3,941 research outputs found
Transport characteristics of L-point and Đ-point electrons through GaAs-Ga_(1-x)Ai_xAs-GaAs(111} double heterojunctions
We present here a study on the transport characteristics of Lâpoint and Îâpoint derived electrons through abrupt GaAsâGa_(1âx)Al_xAsâGaAs(111) double heterojunctions. The use of complexâk band structures in the tightâbinding approximation and transfer matrices provide a reasonably accurate description of the wave function at the GaAsâGa_(1âx)Al_xAs interface. A representation of the wave function in terms of bulk complexâk Bloch states is used in the GaAs regions where the potential is bulklike. A representation of the wave function in terms of planar orbitals is used in the central Ga_(1âx)Al_xAs region where the potential deviates from its bulk value (i.e., interfacial region). Within this theoretical framework, realistic band structure effects are taken into account and no artificial rules regarding the connection of the wave function across the interface are introduced. The tenâband tightâbinding model includes admixture in the total wave function of states derived from different extrema of the GaAs conduction band. States derived from the same extremum of the conduction band appear to couple strongly to each other, whereas states derived from different extrema are found to couple weakly. Transport characteristics of incoming Lâpoint and Îâpoint Bloch states are examined as a function of the energy of the incoming state, thickness of the Ga_(1âx)Al_xAs barrier, and alloy composition x. Transmission through the Ga_(1âx)Al_xAs barrier is either tunneling or propagating depending on the nature of the Bloch states available for strong coupling in the alloy. Since Bloch states derived from different extrema of the conduction band appear to couple weakly to each other, it seems possible to reflect the low velocity Lâpoint component of the current while transmitting the high velocity Îâpoint component
Surface core excitons in III-V semiconductors
Recent experiments have shown that the cation core excitons
on the (110) surface of many III-V semiconductors have very
large binding energies.(^1) They are sometimes reported to be bound by as much as âł0.8 eV, tightly bound compared to
bulk binding energies of âŸ0.1 eV. To explore this phenomenon, we have calculated the binding energies and oscillator strengths of core excitons on the (110) surface of GaAs, GaSb, GaP, and InP
The Dip: Orchestrating a Clinical Immersion Experience in Interprofessional Education
Research Question:
Do health professions students who participate in an interprofessional education experience report improved teamwork skills
Enhancing design learning using a digital repository
The process of design is context dependent and open-ended, and therefore does not revolve around a specific body of information or knowledge. The educational paradigm shift in the area of engineering design from teaching to coaching and the increased use of social constructivist learning ideals requires students to have access to as wide a range of information as possible. Digital resources provide an excellent opportunity for extending the range of information available to design students and to this end, as part of a joint research program with Stanford University, the University of Strathclyde has developed a groupware product called LauLima to provide students with a collaborative environment which allows them to gather, organise, store and share information. This paper describes the improvement to design learning, based on a Design Knowledge Framework, in a 3rd year product design engineering project from session 03/04 to 04/05 which has been facilitated by the implementation of this technology
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Journeys to Open Educational Practice: UKOER/SCORE Review Final Report
In 2008 the JISC Good Intentions report concluded that the landscape around learning materials had changed sufficiently to support a range of sustainable models for sharing. The report charted and acknowledged the long history of approaches to support sharing that had helped to shape the landscape.
Most of the models highlight a growing acknowledgement of the need to build and support open and sustainable communities to share practice and resources. Indeed such communities are often the key to sustaining the service, whichever model is adopted. This is the type of model most likely to encourage sharing between teachers as well as learners.
The growing OER community is taking collaborative approaches to tackling the ongoing challenges of raising awareness, licensing and trust issues, and standards and technologies. The challenge for the UK now is to ensure that our HE institutions are enabled to create policies, practices and support their staff to accelerate the transformations required to contribute and benefit from this global movement. It is also vital to ensure that we capture the real picture of use and re-use of such services and collections to inform future OER programmes.
