| 11. |
- Munini, R., et al.
(author)
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Evidence of Energy and Charge Sign Dependence of the Recovery Time for the 2006 December Forbush Event Measured by the PAMELA Experiment
- 2018
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In: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 853:1
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Journal article (peer-reviewed)abstract
- New results on the short-term galactic cosmic-ray (GCR) intensity variation (Forbish decrease) in 2006 December measured by the PAMELA instrument are presented. Forbush decreases are sudden suppressions of the GCR intensities, which are associated with the passage of interplanetary transients such as shocks and interplanetary coronal mass ejections (ICMEs). Most of the past measurements of this phenomenon were carried out with groundbased detectors such as neutron monitors or muon telescopes. These techniques allow only the indirect detection of the overall GCR intensity over an integrated energy range. For the first time, thanks to the unique features of the PAMELA magnetic spectrometer, the Forbush decrease, commencing on 2006 December 14 and following a CME at the Sun on 2006 December 13, was studied in a wide rigidity range (0.4-20 GV) and for different species of GCRs detected directly in space. The daily averaged GCR proton intensity was used to investigate the rigidity dependence of the amplitude and the recovery time of the Forbush decrease. Additionally, for the first time, the temporal variations in the helium and electron intensities during a Forbush decrease were studied. Interestingly, the temporal evolutions of the helium and proton intensities during the Forbush decrease were found to be in good agreement, while the low rigidity electrons (<2 GV) displayed a faster recovery. This difference in the electron recovery is interpreted as a charge sign dependence introduced by drift motions experienced by the GCRs during their propagation through the heliosphere.
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| 12. |
- Munini, R., et al.
(author)
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Solar modulation of galactic cosmic ray electrons and positrons over the 23rd solar minimum with the PAMELA experiment
- 2015
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In: Proceedings of Science. - : Proceedings of Science (PoS).
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Conference paper (peer-reviewed)abstract
- The satellite-borne PAMELA experiment has been continuously collecting data since 15th June 2006, when it was launched from the Baikonur cosmodrome to detect the charged component of cosmic rays over a wide energy range and with unprecedented statistics. The apparatus design is particularly suited for particle and antiparticle identification. The PAMELA experiment has measured the time variation of electron and positron spectrum at Earth in great detail, extending the measurement down to 70 MeV and 200 MeV respectively. The spectra have been evaluated with data collected from July 2006 to December 2009, i.e. during the A<0 solar minimum of solar cycle 23, over six-months intervals. These spectra provide important information for the study of CR propagation inside the heliosphere and the investigation of the charge-dependent solar modulation.
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| 13. |
- Munini, R., et al.
(author)
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Solar modulation of GCR electrons over the 23rd solar minimum with PAMELA
- 2015
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In: 24TH EUROPEAN COSMIC RAY SYMPOSIUM (ECRS). - : IOP Publishing.
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Conference paper (peer-reviewed)abstract
- The satellite-borne PAMELA experiment has been continuously collecting data since 15th June 2006, when it was launched from the Baikonur cosmodrome to detect the charged component of cosmic rays over a wide energy range and with unprecedented statistics. The apparatus design is particularly suited for particle and antiparticle identification. The PAMELA experiment has measured the electron spectrum at Earth in great detail, extending up to about 100 GeV and down to about 200 MeV. The galactic cosmic ray electron spectra for 2007 and 2009, i.e. measured during the A<0 solar minimum of solar cycle 23, are presented. These fluxes provide important information for the study of charge dependent solar modulation effects.
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| 14. |
- Munini, R., et al.
(author)
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Ten years of positron and electron solar modulation measured by the PAMELA experiment
- 2017
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In: Proceedings of Science. - : Sissa Medialab Srl.
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Conference paper (peer-reviewed)abstract
- The satellite-borne PAMELA experiment was launched on the 15th June 2006 from the Baikonur cosmodrome. Till January 2016 PAMELA has detected the charged component of cosmic-rays (CRs) over a wide energy range. Due to its long flight duration PAMELA represents an ideal detector for cosmic-ray solar modulation studies. Moreover, the capability to measure particles of the same mass with opposite charge allows to investigate the charge-sign dependent solar modulation. The results on the positron and electron intensity variation at Earth over the 23rd solar minimum (July 2006 - January 2009) till the middle of the 24rd solar maximum (December 2015), will be presented. The positron to electron ratio shows a clear time variation interpreted as solar modulation sign-charge dependence introduced by particle drifts. The effect of the polarity reversal of the heliospheric magnetic field, which took place between 2013 and 2014, is also distinctly visible from the PAMELA data. These results provide the first clear indication of how drift effects unfold with time during different phases of the solar activity and their dependence on the particle rigidity and the cyclic polarity of the solar magnetic field.
