46,011 research outputs found
Compact modes in quasi one dimensional coupled magnetic oscillators
In this work we study analytically and numerically the spectrum and
localization properties of three quasi-one-dimensional (ribbons) split-ring
resonator arrays which possess magnetic flatbands, namely, the stub, Lieb and
kagome lattices, and how their spectra is affected by the presence of
perturbations that break the delicate geometrical interference needed for a
magnetic flatband to exist. We find that the Stub and Lieb ribbons are stable
against the three types of perturbations considered here, while the kagome
ribbon is, in general, unstable. When losses are incorporated, all flatbands
remain dispersionless but become complex, with the kagome ribbon exhibiting the
highest loss rate.Comment: 11 pages, 15 figure
Quasinormal frequencies of asymptotically flat two-dimensional black holes
We discuss whether the minimally coupled massless Klein-Gordon and Dirac
fields have well defined quasinormal modes in single horizon, asymptotically
flat two-dimensional black holes. To get the result we solve the equations of
motion in the massless limit and we also calculate the effective potentials of
Schrodinger type equations. Furthermore we calculate exactly the quasinormal
frequencies of the Dirac field propagating in the two-dimensional uncharged
Witten black hole. We compare our results on its quasinormal frequencies with
other already published.Comment: 12 pages. Accepted for publication in Gen. Rel. and Gra
Zeeman-type dragging in the Kerr--Newman and NUT spacetimes
In this communication we discuss two distinct Zeeman-type gravitomagnetic
effects deserving attention since they can be easily characterized in their
exact form, not via approximation procedures. Some observations are also made
on gravitoelectric effects.Comment: 5 pages, a talk delivered at the 11th Marcel Grossmann Meeting (2006
A Layman's guide to SUSY GUTs
The determination of the most straightforward evidence for the existence of
the Superworld requires a guide for non-experts (especially experimental
physicists) for them to make their own judgement on the value of such
predictions. For this purpose we review the most basic results of Super-Grand
unification in a simple and clear way. We focus the attention on two specific
models and their predictions. These two models represent an example of a direct
comparison between a traditional unified-theory and a string-inspired approach
to the solution of the many open problems of the Standard Model. We emphasize
that viable models must satisfy {\em all} available experimental constraints
and be as simple as theoretically possible. The two well defined supergravity
models, and , can be described in terms of only a few
parameters (five and three respectively) instead of the more than twenty needed
in the MSSM model, \ie, the Minimal Supersymmetric extension of the Standard
Model. A case of special interest is the strict no-scale
supergravity where all predictions depend on only one parameter (plus the
top-quark mass). A general consequence of these analyses is that supersymmetric
particles can be at the verge of discovery, lurking around the corner at
present and near future facilities. This review should help anyone distinguish
between well motivated predictions and predictions based on arbitrary choices
of parameters in undefined models.Comment: 25 pages, Latex, 11 figures (not included), CERN-TH.7077/93,
CTP-TAMU-65/93. A complete ps file (1.31MB) with embedded figures is
available by request from [email protected]
Heart Rate Extraction from Novel Neck Photoplethysmography Signals.
This paper demonstrates for the first time how heart rate (HR) can be extracted from novel neck photoplethysmography (PPG). A novel algorithm is presented, which when tested in neck PPG signals recorded from 9 subjects at different respiratory rates, obtained good precision with respect to gold standard ECG signals. Mean absolute error (MAE), standard deviation error (SDAE) and root-mean-square error (RMSE) resulted in 1.22, 1.54 and 1.98 beats per minute (BPM), respectively. HRneck estimation showed strong correlation (R=0.94) with reference HRECG. Good agreement between both techniques was also demonstrated by Bland-Altman analysis. The bias between mean HR paired differences was -0.16 BPM and 95% limits of agreement (LoA) were (-4.7, 4.4). Comparatively, for widely used finger PPG, errors were slightly smaller (MAE=0.38 BPM, SDAE=0.48 BPM, RMSE=0.62BPM) and the correlation with reference ECG was also very close to 1 (R=0.99). Bias of -0.04 BPM and 95% LoA (-1.5, 1.4), also showed high degree of agreement. However, these findings show the potential the neck could have as an alternative body location for wearable monitors, aiming to reduce the number of sensing sites whilst still providing access to a wide variety of physiological parameters
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