P. Abreu’s research while affiliated with Instituto Superior Técnico and other places

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Publications (264)


Portuguese National Registry of Interventional Cardiology: Official report of percutaneous coronary angiography and intervention from 2014 to 2023
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February 2025

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18 Reads

Revista Portuguesa de Cardiologia

Rita Calé

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Fig. 1 Map of the observatory: left, surface detector stations (grey dots), position of the fluorescence detector eyes and field of view of the telescopes (squares, dashed lines) along with the footprint at the ground of one of the highest-energy multi-eye events in the released data sample (color scale from green to red reflects the arrival time of the shower
Fig. 2 Screenshot of the main page of the Portal [19], with the links to the five different sections displayed. For more details see [22,23]
Table 2 continued
Fig. 5 Visualization: a screenshot of the 3-dimensional display for the exemplary multi-eye hybrid event id 081847956000 (see text for details)
Fig. 6 Analysis tab: exemplary plots resulting from the Python notebooks provided. Top left panel: energy calibration of the SD energy estimator (S 38 for the SD-1500 array); top right panel: energy spectrum

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The Pierre Auger Observatory open data
  • Article
  • Full-text available

January 2025

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66 Reads

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2 Citations

The European Physical Journal C

The Pierre Auger Collaboration has embraced the concept of open access to their research data since its foundation, with the aim of giving access to the widest possible community. A gradual process of release began as early as 2007 when 1% of the cosmic-ray data was made public, along with 100% of the space-weather information. In February 2021, a portal was released containing 10% of cosmic-ray data collected by the Pierre Auger Observatory from 2004 to 2018, during the first phase of operation of the Observatory. The Open Data Portal includes detailed documentation about the detection and reconstruction procedures, analysis codes that can be easily used and modified and, additionally, visualization tools. Since then, the Portal has been updated and extended. In 2023, a catalog of the highest-energy cosmic-ray events examined in depth has been included. A specific section dedicated to educational use has been developed with the expectation that these data will be explored by a wide and diverse community, including professional and citizen scientists, and used for educational and outreach initiatives. This paper describes the context, the spirit, and the technical implementation of the release of data by the largest cosmic-ray detector ever built and anticipates its future developments.

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Inference of the Mass Composition of Cosmic Rays with Energies from 10 18.5 to 10 20 eV Using the Pierre Auger Observatory and Deep Learning

January 2025

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11 Reads

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10 Citations

Physical Review Letters

We present measurements of the atmospheric depth of the shower maximum X max , inferred for the first time on an event-by-event level using the surface detector of the Pierre Auger Observatory. Using deep learning, we were able to extend measurements of the X max distributions up to energies of 100 EeV ( 10 20 eV ), not yet revealed by current measurements, providing new insights into the mass composition of cosmic rays at extreme energies. Gaining a 10-fold increase in statistics compared to the fluorescence detector data, we find evidence that the rate of change of the average X max with the logarithm of energy features three breaks at 6.5 ± 0.6 ( stat ) ± 1 ( syst ) EeV , 11 ± 2 ( stat ) ± 1 ( syst ) EeV , and 31 ± 5 ( stat ) ± 3 ( syst ) EeV , in the vicinity to the three prominent features (ankle, instep, suppression) of the cosmic-ray flux. The energy evolution of the mean and standard deviation of the measured X max distributions indicates that the mass composition becomes increasingly heavier and purer, thus being incompatible with a large fraction of light nuclei between 50 and 100 EeV. Published by the American Physical Society 2025


Analyzing the economic ramifications of the broad implementation of generic prasugrel