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| 15. |
- Vannuccini, E., et al.
(author)
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Measurement of Lithium and Beryllium cosmic-ray abundances by the PAMELA experiment
- 2015
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In: Proceedings of Science. - : Proceedings of Science (PoS).
-
Conference paper (peer-reviewed)abstract
- The PAMELA experiment is collecting particles along a low Earth semi-polar orbit on board of Resurs-DK1 satellite since June 2006. The combined information of a silicon tracking system and a scintillator hodoscope provides redundant light-element identification capabilities, via multiple ionization energy-loss measurements. The instrument design is not optimized for nuclei detection, whose high ionization signal progressively saturates the detectors. However, Li and Be nuclei can still be identified by using the full set of information, which allows to efficiently select the two elements against the background of more abundant elements. The main issues of the analysis aiming to optimize the Li and Be selection are discussed in this paper. Preliminary results on the elemental abundances will be presented at the conference.
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| 16. |
- Martucci, M., et al.
(author)
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Proton Fluxes Measured by the PAMELA Experiment from the Minimum to the Maximum Solar Activity for Solar Cycle 24
- 2018
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In: Astrophysical Journal Letters. - : Institute of Physics Publishing (IOPP). - 2041-8205 .- 2041-8213. ; 854:1
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Journal article (peer-reviewed)abstract
- Precise measurements of the time-dependent intensity of the low-energy (<50 GeV) galactic cosmic rays (GCRs) are fundamental to test and improve the models that describe their propagation inside the heliosphere. In particular, data spanning different solar activity periods, i.e., from minimum to maximum, are needed to achieve comprehensive understanding of such physical phenomena. The minimum phase between solar cycles 23 and 24 was peculiarly long, extending up to the beginning of 2010 and followed by the maximum phase, reached during early 2014. In this Letter, we present proton differential spectra measured from 2010 January to 2014 February by the PAMELA experiment. For the first time the GCR proton intensity was studied over a wide energy range (0.08-50 GeV) by a single apparatus from a minimum to a maximum period of solar activity. The large statistics allowed the time variation to be investigated on a nearly monthly basis. Data were compared and interpreted in the context of a state-of-the-art three-dimensional model describing the GCRs propagation through the heliosphere.
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| 17. |
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| 18. |
- Clarke, Robert, et al.
(author)
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Lowering blood homocysteine with folic acid based supplements : Meta-analysis of randomised trials
- 1998
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In: British Medical Journal. - : BMJ. - 0959-8146. ; 316:7135, s. 894-898
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Research review (peer-reviewed)abstract
- Objective: To determine the size of reduction in homocysteine concentrations produced by dietary supplementation with folic acid and with vitamins B-12 or B-6. Design: Meta-analysis of randomised controlled trials that assessed the effects of folic acid based supplements on blood homocysteine concentration. Multivariate regression analysis was used to determine the effects on homocysteine concentrations of different doses of folic acid and of the addition of vitamin B-12 or B-6. Subjects: Individual data on 1114 people included in 12 trials. Findings: The proportional and absolute reductions in blood homocysteine produced by folic acid supplements were greater at higher pretreatment blood homocysteine concentrations (P < 0.001) and at lower pretreatment blood folate concentrations (P < 0.001). After standardisation to pretreatment blood concentrations of homocysteine of 12 μmol/l and of folate of 12 nmol/l (approximate average concentrations for Western populations), dietary folic acid reduced blood homocysteine concentrations by 25% (95% confidence interval 23% to 28%; P < 0.001), with similar effects in the range of 0.5-5 mg folic acid daily. Vitamin B-12 (mean 0.5 mg daily) produced an additional 7% (3% to 10%) reduction in blood homocysteine. Vitamin B-6 (mean 16.5 mg daily) did not have a significant additional effect. Conclusions: Typically in Western populations, daily supplementation with both 0.5-5 mg folic acid and about 0.5 mg vitamin B-12 would be expected to reduce blood homocysteine concentrations by about a quarter to a third (for example, from about 12 μmol/l to 8-9 μmol/l). Large scale randomised trials of such regimens in high risk populations are now needed to determine whether lowering blood homocysteine concentrations reduces the risk of vascular disease.
