4,612 research outputs found
Large cone angle magnetization precession of an individual nanomagnet with dc electrical detection
We demonstrate on-chip resonant driving of large cone-angle magnetization
precession of an individual nanoscale permalloy element. Strong driving is
realized by locating the element in close proximity to the shorted end of a
coplanar strip waveguide, which generates a microwave magnetic field. We used a
microwave frequency modulation method to accurately measure resonant changes of
the dc anisotropic magnetoresistance. Precession cone angles up to are
determined with better than one degree of resolution. The resonance peak shape
is well-described by the Landau-Lifshitz-Gilbert equation
Exploring the causes of adverse events in hospitals and potential prevention strategies
Objectives
To examine the causes of adverse events
(AEs) and potential prevention strategies to minimise the
occurrence of AEs in hospitalised patients.
Methods
For the 744 AEs identified in the patient record
review study in 21 Dutch hospitals, trained reviewers
were asked to select all causal factors that contributed
to the AE. The results were analysed together with data
on preventability and consequences of AEs. In addition,
the reviewers selected one or more prevention strategies
for each preventable AE. The recommended prevention
strategies were analysed together with four general
causal categories: technical, human, organisational and
patient-related factors.
Results
Human causes were predominantly involved in
the causation of AEs (in 61% of the AEs), 61% of those
being preventable and 13% leading to permanent
disability. In 39% of the AEs, patient-related factors were
involved, in 14% organisational factors and in 4%
technical factors. Organisational causes contributed
relatively often to preventable AEs (93%) and AEs
resulting in permanent disability (20%). Recommended
strategies to prevent AEs were quality assurance/peer
review, evaluation of safety behaviour, training and
procedures. For the AEs with human and patient-related
causes, reviewers predominantly recommended quality
assurance/peer review. AEs caused by organisational
factors were considered preventable by improving
procedures.
Discussion
Healthcare interventions directed at human
causes are recommended because these play a large
role in AE causation. In addition, it seems worthwhile to
direct interventions on organisational causes because the
AEs they cause are nearly always believed to be
preventable. Organisational factors are thus relatively
easy to tackle. Future research designs should allow
researchers to interview healthcare providers that were
involved in the event, as an additional source of
information on contributing factors.
Unified description of bulk and interface-enhanced spin pumping
The dynamics of non-equilibrium spin accumulation generated in metals or
semiconductors by rf magnetic field pumping is treated within a diffusive
picture. The dc spin accumulation produced in a uniform system by a rotating
applied magnetic field or by a precessing magnetization of a weak ferromagnet
is in general given by a (small) fraction of hbar omega, where omega is the
rotation or precession frequency. With the addition of a neighboring,
field-free region and allowing for the diffusion of spins, the spin
accumulation is dramatically enhanced at the interface, saturating at the
universal value hbar omega in the limit of long spin relaxation time. This
effect can be maximized when the system dimensions are of the order of sqrt(2pi
D omega), where D is the diffusion constant. We compare our results to the
interface spin pumping theory of A. Brataas et al. [Phys. Rev. B 66, 060404(R)
(2002)]
Ion-sensing using chemically-modified ISFETs
Synthetic macrocyclic polyether ion receptors are the active components for the selective and sensitive detection of potassium ions in chemical sensors based on modified ISFETs.\ud
\ud
Covalent chemical anchoring of the sensing membrane to the gate oxide of the ISFET is essential in order to increase the lifetime of the sensor system to more than three months
On-chip detection of ferromagnetic resonance of a single submicron permalloy strip
We measured ferromagnetic resonance of a single submicron ferromagnetic
strip, embedded in an on-chip microwave transmission line device. The method
used is based on detection of the oscillating magnetic flux due to the
magnetization dynamics, with an inductive pick-up loop. The dependence of the
resonance frequency on applied static magnetic field agrees very well with the
Kittel formula, demonstrating that the uniform magnetization precession mode is
being driven
Adapting agriculture in 2050 in Flevoland; perspectives from stakeholders
Although recently more research has gone into farm level studies, little attention has been given to the variety of responses of farmers, considering their characteristics, objectives and the socio-economic, technological and political contexts (Reidsma et al, 2010). In the Agri-Adapt project we focus on farm level adaptation within an agricultural region considering the socio-economic context of 2050
Decoherence of Flux Qubits Coupled to Electronic Circuits
On the way to solid-state quantum computing, overcoming decoherence is the
central issue. In this contribution, we discuss the modeling of decoherence of
a superonducting flux qubit coupled to dissipative electronic circuitry. We
discuss its impact on single qubit decoherence rates and on the performance of
two-qubit gates. These results can be used for designing decoherence-optimal
setups.Comment: 16 pages, 5 figures, to appear in Advances in Solid State Physics,
Vol. 43 (2003
Split-gate quantum point contacts with tunable channel length
We report on developing split-gate quantum point contacts (QPCs) that have a
tunable length for the transport channel. The QPCs were realized in a
GaAs/AlGaAs heterostructure with a two- dimensional electron gas (2DEG) below
its surface. The conventional design uses 2 gate fingers on the wafer surface
which deplete the 2DEG underneath when a negative gate voltage is applied, and
this allows for tuning the width of the QPC channel. Our design has 6 gate
fingers and this provides additional control over the form of the electrostatic
potential that defines the channel. Our study is based on electrostatic
simulations and experiments and the results show that we developed QPCs where
the effective channel length can be tuned from about 200 nm to 600 nm.
Length-tunable QPCs are important for studies of electron many-body effects
because these phenomena show a nanoscale dependence on the dimensions of the
QPC channel
Polarization-preserving confocal microscope for optical experiments in a dilution refrigerator with high magnetic field
We present the design and operation of a fiber-based cryogenic confocal
microscope. It is designed as a compact cold-finger that fits inside the bore
of a superconducting magnet, and which is a modular unit that can be easily
swapped between use in a dilution refrigerator and other cryostats. We aimed at
application in quantum optical experiments with electron spins in
semiconductors and the design has been optimized for driving with, and
detection of optical fields with well-defined polarizations. This was
implemented with optical access via a polarization maintaining fiber together
with Voigt geometry at the cold finger, which circumvents Faraday rotations in
the optical components in high magnetic fields. Our unit is versatile for use
in experiments that measure photoluminescence, reflection, or transmission, as
we demonstrate with a quantum optical experiment with an ensemble of
donor-bound electrons in a thin GaAs film.Comment: 9 pages, 7 figure
- …