1,390 research outputs found
Sulfur and oxygen isotope compositions of Upper Triassic sulfates from northern Apennines (Italy) : paleogeographic and hydrogeochemical implications
Upper Triassic bedded evaporite sulfate of the Burano Formation outcropping at Cerreto Pass between Tuscany and Emilia-Romagna in the Northern Apennines were analyzed for sulfur and oxygen isotope compositions, yielding d34S and d18O values of 15.5±0.4‰ and 10.8±1.2‰, respectively (mean ±99% confidence intervals). Combining these values with those of other Burano Formation sulfate deposits along the Apennine chain, mean for d34S and d18O values are obtained (15.2±0.2‰ and 10.9±0.5‰, respectively). These isotopic signatures are interpreted as preserved primary features, despite the fact that the Burano Formation underwent anchizone to epizone metamorphism during the Apennine orogenesis. An overall d18O value of 10.9±1.5‰ (mean ± pooled standard deviation), obtained by combining consistent sets of data from Italy and Spain, closely approaches that of gypsum deposited from the Tethys ocean during the Late Triassic. In addition, reviewing the isotope data published on Late Triassic evaporite sulfates from the Mediterranean area and abroad, several d34S values appear to be lower than the inferred primary isotopic signature, and seemly decrease from East to West in the Mediterranean region, suggesting a similar trend for the Tethys ocean sulfate. Possibly, 34S-depleted sulfate entered the ocean through oxidation of volcanic SO2 emitted in the atmosphere and degassed from the seafloor during the development of Late Triassic rifting. On the other hand, positive shifts of d34S and d18O values also occur, defining a common trend that may be related to synsedimentary biological effects or post-depositional metasomatic-metamorphic effects, the latter affecting particularly the d18O signature. Therefore, the d34S and d18O signatures of evaporite sulfate may provide a like "slide-rule" diagram to distinguish between isotopic effects related to biological or abiological processes, thus contributing to the reconstruction of paleoenvironments and paleogeographic settings. Based on the d34S-d18O "slide-rule", the isotopic composition of sulfate dissolved in spring and stream waters of northern Tuscany was interpreted in terms of origin of the sulfate and modifying processes in solution. It was concluded that sulfate in springs derives from Upper Triassic evaporite existing locally at depth (Burano Formation), whereas sulfate in streams is manifestly a mixture of Burano Formation sulfate with supergene sulfate from oxidation of sulfide in the rocks. In sulfurous springs, both sulfur and oxygen isotope fractionations with respect to the source sulfate signatures may be ascribed to bacterial effects. However, the oxygen isotope exchange of sulfate with water should have been a very minor process as supported by the nearsurface temperature values estimated by sulfate-water oxygen isotope thermometry
Tracking power system events with accuracy-based PMU adaptive reporting rate
Fast dynamics and transient events are becoming more and more frequent in power systems, due to the high penetration of renewable energy sources and the consequent lack of inertia. In this scenario, Phasor Measurement Units (PMUs) are expected to track the monitored quantities. Such functionality is related not only to the PMU accuracy (as per the IEC/IEEE 60255-118-1 standard) but also to the PMU reporting rate (RR). High RRs allow tracking fast dynamics, but produce many redundant measurement data in normal conditions. In view of an effective tradeoff, the present paper proposes an adaptive RR mechanism based on a real-time selection of the measurements, with the target of preserving the information content while reducing the data rate. The proposed method has been tested considering real-world datasets and applied to four different PMU algorithms. The results prove the method effectiveness in reducing the average data throughput as well as its scalability at PMU concentrator or storage level
Sulfur and oxygen isotope compositions of Upper Triassic sulfates from Northerm Apennines (Italy): palaeogeographic and hidrogeochemical implications
Upper Triassic bedded evaporite sulfate of the Burano Formation outcropping at Cerreto Pass between Tuscany and Emilia-Romagna in the Northern Apennines were analyzed for sulfur and oxygen isotope compositions, yielding d34S and d18O values of 15.5±0.4‰ and 10.8±1.2‰, respectively (mean ±99% confidence intervals). Combining these values with those of other Burano Formation sulfate deposits along the Apennine chain, mean for d34S and d18O values are obtained (15.2±0.2‰ and 10.9±0.5‰, respectively). These isotopic signatures are interpreted as preserved primary features, despite the fact that the Burano Formation underwent anchizone to epizone metamorphism during the Apennine orogenesis. An overall d18O value of 10.9±1.5‰ (mean ± pooled standard deviation), obtained by combining consistent sets of data from Italy and Spain, closely approaches that of gypsum deposited from the Tethys ocean during the Late Triassic. In addition, reviewing the isotope data published on Late Triassic evaporite sulfates from the Mediterranean area and abroad, several d34S values appear to be lower than the inferred primary isotopic signature, and seemly decrease from East to West in the Mediterranean region, suggesting a similar trend for the Tethys ocean sulfate. Possibly, 34S-depleted sulfate entered the ocean through oxidation of volcanic SO2 emitted in the atmosphere and degassed from the seafloor during the development of Late