted of 49 cancers, 17 biopsy-benign cases, and 67 normal cases. Sixteen radiologists participated in the reader study and interpreted all 133 cases in both conditions, separated by washout period of ≥4 weeks. ROC curve and free-response ROC curve analyses were performed for noninferiority of PCM compared to FFDM using a noninferiority margin Δ value of 0.10. Feature analysis of the 66 cases with lesions was conducted with all 16 readers at the conclusion of the blinded reads. Mean glandular dose was recorded for all cases. The AUC for PCM was 0.947 (95% confidence interval [CI], 0.920-0.974) and for FFDM was 0.931 (95% CI, 0.898-0.964). Sensitivity per case for PCM was 0.936 (95% CI, 0.897-0.976) and for FFDM was 0.908 (95% CI, 0.856-0.960). Specificity per case for PCM was 0.764 (95% CI, 0.688-0.841) and for FFDM was 0.749 (95% CI, 0.668-0.830). Free-response ROC curve figures of merit were 0.920 (95% CI, 0.881-0.959) and 0.903 (95% CI, 0.858-0.948) for PCM and FFDM, respectively. Sensitivity per lesion was 0.903 (95% CI, 0.846-0.960) and 0.883 (95% CI, 0.823-0.944) for PCM and FFDM, respectively. The average false-positive marks per image of noncancer cases were 0.265 (95% CI, 0.171-0.359) and 0.281 (95% CI, 0.188-0.374) for PCM and FFDM, respectively. Noninferiority P values for AUC, sensitivity (per case and per lesion), specificity, and average false-positive marks per image were all statistically significant (P < .001). The noninferiority P value for free-response ROC was <.025, from the 95% CI for the difference. Feature analysis resulted in PCM being preferred to FFDM by the readers for ≥70% of the cases. The average mean glandular dose for PCM was 0.74 mGy (95% CI, 0.722-0.759 mGy) and for FFDM was 1.23 mGy (95% CI, 1.199-1.262 mGy). In this study, radiologist performance with PCM was not inferior to that with conventional FFDM at an average 40% lower mean glandular dose. Copyright © 2012 AUR. Published by Elsevier Inc. All rights reserved.

CoopEUS Case Study: Tsunami Modelling and Early Warning Systems for Near Source Areas (Mediterranean, Juan de Fuca).

NASA Astrophysics Data System (ADS)

Beranzoli, Laura; Best, Mairi; Chierici, Francesco; Embriaco, Davide; Galbraith, Nan; Heeseman, Martin; Kelley, Deborah; Pirenne, Benoit; Scofield, Oscar; Weller, Robert

2015-04-01

There is a need for tsunami modeling and early warning systems for near-source areas. For example this is a common public safety threat in the Mediterranean and Juan de Fuca/NE Pacific Coast of N.A.; Regions covered by the EMSO, OOI, and ONC ocean observatories. Through the CoopEUS international cooperation project, a number of environmental research infrastructures have come together to coordinate efforts on environmental challenges; this tsunami case study tackles one such challenge. There is a mutual need of tsunami event field data and modeling to deepen our experience in testing methodology and developing real-time data processing. Tsunami field data are already available for past events, part of this use case compares these for compatibility, gap analysis, and model groundtruthing. It also reviews sensors needed and harmonizes instrument settings. Sensor metadata and registries are compared, harmonized, and aligned. Data policies and access are also compared and assessed for gap analysis. Modelling algorithms are compared and tested against archived and real-time data. This case study will then be extended to other related tsunami data and model sources globally with similar geographic and seismic scenarios.

Topological Magnon Bands and Unconventional Superconductivity in Pyrochlore Iridate Thin Films.

PubMed

Laurell, Pontus; Fiete, Gregory A

2017-04-28

We theoretically study the magnetic properties of pyrochlore iridate bilayer and trilayer thin films grown along the [111] direction using a strong coupling approach. We find the ground state magnetic configurations on a mean field level and carry out a spin-wave analysis about them. In the trilayer case the ground state is found to be the all-in-all-out (AIAO) state, whereas the bilayer has a deformed AIAO state. For all parameters of the spin-orbit coupled Hamiltonian we study, the lowest magnon band in the trilayer case has a nonzero Chern number. In the bilayer case we also find a parameter range with nonzero Chern numbers. We calculate the magnon Hall response for both geometries, finding a striking sign change as a function of temperature. Using a slave-boson mean-field theory we study the doping of the trilayer system and discover an unconventional time-reversal symmetry broken d+id superconducting state. Our study complements prior work in the weak coupling limit and suggests that the [111] grown thin film pyrochlore iridates are a promising candidate for topological properties and unconventional orders.

Green and sustainable remediation (GSR) evaluation: framework, standards, and tool. A case study in Taiwan.

PubMed

Huang, Wen-Yen; Hung, Weiteng; Vu, Chi Thanh; Chen, Wei-Ting; Lai, Jhih-Wei; Lin, Chitsan

2016-11-01

Taiwan has a large number of poorly managed contaminated sites in need of remediation. This study proposes a framework, a set of standards, and a spreadsheet-based evaluation tool for implementing green and sustainable principles into remediation projects and evaluating the projects from this perspective. We performed a case study to understand how the framework would be applied. For the case study, we used a spreadsheet-based evaluation tool (SEFA) and performed field scale cultivation tests on a site contaminated with total petroleum hydrocarbons (TPHs). The site was divided into two lots: one treated by chemical oxidation and the other by bioremediation. We evaluated five core elements of green and sustainable remediation (GSR): energy, air, water resources, materials and wastes, and land and ecosystem. The proposed evaluation tool and field scale cultivation test were found to efficiently assess the effectiveness of the two remediation alternatives. The framework and related tools proposed herein can potentially be used to support decisions about the remediation of contaminated sites taking into account engineering management, cost effectiveness, and social reconciliation.

Unilateral pigmentary retinopathy--a review of literature and case presentation.

PubMed

Stamate, Alina-Cristina; Burcea, Marian; Zemba, Mihail

2016-01-01

To report a rare case of unilateral pigmentary retinopathy and describe the clinical and visual field characteristics of this particular case. We present the case of a 30-year-old male patient with a gradual loss of the visual field on his left eye (LE) for the past 10 years, with further gradual painless loss of his central visual field in the last year, and no similar symptoms in his right eye. His past medical and ocular history were unremarkable. No family history of acquired or inherited diseases was determined. Based on the history, clinical findings, and visual field examination, the diagnosis of unilateral pigmentary retinopathy was established. Visual acuity and visual field in the left eye (LE) were severely affected, while in the right eye (RE), they were completely normal. In this case, distinct features of pigmentary retinopathy were observed only in one eye, with the fellow eye being unaffected. The diagnosis requires a long follow-up period, visual field and electrophysiological testing to rule out a delayed onset of a bilateral form of pigmentary retinopathy.

The need for pediatric-specific triage criteria: results from the Florida Trauma Triage Study.

PubMed

Phillips, S; Rond, P C; Kelly, S M; Swartz, P D

1996-12-01

The objective of the Florida Trauma Triage Study was to assess the performance of state-adopted field triage criteria. The study addressed three specific age groups: pediatric (age < 15 years), adult (age 15-54 years), and geriatric (age 55+ years). Since 1990, Florida has used a uniform set of eight triage criteria, known as the trauma scorecard, for triaging adult trauma patients to state-approved trauma centers. However, only five of the criteria are recommended for use with pediatric patients. This article presents the findings regarding the performance of the scorecard when applied to a pediatric population. We used state trauma registry data linked to state hospital discharge data in a retrospective analysis of trauma patients transported by prehospital providers to any acute care hospital within nine selected Florida counties between July 1, 1991, and December 31, 1991. We used cross-table and logistic regression analysis to determine the ability of triage criteria to correctly identify patients who were retrospectively defined as major trauma. We applied the field criteria to physiologic and anatomy/mechanism of injury data contained in the trauma registry to "score" the patient as major or minor trauma. To make our retrospective determination of major or minor trauma we used the protocols developed by an expert medical panel as described by E. J. MacKenzie et al. (1990). We calculated sensitivity, specificity, and the corresponding over- and undertriage rates by comparing patient classifications (major or minor trauma) produced by the triage criteria and the retrospective algorithm. We used logistic regression to identify which triage criteria were statistically significant in predicting major trauma. Pediatric cases accounted for 9.2% of the total study population, 6.0% of all hospitalized cases, and 6.8% of all trauma deaths. Of the 1505 pediatric cases available for analysis, the triage criteria classified 269 cases as expected major trauma and 1236 cases as expected minor trauma. The retrospective algorithm classified 78 cases as expected major trauma and 1427 cases as expected minor trauma. The resulting specificity is 84.8% (15.2% overtriage), and the sensitivity is 66.7% (33.3% undertriage). Logistic regression indicated that, of the eight state-adopted field triage criteria, only the Glasgow coma score, ejection from vehicle, and penetrating injuries have a statistically significant impact on predicting major trauma in pediatric patients. Although the state-adopted trauma scorecard, applied to a pediatric population, produced acceptable overtriage, it did not produce acceptable undertriage. However, our undertriage rate is comparable to the results of other published studies on pediatric trauma. As a result of the Florida Trauma Triage Study, a new pediatric triage instrument was developed. It is currently being field-tested.

Tropical cyclone intensity change. A quantitative forecasting scheme

NASA Technical Reports Server (NTRS)

Dropco, K. M.; Gray, W. M.

1981-01-01

One to two day future tropical cyclone intensity change from both a composite and an individual case point-of-view are discussed. Tropical cyclones occurring in the Gulf of Mexico during the period 1957-1977 form the primary data source. Weather charts of the NW Atlantic were initially examined, but few differences were found between intensifying and non-intensifying cyclones. A rawinsonde composite analysis detected composite differences in the 200 mb height fields, the 850 mb temperature fields, the 200 mb zonal wind and the vertical shears of the zonal wind. The individual cyclones which make up the composite study were then separately examined using this composite case knowledge. Similar parameter differences were found in a majority of individual cases. A cyclone intensity change forecast scheme was tested against independent storm cases. Correct predictions of intensification or non-intensification could be made approximately 75% of the time.

Application of high-resolution melting curve analysis for typing of fowl adenoviruses in field cases of inclusion body hepatitis.

PubMed

Steer, P A; O'Rourke, D; Ghorashi, S A; Noormohammadi, A H

2011-05-01

Fowl adenoviruses (FAdVs) cause inclusion body hepatitis (IBH) in chickens. In this study, clinical cases of IBH from Australian broiler flocks were screened for the presence and genotype of FAdVs. Twenty-six IBH cases from commercial poultry farms were screened. Polymerase chain reaction (PCR) coupled with high-resolution melt (HRM) curve analysis (PCR/HRM genotyping) was used to determine the presence and genotype of FAdVs. For comparison, field isolates were also assessed by virus microneutralisation and nucleotide sequence analysis of the hexon loop 1 (Hex L1) gene. PCR detection of chicken anaemia virus (CAV) and infectious bursal disease virus (IBDV) was also employed. FAdV-8b and FAdV-11 were identified in 13 cases each. In one case, FAdV-1 was also identified. Cross-neutralisation was observed between the FAdV-11 field strain and the reference FAdV-2 and 11 antisera, a result also seen with the type 2 and 11 reference FAdVs. Field strains 1 and 8b were neutralised only by their respective type antisera. The FAdV-8b field strain was identical to the Australian FAdV vaccine strain (type 8b) in the Hex L1 region. The Hex L1 sequence of the FAdV-11 field strain had the highest identity to FAdV-11 (93.2%) and FAdV-2 (92.7%) reference strains. In the five cases tested for CAV and IBDV, neither virus was detected. The evidence suggested the presence of sufficient antibodies against CAV and IBD in the parent flocks and there was no indication of immunosuppression caused by these viruses. These results indicate that PCR/HRM genotyping is a reliable diagnostic method for FAdV identification and is more rapid than virus neutralisation and direct sequence analysis. Furthermore, they suggest that IBH in Australian broiler flocks is a primary disease resulting from two alternative FAdV strains from different species. © 2011 The Authors. Australian Veterinary Journal © 2011 Australian Veterinary Association.

Medical review licensing outcomes in drivers with visual field loss in Victoria, Australia

PubMed Central

Muir, Carlyn; Charlton, Judith L; Odell, Morris; Keeffe, Jill; Wood, Joanne; Bohensky, Megan; Fildes, Brian; Oxley, Jennifer; Bentley, Sharon; Rizzo, Matthew

2017-01-01

Background Good vision is essential for safe driving and studies have associated visual impairment with an increased crash risk. Currently, there is little information about the medical review of drivers with visual field loss. This study examines the prevalence of visual field loss among drivers referred for medical review in one Australian jurisdiction and investigates factors associated with licence outcome in this group. Methods A random sample of 10,000 (31.25 per cent) medical review cases was extracted for analysis from the Victorian licensing authority. Files were screened for the presence of six visual field-related medical conditions. Data were captured on a range of variables, including referral source, age, gender, health status, crash history and licence outcome. Prevalence analyses were univariate and descriptive. Logistic regression was used to assess factors associated with licence outcomes in the visual field loss group. Results Approximately 1.9 per cent of the 10,000 medical review cases screened had a visual field loss condition identified (n=194). Among the visual field loss group, 57.2 per cent were permitted to continue driving (conditional/unconditional licence). Primary referral sources were the police, self-referrals and general medical practitioners. Key factors associated with licence test outcomes were visual field condition, age group, crash involvement and referral to the Driver Licensing Authority’s Medical Advisors. Those who were younger had a crash involvement triggering referral and those who were referred to the Medical Advisors were more likely to have a positive licensing outcome. Conclusion The evidence base for making licensing decisions is complicated by the variable causes, patterns, progressions and measuring technologies for visual field loss. This study highlighted that the involvement of an expert medical advisory service in Victoria resulted in an increased likelihood that drivers with visual field loss will be allowed to continue driving. Further research is warranted to explore issues relating to severity of field loss and the capacity for compensation. PMID:27530283

Case Studies in Science Ethics

NASA Astrophysics Data System (ADS)

Williams, Karen

2010-03-01

Everyone in science should have ethics education training. I have seen graduate students taken advantage of by their mentors. Many of us have seen misconduct...but what should we do about it? Young scientists are often unaware of the rules in science and make mistakes because of their ignorance of the rules in that particular field of study. Then there are an increasing number of cases in the news of overt cases of misrepresentation in science. All are welcome to attend this discussion of case studies. A case study on topics such as: how to treat data properly, how our values in science affect our work, who gets authorship on scientific papers, who is first author on a paper, what you should do if you uncover misconduct or plagiarism in your university, and we will discuss the scientist's role in society. This will be a painless, non-confrontational small group, then large group discussion of each case

Electromagnetic Fields Associated with Commercial Solar Photovoltaic Electric Power Generating Facilities.

PubMed

Tell, R A; Hooper, H C; Sias, G G; Mezei, G; Hung, P; Kavet, R

2015-01-01

The southwest region of the United States is expected to experience an expansion of commercial solar photovoltaic generation facilities over the next 25 years. A solar facility converts direct current generated by the solar panels to three-phase 60-Hz power that is fed to the grid. This conversion involves sequential processing of the direct current through an inverter that produces low-voltage three-phase power, which is stepped up to distribution voltage (∼12 kV) through a transformer. This study characterized magnetic and electric fields between the frequencies of 0 Hz and 3 GHz at two facilities operated by the Southern California Edison Company in Porterville, CA and San Bernardino, CA. Static magnetic fields were very small compared to exposure limits established by IEEE and ICNIRP. The highest 60-Hz magnetic fields were measured adjacent to transformers and inverters, and radiofrequency fields from 5-100 kHz were associated with the inverters. The fields measured complied in every case with IEEE controlled and ICNIRP occupational exposure limits. In all cases, electric fields were negligible compared to IEEE and ICNIRP limits across the spectrum measured and when compared to the FCC limits (≥0.3 MHz).

Diffusion with Varying Drag; the Runaway Problem.

NASA Astrophysics Data System (ADS)

Rollins, David Kenneth

We study the motion of electrons in an ionized plasma of electrons and ions in an external electric field. A probability distribution function describes the electron motion and is a solution of a Fokker-Planck equation. In zero field, the solution approaches an equilibrium Maxwellian. For arbitrarily small field, electrons overcome the diffusive effects and are freely accelerated by the field. This is the electron runaway phenomenon. We treat the electric field as a small perturbation. We consider various diffusion coefficients for the one dimensional problem and determine the runaway current as a function of the field strength. Diffusion coefficients, non-zero on a finite interval are examined. Some non-trivial cases of these can be solved exactly in terms of known special functions. The more realistic case where the diffusion coefficient decays with velocity are then considered. To determine the runaway current, the equivalent Schrodinger eigenvalue problem is analysed. The smallest eigenvalue is shown to be equal to the runaway current. Using asymptotic matching a solution can be constructed which is then used to evaluate the runaway current. The runaway current is exponentially small as a function of field strength. This method is used to extract results from the three dimensional problem.

Understanding the rotation of coronal holes

NASA Astrophysics Data System (ADS)

Wang, Y.-M.; Sheeley, N. R., Jr.

1993-09-01

In an earlier study we found that the rotation of coronal holes could be understood on the basis of a nearly current-free coronal field, with the holes representing open magnetic regions. In this paper we illustrate the model by focusing on the case of CH1, the rigidly rotating boot-shaped hole observed by Skylab. We show that the interaction between the polar fields and the flux associated with active regions produces distortions in the coronal field configuration and thus in the polar-hole boundaries; these distortions corotate with the perturbing nonaxisymmetric flux. In the case of CH1, positive-polarity field lines in the northern hemisphere 'collided' with like-polarity field lines fanning out from a decaying active region complex located just below the equator, producing a midlatitude corridor of open field lines rotating at the rate of the active region complex. Sheared coronal holes result when nonaxisymmetric flux is present at high latitudes, or equivalently, when the photospheric neutral line extends to high latitudes. We demonstrate how a small active region, rotating at the local photospheric rate, can drift through a rigidly rotating hole like CH1. Finally, we discuss the role of field-line reconnection in maintaining a quasi-potential coronal configuration.

Nonlinear Right-Hand Polarized Wave in Plasma in the Electron Cyclotron Resonance Region

NASA Astrophysics Data System (ADS)

Krasovitskiy, V. B.; Turikov, V. A.

2018-05-01

The propagation of a nonlinear right-hand polarized wave along an external magnetic field in subcritical plasma in the electron cyclotron resonance region is studied using numerical simulations. It is shown that a small-amplitude plasma wave excited in low-density plasma is unstable against modulation instability with a modulation period equal to the wavelength of the excited wave. The modulation amplitude in this case increases with decreasing detuning from the resonance frequency. The simulations have shown that, for large-amplitude waves of the laser frequency range propagating in plasma in a superstrong magnetic field, the maximum amplitude of the excited longitudinal electric field increases with the increasing external magnetic field and can reach 30% of the initial amplitude of the electric field in the laser wave. In this case, the energy of plasma electrons begins to substantially increase already at magnetic fields significantly lower than the resonance value. The laser energy transferred to plasma electrons in a strong external magnetic field is found to increase severalfold compared to that in isotropic plasma. It is shown that this mechanism of laser radiation absorption depends only slightly on the electron temperature.

