5,715 research outputs found
Radiation induced zero-resistance states: a dressed electronic structure effect
Recent results on magnetoresistance in a two dimensional electron gas under
crossed magnetic and microwave fields show a new class of oscillations,
suggesting a new kind of zero-resistance states. A complete understanding of
the effect is still lacking. We consider the problem from the point of view of
the electronic structure dressed by photons due to a in plane linearly
polarized ac field. The dramatic changes in the dressed electronic structure
lead to a interpretation of the new magnetoresistance oscillations as a
persistent-current like effect, induced by the radiation field.Comment: 5 pages, 5 figures, revtex4, changes in introduction and added
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A guide to the establishment and maintenance of pesticide laboratories in developing countries (NRI Bulletin No. 28)
The difficulties in establishing and maintaining pesticide laboratories, particularly residue laboratories, in developing countries are addressed in an attempt to arouse a greater awareness of the commitment and resources required for successful operation. Accommodation, staffing, laboratory services, equipment and materials are all considered in detail and model specifications, including full equipment lists, are provided for both formulation and residue laboratories
The Healthy Migrant Families Initiative: Development of a culturally competent obesity prevention intervention for African migrants Disease epidemiology - Chronic
Background: Although obesity among immigrants remains an important area of study given the increasing migrant population in Australia and other developed countries, research on factors amenable to intervention is sparse. The aim of the study was to develop a culturally-competent obesity prevention program for sub-Saharan African (SSA) families with children aged 12-17 years using a community-partnered participatory approach. Methods: A community-partnered participatory approach that allowed the intervention to be developed in collaborative partnership with communities was used. Three pilot studies were carried out in 2008 and 2009 which included focus groups, interviews, and workshops with SSA parents, teenagers and health professionals, and emerging themes were used to inform the intervention content. A cultural competence framework containing 10 strategies was developed to inform the development of the program. Using findings from our scoping research, together with community consultations through the African Review Panel, a draft program outline (skeleton) was developed and presented in two separate community forums with SSA community members and health professionals working with SSA communities in Melbourne. Results: The \u27Healthy Migrant Families Initiative (HMFI): Challenges and Choices\u27 program was developed and designed to assist African families in their transition to life in a new country. The program consists of nine sessions, each approximately 1 1/2 hours in length, which are divided into two modules based on the topic. The first module \u27Healthy lifestyles in a new culture\u27 (5 sessions) focuses on healthy eating, active living and healthy body weight. The second module \u27Healthy families in a new culture\u27 (4 sessions) focuses on parenting, communication and problem solving. The sessions are designed for a group setting (6-12 people per group), as many of the program activities are discussion-based, supported by session materials and program resources. Conclusion: Strong partnerships and participation by SSA migrant communities enabled the design of a culturally competent and evidence-based intervention that addresses obesity prevention through a focus on healthy lifestyles and healthy families. Program implementation and evaluation will further inform obesity prevention interventions for ethnic minorities and disadvantaged communities
On the use of low-cost computer peripherals for the assessment of motor dysfunction in Parkinsonâs disease â Quantification of bradykinesia using target tracking tasks
The potential of computer games peripherals to measure the motor dysfunction in Parkinsonâs diseases is assessed. Of particular interest is the quantification of bradykinesia. Previous studies used modified or custom haptic interfaces, here an unmodified force feedback joystick and steering wheel are used with a laptop. During testing an on screen cursor moves in response to movements of the peripheral, the user has to track a continuously moving target (pursuit tracking), or move to a predetermined target (step tracking). All tasks use movement in the horizontal axis, allowing use of joystick or steering wheel. Two pursuit tracking tasks are evaluated, pseudo random movement, and a swept frequency task. Two step tracking tasks are evaluated, movement between two or between two of five fixed targets. Thirteen patients and five controls took part on a weekly basis. Patients were assessed for bradykinesia at each session using standard clinical measures. A range of quantitative measures was developed to allow comparison between and within patients and controls using ANOVA. Both peripherals are capable of discriminating between controls and patients, and between patients with different levels of bradykinesia. Recommendations for test procedures and peripherals are given
Biot-Savart-like law in electrostatics
The Biot-Savart law is a well-known and powerful theoretical tool used to
calculate magnetic fields due to currents in magnetostatics. We extend the
range of applicability and the formal structure of the Biot-Savart law to
electrostatics by deriving a Biot-Savart-like law suitable for calculating
electric fields. We show that, under certain circumstances, the traditional
Dirichlet problem can be mapped onto a much simpler Biot-Savart-like problem.
We find an integral expression for the electric field due to an arbitrarily
shaped, planar region kept at a fixed electric potential, in an otherwise
grounded plane. As a by-product we present a very simple formula to compute the
field produced in the plane defined by such a region. We illustrate the
usefulness of our approach by calculating the electric field produced by planar
regions of a few nontrivial shapes.Comment: 14 pages, 6 figures, RevTex, accepted for publication in the European
Journal of Physic
Online leadership discourse in higher education: a digital multimodal discourse perspective
As leadership discourses in higher education are increasingly being mediated online, texts previously reserved for staff are now being made available in the public domain. As such, these texts become accessible for study, critique and evaluation. Additionally, discourses previously confined to the written domain are now increasingly multimodal. Thus, an approach is required that is capable of relating detailed, complex multimodal discourse analyses to broader sociocultural perspectives to account for the complex meaning-making practices that operate in online leadership discourses. For this purpose, a digital multimodal discourse approach is proposed and illustrated via a small-scale case study of the online leadership discourse of an Australian university. The analysis of two short video texts demonstrates how a digital multimodal discourse perspective facilitates the identification of key multimodal systems used for meaning-making in online communication, how meaning arises through combinations of semiotic choices (not individual choices), and how the results of multimodal discourse analysis using digital technology can reveal larger sociocultural patterns â in this case, divergent leadership styles and approaches as reflected in online discourse, at a time of immense change within the higher education sector
Sustaining Educational Reforms in Introductory Physics
While it is well known which curricular practices can improve student
performance on measures of conceptual understanding, the sustaining of these
practices and the role of faculty members in implementing these practices are
less well understood. We present a study of the hand-off of Tutorials in
Introductory Physics from initial adopters to other instructors at the
University of Colorado, including traditional faculty not involved in physics
education research. The study examines the impact of implementation of
Tutorials on student conceptual learning across eight first-semester, and seven
second-semester courses, for fifteen faculty over twelve semesters, and
includes roughly 4000 students. It is possible to demonstrate consistently
high, and statistically indistinguishable, student learning gains for different
faculty members; however, such results are not the norm, and appear to rely on
a variety of factors. Student performance varies by faculty background -
faculty involved in, or informed by physics education research, consistently
post higher student learning gains than less-informed faculty. Student
performance in these courses also varies by curricula used - all semesters in
which the research-based Tutorials and Learning Assistants are used have higher
student learning gains than those semesters that rely on non-research based
materials and do not employ Learning Assistants.Comment: 21 pages, 4 figures, and other essential inf
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