La ricerca post-qualitativa e gli interventi formativi della CHAT: Validità epistemologica e superamento dei problemi di metodo

Cultural-historical activity theory (CHAT) appears to match the tenets of post-qualitative inquiry. However, post-qualitative inquiry is credited with being averse to method and to adopt post-modernist stances that are not consistent with CHAT’s structured reading of social reality. Notwithstanding this, it is possible to propose an interpretation of post-qualitative inquiry that overcomes such conceptual challenges. This article tackles the issue both theoretically and with reference to the way current CHAT research is undertaken. First, we propose post-qualitative research should be understood as compliant with post-Gettier epistemological standpoints. Second, we show that CHAT-inspired formative interventions are both educational in nature and, given their approach to learning processes, display the core features of post-qualitative research. Given CHAT’s distinction between immanent aspects of social reality and methods tailored to tackle local issues, post-qualitative inquiry is justified in retaining its flexible—almost anarchic—methodology while, at the same time, enjoying epistemological soundness.La teoria dell’attività storico-culturale (CHAT) mostra di corrispondere ai principi della ricerca post-qualitativa. Tuttavia, la ricerca post-qualitativa si oppone al metodo e adotta posizioni post-moderniste che non paiono coerenti con la visione strutturata della realtà sociale promossa dalla CHAT. Ciononostante, proponiamo un’interpretazione della ricerca post-qualitativa che supera tali difficoltà concettuali. Questo articolo affronta la questione sia teoricamente che con riferimento al modo in cui si svolge l’attuale ricerca in seno alla CHAT. Per prima cosa, proponiamo di collocare la ricerca post-qualitativa entro il quadro dell’epistemologia post-Gettier. Successivamente, mostriamo che gli interventi formativi ispirati alla CHAT hanno sia carattere educativo che investigativo in virtù del loro approccio ai processi di apprendimento. Poiché la CHAT distingue tra aspetti immanenti della realtà sociale e metodi costruiti su misura per affrontare problemi locali, la ricerca post-qualitativa risulta giustificata nel preservare una metodologia flessibile—quasi anarchica—e, parimenti, godere di validità epistemologica

Update on Clinical Evidence Supporting Hemodiafiltration

The aim of this chapter is to define hemodiafiltration target efficiency, to clarify the concept of “optimal convective dose,” and to facilitate hemodiafiltration (HDF) implementation in clinical practice by addressing the need for the establishment of best clinical practices for HDF. The approach taken was to conduct a comprehensive summary of clinical evidence supporting HDF. Convective dose is the total ultrafiltered volume and is complementary to diffusive dose (urea Kt/V) as a dose‐dependent parameter. It can be quantified and adjusted to patient characteristics. Factors affecting convective dose are discussed: patient characteristics, prescription‐dependent factors, and technical and machine‐dependent factors. The key issue of HDF prescription and implementation of best practices is addressed as are intermediary and endpoint clinical outcomes. The main messages are as follows: (1) HDF is safe and effective provided that best clinical practices are followed and the right convective dose is delivered; (2) HDF is easy to perform with new technology; and (3) depending on the convection volume, HDF reduces all‐cause and cardiovascular mortality. Open challenges remain, namely, the implementation of best practices to (a) achieve optimal convection volume, (b) define patient subsets that would benefit more from HDF, and (c) evaluate new tools that fine‐tune HDF prescription according to individual patient needs

Anthropogenic impact on river basins: temporal evolution of sediment classes and accumulation rates in the Northern Tyrrhenian Sea, Italy

Abstract In this study, sedimentological and geochronological data from sections of a core (GRT50) collected in the Northern Latium coastal area were compared to data on pluviometric (rainfall) trends, river flows and the temporal evolution of human interventions in the three most important hydrographic basins (Mignone, Marta and Fiora) of this coastal area. The statistical analysis of pluviometric trends identified variations due to a decreasing trend in the Fiora river basin, whereas in the two other locations the decrease was not so significant. Data from the sedimentological analysis of the core confirmed a progressive decrease in the sandy component, which declined from about 30% to the current level of 7% over the last 36 years. There was no significant variation in the sediment mass accumulation rates (MAR), which were characterized by an almost cyclic trend that was probably determined by the most intense floods in the study area. The results revealed that the variations caused by the fluvial processes have affected the water runoff of the Fiora River, and that the consequent decrease in the sand production has been responsible for the recession of beaches in the coastal area between Tarquinia and Montalto di Castro

