513 research outputs found
Characterization of persistent atrial fibrillation with nonâcontact charge density mapping and relationship to voltage
Background
Despite studies using localized high density contact mapping and lower resolution panoramic approaches, the mechanisms that sustain human persistent atrial fibrillation (AF) remain unresolved. Voltage mapping is commonly employed as a surrogate of atrial substrate to guide ablation procedures.
Objective
To study the distribution and temporal stability of activation during persistent AF using a global non-contact charge density approach and compare the findings with bipolar contact mapping.
Methods
Patients undergoing either redo or de novo ablation for persistent AF underwent charge density and voltage mapping to guide the ablation procedure. Offline analysis was performed to measure the temporal stability of three specific charge density activation (CDA) patterns, and the degree of spatial overlap between CDA patterns and low voltage regions.
Results
CDA was observed in patient-specific locations that partially overlapped, comprising local rotational activity (18% of LA), local irregular activity (41% of LA), and focal activity (39% of LA). Local irregular activity had the highest temporal stability. LA voltage was similar in regions with and without CDA.
Conclusion
In persistent AF, CDA patterns appear unrelated to low voltage areas but occur in varying locations with high temporal stability
Radiofrequency ablation of ventricular tachycardia in AndersonâFabry disease : a case series
Background
Cardiac involvement in AndersonâFabry disease (AFD) can lead to arrhythmia, including ventricular tachycardia (VT). The literature on radiofrequency ablation (RFA) for the treatment of VT in AFD disease is limited.
Case summary
We discuss RFA of drug-refractory VT electrical storm in three males with AFD. The first patient (53âyears old) had extensive involvement of the inferolateral left ventricle (LV) demonstrated with cardiac magnetic resonance imaging (CMRI), with a left ventricular ejection fraction (LVEF) of 35%. Two VT ablation procedures were performed. At the first procedure, the inferobasal endocardial LV was ablated. Furthermore, VT prompted a second ablation, where epicardial and endocardial sites were ablated. The acute arrhythmia burden was controlled but he died 4 months later despite appropriate implantable cardioverter-defibrillator therapies for VT. The second patient (67âyears old) had full-thickness inferolateral involvement demonstrated with CMRI and LVEF of 45%. RFA of several endocardial left ventricular sites was performed. Over a 3-year follow-up, only brief non-sustained VT was identified, but he subsequently died of cardiac failure. Our third patient (69âyears old), had an LVEF of 35%. He had RFA of endocardial left ventricular apical disease, but died 3 weeks later of cardiac failure.
Discussion
RFA of drug-refractory VT in AFD is feasible using standard electrophysiological mapping and ablation techniques, although the added clinical benefit is of questionable value. VT storm in the context of AFD may be a marker of end-stage disease
Decaying Dark Matter can explain the electron/positron excesses
PAMELA and ATIC recently reported excesses in e+ e- cosmic rays. Since the
interpretation in terms of DM annihilations was found to be not easily
compatible with constraints from photon observations, we consider the DM decay
hypothesis and find that it can explain the e+ e- excesses compatibly with all
constraints, and can be tested by dedicated HESS observations of the Galactic
Ridge. ATIC data indicate a DM mass of about 2 TeV: this mass naturally implies
the observed DM abundance relative to ordinary matter if DM is a quasi-stable
composite particle with a baryon-like matter asymmetry. Technicolor naturally
yields these type of candidates.Comment: 20 pages, 7 figure
Vortex dynamics and states of artificially layered superconducting films with correlated defects
Linear resistances and -characteristics have been measured over a wide
range in the parameter space of the mixed phase of multilayered a-TaGe/Ge
films. Three films with varying interlayer coupling and correlated defects
oriented at an angle from the film normal were investigated.
Experimental data were analyzed within vortex glass models and a second order
phase transition from a resistive vortex liquid to a pinned glass phase.
