Obsidians of Pantelleria (Strait of Sicily): A Petrographic, Geochemical and Magnetic Study of Known and New Geological Sources

This paper provides new petrochemical and paleomagnetic data from obsidian sub-sources on the island of Pantelleria, exploited since the Neolithic. Data has been obtained from 14 obsidian samples from 4 locations: Fossa della Pernice (2 sites), Salto la Vecchia and Balata dei Turchi. Here, we aim to better characterize these obsidians using a cross-disciplinary and multi-analytical approach, to further understand their archaeological significance. Major element analyses (EMP) have enabled two compositional super-groups to be distinguished: (i) Fossa della Pernice, less peralkaline and (ii) Balata dei Turchi-Salto la Vecchia, distinctly more peralkaline and having almost identical chemical patterns. Trace element analyses (LA-ICP-MS) corroborate major element groupings, with the Balata dei Turchi-Salto la Vecchia super-group being further characterized by a pronounced negative europium anomaly. Glass H2O contents (FT-IR) reveal an overlap among all the sub-sources (H2O = 0.1-0.3 wt. %). Magnetic methods have refined the petrochemical groupings, permitting further distinction between Balata dei Turchi-Salto La Vecchia and the Fossa della Pernice super-groups. The occurrence of sub-microscopic (< 1 μm) ferromagnetic minerals results in different magnetic susceptibility and Natural Remanent Magnetization values and allows the best distinction among the products from the chosen sites. When compared with obsidian tools excavated from Bronze-age settlements on the island of Ustica (230 km NE of Pantelleria), 12% are distinctly peralkaline, indicating their provenance to be from the Balata dei Turchi sub-source

Megawatt power generation of the dual-frequency gyrotron for TCV at 84 and 126 GHz, in long pulses

In the frame of the TCV Tokamak upgrade, two 84/126 GHz/2 s dual frequency gyrotrons designed by SPC and KIT and manufactured by THALES will be added to the existing EC-System. The first unit has been delivered to EPFLSPC and tested. In the commissioning configuration, a matching optics unit (MOU) is connected to the gyrotron window. The RF is then coupled to the HE11 mode of a 63.5mm corrugated waveguide and dissipated in a load procured by CNR after 4m of waveguide and 2 miter bends. Owing to the flexible triode gun design giving the possibility to adjust the pitch angle parameter, the specifications were met at both frequencies. At 84 GHz (TE17,5 mode), a power of 0.930 MW was measured in the calorimeter, with a pulse duration of 1.1 s. At the high frequency (126 GHz, TE26,7 mode), a power of 1.04 MW was reached for a pulse length of 1.2 s. Accounting for the load reflection and the ohmic losses in the various subcomponents of the transmission line and the tube, it is estimated that the output power at the gyrotron window is in excess of 1 MW at both frequencies, with an electronic efficiency of 32% and 34% at 84 GHz and 126 GHz respectively. The gyrotron behavior is remarkably robust and reproducible, and the pulse length is limited by external systems that will be improved shortly

Status of EU\u27s contribution to the ITER EC system

The electron cyclotron (EC) system of ITER for the initial configuration is designed to provide 20MW of RF power into the plasma during 3600s and a duty cycle of up to 25% for heating and (co and counter) non-inductive current drive, also used to control the MHD plasma instabilities. The EC system is being procured by 5 domestic agencies plus the ITER Organization (IO). F4E has the largest fraction of the EC procurements, which includes 8 high voltage power supplies (HVPS), 6 gyrotrons, the ex-vessel waveguides (includes isolation valves and diamond windows) for all launchers, 4 upper launchers and the main control system. F4E is working with IO to improve the overall design of the EC system by integrating consolidated technological advances, simplifying the interfaces, and doing global engineering analysis and assessments of EC heating and current drive physics and technology capabilities. Examples are the optimization of the HVPS and gyrotron requirements and performance relative to power modulation for MHD control, common qualification programs for diamond window procurements, assessment of the EC grounding system, and the optimization of the launcher steering angles for improved EC access. Here we provide an update on the status of Europe’s contribution to the ITER EC system, and a summary of the global activities underway by F4E in collaboration with IO for the optimization of the subsystems

Recent results from the electron cyclotron heated plasmas in Tokamak à Configuration Variable (TCV)

In noninductively driven discharges, 0.9 MW second harmonic (X2) off-axis co-electron cyclotron current drive deposition is combined with 0.45 MW X2 central heating to create an electron internal transport barrier (eITB) in steady plasma conditions resulting in a 1.6-fold increase of the confinement time (tau(Ee)) over ITER-98L-mode scaling. The eITB is associated with a reversed shear current profile enhanced by a large bootstrap current fraction (up to 80%) and is sustained for up to 10 current redistribution times. A linear dependence of the confinement improvement on the product of the global shear reversal factor (q(0)/q(min)) and the reversed shear volume (rho(q-min)(2)) is shown. In other discharges heated with X2 the sawteeth are destabilized (respectively stabilized) when heating just inside (respectively outside) the q=1 surface. Control of the sawteeth may allow the avoidance of neoclassical tearing modes that can be seeded by the sawtooth instability. Results on H-mode and highly elongated plasmas using the newly completed third harmonic (X3) system and achieving up to 100% absorption are also discussed, along with comparison of experimental results with the TORAY-GA ray tracing code [K. Matsuda, IEEE Trans. Plasma Sci. PS-17, 6 (1989); R. H. Cohen, Phys. Fluids 30, 2442 (1987)]. (C) 2003 American Institute of Physics