Spectral Absorption Properties of Atmospheric Aerosols

NASA Technical Reports Server (NTRS)

Bergstrom, R. W.; Pilewskie, P.; Russell, P. B.; Redemann, J.; Bond, T. C.; Quinn, P. K.; Sierau, B.

2007-01-01

We have determined the solar spectral absorption optical depth of atmospheric aerosols for specific case studies during several field programs (three cases have been reported previously; two are new results). We combined airborne measurements of the solar net radiant flux density and the aerosol optical depth with a detailed radiative transfer model for all but one of the cases. The field programs (SAFARI 2000, ACE Asia, PRIDE, TARFOX, INTEX-A) contained aerosols representing the major absorbing aerosol types: pollution, biomass burning, desert dust and mixtures. In all cases the spectral absorption optical depth decreases with wavelength and can be approximated with a power-law wavelength dependence (Absorption Angstrom Exponent or AAE). We compare our results with other recent spectral absorption measurements and attempt to briefly summarize the state of knowledge of aerosol absorption spectra in the atmosphere. We discuss the limitations in using the AAE for calculating the solar absorption. We also discuss the resulting spectral single scattering albedo for these cases.

Effective electric fields along realistic DTI-based neural trajectories for modelling the stimulation mechanisms of TMS

NASA Astrophysics Data System (ADS)

De Geeter, N.; Crevecoeur, G.; Leemans, A.; Dupré, L.

2015-01-01

In transcranial magnetic stimulation (TMS), an applied alternating magnetic field induces an electric field in the brain that can interact with the neural system. It is generally assumed that this induced electric field is the crucial effect exciting a certain region of the brain. More specifically, it is the component of this field parallel to the neuron’s local orientation, the so-called effective electric field, that can initiate neuronal stimulation. Deeper insights on the stimulation mechanisms can be acquired through extensive TMS modelling. Most models study simple representations of neurons with assumed geometries, whereas we embed realistic neural trajectories computed using tractography based on diffusion tensor images. This way of modelling ensures a more accurate spatial distribution of the effective electric field that is in addition patient and case specific. The case study of this paper focuses on the single pulse stimulation of the left primary motor cortex with a standard figure-of-eight coil. Including realistic neural geometry in the model demonstrates the strong and localized variations of the effective electric field between the tracts themselves and along them due to the interplay of factors such as the tract’s position and orientation in relation to the TMS coil, the neural trajectory and its course along the white and grey matter interface. Furthermore, the influence of changes in the coil orientation is studied. Investigating the impact of tissue anisotropy confirms that its contribution is not negligible. Moreover, assuming isotropic tissues lead to errors of the same size as rotating or tilting the coil with 10 degrees. In contrast, the model proves to be less sensitive towards the not well-known tissue conductivity values.

Ultra-wide-field imaging in diabetic retinopathy.

PubMed

Ghasemi Falavarjani, Khalil; Tsui, Irena; Sadda, Srinivas R

2017-10-01

Since 1991, 7-field images captured with 30-50 degree cameras in the Early Treatment Diabetic Retinopathy Study were the gold standard for fundus imaging to study diabetic retinopathy. Ultra-wide-field images cover significantly more area (up to 82%) of the fundus and with ocular steering can in many cases image 100% of the fundus ("panretinal"). Recent advances in image analysis of ultra-wide-field imaging allow for precise measurements of the peripheral retinal lesions. There is a growing consensus in the literature that ultra-wide-field imaging improves detection of peripheral lesions in diabetic retinopathy and leads to more accurate classification of the disease. There is discordance among studies, however, on the correlation between peripheral diabetic lesions and diabetic macular edema and optimal management strategies to treat diabetic retinopathy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Institutional Expansion: The Case of Grid Computing

ERIC Educational Resources Information Center

Kertcher, Zack

2010-01-01

Evolutionary and revolutionary approaches have dominated the study of scientific, technological and institutional change. Yet, being focused on change within a single field, these approaches have been mute about a third, pervasive process. This process is found in a variety of cases that range from open source software to the Monte Carlo method to…

Bioscience and the Sociology of Education: The Case for Biosocial Education

ERIC Educational Resources Information Center

Youdell, Deborah

2017-01-01

This article makes a case for biosocial education as a field of research and as a potential framework for education practice. The article engages with sociology of education's contemporary interests in embodiment and affect, the possibilities offered by concept studies, and uses of assemblage and complexity theory for thinking about educational…

Multicultural/Intercultural Education Issues in Pre-Service Teacher Education Courses: The Case of Greece

ERIC Educational Resources Information Center

Palaiologou, Nektaria; Dimitriadou, Catherine

2013-01-01

Teachers' education on Multicultural/Intercultural education issues constitutes a central field in the education of future teachers, i.e. the undergraduate students who attend educational studies at Pedagogical Departments. In this article we present the case of Greece, a southern European country, where Teachers' education on Intercultural issues…

Communication in a Web-Based Conferencing System: The Quality of Computer-Mediated Interactions.

ERIC Educational Resources Information Center

Angeli, Charoula; Valanides, Nicos; Bonk, Curtis J.

2003-01-01

Describes a study of undergraduates that investigated the extent to which an electronic conferencing system, COW (Conferencing on the Web) facilitated preservice teachers' communication outside their classroom when discussing teaching cases from their field experiences, and the potential of COW and case-based instruction to foster quality…

Application of travel time information for traffic management.

DOT National Transportation Integrated Search

2012-03-01

This report summarizes findings and implementations of probe vehicle data collection based on Bluetooth MAC address matching : technology. Probe vehicle travel time data are studied in the following field deployment case studies: analysis of traffic ...

Formation of curvature singularities on the interface between dielectric liquids in a strong vertical electric field.

PubMed

Kochurin, Evgeny A; Zubarev, Nikolay M; Zubareva, Olga V

2013-08-01

The nonlinear dynamics of the interface between two deep dielectric fluids in the presence of a vertical electric field is studied. We consider the limit of a strong external electric field where electrostatic forces dominate over gravitational and capillary forces. The nonlinear integrodifferential equations for the interface motion are derived under the assumption of small interfacial slopes. It is shown in the framework of these equations that, in the generic case, the instability development leads to the formation of root singularities at the interface in a finite time. The interfacial curvature becomes infinite at singular points, while the slope angles remain relatively small. The curvature is negative in the vicinity of singularities if the ratio of the permittivities of the fluids exceeds the inverse ratio of their densities, and it is positive in the opposite case (we consider that the lower fluid is heavier than the upper one). In the intermediate case, the interface evolution equations describe the formation and sharpening of dimples at the interface. The results obtained are applicable for the description of the instability of the interface between two magnetic fluids in a vertical magnetic field.

Comparison of different interpolation operators including nonlinear subdivision schemes in the simulation of particle trajectories

NASA Astrophysics Data System (ADS)

Bensiali, Bouchra; Bodi, Kowsik; Ciraolo, Guido; Ghendrih, Philippe; Liandrat, Jacques

2013-03-01

In this work, we compare different interpolation operators in the context of particle tracking with an emphasis on situations involving velocity field with steep gradients. Since, in this case, most classical methods give rise to the Gibbs phenomenon (generation of oscillations near discontinuities), we present new methods for particle tracking based on subdivision schemes and especially on the Piecewise Parabolic Harmonic (PPH) scheme which has shown its advantage in image processing in presence of strong contrasts. First an analytic univariate case with a discontinuous velocity field is considered in order to highlight the effect of the Gibbs phenomenon on trajectory calculation. Theoretical results are provided. Then, we show, regardless of the interpolation method, the need to use a conservative approach when integrating a conservative problem with a velocity field deriving from a potential. Finally, the PPH scheme is applied in a more realistic case of a time-dependent potential encountered in the edge turbulence of magnetically confined plasmas, to compare the propagation of density structures (turbulence bursts) with the dynamics of test particles. This study highlights the difference between particle transport and density transport in turbulent fields.

Theoretical pluralism in psychoanalytic case studies.

PubMed

Willemsen, Jochem; Cornelis, Shana; Geerardyn, Filip M; Desmet, Mattias; Meganck, Reitske; Inslegers, Ruth; Cauwe, Joachim M B D

2015-01-01

The aim of this study is to provide an overview of the scientific activity of different psychoanalytic schools of thought in terms of the content and production of case studies published on ISI Web of Knowledge. Between March 2013 and November 2013, we contacted all case study authors included in the online archive of psychoanalytic and psychodynamic case studies (www.singlecasearchive.com) to inquire about their psychoanalytic orientation during their work with the patient. The response rate for this study was 45%. It appears that the two oldest psychoanalytic schools, Object-relations psychoanalysis and Ego psychology or "Classical psychoanalysis" dominate the literature of published case studies. However, most authors stated that they feel attached to two or more psychoanalytic schools of thought. This confirms that the theoretical pluralism in psychoanalysis stretches to the field of single case studies. The single case studies of each psychoanalytic school are described separately in terms of methodology, patient, therapist, or treatment features. We conclude that published case studies features are fairly similar across different psychoanalytic schools. The results of this study are not representative of all psychoanalytic schools, as some do not publish their work in ISI ranked journals.

Theoretical pluralism in psychoanalytic case studies

PubMed Central

Willemsen, Jochem; Cornelis, Shana; Geerardyn, Filip M.; Desmet, Mattias; Meganck, Reitske; Inslegers, Ruth; Cauwe, Joachim M. B. D.

2015-01-01

The aim of this study is to provide an overview of the scientific activity of different psychoanalytic schools of thought in terms of the content and production of case studies published on ISI Web of Knowledge. Between March 2013 and November 2013, we contacted all case study authors included in the online archive of psychoanalytic and psychodynamic case studies (www.singlecasearchive.com) to inquire about their psychoanalytic orientation during their work with the patient. The response rate for this study was 45%. It appears that the two oldest psychoanalytic schools, Object-relations psychoanalysis and Ego psychology or “Classical psychoanalysis” dominate the literature of published case studies. However, most authors stated that they feel attached to two or more psychoanalytic schools of thought. This confirms that the theoretical pluralism in psychoanalysis stretches to the field of single case studies. The single case studies of each psychoanalytic school are described separately in terms of methodology, patient, therapist, or treatment features. We conclude that published case studies features are fairly similar across different psychoanalytic schools. The results of this study are not representative of all psychoanalytic schools, as some do not publish their work in ISI ranked journals. PMID:26483725

Video Capture of Plastic Surgery Procedures Using the GoPro HERO 3+

PubMed Central

Graves, Steven Nicholas; Shenaq, Deana Saleh; Langerman, Alexander J.

2015-01-01

Background: Significant improvements can be made in recoding surgical procedures, particularly in capturing high-quality video recordings from the surgeons’ point of view. This study examined the utility of the GoPro HERO 3+ Black Edition camera for high-definition, point-of-view recordings of plastic and reconstructive surgery. Methods: The GoPro HERO 3+ Black Edition camera was head-mounted on the surgeon and oriented to the surgeon’s perspective using the GoPro App. The camera was used to record 4 cases: 2 fat graft procedures and 2 breast reconstructions. During cases 1-3, an assistant remotely controlled the GoPro via the GoPro App. For case 4 the GoPro was linked to a WiFi remote, and controlled by the surgeon. Results: Camera settings for case 1 were as follows: 1080p video resolution; 48 fps; Protune mode on; wide field of view; 16:9 aspect ratio. The lighting contrast due to the overhead lights resulted in limited washout of the video image. Camera settings were adjusted for cases 2-4 to a narrow field of view, which enabled the camera’s automatic white balance to better compensate for bright lights focused on the surgical field. Cases 2-4 captured video sufficient for teaching or presentation purposes. Conclusions: The GoPro HERO 3+ Black Edition camera enables high-quality, cost-effective video recording of plastic and reconstructive surgery procedures. When set to a narrow field of view and automatic white balance, the camera is able to sufficiently compensate for the contrasting light environment of the operating room and capture high-resolution, detailed video. PMID:25750851

Sequential and direct ionic excitation in the strong-field ionization of 1-butene molecules.

PubMed

Schell, Felix; Boguslavskiy, Andrey E; Schulz, Claus Peter; Patchkovskii, Serguei; Vrakking, Marc J J; Stolow, Albert; Mikosch, Jochen

2018-05-18

We study the Strong-Field Ionization (SFI) of the hydrocarbon 1-butene as a function of wavelength using photoion-photoelectron covariance and coincidence spectroscopy. We observe a striking transition in the fragment-associated photoelectron spectra: from a single Above Threshold Ionization (ATI) progression for photon energies less than the cation D0-D1 gap to two ATI progressions for a photon energy greater than this gap. For the first case, electronically excited cations are created by SFI populating the ground cationic state D0, followed by sequential post-ionization excitation. For the second case, direct sub-cycle SFI to the D1 excited cation state contributes significantly. Our experiments access ionization dynamics in a regime where strong-field and resonance-enhanced processes can interplay.

Higher Spin Fields in Three-Dimensional Gravity

NASA Astrophysics Data System (ADS)

Lepage-Jutier, Arnaud

In this thesis, we study the effects of massless higher spin fields in three-dimensional gravity with a negative cosmological constant. First, we introduce gravity in Anti-de Sitter (AdS) space without the higher spin gauge symmetry. We recapitulate the semi-classical analysis that outlines the duality between quantum gravity in three dimensions with a negative cosmological constant and a conformal field theory on the asymptotic boundary of AdS 3. We review the statistical interpretation of the black hole entropy via the AdS/CFT correspondence and the modular invariance of the partition function of a CFT on a torus. For the case of higher spin theories in AdS 3 we use those modular properties to bound the amount of gauge symmetry present. We then discuss briefly cases that can evade this bound.

Field-based random sampling without a sampling frame: control selection for a case-control study in rural Africa.

PubMed

Crampin, A C; Mwinuka, V; Malema, S S; Glynn, J R; Fine, P E

2001-01-01

Selection bias, particularly of controls, is common in case-control studies and may materially affect the results. Methods of control selection should be tailored both for the risk factors and disease under investigation and for the population being studied. We present here a control selection method devised for a case-control study of tuberculosis in rural Africa (Karonga, northern Malawi) that selects an age/sex frequency-matched random sample of the population, with a geographical distribution in proportion to the population density. We also present an audit of the selection process, and discuss the potential of this method in other settings.

Absorption of electromagnetic radiation in a quantum wire with an anisotropic parabolic potential in a transverse magnetic field

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

Karpunin, V. V., E-mail: karpuninvv@mail.ru; Margulis, V. A., E-mail: theorphysics@mrsu.ru

2016-06-15

An analytical expression for the coefficient of absorption of electromagnetic radiation by electrons in a quantum wire in a magnetic field is derived. The case of a magnetic field transverse with respect to the wire axis is considered. The resonance character of absorption is shown, and the resonance frequencies as functions of the field are determined. The effect of the scattering of electrons at optical phonons is studied, and it is shown that scattering is responsible for additional resonance absorption peaks.

Guidelines for Reporting Case Studies on Extracorporeal Treatments in Poisonings: Methodology

PubMed Central

Lavergne, Valéry; Ouellet, Georges; Bouchard, Josée; Galvao, Tais; Kielstein, Jan T; Roberts, Darren M; Kanji, Salmaan; Mowry, James B; Calello, Diane P; Hoffman, Robert S; Gosselin, Sophie; Nolin, Thomas D; Goldfarb, David S; Burdmann, Emmanuel A; Dargan, Paul I; Decker, Brian Scott; Hoegberg, Lotte C; Maclaren, Robert; Megarbane, Bruno; Sowinski, Kevin M; Yates, Christopher; Mactier, Robert; Wiegand, Timothy; Ghannoum, Marc

2014-01-01

A literature review performed by the EXtracorporeal TReatments In Poisoning (EXTRIP) workgroup highlighted deficiencies in the existing literature, especially the reporting of case studies. Although general reporting guidelines exist for case studies, there are none in the specific field of extracorporeal treatments in toxicology. Our goal was to construct and propose a checklist that systematically outlines the minimum essential items to be reported in a case study of poisoned patients undergoing extracorporeal treatments. Through a modified two-round Delphi technique, panelists (mostly chosen from the EXTRIP workgroup) were asked to vote on the pertinence of a set of items to identify those considered minimally essential for reporting complete and accurate case reports. Furthermore, independent raters validated the clarity of each selected items between each round of voting. All case reports containing data on extracorporeal treatments in poisoning published in Medline in 2011 were reviewed during the external validation rounds. Twenty-one panelists (20 from the EXTRIP workgroup and an invited expert on pharmacology reporting guidelines) participated in the modified Delphi technique. This group included journal editors and experts in nephrology, clinical toxicology, critical care medicine, emergency medicine, and clinical pharmacology. Three independent raters participated in the validation rounds. Panelists voted on a total of 144 items in the first round and 137 items in the second round, with response rates of 96.3% and 98.3%, respectively. Twenty case reports were evaluated at each validation round and the independent raters' response rate was 99.6% and 98.8% per validation round. The final checklist consists of 114 items considered essential for case study reporting. This methodology of alternate voting and external validation rounds was useful in developing the first reporting guideline for case studies in the field of extracorporeal treatments in poisoning. We believe that this guideline will improve the completeness and transparency of published case reports and that the systematic aggregation of information from case reports may provide early signals of effectiveness and/or harm, thereby improving healthcare decision-making. PMID:24890576

The Contribution of Postgraduation--Lato Sensu--At Distance for Training Health Field Professionals: A Case Study at A Brazilian Federal University

ERIC Educational Resources Information Center

Grossi, Márcia Gorett Ribeiro; Silqueira, Salete Maria de Fátima; Gomes, Laryssa Cristina Castro; Silva, Lívia de Cássia; Saleme, Angela Maria Bissoli

2017-01-01

This article aimed to verify the opinions of health professionals who are looking for distance learning courses offered by distance learning. In order to do so, a case study was carried out in 2017 at the Federal University of Minas Gerais (UFMG), specifically in a course offered in the distance modality by the Nursing School: "Specialization…

A View from the Elementary Schools: The State of Reform in Chicago. A Report of the Steering Committee, Consortium on Chicago School Research.

