2,303 research outputs found
Universality of Hofstadter butterflies on hyperbolic lattices
Motivated by recent experimental breakthroughs in realizing hyperbolic
lattices in superconducting waveguides and electric circuits, we compute the
Hofstadter butterfly on regular hyperbolic tilings. By utilizing large
hyperbolic lattices with periodic boundary conditions, we obtain the true
hyperbolic bulk spectrum that is unaffected by contributions from boundary
states. Our results reveal that the butterfly spectrum with large extended
gapped regions prevails and that its shape is universally determined by the
number of edges of the fundamental tile, while the fractal structure is lost in
such a non-Euclidean case. We explain how these intriguing features are related
to the nature of Landau levels in hyperbolic space, and how they could be
verified experimentally.Comment: 4 pages, 3 figures + supplementar
An Exploratory Factor Analysis of the Negative Effects Questionnaire for Monitoring and Reporting Adverse and Unwanted Events
Research conducted during the last decades has provided increasing evidence
for the use of psychological treatments for a number of psychiatric disorders
and somatic complaints. However, by focusing only on the positive outcomes,
less attention has been given to the potential of negative effects. Despite
indications of deterioration and other adverse and unwanted events during
treatment, little is known about their occurrence and characteristics. Hence,
in order to facilitate research of negative effects, a new instrument for
monitoring and reporting their incidence and impact was developed using a
consensus among researchers, self-reports by patients, and a literature
review: the Negative Effects Questionnaire. Participants were recruited via a
smartphone-delivered self-help treatment for social anxiety disorder and
through the media (N = 653). An exploratory factor analysis was performed,
resulting in a six-factor solution with 32 items, accounting for 57.64% of the
variance. The derived factors were: symptoms, quality, dependency, stigma,
hopelessness, and failure. Items related to unpleasant memories, stress, and
anxiety were experienced by more than one-third of the participants. Further,
increased or novel symptoms, as well as lack of quality in the treatment and
therapeutic relationship rendered the highest self-reported negative impact.
In addition, the findings were discussed in relation to prior research and
other similar instruments of adverse and unwanted events, giving credence to
the items that are included. The instrument is presently available in eleven
different languages and can be freely downloaded and used from
www.neqscale.com
Observations upon the structure and normal contents of the ductus and saccus endolymphaticus in the Guinea-pig (Cavia cobaya)
No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49600/1/1000390102_ftp.pd
Reduction of Two-Dimensional Dilute Ising Spin Glasses
The recently proposed reduction method is applied to the Edwards-Anderson
model on bond-diluted square lattices. This allows, in combination with a
graph-theoretical matching algorithm, to calculate numerically exact ground
states of large systems. Low-temperature domain-wall excitations are studied to
determine the stiffness exponent y_2. A value of y_2=-0.281(3) is found,
consistent with previous results obtained on undiluted lattices. This
comparison demonstrates the validity of the reduction method for bond-diluted
spin systems and provides strong support for similar studies proclaiming
accurate results for stiffness exponents in dimensions d=3,...,7.Comment: 7 pages, RevTex4, 6 ps-figures included, for related information, see
http://www.physics.emory.edu/faculty/boettcher
Optimal Vertex Cover for the Small-World Hanoi Networks
The vertex-cover problem on the Hanoi networks HN3 and HN5 is analyzed with
an exact renormalization group and parallel-tempering Monte Carlo simulations.
The grand canonical partition function of the equivalent hard-core repulsive
lattice-gas problem is recast first as an Ising-like canonical partition
function, which allows for a closed set of renormalization group equations. The
flow of these equations is analyzed for the limit of infinite chemical
potential, at which the vertex-cover problem is attained. The relevant fixed
point and its neighborhood are analyzed, and non-trivial results are obtained
both, for the coverage as well as for the ground state entropy density, which
indicates the complex structure of the solution space. Using special
hierarchy-dependent operators in the renormalization group and Monte-Carlo
simulations, structural details of optimal configurations are revealed. These
studies indicate that the optimal coverages (or packings) are not related by a
simple symmetry. Using a clustering analysis of the solutions obtained in the
Monte Carlo simulations, a complex solution space structure is revealed for
each system size. Nevertheless, in the thermodynamic limit, the solution
landscape is dominated by one huge set of very similar solutions.Comment: RevTex, 24 pages; many corrections in text and figures; final
version; for related information, see
http://www.physics.emory.edu/faculty/boettcher
Realizing efficient topological temporal pumping in electrical circuits
Quantized adiabatic transport can occur when a system is slowly modulated
over time. In most realizations however, the efficiency of such transport is
reduced by unwanted dissipation, back-scattering, and non-adiabatic effects. In
this work, we realize a topological adiabatic pump in an electrical circuit
network that supports remarkably stable and long-lasting pumping of a voltage
signal. We further characterize the topology of our system by deducing the
Chern number from the measured edge band structure. To achieve this, the
experimental setup makes use of active circuit elements that act as
time-variable voltage-controlled inductors.Comment: main (5 pages, 3 figures) plus supplement (8 pages, 4 figures
Random walk on disordered networks
Random walks are studied on disordered cellular networks in 2-and
3-dimensional spaces with arbitrary curvature. The coefficients of the
evolution equation are calculated in term of the structural properties of the
cellular system. The effects of disorder and space-curvature on the diffusion
phenomena are investigated. In disordered systems the mean square displacement
displays an enhancement at short time and a lowering at long ones, with respect
to the ordered case. The asymptotic expression for the diffusion equation on
hyperbolic cellular systems relates random walk on curved lattices to
hyperbolic Brownian motion.Comment: 10 Pages, 3 Postscript figure
Expected Basal Insulin Requirement during CSII therapy by Age Group, Sex and BMI, based on 25,718 Young People with Type 1 Diabetes in the DPV Registry.
Background Since the introduction of insulin pumps into the therapy of paediatric subjects, different approaches have been taken to find optimal basal rates. Previously, the DPV registry provided circadian basal rate patterns for different age groups. As the number of pump users has increased recently and short-acting insulin analogues are now predominant, we performed a new analysis with a larger data pool. Methods We included all recent basal profiles from T1D patients between 1 and 25 years from the DPV 2021 data pool. We excluded night-time-only pump users, human regular insulin users, and daily basal rates 1.0 U/kgBW/d. Results In the analysis of profiles from 25,718 young persons with T1D, differences in the daily pattern of basal rates were found between age groups. In addition, we saw significant (p<0.001) differences in total daily basal dose between genders in all age groups except adults. In addition, the shape of the expected basal-rate pattern differed by BMI, HbA1c and use of continuous glucose monitoring. Discussion This analysis demonstrates multiple factors influencing basal patterns and insulin requirement, including age group, gender, overweight, HbA1c, bolus frequency and sensor use. As circadian basal rates are still mandatory for initiating insulin pump therapy with or without automation, a multimodal approach is necessary to estimate optimal basal rates
Negative Effects of Internet Interventions: A Qualitative Content Analysis of Patients' Experiences with Treatments Delivered Online
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