Search results for " ROC"

Population dynamics and tolerance to desiccation in a crustacean ostracod adapted to life in small ephemeral water bodies

2011

AbstractGiven their small size, isolation and unpredictability, temporary rockpools present high environmental stress and impoverished communities of species that have adapted to such stressful conditions. Special adaptations of the invertebrates living in these habitats include tolerance to desiccation and fast ontogenetic development in order to maintain stable populations and face high risk of extinction. Dozens of small rockpools (mostly with Ø<1m) can be found in east Spain on limestone substrate, where the only known Iberian populations of Heterocypris bosniaca Petkovski et al. (2000), an ostracod species with geographic parthenogenesis, have been recently found. In this survey, two o…

Ancient xenocrystic zircon in young volcanic rocks of the southern Lesser Antilles island arc

2017

Abstract The Lesser Antilles arc is one of the best global examples in which to examine the effects of the involvement of subducted sediment and crustal assimilation in the generation of arc crust. Most of the zircon recovered in our study of igneous and volcaniclastic rocks from Grenada and Carriacou (part of the Grenadines chain) is younger than 2 Ma. Within some late Paleogene to Neogene (~ 34–0.2 Ma) lavas and volcaniclastic sediments however, there are Paleozoic to Paleoarchean (~ 250–3469 Ma) xenocrysts, and Late Jurassic to Precambrian zircon (~ 158–2667 Ma) are found in beach and river sands. The trace element characteristics of zircon clearly differentiate between different types o…

Džeknaifa empīriskās ticamības metodes izmantošana ticamības intervālu konstruēšanai laukumam zem ROC līknes

2015

Mūsdienās arvien lielāku popularitāti gūst neparametriskās statistikas metodes. Viena no šādām plaši izmantotajām metodēm ir empīriskās ticamības metode (EL). To kombinējot ar džeknaifa pseido vērtībām, iegūst džeknaifa empīrisko ticamības metodi (JEL). Šī darba mērķis ir pētīt JEL metodes izmantošanas iespējas normalizēto parciālo laukumu zem ROC līknes (AUC) novērtēšanā. Izmantojot šo metodi, tika konstruēti ticamības intervāli gan vienam normalizētajam parciālajam AUC, gan laukumu starpībai. Darba gaitā tika veiktas arī simulācijas, kas parādīja, ka džeknaifa empīriskās ticamības metode strādā ievērojami labāk par normālās aproksimācijas metodi, kā arī tika apskatīts metodes pielietojums…

Interés de los índices clínicos en el tratamiento quirúrgico de la enterocolitis necrotizante

2015

INTRODUCCIÓN: Uno de los retos fundamentales de la terapia quirúrgica de los neonatos con enterocolitis necrotizante es decidir el momento adecuado para la intervención. Los índices clínicos pueden mejorar el proceso de toma de decisiones en beneficio del paciente: el MDAS (Metabolic Derangement Acuity Score) y el SNAPPE-II (Score for Neonatal Acute Physiology Perinatal Extension-II) son dos índices clínicos que fueron propuestos como buenas pruebas para decir qué pacientes con enterocolitis necrotizante necesitaban tratamiento quirúrgico; no obstante, su rendimiento diagnóstico como predictores de dicho tratamiento quirúrgico no fue calculado. El objetivo de esta investigación fue obtener …

MAJOR AND TRACE ELEMENTS GEOCHEMISTRY IN THE GROUND WATERS OF A VOLCANIC AREA: MOUNT ETNA (SICILY, ITALY)

1998

Thirty-five ground-water samples have been collected from wells, springs and drainage galleries on Mt Etna volcano for the determination of major, minor and trace elements in solution. Attention has been focused in particular on dissolved minor and trace elements, for most of which no data were available in the studied area. In general, dissolution of solids into Etna's ground waters follows from strong interaction between water of meteoric origin, CO2 gas of magmatic origin and the volcanic rocks of the aquifers. However, the R-mode analysis allowed to distinguish several sources of solutes: Al, Co, Ni, Fe, Si, As would derive mainly from alteration of the volcanic rocks of Etna; SO4=, K, …

Source Mechanisms of Laboratory Earthquakes During Fault Nucleation and Formation

2021

Identifying deformation and pre-failure mechanisms preceding faulting is key for fault mechanics and for interpreting precursors to fault rupture. This study presents the results of a new and robust derivation of first motion polarity focal mechanism solutions (FMS) applied to acoustic emission (AE). FMS are solved using a least squares minimization of the fit between projected polarity measurements and the deviatoric stress field induced by dilatational (T-type), shearing (S-type), and compressional (C-type) sources. 4 × 10 cm cylindrical samples of Alzo Granite (AG, porosity &lt;1%) and Darley Dale Sandstone (DDS, porosity ≈14%) underwent conventional triaxial tests in order to investigat…

Systematics and phylogeography of the genus Tigriopus (Copepoda, Harpacticoida, Harpacticidae) in the basin of the Mediterranean Sea

2020

[ES] El género de copépodos Tigriopus Norman, 1869 se distribuye en todo el mundo en piscinas costeras de rocas y actualmente se considera que incluye 15 especies válidas. Tigriopus fulvus (Fischer, 1860), con su subespecie Tigriopus fulvus adriaticus Van Douwe 1913 y Tigriopus fulvus algiricus Monard 1935, actualmente se informa que ocurren en el área mediterránea, pero actualmente se desconoce la diversidad real del género. Nuestro objetivo fue evaluar la identidad real de las poblaciones mediterráneas de Tigriopus y dilucidar su taxonomía y patrón de diversidad genética. Para alcanzar estos objetivos, utilizamos dos enfoques diferentes. El primero, basado en la morfología, donde las posi…

On the formation of laminated sediments on the continental margin off Pakistan: the effects of sediment provenance and sediment redistribution

2001

Abstract The sedimentary processes and sediment sources contributing to the formation of laminated sediments along the upper slope off Pakistan are unravelled using inorganic bulk sediment geochemistry of 43 surface cores from the Pakistani continental margin and additional geochemical and Pb and Nd-isotope data for different types of layers. An important process everywhere along the margin is redeposition of fluvial-derived detritus from the shelf onto the slope. This process is of considerably higher intensity along the Makran margin than on the Indus margin. Trace element enrichment related to early diagenesis or surface productivity, which is commonly detectable in bulk sediment composi…

2020

Although volcanic eruptions represent short periods in the whole history of a volcano, the large amount of loose pyroclastic material produced, combined with aeolian processes, can lead to continuous, long-lasting reworking of volcanic products. Driven by wind, these processes significantly influence the geomorphology and prolong the impacts of eruptions on exposed communities and ecosystems. Since such phenomena are of interest to scientists from a range of disciplines (e.g. volcanology, atmospheric and soil sciences), a well-defined, common nomenclature is necessary to optimize the multidisciplinary characterisation of both processes and deposits. We, therefore, first describe ash wind-re…

Rhyolitic dykes of Paros Island, Cyclades

2005

Abstract The discovery of rhyolitic dykes from the NE part of the island of Paros is described here for the first time. The dykes that can be mapped for a length of ca. 1.1 km are striking about 6° and 38° NE. The width reaches up to 11m maximum. The rhyolitic rocks are porphyric with a fine-grained matrix of mainly feldspar, quartz, some biotites and opaques. K-feldspar, biotite and plagioclase occur as phenocrysts, and mafic-intermediate enclaves are common. At the chilled margin in contact to the gneissic country rocks the dykes are vitric. There, the enclaves have been preserved from contact reaction with the melt and alteration effects and show primary igneous minerals such as clinopyr…