A synergic integration of Synthetic Aperture Radar (SAR) and optical time series offers an unprecedented opportunity in vegetation phenology monitoring for mountain agriculture management. In this ...paper, we performed a correlation analysis of radar signal to vegetation and soil conditions by using a time series of Sentinel-1 C-band dual-polarized (VV and VH) SAR images acquired in the South Tyrol region (Italy) from October 2014 to September 2016. Together with Sentinel-1 images, we exploited corresponding Sentinel-2 images and ground measurements. Results show that Sentinel-1 cross-polarized VH backscattering coefficients have a strong vegetation contribution and are well correlated with the Normalized Difference Vegetation Index (NDVI) values retrieved from optical sensors, thus allowing the extraction of meadow phenological phases. Particularly for the Start Of Season (SOS) at low altitudes, the mean difference in days between Sentinel-1 and ground sensors is compatible with the acquisition time of the SAR sensor. However, the results show a decrease in accuracy with increasing altitude. The same trend is observed for senescence. The main outcomes of our investigations in terms of inter-satellite comparison show that Sentinel-1 is less effective than Sentinel-2 in detecting the SOS. At the same time, Sentinel-1 is as robust as Sentinel-2 in defining mowing events. Our study shows that SAR-Optical data integration is a promising approach for phenology detection in mountain regions.
Light field cameras capture the 3D information in a scene with a single exposure. This special feature makes light field cameras very appealing for a variety of applications: from post-capture ...refocus to depth estimation and image-based rendering. However, light field cameras suffer by design from strong limitations in their spatial resolution. Off-the-shelf super-resolution algorithms are not ideal for light field data, as they do not consider its structure. On the other hand, the few super-resolution algorithms explicitly tailored for light field data exhibit significant limitations, such as the need to carry out a costly disparity estimation procedure with sub-pixel precision. We propose a new light field super-resolution algorithm meant to address these limitations. We use the complementary information in the different light field views to augment the spatial resolution of the whole light field at once. In particular, we show that coupling the multi-view approach with a graph-based regularizer, which enforces the light field geometric structure, permits to avoid the need of a precise and costly disparity estimation step. Extensive experiments show that the new algorithm compares favorably to the state-of-the-art methods for light field super-resolution, both in terms of visual quality and in terms of reconstruction error.
During the last forty years, the use of strontium isotopes in archaeology and biogeochemical research has spread widely. These isotopes, alone or in combination with others, can contribute to trace ...past and present environmental conditions. However, the interpretation of the isotopic values of strontium is not always simple and requires good knowledge of geochemistry and geology. This short paper on the use of strontium isotopes is aimed at those who use this tool (archaeologists, but not only) but who do not have a thorough knowledge of mineralogy, geology, and geochemistry necessary for a good understanding of natural processes involving these isotopes. We report basic knowledge and suggestions for the correct use of these isotopes. The isotopic characteristics of bio-assimilable strontium depend not so much on the isotopic characteristics of the bulk rock as, rather, on those of its more soluble minerals. Before studying human, animal and plant remains, the state of conservation and any conditions of isotopic pollution should be carefully checked. Samples should be collected according to random sampling rules. The data should be treated by a statistical approach. To make comparisons between different areas, it should be borne in mind that the study of current soils can be misleading since the mineralogical modification of soil over time can be very rapid.