Various vortex phases including changes from three to two dimensional behavior
depending on anisotropy have been identified. Careful analysis of
-characteristics in the glass phases revealed a distinctive and
-dependence of the glass exponent . The vortex dynamics in the
Bose-glass phase does not follow the predicted behavior for excitations of
vortex kinks or loops.Comment: 16 pages, 10 figures, 3 table
Gamma-ray and radio tests of the e+e- excess from DM annihilations
PAMELA and ATIC recently reported an excess in e+e- cosmic rays. We show that
if it is due to Dark Matter annihilations, the associated gamma-ray flux and
the synchrotron emission produced by e+e- in the galactic magnetic field
violate HESS and radio observations of the galactic center and HESS
observations of dwarf Spheroidals, unless the DM density profile is
significantly less steep than the benchmark NFW and Einasto profiles.Comment: 16 pages, 4 figures; v2: normalizations fixed in Table 2 and typos
corrected (no changes in the analysis nor the results), some references and
comments added; v3: minor additions, matches published versio
From Social Data Mining to Forecasting Socio-Economic Crisis
Socio-economic data mining has a great potential in terms of gaining a better
understanding of problems that our economy and society are facing, such as
financial instability, shortages of resources, or conflicts. Without
large-scale data mining, progress in these areas seems hard or impossible.
Therefore, a suitable, distributed data mining infrastructure and research
centers should be built in Europe. It also appears appropriate to build a
network of Crisis Observatories. They can be imagined as laboratories devoted
to the gathering and processing of enormous volumes of data on both natural
systems such as the Earth and its ecosystem, as well as on human
techno-socio-economic systems, so as to gain early warnings of impending
events. Reality mining provides the chance to adapt more quickly and more
accurately to changing situations. Further opportunities arise by individually
customized services, which however should be provided in a privacy-respecting
way. This requires the development of novel ICT (such as a self- organizing
Web), but most likely new legal regulations and suitable institutions as well.
As long as such regulations are lacking on a world-wide scale, it is in the
public interest that scientists explore what can be done with the huge data
available. Big data do have the potential to change or even threaten democratic
societies. The same applies to sudden and large-scale failures of ICT systems.
Therefore, dealing with data must be done with a large degree of responsibility
and care. Self-interests of individuals, companies or institutions have limits,
where the public interest is affected, and public interest is not a sufficient
justification to violate human rights of individuals. Privacy is a high good,
as confidentiality is, and damaging it would have serious side effects for
society.Comment: 65 pages, 1 figure, Visioneer White Paper, see
http://www.visioneer.ethz.c
The Leptonic Higgs as a Messenger of Dark Matter
We propose that the leptonic cosmic ray signals seen by PAMELA and ATIC
result from the annihilation or decay of dark matter particles via states of a
leptonic Higgs doublet to leptons, linking cosmic ray signals of dark
matter to LHC signals of the Higgs sector. The states of the leptonic Higgs
doublet are lighter than about 200 GeV, yielding large and
event rates at the LHC. Simple models are
given for the dark matter particle and its interactions with the leptonic
Higgs, for cosmic ray signals arising from both annihilations and decays in the
galactic halo. For the case of annihilations, cosmic photon and neutrino
signals are on the verge of discovery.Comment: 34 pages, 9 figures, minor typos corrected, references adde
Measurement of the Ds lifetime
We report precise measurement of the Ds meson lifetime. The data were taken
by the SELEX experiment (E781) spectrometer using 600 GeV/c Sigma-, pi- and p
beams. The measurement has been done using 918 reconstructed Ds. The lifetime
of the Ds is measured to be 472.5 +- 17.2 +- 6.6 fs, using K*(892)0K+- and phi
pi+- decay modes. The lifetime ratio of Ds to D0 is 1.145+-0.049.Comment: 5 pages, 2 figures submitted to Phys. Lett.
Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-
We observes a signal for the double charm baryon Xi_cc+ in the charged decay
mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ ->
Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment
(E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events
over an expected background estimated by event mixing to be 1.38+/-0.13 events.
The Poisson probability that a background fluctuation can produce the apparent
signal is less than 6.4E-4. The observed mass of this state is
(3518+/-3)MeV/c^2, consistent with the published result. Averaging the two
results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak
decay mode confirms the previous SELEX suggestion that this state is a double
charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+
-> Lambda_c K- pi+) = 0.36+/-0.21.Comment: 11 pages, 6 included eps figures. v2 includes improved statistical
method to determine significance of observation. Submitted to PL
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