17,745 research outputs found
Realization of microwave quantum circuits using hybrid superconducting-semiconducting nanowire Josephson elements
We report the realization of quantum microwave circuits using hybrid
superconductor-semiconductor Josephson elements comprised of InAs nanowires
contacted by NbTiN. Capacitively-shunted single elements behave as transmon
qubits with electrically tunable transition frequencies. Two-element circuits
also exhibit transmon-like behavior near zero applied flux, but behave as flux
qubits at half the flux quantum, where non-sinusoidal current-phase relations
in the elements produce a double-well Josephson potential. These hybrid
Josephson elements are promising for applications requiring microwave
superconducting circuits operating in magnetic field.Comment: Main text: 4 pages, 4 figures; Supplement: 10 pages, 8 figures, 1
tabl
Tilt table testing, methodology and practical insights for the clinic.
Tilt table testing (TTT) has been used for decades to study short-term blood pressure (BP) and heart rate regulation during orthostatic challenges. TTT provokes vasovagal reflex in many syncope patients as a background of widespread use. Despite the availability of evidence-based practice syncope guidelines, proper application and interpretation of TTT in the day-to-day care of syncope patients remain challenging. In this review, we offer practical information on what is needed to perform TTT, how results should be interpreted including the Vasovagal Syncope International Study classification, why syncope induction on TTT is necessary in patients with unexplained syncope and on indications for TTT in syncope patient care. The minimum requirements to perform TTT are a tilt table with an appropriate tilt-down time, a continuous beat-to-beat BP monitor with at least three electrocardiogram leads and trained staff. We emphasize that TTT remains a valuable asset that adds to history building but cannot replace it, and highlight the importance of recognition when TTT is abnormal even without syncope. Acknowledgement by the patient/eyewitness of the reproducibility of the induced attack is mandatory in concluding a diagnosis. TTT may be indicated when the initial syncope evaluation does not yield a certain, highly likely, or possible diagnosis, but raises clinical suspicion of (1) reflex syncope, (2) orthostatic hypotension (OH), (3) postural orthostatic tachycardia syndrome or (4) psychogenic pseudosyncope. A therapeutic indication for TTT in the patient with a certain, highly likely or possible diagnosis of reflex syncope, may be to educate patients on prodromes. In patients with reflex syncope with OH TTT can be therapeutic to recognize hypotensive symptoms causing near-syncope to perform physical countermanoeuvres for syncope prevention (biofeedback). Detection of hypotensive susceptibility requiring therapy is of special value
Ethnic disparities in tuberculosis incidence and related factors among indigenous and other communities in ethnically diverse Suriname
Background: In Suriname, a country home to many ethnic groups, a high incidence of tuberculosis (TB) has been found among Indigenous Trio Amerindians. However, whether wider ethnic disparities in TB incidence and its associated risk factors (e.g., diabetes mellitus and HIV) exist in Suriname, is not known. We sought to investigate disparities in TB incidence and its risk factors on ethnicity in Suriname, as this could give way to targeted TB intervention programs. Methods: Anonymized patient data from 2011 to 2015 was extracted from the National TB Registry and analyzed. Differences in the five-year incidence rates of TB for the six largest ethnic groups-Creole, Hindustani, Indigenous, Javanese, Maroon, and Mixed-were assessed using a chi-square goodness-of-fit test, and TB patient differences regarding ethnicity were evaluated for selected factors using a multinomial logistic regression with Creole patients as reference. Results: 662 Patients were eligible for analyses with the following ethnic makeup: Creole (36.4%), Hindustani (15.6%), Indigenous (8.6%), Javanese (10.6%), Maroon (15.1%), and Mixed ethnicity (13.7%). Differences in five-year incidence rates for TB were significant, chi(2)(5, N = 662) = 244.42, p Conclusions: Our study has demonstrated that ethnic disparities in tuberculosis incidence exist in Suriname and that they are associated with specific, known risk factors such as HIV (especially for Creole people). For Indigenous people, risk factors may include diminished access to health care facilities and low socioeconomic status. However, direct data on these factors was unavailable. These findings call for targeted national intervention programs-with special attention given to the vulnerabilities of susceptible ethnic groups-and improved data collection
On the Hydrogen Atom via Wigner-Heisenberg Algebra
