733 research outputs found

    Analysis of the convergence of the 1/t and Wang-Landau algorithms in the calculation of multidimensional integrals

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    In this communication, the convergence of the 1/t and Wang - Landau algorithms in the calculation of multidimensional numerical integrals is analyzed. Both simulation methods are applied to a wide variety of integrals without restrictions in one, two and higher dimensions. The errors between the exact and the calculated values of the integral are obtained and the efficiency and accuracy of the methods are determined by their dynamical behavior. The comparison between both methods and the simple sampling Monte Carlo method is also reported. It is observed that the time dependence of the errors calculated with 1/t algorithm goes as N^{-1/2} (with N the MC trials) in quantitative agreement with the simple sampling Monte Carlo method. It is also showed that the error for the Wang - Landau algorithm saturates in time evidencing the non-convergence of the methods. The sources for the error are also determined.Comment: 8 pages, 5 figure

    The record of the Paleocene-Eocene thermal maximum in the Ager Basin (Central Pyrenees, Spain)

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    The sedimentary record straddling the Paleocene/Eocene boundary in the Ager Basin (southern Central Pyrenees) was investigated by combining facies analysis, sequence stratigraphy and stable isotope data, within an interval characterized by a great variability of depositional environments. The occurrence of the Paleocene-Eocene Thermal Maximum (PETM) climatic anomaly is tentatively constrained by analogy with its stratigraphic range in the adjacent Tremp-Graus Basin. The main body of the carbon isotope excursion associated with the PETM may be recorded by lacustrine carbonates characterized by a ~ -3‰ shift in d13C with respect to analogous deposits of Thanetian age; a similar shift is recorded between in situ and resedimented pedogenic carbonates, a feature that suggests the partial erosion of the P/E boundary in the Ager Basin

    Are fluid inclusions in gypsum reliable paleoenvironmental indicators? An assessment of the evidence from the Messinian evaporites

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    The paleosalinity of water from which the gypsum precipitated during the Messinian salinity crisis is a controversial issue. Recent microthermometry studies on primary fluid inclusions in gypsum provided very low salinity values not compatible with precipitation from seawater, and suggested strong mixing between seawater and nonmarine waters enriched in calcium sulfate. We applied a new microthermometric protocol on gypsum crystals from nine Mediterranean sections that were experimentally stretched to measure a larger population of fluid inclusions. The results show salinities ranging from 9 to 238 wt‰ NaCl equivalent, largely falling within the evaporation path of normal seawater. The data from previous studies were obtained mostly from those fluid inclusions capable of nucleating a stable bubble after a weak stretching, which probably correspond to those having a lower salinity acquired through post-depositional crack-and-seal processes. Our data suggest instead that the primary gypsum precipitated from a marine brine, later modified by post-trapping processes during tectonics and exhumation

    The Messinian "Calcare di Base" (Sicily, Italy) revisited

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    Three different types of carbonate deposits are included within the "Calcare di Base",commonly envisaged to record the Messinian salinity crisis onset: type 1 consists of sulphur-bearinglimestones, representing the biogenic product of bacterial sulphate reduction after original gypsum;type 2 comprises dm-thick laminated dolomitic limestones interbedded with diatomites, sapropels andmarls found at the top the Tripoli Formation; type 3, the most common variety, consists of m-thickbrecciated limestones interbedded with shales and clastic gypsum.Type 3 shows sedimentary features suggesting a clastic origin and deposition from high- to lowdensitygravity flows; thus, these deposits can be regarded as an end-member of a large variety ofevaporite-bearing gravity flow deposits, with a dominant carbonate component.The genetic and stratigraphic characterization of these carbonates has strong implications for a bettercomprehension of Messinian events; the three types of Calcare di Base seem to have formed duringdifferent stages of the Messinian salinity crisis (MSC). Type 2 formed in the first stage (5.96-5.60 Ma),and is the only type that can be regarded as the Lower Gypsum time-equivalent. Type 3 was depositedin the second stage (5.60-5.55 Ma) and its base is associated with a regional-scale hiatus and erosion(Messinian erosional surface). Type 1 formed even later, likely in post-Messinian time, throughdiagenetic processes affecting resedimented gypsum deposited during the second stage of the MSC.It follows that not all the Calcare di Base deposits record the onset of the Messinian salinity crisis, ascommonly thought. Thus, a detailed facies characterization of these carbonate deposits is fundamental for both stratigraphic reconstructions and a better comprehension of Messinian events

    Pleistocene magnetochronology of early hominin sites at Ceprano and Fontana Ranuccio, Italy