Paleomagnetic Evidence for Pre-21 Ma Independent Drift of South Sardinia From North Sardinia-Corsica: "Greater Iberia" Versus Europe

It is unanimously acknowledged that the Corsica-Sardinia microplate rotated counterclockwise (CCW) by 40-50 degrees between 21 and 15 Ma, synchronous with Liguro-Provencal Basin oceanic spreading. Conversely, 60-120 degrees CCW rotations with respect to Europe from Sardinia (Permian dykes, volcanics and sediments, Mesozoic carbonates, and lower Eocene limestones) have been interpreted to be related to (a) late Permian intra-Pangea shear events, (b) Aptian Iberia rotation, and (c) Eocene Valais Ocean closure. We report paleomagnetic data from 31 red-bed sites from the mid-late Eocene (45-32 Ma) Cixerri Fm. exposed in SW Sardinia. Characteristic paleomagnetic directions from 25 dual polarity sites (240 samples) define an 86 +/- 7 degrees CCW rotation. We suggest that a S Sardinia block located NE of Balearic Islands rotated 30 degrees CCW during the 30-21 Ma Liguro-Provencal rifting, and was decoupled from N Sardinia along the left-lateral Nuoro fault. After 21 Ma, Corsica-Sardinia underwent a drift-related 60 degrees CCW rotation as a whole. A re-analysis of available paleomagnetic results shows that Permian data from N Sardinia-Corsica align with European directions considering a 60 degrees CCW rotation, whereas Permian and mid Jurassic data from S Sardinia match European directions only after considering a similar to 35 degrees CCW Iberia rotation besides the 90 degrees post-Eocene event. We suggest that S Sardinia was part of Iberia, and rotated CCW during both Aptian Iberia drift and Oligo-Miocene Liguro-Provencal opening. Our data, along with recent paleomagnetic results from Calabria, suggest that S Sardinia, Balearic Islands, Calabria, Peloritan, Kabylies, and Alboran were fragments of "Greater Iberia," joined to Iberia before 30 Ma Liguro-Provencal rifting

Transpression and the build-up of the Cordillera: The example of the Bucaramanga fault (Eastern Cordillera, Colombia)

Widespread wrench tectonics have been described along the northern Andes. The Bucaramanga fault, described as sinistral strike-slip, bounds the high Santander Massif. We combine structural and thermochronological data from the central-southern portion of the fault to investigate the vertical displacement. The structural survey data show old phases of activity preserved in the host rocks along the fault trace, with the superimposition of different generations of slickenlines, and both strike-slip and dip-slip kinematics indicators. New and previous thermochronological data show that differential exhumation of the fault walls has been ongoing for the last 50 Ma. The hanging wall, the Santander Massif, records, in the central portion, decreasing exhumation rates from the early Miocene to the mid-to late Miocene and, in the southern portion, constant rates from the Late Oligocene to the Pliocene. Combining such observations, the thermochronological offset resulting from the relative motion of the two fault walls is comparable with the observed drop in elevation across the fault, suggesting that the present topography of the Santander Massif is related to vertical movement along the Bucaramanga fault. We infer that the fault has a significant Neogene reverse component, consistent with the present day horizontal global positioning system vector data, long-term exhumation rates and the structural assemblage

Constraints on the Cenozoic Deformation of the Northern Eastern Cordillera, Colombia

The Eastern Cordillera of Colombia rose to maximum elevations of >5 km during the Cenozoic by inversion of a Mesozoic rift basin. Previous studies proposed that the exhumation of the Eastern Cordillera increased from ~6 Ma to the present due to the interplay between tectonic shortening and climate. In this study, we integrate new field observations, structural data, low-temperature thermochronology, thermobarometry, and vitrinite reflectance along a section through the Tablazo, Cocuy, and Llanos regions to estimate the amount of shortening and the exhumation history. Our results indicate that shortening started as early as the latest Maastrichtian-Paleocene in the Tablazo and Cocuy regions. Exhumation migrated eastward, starting in the Paleocene in the west and continuing in the Miocene in the east. The amount and rate of exhumation peaked in the Cocuy region with values of <5 km and < 0.4 km/Ma, respectively. At the highest elevations in the Cocuy Sierra, we also found evidence of a low-pressure/high-temperature metamorphic overprint, possibly related to shallow and local magmatic intrusions that occurred in the Late Miocene. Our cross-section interpretation suggests a low amount of shortening (13%) that is mainly accommodated by high-angle inverted faults and by the frontal thrust system. The presence of shallow magmatic bodies, moderate exhumation, and low shortening raises questions about the processes (isostatic versus dynamic) that drove the topographic growth of the high Cocuy Sierra

On the Role of Developer’s Scattered Changes in Bug Prediction

The importance of human-related factors in the introduction of bugs has recently been the subject of a number of empirical studies. However, such factors have not been captured yet in bug prediction models which simply exploit product metrics or process metrics based on the number and type of changes or on the number of developers working on a software component. Previous studies have demonstrated that focused developers are less prone to introduce defects than non focused developers. According to this observation, software components changed by focused developers should also be less error prone than software components changed by less focused developers. In this paper we capture this observation by measuring the structural and semantic scattering of changes performed by the developers working on a software component and use these two measures to build a bug prediction model. Such a model has been evaluated on five open source systems and compared with two competitive prediction models: the first exploits the number of developers working on a code component in a given time period as predictor, while the second is based on the concept of code change entropy. The achieved results show the superiority of our model with respect to the two competitive approaches, and the complementarity of the defined scattering measures with respect to standard predictors commonly used in the literature