HEFCE funding for OER initiatives followed this report in 2009 and has, in many ways, provided some of the scaffolding and support for a variety of individuals, communities and institutions to move forwards in their own journeys, whether they started years before in other contexts or had just joined on the road to open sharing
Navigating the Hazardous Terrain and the Tranquil Waters: A Grounded Theory Study of the Leadership Development of Nurse Managers
The purpose of this grounded theory study was to provide nurse managers in two healthcare organizations with an opportunity to share their reflections on their leadership development and transition from staff nurse to nurse manager. This qualitative study provides analysis grounded in the data and themes from the interviews, developing theory, and recommendations, which should prove useful to the leaders in the agencies where the study was done.
Through 19 semi-structured interviews of current or previous nurse managers, the participants described what contributed to their leadership development and the challenges they encountered. In the category of contributors, the themes included identity and purpose, âEmotional Intelligenceâ, mental models of continuous learning, and a nurturing community. Challenges included the transition from staff to manager, learning from adversity, and the large scope and rapid pace of change.
The researcher conducted an analysis of the findings using the lenses of Symbolic Interactionism (SI) combined with Goffmanâs (1959) dramaturgy and theatrical performance, and the four frames of Bolman and Deal (2008). There are definite front stage and back stage aspects to the leadership development of nurse managers. These theories help represent the complexity of the individual and organizational aspects of the leadership development of nurse managers. Additionally, a theory emerged that outlined the symbiotic forces which help nurses develop as leaders. These symbiotic forces include the hazardous terrain with the unpredictable and the unknown, as well as the tranquil waters of reflection, renewal, and support. The theory also describes the ripple effect of nurse managers as leaders in the organizational context. The study yielded significant implications and recommendations for nursing educators, nursing practice and the organization, nurse leaders, and future researchers
Microscopic processes during electron cyclotron resonance microwave nitrogen plasma-assisted molecular beam epitaxial growth of GaN/GaAs heterostructures: Experiments and kinetic modeling
A set of delta-GaNyAs1ây/GaAs strained-layer superlattices grown on GaAs (001) substrates by electron cyclotron resonance (ECR) microwave plasma-assisted molecular beam epitaxy (MBE) was characterized by ex situ high resolution X-ray diffraction (HRXRD) to determine nitrogen content y in the nitrided GaAs monolayers as a function of growth temperature T. A first order kinetic model is introduced to quantitatively explain this y(T) dependence in terms of an energetically favorable N for As anion exchange and thermally activated N-surface desorption and surface segregation processes. The nitrogen surface segregation process, with an estimated activation energy Es ~ 0.9 eV appears to be significant during the GaAs overgrowth of GaNyAs1ây layers, and is shown to be responsible for strong y(T) dependence
Comparing and calibrating black hole mass estimators for distant active galactic nuclei
Black hole mass is a fundamental property of active galactic nuclei (AGNs).
In the distant universe, black hole mass is commonly estimated using the MgII,
Hbeta, or Halpha emission line widths and the optical/UV continuum or line
luminosities, as proxies for the characteristic velocity and size of the
broad-line region. Although they all have a common calibration in the local
universe, a number of different recipes are currently used in the literature.
It is important to verify the relative accuracy and consistency of the recipes,
as systematic changes could mimic evolutionary trends when comparing various
samples. At z=0.36, all three lines can be observed at optical wavelengths,
providing a unique opportunity to compare different empirical recipes. We use
spectra from the Keck Telescope and the Sloan Digital Sky Survey to compare
black hole mass estimators for a sample of nineteen AGNs at this redshift. We
compare popular recipes available from the literature, finding that mass
estimates can differ up to 0.38+-0.05 dex in the mean (or 0.13+-0.05 dex, if
the same virial coefficient is adopted). Finally, we provide a set of 30
internally self consistent recipes for determining black hole mass from a
variety of observables. The intrinsic scatter between cross-calibrated recipes
is in the range 0.1-0.3 dex. This should be considered as a lower limit to the
uncertainty of the black hole mass estimators.Comment: ApJ in press, 11 pages, 10 figure
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