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    Paleomagnetic analyses were conducted on two cores drilled at Ceprano in central Italy where an incomplete hominin cranium was discovered in 1994, as well as on two additional cores from the nearby site of Fontana Ranuccio that yielded hominin remains associated with an Acheulean industry. No evidence for the 0.78 Ma Brunhes–Matuyama boundary was found at Ceprano down to 45 m below the level that yielded the hominin cranium. The Ceprano lithostratigraphy and the paleomagnetic age constraints are broadly consistent with the stratigraphy of the Liri lacustrine sequence of the Latina Valley, constrained by published K–Ar ages between ~ 0.6 and ~ 0.35 Ma, and according to an age model with magnetic susceptibility supported by pollen facies data, suggest that the level that yielded the hominin cranium has an age of ~ 0.45 (+ 0.05, − 0.10) Ma. Evidence for the Brunhes–Matuyama boundary was found at Fontana Ranuccio about 40 m below the hominin level, consistent with a K–Ar age of ~ 0.46 Ma reported for this level. Hence the Ceprano and Fontana Ranuccio hominin occurrences may be of very similar mid-Brunhes age

    Pleistocene magnetochronology of early hominin sites at Ceprano and Fontana Ranuccio, Italy

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    Paleomagnetic analyses were conducted on two cores drilled at Ceprano in central Italy where an incomplete hominin cranium was discovered in 1994, as well as on two additional cores from the nearby site of Fontana Ranuccio that yielded hominin remains associated with an Acheulean industry. No evidence for the 0.78 Ma Brunhes–Matuyama boundary was found at Ceprano down to 45 m below the level that yielded the hominin cranium. The Ceprano lithostratigraphy and the paleomagnetic age constraints are broadly consistent with the stratigraphy of the Liri lacustrine sequence of the Latina Valley, constrained by published K–Ar ages between ~ 0.6 and ~ 0.35 Ma, and according to an age model with magnetic susceptibility supported by pollen facies data, suggest that the level that yielded the hominin cranium has an age of ~ 0.45 (+ 0.05, − 0.10) Ma. Evidence for the Brunhes–Matuyama boundary was found at Fontana Ranuccio about 40 m below the hominin level, consistent with a K–Ar age of ~ 0.46 Ma reported for this level. Hence the Ceprano and Fontana Ranuccio hominin occurrences may be of very similar mid-Brunhes age

    Remarks on the Messinian evaporites of Zakynthos Island (Ionian Sea, Eastern Mediterranean)