ERIC Educational Resources Information Center

Bryk, Anthony S.; And Others

Through a synthesis of ongoing case studies covering over 500 schools, this report highlights the story of school reform in the Chicago Public Schools (Illinois) at the elementary school level. The analysis draws on a case-study syntheses of field research over the past 3 years, new analyses of survey data from principals and teachers, and…

Equipping Liberal Arts Students with Skills in Data Analytics: Drake University Partners with Regional Businesses to Offer New Programs in a Rapidly Growing Field. A BHEF Case Study

ERIC Educational Resources Information Center

Business-Higher Education Forum, 2016

2016-01-01

This case study examines how Business-Higher Education Forum (BHEF) member Drake University, a private university with a strong liberal arts tradition, is equipping its students to become data-enabled professionals. Through the collaboration of its business and higher education members, BHEF launched the National Higher Education and Workforce…

History of Physics as a Tool to Detect the Conceptual Difficulties Experienced by Students: The Case of Simple Electric Circuits in Primary Education

ERIC Educational Resources Information Center

Leone, Matteo

2014-01-01

The present paper advocates the use of History of Science into the teaching of science in primary education through a case study in the field of electricity. In this study, which provides both historical and experimental evidence, a number of conceptual difficulties faced by early nineteenth century physicists are shown to be a useful tool to…

Beacons of Light, Rays, or Sun Catchers? A Case Study of the Positioning of Literacy Teachers and Their Knowledge in Neoliberal Times

ERIC Educational Resources Information Center

Hibbert, Kathryn M.; Heydon, Rachel M.; Rich, Sharon J.

2008-01-01

This paper reports on a case study of a "lead literacy teacher" initiative in one Canadian province. This initiative is related to a ''minority world'' trend in teacher in-service that seeks to develop "experts" in a field with the intent that such experts can help other teachers to raise student achievement for the betterment…

Meeting Common Core English Language Arts and English Language Development Standards with Character Education Lesson Plans in Alternative Education Grades 9 through 12

ERIC Educational Resources Information Center

Hoedel, Joseph M.; Lee, Robert E.

2016-01-01

This is a case study in which the Character Development and Leadership Program replaced an alternative high school's traditional English language offerings. A triangulated case study used student records, field notes, and interviews of stakeholders to compare the academic year prior to this substitution and the 2 academic years following it. All 3…

Development and Advanced Analysis of Dynamic and Static Casing Strain Monitoring to Characterize the Orientation and Dimensions of Hydraulic Fractures

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

Bruno, Michael; Ramos, Juan; Lao, Kang

Horizontal wells combined with multi-stage hydraulic fracturing have been applied to significantly increase production from low permeability formations, contributing to expanded total US production of oil and gas. Not all applications are successful, however. Field observations indicate that poorly designed or placed fracture stages in horizontal wells can result in significant well casing deformation and damage. In some instances, early fracture stages have deformed the casing enough so that it is not possible to drill out plugs in order to complete subsequent fracture stages. Improved fracture characterization techniques are required to identify potential problems early in the development of themore » field. Over the past decade, several new technologies have been presented as alternatives to characterize the fracture geometry for unconventional reservoirs. Monitoring dynamic casing strain and deformation during hydraulic fracturing represents one of these new techniques. The objective of this research is to evaluate dynamic and static strains imposed on a well casing by single and multiple stage fractures, and to use that information in combination with numerical inversion techniques to estimate fracture characteristics such as length, orientation and post treatment opening. GeoMechanics Technologies, working in cooperation with the Department of Energy, Small Business Innovation Research through DOE SBIR Grant No: DE-SC-0017746, is conducting a research project to complete an advanced analysis of dynamic and static casing strain monitoring to characterize the orientation and dimensions of hydraulic fractures. This report describes our literature review and technical approach. The following conclusions summarize our review and simulation results to date: A literature review was performed related to the fundamental theoretical and analytical developments of stress and strain imposed by hydraulic fracturing along casing completions and deformation monitoring techniques. Analytical solutions have been developed to understand the mechanisms responsible for casing deformation induced by hydraulic fracturing operations. After reviewing a range of casing deformation techniques, including fiber optic sensors, borehole ultrasonic tools and electromagnetic tools, we can state that challenges in deployment, data acquisition and interpretation must still be overcome to ensure successful application of strain measurement and inversion techniques to characterize hydraulic fractures in the field. Numerical models were developed to analyze induced strain along casing, cement and formation interfaces. The location of the monitoring sensor around the completion, mechanical properties of the cement and its condition in the annular space can impact the strain measurement. Field data from fiber optic sensors were evaluated to compare against numerical models. A reasonable match for the fracture height characterization was obtained. Discrepancies in the strain magnitude between the field data and the numerical model was observed and can be caused by temperature effects, the cement condition in the well and the perturbation at the surface during injection. To avoid damage in the fiber optic cable during the perforation (e.g. when setting up multi stage HF scenarios), oriented perforation technologies are suggested. This issue was evidenced in the analyzed field data, where it was not possible to obtain strain measurement below the top of the perforation. This presented a limitation to characterize the entire fracture geometry. The comparison results from numerical modeling and field data for fracture characterization shows that the proposed methodology should be validated with alternative field demonstration techniques using measurements in an offset observation well to monitor and measure the induced strain. We propose to expand on this research in Phase II with a further study of multi-fracture characterization and field demonstration for horizontal wells.« less

Topological String Theory and Enumerative Geometry

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

Song, Y. S

In this thesis we investigate several problems which have their roots in both topological string theory and enumerative geometry. In the former case, underlying theories are topological field theories, whereas the latter case is concerned with intersection theories on moduli spaces. A permeating theme in this thesis is to examine the close interplay between these two complementary fields of study. The main problems addressed are as follows: In considering the Hurwitz enumeration problem of branched covers of compact connected Riemann surfaces, we completely solve the problem in the case of simple Hurwitz numbers. In addition, utilizing the connection between Hurwitzmore » numbers and Hodge integrals, we derive a generating function for the latter on the moduli space {bar M}{sub g,2} of 2-pointed, genus-g Deligne-Mumford stable curves. We also investigate Givental's recent conjecture regarding semisimple Frobenius structures and Gromov-Witten invariants, both of which are closely related to topological field theories; we consider the case of a complex projective line P{sup 1} as a specific example and verify his conjecture at low genera. In the last chapter, we demonstrate that certain topological open string amplitudes can be computed via relative stable morphisms in the algebraic category.« less

Evaluation of the Persistent Issues in History Laboratory for Virtual Field Experience (PIH-LVFE)

ERIC Educational Resources Information Center

Brush, Thomas; Saye, John; Kale, Ugur; Hur, Jung Won; Kohlmeier, Jada; Yerasimou, Theano; Guo, Lijiang; Symonette, Simone

2009-01-01

The Persistent Issues in History Laboratory for Virtual Field Experience (PIH-LVFE) combines a database of video cases of authentic classroom practices with multiple resources and tools to enable pre-service social studies teachers to virtually observe teachers implementing problem-based learning activities. In this paper, we present the results…

Urbanization dramatically altered the water balances of a paddy field dominated basin in southern China

Treesearch

L. Hao; G. Sun; Y. Liu; J. Wan; M. Qin; H. Qian; C. Liu; R. John; P. Fan; J. Chen

2015-01-01

Rice paddy fields provide important ecosystem services (e.g., food production, water retention, carbon sequestration) to a large population globally. However, these benefits are declining as a result of rapid environmental and socioeconomic transformations characterized by population growth, urbanization, and climate change in many Asian countries. This case study...

Women in STEM at a California Community College: A Case Study

ERIC Educational Resources Information Center

Whelan, Garrett C.

2017-01-01

Women are underrepresented in the fields of Science, Technology, Engineering and Mathematics (STEM) from high school to college and into employment. As these are the fastest growing and highest paying fields of the economy this means women are missing the large economic benefits. While there has been a great deal of research into female STEM…

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…

The Case of Educational Peacebuilding inside the United Nations Universities: A Review and Critique

ERIC Educational Resources Information Center

Kester, Kevin

2017-01-01

This article examines higher education for peace inside the United Nations (UN). It offers an overview and synthesis of core concepts, organizing frameworks and theoretical premises in the field of peace and conflict studies (PACS) higher education and in the UN universities in particular, as the field aspires toward transformative learning and…

Discursive Power and the New Labor Force: The Metamorphosis of a Speech Community

ERIC Educational Resources Information Center

Miles, Christopher

2010-01-01

This article describes the results of a six-month ethnographic case study of a French immigrant of Senegalese descent and how he recreates the culture of an American company's speech community. Data were collected through interviews, field notes, and shadowing the participant at his place of employment. The transcribed interviews and field notes…

Field responses of predaceous arthropods to methyl salicylate: a meta-analysis and case study in cranberries

USDA-ARS?s Scientific Manuscript database

Methyl salicylate (MeSA) is an herbivore-induced plant volatile (HIPV) that has shown potential in attracting natural enemies. Here, we conducted a meta-analysis to evaluate the magnitude of natural enemy response to MeSA in the field, and tested its attractiveness to insect predators in commercial...

Embedding Research in a Field-Based Module through Peer Review and Assessment for Learning

ERIC Educational Resources Information Center

Nicholson, Dawn T.

2011-01-01

A case study is presented of embedding research in a final year undergraduate, field-based, physical geography module. The approach is holistic, whereby research-based learning activities simulate the full life cycle of research from inception through to peer review and publication. The learning, teaching and assessment strategy emphasizes the…

Urban Farming as a Civic Virtue Development in the Environmental Field

ERIC Educational Resources Information Center

Prasetiyo, Wibowo Heru; Budimansyah, Dasim; Roslidah, Navila

2016-01-01

This research aims to describe the impact of urban farming carried out by Bandung Berkebun community as an attempt to develop the civic virtue in the environmental field. Research method used is a case study with qualitative approach. The results show that this program has educational, economic, social, and ecological impact to the society. This…

Factors Affecting Students' Career Choice in Accounting: The Case of a Turkish University

ERIC Educational Resources Information Center

Uyar, Ali; Güngörmüs, Ali Haydar; Kuzey, Cemil

2011-01-01

This study investigates the reasons that influence students' career choices in accounting. In order to determine these reasons, a questionnaire survey has been employed. The empirical findings can be divided into two categories. First, students who have a desire to work in accounting field assume that accounting field provides good job…

Preservice Teacher Sense-Making as They Learn to Teach Reading as Seen through Computer-Mediated Discourse

ERIC Educational Resources Information Center

Stefanski, Angela J.; Leitze, Amy; Fife-Demski, Veronica M.

2018-01-01

This collective case study used methods of discourse analysis to consider what computer-mediated collaboration might reveal about preservice teachers' sense-making in a field-based practicum as they learn to teach reading to children identified as struggling readers. Researchers agree that field-based experiences coupled with time for reflection…

A Case Study of Career Change Professionals in Middle School Teaching

ERIC Educational Resources Information Center

Cutler, Jessica Lynn

2017-01-01

The entrance of second-career professionals to the middle grades math/science education field indicates a shift from the typical work avenues to the field of Education. School culture/climate may also be affected by the insertion of older, experienced second-career professionals. Many educators will refer to the feeling of a "calling" to…

Student Voice Use and Vocal Health during an All-State Chorus Event

ERIC Educational Resources Information Center

Daugherty, James F.; Manternach, Jeremy N.; Price, Kathy K.

2011-01-01

This field-based case study documented students' (N = 256) voice use and voice health perceptions during a 3-day all-state high school chorus event through daily surveys, phonation duration data, analysis of rehearsal voice use behaviors, and field notes. Among the primary results are the following: (a) First and final day survey comparisons…

A Content Analysis of Dissertations in the Field of Educational Technology: The Case of Turkey

ERIC Educational Resources Information Center

Durak, Gurhan; Cankaya, Serkan; Yunkul, Eyup; Misirli, Zeynel Abidin

2018-01-01

The present study aimed at conducting content analysis on dissertations carried out so far in the field of Educational Technology in Turkey. A total of 137 dissertations were examined to determine the key words, academic discipline, research areas, theoretical frameworks, research designs and models, statistical analyses, data collection tools,…

The order and priority of research and design method application within an assistive technology new product development process: a summative content analysis of 20 case studies.

PubMed

Torrens, George Edward

2018-01-01

Summative content analysis was used to define methods and heuristics from each case study. The review process was in two parts: (1) A literature review to identify conventional research methods and (2) a summative content analysis of published case studies, based on the identified methods and heuristics to suggest an order and priority of where and when were used. Over 200 research and design methods and design heuristics were identified. From the review of the 20 case studies 42 were identified as being applied. The majority of methods and heuristics were applied in phase two, market choice. There appeared a disparity between the limited numbers of methods frequently used, under 10 within the 20 case studies, when hundreds were available. Implications for Rehabilitation The communication highlights a number of issues that have implication for those involved in assistive technology new product development: •The study defined over 200 well-established research and design methods and design heuristics that are available for use by those who specify and design assistive technology products, which provide a comprehensive reference list for practitioners in the field; •The review within the study suggests only a limited number of research and design methods are regularly used by industrial design focused assistive technology new product developers; and, •Debate is required within the practitioners working in this field to reflect on how a wider range of potentially more effective methods and heuristics may be incorporated into daily working practice.

Building a 3D faulted a priori model for stratigraphic inversion: Illustration of a new methodology applied on a North Sea field case study

NASA Astrophysics Data System (ADS)

Rainaud, Jean-François; Clochard, Vincent; Delépine, Nicolas; Crabié, Thomas; Poudret, Mathieu; Perrin, Michel; Klein, Emmanuel

2018-07-01

Accurate reservoir characterization is needed all along the development of an oil and gas field study. It helps building 3D numerical reservoir simulation models for estimating the original oil and gas volumes in place and for simulating fluid flow behaviors. At a later stage of the field development, reservoir characterization can also help deciding which recovery techniques need to be used for fluids extraction. In complex media, such as faulted reservoirs, flow behavior predictions within volumes close to faults can be a very challenging issue. During the development plan, it is necessary to determine which types of communication exist between faults or which potential barriers exist for fluid flows. The solving of these issues rests on accurate fault characterization. In most cases, faults are not preserved along reservoir characterization workflows. The memory of the interpreted faults from seismic is not kept during seismic inversion and further interpretation of the result. The goal of our study is at first to integrate a 3D fault network as a priori information into a model-based stratigraphic inversion procedure. Secondly, we apply our methodology on a well-known oil and gas case study over a typical North Sea field (UK Northern North Sea) in order to demonstrate its added value for determining reservoir properties. More precisely, the a priori model is composed of several geological units populated by physical attributes, they are extrapolated from well log data following the deposition mode, but usually a priori model building methods respect neither the 3D fault geometry nor the stratification dips on the fault sides. We address this difficulty by applying an efficient flattening method for each stratigraphic unit in our workflow. Even before seismic inversion, the obtained stratigraphic model has been directly used to model synthetic seismic on our case study. Comparisons between synthetic seismic obtained from our 3D fault network model give much lower residuals than with a "basic" stratigraphic model. Finally, we apply our model-based inversion considering both faulted and non-faulted a priori models. By comparing the rock impedances results obtain in the two cases, we can see a better delineation of the Brent-reservoir compartments by using the 3D faulted a priori model built with our method.

Effect of anisotropy on defect mode peculiarities in chiral liquid crystals

NASA Astrophysics Data System (ADS)

Gevorgyan, A. H.; Oganesyan, K. B.

2018-01-01

The effect of anisotropy on defect mode peculiarities in cholesteric liquid crystals is investigated. The light transmission through the cholesteric liquid crystal layer with an anisotropic layer defect inside is solved by Ambartsumian’s layer addition modified method. Two cases are considered. In the first case, it is assumed that the defect layer is non-absorbing, and the effect of refraction anisotropy on the reflection, relative photonic density of states and the total field intensity produced in the defect layer are studied. In the second case, the defect layer is assumed to be isotropic for refraction and anisotropic for absorption, and the influence of defect layer absorption anisotropy on reflection, absorption, relative photonic density of states and the total field intensity produced in the defect layer are investigated.

Robustness of inflation to inhomogeneous initial conditions

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

Clough, Katy; Lim, Eugene A.; DiNunno, Brandon S.

We consider the effects of inhomogeneous initial conditions in both the scalar field profile and the extrinsic curvature on different inflationary models. In particular, we compare the robustness of small field inflation to that of large field inflation, using numerical simulations with Einstein gravity in 3+1 dimensions. We find that small field inflation can fail in the presence of subdominant gradient energies, suggesting that it is much less robust to inhomogeneities than large field inflation, which withstands dominant gradient energies. However, we also show that small field inflation can be successful even if some regions of spacetime start out inmore » the region of the potential that does not support inflation. In the large field case, we confirm previous results that inflation is robust if the inflaton occupies the inflationary part of the potential. Furthermore, we show that increasing initial scalar gradients will not form sufficiently massive inflation-ending black holes if the initial hypersurface is approximately flat. Finally, we consider the large field case with a varying extrinsic curvature K , such that some regions are initially collapsing. We find that this may again lead to local black holes, but overall the spacetime remains inflationary if the spacetime is open, which confirms previous theoretical studies.« less

Investigating nurse practitioners in the private sector: a theoretically informed research protocol.

PubMed

Adams, Margaret; Gardner, Glenn; Yates, Patsy

2017-06-01

To report a study protocol and the theoretical framework normalisation process theory that informs this protocol for a case study investigation of private sector nurse practitioners. Most research evaluating nurse practitioner service is focused on public, mainly acute care environments where nurse practitioner service is well established with strong structures for governance and sustainability. Conversely, there is lack of clarity in governance for emerging models in the private sector. In a climate of healthcare reform, nurse practitioner service is extending beyond the familiar public health sector. Further research is required to inform knowledge of the practice, operational framework and governance of new nurse practitioner models. The proposed research will use a multiple exploratory case study design to examine private sector nurse practitioner service. Data collection includes interviews, surveys and audits. A sequential mixed method approach to analysis of each case will be conducted. Findings from within-case analysis will lead to a meta-synthesis across all four cases to gain a holistic understanding of the cases under study, private sector nurse practitioner service. Normalisation process theory will be used to guide the research process, specifically coding and analysis of data using theory constructs and the relevant components associated with those constructs. This article provides a blueprint for the research and describes a theoretical framework, normalisation process theory in terms of its flexibility as an analytical framework. Consistent with the goals of best research practice, this study protocol will inform the research community in the field of primary health care about emerging research in this field. Publishing a study protocol ensures researcher fidelity to the analysis plan and supports research collaboration across teams. © 2016 John Wiley & Sons Ltd.

Influence of the configuration of the magnetic filter field on the discharge structure in the RF driven negative ion source prototype for fusion

NASA Astrophysics Data System (ADS)

Lishev, S.; Schiesko, L.; Wünderlich, D.; Fantz, U.