October 2024

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3 Reads

European Heart Journal

Introduction The 2023 European Acute Coronary Syndrome (ACS) guidelines state that prasugrel (PRG) should be considered in preference to ticagrelor (TCG) in patients (pts) who proceed to percutaneous coronary angioplasty (PCI). In Portugal, PRG is less available due to earlier evidence considering pretreatment and contraindications for each drug. PRG (10mg) is currently a generic drug, while TCG is not. We aimed to evaluate the proportion of pts that could be switched from TCG to PRG, and the economic impact of a widespread national adoption. Methods To determine eligibility for generic PRG 10mg, we examined a single center prospective database of consecutive ACS pts undergoing PCI in a full year. Eligibility for TCG and PRG was based on drug specific contraindications, previous stroke for PRG and chronic liver disease (CLD) for TCG, and indication for PRG dose reduction (≤60 kg and ≥75 years). To estimate hospital costs we used the price per pill indicated by the pharmacy (0.98€ TCG, 0.67€ PRG). To obtain post-discharge and NHS savings we used the INFARMED public information. We estimated 3500 PCIs per year on a national level, based on published data. Results A total of 780 pts were included, median age 68±10.4years, 523 (67.1%) were male, 51.9% (n=406) had non-ST elevation ACS. Mean admission time was 8.36 days. Considering PRG and TCG contraindications, 157 pts (20.3%) had a previous history of stroke and 20pts (2.6%) had CLD. 150 pts (19.2%) had PRG dose reduction criteria. Eligible for PRG 10mg and TCG 90mg were 434 pts (57.8% of total PCI pts). Cost per admission would be 33 697.35€ for TCG and 17 617.28€ for PRG. At a national level, hospital costs can be reduced by 16080.07€. Considering the 1-year outpatient setting and a widespread generic PRG 10mg adoption, NHS savings are estimated in 898 323.59€, and patient savings in 401248.25€ (198.38€ per patient). Conclusions ACS pts in real-world scenarios exhibit both eligibility for PRG and TCG. Considering the lower cost, the NHS can potentially save 914 403,66€ (figure 1) annually through the widespread adoption of generic PRG 10mg.


Figure 2 Forest plot for adjusted hazard ratios of 5-year primary outcome (cardiovascular death or non-fatal myocardial infarction). Hazard ratios with 95% confidence interval and P-values of comparisons were estimated with COX proportional hazards models. BP, blood pressure; CHF, congestive heart failure; MI, myocardial infarction; PCI, percutaneous coronary intervention; SMuRF, standard modifiable cardiovascular risk factor
Figure 3 Five-year primary outcomes according to the number of standard modifiable cardiovascular risk factors. Five-year Kaplan-Meier event rate estimates with 95% confidence interval. MACE, major adverse cardiovascular events; MI, myocardial infarction; SMuRF, standard modifiable cardiovascular risk factor
Chronic coronary syndromes without standard modifiable cardiovascular risk factors and outcomes: the CLARIFY registry

May 2024

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280 Reads

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3 Citations

European Heart Journal

Background and Aims It has been reported that patients without standard modifiable cardiovascular (CV) risk factors (SMuRFs—diabetes, dyslipidaemia, hypertension, and smoking) presenting with first myocardial infarction (MI), especially women, have a higher in-hospital mortality than patients with risk factors, and possibly a lower long-term risk provided they survive the post-infarct period. This study aims to explore the long-term outcomes of SMuRF-less patients with stable coronary artery disease (CAD). Methods CLARIFY is an observational cohort of 32 703 outpatients with stable CAD enrolled between 2009 and 2010 in 45 countries. The baseline characteristics and clinical outcomes of patients with and without SMuRFs were compared. The primary outcome was a composite of 5-year CV death or non-fatal MI. Secondary outcomes were 5-year all-cause mortality and major adverse cardiovascular events (MACE—CV death, non-fatal MI, or non-fatal stroke). Results Among 22 132 patients with complete risk factor and outcome information, 977 (4.4%) were SMuRF-less. Age, sex, and time since CAD diagnosis were similar across groups. SMuRF-less patients had a lower 5-year rate of CV death or non-fatal MI (5.43% [95% CI 4.08–7.19] vs. 7.68% [95% CI 7.30–8.08], P = 0.012), all-cause mortality, and MACE. Similar results were found after adjustments. Clinical event rates increased steadily with the number of SMuRFs. The benefit of SMuRF-less status was particularly pronounced in women. Conclusions SMuRF-less patients with stable CAD have a substantial but significantly lower 5-year rate of CV death or non-fatal MI than patients with risk factors. The risk of CV outcomes increases steadily with the number of risk factors.


Ground observations of a space laser for the assessment of its in-orbit performance

February 2024

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220 Reads

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3 Citations

The wind mission Aeolus of the European Space Agency was a groundbreaking achievement for Earth observation. Between 2018 and 2023, the space-borne lidar instrument ALADIN onboard the Aeolus satellite measured atmospheric wind profiles with global coverage, which contributed to improving the accuracy of numerical weather prediction. The precision of the wind observations, however, declined over the course of the mission due to a progressive loss of the atmospheric backscatter signal. The analysis of the root cause was supported by the Pierre Auger Observatory in Argentina whose fluorescence detector registered the ultraviolet laser pulses emitted from the instrument in space, thereby offering an estimation of the laser energy at the exit of the instrument for several days in 2019, 2020, and 2021. The reconstruction of the laser beam not only allowed for an independent assessment of the Aeolus performance, but also helped to improve the accuracy in the determination of the laser beam’s ground track on single pulse level. The results presented in this paper set a precedent for the monitoring of space lasers by ground-based telescopes and open new possibilities for the calibration of cosmic-ray observatories.