We extend the usual Kustaanheimo-Stiefel mapping to study and
discuss a constrained super-Wigner oscillator in four dimensions. We show that
the physical hydrogen atom is the system that emerges in the bosonic sector of
the mapped super 3D system.Comment: 14 pages, no figure. This work was initiated in collaboration with
Jambunatha Jayaraman (In memory), whose advises and encouragement were
fundamental. http://www.cbpf.b
Relativistic quantum mechanics of a Dirac oscillator
The Dirac oscillator is an exactly soluble model recently introduced in the
context of many particle models in relativistic quantum mechanics. The model
has been also considered as an interaction term for modelling quark confinement
in quantum chromodynamics. These considerations should be enough for
demonstrating that the Dirac oscillator can be an excellent example in
relativistic quantum mechanics. In this paper we offer a solution to the
problem and discuss some of its properties. We also discuss a physical picture
for the Dirac oscillator's non-standard interaction, showing how it arises on
describing the behaviour of a neutral particle carrying an anomalous magnetic
moment and moving inside an uniformly charged sphere.Comment: 19 pages, 1 figur
Dimming Supernovae without Cosmic Acceleration
We present a simple model where photons propagating in extra-galactic
magnetic fields can oscillate into very light axions. The oscillations may
convert some of the photons departing a distant supernova into axions, making
the supernova appear dimmer and hence more distant than it really is. Averaging
over different configurations of the magnetic field we find that the dimming
saturates at about 1/3 of the light from the supernovae at very large
redshifts. This results in a luminosity-distance vs. redshift curve almost
indistinguishable from that produced by the accelerating Universe, if the axion
mass and coupling scale are m ~ 10^-16 eV, M ~ 4 10^11 GeV. This phenomenon may
be an alternative to the accelerating Universe for explaining supernova
observations.Comment: 11 pages, LaTex, 2 figures included. Comments on effects of
refraction within galaxies and references adde
Interstellar dust in the BOOMERanG maps
Interstellar dust (ISD) emission is present in the mm-wave maps obtained by the BOOMERanG experiment at intermediate and high Galactic latitudes. We find that, while being sub-dominant at the lower frequencies (90,150, 240 GHz), thermal emission from ISD is dominant at 410 GHz, and is well correlated with the IRAS map at 100 µm. We find also that the angular power spectrum of ISD fluctuations at 410 GHz is a power law, and its level is negligible with respect to the angular power spectrum of the Cosmic Microwave Background (CMB) at 90 and 150 GHz
Brief review on semileptonic B decays
We concisely review semileptonic B decays, focussing on recent progress on
both theoretical and experimental sides.Comment: 18 pages, 2 figures; version to be published in Mod. Phys. Lett.
Cosmological Parameters from the 2003 flight of BOOMERANG
We present the cosmological parameters from the CMB intensity and
polarization power spectra of the 2003 Antarctic flight of the BOOMERANG
telescope. The BOOMERANG data alone constrains the parameters of the
CDM model remarkably well and is consistent with constraints from a
multi-experiment combined CMB data set. We add LSS data from the 2dF and SDSS
redshift surveys to the combined CMB data set and test several extensions to
the standard model including: running of the spectral index, curvature, tensor
modes, the effect of massive neutrinos, and an effective equation of state for
dark energy. We also include an analysis of constraints to a model which allows
a CDM isocurvature admixture.Comment: 18 pages, 10 figures, submitted to Ap
Testing the Cosmic Coincidence Problem and the Nature of Dark Energy
Dark energy models which alter the relative scaling behavior of dark energy
and matter could provide a natural solution to the cosmic coincidence problem -
why the densities of dark energy and dark matter are comparable today. A
generalized class of dark energy models is introduced which allows
non-canonical scaling of the ratio of dark matter and dark energy with the
Robertson-Walker scale factor a(t). Upcoming observations, such as a high
redshift supernova survey, application of the Alcock-Paczynski test to quasar
pairs, and cluster evolution, will strongly constrain the relative scaling of
dark matter and dark energy as well as the equation of state of the dark
energy. Thus, whether there actually is a coincidence problem, and the extent
of cosmic coincidence in the universe's recent past can be answered
observationally in the near future. Determining whether today is a special time
in the history of the universe will be a SNAP.Comment: 5 pages, 3 figures, revtex4, submitted to PR
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