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Engagement and Positive Psychology for STEM Learning and Beyond
Positive psychology is the study of how people flourish. A considerable amount of recent scientific research is now showing how the basic tenets of positive psychology used in schools can boost engagement, learning and wellbeing for students and teachers. These principles apply to any type of learning, including STEM courses. The concepts and practices of positive psychology effectively serve as affective multipliers, enhancing learning success and personal wellbeing. This seminar will introduce a sampler plate of ideas and activities from their course for first-year UMass students, entitled “Positive Psychology: The Science of Happiness, Creativity, and Accomplishment.
National Nanomanufacturing Network Events 2011
Nanoinformatics 2011 brought together informatics experts, nanotechnology researchers, and other stakeholders and potential contributors to advance Nanoinformatics 2020 Roadmap goals. The workshop will set a clear path for Nanoinformatics participants through the presentation of projects and research, open discussions, and strategic planning sessions. The Nanomanufacturing Summit 2011 – showcased emerging areas of nanomanufacturing and commercialization of nanotechnology-enabled products by leaders in the field of nanomanufacturing
Polarization Dependent Switching of Asymmetric Nanorings with a Circular Field
We experimentally investigated the switching from onion to vortex states in asymmetric cobalt nanorings by an applied circular field. An in-plane field is applied along the symmetric or asymmetric axis of the ring to establish domain walls (DWs) with symmetric or asymmetric polarization. A circular field is then applied to switch from the onion state to the vortex state, moving the DWs in the process. The asymmetry of the ring leads to different switching fields depending on the location of the DWs and direction of applied field. For polarization along the asymmetric axis, the field required to move the DWs to the narrow side of the ring is smaller than the field required to move the DWs to the larger side of the ring. For polarization along the symmetric axis, establishing one DW in the narrow side and one on the wide side, the field required to switch to the vortex state is an intermediate value
Incoherent dynamics of vibrating single-molecule transistors
We study the tunneling conductance of nano-scale quantum ``shuttles'' in
connection with a recent experiment (H. Park et al., Nature, 407, 57 (2000)) in
which a vibrating C^60 molecule was apparently functioning as the island of a
single electron transistor (SET). While our calculation starts from the same
model of previous work (D. Boese and H. Schoeller, Europhys. Lett. 54,
66(2001)) we obtain quantitatively different dynamics. Calculated I-V curves
exhibit most features present in experimental data with a physically reasonable
parameter set, and point to a strong dependence of the oscillator's potential
on the electrostatics of the island region. We propose that in a regime where
the electric field due to the bias voltage itself affects island position, a
"catastrophic" negative differential conductance (NDC) may be realized. This
effect is directly attributable to the magnitude of overlap of final and
initial quantum oscillator states, and as such represents experimental control
over quantum transitions of the oscillator via the macroscopically controllable
bias voltage.Comment: 6 pages, LaTex, 6 figure
Energetic Analysis of Magnetic Transitions in Ultra-small Nanoscopic Magnetic Rings
In this article, we report on experimental and theoretical investigations of
magnetic transitions in cobalt rings of size (diameter, width and thickness)
comparable to the exchange length of cobalt. Magnetization measurements were
performed for two sets of magnetic ring arrays: ultra-small magnetic rings
(outer diameter 13 nm, inner diameter 5nm and thickness 5 nm) and small
thin-walled magnetic rings (outer diameter 150 nm, width 5 nm and thickness 5
nm). This is the first report on the fabrication and magnetic properties of
such small rings. Our calculations suggest that if the magnetic ring's sizes
are comparable to, or smaller than, the exchange length of the magnetic
material, then only two magnetic states are important - the pure single domain
state and the flux closure vortex state. The onion-shape magnetic state does
not arise. Theoretical calculations are based on an energetic analysis of pure
and slightly distorted single domain and flux closure vortex magnetic states.
Based on the analytical calculations, a phase diagram is also derived for
ultra-small ring structures exhibiting the region for vortex magnetic state
formations as a function of material parameter.Comment: 10 pages, 15 figure
Magnetization Vorticity and Exchange Bias Phenomena in Arrays of Small Asymmetric Magnetic Rings
Arrays of nanoscopic magnetic asymmetric rings, 150 nm in outer diameter, are
fabricated using the techniques of electron-beam lithography, angular
deposition and ion-beam etching. Magnetic measurements for cobalt asymmetric
rings at room temperature verifies previous reports of vortex magnetic state
formation of a desired circulation direction for the application of external
magnetic field along the asymmetry axis of the rings. However, the main theme
of this article is the observation of exchange bias phenomena when the ring
samples are cooled down to low temperature in the presence of a positive
magnetic field. Very interestingly, the observed exchange bias effect is
negative for along and perpendicular orientations of ring's asymmetry axis with
respect to the in-plane external magnetic field. This is in good quantitative
agreement with the random interface model proposed by Malozemoff et al. For the
application of inplane external magnetic field at 45 degree with respect to the
asymmetry axis, the exchange bias effect is positive. Unlike the exchange bias
effects in thin films, this is a very unusual observation indicating that
exchange bias phenomena of opposite natures can be manipulated by appropriate
combination of geometrical constraint and external magnetic field direction, in
addition to the interfacial interactions between ferromagnetic (FM) and
antiferromagnetic (AFM) layer.Comment: Asymmetric magnetic rings arrays; Exchange bias phenomen
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