2017-08-01

The study provides results for the influence of the filter field topology on the plasma parameters in the RF prototype negative ion source for ITER NBI. A previously developed 2D fluid plasma model of the prototype source was extended towards accounting for the particles and energy losses along the magnetic field lines and the presence of a magnetic field in the driver which is the case at the BATMAN and ELISE test-beds. The effect of the magnetic field in the driver is shown for the magnetic field configuration of the prototype source (i.e. a magnetic field produced by an external magnet frame) by comparison of plasma parameters without and with the magnetic field in the driver and for different axial positions of the filter. Since the ELISE-like magnetic field (i.e. a magnetic field produced by a current flowing through the plasma grid) is a new feature planned to be installed at the BATMAN test-bed, its effect on the discharge structure was studied for different strengths of the magnetic field. The obtained results show for both configurations of the magnetic filter the same main features in the patterns of the plasma parameters in the expansion chamber: a strong axial drop of the electron temperature and the formation of a groove accompanied with accumulation of electrons in front of the plasma grid. The presence of a magnetic field in the driver has a local impact on the plasma parameters: the formation of a second groove of the electron temperature in the case of BATMAN (due to the reversed direction of the filter field in the driver) and a strong asymmetry of the electron density. Accounting for the additional losses in the third dimension suppresses the drifts across the magnetic field and, thus, the variations of the electron density in the expansion chamber are less pronounced.

Hematoporphyrin-mediated photodynamic therapy for treatment of head and neck cancer: clinical update 1996

NASA Astrophysics Data System (ADS)

Schweitzer, Vanessa G.

1996-04-01

From 1983 to 1996 Phase II and III clinical studies at Henry Ford Hospital demonstrated complete or partial responses in 55 of 56 patients treated with hematoporphyrin-derivative or PHOTOFRIN-mediated photodynamic therapy (HPD-PDT) for a variety of benign and malignant upper aerodigestive tract disease: (1) superficial 'condemned mucosa' or 'field cancerization' of the oral cavity and larynx (7 cases); (2) Stage III/IV head and neck cancer (25 cases); (3) mucocutaneous AIDS-associated Kaposi's sarcoma of the upper aerodigestive tract and non AIDS-related Kaposi's sarcoma of the lower extremity (15 cases); (4) recurrent laryngotracheal papillomatosis (3 cases); (5) severe dysplasia/adenocarcinoma or squamous cell carcinoma in situ in Barrett's esophagus (4 cases); (6) partial or completely obstructing terminal esophageal cancer (9 cases). At the time of this report, HPD-PDT produced complete responses in 24 patients (follow up 6 months to 9 years) with 'field cancerization' (CIS, T1N0M0) of the oral cavity and larynx (6 cases), adenocarcinoma in situ in Barrett's esophagus (3 cases), mucocutaneous Kaposi's sarcoma (12 cases), obstructing esophageal carcinoma (1 case), and stage IV squamous cell carcinoma of the nasopharynx (1 case), and radiation therapy or solar-induced basal cell/squamous cell carcinomas (2 cases). PDT treatment protocols, results, complications, and application as adjunct or primary oncologic therapy for head and neck cancer are reviewed in this article.

Causes of forbush decreases and other cosmic ray variations

NASA Technical Reports Server (NTRS)

Barouch, E.; Burlaga, L. F.

1974-01-01

The relationship between neutron monitor variations and the intensity variations of the interplanetary magnetic field is studied, using Deep River data and IMP-series satellite data. In over 80% of the cases studied, identifiable depressions of the cosmic ray intensity are associated with magnetic field enhancements of several hours duration and intensity above 10 gamma. Conversely, each magnetic field enhancement has an identifiable effect (though not necessarily a marked depression) on the cosmic ray intensity. Long lasting Forbush decreases are found to be the consequence of the successive action of several such features. An explanation is presented and discussed.

Mechanical Damage of Tympanic Membrane in Relation to Impulse Pressure Waveform – A Study in Chinchillas

PubMed Central

Gan, Rong Z.; Nakmali, Don; Ji, Xiao D.; Leckness, Kegan; Yokell, Zachary

2016-01-01

Mechanical damage to middle ear components in blast exposure directly causes hearing loss, and the rupture of the tympanic membrane (TM) is the most frequent injury of the ear. However, it is unclear how the severity of injury graded by different patterns of TM rupture is related to the overpressure waveforms induced by blast waves. In the present study, the relationship between the TM rupture threshold and the impulse or overpressure waveform has been investigated in chinchillas. Two groups of animals were exposed to blast overpressure simulated in our lab under two conditions: open field and shielded with a stainless steel cup covering the animal head. Auditory brainstem response (ABR) and wideband tympanometry were measured before and after exposure to check the hearing threshold and middle ear function. Results show that waveforms recorded in the shielded case were different from those in the open field and the TM rupture threshold in the shielded case was lower than that in the open field (3.4±0.7 vs. 9.1±1.7 psi or 181±1.6 vs. 190±1.9 dB SPL). The impulse pressure energy spectra analysis of waveforms demonstrates that the shielded waveforms include greater energy at high frequencies than that of the open field waves. Finally, a 3D finite element (FE) model of the chinchilla ear was used to compute the distributions of stress in the TM and the TM displacement with impulse pressure waves. The FE model-derived change of stress in response to pressure loading in the shielded case was substantially faster than that in the open case. This finding provides the biomechanical mechanisms for blast induced TM damage in relation to overpressure waveforms. The TM rupture threshold difference between the open and shielded cases suggests that an acoustic role of helmets may exist, intensifying ear injury during blast exposure. PMID:26807796

Exposure to magnetic fields among electrical workers in relation to leukemia risk in Los Angeles County.

PubMed

London, S J; Bowman, J D; Sobel, E; Thomas, D C; Garabrant, D H; Pearce, N; Bernstein, L; Peters, J M

1994-07-01

To address the hypotheses that electrical workers are exposed to higher magnetic fields and are at higher risk of leukemia than nonelectrical workers, we performed a registry-based case-control study among men aged 20-64 years with known occupation who were diagnosed with cancer in Los Angeles County between 1972 and 1990. Controls were men with cancers other than those of the central nervous system or leukemia. Magnetic field measurements on workers in each electrical occupation and in a random sample of occupations presumed to be nonelectrical were used to estimate magnetic field exposures for each occupation. Among men in electrical occupations, 121 leukemias were diagnosed. With the exception of electrical engineers, magnetic field exposures were higher among workers in electrical occupations than in nonelectrical occupations. A weakly positive trend in leukemia risk across average occupational magnetic field exposure was observed (odds ratio [OR] per 10 milligauss increase in average magnetic field = 1.2, 95% confidence interval [CI] 1.0-1.5). A slightly stronger association was observed for chronic myloid leukemia, although only 28 cases occurred among electrical workers (OR 10 milligauss increase = 1.6, 95% CI = 1.2-2.0). The results were not materially altered by adjustment for exposure to several agents known or suspected to cause leukemia. Although not conclusive, these results are consistent with findings from studies based on job title alone that electrical workers may be at slightly increased risk of leukemia.

The protective rate of the feline immunodeficiency virus vaccine: An Australian field study.

PubMed

Westman, M E; Malik, R; Hall, E; Harris, M; Norris, J M

2016-09-07

A case-control field study was undertaken to determine the level of protection conferred to client-owned cats in Australia against feline immunodeficiency virus (FIV) using a commercial vaccine. 440 cats with outdoor access from five Australian states/territories underwent testing, comprising 139 potential cases (complete course of primary FIV vaccinations and annual boosters for three or more years), and 301 potential controls (age, sex and postcode matched FIV-unvaccinated cats). FIV status was determined using a combination of antibody testing (using point-of-care test kits) and nucleic acid amplification, as well as virus isolation in cases where results were discordant and in all suspected FIV-vaccinated/FIV-infected cats ('vaccine breakthroughs'). Stringent inclusion criteria were applied to both 'cases' and 'controls'; 89 FIV-vaccinated cats and 212 FIV-unvaccinated cats ultimately satisfied the inclusion criteria. Five vaccine breakthroughs (5/89; 6%), and 25 FIV-infected controls (25/212; 12%) were identified, giving a vaccine protective rate of 56% (95% CI -20 to 84). The difference in FIV prevalence rates between the two groups was not significant (P=0.14). Findings from this study raise doubt concerning the efficacy of Fel-O-Vax FIV® under field conditions. Screening for FIV infection may be prudent before annual FIV re-vaccination and for sick FIV-vaccinated cats. Owners should not rely on vaccination alone to protect cats against the risk of acquiring FIV infection; other measures such as cat curfews, the use of 'modular pet parks' or keeping cats exclusively indoors, are recommended. Copyright © 2016. Published by Elsevier Ltd.

Database architecture and query structures for probe data processing.

DOT National Transportation Integrated Search

2012-03-01

This report summarizes findings and implementations of probe vehicle data collection based on Bluetooth MAC address matching technology. Probe vehicle travel time data are studied in the following field deployment case studies: analysis of traffic ch...

Euclidean mirrors: enhanced vacuum decay from reflected instantons

NASA Astrophysics Data System (ADS)

Akal, Ibrahim; Moortgat-Pick, Gudrid

2018-05-01

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

Developing a Satellite Based Automatic System for Crop Monitoring: Kenya's Great Rift Valley, A Case Study

NASA Astrophysics Data System (ADS)

Lucciani, Roberto; Laneve, Giovanni; Jahjah, Munzer; Mito, Collins

2016-08-01

The crop growth stage represents essential information for agricultural areas management. In this study we investigate the feasibility of a tool based on remotely sensed satellite (Landsat 8) imagery, capable of automatically classify crop fields and how much resolution enhancement based on pan-sharpening techniques and phenological information extraction, useful to create decision rules that allow to identify semantic class to assign to an object, can effectively support the classification process. Moreover we investigate the opportunity to extract vegetation health status information from remotely sensed assessment of the equivalent water thickness (EWT). Our case study is the Kenya's Great Rift valley, in this area a ground truth campaign was conducted during August 2015 in order to collect crop fields GPS measurements, leaf area index (LAI) and chlorophyll samples.

A new method for extracting near-surface mass-density anomalies from land-based gravity data, based on a special case of Poisson's PDE at the Earth's surface: A case study of salt diapirs in the south of Iran

NASA Astrophysics Data System (ADS)

AllahTavakoli, Y.; Safari, A.; Ardalan, A.; Bahroudi, A.

2015-12-01

The current research provides a method for tracking near-surface mass-density anomalies via using only land-based gravity data, which is based on a special version of Poisson's Partial Differential Equation (PDE) of the gravitational field at Earth's surface. The research demonstrates how the Poisson's PDE can provide us with a capability to extract the near-surface mass-density anomalies from land-based gravity data. Herein, this version of the Poisson's PDE is mathematically introduced to the Earth's surface and then it is used to develop the new method for approximating the mass-density via derivatives of the Earth's gravitational field (i.e. via the gradient tensor). Herein, the author believes that the PDE can give us new knowledge about the behavior of the Earth's gravitational field at the Earth's surface which can be so useful for developing new methods of Earth's mass-density determination. In a case study, the proposed method is applied to a set of gravity stations located in the south of Iran. The results were numerically validated via certain knowledge about the geological structures in the area of the case study. Also, the method was compared with two standard methods of mass-density determination. All the numerical experiments show that the proposed approach is well-suited for tracking near-surface mass-density anomalies via using only the gravity data. Finally, the approach is also applied to some petroleum exploration studies of salt diapirs in the south of Iran.

Eyewitness identification in actual criminal cases: an archival analysis.

PubMed

Behrman, B W; Davey, S L

2001-10-01

This study analyzed 271 actual police cases in order to address several prevalent issues in the eyewitness literature. Suspect identification (SI) rates were obtained for 289 photographic lineups, 258 field showups, 58 live lineups, and 66 lineup identifications preceded by earlier identifications. SI rates were assessed for 3 levels of extrinsic evidence: no extrinsic evidence, evidence of minimal probative value, and evidence of substantial probative value. The SI rates for the photographic lineups were assessed as a function of delay, same vs. cross-race conditions, witness type, and weapon presence. SI rates declined significantly over time; SI rates were significantly greater for the same-race condition. SI rates were much greater for field showups than photographic lineups, 76% vs. 48%. The SI rates for the field showups did not vary as a function of eyewitness conditions. The relation between confidence and suspect/foil identifications for the live lineups was significant and moderately high. The utility of archival identification studies for eyewitness testimony research is discussed.

Comparison of Flattening Filter (FF) and Flattening-Filter-Free (FFF) 6 MV photon beam characteristics for small field dosimetry using EGSnrc Monte Carlo code

NASA Astrophysics Data System (ADS)

Sangeetha, S.; Sureka, C. S.

2017-06-01

The present study is focused to compare the characteristics of Varian Clinac 600 C/D flattened and unflattened 6 MV photon beams for small field dosimetry using EGSnrc Monte Carlo Simulation since the small field dosimetry is considered to be the most crucial and provoking task in the field of radiation dosimetry. A 6 MV photon beam of a Varian Clinac 600 C/D medical linear accelerator operates with Flattening Filter (FF) and Flattening-Filter-Free (FFF) mode for small field dosimetry were performed using EGSnrc Monte Carlo user codes (BEAMnrc and DOSXYZnrc) in order to calculate the beam characteristics using Educated-trial and error method. These includes: Percentage depth dose, lateral beam profile, dose rate delivery, photon energy spectra, photon beam uniformity, out-of-field dose, surface dose, penumbral dose and output factor for small field dosimetry (0.5×0.5 cm2 to 4×4 cm2) and are compared with magna-field sizes (5×5 cm2 to 40×40 cm2) at various depths. The results obtained showed that the optimized beam energy and Full-width-half maximum value for small field dosimetry and magna-field dosimetry was found to be 5.7 MeV and 0.13 cm for both FF and FFF beams. The depth of dose maxima for small field size deviates minimally for both FF and FFF beams similar to magna-fields. The depths greater than dmax depicts a steeper dose fall off in the exponential region for FFF beams comparing FF beams where its deviations gets increased with the increase in field size. The shape of the lateral beam profiles of FF and FFF beams varies remains similar for the small field sizes less than 4×4 cm2 whereas it varies in the case of magna-fields. Dose rate delivery for FFF beams shows an eminent increase with a two-fold factor for both small field dosimetry and magna-field sizes. The surface dose measurements of FFF beams for small field size were found to be higher whereas it gets lower for magna-fields than FF beam. The amount of out-of-field dose reduction gets increased with the increase in field size. It is also observed that the photon energy spectrum gets increased with the increase in field size for FFF beam mode. Finally, the output factors for FFF beams were relatively quite low for small field sizes than FF beams whereas it gets higher for magna-field sizes. From this study, it is concluded that the FFF beams depicted minimal deviations in the treatment field region irrespective to the normal tissue region for small field dosimetry compared to FF beams. The more prominent result observed from the study is that the shape of the beam profile remains similar for FF and FFF beams in the case of smaller field size that leads to more accurate treatment planning in the case of IMRT (Image-Guided Radiation Therapy), IGAT (Image-Guided Adaptive Radiation Therapy), SBRT (Stereotactic Body Radiation Therapy), SRS (Stereotactic Radio Surgery), and Tomotherapy techniques where homogeneous dose is not necessary. On the whole, the determination of dosimetric beam characteristics of Varian linac machine using Monte Carlo simulation provides accurate dose calculation as the clinical golden data.

Field enhanced graphene based dual hexagonal ring optical antenna for tip-enhanced spectroscopy

NASA Astrophysics Data System (ADS)

Aditya, Rachakonda A. N. S.; Thampy, Anand Sreekantan

2018-05-01

Field enhanced graphene based dual hexagonal ring optical antenna has been designed in IR regime. Outcomes of hexagonal rings with gold and graphene materials and their effect has been studied and analyzed. Graphene based structures are found to have better and enhanced results as compared to that of gold. In addition, a two fold increase in bandwidth (∼30 THz) and cross-section (∼6.00E+06 nm2) has been observed in case of graphene. Field patterns for various tip/corner curvatures are simulated and localized/regional field patterns are justified. The effect of inter ring spacing on absorption cross section has been studied for every 10 nm increase in spacing. This absorption enhancement in addition to field localization makes the current structure feasible for tip enhanced spectroscopy.

Superradiant Instability and Backreaction of Massive Vector Fields around Kerr Black Holes.

PubMed

East, William E; Pretorius, Frans

2017-07-28

We study the growth and saturation of the superradiant instability of a complex, massive vector (Proca) field as it extracts energy and angular momentum from a spinning black hole, using numerical solutions of the full Einstein-Proca equations. We concentrate on a rapidly spinning black hole (a=0.99) and the dominant m=1 azimuthal mode of the Proca field, with real and imaginary components of the field chosen to yield an axisymmetric stress-energy tensor and, hence, spacetime. We find that in excess of 9% of the black hole's mass can be transferred into the field. In all cases studied, the superradiant instability smoothly saturates when the black hole's horizon frequency decreases to match the frequency of the Proca cloud that spontaneously forms around the black hole.

Asymmetric dipolar ring

DOEpatents

Prosandeev, Sergey A.; Ponomareva, Inna V.; Kornev, Igor A.; Bellaiche, Laurent M.

2010-11-16

A device having a dipolar ring surrounding an interior region that is disposed asymmetrically on the ring. The dipolar ring generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar ring in the plane of the ring. The ring may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field.

Geothermally Coupled Well-Based Compressed Air Energy Storage

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

Davidson, Casie L.; Bearden, Mark D.; Horner, Jacob A.