Triassic rifting. On the other hand, positive shifts of d34S and d18O values also occur, defining a common trend that may be related to synsedimentary biological effects or post-depositional metasomatic-metamorphic effects, the latter affecting particularly the d18O signature. Therefore, the d34S and d18O signatures of evaporite sulfate may provide a like “slide-rule” diagram to distinguish between isotopic effects related to biological or abiological processes, thus contributing to the reconstruction of paleoenvironments and paleogeographic settings. Based on the d34S-d18O “slide-rule”, the isotopic composition of sulfate dissolved in spring and stream waters of northern Tuscany was interpreted in terms of origin of the sulfate and modifying processes in solution. It was concluded that sulfate in springs derives from Upper Triassic evaporite existing locally at depth (Burano Formation), whereas sulfate in streams is manifestly a mixture of Burano Formation sulfate with supergene sulfate from oxidation of sulfide in the rocks. In sulfurous springs, both sulfur and oxygen isotope fractionations with respect to the source sulfate signatures may be ascribed to bacterial effects. However, the oxygen isotope exchange of sulfate with water should have been a very minor process as supported by the nearsurface temperature values estimated by sulfate-water oxygen isotope thermometry
Slip-rates of blind thrusts in slow deforming areas: examples from the Po Plain (Italy)
We calculate Plio-Pleistocene slip rates on the blind thrusts of the outer Northern Apennines fronts,
that are the potential sources of highly damaging earthquakes, as shown by the MW 6.1-6.0, 2012
Emilia-Romagna seismic sequence. Slip rates are a key parameter for understanding the
seismogenic potential of active fault systems and assessing the seismic hazard they pose, however,
they are difficult to calculate in slow deforming areas like the Po Plain where faulting and folding is
mostly blind. To overcome this, we developed a workflow which included the preparation of a
homogeneous regional dataset of geological and geophysical subsurface information, rich in Plio-
Pleistocene data. We then constructed 3D geological models around selected individual structures
to decompact the clastic units and restore the slip on the fault planes. The back-stripping of the
differential compaction eliminates unwanted overestimation of the slip rates due to compactioninduced
differential subsidence. Finally, to restore the displacement we used different methods
according to the deformation style, i.e. Fault Parallel Flow for faulted horizons, trishear and elastic
dislocation modeling for fault-propagation folds. The result of our study is the compilation of a slip
rate database integrating former published values with 28 new values covering a time interval from
the Pliocene to the present. It contains data on 14 individual blind thrusts including the Mirandola
thrust, seismogenic source of the 29 May 2012, MW 6.0 earthquake. Our study highlights that the
investigated thrusts were active with rates ranging between 0.1-1.0 mm/yr during the last 1.81 Myr.
The Mirandola thrust slipped at 0.86±0.38 mm/yr during the last 0.4 Myr. These rates calculated
with an homogeneous methodology through the entire Po Plain can be charged entirely to the thrust
activity and not to secondary effects like the differential compaction of sediments across the
structures
A decentralized, patient-centered approach to diabetes disease management in the primary care setting
Although many disease management programs have been developed for diabetes, no single design has proved best for all providers and patient populations. Cost effectiveness is especially relevant to diabetes programs because significant costs of the disease may come from complications that occur later in life, while the costs of the program are incurred immediately. For this reason, diabetes disease management programs with positive outcomes and low implementation costs are of particular importance. We report here on the outcomes of a pilot test of the Steps to Health program developed by Abbott Laboratories. The Steps to Health program was designed to improve patients\u27 compliance for their diabetes care by increasing their knowledge and understanding of diabetes. The pilot test format utilized a decentralized approach to implement the Steps to Health program and included assessments of clinical, process, and quality-of-life outcomes. The study used a prospective, observational, pre-post design. Patients were assessed at enrollment and at 6 months. The primary clinical outcome was glycemic control, as measured by HbA1c. For the 70 patients (18% of enrollment) with complete baseline and endpoint data, mean decrease in HbA1c was 1.7% (p \u3c 0.0001). Clinical process measures of preventive diabetes care showed minor changes in rates between the pre- and postenrollment periods. There was also significant improvement in patient satisfaction regarding their knowledge of diabetes, overall ability to take care of diabetes, and helpfulness of the information received. These results suggest that a diabetes disease management program that is relatively inexpensive and easy to implement, centered on patient education in self-management, can achieve clinically significant improvements in glycemic control for a specific period of time (6 months) and result in a high level of patient satisfaction
The role of pre-existing discontinuities in the development of extensional faults: an analog modeling perspective
