1,147 research outputs found
Analysis and study of hospital communication via social media from the patient perspective
Currently, the online interaction between citizens and hospitals is poor, as
users believe that there are shortcomings that could be improved. This study
analyzes patients’ opinions of the online communication strategies of hospitals in
Spain. Therefore, a mixed-method is proposed. Firstly, a qualitative analysis through
a focus-group was carried out, so around twenty representatives of national,
regional and local patients’ associations were brought together. Secondly, the
research is supplemented with a content assessment of the Twitter activity of the
most influential hospitals in Spain. The results reveal that the general public
appreciate hospitals’ communication potential through social media, although they
are generally unaware of how it works. The group says that, apart from the lack of
interaction, they find it hard to understand certain messages, and some publications
give a biased picture. In order to improve communication, patients and
relatives are demanding that their perspective be taken into consideration in the
messages issued to enhance the quality of life and well-being of society
Control of Material Damping in High-Q Membrane Microresonators
We study the mechanical quality factors of bilayer aluminum/silicon-nitride
membranes. By coating ultrahigh-Q Si3N4 membranes with a more lossy metal, we
can precisely measure the effect of material loss on Q's of tensioned resonator
modes over a large range of frequencies. We develop a theoretical model that
interprets our results and predicts the damping can be reduced significantly by
patterning the metal film. Using such patterning, we fabricate Al-Si3N4
membranes with ultrahigh Q at room temperature. Our work elucidates the role of
material loss in the Q of membrane resonators and informs the design of hybrid
mechanical oscillators for optical-electrical-mechanical quantum interfaces
Bose-Einstein condensation in a circular waveguide
We have produced Bose-Einstein condensates in a ring-shaped magnetic
waveguide. The few-millimeter diameter non-zero bias ring is formed from a
time-averaged quadrupole ring. Condensates which propagate around the ring make
several revolutions within the time it takes for them to expand to fill the
ring. The ring shape is ideally suited for studies of vorticity in a
multiply-connected geometry and is promising as a rotation sensor.Comment: 4 pages, 4 figure
Collimated, single-pass atom source from a pulsed alkali metal dispenser for laser-cooling experiments
We have developed an improved scheme for loading atoms into a magneto-optical
trap (MOT) from a directed alkali metal dispenser in < 10^-10 torr ultra-high
vacuum conditions. A current-driven dispenser was surrounded with a cold
absorbing "shroud" held at < 0 C, pumping rubidium atoms not directed into the
MOT. This nearly eliminates background alkali atoms and reduces the detrimental
rise in pressure normally associated with these devices. The system can be
well-described as a current-controlled, rapidly-switched, two-temperature
thermal beam, and was used to load a MOT with 3 x 10^8 atoms.Comment: 5 pages, 4 figure
Manifestation of classical wave delays in a fully quantized model of the scattering of a single photon
We consider a fully quantized model of spontaneous emission, scattering, and
absorption, and study propagation of a single photon from an emitting atom to a
detector atom both with and without an intervening scatterer. We find an exact
quantum analog to the classical complex analytic signal of an electromagnetic
wave scattered by a medium of charged oscillators. This quantum signal exhibits
classical phase delays. We define a time of detection which, in the appropriate
limits, exactly matches the predictions of a classically defined delay for
light propagating through a medium of charged oscillators. The fully quantized
model provides a simple, unambiguous, and causal interpretation of delays that
seemingly imply speeds greater than c in the region of anomalous dispersion.Comment: 18 pages, 4 figures, revised for clarity, typos corrrecte
Tunable Cavity Optomechanics with Ultracold Atoms
We present an atom-chip-based realization of quantum cavity optomechanics
with cold atoms localized within a Fabry-Perot cavity. Effective sub-wavelength
positioning of the atomic ensemble allows for tuning the linear and quadratic
optomechanical coupling parameters, varying the sensitivity to the displacement
and strain of a compressible gaseous cantilever. We observe effects of such
tuning on cavity optical nonlinearity and optomechanical frequency shifts,
providing their first characterization in the quadratic-coupling regime.Comment: 4 pages, 5 figure
Cavity optomechanics with Si3N4 membranes at cryogenic temperatures
We describe a cryogenic cavity-optomechanical system that combines Si3N4
membranes with a mechanically-rigid Fabry-Perot cavity. The extremely high
quality-factor frequency products of the membranes allow us to cool a MHz
mechanical mode to a phonon occupation of less than 10, starting at a bath
temperature of 5 kelvin. We show that even at cold temperatures
thermally-occupied mechanical modes of the cavity elements can be a limitation,
and we discuss methods to reduce these effects sufficiently to achieve ground
state cooling. This promising new platform should have versatile uses for
hybrid devices and searches for radiation pressure shot noise.Comment: 19 pages, 5 figures, submitted to New Journal of Physic
Advancing the Scholarship of Teaching Through Collaborative Self-Study
Self-study research is a mode of scholarly inquiry in which teachers examine their beliefs and actions as educators and explore pedagogical questions. A three-phase model of collaborative self-study research is offered as a framework for university faculty to engage in self-study for the purpose of improving teaching and creating new knowledge
Tensile strained membranes for cavity optomechanics
We investigate the optomechanical properties of tensile-strained ternary
InGaP nanomembranes grown on GaAs. This material system combines the benefits
of highly strained membranes based on stoichiometric silicon nitride, with the
unique properties of thin-film semiconductor single crystals, as previously
demonstrated with suspended GaAs. Here we employ lattice mismatch in epitaxial
growth to impart an intrinsic tensile strain to a monocrystalline thin film
(approximately 30 nm thick). These structures exhibit mechanical quality
factors of 2*10^6 or beyond at room temperature and 17 K for eigenfrequencies
up to 1 MHz, yielding Q*f products of 2*10^12 Hz for a tensile stress of ~170
MPa. Incorporating such membranes in a high finesse Fabry-Perot cavity, we
extract an upper limit to the total optical loss (including both absorption and
scatter) of 40 ppm at 1064 nm and room temperature. Further reductions of the
In content of this alloy will enable tensile stress levels of 1 GPa, with the
potential for a significant increase in the Q*f product, assuming no
deterioration in the mechanical loss at this composition and strain level. This
materials system is a promising candidate for the integration of strained
semiconductor membrane structures with low-loss semiconductor mirrors and for
realizing stacks of membranes for enhanced optomechanical coupling.Comment: 10 pages, 3 figure
Ponderomotive light squeezing with atomic cavity optomechanics
Accessing distinctly quantum aspects of the interaction between light and the
position of a mechanical object has been an outstanding challenge to
cavity-optomechanical systems. Only cold-atom implementations of cavity
optomechanics have indicated effects of the quantum fluctuations in the optical
radiation pressure force. Here we use such a system, in which quantum
photon-number fluctuations significantly drive the center of mass of an atomic
ensemble inside a Fabry-Perot cavity. We show that the optomechanical response
both amplifies and ponderomotively squeezes the quantum light field. We also
demonstrate that classical optical fluctuations can be attenuated by 26 dB or
amplified by 20 dB with a weak input pump power of < 40 pW, and characterize
the optomechanical amplifier's frequency-dependent gain and phase response in
both the amplitude and phase-modulation quadratures
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