2015-12-20

Previous work by McGrail et al. (2013, 2015) has evaluated the possibility of pairing compressed air energy storage with geothermal resources in lieu of a fossil-fired power generation component, and suggests that such applications may be cost competitive where geology is favorable to siting both the geothermal and CAES components of such a system. Those studies also note that the collocation of subsurface resources that meet both sets of requirements are difficult to find in areas that also offer infrastructure and near- to mid-term market demand for energy storage. This study examines a novel application for the compressed air storagemore » portion of the project by evaluating the potential to store compressed air in disused wells by amending well casings to serve as subsurface pressure vessels. Because the wells themselves would function in lieu of a geologic storage reservoir for the CAES element of the project, siting could focus on locations with suitable geothermal resources, as long as there was also existing wellfield infrastructure that could be repurposed for air storage. Existing wellfields abound in the United States, and with current low energy prices, many recently productive fields are now shut in. Should energy prices remain stagnant, these idle fields will be prime candidates for decommissioning unless they can be transitioned to other uses, such as redevelopment for energy storage. In addition to the nation’s ubiquitous oil and gas fields, geothermal fields, because of their phased production lifetimes, also may offer many abandoned wellbores that could be used for other purposes, often near currently productive geothermal resources. These existing fields offer an opportunity to decrease exploration and development uncertainty by leveraging data developed during prior field characterization, drilling, and production. They may also offer lower-cost deployment options for hybrid geothermal systems via redevelopment of existing well-field infrastructure. This project assessed the technical and economic feasibility of implementing geothermally coupled well-based CAES for grid-scale energy storage. Based on an evaluation of design specifications for a range of casing grades common in U.S. oil and gas fields, a 5-MW CAES project could be supported by twenty to twenty-five 5,000-foot, 7-inch wells using lower-grade casing, and as few as eight such wells for higher-end casing grades. Using this information, along with data on geothermal resources, well density, and potential future markets for energy storage systems, The Geysers geothermal field was selected to parameterize a case study to evaluate the potential match between the proven geothermal resource present at The Geysers and the field’s existing well infrastructure. Based on calculated wellbore compressed air mass, the study shows that a single average geothermal production well could provide enough geothermal energy to support a 15.4-MW (gross) power generation facility using 34 to 35 geothermal wells repurposed for compressed air storage, resulting in a simplified levelized cost of electricity (sLCOE) estimated at 11.2 ¢/kWh (Table S.1). Accounting for the power loss to the geothermal power project associated with diverting geothermal resources for air heating results in a net 2-MW decrease in generation capacity, increasing the CAES project’s sLCOE by 1.8 ¢/kWh.« less

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

Davidson, C L; Bearden, Mark D; Horner, Jacob A

Previous work by McGrail et al. (2013, 2015) has evaluated the possibility of pairing compressed air energy storage with geothermal resources in lieu of a fossil-fired power generation component, and suggests that such applications may be cost competitive where geology is favorable to siting both the geothermal and CAES components of such a system. Those studies also note that the collocation of subsurface resources that meet both sets of requirements are difficult to find in areas that also offer infrastructure and near- to mid-term market demand for energy storage. This study examines a novel application for the compressed air storagemore » portion of the project by evaluating the potential to store compressed air in disused wells by amending well casings to serve as subsurface pressure vessels. Because the wells themselves would function in lieu of a geologic storage reservoir for the CAES element of the project, siting could focus on locations with suitable geothermal resources, as long as there was also existing wellfield infrastructure that could be repurposed for air storage. Existing wellfields abound in the United States, and with current low energy prices, many recently productive fields are now shut in. Should energy prices remain stagnant, these idle fields will be prime candidates for decommissioning unless they can be transitioned to other uses, such as redevelopment for energy storage. In addition to the nation’s ubiquitous oil and gas fields, geothermal fields, because of their phased production lifetimes, also may offer many abandoned wellbores that could be used for other purposes, often near currently productive geothermal resources. These existing fields offer an opportunity to decrease exploration and development uncertainty by leveraging data developed during prior field characterization, drilling, and production. They may also offer lower-cost deployment options for hybrid geothermal systems via redevelopment of existing well-field infrastructure. This project assessed the technical and economic feasibility of implementing geothermally coupled well-based CAES for grid-scale energy storage. Based on an evaluation of design specifications for a range of casing grades common in U.S. oil and gas fields, a 5-MW CAES project could be supported by twenty to twenty-five 5,000-foot, 7-inch wells using lower-grade casing, and as few as eight such wells for higher-end casing grades. Using this information, along with data on geothermal resources, well density, and potential future markets for energy storage systems, The Geysers geothermal field was selected to parameterize a case study to evaluate the potential match between the proven geothermal resource present at The Geysers and the field’s existing well infrastructure. Based on calculated wellbore compressed air mass, the study shows that a single average geothermal production well could provide enough geothermal energy to support a 15.4-MW (gross) power generation facility using 34 to 35 geothermal wells repurposed for compressed air storage, resulting in a simplified levelized cost of electricity (sLCOE) estimated at 11.2 ¢/kWh (Table S.1). Accounting for the power loss to the geothermal power project associated with diverting geothermal resources for air heating results in a net 2-MW decrease in generation capacity, increasing the CAES project’s sLCOE by 1.8 ¢/kWh.« less

An Indexing Coverage Study of Toxicological Literature

ERIC Educational Resources Information Center

Montgomery, Ruth Reinke

1973-01-01

The goal of this study was an appraisal of indexing coverage for the interdisciplinary field of toxicology. Information of research significance was limited to primary literature, defined as published documents containing original data from experimental work or case studies. (6 references) (Author/NH)

Role of coherent structures in supersonic impinging jetsa)

NASA Astrophysics Data System (ADS)

Kumar, Rajan; Wiley, Alex; Venkatakrishnan, L.; Alvi, Farrukh

2013-07-01

This paper describes the results of a study examining the flow field and acoustic characteristics of a Mach 1.5 ideally expanded supersonic jet impinging on a flat surface and its control using steady microjets. Emphasis is placed on two conditions of nozzle to plate distances (h/d), of which one corresponds to where the microjet based active flow control is very effective in reducing flow unsteadiness and near-field acoustics and the other has minimal effectiveness. Measurements include unsteady pressures, nearfield acoustics using microphone and particle image velocimetry. The nearfield noise and unsteady pressure spectra at both h/d show discrete high amplitude impinging tones, which in one case (h/d = 4) are significantly reduced with control but in the other case (h/d = 4.5) remain unaffected. The particle image velocimetry measurements, both time-averaged and phase-averaged, were used to better understand the basic characteristics of the impinging jet flow field especially the role of coherent vortical structures in the noise generation and control. The results show that the flow field corresponding to the case of least control effectiveness comprise well defined, coherent, and symmetrical vortical structures and may require higher levels of microjet pressure supply for noise suppression when compared to the flow field more responsive to control (h/d = 4) which shows less organized, competing (symmetrical and helical) instabilities.

Carbon dioxide field flooding: a retrospective study.

PubMed

Frados, A

2001-05-01

The carbon dioxide surgical field flooding technique has long been tried with varying degrees of success. A recent revival of the technique that began over 40 years ago in cardiac surgery, has brought promise as well as improved results attributable to improved technology. Studies at JFK Medical Center have been very successful using the carbon dioxide surgical field-flooding technique. Establishing new guidelines will assist other institutions in attempting this "old" technique with renewed success. Modern, more efficient equipment make use of carbon dioxide to displace intracardiac gases a safe procedure. The carbon dioxide field-flooding technique is safer, easier, and more efficacious than traditional de-airing techniques. This study shows that a long-standing procedure is valuable by observing the results, and, retrospectively evaluating stroke rates among cardiac valve cases at the hospital.

The PAC-MAN model: Benchmark case for linear acoustics in computational physics

NASA Astrophysics Data System (ADS)

Ziegelwanger, Harald; Reiter, Paul

2017-10-01

Benchmark cases in the field of computational physics, on the one hand, have to contain a certain complexity to test numerical edge cases and, on the other hand, require the existence of an analytical solution, because an analytical solution allows the exact quantification of the accuracy of a numerical simulation method. This dilemma causes a need for analytical sound field formulations of complex acoustic problems. A well known example for such a benchmark case for harmonic linear acoustics is the ;Cat's Eye model;, which describes the three-dimensional sound field radiated from a sphere with a missing octant analytically. In this paper, a benchmark case for two-dimensional (2D) harmonic linear acoustic problems, viz., the ;PAC-MAN model;, is proposed. The PAC-MAN model describes the radiated and scattered sound field around an infinitely long cylinder with a cut out sector of variable angular width. While the analytical calculation of the 2D sound field allows different angular cut-out widths and arbitrarily positioned line sources, the computational cost associated with the solution of this problem is similar to a 1D problem because of a modal formulation of the sound field in the PAC-MAN model.

A rare case of respiratory disorders associated with two autosomal recessive diseases and male infertility.

PubMed

Mendeluk, Gabriela Ruth; Costa, Sergio López; Scigliano, Sergio; Menga, Guillermo; Demiceu, Sergio; Palaoro, Luis Alberto

2013-01-01

The study of nasal ciliary beat frequency (CBF) and ultrastructure may contribute to the understanding of pathognomonic cases of male infertility associated with defects in sperm motility. This study was designed to report a particular case of male infertility, characterized by the association of two respiratory autosomal recessive genetic diseases (alpha-1-antitrypsin deficiency [AAT-D] and primary ciliary dyskinesia [PCD]). A 39-year-old patient with complete sperm immotility, AAT-D, and bronchiectasis was studied in the Laboratory of Male Fertility, the Department of Urology, the Respiratory Center of a Pediatric Hospital, and in the Department of Clinical Medicine of a Rehabilitation Respiratory Hospital. Family history, physical examination, hormonal analysis, microbial assays, semen analysis, nasal ciliary function, and structure study by digital high-speed video photography and transmission electron microscopy are described. A noninvasive nasal biopsy to retrieve ciliated epithelium lining the inferior surface of the inferior nasal turbinates was performed and CBF was determined. Beat pattern was slightly curved and rigid, not wide, and metacronic in all the observed fields analyzed. CBF was 8.2 Hz in average (reference value, 10-15 Hz) Ultrastructural assay revealed absence of the inner dynein arms in 97% of the cilia observed. The final infertility accurate diagnosis was achieved by the study of nasal CBF and ultrastructure contributing to the patient health management and genetic counseling while deciding fatherhood. Beyond this particular case, the present report may open a new field of studies in male infertility, mainly in cases of asthenozoospermia.

A rare case of respiratory disorders associated with two autosomal recessive diseases and male infertility

PubMed Central

Costa, Sergio López; Scigliano, Sergio; Menga, Guillermo; Demiceu, Sergio; Palaoro, Luis Alberto

2013-01-01

The study of nasal ciliary beat frequency (CBF) and ultrastructure may contribute to the understanding of pathognomonic cases of male infertility associated with defects in sperm motility. This study was designed to report a particular case of male infertility, characterized by the association of two respiratory autosomal recessive genetic diseases (alpha-1-antitrypsin deficiency [AAT-D] and primary ciliary dyskinesia [PCD]). A 39-year-old patient with complete sperm immotility, AAT-D, and bronchiectasis was studied in the Laboratory of Male Fertility, the Department of Urology, the Respiratory Center of a Pediatric Hospital, and in the Department of Clinical Medicine of a Rehabilitation Respiratory Hospital. Family history, physical examination, hormonal analysis, microbial assays, semen analysis, nasal ciliary function, and structure study by digital high-speed video photography and transmission electron microscopy are described. A noninvasive nasal biopsy to retrieve ciliated epithelium lining the inferior surface of the inferior nasal turbinates was performed and CBF was determined. Beat pattern was slightly curved and rigid, not wide, and metacronic in all the observed fields analyzed. CBF was 8.2 Hz in average (reference value, 10–15 Hz) Ultrastructural assay revealed absence of the inner dynein arms in 97% of the cilia observed. The final infertility accurate diagnosis was achieved by the study of nasal CBF and ultrastructure contributing to the patient health management and genetic counseling while deciding fatherhood. Beyond this particular case, the present report may open a new field of studies in male infertility, mainly in cases of asthenozoospermia. PMID:23772318

Social Service Professionals' Perceptions of Nonoffending Caregivers in Child Sexual Abuse Cases

ERIC Educational Resources Information Center

Wolfteich, Paula M.; Cline, Monica L.

2013-01-01

This study was designed to assess social service workers' perceptions of nonoffending caregivers in cases of child sexual abuse. Attributions of blame were examined by administering questionnaires to staff at local social service agencies. It was hypothesized that social service workers who worked in the field longer, were male, or had less…

College Student Perceptions and Learning Points from the Formal University Judicial Process: A Multiple Case Study

ERIC Educational Resources Information Center

Lucas, Christopher M.

2009-01-01

For educators in the field of higher education and judicial affairs, issues are growing. Campus adjudicators must somehow maximize every opportunity for student education and development in the context of declining resources and increasing expectations of public accountability. Numbers of student misconduct cases, including matters of violence and…

Voices from the Field: Evaluation as Part of a Learning Culture

ERIC Educational Resources Information Center

Hoole, Emily; Patterson, Tracy E.

2008-01-01

The authors present the argument that evaluation as currently practiced is failing the needs of the social sector, if the goal is to help organizations achieve their mission. Three case studies are presented in which evaluation played a key role in the development of a learning culture within the organization. Each case highlights the positive…

Global Education and the Cooperation of NGOs and Schools: A German Case Study

ERIC Educational Resources Information Center

Bergmüller, Claudia

2016-01-01

In recent years, there has been growing pressure but also an increase of possibilities for non-governmental organizations (NGOs) to cooperate with schools in the field of global education. However, especially in cases of more continuous forms of cooperation, difficulties in process management are noted and the intended cooperation impacts often…

Toward Integrating Environmental and Economic Education: Lessons from the U.S. Acid Rain Program

ERIC Educational Resources Information Center

Ellerbrock, Michael J.; Regn, Ann M.

2004-01-01

This field report presents an actual case study which illustrates that the natural and social sciences, in this case ecology and economics, can and should be integrated in environmental education and the formulation of public policy. After outlining basic economic approaches for addressing environmental problems, we focus on the process and…

Method Apparatus And System For Detecting Seismic Waves In A Borehole

DOEpatents

West, Phillip B.; Sumstine, Roger L.

2006-03-14

A method, apparatus and system for detecting seismic waves. A sensing apparatus is deployed within a bore hole and may include a source magnet for inducing a magnetic field within a casing of the borehole. An electrical coil is disposed within the magnetic field to sense a change in the magnetic field due to a displacement of the casing. The electrical coil is configured to remain substantially stationary relative to the well bore and its casing along a specified axis such that displacement of the casing induces a change within the magnetic field which may then be sensed by the electrical coil. Additional electrical coils may be similarly utilized to detect changes in the same or other associated magnetic fields along other specified axes. The additional sensor coils may be oriented substantially orthogonally relative to one another so as to detect seismic waves along multiple orthogonal axes in three dimensional space.

More about arc-polarized structures in the solar wind

NASA Astrophysics Data System (ADS)

Haaland, S.; Sonnerup, B.; Paschmann, G.

2012-05-01

We report results from a Cluster-based study of the properties of 28 arc-polarized magnetic structures (also called rotational discontinuities) in the solar wind. These Alfvénic events were selected from the database created and analyzed by Knetter (2005) by use of criteria chosen to eliminate ambiguous cases. His studies showed that standard, four-spacecraft timing analysis in most cases lacks sufficient accuracy to identify the small normal magnetic field components expected to accompany such structures, leaving unanswered the question of their existence. Our study aims to break this impasse. By careful application of minimum variance analysis of the magnetic field (MVAB) from each individual spacecraft, we show that, in most cases, a small but significantly non-zero magnetic field component was present in the direction perpendicular to the discontinuity. In the very few cases where this component was found to be large, examination revealed that MVAB had produced an unusual and unexplained orientation of the normal vector. On the whole, MVAB shows that many verifiable rotational discontinuities (Bn ≠ 0) exist in the solar wind and that their eigenvalue ratio (EVR = intermediate/minimum variance) can be extremely large (up to EVR = 400). Each of our events comprises four individual spacecraft crossings. The events include 17 ion-polarized cases and 11 electron-polarized ones. Fifteen of the ion events have widths ranging from 9 to 21 ion inertial lengths, with two outliers at 46 and 54. The electron-polarized events are generally thicker: nine cases fall in the range 20-71 ion inertial lengths, with two outliers at 9 and 13. In agreement with theoretical predictions from a one-dimensional, ideal, Hall-MHD description (Sonnerup et al., 2010), the ion-polarized events show a small depression in field magnitude, while the electron-polarized ones tend to show a small enhancement. This effect was also predicted by Wu and Lee (2000). Judging only from the sense of the plasma flow across our DDs, their propagation appears to be sunward as often as anti-sunward. However, we argue that this result can be misleading as a consequence of the possible presence of magnetic islands within the DDs. How the rotational discontinuities come into existence, how they evolve with time, and what roles they play in the solar wind remain open questions.

3D non-linear inversion of magnetic anomalies caused by prismatic bodies using differential evolution algorithm

NASA Astrophysics Data System (ADS)

Balkaya, Çağlayan; Ekinci, Yunus Levent; Göktürkler, Gökhan; Turan, Seçil

2017-01-01

3D non-linear inversion of total field magnetic anomalies caused by vertical-sided prismatic bodies has been achieved by differential evolution (DE), which is one of the population-based evolutionary algorithms. We have demonstrated the efficiency of the algorithm on both synthetic and field magnetic anomalies by estimating horizontal distances from the origin in both north and east directions, depths to the top and bottom of the bodies, inclination and declination angles of the magnetization, and intensity of magnetization of the causative bodies. In the synthetic anomaly case, we have considered both noise-free and noisy data sets due to two vertical-sided prismatic bodies in a non-magnetic medium. For the field case, airborne magnetic anomalies originated from intrusive granitoids at the eastern part of the Biga Peninsula (NW Turkey) which is composed of various kinds of sedimentary, metamorphic and igneous rocks, have been inverted and interpreted. Since the granitoids are the outcropped rocks in the field, the estimations for the top depths of two prisms representing the magnetic bodies were excluded during inversion studies. Estimated bottom depths are in good agreement with the ones obtained by a different approach based on 3D modelling of pseudogravity anomalies. Accuracy of the estimated parameters from both cases has been also investigated via probability density functions. Based on the tests in the present study, it can be concluded that DE is a useful tool for the parameter estimation of source bodies using magnetic anomalies.

Influence of vorticity distribution on singularities in linearized supersonic flow

NASA Astrophysics Data System (ADS)

Gopal, Vijay; Maddalena, Luca

2018-05-01

The linearized steady three-dimensional supersonic flow can be analyzed using a vector potential approach which transforms the governing equation to a standard form of two-dimensional wave equation. Of particular interest are the canonical horseshoe line-vortex distribution and the resulting induced velocity field in supersonic flow. In this case, the singularities are present at the vortex line itself and also at the surface of the cone of influence originating from the vertices of the horseshoe structure. This is a characteristic of the hyperbolic nature of the flow which renders the study of supersonic vortex dynamics a challenging task. It is conjectured in this work that the presence of the singularity at the cone of influence is associated with the step-function nature of the vorticity distribution specified in the canonical case. At the phenomenological level, if one considers the three-dimensional steady supersonic flow, then a sudden appearance of a line-vortex will generate a ripple of singularities in the induced velocity field which convect downstream and laterally spread, at the most, to the surface of the cone of influence. Based on these findings, this work includes an exploration of potential candidates for vorticity distributions that eliminate the singularities at the cone of influence. The analysis of the resulting induced velocity field is then compared with the canonical case, and it is observed that the singularities were successfully eliminated. The manuscript includes an application of the proposed method to study the induced velocity field in a confined supersonic flow.

Numerical simulations of tropical cyclones with assimilation of satellite, radar and in-situ observations: lessons learned from recent field programs and real-time experimental forecasts

NASA Astrophysics Data System (ADS)

Pu, Z.; Zhang, L.

