971 research outputs found
Exploring Margin Maximization for Biometric Score Fusion
No full textBiometric systems are automated methods based on physical or behavioral characteristics of an individual for determining her/his identity. An important aspect of these systems is the reliability against forgery that is surely improved when using multiple sources of biometric information. In such cases combination rules can be applied to fuse the different scores thus obtaining a multibiometric system.
In this paper we analyze a method based on margin maximization for building a linear combination of biometric scores. The margin is a central concept in machine learning research and several theoretical results exist which show that improving the margin on the training set is beneficial for the generalization error of an ensemble of classifiers. Experiments performed on real biometric data and comparisons with other commonly employed fusion rules show that a combination based on margin maximization is particularly effective with respect to other established fusion methods
Relative Efficacy of Sacubitril-Valsartan, Vericiguat, and SGLT2 Inhibitors in Heart Failure with Reduced Ejection Fraction: a Systematic Review and Network Meta-Analysis
No full textBackground: Sacubitril/valsartan, vericiguat, and the sodium-glucose co-transporter-2 inhibitors (SGLT2i) dapagliflozin and empagliflozin proved effective in phase 3 trials on heart failure with reduced ejection fraction (HFrEF). Methods: We compared the treatment arms (sacubitril/valsartan, vericiguat, and SGLT2i) with the respective control arms (standard-of-care [SOC]) through a network meta-analysis of the phase 3 trials (PARADIGM-HF, VICTORIA, DAPA-HF, EMPEROR-Reduced), a phase 2 trial on vericiguat and the HFrEF subgroup of DECLARE-TIMI 58. Results: There was a trend towards decreased risk of cardiovascular (CV) death or HF hospitalization with SGLT2i than sacubitril/valsartan (HR 0.92, 95% CI 0.81 to 1.05) and vericiguat (HR 0.83, 95% CI 0.73 to 0.94). A non-significant effect of SGLT2i on CV mortality compared to sacubitril/valsartan (HR 1.04, 95% CI 0.88 to 1.24) and vericiguat (HR 0.88, 95% CI 0.63 to 1.22) was found. SGLT2i demonstrated the greatest effect on HF hospitalization (HR 0.69, 95% CI 0.62 to 0.77) over the SOC, as well as a significant benefit over vericiguat (HR 0.77, 95% CI 0.66 to 0.89), but not over sacubitril/valsartan (HR 0.87, 95% CI 0.75 to 1.02). SGLT2i were ranked as the most effective therapy, followed by sacubitril/valsartan and vericiguat. Conclusions: Based on an indirect comparison, SGLT2i therapy is not associated with a significantly lower risk of CV death or HF hospitalization or CV death alone compared to sacubitril/valsartan or vericiguat. The risk of HF hospitalization does not differ significantly between patients on SGLT2i or sacubitril/valsartan, while dapagliflozin is superior to vericiguat. Registration Number: PROSPERO ID 186351
Redefining the epidemiology of cardiac amyloidosis. A systematic review and meta-analysis of screening studies
No full textAims: An algorithm for non-invasive diagnosis of amyloid transthyretin cardiac amyloidosis (ATTR-CA) and novel disease-modifying therapies have prompted an active search for CA. We examined the prevalence of CA in different settings based on literature data. Methods and results: We performed a systematic search for screening studies on CA, focusing on the prevalence, sex and age distribution in different clinical settings. The prevalence of CA in different settings was as follows: bone scintigraphy for non-cardiac reasons (n = 5 studies), 1% (95% confidence interval [CI] 0%–1%); heart failure with preserved ejection fraction (n = 6), 12% (95% CI 6%–20%); heart failure with reduced or mildly reduced ejection fraction (n = 2), 10% (95% CI 6%–15%); conduction disorders warranting pacemaker implantation (n = 1), 2% (95% CI 0%–4%); surgery for carpal tunnel syndrome (n = 3), 7% (95% CI 5%–10%); hypertrophic cardiomyopathy phenotype (n = 2), 7% (95% CI 5%–9%); severe aortic stenosis (n = 7), 8% (95% CI 5%–13%); autopsy series of ‘unselected’ elderly individuals (n = 4), 21% (95% CI 7%–39%). The average age of CA patients in the different settings ranged from 74 to 90 years, and the percentage of men from 50% to 100%. Many patients had ATTR-CA, but the average percentage of patients with amyloid light-chain (AL) CA was up to 18%. Conclusions: Searching for CA in specific settings allows to identify a relatively high number of cases who may be eligible for treatment if the diagnosis is unequivocal. ATTR-CA accounts for many cases of CA across the different settings, but AL-CA is not infrequent. Median age at diagnosis falls in the eighth or ninth decades, and many patients diagnosed with CA are women
The Complex Relationship Between Serum Uric Acid, Endothelial Function and Small Vessel Remodeling in Humans
No full textAims: The relationship between serum uric acid (SUA) and microvascular remodeling in humans remains largely unexplored. We assessed whether SUA provides additional information on the severity of microvascular remodeling than that obtained from the European Heart Score (HS), the patterns of microvascular remodeling associated with changes in SUA levels and the mediation by endothelial function and nitric oxide (NO) availability on this relationship.
Methods: A total of 162 patients included in the microvascular dataset of the Italian Society of Hypertension with available information on SUA, media-to-lumen (M/L) ratio, media cross-sectional area (MCSA), endothelial function, NO availability and HS were included in the analysis. The top tertile of M/L ratio and MCSA were used to define severe microvascular remodeling.