FIG. 2. Comparison of X max for showers measured simultaneously by both AERA and the FD. A diagonal line is shown to guide the eye. Shown at the top is the Pearson correlation coefficient r with corresponding p value (the probability to obtain an r of at least that value from uncorrelated data). Shown at the bottom is the distribution (kernel density estimation) of the differences with mean μ and spread σ.
FIG. 3. Resolution of the X max reconstruction method, δ X max , as a function of energy in units of column density. The median values of the uncertainties on X max (circles with uncertainties σ b from bootstrap resampling) for our set of showers are shown per energy bin along with the parametrized fit [Eq. (1)] of the resolution of X max (solid line with 1σ-confidence bands). Also shown are the resolutions achieved by the Auger fluorescence telescopes [29]. The black hatched region at low energy indicates the cut on energy for this AERA analysis. The size of the energy bins with the number of showers per bin is inset at the bottom of the figure.
Demonstrating Agreement between Radio and Fluorescence Measurements of the Depth of Maximum of Extensive Air Showers at the Pierre Auger Observatory

January 2024

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72 Reads

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9 Citations

Physical Review Letters

We show, for the first time, radio measurements of the depth of shower maximum ( X max ) of air showers induced by cosmic rays that are compared to measurements of the established fluorescence method at the same location. Using measurements at the Pierre Auger Observatory we show full compatibility between our radio and the previously published fluorescence dataset, and between a subset of air showers observed simultaneously with both radio and fluorescence techniques, a measurement setup unique to the Pierre Auger Observatory. Furthermore, we show radio X max resolution as a function of energy and demonstrate the ability to make competitive high-resolution X max measurements with even a sparse radio array. With this, we show that the radio technique is capable of cosmic-ray mass composition studies, both at Auger and at other experiments. Published by the American Physical Society 2024


Revascularization of coronary chronic total occlusions in the elderly: what results? - The insights of a multicentre national registry

November 2023

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4 Reads

European Heart Journal

Lately, the remarkable progress in knowledge and treatment of cardiovascular diseases has been significantly impacting society's morbidity and mortality. However, the burden of coronary artery disease (CAD) remains non-negligible. In addition, as a consequence of demographic changes, age, as a non-modifiable cardiovascular risk factor, makes it increasingly important to focus on the elderly. Up to one-fifth of patients with CAD have a chronic total occlusion (CTO) of a coronary artery, defined as a lesion with 100% stenosis and Thrombolysis In Myocardial Infarction (TIMI) flow grade 0 that exists for more than 3 months. There is current evidence that successful CTO-percutaneous coronary intervention (PCI) is associated with clinical benefits. However, elderly patients are currently underrepresented in CTO-PCI randomized controlled trials and registries, and its clinical impact and safety in this group of patients are still debated. This study aims to characterise patients submitted to CTO-PCI and compare the baseline characteristics, coronary intervention features, intraprocedural complications and in-hospital mortality between patients younger and older than 75. The authors performed a retrospective analysis of adult patients submitted to a CTO-PCI, included in the Portuguese Registry on Interventional Cardiology between January 2019 and December 2022. Comparison tests between groups for parametric and non-parametric variables were performed. A p-value less than 0.05 was considered statistically significant. A total of 353 patients who underwent CTO-PCI were analysed, 271 (76.8%) with 18 to 74 years old (group 1) and 82 (23.2%) with 75 or more years old (group 2). Table 1 shows the most important baseline characteristics, with similar features for both groups except body mass index and smoking habits. Table 2 demonstrates the differences between the groups regarding PCI, with the left main and left anterior descending arteries being more treated among older patients and the right coronary artery in younger patients. Complete coronary revascularization and procedure success rate did not differ significantly between groups (p-value=0.19 and p-value=0.59, respectively). Finally, table 3 presents the main intra-procedural and in-hospital complications, with a significant difference only for occlusion of the side branch, occurring in 2 patients aged over 75 years (p-value=0.01). In conclusion, in our registry, the elderly presents a high success rate in the complete recanalization of CTO lesions, comparable to the group under 75 years of age. However, the presence of side branch occlusion was higher in older patients, without other significant differences in intraprocedural and in-hospital complications, including mortality. Further studies including a large sample and follow-up analysis would be essential to better understand the rate of risks related to PCI-CTO potentially associated with the complexity and comorbidities of the elderly.Table 1Table 2 and 3