2010-12-01

The impact of data assimilation on the predictability of tropical cyclones is examined with the cases from recent field programs and real-time hurricane forecast experiments. Mesoscale numerical simulations are performed to simulate major typhoons during the T-PARC/TCS08 field campaign with the assimilation of satellite, radar and in-situ observations. Results confirmed that data assimilation has indeed resulted in improved numerical simulations of tropical cyclones. However, positive impacts from the satellite and radar data are strongly depend on the quality of these data. Specifically, it is found that the overall impacts of assimilating AIRS retrieved atmospheric temperature and moisture profiles on numerical simulations of tropical cyclones are very sensitive to the bias corrections of the data.For instance, the dry biases of moisture profiles can cause the decay of tropical cyclones in the numerical simulations.In addition, the quality of airborne Doppler radar data has strong influence on numerical simulations of tropical cyclones in terms of their track, intensity and precipitation structures. Outcomes from assimilating radar data with various quality thresholds suggest that a trade-off between the quality and area coverage of the radar data is necessary in the practice. Some of those experiences obtained from the field case studies are applied to the near-real time experimental hurricane forecasts during the 2010 hurricane season. Results and issues raised from the case studies and real-time experiments will be discussed.

[Central nervous system dysgerminoma: a clinicopathological study of 3 cases].

PubMed

Bellil, Selma; Braham, Emna; Limaiem, Faten; Bellil, Khadija; Chelly, Ines; Mekni, Amina; Haouet, Slim; Zitouna, Moncef; Jemel, Hafedh; Khaldi, Moncef; Kchir, Nidhameddine

2009-03-01

Intracranial germ cell tumors are rarely seen and typically localize in the pineal or suprasellar region. The largest category of germ cell tumors is dysgerminoma. to describe clinicopathological features and immunohistochemical profile of dysgerminomas. We report three cases of central nervous system dysgerminomas. There were two young women and a man who were 6, 11 and 23-year-old. They presented with symptoms of insipidus diabetes (n=3) with association to visual field defects in the third case. Radiological findings showed a supra seller lesion in two cases. Double localization in the pineal and suprasellar regions was seen in the third case. Histologic examination and immunohistochemical study of surgical specimen were consistent with primary central nervous system dysgerminoma.

Investigation on the effects of temperature dependency of material parameters on a thermoelastic loading problem

NASA Astrophysics Data System (ADS)

Kumar, Anil; Mukhopadhyay, Santwana

2017-08-01

The present work is concerned with the investigation of thermoelastic interactions inside a spherical shell with temperature-dependent material parameters. We employ the heat conduction model with a single delay term. The problem is studied by considering three different kinds of time-dependent temperature and stress distributions applied at the inner and outer surfaces of the shell. The problem is formulated by considering that the thermal properties vary as linear function of temperature that yield nonlinear governing equations. The problem is solved by applying Kirchhoff transformation along with integral transform technique. The numerical results of the field variables are shown in the different graphs to study the influence of temperature-dependent thermal parameters in various cases. It has been shown that the temperature-dependent effect is more prominent in case of stress distribution as compared to other fields and also the effect is significant in case of thermal shock applied at the two boundary surfaces of the spherical shell.

Influence of alignment errors of a telescope system on its aberration field

NASA Astrophysics Data System (ADS)

Shack, R. V.; Thompson, K.

1980-01-01

The study of aberrations in a system is considered. It is pointed out that a system in which the elements are tilted and decentered has no axial symmetry, and in fact no symmetry at all if the tilts, and decentrations are not coplanar. It is customary in such a case to give up on an aberration-theoretic treatment and simply trace enough rays to produce a set of spot diagrams for various points in the field. However, in connection with the lack of symmetry, it is necessary to select a relatively large number of points. The considered investigation is concerned with an aberration-theoretic approach which can be applied to such systems. This approach provides insight into the field behavior of the aberrations with great economy in the calculation. It is based on a concept suggested by Buchroeder (1976). In the given case, this concept considers for the component fields corresponding to the various surfaces centers of symmetry which do not coincide. Attention is given to the procedure for locating the centers of symmetry, aberrations fields, spherical aberration, and various types of astigmatism.

Dimensional reduction as a method to obtain dual theories for massive spin two in arbitrary dimensions

NASA Astrophysics Data System (ADS)

Khoudeir, A.; Montemayor, R.; Urrutia, Luis F.

2008-09-01

Using the parent Lagrangian method together with a dimensional reduction from D to (D-1) dimensions, we construct dual theories for massive spin two fields in arbitrary dimensions in terms of a mixed symmetry tensor TA[A1A2…AD-2]. Our starting point is the well-studied massless parent action in dimension D. The resulting massive Stueckelberg-like parent actions in (D-1) dimensions inherit all the gauge symmetries of the original massless action and can be gauge fixed in two alternative ways, yielding the possibility of having a parent action with either a symmetric or a nonsymmetric Fierz-Pauli field eAB. Even though the dual sector in terms of the standard spin two field includes only the symmetrical part e{AB} in both cases, these two possibilities yield different results in terms of the alternative dual field TA[A1A2…AD-2]. In particular, the nonsymmetric case reproduces the Freund-Curtright action as the dual to the massive spin two field action in four dimensions.

[Landscape character assessment framework in rural area: A case study in Qiaokou, Chang-sha, China].

PubMed

Zhang, Qian; Liu, Wen-ping; Yu, Zhen-rong

2015-05-01

Based on the concept and methods of landscape character assessment (LCA) in England, this paper applied a complete process of landscape character assessment with a case study in Qiaokou Town, which is located in a typical southern paddy fields area in Changsha City. We drew the landscape character map of Qiaokou Town through desk classification and field survey, identified and compared the key characters of each character area, and proposed suggestions on the improvement and stewardship of landscape characters. The results showed that Qiaokou could be divided into 2 landscape character types and 7 landscape character areas with the main differences in cropland and vegetation pattern as well as aesthetic characters. The case study indicated that LCA could be a critical tool to identify the characteristics in rural area, and provide helpful guidance to protect, restore and maintain the unique culture and characters of rural landscape, which is useful for targeted rural landscape development. In the future, we suggested that the assessment on the effects of landscape construction measures on the ecosystem services should be incorporated in LCA research as well.

Field-based optimal-design of an electric motor: a new sensitivity formulation

NASA Astrophysics Data System (ADS)

Barba, Paolo Di; Mognaschi, Maria Evelina; Lowther, David Alister; Wiak, Sławomir

2017-12-01

In this paper, a new approach to robust optimal design is proposed. The idea is to consider the sensitivity by means of two auxiliary criteria A and D, related to the magnitude and isotropy of the sensitivity, respectively. The optimal design of a switched-reluctance motor is considered as a case study: since the case study exhibits two design criteria, the relevant Pareto front is approximated by means of evolutionary computing.

Multiloop amplitudes of light-cone gauge superstring field theory: odd spin structure contributions

NASA Astrophysics Data System (ADS)

Ishibashi, Nobuyuki; Murakami, Koichi

2018-03-01

We study the odd spin structure contributions to the multiloop amplitudes of light-cone gauge superstring field theory. We show that they coincide with the amplitudes in the conformal gauge with two of the vertex operators chosen to be in the pictures different from the standard choice, namely (-1, -1) picture in the type II case and -1 picture in the heterotic case. We also show that the contact term divergences can be regularized in the same way as in the amplitudes for the even structures and we get the amplitudes which coincide with those obtained from the first-quantized approach.

Risk of hematological malignancies associated with magnetic fields exposure from power lines: a case-control study in two municipalities of northern Italy.

PubMed

Malagoli, Carlotta; Fabbi, Sara; Teggi, Sergio; Calzari, Mariagiulia; Poli, Maurizio; Ballotti, Elena; Notari, Barbara; Bruni, Maurizio; Palazzi, Giovanni; Paolucci, Paolo; Vinceti, Marco

2010-03-30

Some epidemiologic studies have suggested an association between electromagnetic field exposure induced by high voltage power lines and childhood leukemia, but null results have also been yielded and the possibility of bias due to unmeasured confounders has been suggested. We studied this relation in the Modena and Reggio Emilia municipalities of northern Italy, identifying the corridors along high voltage power lines with calculated magnetic field intensity in the 0.1-<0.2, 0.2-<0.4, and > or = 0.4 microTesla ranges. We identified 64 cases of newly-diagnosed hematological malignancies in children aged <14 within these municipalities from 1986 to 2007, and we sampled four matched controls for each case, collecting information on historical residence and parental socioeconomic status of these subjects. Relative risk of leukemia associated with antecedent residence in the area with exposure > or = 0.1 microTesla was 3.2 (6.7 adjusting for socioeconomic status), but this estimate was statistically very unstable, its 95% confidence interval being 0.4-23.4, and no indication of a dose-response relation emerged. Relative risk for acute lymphoblastic leukemia was 5.3 (95% confidence interval 0.7-43.5), while there was no increased risk for the other hematological malignancies. Though the number of exposed children in this study was too low to allow firm conclusions, results were more suggestive of an excess risk of leukemia among exposed children than of a null relation.

Barriers to community case management of malaria in Saraya, Senegal: training, and supply-chains.

PubMed

Blanas, Demetri A; Ndiaye, Youssoupha; Nichols, Kim; Jensen, Andrew; Siddiqui, Ammar; Hennig, Nils

2013-03-14

Health workers in sub-Saharan Africa can now diagnose and treat malaria in the field, using rapid diagnostic tests and artemisinin-based combination therapy in areas without microscopy and widespread resistance to previously effective drugs. This study evaluates communities' perceptions of a new community case management of malaria programme in the district of Saraya, south-eastern Senegal, the effectiveness of lay health worker trainings, and the availability of rapid diagnostic tests and artemisinin-based combination therapy in the field. The study employed qualitative and quantitative methods including focus groups with villagers, and pre- and post-training questionnaires with lay health workers. Communities approved of the community case management programme, but expressed concern about other general barriers to care, particularly transportation challenges. Most lay health workers acquired important skills, but a sizeable minority did not understand the rapid diagnostic test algorithm and were not able to correctly prescribe arteminisin-based combination therapy soon after the training. Further, few women lay health workers participated in the programme. Finally, the study identified stock-outs of rapid tests and anti-malaria medication products in over half of the programme sites two months after the start of the programme, thought due to a regional shortage. This study identified barriers to implementation of the community case management of malaria programme in Saraya that include lay health worker training, low numbers of women participants, and generalized stock-outs. These barriers warrant investigation into possible solutions of relevance to community case management generally.

The population ecology of infectious diseases: pertussis in Thailand as a case study.

PubMed

Blackwood, J C; Cummings, D A T; Broutin, H; Iamsirithaworn, S; Rohani, P

2012-12-01

Many of the fundamental concepts in studying infectious diseases are rooted in population ecology. We describe the importance of population ecology in exploring central issues in infectious disease research including identifying the drivers and dynamics of host-pathogen interactions and pathogen persistence, and evaluating the success of public health policies. The use of ecological concepts in infectious disease research is demonstrated with simple theoretical examples in addition to an analysis of case notification data of pertussis, a childhood respiratory disease, in Thailand as a case study. We stress that further integration of these fields will have significant impacts in infectious diseases research.

Dipole interaction of the Quincke rotating particles.

PubMed

Dolinsky, Yu; Elperin, T

2012-02-01

We study the behavior of particles having a finite electric permittivity and conductivity in a weakly conducting fluid under the action of the external electric field. We consider the case when the strength of the external electric field is above the threshold, and particles rotate due to the Quincke effect. We determine the magnitude of the dipole interaction of the Quincke rotating particles and the shift of frequency of the Quincke rotation caused by the dipole interaction between the particles. It is demonstrated that depending on the mutual orientation of the vectors of angular velocities of particles, vector-directed along the straight line between the centers of the particles and the external electric field strength vector, particles can attract or repel each other. In contrast to the case of nonrotating particles when the magnitude of the dipole interaction increases with the increase of the strength of the external electric field, the magnitude of the dipole interaction of the Quincke rotating particles either does not change or decreases with the increase of the strength of the external electric field depending on the strength of the external electric field and electrodynamic parameters of the particles.

Dipole interaction of the Quincke rotating particles

NASA Astrophysics Data System (ADS)

Dolinsky, Yu.; Elperin, T.

2012-02-01

We study the behavior of particles having a finite electric permittivity and conductivity in a weakly conducting fluid under the action of the external electric field. We consider the case when the strength of the external electric field is above the threshold, and particles rotate due to the Quincke effect. We determine the magnitude of the dipole interaction of the Quincke rotating particles and the shift of frequency of the Quincke rotation caused by the dipole interaction between the particles. It is demonstrated that depending on the mutual orientation of the vectors of angular velocities of particles, vector-directed along the straight line between the centers of the particles and the external electric field strength vector, particles can attract or repel each other. In contrast to the case of nonrotating particles when the magnitude of the dipole interaction increases with the increase of the strength of the external electric field, the magnitude of the dipole interaction of the Quincke rotating particles either does not change or decreases with the increase of the strength of the external electric field depending on the strength of the external electric field and electrodynamic parameters of the particles.

Numerical characterization of plasma breakdown in reversed field pinches

NASA Astrophysics Data System (ADS)

Peng, Yanli; Zhang, Ya; Mao, Wenzhe; Yang, Zhoujun; Hu, Xiwei; Jiang, Wei

2018-02-01

In the reversed field pinch, there is considerable interest in investigating the plasma breakdown. Indeed, the plasma formed during the breakdown may have an influence on the confinement and maintenance in the latter process. However, up to now there has been no related work, experimentally or in simulation, regarding plasma breakdown in reversed field pinch (RFP). In order to figure out the physical mechanism behind plasma breakdown, the effects of the toroidal and error magnetic field, as well as the loop voltage have been studied. We find that the error magnetic field cannot be neglected even though it is quite small in the short plasma breakdown phase. As the toroidal magnetic field increases, the averaged electron energy is reduced after plasma breakdown is complete, which is disadvantageous for the latter process. In addition, unlike the voltage limits in the tokamak, loop voltages can be quite high because there are no requirements for superconductivity. Volt-second consumption has a small difference under different loop voltages. The breakdown delay still exists in various loop voltage cases, but it is much shorter compared to that in the tokamak case. In all, successful breakdowns are possible in the RFP under a fairly broad range of parameters.

Hypothesis: the risk of childhood leukemia is related to combinations of power-frequency and static magnetic fields.

PubMed

Bowman, J D; Thomas, D C; London, S J; Peters, J M

1995-01-01

We present a hypothesis that the risk of childhood leukemia is related to exposure to specific combinations of static and extremely-low-frequency (ELF) magnetic fields. Laboratory data from calcium efflux and diatom mobility experiments were used with the gyromagnetic equation to predict combinations of 60 Hz and static magnetic fields hypothesized to enhance leukemia risk. The laboratory data predicted 19 bands of the static field magnitude with a bandwidth of 9.1 microT that, together with 60 Hz magnetic fields, are expected to have biological activity. We then assessed the association between this exposure metric and childhood leukemia using data from a case-control study in Los Angeles County. ELF and static magnetic fields were measured in the bedrooms of 124 cases determined from a tumor registry and 99 controls drawn from friends and random digit dialing. Among these subjects, 26 cases and 20 controls were exposed to static magnetic fields lying in the predicted bands of biological activity centered at 38.0 microT and 50.6 microT. Although no association was found for childhood leukemia in relation to measured ELF or static magnetic fields alone, an increasing trend of leukemia risk with measured ELF fields was found for subjects within these static field bands (P for trend = 0.041). The odds ratio (OR) was 3.3 [95% confidence interval (CI) = 0.4-30.5] for subjects exposed to static fields within the derived bands and to ELF magnetic field above 0.30 microT (compared to subjects exposed to static fields outside the bands and ELF magnetic fields below 0.07 microT). When the 60 Hz magnetic fields were assessed according to the Wertheimer-Leeper code for wiring configurations, leukemia risks were again greater with the hypothesized exposure conditions (OR = 9.2 for very high current configurations within the static field bands; 95% CI = 1.3-64.6). Although the risk estimates are based on limited magnetic field measurements for a small number of subjects, these findings suggest that the risk of childhood leukemia may be related to the combined effects of the static and ELF magnetic fields. Further tests of the hypothesis are proposed.

Fermions tunneling from the Horowitz-Strominger Dilaton black hole

NASA Astrophysics Data System (ADS)

Li, Qiang; Zeng, Xiaoxiong

2009-06-01

Based on the work of Kerner and Mann, fermions tunneling from the Horowitz-Strominger Dilaton black hole on the membrane is studied. Owing to the coupling among electromagnetic field, matter field and gravity field, the Dirac equation of charged particles is introduced, and according to that, the expected emission temperature is obtained. After the self-gravitational interaction is considered, it is found that the tunneling rate of fermions also satisfies the underlying Unitary theory as the case of scalar particles.

Geometrical optics in the near field: local plane-interface approach with evanescent waves.

PubMed

Bose, Gaurav; Hyvärinen, Heikki J; Tervo, Jani; Turunen, Jari

2015-01-12

We show that geometrical models may provide useful information on light propagation in wavelength-scale structures even if evanescent fields are present. We apply a so-called local plane-wave and local plane-interface methods to study a geometry that resembles a scanning near-field microscope. We show that fair agreement between the geometrical approach and rigorous electromagnetic theory can be achieved in the case where evanescent waves are required to predict any transmission through the structure.

Vakonomic Constraints in Higher-Order Classical Field Theory

NASA Astrophysics Data System (ADS)

Campos, Cédric M.

2010-07-01

We propose a differential-geometric setting for the dynamics of a higher-order field theory, based on the Skinner and Rusk formalism for mechanics. This approach incorporates aspects of both, the Lagrangian and the Hamiltonian description, since the field equations are formulated using the Lagrangian on a higher-order jet bundle and the canonical multisymplectic form on its affine dual. The result is that we obtain a unique and global intrinsic description of the dynamics. The case of vakonomic constraints is also studied within this formalism.

Entanglement of Dirac fields in an expanding spacetime

NASA Astrophysics Data System (ADS)

Fuentes, Ivette; Mann, Robert B.; Martín-Martínez, Eduardo; Moradi, Shahpoor

2010-08-01

We study the entanglement generated between Dirac modes in a 2-dimensional conformally flat Robertson-Walker universe. We find radical qualitative differences between the bosonic and fermionic entanglement generated by the expansion. The particular way in which fermionic fields get entangled encodes more information about the underlying spacetime than the bosonic case, thereby allowing us to reconstruct the parameters of the history of the expansion. This highlights the importance of bosonic/fermionic statistics to account for relativistic effects on the entanglement of quantum fields.

Lessons Learned from History and Experience: Five Simple Ways to Improve the Efficacy of Sexual Offender Treatment

ERIC Educational Resources Information Center

D'Orazio, Deirdre M.

