Stability and noise spectra of relative Loran-C frequency comparisons

Relative comparisons of Loran-C frequency transmissions between the master station of Catanzaro (Simeri Crichi) and the X, Z slave stations of Estartit (Spain) and Lampedusa (Italy) are carrying out by the GG LORSTA monitor station of the Mediterranean Sea Loran-C chain. These comparisons are able to emphasize the relative and, under certain conditions, the absolute rate of the emitting standard frequencies of the slave stations and some relevant statistical properties of the Loran-C Method for frequency transmission and time synchronization. The stability of each Loran-C frequency standard transmission is subject to perturbations, more or less known, due to the propagation medium and other causes. Following the Allan (1966) method for data processing, the performance of the relative rate of frequency of the transmissions of the X, Z slave stations are described calculating the standard deviation of a set of N frequency measurements from its mean averaged during sampling times. This standard deviation is designated as the measure of the stability of the Loran-C frequency transmission

Bilateral engagement of the occipito-temporal cortex in response to dance kinematics in experts

Previous evidence has shown neuroplastic changes in brain anatomy and connectivity associated with the acquisition of professional visuomotor skills. Reduced hemispherical asymmetry was found in the sensorimotor and visual areas in expert musicians and athletes compared with non-experts. Moreover, increased expertise with faces, body, and objects resulted in an enhanced engagement of the occipito-temporal cortex (OTC) during stimulus observation. The present study aimed at investigating whether intense and extended practice with dance would result in an enhanced symmetric response of OTC at an early stage of action processing. Expert ballet dancers and non-dancer controls were presented with videos depicting ballet steps during EEG recording. The observation of the moving dancer elicited a posterior N2 component, being larger over the left hemisphere in dancers than controls. The source reconstruction (swLORETA) of the negativity showed the engagement of the bilateral inferior and middle temporal regions in experts, while right-lateralized activity was found in controls. The dancers also showed an early P2 and enhanced P300 responses, indicating faster stimulus processing and subsequent recognition. This evidence seemed to suggest expertise-related increased sensitivity of the OTC in encoding body kinematics. Thus, we speculated that long-term whole-body practice would result in enriched and refined action processin

Ouabain-insensitive, Na-ATPase activity in pure suspensions of rat kidney proximal tubules

AbstractThe present work was undertaken to evaluate the distribution of the Na-ATPase activity in the different components of the rat kidney cortex. Suspensions of glomeruli, proximal and distal tubules were prepared following a collagenase digestion of outermost kidney cortex slices and a separation on a Percoll gradient. It was found that the Na-ATPase activity is higher in the fraction enriched in proximal tubules. The fraction enriched in glomeruli and in distal tubules show also a Na-ATPase activity, but it is lower

Multimodality characterization of tissue microstructure with Magnetic Resonance and Optical Spectroscopy

Cancer introduces changes in the microstructure of tissues, and different modalities can characterise specific features. Diffusion Magnetic Resonance investigates the diffusion of water molecules within the microstructure, providing contrast to describe the confinement of water in the different cytological compartments. The migration of photons and their polarisation status in a medium is conditioned by scattering and absorption where scattering is related to the micro and nanostructure. For the first time, we demonstrate the use of two modalities to inform a combined model describing microstructural features non-invasively. Diffusion MR and Optical Spectroscopy provide complementary information about the tissue, and a common model can be used to provide bio-markers indicating presence and staging a cancerous lesion. Here, the common model is fitted to the signals from each modality to inform a collective characterisation of the microstructure. A proof of concept on a sample (oil in water emulsion) is proposed to test the approach, where time-domain optical spectra have been combined with diffusion NMR echoes. To demonstrate the first steps towards clinical feasibility, a diffusion MR imaging, based on Oscillating Gradient Spin Echoes (OGSE), has been implemented to investigate the smallest elements of the microstructure of fixed samples obtained from two human colorectal cell lines. Diffusion OGSE MR imaging was then combined with polarised light spectroscopy. The ultimate aim is to provide an implementable method for clinical practice, where the optical modality can be acquired in gastroscopy, independently from the MRI imaging. The target is to diagnose colorectal cancer and stage the grade non-invasively. Furthermore, this work provides a method that can be extended to other modalities with minor changes

A topological weakening and softening map as simplified tool to assess the performances recovery of hybridized natural fiber reinforced composites subjected to alternate salt-fog/dry cycle

While receiving a growing attention in recent years, natural fibers cannot completely replace synthetic fibers as composite reinforcement for structural applications due to both their low durability in wet or humid environments and their limited and not homogenous overall performance. In this context, the purpose of this paper is to assess the impact of a humid/dry cycle on the mechanical stability of epoxy-based laminates reinforced with flax and glass fibers by using a topological weakening and softening map as simplified tool. The objective is, preliminarily, to evaluate the influence of glass fiber hybridization on the properties recovery of flax fiber reinforced composites subjected to alternate salt-fog/dry cycle. All laminates studied were subjected to salt spray for 15 or 30 days, and then stored in a dry controlled environment (50% relative humidity and 22 °C) for up to 21 days. The results evidenced that, compared to flax fiber reinforced composites, the glass hybridization of flax composite significantly reduce the mechanical performances degradation over time during the humid stage (about 28.0% better than flax one in stiffness). Furthermore, the mechanical performance recovery is promoted during the dry stage. A simplified topological map was lastly developed to graphically assess the decline and recovery of composites’ performances during the humid/dry cycle, amplifying the application and design effects of this approach