A Catalog of the Highest-energy Cosmic Rays Recorded during Phase I of Operation of the Pierre Auger Observatory

February 2023

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92 Reads

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13 Citations

The Astrophysical Journal Supplement Series

A catalog containing details of the highest-energy cosmic rays recorded through the detection of extensive air showers at the Pierre Auger Observatory is presented with the aim of opening the data to detailed examination. Descriptions of the 100 showers created by the highest-energy particles recorded between 2004 January 1 and 2020 December 31 are given for cosmic rays that have energies in the range 78-166 EeV. Details are also given on a further nine very energetic events that have been used in the calibration procedure adopted to determine the energy of each primary. A sky plot of the arrival directions of the most energetic particles is shown. No interpretations of the data are offered. © 2023. The Author(s). Published by the American Astronomical Society.


Figure 1 Numbers of new diagnoses of COVID-19 per week and of overall and primary percutaneous coronary interventions performed per week in Portugal, March 1---May 2, 2020. P-PCIs: primary percutaneous coronary interventions; PCIs: percutaneous coronary interventions.
Variation in the number of percutaneous coronary interventions performed for ST-elevation myocardial infarction by geographic region.
Variation in the number of percutaneous coronary interventions for non-ST-elevation acute coronary syndrome by geographic region.
Variation in the number of percutaneous coronary interventions performed for chronic coronary syndromes by geographic region.
Variation in the overall number of percutaneous coronary interventions performed by geographic region.
Impacto da pandemia por COVID-19 nas intervenções coronárias percutâneas em Portugal

August 2022

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87 Reads

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2 Citations

Revista Portuguesa de Cardiologia

Introduction: The COVID-19 pandemic has imposed an unprecedented burden on healthcare systems worldwide, changing the profile of interventional cardiology activity. Objectives: To quantify and compare the number of percutaneous coronary interventions (PCIs) performed for acute and chronic coronary syndromes during the first COVID-19 outbreak with the corresponding period in previous years. Methods: Data on PCI from the prospective multicenter Portuguese Registry on Interventional Cardiology (RNCI) were used to analyze changes in PCI for ST-elevation myocardial infarction (STEMI), non-ST-elevation acute coronary syndromes (NSTE-ACS) and chronic coronary syndromes (CCS). The number of PCIs performed during the initial period of the COVID-19 outbreak in Portugal, from March 1 to May 2, 2020, was compared with the mean frequency of PCIs performed during the corresponding period in the previous three years (2017-2019). Results: The total number of PCIs procedures was significantly decreased during the initial COVID-19 outbreak in Portugal (-36%, p<0.001). The reduction in PCI procedures for STEMI, NSTE-ACS and CCS was, respectively, -25% (p<0.019), -20% (p<0.068) and -59% (p<0.001). Conclusions: Compared with the corresponding period in the previous three years, the number of PCI procedures performed for STEMI and CCS decreased markedly during the first wave of the COVID-19 pandemic in Portugal.


Citations (75)


... The portal offers a user-friendly interface for browsing data, complemented by an immersive 3D animation of events in its Visualization section. The Analysis section includes Python notebooks that explain the main physics analyses published by the Pierre Auger Collaboration, helping users better understand the results [3]. Figure 2 illustrates the reconstruction of the highest-energy hybrid event in the released UHECR catalog [5]. ...

Reference:

Communicating astroparticle physics with the public: the Pierre Auger Observatory experience
The Pierre Auger Observatory open data

The European Physical Journal C

... Mass composition of ultra-high-energy cosmic rays at the Pierre Auger Observatory Thomas Fitoussi elongation rate, possibly linked to spectral features [27]. Both measurements have shown large discrepancy to the QGSJet II-04 predictions for σ X max , suggesting not to use this model for air-shower simulation. ...

