Local log-law of the wall: numerical evidences and reasons

Numerical studies performed with a primitive equation model on two-dimensional sinusoidal hills show that the local velocity profiles behave logarithmically to a very good approximation, from a distance from the surface of the order of the maximum hill height almost up to the top of the boundary layer. This behavior is well known for flows above homogeneous and flat topographies (``law-of-the-wall'') and, more recently, investigated with respect to the large-scale (``asymptotic'') averaged flows above complex topography. Furthermore, this new-found local generalized law-of-the-wall involves effective parameters showing a smooth dependence on the position along the underlying topography. This dependence is similar to the topography itself, while this property does not absolutely hold for the underlying flow, nearest to the hill surface.Comment: 9 pages, Latex, 2 figure

Does the Danube exist? Versions of reality given by various regional climate models and climatological datasets

We present an intercomparison and verification analysis of several regional climate models (RCMs) nested into the same run of the same Atmospheric Global Circulation Model (AGCM) regarding their representation of the statistical properties of the hydrological balance of the Danube river basin for 1961-1990. We also consider the datasets produced by the driving AGCM, from the ECMWF and NCEP-NCAR reanalyses. The hydrological balance is computed by integrating the precipitation and evaporation fields over the area of interest. Large discrepancies exist among RCMs for the monthly climatology as well as for the mean and variability of the annual balances, and only few datasets are consistent with the observed discharge values of the Danube at its Delta, even if the driving AGCM provides itself an excellent estimate. Since the considered approach relies on the mass conservation principle and bypasses the details of the air-land interface modeling, we propose that the atmospheric components of RCMs still face difficulties in representing the water balance even on a relatively large scale. Their reliability on smaller river basins may be even more problematic. Moreover, since for some models the hydrological balance estimates obtained with the runoff fields do not agree with those obtained via precipitation and evaporation, some deficiencies of the land models are also apparent. NCEP-NCAR and ERA-40 reanalyses result to be largely inadequate for representing the hydrology of the Danube river basin, both for the reconstruction of the long-term averages and of the seasonal cycle, and cannot in any sense be used as verification. We suggest that these results should be carefully considered in the perspective of auditing climate models and assessing their ability to simulate future climate changes.Comment: 25 pages 8 figures, 5 table

Evaluation of an integrated system for classification, assessment and comparison of services for long-term care in Europe: the eDESDE-LTC study

The harmonization of European health systems brings with it a need for tools to allow the standardized collection of information about medical care. A common coding system and standards for the description of services are needed to allow local data to be incorporated into evidence-informed policy, and to permit equity and mobility to be assessed. The aim of this project has been to design such a classification and a related tool for the coding of services for Long Term Care (DESDE-LTC), based on the European Service Mapping Schedule (ESMS). Methods. The development of DESDE-LTC followed an iterative process using nominal groups in 6 European countries. 54 researchers and stakeholders in health and social services contributed to this process. In order to classify services, we use the minimal organization unit or "Basic Stable Input of Care" (BSIC), coded by its principal function or "Main Type of Care" (MTC). The evaluation of the tool included an analysis of feasibility, consistency, ontology, inter-rater reliability, Boolean Factor Analysis, and a preliminary impact analysis (screening, scoping and appraisal). Results: DESDE-LTC includes an alpha-numerical coding system, a glossary and an assessment instrument for mapping and counting LTC. It shows high feasibility, consistency, inter-rater reliability and face, content and construct validity. DESDE-LTC is ontologically consistent. It is regarded by experts as useful and relevant for evidence-informed decision making. Conclusion: DESDE-LTC contributes to establishing a common terminology, taxonomy and coding of LTC services in a European context, and a standard procedure for data collection and international comparison

The Soverato flood in Southern Italy: performance of global and limited-area ensemble forecasts

The predictability of the flood event affecting Soverato (Southern Italy) in September 2000 is investigated by considering three different configurations of ECMWF ensemble: the operational Ensemble Prediction System (EPS), the targeted EPS and a high-resolution version of EPS. For each configuration, three successive runs of ECMWF ensemble with the same verification time are grouped together so as to generate a highly-populated "super-ensemble". Then, five members are selected from the super-ensemble and used to provide initial and boundary conditions for the integrations with a limited-area model, whose runs generate a Limited-area Ensemble Prediction System (LEPS). The relative impact of targeting the initial perturbations against increasing the horizontal resolution is assessed for the global ensembles as well as for the properties transferred to LEPS integrations, the attention being focussed on the probabilistic prediction of rainfall over a localised area. At the 108, 84 and 60- hour forecast ranges, the overall performance of the global ensembles is not particularly accurate and the best results are obtained by the high-resolution version of EPS. The LEPS performance is very satisfactory in all configurations and the rainfall maps show probability peaks in the correct regions. LEPS products would have been of great assistance to issue flood risk alerts on the basis of limited-area ensemble forecasts. For the 60-hour forecast range, the sensitivity of the results to the LEPS ensemble size is discussed by comparing a 5-member against a 51-member LEPS, where the limited-area model is nested on all EPS members. Little sensitivity is found as concerns the detection of the regions most likely affected by heavy precipitation, the probability peaks being approximately the same in both configurations

Intercomparison of the northern hemisphere winter mid-latitude atmospheric variability of the IPCC models