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    Detailed mapping of the Neogene deposits on Zakynthos Island shows that the Messinian primary evaporite basins, formed over Ionian basement, are delimited by the westernmost outcrop of the Triassic evaporitic diapirs, located west of the Kalamaki-Argasi Messinian gypsum unit. The post-Miocene external Ionian thrust is emplaced west of the Triassic diapirs. Planktonic foraminifera biostratigraphy indicates that primary evaporite accumulation took place probably during the first stage of the Messinian salinity crisis (5.96-5.60 Ma), in shallower parts of a foreland basin, formed over the Pre-Apulian and the Ionian zone basement. Establishment of these depositional environments, before the Ionian thrust emplacement, was probably due to the particularities of the foreland basin, which extended from the external Ionian to the internal Pre-Apulian zone. Field observations, borehole data and an onshore seismic profile show that the Neogene sediments over the Pre-Apulian basement correspond to the foredeep through forebulge domain of the foreland basin, as it is documented from their spatial thickness distribution. In contrast, the Neogene sediments over the Ionian basement correspond to the wedge top of the foreland basin, which was less subsiding, as it is deduced by their reduced thickness. This lower subsidence rate was the result of the concurrent diapiric movements of the Ionian Triassic evaporites. In Agios Sostis area, located over Pre-Apulian basement, the Neogene sequence is intercalated by decametre-thick resedimented blocks consisting of shallow water selenite. To the southeast, this mass-wasting Messinian gypsum passes to mainly gypsum turbidite. In Kalamaki-Argasi area, located over Ionian basement, the shallow water environment led to the deposition of the observed primary gypsum. Erosion of the primary gypsum of both forebulge and wedge top supplied the foreland basin’s depocenter with gypsum turbidites. Η λεπτομερής χαρτογράφηση των Νεογενών αποθέσεων της Ζακύνθου δείχνει ότι οι λεκάνες πρωτογενούς Μεσσήνιας εβαποριτικής απόθεσης, που σχηματίστηκαν πάνω σε Ιόνιο υπόβαθρο, οριοθετούνται από τη δυτικότερη εμφάνιση των Τριαδικών εβαποριτικών διάπειρων (δυτικά της Μεσσήνιας ενότητας γύψου Καλαμάκι-Αργάσι). Η μετα-Μειοκαινική εξωτερική Ιόνια επώθηση τοποθετείται δυτικά αυτών των Τριαδικών διάπειρων. Βιοστρωματογραφική ανάλυση των συναθροίσεων πλαγκτονικών τρηματοφόρων στα Νεογενή ιζήματα δείχνει ότι η συσσώρευση πρωτογενούς εβαπορίτη έλαβε χώρα πιθανά κατά το πρώτο στάδιο της κρίσης αλμυρότητας του Μεσσηνίου (5.96-5.60 Εκατ.χρ.), στα αβαθέστερα τμήματα της λεκάνης προχώρας, η οποία σχηματίστηκε πάνω στο Προ-Απούλιο και Ιόνιο αλπικό υπόβαθρο. Ο σχηματισμός των περιβαλλόντων ιζηματογένεσης, πριν από την Ιόνια επώθηση, πιθανά οφείλεται στις ιδιαιτερότητες της λεκάνης προχώρας, η οποία εκείνο το διάστημα εκτείνονταν από την εξωτερική Ιόνια ως την εσωτερική Προ-Απούλια ζώνη. Νέα δεδομένα υπαίθρου, σε συνδυασμό με τη βιοστρωματογραφία, τα στοιχεία γεωτρήσεων και μία διαθέσιμη σεισμική τομή δείχνουν ότι τα Νεογενή ιζήματα πάνω στο Προ-Απούλιο υπόβαθρο αντιστοιχούν στον τμήμα της λεκάνης προχώρας, από το προβύθισμα (foredeep) ως την πρόσθια ανύψωση (forebulge), όπως αυτό διαπιστώνεται από την χωρική κατανομή του πάχους τους. Αντίθετα, τα Νεογενή ιζήματα πάνω στο Ιόνιο υπόβαθρο αντιστοιχούν στο τμήμα της λεκάνης προχώρας που βρίσκεται πάνω στο μετωπικό πρίσμα της ορογένεσης (wedge top), το οποίο βυθίζονταν λιγότερο όπως συνάγεται από το ελαττωμένο πάχος των ιζημάτων. Ο μικρότερος ρυθμός βύθισης οφείλεται στις διαπειρικές κινήσεις των Τριαδικών εβαποριτών. Στη Νεογενή ακολουθία, που βρίσκεται πάνω σε Προ-Απούλιο υπόβαθρο (περιοχή Άγιος Σώστης), παρεμβάλλονται επανιζηματοποιημένα μπλοκ δεκαμετρικού πάχους αποτελούμενα από σεληνίτη μικρού βάθους απόθεσης. Προς νότο, αυτή η βαρυτικά μεταφερόμενη μάζα της Μεσσήνιας γύψου μεταπίπτει κυρίως σε τουρβιδιτική γύψο. Στην περιοχή Καλαμάκι-Αργάσι που βρίσκεται πάνω σε Ιόνιο υπόβαθρο, το αβαθές περιβάλλον οδήγησε στην απόθεση της παρατηρούμενης πρωτογενούς γύψου. Η διάβρωση της πρωτογενούς γύψου τόσο της πρόσθιας ανύψωσης όσο και του μετωπικού πρίσματος επώθησης τροφοδότησαν το προβύθισμα της λεκάνης προχώρας με τουρβιδίτες γύψου

    Exploring the interplay between metabolic power and equivalent distance in training games and official matches in soccer: a machine learning approach.

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    Introduction: This study aimed to explore the interplay between metabolic power (MP) and equivalent distance (ED) and their respective roles in training games (TGs) and official soccer matches. Furthermore, the secondary objective was to investigate the connection between external training load (ETL), determined by the interplay of metabolic power and equivalent distance, and internal training load (ITL) assessed through HR-based methods, serving as a measure of criterion validity. Methods: Twenty-one elite professional male soccer players participated in the study. Players were monitored during 11 months of full training and overall official matches. The study used a dataset of 4269 training games and 380 official matches split into training and test sets. In terms of machine learning methods, the study applied several techniques, including K-Nearest Neighbors, Decision Tree, Random Forest, and Support-Vector Machine classifiers. The dataset was divided into two subsets: a training set used for model training and a test set used for evaluation. Results: Based on metabolic power and equivalent distance, the study successfully employed four machine learning methods to accurately distinguish between the two types of soccer activities: TGs and official matches. The area under the curve (AUC) values ranged from 0.90 to 0.96, demonstrating high discriminatory power, with accuracy levels ranging from 0.89 to 0.98. Furthermore, the significant correlations observed between Edwards' training load (TL) and TL calculated from metabolic power metrics confirm the validity of these variables in assessing external training load in soccer. The correlation coefficients (r values) ranged from 0.59 to 0.87, all reaching statistical significance at p < 0.001. Discussion: These results underscore the critical importance of investigating the interaction between metabolic power and equivalent distance in soccer. While the overall intensity may appear similar between TGs and official matches, it is evident that underlying factors contributing to this intensity differ significantly. This highlights the necessity for more comprehensive analyses of the specific elements influencing physical effort during these activities. By addressing this fundamental aspect, this study contributes valuable insights to the field of sports science, aiding in the development of tailored training programs and strategies that can optimize player performance and reduce the risk of injuries in elite soccer
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