Grasslands cover up to 40% of the mountain areas globally and 23% of the European Alps and affect numerous key ecological processes. An increasing number of optical sensors offer a great opportunity ...to monitor and address dynamic changes in the growth and status of grassland vegetation due to climatic and anthropogenic influences. Vegetation indices (VI) calculated from optical sensor data are a powerful tool in analyzing vegetation dynamics. However, different sensors have their own characteristics, advantages, and challenges in monitoring vegetation over space and time that require special attention when compared to or combined with each other. We used the Normalized Difference Vegetation Index (NDVI) derived from handheld spectrometers, station-based Spectral Reflectance Sensors (SRS), and Phenocams as well as the spaceborne Sentinel-2 Multispectral Instrument (MSI) for assessing growth and dynamic changes in four alpine meadows. We analyzed the similarity of the NDVI on diverse spatial scales and to what extent grassland dynamics of alpine meadows can be detected. We found that NDVI across all sensors traces the growing phases of the vegetation although we experienced a notable variability in NDVI signals among sensors and differences among the sites and plots. We noticed differences in signal saturation, sensor specific offsets, and in the detectability of short-term events. These NDVI inconsistencies depended on sensor-specific spatial and spectral resolutions and acquisition geometries, as well as on grassland management activities and vegetation growth during the year. We demonstrated that the combination of multiple-sensors enhanced the possibility for detecting short-term dynamic changes throughout the year for each of the stations. The presented findings are relevant for building and evaluating a combined sensor approach for consistent vegetation monitoring.
Oxygen and carbon isotopes of well-preserved skeletal remains give relevant support to archaeological and environmental reconstructions. However, the preservation of the skeletal remains must be ...preliminarily checked. About twenty-five years ago, a diagnostic method based on the oxygen isotope ratio in the phosphate, δ(O18/O16)Ph, and carbonate, δ(O18/O16)Carb, of bioapatite of modern mammals was proposed: for well-preserved samples, the δ(O18/O16)Ph and δ(O18/O16)Carb should plot near the regression line δ(O18/O16)Ph on δ(O18/O16)Carb obtained for modern mammals. In the last twenty years, techniques of analysis have changed. In the past, BiPO4 or Ag3PO4 were precipitated from dissolved bioapatite and analysed with the fluorination technique, whereas at present, temperature reduction (HTR) in a glassy carbon reactor with CO release is commonly used. Taking into account the HTR technique, for some modern mammals, we report a new δ(O18/O16)Ph + 1 on δ(O18/O16)Carb + 1 regression line, and related dispersion of the data that, in addition to mineralogical and structural methods, may be used to select samples reliable for archaeological use. In the past, other similar regression lines on modern mammals were defined by several authors. However, statistical results indicate that data used for these regression lines cannot be pooled because the hypothesis of a similar elevation is rejected.
At present, the isotope ratio 18O/16O (in the text expressed as δ18O) of carbonate (CO32−) is usually determined by isotope ratio mass spectrometry measuring the CO2 gas produced dissolving the ...CO32−-bearing substance in concentrated H3PO4. As with any analytical data, the δ18O values of carbonate are also affected by uncertainty which must be considered mainly when data from different laboratories are compared. Usually, scientific papers report only repeatability and/or reproducibility of analytical results, which, have scarce significance for data comparison. With the aim of evaluating the overall uncertainty for new analytical data for low-Mg calcites, in this paper we reconsidered the δ18O data, which are reported in the literature. Two kinds of uncertainty must be taken into account: (1) that due to the calibration of the delta values using international standards (prediction uncertainty), (2) that due to small differences in the chemistry of low-Mg calcites. The two uncertainties must be added when comparing data produced in the same or different laboratories. We found that this overall uncertainty cannot be lower than about 0.2‰. Thus, uncertainty lower than 0.2‰, sometimes reported in the literature, is misleading.
Climate change is leading to advanced snowmelt date in alpine regions. Consequently, alpine plant species and ecosystems experience substantial changes due to prolonged phenological seasons, while ...the responses, mechanisms and implications remain widely unclear. In this 3‐year study, we investigated the effects of advancing snowmelt on the phenology of alpine snowbed species. We related microclimatic drivers to species and ecosystem phenology using in situ monitoring and phenocams. We further used predictive modelling to determine whether early snowmelt sites could be used as sentinels for future conditions. Temperature during the snow‐free period primarily influenced flowering phenology, followed by snowmelt timing. Salix herbacea and Gnaphalium supinum showed the most opportunistic phenology, while annual Euphrasia minima struggled to complete its phenology in short growing seasons. Phenological responses varied more between years than sites, indicating potential local long‐term adaptations and suggesting these species' potential to track future earlier melting dates. Phenocams captured ecosystem‐level phenology (start, peak and end of phenological season) but failed to explain species‐level variance. Our findings highlight species‐specific responses to advancing snowmelt, with snowbed species responding highly opportunistically to changes in snowmelt timings while following species‐specific developmental programs. While species from surrounding grasslands may benefit from extended growing seasons, snowbed species may become outcompeted due to internal‐clock‐driven, non‐opportunistic senescence, despite displaying a high level of phenological plasticity.