Several mountainous regions are currently affected by syn- or post-orogenic active extension. We investigate how a newly-formed normal fault interacts with structures inherited from a previous contractional phase. To this end, we use analog models that adopt an innovative technique for performing a precut that mimics such inherited structures into a clay layer; this clay layer is laid on top of a master fault simulated by two rigid blocks sliding along an inclined plane. We carry out six experiments with variously oriented precuts and compare the results with those obtained in a reference isotropic experiment. All other conditions are identical for all seven realizations. Fault evolution is monitored by taking closely-spaced snapshots analyzed through the Digital Image Correlation method. We find that the upward propagation of the normal fault can be either accelerated or decelerated depending on the presence of a precut and its orientation. Such precuts can also promote or inhibit the formation of bending-moment faults. These interactions between master fault and precut also affect the shape of the fault-related syncline-anticline pair
Self-similarity and power-like tails in nonconservative kinetic models
In this paper, we discuss the large--time behavior of solution of a simple
kinetic model of Boltzmann--Maxwell type, such that the temperature is time
decreasing and/or time increasing. We show that, under the combined effects of
the nonlinearity and of the time--monotonicity of the temperature, the kinetic
model has non trivial quasi-stationary states with power law tails. In order to
do this we consider a suitable asymptotic limit of the model yielding a
Fokker-Planck equation for the distribution. The same idea is applied to
investigate the large-time behavior of an elementary kinetic model of economy
involving both exchanges between agents and increasing and/or decreasing of the
mean wealth. In this last case, the large-time behavior of the solution shows a
Pareto power law tail. Numerical results confirm the previous analysis
The dissipative linear Boltzmann equation for hard spheres
We prove the existence and uniqueness of an equilibrium state with unit mass
to the dissipative linear Boltzmann equation with hard--spheres collision
kernel describing inelastic interactions of a gas particles with a fixed
background. The equilibrium state is a universal Maxwellian distribution
function with the same velocity as field particles and with a non--zero
temperature lower than the background one, which depends on the details of the
binary collision. Thanks to the H--theorem we then prove strong convergence of
the solution to the Boltzmann equation towards the equilibrium.Comment: 17 pages, submitted to Journal of Statistical Physic
Ozone in Lombardy: Years 1998-1999
Photochemical pollutants, especially ozone, have reached very high levels in Lombardy in recent years, with peaks of up to 150 ppb in late spring and summer. Lombardy, lying on the Po Plain, supports a large number of cities and
industries and these, along with heavy traffic, produce copious amounts of primary pollutants such as nitrogen oxides and numerous volatile organic compounds. Furthermore,
the peculiar orography of this region fosters the stagnation of air masses on a basin-scale and the presence of diurnal breezes towards northern areas, along with the evolution of the Mixing Layer, spread the polluted air masses over a large territory. Numerous stations in Lombardy give the concentrations of ozone and of nitrogen oxides. In this paper, ozone measurements carried out at the plain area around Milan and at pre-alpine sites in the spring and summer 1998 and 1999 will be shown and discussed, focusing on the months of May and July. The study of temporal and spatial behaviour of ozone goes hand in hand with the analysis of the Boundary Layer’s evolution. A number of radon stations were operating in Milan and in other sites in Lombardy. Measurements of atmospheric concentrations of radon yield an index of atmospheric stability, of the formation of thermal inversion, of convective turbulence, and of the movement of air masses, and hence they are very relevant to the understanding of the conditions of atmospheric pollutants
CHARM facility remotely controlled platform at CERN: A new fault-tolerant redundant architecture
Many power electronics applications require high tolerance to faults such as short circuit or open circuit of the control signals. One such application is the CERN High energy AcceleRator Mixed-field (CHARM) facility, where maintenance may be precluded for long periods of time due to radiation and, therefore, high reliability is necessary.
A redundant interconnection architecture for the control signals is proposed, where each signal is individually processed by different CPUs and transmitted through separate interconnection lines. During normal operation, the CPUs are synchronized and produce the same signals. The purpose of the proposed hardware and firmware strategy is to allow the actuator to continue operating even in case of fault; regardless of the fault type (open circuit, short circuit to ground or to positive supply), a fault on one of the parallel lines would not inhibit the correct operation of the remaining line.
This solution can be used to control the movements of a target system using a remote joystick in a safe environment. The architecture features reliable transmission of PWM signals driving a half-bridge power converter.
Moreover, it is possible to extend it to any type of converter such as three-phase bridges, three-level NPC, or buck-boost converters.
Simulations and experimental results show a good agreement, proving the effectiveness of the proposed fault tolerant circuitry
- …