We compare, for the overlapping time frame 1962-2000, the estimate of the northern hemisphere (NH) mid-latitude winter atmospheric variability within the XX century simulations of 17 global climate models (GCMs) included in the IPCC-4AR with the NCEP and ECMWF reanalyses. We compute the Hayashi spectra of the 500hPa geopotential height fields and introduce an integral measure of the variability observed in the NH on different spectral sub-domains. Only two high-resolution GCMs have a good agreement with reanalyses. Large biases, in most cases larger than 20%, are found between the wave climatologies of most GCMs and the reanalyses, with a relative span of around 50%. The travelling baroclinic waves are usually overestimated, while the planetary waves are usually underestimated, in agreement with previous studies performed on global weather forecasting models. When comparing the results of various versions of similar GCMs, it is clear that in some cases the vertical resolution of the atmosphere and, somewhat unexpectedly, of the adopted ocean model seem to be critical in determining the agreement with the reanalyses. The GCMs ensemble is biased with respect to the reanalyses but is comparable to the best 5 GCMs. This study suggests serious caveats with respect to the ability of most of the presently available GCMs in representing the statistics of the global scale atmospheric dynamics of the present climate and, a fortiori, in the perspective of modelling climate change.Comment: 39 pages, 8 figures, 2 table

Effect of peroxides on spermine transport in rat brain and liver mitochondria.

The polyamine spermine is transported into the matrix of various types of mitochondria by a specific uniporter system identified as a protein channel. This mechanism is regulated by the membrane potential; other regulatory effectors are unknown. This study analyzes the transport of spermine in the presence of peroxides in both isolated rat liver and brain mitochondria, in order to evaluate the involvement of the redox state in this mechanism, and to compare its effect in both types of mitochondria. In liver mitochondria peroxides are able to inhibit spermine transport. This effect is indicative of redox regulation by the transporter, probably due to the presence of critical thiol groups along the transport pathway, or in close association with it, with different accessibility for the peroxides and performing different functions. In brain mitochondria, peroxides have several effects, supporting the hypothesis of a different regulation of spermine transport. The fact that peroxovanadate can inhibit tyrosine phosphatases in brain mitochondria suggests that mitochondrial spermine transport is regulated by tyrosine phosphorylation in this organ. In this regard, the evaluation of spermine transport in the presence of Src inhibitors suggests the involvement of Src family kinases in this process. It is possible that phosphorylation sites for Src kinases are present in the channel pathway and have an inhibitory effect on spermine transport under regulation by Src kinases. The results of this study suggest that the activity of the spermine transporter probably depends on the redox and/or tyrosine phosphorylation state of mitochondria, and that its regulation may be different in distinct organs

Inversion kinematics at deep-seated gravity slope deformations revealed by trenching techniques

Abstract. We compare data from three deep-seated gravitational slope deformations (DSGSDs) where palaeoseismological techniques were applied in artificial trenches. At all trenches, located in metamorphic rocks of the Italian Alps, there is evidence of extensional deformation given by normal movements along slip planes dipping downhill or uphill, and/or fissures, as expected in gravitational failure. However, we document and illustrate – with the aid of trenching – evidence of reverse movements. The reverse slips occurred mostly along the same planes along which normal slip occurred, and they produced drag folds in unconsolidated Holocene sediments as well as the superimposition of substrate rocks on Holocene sediments. The studied trenches indicate that reverse slip might occur not only at the toe portions of DSGSDs but also in their central-upper portions. When the age relationships between the two deformation kinematics can be determined, they clearly indicate that reverse slips postdate normal ones. Our data suggest that, during the development of long-lived DSGSDs, inversion kinematics may occur in different sectors of the unstable rock mass. The inversion is interpreted as due either to locking of the frontal blocks of a DSGSD or to the relative decrease in the rate of downward movement in the frontal blocks with respect to the rear blocks

High operating temperature HgCdTe coupled cavity plasmonic infrared photodetectors

Increasing the operating temperature while enhancing detectivity is paramount for the advancement of HgCdTe infrared detectors. In this context, the integration of plasmonic nanostructures emerges as one of the most intriguing avenues, promising breakthroughs in infrared sensing capabilities. Multiphysics TCAD simulations of pin nanostructured focal plane photodetector arrays unveil the potential benefits of submicron absorber thicknesses, that promise detectivities more than twice as large as those provided by conventional 5 um-thick absorbers, besides enabling operating temperatures up to 260 K. Such performance increase is discussed through the combination of numerical simulations and quantum mechanical treatment based on the occupation number formalism, describing the interaction between plasmonic and optical cavity modes responsible for the spectral broadening of the optical response, allowing for good coverage of the entire mid-infrared band ([3,5] um)

Quantum Dot-Based Thin-Film III–V Solar Cells

In this work, we report our recent results in the development of thin-film III–V solar cells fabricated by epitaxial lift-off (ELO) combining quantum dots (QD) and light management structures. Possible paths to overcome two of the most relevant issues posed by quantum dot solar cells (QDSC), namely, the degradation of open circuit voltage and the weak photon harvesting by QDs, are evaluated both theoretically and experimentally. High open circuit voltage QDSCs grown by molecular beam epitaxy are demonstrated, both in wafer-based and ELO thin-film configuration. This paves the way to the implementation in the genuine thin-film structure of advanced photon management approaches to enhance the QD photocurrent and to further optimize the photovoltage. We show that the use of light trapping is essential to attain high-efficiency QDSCs. Based on transport and rigorous electromagnetic simulations, we derive design guidelines towards light-trapping enhanced thin-film QDSCs with efficiency higher than 28% under unconcentrated light, ambient temperature. If photon recycling can be fully exploited, 30% efficiency is deemed to be feasible. Towards this goal, results on the development and integration of optimized planar and micro-patterned mirrors, diffractive gratings and broadband antireflection coatings are presented