2,110 research outputs found
Long Distance Transport of Ultracold Atoms using a 1D optical lattice
We study the horizontal transport of ultracold atoms over macroscopic
distances of up to 20 cm with a moving 1D optical lattice. By using an optical
Bessel beam to form the optical lattice, we can achieve nearly homogeneous
trapping conditions over the full transport length, which is crucial in order
to hold the atoms against gravity for such a wide range. Fast transport
velocities of up to 6 m/s (corresponding to about 1100 photon recoils) and
accelerations of up to 2600 m/s2 are reached. Even at high velocities the
momentum of the atoms is precisely defined with an uncertainty of less than one
photon recoil. This allows for construction of an atom catapult with high
kinetic energy resolution, which might have applications in novel collision
experiments.Comment: 15 pages, 8 figure
Fractal Conductance Fluctuations in Gold--Nanowires
A detailed analysis of magneto-conductance fluctuations of quasiballistic
gold-nanowires of various lengths is presented. We find that the variance
when analyzed for much
smaller than the correlation field varies according to with indicating that the graph of
vs. is fractal. We attribute this behavior to the existence of
long-lived states arising from chaotic trajectories trapped close to regular
classical orbits. We find that decreases with increasing length of the
wires.Comment: 5 pages, Revtex with epsf, 4 Postscript figures, final version
accepted as Phys. Rev. Let
Conductance fluctuations in mesoscopic normal-metal/superconductor samples
We study the magnetoconductance fluctuations of mesoscopic
normal-metal/superconductor (NS) samples consisting of a gold-wire in contact
with a niobium film. The magnetic field strength is varied over a wide range,
including values that are larger than the upper critical field B_c2 of niobium.
In agreement with recent theoretical predictions we find that in the NS sample
the rms of the conductance fluctuations (CF) is by a factor of 2.8 +/- 0.4
larger than in the high field regime where the entire system is driven normal
conducting. Further characteristics of the CF are discussed.Comment: 4 pages, REVTEX, 3 eps-figures included. To be published in Phys.
Rev. Lett.. Changes: one misplaced figure correcte
Attention Deficit Hyperactivity Disorder: Is There an App for That? Suitability Assessment of Apps for Children and Young People With ADHD
Background: Attention-deficit/hyperactivity disorder (ADHD) is a complex highly comorbid disorder, which can have a huge impact on those with ADHD, their family, and the community around them. ADHD is currently managed using pharmacological and nonpharmacological interventions. However, with advances in technology and an increase in the use of mobile apps, managing ADHD can be augmented using apps specifically designed for this population. However, little is known regarding the suitability and usability of currently available apps. Objective: The aim of this study was to explore the suitability of the top 10 listed apps for children and young people with ADHD and clinicians who work with them. It is hypothesized that mobile apps designed for this population could be more suitably designed for this population. Methods: The top 10 listed apps that are specifically targeted toward children and young people with ADHD in the United Kingdom were identified via the Google Play (n=5) and iTunes store (n=5). Interviews were then undertaken with 5 clinicians who specialize in treating this population and 5 children and young people with ADHD themselves, to explore their opinions of the 10 apps identified and what they believe the key components are for apps to be suitable for this population. Results: Five themes emerged from clinician and young people interviews: the accessibility of the technology, the importance of relating to apps, addressing ADHD symptoms and related difficulties, age appropriateness, and app interaction. Three additional themes emerged from the clinician interviews alone: monitoring symptoms, side effects and app effect on relationships, and the impact of common comorbid conditions. The characteristics of the apps did not appear to match well with the views of our sample. Conclusions: These findings suggest that the apps may not be suitable in meeting the complex needs associated with this condition. Further research is required to explore the value of apps for children and young people with ADHD and their families and, in particular, any positive role for apps in the management of ADHD in this age group. A systematic review on how technology can be used to engage this population and how it can be used to help them would be a useful way forward. This could be the platform to begin exploring the use of apps further
Patient engagement with antibiotic messaging in secondary care: a qualitative feasibility study of the ‘review & revise’ experience
Background: We aimed to investigate and optimise the acceptability and usefulness of a patient leaflet about antibiotic prescribing decisions made during hospitalisation, and to explore individual patient experiences and preferences regarding the process of antibiotic prescription ‘review & revise’ which is a key strategy to minimise antibiotic overuse in hospitals.
Methods: In this qualitative study, run within the feasibility study of a large, cluster-randomised stepped wedge trial of 36 hospital organisations, a series of semi-structured, think-aloud telephone interviews were conducted and data were analysed using thematic analysis. Fifteen adult patients who had experienced a recent acute medical hospital admission during which they had been prescribed antimicrobials and offered a patient leaflet about antibiotic prescribing were recruited to the study.
Results: Participants reacted positively to the leaflet, reporting that it was both an accessible and important source of information which struck the appropriate balance between informing and reassuring. Participants all valued open communication with clinicians, and were keen to be involved in antibiotic prescribing decisions, with individuals reporting positive experiences regarding antibiotic prescription changes or stopping. Many participants had prior experience or knowledge of antibiotics and resistance, and generally welcomed efforts to reduce antibiotic usage. Overall, there was a feeling that healthcare professionals (HCPs) are trusted experts providing the most appropriate treatment for individual patient conditions.