Effect of repeated salt fog-dry cycles on the performances reversibility of flax fiber reinforced composites

This paper aims to evaluate the effectiveness of flax fiber reinforced epoxy composites (FFRCs) under realistic environmental conditions, contributing to the development of sustainable composite materials for semi-structural outdoor applications. For this purpose, the reversibility of FFRC performance under consecutive and repeated humid-dry aging cycles was investigated for the first time. In particular, FFRCs were exposed to three cycles (total aging time of 12 weeks), with each cycle (duration 4 weeks) comprising 10 days of wetting (salt-fog spray; 35 °C, 95 % RH, 5 wt% NaCl solution) and 18 days of drying (22 °C, 50 % RH). Three-point bending tests were carried out up to 18 days of drying within each cycle to monitor changes in the mechanical performances of composites. Water absorption capacity, density and void content were also assessed by tracking weight changes throughout the aging campaign. The experimental results highlighted that the humid phase of each cycle causes degradation of FFRC materials, even though they are able to fully recover their flexural strength during each dry phase, indicating reversible aging. On the other hand, a stiffness permanent reduction was observed due to irreversible degradation phenomena

Adsorption performance and thermodynamic analysis of SAPO-34 silicone composite foams for adsorption heat pump applications

Abstract In the present work, adsorption performances of an innovative composite adsorber, based on SAPO-34-silicone composite macro-cellular foams, are reported. The choice of a foamed structure was assessed to improve the water vapor access towards the embedded zeolite keeping good adsorption heat pump dynamic performance. Depending on zeolite amount used as filler, zeolite/silicone foams evidenced a soft and open cell configuration (low zeolite content) or rigid and closed one (high zeolite content). Morphological analysis evidenced that the cellular structure of the foam is homogeneous and well distributed along the foam cross section. Adsorption tests showed that the adsorbent foamed samples have very effective adsorption capabilities indicating that the porous structure of the filled pure zeolite was not obstructed. SAPO-34 filler contributed actively, with an efficiency above 90%, to the adsorption performances of the composite foam. Starting from experimental equilibrium data, a simple thermodynamic analysis based on energy balances was carried out for air conditioning application. Results of the analysis demonstrated that foam technology can guarantee cooling COP up to 7% higher than that estimated for the typical adsorber solution based on loose adsorbent grains inside an aluminum finned-flat tube heat exchanger, which is very promising for practical application in adsorption heat pumps

In situ monitoring of moisture uptake of flax fiber reinforced composites under humid/dry conditions

The use of green materials such as natural fiber-reinforced composites represents an increasingly stringent prerogative in the future planning of industrial and non-industrial production. The optimization of these materials is the main aim of the current research, focused on the evaluation of the behavior of flax fiber reinforced composites exposed to isothermal adsorption and desorption cycles, at varying the partial pressure of water vapor (P/P0). For this purpose, the moisture uptake and the morphology changes of the composite material and their constituents were in situ monitored through a measurement protocol, by using a dynamic vapor sorption (DVS) analysis, coupled with an environmental scanning electron microscopy (ESEM) visual investigation. A dependence of moisture uptake and diffusivity on the composite morphology was clearly detected. In particular, no significant variation in the morphology of the specimen is noticed at low water vapor partial pressure (i.e., P/P0 up to 5.4%) due to the limited absorption capacity (i.e., lower than 1%). On the other hand, fibers morphology changes at increasing the partial pressure up to 25.1%, showing a sensitive increase in volume. This phenomenon becomes much more relevant for high relative humidity values (i.e., ~90%), reaching more than 6% of absorption capacity

Dynamical SPQEIR model assesses the effectiveness of non-pharmaceutical interventions against COVID-19 epidemic outbreaks.

Against the current COVID-19 pandemic, governments worldwide have devised a variety of non-pharmaceutical interventions to mitigate it. However, it is generally difficult to estimate the joint impact of different control strategies. In this paper, we tackle this question with an extended epidemic SEIR model, informed by a socio-political classification of different interventions. First, we inquire the conceptual effect of mitigation parameters on the infection curve. Then, we illustrate the potential of our model to reproduce and explain empirical data from a number of countries, to perform cross-country comparisons. This gives information on the best synergies of interventions to control epidemic outbreaks while minimising impact on socio-economic needs. For instance, our results suggest that, while rapid and strong lockdown is an effective pandemic mitigation measure, a combination of social distancing and early contact tracing can achieve similar mitigation synergistically, while keeping lower isolation rates. This quantitative understanding can support the establishment of mid- and long-term interventions, to prepare containment strategies against further outbreaks. This paper also provides an online tool that allows researchers and decision makers to interactively simulate diverse scenarios with our model