3,668 research outputs found
Accurate annotation of SeismoCardioGram exploiting multi-dimensional accelerometry
No full textThis paper presents a methodology to assess heartrelated parameters (such as heart rate and heart rate variability) from SeismoCardioGram (SCG) signals acquired with an Inertial Measurement Unit (IMU). Specific SCG landmarks are detected and identified, including Aortic valve Opening (AO) and Isovolumetric Moment (IM) phases. In order to improve detection accuracy and robustness, information from all 3 accelerometer's axes are combined. Preliminary results are promising, highlighting good overall linearity (r 2 > 0.965) with respect to reference ECG-based (ElectroCardioGram) measurements. By considering all 3 accelerometer axes, performance improves over single-axis approaches. Results suggest the feasibility of accurate, continuous measurements of heart rate and its variability (in restconditions) in AAL scenarios, where such information may effectively complement physical activity and activity intensity data
Milano consolato nell' elettione a questo arciuescouado, e promotione alla sagra porpora dell' eminentissimo Federico Visconti : colla sua solennissima entrata seguita a' 11. genaro 1682 e fontioni antecedenti /
No full textFrontispiece coat of arms of Milan, engraved by Federico Agnelli.Signatures: pi⁴ A-G⁴ H⁴(-H4).Mode of access: Internet.Binding: limp vellum. Author & title written on spine
Accurate Heartbeat Detection on Ballistocardiogram Accelerometric Traces
No full textThis paper presents an automated procedure for acquisition and analysis of BallistoCardioGraphy (BCG) traces. A tri-axial accelerometer and a microcontroller unit are used to record heart-induced recoil forces generated from a lying subject. The problem of BCG J-peak annotation is split into two sub-tasks: candidates extraction, based on a detection signal, and actual annotation, guided by subject-specific search windows. Such procedure is derived from an automatic calibration, which is carried out with no need of concurrent ElectroCardioGram (ECG) or user intervention. The algorithm also implements post-annotation checks for refinement of annotation, which effectively reduces the number of missed J-peaks. The impact of each algorithm phase is analyzed, assessing statistical significance of each step; finally, performance is optimized in a data-driven fashion. Results show that the proposed methodology is able to achieve high sensitivity and precision (the median score is 98.9% and 98.1%, respectively) in J-peak detection. The quality of J-peaks timing annotation is further demonstrated by a very low discrepancy between BCG and ECG HR estimates. Over all population, the standard deviation of such error was found to be approximately 6.56 ms, whereas the Mean Absolute Error just 4.7 ms (i.e. ≈1.18;Ts, where Ts = 4 ms is the sampling period). Such scores, indeed, improve over recent related literature
Fully Automated Annotation of Seismocardiogram for Noninvasive Vital Sign Measurements
No full textThis paper presents a fully automated procedure for acquiring and analyzing seismocardiographic (SCG) traces from an Inertial Measurement Unit (IMU) placed over a subject’s sternum. An automated calibration procedure allows for straightforward adaption to different subjects. Calibration is performed once per subject, exploiting ECG (electrocardiogram) markers; relevant patterns and parameters are automatically extracted and used for successive SCG processing, which does not require concurrent ECG information any longer. Annotation of SCG traces is performed in two steps: in the first one, a suitably engineered signal is derived from SCG and used as coarse heartbeat detector; then, annotation can be performed by comparing the prototype extracted at calibration time with segments of SCG data, near to the detected beats. The proposed methodology is validated by direct comparison with ECG, adopted as gold-standard. In particular, three main metrics are taken into account: sensitivity (i.e. percentage of correctly identified heartbeats, compared to ECG), precision (i.e. impact of false positives on truly detected beats) and R2 (i.e. linearity between beat-to-beat measurements as computed by ECG and SCG). Results show satisfactory performance, more than adequate to continuous, long-term monitoring: overall, approximately 90% of heartbeats are correctly detected, on average, with minimal false positives (≈1%). Linearity between ECG and SCG-computed beat-to-beat intervals is extremely high (R2 > 0.95, on average), indicating good agreement between the two measurement methods. These results suggest SCG can be used as a reliable, contactless measure of heart-related parameters
High-Accuracy, Unsupervised Annotation of Seismocardiogram Traces for Heart Rate Monitoring