Microwave Inter-Connections and Switching by means of Carbon Nano-tubes

In this work, carbon nanotube (CNT) based interconnections and switches will be reviewed, discussing the possibility to use nanotubes as potential building blocks for signal routing in microwave networks. In particular, theoretical design of coplanar waveguide (CPW), micro‐strip single‐pole‐single‐throw (SPST) and single‐pole‐double‐throw (SPDT) devices has been performed to predict the electrical performances of CNT‐based RF switching configurations. Actually, by using the semiconductor‐conductor transition obtained by properly biasing the CNTs, an isolation better than 30 dB can be obtained between the ON and OFF states of the switch for very wide bandwidth applications. This happens owing to the shape deformation and consequent change in the band‐gap due to the external pressure caused by the electric field. State‐of‐art for other switching techniques based on CNTs and their use for RF nano‐interconnections is also discussed, together with current issues in measurement techniques

A Novel Particle/Photon Detector Based on a Superconducting Proximity Array of Nanodots

The current frontiers in the investigation of high-energy particles demand for new detection methods. Higher sensitivity to low-energy deposition, high-energy resolution to identify events and improve the background rejection, and large detector masses have to be developed to detect even an individual particle that weakly interacts with ordinary matter. Here, we will describe the concept and the layout of a novel superconducting proximity array which show dynamic vortex Mott insulator to metal transitions, as an ultra-sensitive compact radiation-particle detector

Trace-metal distribution and ecological risk assessment in sediments of a sheltered coastal area (Gulf of Gaeta, central-eastern Tyrrhenian Sea, Italy) in relation to hydrodynamic conditions

This study investigates the relationship between sediment contamination and hydrodynamic conditions in the Gaeta Gulf (Tyrrhenian Sea, Italy), an anthropogenically impacted and sheltered coastal area. The pollution levels, potential toxicity, and ecological risk of trace metals were analysed in 16 sediment sampling sites using Sediment Quality Guidelines (SQGs), the Adverse Effect Index (AEI), and the Mean ERM Quotient (m-ERM-Q). The bottom shear stress of the study area, evaluated using an annual simulation of a 3D numerical model, was used to calculate a new Sediment Mobilisation Index (SMI) that detects the coastal zones where a low probability of sediment resuspension occurs. As, Ni, and Cu concentrations exceeded the Threshold Effects Level (TEL) guideline value and AEI limit in several sampling sites, indicating their ability to produce adverse effects on biota. Moreover m-ERM-Q showed the highest values of potential ecological risk in most of the sampling sites located in the inner part of the Gulf of Gaeta. In this area, the highest SMI values were also identified, demonstrating that there is a tight relationship between the two indexes (R2 = 0.8214). The application of SMI in sheltered areas will help achieve high performance of monitoring and hazard assessment tools through obtaining predictable responses on hotspot identification

Interlayer potassium and its neighboring atoms in micas : Crystal-chemical modeling and XANES spectroscopy

A detailed description of the interlayer site in trioctahedral true micas is presented based on a statistical appraisal of crystal-chemical, structural, and spectroscopic data determined on two sets of trioctahedral micas extensively studied by both X-ray diffraction refinement on single crystals (SC-XRD) and X-ray absorption fine spectroscopy (XAFS) at the potassium K -edge. Spectroscopy was carried out on both random powders and oriented cleavage flakes, the latter setting taking advantage of the polarized character of synchrotron radiation. Such an approach (AXANES) is shown to be complementary to crystal-chemical investigation based on SC-XRD refinement. However, the results are not definitive as they focus on few samples having extreme features only (e.g., end-members, unusual compositions, and samples with extreme and well-identified substitution mechanisms). The experimental absorption K -edge (XANES) for potassium was decomposed by calculation and extrapolated into a full in-plane absorption component (σ||) and a full out-of-plane absorption component (σ⊥). These two patterns reflect different structural features: σ|| represents the arrangement of the atoms located in the mica interlayer space and facing tetrahedral sheets; σ⊥ is associated with multiple-scattering interactions entering deep into the mica structure, thus also reflecting interactions with the heavy atoms (essentially Fe) located in the octahedral sheet. The out-of-plane patterns also provide insights into the electronic properties of the octahedral cations, such as their oxidation states (e.g., Fe2+ and Fe3+) and their ordering (e.g., trans - vs. cis -setting). It is also possible to distinguish between F- and OH-rich micas due to peculiar absorption features originating from the F vs. OH occupancy of the O4 octahedral site. Thus, combining crystal-chemical, structural, and spectroscopic information is shown to be a practical method that allows, on one hand, assignment of the observed spectroscopic features to precise structural pathways followed by the photoelectron within the mica structure and, on the other hand, clarification of the amount of electronic interactions and forces acting onto the individual atoms at the various structural sites