496 research outputs found
Deriving the respiratory sinus arrhythmia from the heartbeat time series using Empirical Mode Decomposition
Heart rate variability (HRV) is a well-known phenomenon whose characteristics
are of great clinical relevance in pathophysiologic investigations. In
particular, respiration is a powerful modulator of HRV contributing to the
oscillations at highest frequency. Like almost all natural phenomena, HRV is
the result of many nonlinearly interacting processes; therefore any linear
analysis has the potential risk of underestimating, or even missing, a great
amount of information content. Recently the technique of Empirical Mode
Decomposition (EMD) has been proposed as a new tool for the analysis of
nonlinear and nonstationary data. We applied EMD analysis to decompose the
heartbeat intervals series, derived from one electrocardiographic (ECG) signal
of 13 subjects, into their components in order to identify the modes associated
with breathing. After each decomposition the mode showing the highest frequency
and the corresponding respiratory signal were Hilbert transformed and the
instantaneous phases extracted were then compared. The results obtained
indicate a synchronization of order 1:1 between the two series proving the
existence of phase and frequency coupling between the component associated with
breathing and the respiratory signal itself in all subjects.Comment: 12 pages, 6 figures. Will be published on "Chaos, Solitons and
Fractals
Qrs detection based on medical knowledge and cascades of moving average filters
Heartbeat detection is the first step in automatic analysis of the electrocardiogram (ECG). For mobile and wearable devices, the detection process should be both accurate and computationally efficient. In this paper, we present a QRS detection algorithm based on moving average filters, which affords a simple yet robust signal processing technique. The decision logic considers the rhythmic and morphological features of the QRS complex. QRS enhancing is performed with channel-specific moving average cascades selected from a pool of derivative systems we designed. We measured the effectiveness of our algorithm on well-known benchmark databases, reporting F1 scores, sensitivity on abnormal beats and processing time. We also evaluated the performances of other available detectors for a direct comparison with the same criteria. The algorithm we propose achieved satisfying performances on par with or higher than the other QRS detectors. Despite the performances we report are not the highest that have been published so far, our approach to QRS detection enhances computational efficiency while maintaining high accuracy
Fonti documentarie e istituzioni culturali nelle città venete dei decenni centrali dell’Ottocento: archivi e biblioteche municipali
Ricerca dedicata alle pratiche di conservazione e ordinamento della documentazione storica medievale e moderna negli archivi municipali delle cittĂ venete, prima e dopo l'unit
Intervista ad Attilio Bartoli Langeli
Intervista a uno dei maggiori diplomatisti italiani del Novecent
Cognitive modulation of psychophysical, respiratory and autonomic responses to cold pressor test
In healthy subjects with high hypnotisability (highs) under hypnosis, subjectively effective suggestions for analgesia abolish the increases in blood pressure associated with cold pressor test (cpt) by reducing the peripheral vascular resistance. The aim of the present study was to investigate the effects of the suggestions of analgesia on the responses to cpt in healthy highs (n = 22) and in low hypnotisable participants (lows, n = 22) out of hypnosis. Cpt was administered without (CPT) and
with suggestions for analgesia (CPT+AN). Psychophysical (pain intensity, pain threshold, cpt duration (time of immersion) and pain tolerance, defined as the difference between cpt duration and pain threshold), respiratory (amplitude and frequency) and autonomic variables (tonic skin conductance, mean RR interval (RR = 1/heart rate), blood pressure, skin blood flow) were studied. The suggestions for analgesia increased cpt duration and RR in both groups, but decreased pain intensity and enhanced pain threshold only in highs; in both groups they did not modulate systolic blood pressure, tonic skin conductance and skin blood flow; thus, increased parasympathetic activity appears responsible for the heart rate reduction induced by suggestions in both groups. In conclusion, our findings show that suggestions modulate pain experience differentially in highs and lows, and are partially effective also in lows. We hypothesize that the mechanisms responsible for the efficacy of suggestions in healthy lows may be involved also in their efficacy in chronic pain patients with
low hypnotisability
Free electron lifetime achievements in Liquid Argon Imaging TPC
A key feature for the success of the liquid Argon imaging TPC (LAr-TPC)
technology is the industrial purification against electro-negative impurities,
especially Oxygen and Nitrogen remnants, which have to be continuously kept at
an exceptionally low level by filtering and recirculating liquid Argon.
Improved purification techniques have been applied to a 120 liters LAr-TPC test
facility in the INFN-LNL laboratory. Through-going muon tracks have been used
to determine the free electron lifetime in liquid Argon against
electro-negative impurities. The short path length here observed (30 cm) is
compensated by the high accuracy in the observation of the specific ionization
of cosmic ray muons at sea level as a function of the drift distance. A free
electron lifetime of (21.4+7.3-4.3) ms, namely > 15.8 ms at 90 % C.L. has been
observed over several weeks under stable conditions, corresponding to a
residual Oxygen equivalent of about 15 ppt (part per trillion). At 500 V/cm,
the free electron speed is 1.5 m/ms. In a LAr-TPC a free electron lifetime in
excess of 15 ms corresponds for instance to an attenuation of less than 15 %
after a drift path of 5 m, opening the way to the operation of the LAr-TPC with
exceptionally long drift distances.Comment: 15 pages, 10 figures; Accepted for publication in JINS
A local trigger system for the large LAr-TPC detector
A special dedicated double-rebinning algorithm has been successfully developed in order to extract the physical hit signal from the TPC wires. This solution has been implemented on digital boards, allowing to realize a local trigger able to identify even localized low-energy small events
Search for anomalies in the {\nu}e appearance from a {\nu}{\mu} beam
We report an updated result from the ICARUS experiment on the search for
{\nu}{\mu} ->{\nu}e anomalies with the CNGS beam, produced at CERN with an
average energy of 20 GeV and travelling 730 km to the Gran Sasso Laboratory.
The present analysis is based on a total sample of 1995 events of CNGS neutrino
interactions, which corresponds to an almost doubled sample with respect to the
previously published result. Four clear {\nu}e events have been visually
identified over the full sample, compared with an expectation of 6.4 +- 0.9
events from conventional sources. The result is compatible with the absence of
additional anomalous contributions. At 90% and 99% confidence levels the limits
to possible oscillated events are 3.7 and 8.3 respectively. The corresponding
limit to oscillation probability becomes consequently 3.4 x 10-3 and 7.6 x 10-3
respectively. The present result confirms, with an improved sensitivity, the
early result already published by the ICARUS collaboration
Measurement of a large electron lifetime in a liquid argon TPC
An unprecedentedly high value of electron lifetime in a liquid argon TPC, about 21ms, has been measured in a test facility at INFN-LNL. This results opens the way to the future development of TPCs with very long drift distances
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