Conclusions: This study offers novel insights into how patients within secondary care are likely to respond to messages advocating a reduction in the use of antibiotics through the ‘review & revise’ approach. Due to the level of trust that patients place in their care provider, encouraging HCPs within secondary care to engage patients with greater communication and information provision could provide great advantages in the drive to reduce antibiotic use. It may also be beneficial for HCPs to view patient experiences as cumulative events that have the potential to impact future behaviour around antibiotic use. Finally, pre-testing messages about antibiotic prescribing and resistance is vital to dispelling any misconceptions either around effectiveness of treatment for patients, or perceptions of how messages may be received
Strong electron-phonon coupling in delta-phase stabilized Pu
Heat capacity measurements of the delta-phase stabilized alloy Pu-Al suggest
that strong electron-phonon coupling is required to explain the moderate
renormalization of the electronic density of states near the Fermi energy. We
calculate the heat capacity contributions from the lattice and electronic
degrees of freedom as well as from the electron-lattice coupling term and find
good overall agreement between experiment and theory assuming a dimensionless
electron-phonon coupling parameter of order unity, lambda ~ 0.8. This large
electron-phonon coupling parameter is comparable to reported values in other
superconducting metals with face-centered cubic crystal structure, for example,
Pd (lambda ~ 0.7) and Pb (lambda ~ 1.5). Further, our analysis shows evidence
of a sizable residual low-temperature entropy contribution, S_{res} ~ 0.4 k_B
(per atom). We can fit the residual specific heat to a two-level system.
Therefore, we speculate that the observed residual entropy originates from
crystal-electric field effects of the Pu atoms or from self-irradiation induced
defects frozen in at low temperatures.Comment: 9 pages, 11 figures, to appear in Phys. Rev.
Speech Communication
Contains research objectives and reports on three research projects.U.S. Air Force (Air Force Cambridge Research Center, Air Research and Development Command) under Contract AF19(604)-6102National Science Foundatio
Magnetic state of plutonium ion in metallic Pu and its compounds
By LDA+U method with spin-orbit coupling (LDA+U+SO) the magnetic state and
electronic structure have been investigated for plutonium in \delta and \alpha
phases and for Pu compounds: PuN, PuCoGa5, PuRh2, PuSi2, PuTe, and PuSb. For
metallic plutonium in both phases in agreement with experiment a nonmagnetic
ground state was found with Pu ions in f^6 configuration with zero values of
spin, orbital, and total moments. This result is determined by a strong
spin-orbit coupling in 5f shell that gives in LDA calculation a pronounced
splitting of 5f states on f^{5/2} and f^{7/2} subbands. A Fermi level is in a
pseudogap between them, so that f^{5/2} subshell is already nearly completely
filled with six electrons before Coulomb correlation effects were taken into
account. The competition between spin-orbit coupling and exchange (Hund)
interaction (favoring magnetic ground state) in 5f shell is so delicately
balanced, that a small increase (less than 15%) of exchange interaction
parameter value from J_H=0.48eV obtained in constrain LDA calculation would
result in a magnetic ground state with nonzero spin and orbital moment values.
For Pu compounds investigated in the present work, predominantly f^6
configuration with nonzero magnetic moments was found in PuCoGa5, PuSi2, and
PuTe, while PuN, PuRh2, and PuSb have f^5 configuration with sizeable magnetic
moment values. Whereas pure jj coupling scheme was found to be valid for
metallic plutonium, intermediate coupling scheme is needed to describe 5f shell
in Pu compounds. The results of our calculations show that both spin-orbit
coupling and exchange interaction terms in the Hamiltonian must be treated in a
general matrix form for Pu and its compounds.Comment: 20 pages, LaTeX; changed discussion on reference pape
Photoassociation of sodium in a Bose-Einstein condensate
We report on the formation of ultra-cold Na molecules using single-photon
photoassociation of a Bose-Einstein condensate. The photoassociation rate,
linewidth and light shift of the J=1, vibrational level of the
\mterm{A}{1}{+}{u} molecular bound state have been measured. We find that the
photoassociation rate constant increases linearly with intensity, even where it
is predicted that many-body effects might limit the rate. Our observations are
everywhere in good agreement with a two-body theory having no free parameters.Comment: Fixes to the figures and references. Just the normal human stupidity
type stuff, nothing Earth-shatterin
Superconducting Proximity Effect and Universal Conductance Fluctuations
We examine universal conductance fluctuations (UCFs) in mesoscopic
normal-superconducting-normal (N-S-N) structures using a numerical solution of
the Bogoliubov - de Gennes equation. We discuss two cases depending on the
presence (``open'' structure) or absence (``closed'' structure) of
quasiparticle transmission. In contrast to N-S structures, where the onset of
superconductivity increases fluctuations, we find that UCFs are suppressed by
superconductivity for N-S-N structures. We demonstrate that the fluctuations in
``open'' and ``closed'' structures exhibit distinct responses to an applied
magnetic field and to an imposed phase variation of the superconducting order
parameter.Comment: (4 pages, 5 figures). Corrected typos in equations, added references,
changed Fig. 5 and its discussions. Phys. Rev. B, accepted for publicatio
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