No full textThis article presents an unsupervised, automated procedure for the analysis of SeismoCardioGram (SCG) signals. SCG is a measure of chest vibrations, induced by the mechanical activity of the heart, that allows to extract relevant parameters, including Heart Rate (HR) and HR Variability (HRV). An initial self-calibration is performed, solely based on SCG traces, yielding a suitable heartbeat template (personalized for each subject). Then, beat detection and timing annotation are performed in two steps: at first, candidate beats are identified and validated, by means of suitably defined detection signals; then, precise timing annotation is achieved by best aligning such candidate beats to the previously extracted template. The algorithm has been validated on two separate datasets, featuring different acquisition setups: the first one is the publicly available CEBS database, reporting SCG signals from subjects lying in supine position, whereas the second one was acquired using a custom setup, involving sitting subjects. Results show good sensitivity and precision scores (98.5%, 98.6% for the CEBS database, and 99.1%, 97.9% for the Custom one, respectively). Also, comparison with ECG gold-standard is given, showing good agreement between beat-to-beat intervals computed from SCG and the ECG gold-standard: on average, R2 scores of 99.3% and 98.4% are achieved on CEBS and Custom datasets, respectively. Furthermore, a low RMS Error is achieved on the CEBS and Custom dataset, amounting to 4.6 ms and 6.2 ms, respectively (i.e. 2.3 Ts and 3.1 Ts, where Ts is the sampling period): such results well compare to related literature. Validation on two different datasets indicates the robustness of the proposed methodology
An accurate and stable bed-based ballistocardiogram measurement and analysis system
No full textAn experimental BallistoCardioGram (BCG) measurement and analysis system is presented, featuring accelerometers placed between the mattress and bed slats. The system can sample BCG waveforms at 500 Hz and can perform unsupervised BCG heartbeat detection and heartbeat interval measurements. The approach is validated on an experimental dataset consisting in 14 subjects recorded while lying in three different positions: supine, left side and right side. The overall performance is good, comparing to other works in literature. In fact, the average sensitivity and precision across subjects and positions is 98.2% and 98.0%, respectively; similarly, an R2 score of 98.2% was achieved between BCG and reference ECG measurements, while Mean Absolute Error and Root Mean Squared Error are as low as 3.9 ms and 5.6 ms. The presented methodology is shown to be resilient to different sleeping positions, as confirmed by Kruskal-Wallis statistical tests (p≈0.91 for sensitivity, p≈0.73 for precision, p≈0.81 for R2, p≈0.26 for MAE, p≈0.20 for RMSE). Moreover, results are in line and comparable to those already achieved on a different measurement scenario featuring a different bed structure. This further proves the stability of the presented BCG measurement and analysis system
»It contained harbours that pleased me like sonnets«. Kleine Poetik der diegetischen Karte
No full textIn this article, Federico Italiano explores the relationship between literature and cartography. Beginning with Stevenson’s Treasure Island, the author frames the topic through a general theoretical lens on the spatial dimension of literary texts. He then focuses on a specific phenomenon of literary "carticity"—the diegetic presence of the map, that is, the map as an integral element of the narrative structure. Among others, Italiano examines the works of Houellebecq and Cormac McCarthy
CA 19-9 serum levels in patients with end-stage idiopathic pulmonary fibrosis (IPF) and other interstitial lung diseases (ILDs): Correlation with functional decline
No full textIdiopathic pulmonary fibrosis presents a progressive and heterogeneous functional decline. CA 19-9 has been proposed as biomarker to predict disease course, but its role remains unclear. We assessed CA 19-9 levels and clinical data in end-stage ILD patients (48 IPF and 20 non-IPF ILD) evaluated for lung transplant, to correlate these levels with functional decline. Patients were categorized based on their rate of functional decline as slow (n = 20; ΔFVC%pred ≤ 10%/year) or rapid progressors (n = 28; ΔFVC%pred ≥ 10%/year). Nearly half of the entire patients (n = 32; 47%) had CA 19-9 levels ≥37kU/L. CA 19-9 levels in IPF were not different from non-IPF ILD populations, however, the latter group had a median CA 19-9 level above the normal cut-off value of 37 KU/l (60 [17-247] kU/L). Among IPF patients, CA 19-9 was higher in slow than in rapid progressors with a trend toward significance (33vs17kU/L; p = 0.055). In the whole population, CA19-9 levels were inversely related with ΔFVC/year (r = -0.261; p = 0.03), this correlation remained in IPF patients, particularly in rapid progressors (r = -0.51; p = 0.005), but not in non. Moreover, IPF rapid progressors with normal CA 19-9 levels showed the greater ΔFVC/year compared to those with abnormal CA 19-9 (0.95 vs. 0.65 L/year; p = 0.03). In patients with end-stage ILD, CA 19-9 may represent a marker of disease severity, whereas its level is inversely correlated with functional decline, particularly among IPF rapid progressors
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