Inference of the Mass Composition of Cosmic Rays with Energies from 10 18.5 to 10 20 eV Using the Pierre Auger Observatory and Deep Learning

Physical Review Letters

... However, other nonconventional factors such as exposure to pollutants, social deprivation, occupational stress, hormonal changes, environmental noise, and the area of the world in which we live must also be emphasized. 3 All these phenomena can cause alterations in coronary flow, either by atheroma plaque or by alteration of the microcirculation. For the diagnosis of these diseases, many studies are required, such as electrocardiograms, echocardiograms, cardiac scintigraphy, magnetic resonance imaging, coronary artery tomography, or invasive coronary angiography. ...

Chronic coronary syndromes without standard modifiable cardiovascular risk factors and outcomes: the CLARIFY registry

European Heart Journal

... Next, a likelihood approach is used to 10 18 match the simulations to the measured shower, evaluating and correcting for reconstruction biases and determining the reconstruction uncertainty. The method is described in detail in [9][10][11]. We compare the results to measurements of the FD on an event-by-event basis and find no significant bias and a spread of the measurements compatible with the combined resolutions of the two detectors (see Figure 2, left). ...

Demonstrating Agreement between Radio and Fluorescence Measurements of the Depth of Maximum of Extensive Air Showers at the Pierre Auger Observatory

Physical Review Letters

... It will be important also to scrutinize the excellent agreement between the Auger and TA spectra below 10 19 eV to better understand its implications in the understanding of the FD energy estimation. A new interesting perspective for the comparison of Auger and TA energy scales is through the detection of lasers that will be fired accross the two observatories from the Aeolus satellite [13]. ...

Ground observations of a space laser for the assessment of its in-orbit performance

... Recently, we studied the localization of the "Amaterasu Particle", the highest-energy event detected by the TA collaboration [10], using the UF23 model variations of the coherent Galactic magnetic field to backtrack its arrival direction at the edge of the Galaxy [11]. For this conference we apply the same analysis to the four highest-energy events from the Auger phase I data set [12]. These are listed in Table 2. ...

A Catalog of the Highest-energy Cosmic Rays Recorded during Phase I of Operation of the Pierre Auger Observatory

The Astrophysical Journal Supplement Series

... As more observational instruments have been deployed, the presence of the GZK cutoff has been further validated [48,49,50]. The observation of the GZK cutoff also imposes stringent constraints on LV parameters of protons from theoretical analyses [51,52,53]; for instance, the Pierre Auger Observatory obtains constraints on LV in both the electromagnetic and hadronic sectors by comparing observational data with LV simulations of the energy spectrum, cosmic-ray composition, and upper limits on photon flux [54,55]. Despite this, there remain ultrahigh-energy events that present intriguing possibilities, such as the Telescope Array experiment's detection of an exceptionally energetic particle registered at 2.44 ± 0.29 (stats.) ...

Testing effects of Lorentz invariance violation in the propagation of astroparticles with the Pierre Auger Observatory

... While numerous registries have focused on the clinical outcomes of revascularization guided by coronary physiology [10][11][12][13], its relatively slow uptake in clinical practice in spite of convincing scientific evidence and strong guideline recommendations is not well understood. Data indicate that in clinical practice, pressure indices are only measured occasionally in Germany [14] and elsewhere in the world [15,16]. ...

Adoption and patterns of use of invasive physiological assessment of coronary artery disease in a large cohort of 40 821 real-world procedures over a 12-year period
  • Citing Article
  • October 2021

Revista Portuguesa de Cardiologia (English Edition)

... Furthermore, The Pierre Auger Observatory (PAO) has found a correlation between SBGs and Ultra-High Energy Cosmic Rays (UHECRs) [5]. Indeed, Ref. [6] has studied the possibility for SBGs to power the UHECR spectrum measured by the PAO [7][8][9][10]. As a result, SFGs and SBGs are important tools for studying the CR physics. ...

The energy spectrum of cosmic rays beyond the turn-down around 1017\boldsymbol{10^{17}} eV as measured with the surface detector of the Pierre Auger Observatory

The European Physical Journal C

... Thus, the persistence of the visual estimation approach and the resulting overestimation tendency may arguably be contributing to the seemingly low usage rates (6%-13%) of physiology in cath labs. 10,11,24 Last, the growing relevance of imaging for decisionmaking in the cath lab further adds to this issue, as recently highlighted in a major clinical trial, 25 further points to the importance of avoiding the so-called "oculostenotic reflex." ...

Adoption and patterns of use of invasive physiologicalassessment of coronary artery disease in a large cohortof 40 821 real-world procedures over a 12-year period
  • Citing Article
  • August 2021

Revista Portuguesa de Cardiologia (English Edition)