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| 19. |
- Knot, J, et al.
(author)
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How to set up an effective national primary angioplasty network : Lessons learned from five European countries
- 2009
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In: EuroIntervention. - 1774-024X. ; 3:299, s. 301-309
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Journal article (peer-reviewed)abstract
- AIMS: Percutaneous coronary interventions (PCI) are used to treat acute and chronic forms of coronary artery disease. While in chronic forms the main goal of PCI is to improve the quality of life, in acute coronary syndromes (ACS) timely PCI is a life-saving procedure - especially in the setting of ST-elevation myocardial infarction (STEMI). The aim of this study was to describe the experience of countries with successful nationwide implementation of PCI in STEMI, and to provide general recommendations for other countries. METHODS AND RESULTS: The European Association of Percutaneous Cardiovascular Interventions (EAPCI) recenty launched the Stent For Life Initiative (SFLI). The initial phase of this pan-European project was focused on the positive experience of five countries to provide the best practice examples. The Netherlands, the Czech Republic, Sweden, Denmark and Austria were visited and the logistics of ACS treatment was studied. Public campaigns improved patient access to acute PCI. Regional networks involving emergency medical services (EMS), non-PCI hospitals and PCI centres are useful in providing access to acute PCI for most patients. Direct transfer from the first medical contact site to the cathlab is essential to minimise the time delays. Cathlab staff work is organised to provide acute PCI services 24 hours a day / seven days a week (24/7). Even in those regions where thrombolysis is still used due to long transfer distances to PCI, patients should still be transferred to a PCI centre (after thrombolysis). The highest risk non-ST elevation acute myocardial infarction patients should undergo emergency coronary angiography within two hours of hospital admission, i.e. similar to STEMI patients. CONCLUSIONS: Three realistic goals for other countries were defined based on these experiences: 1) primary PCI should be used for >70% of all STEMI patients, 2) primary PCI rates should reach >600 per million inhabitants per year and 3) existing PCI centres should treat all their STEMI patients by primary PCI, i.e. should offer a 24/7 service
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| 20. |
- Potgieter, Danielle, et al.
(author)
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N-terminal pro-B-type Natriuretic Peptides Prognostic Utility Is Overestimated in Meta-analyses Using Study-specific Optimal Diagnostic Thresholds
- 2015
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In: Anesthesiology. - : LIPPINCOTT WILLIAMS and WILKINS. - 0003-3022 .- 1528-1175. ; 123:2, s. 264-271
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Journal article (peer-reviewed)abstract
- Background:N-terminal fragment B-type natriuretic peptide (NT-proBNP) prognostic utility is commonly determined post hoc by identifying a single optimal discrimination threshold tailored to the individual study population. The authors aimed to determine how using these study-specific post hoc thresholds impacts meta-analysis results. Methods: The authors conducted a systematic review of studies reporting the ability of preoperative NT-proBNP measurements to predict the composite outcome of all-cause mortality and nonfatal myocardial infarction at 30 days after noncardiac surgery. Individual patient-level data NT-proBNP thresholds were determined using two different methodologies. First, a single combined NT-proBNP threshold was determined for the entire cohort of patients, and a meta-analysis conducted using this single threshold. Second, study-specific thresholds were determined for each individual study, with meta-analysis being conducted using these study-specific thresholds. Results: The authors obtained individual patient data from 14 studies (n = 2,196). Using a single NT-proBNP cohort threshold, the odds ratio (OR) associated with an increased NT-proBNP measurement was 3.43 (95% CI, 2.08 to 5.64). Using individual study-specific thresholds, the OR associated with an increased NT-proBNP measurement was 6.45 (95% CI, 3.98 to 10.46). In smaller studies (less than100 patients) a single cohort threshold was associated with an OR of 5.4 (95% CI, 2.27 to 12.84) as compared with an OR of 14.38 (95% CI, 6.08 to 34.01) for study-specific thresholds. Conclusions:Post hoc identification of study-specific prognostic biomarker thresholds artificially maximizes biomarker predictive power, resulting in an amplification or overestimation during meta-analysis of these results. This effect is accentuated in small studies.
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