2013-01-01

This article chronicles the development of the field of Sexual Offender Treatment in the United States since the 1980's. It offers an analysis of the Relapse Prevention model, a case study, and a summary description of contemporary field advancements. Through historical and personal reflection, the author summarizes lessons learned as five…

Scholarly Capacities, Habits of Mind, and Dispositions: Case Studies of Education Doctoral Students in a Dissertation Proposal Seminar

ERIC Educational Resources Information Center

McArthur, Dana Lynn

2011-01-01

The completion of a formal proposal for a dissertation research project is a standard requirement as a prelude to the process of conducting research and writing a doctoral dissertation for students who complete a doctoral degree in most academic fields including all the branches of the field of education. Many students satisfactorily complete…

A Comparative Analysis of Competency Frameworks for Youth Workers in the Out-of-School Time Field

ERIC Educational Resources Information Center

Vance, Femi

2010-01-01

Research suggests that the quality of out-of-school time (OST) programs is related to positive youth outcomes and skilled staff are a critical component of high quality programming. This descriptive case study of competency frameworks for youth workers in the OST field demonstrates how experts and practitioners characterize a skilled youth worker.…

The Management of Student Affairs Programs in Community Colleges: Revamping Processes and Structures. Horizons Issues Monograph Series.

ERIC Educational Resources Information Center

Deegan, William L.

Based on a review of the management literature in the fields of business and education and on case studies, interviews, and discussions, this monograph identifies the prerequisites for the successful management of student affairs programs. Chapter 1 presents perspectives on the student affairs profession, summarizes the problems facing the field,…

Practical Tips and Tools--Using Stories from the Field for Professional Development: "How-To" Guidelines from Reading to Reflection and Practice Integration

ERIC Educational Resources Information Center

Talmi, Ayelet

2013-01-01

Case studies provide numerous opportunities for professional development and can be particularly helpful in transdiciplinary training. This article offers suggestions for how to use the "Zero to Three" Journal's "Stories From the Field" series of articles across a variety of settings and roles such as clinical practice, program…

A Case Study of Student Teachers' Changing Self-Perceptions in a Field Experience Setting

ERIC Educational Resources Information Center

Cals Southern, Jennifer

2016-01-01

In the field of education new teacher candidates may not be exposed to best practices and given constructive feedback. In fact, student teachers may be at risk of not recognizing their own growing abilities as teachers, which can impact their performance in the classroom. Student teachers' perceptions of their own teaching abilities are greater…

Cross-Field Effects and Temporary Social Fields: A Case Study of the Mediatization of Recent Australian Knowledge Economy Policies

ERIC Educational Resources Information Center

Rawolle, Shaun

2005-01-01

This paper utilizes Bourdieu's conceptual frame to examine the mediatized effects of policy processes concerned with the growth and support of knowledge industries in Australia. These policies span education, science, research and other knowledge industries (such as venture capital firms and intellectual property law). The paper argues that some…

Case Study: Creation of a Degree Program in Computer Security. White Paper.

ERIC Educational Resources Information Center

Belon, Barbara; Wright, Marie

This paper reports on research into the field of computer security, and undergraduate degrees offered in that field. Research described in the paper reveals only one computer security program at the associate's degree level in the entire country. That program, at Texas State Technical College in Waco, is a 71-credit-hour program leading to an…

A Bibliometric Analysis of the Academic Influences of and on Evaluation Theorists' Published Works

ERIC Educational Resources Information Center

Heberger, Anne E.; Christie, Christina A.; Alkin, Marvin C.

2010-01-01

As is the case with other fields, there is motivation for studying the impact that the body of evaluation theory literature has within and outside the field. The authors used journal articles written by theorists included on the evaluation theory tree by Alkin and Christie (2004; Christie & Alkin, 2008) and published in the Web of Science, an…

How much does the time lag between wildlife field-data collection and LiDAR-data acquisition matter for studies of animal distributions? A case study using bird communities

Treesearch

Kerri T. Vierling; Charles E. Swift; Andrew T. Hudak; Jody C. Vogeler; Lee A. Vierling

2014-01-01

Vegetation structure quantified by light detection and ranging (LiDAR) can improve understanding of wildlife occupancy and species-richness patterns. However, there is often a time lag between the collection of LiDAR data and wildlife data. We investigated whether a time lag between the LiDAR acquisition and field-data acquisition affected mapped wildlife distributions...

Strong fields and neutral particle magnetic moment dynamics

NASA Astrophysics Data System (ADS)

Formanek, Martin; Evans, Stefan; Rafelski, Johann; Steinmetz, Andrew; Yang, Cheng-Tao

2018-07-01

Interaction of magnetic moment of point particles with external electromagnetic fields experiences unresolved theoretical and experimental discrepancies. In this work we point out several issues within relativistic quantum mechanics and QED and we describe effects related to a new covariant classical model of magnetic moment dynamics. Using this framework we explore the invariant acceleration experienced by neutral particles coupled to an external plane wave field through the magnetic moment: we study the case of ultrarelativistic Dirac neutrinos with magnetic moment in the range of 10‑11 to 10‑20 μ B; and we address the case of slowly moving neutrons. We explore how critical accelerations for neutrinos can be experimentally achieved in laser pulse interactions. The radiation of accelerated neutrinos can serve as an important test distinguishing between Majorana and Dirac nature of neutrinos.

Coherent manipulation of dipolar coupled spins in an anisotropic environment

NASA Astrophysics Data System (ADS)

Baibekov, E. I.; Gafurov, M. R.; Zverev, D. G.; Kurkin, I. N.; Malkin, B. Z.; Barbara, B.

2014-11-01

We study coherent dynamics in a system of dipolar coupled spin qubits diluted in a solid and subjected to a driving microwave field. In the case of rare earth ions, an anisotropic crystal background results in anisotropic g tensor and thus modifies the dipolar coupling. We develop a microscopic theory of spin relaxation in a transient regime for the frequently encountered case of axially symmetric crystal field. The calculated decoherence rate is nonlinear in the Rabi frequency. We show that the direction of a static magnetic field that corresponds to the highest spin g factor is preferable in order to obtain a higher number of coherent qubit operations. The results of calculations are in excellent agreement with our experimental data on Rabi oscillations recorded for a series of CaW O4 crystals with different concentrations of N d3 + ions.

Propagation of waves from an arbitrary shaped surface-A generalization of the Fresnel diffraction integral

NASA Astrophysics Data System (ADS)

Feshchenko, R. M.; Vinogradov, A. V.; Artyukov, I. A.

2018-04-01

Using the method of Laplace transform the field amplitude in the paraxial approximation is found in the two-dimensional free space using initial values of the amplitude specified on an arbitrary shaped monotonic curve. The obtained amplitude depends on one a priori unknown function, which can be found from a Volterra first kind integral equation. In a special case of field amplitude specified on a concave parabolic curve the exact solution is derived. Both solutions can be used to study the light propagation from arbitrary surfaces including grazing incidence X-ray mirrors. They can find applications in the analysis of coherent imaging problems of X-ray optics, in phase retrieval algorithms as well as in inverse problems in the cases when the initial field amplitude is sought on a curved surface.

Particle acceleration in pulsar magnetospheres

NASA Technical Reports Server (NTRS)

Baker, K. B.

1978-01-01

The structure of pulsar magnetospheres and the acceleration mechanism for charged particles in the magnetosphere was studied using a pulsar model which required large acceleration of the particles near the surface of the star. A theorem was developed which showed that particle acceleration cannot be expected when the angle between the magnetic field lines and the rotation axis is constant (e.g. radial field lines). If this angle is not constant, however, acceleration must occur. The more realistic model of an axisymmetric neutron star with a strong dipole magnetic field aligned with the rotation axis was investigated. In this case, acceleration occurred at large distances from the surface of the star. The magnitude of the current can be determined using the model presented. In the case of nonaxisymmetric systems, the acceleration is expected to occur nearer to the surface of the star.

A Clockwork Wikipedia: From a Broad Perspective to a Case Study.

PubMed

Benjakob, Omer; Aviram, Rona

2018-06-01

While research has shown that scientists use Wikipedia and that scientific content on Wikipedia ramifies back into scientific literature, many questions remain on how the two sides interact and through what paradigm this dynamic may be best understood. Using the circadian clock field as a case study, we discuss this scientific field's representation on Wikipedia. We traced the changes made to the articles for "Circadian clock" and "Circadian rhythm" and reviewed the debates that informed them over a span of a decade, using Wikipedia's native and third-party tools. Specifically, we focused on how groundbreaking research pertaining to the function of biological oscillators was integrated into the articles to reflect a wider paradigmatic shift within the field. We also identified the articles' main editors to detail the dynamic collective editorial process that took place during a time that saw the field undergo a fundamental change. We discuss the different concerns the academic community has with Wikipedia-specifically regarding its content and its contributors-to ask whether the online encyclopedia's open model is inherently at odds with scientific culture or whether the model could reflect science or even expand on its core values and practices such as peer review and the idea of communicating science.

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

PubMed

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

2013-07-01

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

Double Current Sheet Instabilities and the Transition to Turbulence.

NASA Astrophysics Data System (ADS)

Pucci, F.; Velli, M.; Biferale, L.; Sahoo, G.

2016-12-01

The double tearing instability has often been studied as a proxy for the m=1 kink mode in cylindrical plasma. In this paper we describe the results of 3D simulations of an initially periodic double current sheet described by Harris equilibria with a guide field in two cases: 1) zero net helicity and an average magnetic field and 2) a well defined helicity (force free but non constant alpha). We study and contrast the de-stabilization and transition to turbulence for these two cases: we describe spectra, cascades, and possible application to heliospheric phenomena, in particular CME evolution and relaxation. The research leading to these results has received fund- ing from the European Union's Seventh Framework Pro- gramme (FP7/2007-2013) under grant agreement No. 339032

Renormalization of a tensorial field theory on the homogeneous space SU(2)/U(1)

NASA Astrophysics Data System (ADS)

Lahoche, Vincent; Oriti, Daniele

2017-01-01

We study the renormalization of a general field theory on the homogeneous space (SU(2)/ ≤ft. U(1)\\right){{}× d} with tensorial interaction and gauge invariance under the diagonal action of SU(2). We derive the power counting for arbitrary d. For the case d  =  4, we prove perturbative renormalizability to all orders via multi-scale analysis, study both the renormalized and effective perturbation series, and establish the asymptotic freedom of the model. We also outline a general power counting for the homogeneous space {{≤ft(SO(D)/SO(D-1)\\right)}× d} , of direct interest for quantum gravity models in arbitrary dimension, and point out the obstructions to the direct generalization of our results to these cases.

Sensitization of photoconductivity in ferrocene-containing oligomer by squarylium and merocyanine dyes

NASA Astrophysics Data System (ADS)

Davidenko, N. A.; Ishchenko, A. A.; Kozinets, A. V.; Kostenko, L. I.; Kurdyukova, I. V.; Mokrinskaya, E. V.; Studzinskii, S. L.; Chuprina, N. G.

2011-03-01

We have studied the photoconducting properties of films of ferrocene-containing oligomer with additives of squarylium and merocyanine dyes based on ferrocene and tetranitrofluorene in the dye absorption region. We have studied the characteristic features of the effect of an external magnetic field on the photocurrents. After the magnetic field is turned on, the photocurrent increases in the samples with squarylium dye and decreases in the samples with merocyanine dye. We discuss the hypothesis that in the first case, as a result of an internal photoelectric effect, predominantly triplet charge pairs are formed, while in the second case predominantly singlet charge pairs are formed. The latter may be one of the reasons for the higher photoconductivity of films with squarylium dye compared with merocyanine dye.

A comparison of the uniaxial deformation of copper and nickel (1 1 19) surfaces: a molecular dynamics study

PubMed Central

Pukšič, Nuša; Jenko, Monika; Godec, Matjaž; McGuiness, Paul J.

2017-01-01

While a lot is known about the deformation of metallic surfaces from experiments, elasticity theory and simulations, this investigation represents the first molecular-dynamics-based simulation of uniaxial deformation for the vicinal surfaces in a comparison of copper and nickel. These vicinal surfaces are composed of terraces divided by equidistant, mono-atomic steps. The periodicity of vicinals makes them good candidates for the study of the surface steps’ influences on surface dynamics. The simulations of tensile and compressive uniaxial deformations were performed for the (1 1 19) vicinal surfaces. Since the steps on the surfaces serve as stress concentrators, the first defects were expected to nucleate here. In the case of copper, this was found to be the case. In the case of nickel, however, dislocations nucleated beneath the near-surface layer affected by the displacement field generated by the steps. Slip was hindered at the surface step by the vortex in the displacement field. The differences in the deformation mechanisms for the Ni(1 1 19) and Cu(1 1 19) surfaces can be linked to the differences in their displacement fields. This could lead to novel bottom-up approaches to the nanostructuring of surfaces using strain. PMID:28169377

ULF waves in the Martian foreshock: MAVEN observations

NASA Astrophysics Data System (ADS)

Shan, Lican; Mazelle, Christian; Meziane, Karim; Ruhunusiri, Suranga; Espley, Jared; Halekas, Jasper; Connerney, Jack; McFadden, Jim; Mitchell, Dave; Larson, Davin; Brain, Dave; Jakosky, Bruce; Ge, Yasong; Du, Aimin

2016-04-01

Foreshock ULF waves constitute a significant physical phenomenon of the plasma environment for terrestrial planets. The occurrence of these ULF waves, associated with backstreaming ions reflected and accelerated at the bow shock, implies specific conditions and properties of the shock and its foreshock. Using measurements from MAVEN, we report clear observations of this type of ULF waves in the Martian foreshock. We show from different case studies that the peak frequency of the wave case in spacecraft frame is too far from the local ion cyclotron frequency to be associated with local pickup ions taking into account the Doppler shifted frequency from a cyclotron resonance, the obliquity of the mode, resonance broadening and experimental uncertainties. On the opposite their properties fit very well with foreshock waves driven unstable by backtreaming field-aligned ion beams. The propagation angle is usually less than 30 degrees from ambient magnetic field. The waves also display elliptical and left-hand polarizations with respect to interplanetary magnetic field in the spacecraft frame. It is clear for these cases that foreshock ions are simultaneous present for the ULF wave interval. Such observation is important in order to discriminate with the already well-reported pickup ion (protons) waves associated with exospheric hydrogen in order to quantitatively use the later to study seasonal variations of the hydrogen corona.

Explosive Cyclogenesis Over the Eastern United States.

NASA Astrophysics Data System (ADS)

MacDonald, Bruce Calvin

Cases of explosive cyclogenesis occurring over the east central United States are identified and analyzed. Other selected cases of weak or nonintensifying cyclones over the same area are identified and studied for comparative purposes. Signatures of explosively deepening cyclones (bombs) are derived from the analyses, including vertical profiles of vorticity, divergence, and latent heating, and also the relative importance of terms in the vorticity tendency equation and the relative importance of convective and stable latent heating. Composite analyses for the differing phases of bomb development and for regular cyclones are presented. Analyses of individual cases reveal the importance of a low-level jet streak, low-level moisture content, and moisture gradients in the lower troposphere. A numerical model is used to further examine the important processes in explosive cyclogenesis. A mesoscale feature is introduced to improve the prediction of sea -level pressure. This feature is based on the tendency of the large scale height field and vorticity field to adjust concurrently at each time step. The model is also used to provide air parcel trajectories to indicate the importance of parcels with high vorticity and moisture content as an ingredient in explosive cyclogenesis. Sensitivity studies are carried out with the model in order to determine the effect of changes in the initial vorticity and moisture field on cyclogenesis.

A new concept of a hybrid trapped field magnet lens

NASA Astrophysics Data System (ADS)

Takahashi, Keita; Fujishiro, Hiroyuki; Ainslie, Mark D.

2018-04-01

In this paper, a new concept of a hybrid trapped field magnet lens (HTFML) is proposed. The HTMFL exploits the ‘vortex pinning effect’ of an outer superconducting bulk cylinder, which is magnetized as a trapped field magnet (TFM) using field-cooled magnetization (FCM), and the ‘diamagnetic shielding effect’ of an inner bulk magnetic lens to generate a concentrated magnetic field higher than the trapped field from the TFM in the bore of the magnetic lens. This requires that, during the zero-field-cooled magnetization process, the outer cylinder is in the normal state (T> superconducting transition temperature, T c) and the inner lens is in the superconducting state (T < T c) when the external magnetizing field is applied, followed by cooling to an appropriate operating temperature, then removing the external field. This is explored for two potential cases: (1) exploiting the difference in T c of two different bulk materials (‘case-1’), e.g. MgB2 (T c = 39 K) and GdBaCuO (T c = 92 K) or (2) using the same material for the whole HTFML, e.g., GdBaCuO, but utilizing individually controlled cryostats, the same cryostat with different cooling loops or coolants, or heaters that keep the outer bulk cylinder at a temperature above T c to achieve the same desired effect. The HTFML is verified using numerical simulations for ‘case-1’ using an MgB2 cylinder and GdBaCuO lens pair and for ‘case-2’ using a GdBaCuO cylinder and GdBaCuO lens pair. As a result, the HTFML could reliably generate a concentrated magnetic field B c = 4.73 T with the external magnetizing field B app = 3 T in the ‘case-1’, and a higher B c = 13.49 T with higher B app = 10 T in the ‘case-2’, respectively. This could, for example, be used to enhance the magnetic field in the bore of a bulk superconducting NMR/MRI system to improve its resolution.

Merging for Particle-Mesh Complex Particle Kinetic Modeling of the Multiple Plasma Beams

NASA Technical Reports Server (NTRS)

Lipatov, Alexander S.

2011-01-01

We suggest a merging procedure for the Particle-Mesh Complex Particle Kinetic (PMCPK) method in case of inter-penetrating flow (multiple plasma beams). We examine the standard particle-in-cell (PIC) and the PMCPK methods in the case of particle acceleration by shock surfing for a wide range of the control numerical parameters. The plasma dynamics is described by a hybrid (particle-ion-fluid-electron) model. Note that one may need a mesh if modeling with the computation of an electromagnetic field. Our calculations use specified, time-independent electromagnetic fields for the shock, rather than self-consistently generated fields. While a particle-mesh method is a well-verified approach, the CPK method seems to be a good approach for multiscale modeling that includes multiple regions with various particle/fluid plasma behavior. However, the CPK method is still in need of a verification for studying the basic plasma phenomena: particle heating and acceleration by collisionless shocks, magnetic field reconnection, beam dynamics, etc.

Universal horizons and Hawking radiation in nonprojectable 2d Hořava gravity coupled to a nonrelativistic scalar field

NASA Astrophysics Data System (ADS)

Li, Bao-Fei; Bhattacharjee, Madhurima; Wang, Anzhong

2017-10-01

In this paper, we study the nonprojectable 2d Hořava gravity coupled with a nonrelativistic scalar field, where the coupling is, in general, nonminimal and of the form f (ϕ )R , where f (ϕ ) is an arbitrary function of the scalar field ϕ , and R denotes the 2d Ricci scalar. In particular, we first investigate the Hamiltonian structure and show that there are two first- and two second-class constraints, similar to the pure gravity case, but now the local degrees of freedom is one due to the presence of the scalar field. Then, we present various exact stationary solutions of this coupled system, and find that some of them represent black holes, but now with universal horizons as their boundaries. At these horizons, the Hawking radiation is thermal with temperatures proportional to their surface gravities, which normally depend on the nonlinear dispersion relations of the particles radiated, similar to the (3 +1 )-dimensional case.