Results: A U-shaped association was observed between SUA and both M/L ratio and MCSA. Adjustment for HS did not affect these associations. SUA was able to reclassify a significant number of subjects without, and with, severe M/L ratio and MCSA remodeling over the HS alone. The microvascular remodeling associated with SUA levels presented a predominant hypertrophic pattern. SUA was inversely associated with endothelial function and NO availability. Structural equation modeling analysis controlling for the HS suggested that the association of SUA with M/L ratio and MCSA was mediated through changes in endothelial function and NO availability.
Conclusions: The addition of SUA to the HS improves the identification of subjects with greater microvascular remodeling. The relationship between SUA and microvascular remodeling is mediated by endothelial function and NO availability
Targeting Cyclic Guanosine Monophosphate to Treat Heart Failure: JACC Review Topic of the Week
No full textThe significant morbidity and mortality associated with heart failure with reduced ejection fraction (HFrEF) or heart failure with preserved ejection fraction (HFpEF) justify the search for novel therapeutic agents. Reduced cyclic guanosine monophosphate levels contribute to HF progression. Among molecules modulating the nitric oxide (NO)–GMP–phosphodiesterase (PDE) pathway, the evaluation of nitrates, synthetic natriuretic peptides (NP), and NP analogs has yielded mixed results. Conversely, sacubitril/valsartan, combining NP degradation inhibition through neprilysin and angiotensin receptor blockade, has led to groundbreaking findings in HFrEF. Other strategies to increase tissue cyclic guanosine monophosphate have been attempted, such as PDE-3 or PDE-5 inhibition (with negative or neutral results), NO-independent soluble guanylate cyclase (sGC) activation, or enhancement of sGC sensitivity to endogenous NO. Following the positive results of the phase 3 VICTORIA (A Study of Vericiguat in Participants With Heart Failure With Reduced Ejection Fraction) trial on the sGC stimulator vericiguat in HFrEF, the main open questions are the efficacy of the sacubitril/valsartan-vericiguat combination in HFrEF and of vericiguat in HFpEF
Massive hadron pair production by 800-GeV/c protons on nuclear targets.
No full textWe report data on proton-nucleon collisions obtained on Fermilab experiment E711, in which high transverse momentum hadrons are produced near 90° in the proton-nucleon center of mass forming high mass states, using an 800 GeV/c proton beam on targets of beryllium, aluminum, iron, and tungsten. The data presented cover the mass range from 7 to 15 GeV/c2, the three dihadron charge states ++, +-, and --, and parton-parton scattering angles up to cosθ*=0.50. We present the differential mass dihadron cross section, as well as the angular and charge dependence of the measurement. The cross section as a function of the parton-parton scattering angle for the three charge states is shown to vary linearly with the value of the atomic weight. While the angular distributions are shown to be independent of the target type, a small dependence on the charge state of the distributions is observed. The data are shown to be in good agreement with extrapolations from previous measurements and phenomenological QCD calculations
A Fuzzy Gap Statistic For Fuzzy C-Means
No full textThe gap statistic is a statistical method for determining the number of optimal clusters for an unsupervised clustering algorithm and has been shown to outperform other cluster validity indices for the K-means clustering algorithm. In this paper, we assess the performance of the gap statistic when applied to the Fuzzy C-Means (FCM) algorithm and introduce a fuzzy gap statistic. We compare the gap statistic performance versus the partition coefficient and entropy indices introduced by Bezdek, the Xie-Beni and extended Xie-Beni indices, and the Fukuyama-Sugeno index. We show that the fuzzy gap statistic is more robust than the ordinary gap statistic for the IRIS data set, and we show promising results when comparing the gap statistic to the traditional fuzzy clustering indices
Performance Evaluation Of Frequency Hopped Receiver Oriented Spread Spectrum Packet Radio Networks
No full textThe author examines the multiple-access capability of frequency-hopped, receiver-oriented, spread-spectrum packet radio networks. The most important indicator of the multiple-access capability of a spread-spectrum packet radio network is the induced packet error probability. The interdependence of byte errors of the desired transmission (i.e., packet) due to the multiple access interference caused by other packets, is determined. An exact method and two approximation methods for the computation of the packet error probability are proposed. The results indicate that the byte errors exhibit a Markovian structure
Packet Error Probabilities In Direct Sequence Spread Spectrum Packet Radio Networks With Bch Codes
No full textThe author computes an upper bound on the packet error probability induced in direct-sequence spread-spectrum networks, when BCH codes are used for the encoding of the packets. The bound, which is introduced here, is valid independently of whether signals arrive with equal or unequal powers at the receiver site. Furthermore, it has a simple form and is easy to compute. In addition, it is valid for other classes of forward error correction codes (e.g., convolutional codes). However, numerical results are presented for BCH codes only
A Fast Approach to Improve Classification Performance of ECOC Classification Systems
No full textError correcting output coding is a well known technique to decompose a multi-class classification problem into a group of two-class problems which can be faced by using a combination of binary classifiers. Each of them is trained on a different dichotomy of the classes. The way the set of classes is mapped on this set of dichotomies may essentially influence the obtained performance. In this paper we present a new tool, the k-NN lookup table to optimize this mapping in a fast way and a fast procedure to change the dichotomies in a proper way. Experiments on artificial and public data sets show that the proposed procedure may significantly improve the ECOC performance in multi-class problems
- …