Our study investigates the phenological responses of five typical snowbed species to advancing snowmelt using in situ monitoring, phenocam imagery and predictive modelling. Over 3 years, we found temperature to be the primary driver of phenological changes in alpine snowbeds, with varying importance of photoperiodism among species. Results suggest a potential diminishing relevance of photoperiodism in warmer conditions.
In recent years, scientific research has increasingly focused on the cardiovascular benefits of omega-3 polyunsaturated fatty acids (n-3 PUFAs) supplements. The most promising results emerged from ...the new trials on a high-dose eicosapentaenoic acid (EPA)-only approach, instead of the previously prescribed therapy with EPA + docosahexaenoic acid (DHA). The evidence of the reduction of cardiovascular events in patients at high cardiovascular risk with EPA is intriguing. However, physicians have expressed concern about the potential high risk of atrial fibrillation (AF) occurrence due to such an approach. This study aims to investigate the current evidence on the cardiovascular benefits of EPA and its association with atrial arrhythmogenesis. Current guidelines consider EPA (as IPE) treatment for selected patients but with no specific indication regarding AF risk evaluation. We propose a flowchart that could be a starting point for the future development of an algorithm to help clinicians to prescribe EPA safely and effectively, especially in patients at high risk of incipient AF.
•AUT/AU and AUT/AU bi-dimensional electrophoresis efficiently separates brain proteins.•Cofilin 1 is dynamically regulated in the mouse visual cortex.•Cofilin 1 is a candidate in the control of ...visual cortex plasticity.
In order to characterize the mechanisms controlling plasticity in the mouse visual cortex, we used, for the first time on brain samples, an unconventional proteomic approach to separate acid-extracted proteins by bi-dimensional electrophoresis (AUT/SDS or AUT/AU gels). The analysis was performed on high plasticity critical period young vs. low plasticity adult, and on fluoxetine-induced high plasticity vs. low plasticity untreated adult mice. Mass spectrometry allowed for the identification of 11 proteins that are differentially expressed between critical period and adult mice, and 5 between fluoxetine-treated and control adult mice. We then focused on cofilin 1, as the intensity level of the corresponding spot on 2D gels was higher in both high plasticity conditions. Western blot showed that cofilin 1 expression is dynamically regulated during postnatal life, reaching a peak at the critical period, and decreasing at adult stage, and that it increases in fluoxetine-treated vs. untreated adult mice. In summary, by using a 2D gel electrophoresis differential approach on basic proteins followed by mass spectrometry and immunoblot analysis, we identified cofilin 1 as a potential candidate controlling plasticity levels of the mouse visual cortex.
This paper proposes a model-based two-degree-of-freedom (2DOF) speed control for a medium voltage (MV) variable speed drive (VSD) connected to a centrifugal compressor (CC) train. Torsional mode ...excitations in the drive shaft due to converter switching behaviour are considered. An effective description of the harmonics transfer is proposed. The tuning strategy aims to optimize the tracking behaviour of the step and ramp command, taking care of critical speed excitations. The stability of the closed-loop dynamics against time delay and drive parameter variations are studied by means of Nyquist diagrams and time-domain simulations. A descriptive method for the process damping behaviour is proposed. The control strategy is evaluated through simulations as well as an experimental setup, based on a hardware in the loop (HIL) in a master–slave configuration.
PDF