Three dimensional magnetohydrodynamic simulation of linearly polarised Alfven wave dynamics in Arnold-Beltrami-Childress magnetic field

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

Tsiklauri, D.

Previous studies (e.g., Malara et al., Astrophys. J. 533, 523 (2000)) considered small-amplitude Alfven wave (AW) packets in Arnold-Beltrami-Childress (ABC) magnetic field using WKB approximation. They draw a distinction between 2D AW dissipation via phase mixing and 3D AW dissipation via exponentially divergent magnetic field lines. In the former case, AW dissipation time scales as S{sup 1∕3} and in the latter as log(S), where S is the Lundquist number. In this work, linearly polarised Alfven wave dynamics in ABC magnetic field via direct 3D magnetohydrodynamic (MHD) numerical simulation is studied for the first time. A Gaussian AW pulse with length-scalemore » much shorter than ABC domain length and a harmonic AW with wavelength equal to ABC domain length are studied for four different resistivities. While it is found that AWs dissipate quickly in the ABC field, contrary to an expectation, it is found the AW perturbation energy increases in time. In the case of the harmonic AW, the perturbation energy growth is transient in time, attaining peaks in both velocity and magnetic perturbation energies within timescales much smaller than the resistive time. In the case of the Gaussian AW pulse, the velocity perturbation energy growth is still transient in time, attaining a peak within few resistive times, while magnetic perturbation energy continues to grow. It is also shown that the total magnetic energy decreases in time and this is governed by the resistive evolution of the background ABC magnetic field rather than AW damping. On contrary, when the background magnetic field is uniform, the total magnetic energy decrease is prescribed by AW damping, because there is no resistive evolution of the background. By considering runs with different amplitudes and by analysing the perturbation spectra, possible dynamo action by AW perturbation-induced peristaltic flow and inverse cascade of magnetic energy have been excluded. Therefore, the perturbation energy growth is attributed to a new instability. The growth rate appears to be dependent on the value of the resistivity and the spatial scale of the AW disturbance. Thus, when going beyond WKB approximation, AW damping, described by full MHD equations, does not guarantee decrease of perturbation energy. This has implications for the MHD wave plasma heating in exponentially divergent magnetic fields.« less

Direct comparison between satellite electric field measurements and the visual aurora

NASA Technical Reports Server (NTRS)

Swift, D. W.; Gurnett, D. A.

1973-01-01

Electric field data from two passes of the Injun 5 satellite, one corresponding to magnetically quiet conditions and one corresponding to substorm conditions, are compared with simultaneous all-sky-camera data from College, Alaska. In each case, a significant deviation of the electric field from the expected V x B field (where V is the satellite velocity) was evident and a distinct electric field reversal could be identified. In the region of substantial electric field equatorward of the electric field reversal a diffuse auroral arc was observed during the magnetically quiet pass and auroral patches were observed during the substorm pass. The motion of the auroral patches was consistent with the general direction and magnitude of the E x B drift computed from the satellite electric field measurements. In the substorm case the electric field reversal occurred very near a discrete auroral arc at the poleward side of the diffuse arcs and patches. Comparison of the quiet time and substorm cases suggests that the convection electric field penetrates deeper into the magnetosphere during a substorm.

A preliminary characterization of applied-field MPD thruster plumes

NASA Technical Reports Server (NTRS)

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

1991-01-01

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

Acceleration of metal-atom diffusion in electric field at metal/insulator interfaces: First-principles study

NASA Astrophysics Data System (ADS)

Nagasawa, Riki; Asayama, Yoshihiro; Nakayama, Takashi

2018-04-01

Metal-atom diffusion from metal electrodes into SiO2 in electric fields was studied using first-principles calculations. It was shown in the case without electric field that the diffusion barrier of a metal atom is mainly made of the cohesive energy of bulk metal layers, while the shape of the diffusion potential reflects the hybridization of the metal-atom state with metal-induced gap states (MIGSs) and the electron transfer between the metal atom and the electrode. We found that the metal-atom diffusion is markedly accelerated by the applied electric field, such that the diffusion barrier ϕB(E) decreases almost linearly with increasing electric field strength E. By analyzing the physical origins of the metal-atom diffusion, we derived the universal formula to estimate the diffusion barrier in the electric field, which is closely related to MIGSs.

Invariant models in the inversion of gravity and magnetic fields and their derivatives

NASA Astrophysics Data System (ADS)

Ialongo, Simone; Fedi, Maurizio; Florio, Giovanni

2014-11-01

In potential field inversion problems we usually solve underdetermined systems and realistic solutions may be obtained by introducing a depth-weighting function in the objective function. The choice of the exponent of such power-law is crucial. It was suggested to determine it from the field-decay due to a single source-block; alternatively it has been defined as the structural index of the investigated source distribution. In both cases, when k-order derivatives of the potential field are considered, the depth-weighting exponent has to be increased by k with respect that of the potential field itself, in order to obtain consistent source model distributions. We show instead that invariant and realistic source-distribution models are obtained using the same depth-weighting exponent for the magnetic field and for its k-order derivatives. A similar behavior also occurs in the gravity case. In practice we found that the depth weighting-exponent is invariant for a given source-model and equal to that of the corresponding magnetic field, in the magnetic case, and of the 1st derivative of the gravity field, in the gravity case. In the case of the regularized inverse problem, with depth-weighting and general constraints, the mathematical demonstration of such invariance is difficult, because of its non-linearity, and of its variable form, due to the different constraints used. However, tests performed on a variety of synthetic cases seem to confirm the invariance of the depth-weighting exponent. A final consideration regards the role of the regularization parameter; we show that the regularization can severely affect the depth to the source because the estimated depth tends to increase proportionally with the size of the regularization parameter. Hence, some care is needed in handling the combined effect of the regularization parameter and depth weighting.

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

Zúñiga-Segundo, Arturo; Juárez-Amaro, Raúl; Aguilar-Loreto, Omar

We study the atom–field interaction when the field is in a mixture of coherent states. We show that in this case it is possible to calculate analytically the field entropy for times of the order of twice the collapse time. Such analytical results are done with the help of numerical analysis. We also give an expression in terms of Chebyshev polynomials for power of density matrices. - Highlights: • We calculate the field entropy for times of the order of twice the collapse time. • We give a relation between powers of the density matrices of the subsystems. • Entropymore » operators for both subsystems are obtained.« less

The effect of external magnetic field changing on the correlated quantum dot dynamics

NASA Astrophysics Data System (ADS)

Mantsevich, V. N.; Maslova, N. S.; Arseyev, P. I.

2018-06-01

The non-stationary response of local magnetic moment to abrupt switching "on" and "off" of external magnetic field was studied for a single-level quantum dot (QD) coupled to a reservoir. We found that transient processes look different for the shallow and deep localized energy level. It was demonstrated that for deep energy level the relaxation rates of the local magnetic moment strongly differ in the case of magnetic field switching "on" or "off". Obtained results can be applied in the area of dynamic memory devices stabilization in the presence of magnetic field.

Aerospace devices for magnetic replicas

NASA Technical Reports Server (NTRS)

Weinstein, Roy

1993-01-01

Retained persistent magnetic field has been studied and improved in the superconductor YBa2Cu3O7 (Y123). During the study, trapped magnetic field, B(t), has been increased by over a factor of 10(exp 5). Methods used to improve magnetic field trapping were principally: (1) the adoption of the Melt Texturing process to increase grain size; (2) the addition of excess Y to disperse deposits of Y2BaCuO5 (Y211) and again increase grain size; (3) irradiation with high energy particles including 1H+, 3He++, 4He++, and fission fragments; and (4) utilizing temperatures below 77 K has also been quantified as a way to increase trapped field. In addition, in our study of B(t), we have found laws governing creep, activation, temperature dependence, creep vs. current flow, etc. In the range 20 K less than or equal to T less than or equal to 65 K, and for B less than 10 Tesla, a simple empirical relationship was found: B(trap) (T2) = B(trap) (T1) ((Tc - T2)/(Tc - T1))squared where Tc is the critical temperature. The highest experimental trapped field was B(trap) = 3.96 Tesla, at 65 K. We believe this to be the highest persistent field ever produced, by any method. A two component model of the persistent currents has been developed. This accurately reproduces the data, using as parameters only the magnitude of a constant surface current, J(s), and a constant volume current J(v). The model successfully predicts B(t) (xyz) for the case of maximum trapped field, for all samples observed. It has also been extended to describe the unsaturated case either zero field cooled, or field cooled. Loss of strap with time has been studied for the critical state (Bt,max), and non critical state (Bt less than Bt,max), for times from a few minutes to a few months, for unirradiated material, for irradiation by 1H+, 3He++, 4He++, high z projectiles, and neutrons, and for all materials used in the overall study. We conclude that: (1) multi Tesla trapped fields are attained; (2) fields over 10 T are achievable; (3) creep is not a large problem; (4) application is feasible to motors, generators, magnets for particle beam optics, separators, levitating bearings, energy storage, shielding, and transportation.

Grain-grain interaction in stationary dusty plasma

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

Lampe, Martin; Joyce, Glenn

We present a particle-in-cell simulation study of the steady-state interaction between two stationary dust grains in uniform stationary plasma. Both the electrostatic force and the shadowing force on the grains are calculated explicitly. The electrostatic force is always repulsive. For two grains of the same size, the electrostatic force is very nearly equal to the shielded electric field due to a single isolated grain, acting on the charge of the other grain. For two grains of unequal size, the electrostatic force on the smaller grain is smaller than the isolated-grain field, and the force on the larger grain is largermore » than the isolated-grain field. In all cases, the attractive shadowing force exceeds the repulsive electrostatic force when the grain separation d is greater than an equilibrium separation d{sub 0}. d{sub 0} is found to be between 6λ{sub D} and 9λ{sub D} in all cases. The binding energy is estimated to be between 19 eV and 900 eV for various cases.« less

Non-stationary measurements of Chiral Magnetic Effect

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

Shevchenko, V.I., E-mail: vladimir.i.shevchenko@gmail.com

2013-12-15

We discuss the Chiral Magnetic Effect from the quantum theory of measurements point of view for non-stationary measurements. The effect of anisotropy for fluctuations of electric currents in a magnetic field is addressed. It is shown that anisotropy caused by nonzero axial chemical potential is indistinguishable in this framework from anisotropy caused by finite measurement time or finite lifetime of the magnetic field, and in all cases it is related to abelian triangle anomaly. Possible P-odd effects in central heavy-ion collisions (where the Chiral Magnetic Effect is absent) are discussed in this context. This paper is dedicated to the memorymore » of Professor Mikhail Polikarpov (1952–2013). -- Highlights: •Asymmetry in the response function for vector currents of massless fermions in the magnetic field is computed. •Asymmetry caused by axial chemical potential is practically indistinguishable from the one caused by non-stationarity. •The CME current is non-dissipative in the stationary case and dissipative in the non-stationary case. •Importance of studies of P-odd signatures in central collisions is emphasized.« less

Influence of a constant and variable magnetic field on the coagulation of human blood in vitro and in vivo

NASA Technical Reports Server (NTRS)

Degen, I. L.; Plaksenko, V. Y.

1974-01-01

The influence of constant and varying magnetic fields on the coagulation of the blood was studied in experiments performed in vitro and vivo. In the in vitro tests it was found that a constant magnetic field with a strength of 100 or 200 oersteds influences the coagulation of the blood, retarding it in some cases and speeding up the coagulation time in others. In the in vivo studies, both retarding and accelerating effects were likewise observed with respect to the coagulation of the blood, but the nature of the change was a function of the background. A normalizing effect of the magnetic field on the coagulation of the blood was observed.

Deconfinement phase transition in a magnetic field in 2 + 1 dimensions from holographic models

NASA Astrophysics Data System (ADS)

M. Rodrigues, Diego; Capossoli, Eduardo Folco; Boschi-Filho, Henrique

2018-05-01

Using two different models from holographic quantum chromodynamics (QCD) we study the deconfinement phase transition in 2 + 1 dimensions in the presence of a magnetic field. Working in 2 + 1 dimensions lead us to exact solutions on the magnetic field, in contrast with the case of 3 + 1 dimensions where the solutions on the magnetic field are perturbative. As our main result we predict a critical magnetic field Bc where the deconfinement critical temperature vanishes. For weak fields meaning B Bc we find that the critical temperature raises with growing field showing a magnetic catalysis (MC). These results for IMC and MC are in agreement with the literature.

Magnetic field experiment for Voyagers 1 and 2

NASA Technical Reports Server (NTRS)

Behannon, K. W.; Aluna, M. H.; Burlaga, L. F.; Lepping, R. P.; Ness, N. F.; Neubauer, F. M.

1977-01-01

The magnetic field experiment to be carried on the Voyager 1 and 2 missions consists of dual low field (LFM) and high field magnetometer (HFM) systems. The dual systems provide greater reliability and, in the case of the LFM's, permit the separation of spacecraft magnetic fields from the ambient fields. Additional reliability is achieved through electronics redundancy. The wide dynamic ranges of plus or minus 0.5G for the LFM's and plus or minus 20G for the HFM's, low quantization uncertainty of plus or minus 0.002 gamma in the most sensitive (plus or minus 8 gamma) LFM range, low sensor RMS noise level of 0.006 gamma, and use of data compaction schemes to optimize the experiment information rate all combine to permit the study of a broad spectrum of phenomena during the mission. Planetary fields at Jupiter, Saturn, and possibly Uranus; satellites of these planets; solar wind and satellite interactions with the planetary fields; and the large-scale structure and microscale characteristics of the interplanetary magnetic field are studied. The interstellar field may also be measured.

Childhood cancer and magnetic fields from high-voltage power lines in England and Wales: a case–control study

PubMed Central

Kroll, M E; Swanson, J; Vincent, T J; Draper, G J

2010-01-01

Background: Epidemiological evidence suggests that chronic low-intensity extremely-low-frequency magnetic-field exposure is associated with increased risk of childhood leukaemia; it is not certain the association is causal. Methods: We report a national case–control study relating childhood cancer risk to the average magnetic field from high-voltage overhead power lines at the child's home address at birth during the year of birth, estimated using National Grid records. From the National Registry of Childhood Tumours, we obtained records of 28 968 children born in England and Wales during 1962–1995 and diagnosed in Britain under age 15. We selected controls from birth registers, matching individually by sex, period of birth, and birth registration district. No participation by cases or controls was required. Results: The estimated relative risk for each 0.2 μT increase in magnetic field was 1.14 (95% confidence interval 0.57 to 2.32) for leukaemia, 0.80 (0.43–1.51) for CNS/brain tumours, and 1.34 (0.84–2.15) for other cancers. Conclusion: Although not statistically significant, the estimate for childhood leukaemia resembles results of comparable studies. Assuming causality, the estimated attributable risk is below one case per year. Magnetic-field exposure during the year of birth is unlikely to be the whole cause of the association with distance from overhead power lines that we previously reported. PMID:20877338

Image-Based High-Throughput Field Phenotyping of Crop Roots1[W][OPEN

PubMed Central

Bucksch, Alexander; Burridge, James; York, Larry M.; Das, Abhiram; Nord, Eric; Weitz, Joshua S.; Lynch, Jonathan P.

2014-01-01

Current plant phenotyping technologies to characterize agriculturally relevant traits have been primarily developed for use in laboratory and/or greenhouse conditions. In the case of root architectural traits, this limits phenotyping efforts, largely, to young plants grown in specialized containers and growth media. Hence, novel approaches are required to characterize mature root systems of older plants grown under actual soil conditions in the field. Imaging methods able to address the challenges associated with characterizing mature root systems are rare due, in part, to the greater complexity of mature root systems, including the larger size, overlap, and diversity of root components. Our imaging solution combines a field-imaging protocol and algorithmic approach to analyze mature root systems grown in the field. Via two case studies, we demonstrate how image analysis can be utilized to estimate localized root traits that reliably capture heritable architectural diversity as well as environmentally induced architectural variation of both monocot and dicot plants. In the first study, we show that our algorithms and traits (including 13 novel traits inaccessible to manual estimation) can differentiate nine maize (Zea mays) genotypes 8 weeks after planting. The second study focuses on a diversity panel of 188 cowpea (Vigna unguiculata) genotypes to identify which traits are sufficient to differentiate genotypes even when comparing plants whose harvesting date differs up to 14 d. Overall, we find that automatically derived traits can increase both the speed and reproducibility of the trait estimation pipeline under field conditions. PMID:25187526

A Multi-Year Program Developing an Explicit Reflective Pedagogy for Teaching Pre-service Teachers the Nature of Science by Ostention

NASA Astrophysics Data System (ADS)

Smith, Mike U.; Scharmann, Lawrence

2008-02-01

This investigation delineates a multi-year action research agenda designed to develop an instructional model for teaching the nature of science (NOS) to preservice science teachers. Our past research strongly supports the use of explicit reflective instructional methods, which includes Thomas Kuhn’s notion of learning by ostention and treating science as a continuum (i.e., comparing fields of study to one another for relative placement as less to more scientific). Instruction based on conceptual change precepts, however, also exhibits promise. Thus, the investigators sought to ascertain the degree to which conceptual change took place among students (n = 15) participating in the NOS instructional model. Three case studies are presented to illustrate successful conceptual changes that took place as a result of the NOS instructional model. All three cases represent students who claim a very conservative Christian heritage and for whom evolution was not considered a legitimate scientific theory prior to participating in the NOS instructional model. All three case study individuals, along with their twelve classmates, placed evolution as most scientific when compared to intelligent design and a fictional field of study called “Umbrellaology.”

A nonlinear theory for spinning anisotropic beams using restrained warping functions

NASA Technical Reports Server (NTRS)

Ie, C. A.; Kosmatka, J. B.

1993-01-01

A geometrically nonlinear theory is developed for spinning anisotropic beams having arbitrary cross sections. An assumed displacement field is developed using the standard 3D kinematics relations to describe the global beam behavior supplemented with an additional field that represents the local deformation within the cross section and warping out of the cross section plane. It is assumed that the magnitude of this additional field is directly proportional to the local stress resultants. In order to take into account the effects of boundary conditions, a restraining function is introduced. This function plays the role of reducing the amount of free warping deformation throughout the field due to the restraint of the cross section(s) at the end(s) of the beam, e.g., in the case of a cantilever beam. Using a developed ordering scheme, the nonlinear strains are calculated to the third order. The FEM is developed using the weak form variational formulation. Preliminary interesting numerical results have been obtained that indicate the role of the restraining function in the case of a cantilever beam with circular cross section. These results are for the cases of a tip displacement (static) and free vibration studies for both isotropic and anisotropic materials with varied fiber orientations.