710 research outputs found
Integration of optical and passive microwave satellite data for flooded area detection and monitoring
Flooding represents a serious threat to millions of people around the world and its hazard is rising as a result of climate changes. From this perspective, flood risk management is a key focus of many governments, whose priority is to have frequently updated and accurate information about the flood state and evolution to promptly react to the disaster and to put in place effective countermeasures devoted to limit damages and human lives losses. Remote sensing technology allows for flood monitoring at different spatial and temporal resolutions with an adequate level of accuracy. In particular, for emergency response purposes, an integrated use of satellite data, acquired by both optical and passive or active microwave instruments, has to be preferred to have more complete and frequently updated information on soil conditions and to better support decision makers. In this framework, multi-year time series of MODIS (Moderate Resolution Imaging Spectroradiometer) and AMSR-E (Advanced Microwave Scanning Radiometer for Earth Observing System) data were processed and analyzed. In detail, the Robust Satellite Techniques (RST), a multi-sensor approach for satellite data analysis, has been implemented for studying the August 2002 Elbe river flood occurred in Germany, trying to assess the potential of such an integrated system for the determination of soil status and conditions (i.e. moisture variation, water presence) as well as for a timely detection and a near real time monitoring of critical soil conditions
Volcanic ash cloud detection from space: a preliminary comparison between RST approach and water vapour corrected BTD procedure
Volcanic eruptions can inject large amounts (Tg) of gas and particles into the troposphere and, sometimes, into
the stratosphere. Besides the main gases (H2O, CO2 , SO2 and HCl), volcanic clouds contain a mix of silicate
ash particles in the size range 0.1μm to mm or larger. Interest in the ash presence detection is high in particular
because it represents a serious hazard for air traffic. Particles with dimension of several millimeters can damage
the aircraft structure (windows, wings, ailerons), while particles less than 10μm may be extremely dangerous for
the jet engines and are undetectable by the pilots during night or in low visibility conditions.
Satellite data are useful for measuring volcanic clouds because of the large vertical range of these emissions and
their likely large horizontal spread. Moreover, since volcanoes are globally distributed and inherently dangerous,
satellite measurements offer a practical and safe platform from which to make observations. Two different
techniques used to detect volcanic clouds from satellite data are considered here for a preliminary comparison,
with possible implications on quantitative retrievals of plume parameters. In particular, the Robust Satellite
Techniques (RST) approach and a water vapour corrected version of the Brightness Temperature Difference
(BTD) procedure, will be compared.
The RST approach is based on the multi-temporal analysis of historical, long-term satellite records, devoted to a
former characterization of the measured signal, in terms of expected value and natural variability and a further
recognition of signal anomalies by an automatic, unsupervised change detection step. The BTD method is based
on the difference between the brightness temperature measured in two channels centered around 11 and 12 mm.
To take into account the atmospheric water vapour differential absorption in the 11–12 μm spectral range that
tends to reduce (and in some cases completely mask) the BTD signal, a water vapor correction procedure, based
on measured or synthetic atmospheric profiles, has been applied. Results independently achieved by both methods
during recent Mt. Etna eruptions are presented, compared and discussed also in terms of further implications for
quantitative retrievals of plume parameters
Exact Solution of the Discrete (1+1)-dimensional RSOS Model with Field and Surface Interactions
We present the solution of a linear Restricted Solid--on--Solid (RSOS) model
in a field. Aside from the origins of this model in the context of describing
the phase boundary in a magnet, interest also comes from more recent work on
the steady state of non-equilibrium models of molecular motors. While similar
to a previously solved (non-restricted) SOS model in its physical behaviour,
mathematically the solution is more complex. Involving basic hypergeometric
functions , it introduces a new form of solution to the lexicon of
directed lattice path generating functions.Comment: 10 pages, 2 figure
Toward the estimation of river discharge variations using MODIS data in ungauged basins
This study investigates the capability of the Moderate resolution Imaging Spectroradiometer (MODIS) to estimate river discharge, even for ungauged sites. Because of its frequent revisits (as little as every 3 h) and adequate spatial resolution (250 m), MODIS bands 1 and 2 have significant potential for mapping the extent of flooded areas and estimating river discharge even for medium-sized basins. Specifically, the different behaviour of water and land in the Near Infrared (NIR) portion of the electromagnetic spectrum is exploited by computing the ratio (C/M) of the MODIS channel 2 reflectance values between two pixels located within (M) and outside (C), but close to, the river. The values of C/M increase with the presence of water and, hence, with discharge. Moreover, in order to reduce the noise effects due to atmospheric contribution, an exponential smoothing filter is applied, thus obtaining C/M⁎.
Time series of hourly mean flow velocity and discharge between 2005 and 2011 measured at four gauging stations located along the Po river (Northern Italy) are employed for testing the capability of C/M⁎ to estimate discharge/flow velocity. Specifically, the meanders and urban areas are considered the best locations for the position of the pixels M and C, respectively. Considering the optimal pixels, the agreement between C/M⁎ and discharge/flow velocity is fairly good with values in the range of 0.65–0.77. Additionally, the application to ungauged sites is tested by deriving a unique regional relationship between C/M⁎ and flow velocity valid for the whole Po river and providing only a slight deterioration of the performance. Finally, the sensitivity of the results to the selection of the C and M pixels is investigated by randomly changing their location. Also in this case, the agreement with in situ observations of velocity is fairly satisfactory (r ~ 0.6). The obtained results demonstrate the capability of MODIS to monitor discharge (and flow velocity). Therefore, its application for a larger number of sites worldwide will be the object of future studies
Anodic behaviour of carbon steel bars in realkalised concrete: potentiodynamic and potentiostatic tests in solution
Electrochemical realkalisation is a technique used for the repair of reinforced concrete structures sufferingcarbonation-induced corrosion. It aims at restoring high levels of pH through the application of a temporarycathodic current. Although this technique was introduced in the 1980s and has been used since then, there arestill some aspects connected with its application that need investigation. In particular, it is not clear whether theusual techniques for measuring the corrosion activity of steel after the treatment can be considered reliable.This paper presents an experimental study on the anodic potentiodynamic and potentiostatic behaviour of steelin solutions simulating realkalised concrete and, for comparison, in solutions simulating alkaline and carbonatedconcrete. Results showed that in the alkaline solution used in the treatment steel bars are characterised bypassivity, in spite of the high values of corrosion rate measured with linear polarisation technique
Discovery of benzo[g]indol-3-carboxylates as potent inhibitors of microsomal prostaglandin E(2) synthase-1.
Selective inhibition of pro-inflammatory prostaglandin (PG)E2 formation via microsomal PGE2 synthase-1 (mPGES-1) might be superior over inhibition of all cyclooxygenase (COX)-derived products by non-steroidal anti-inflammatory drugs (NSAIDs) and coxibs. We recently showed that benzo[g]indol-3-carboxylates potently suppress leukotriene biosynthesis by inhibiting 5-lipoxygenase. Here, we describe the discovery of benzo[g]indol-3-carboxylates as a novel class of potent mPGES-1 inhibitors (IC50 ≥ 0.1 μM). Ethyl 2-(3-chlorobenzyl)-5-hydroxy-1H-benzo[g]indole-3-carboxylate (compound 7a) inhibits human mPGES-1 in a cell-free assay (IC50 = 0.6 μM) as well as in intact A549 cells (IC50 = 2 μM), and suppressed PGE2 pleural levels in rat carrageenan-induced pleurisy. Inhibition of cellular COX-1/2 activity was significantly less pronounced. Compound 7a significantly reduced inflammatory reactions in the carrageenan-induced mouse paw edema and rat pleurisy. Together, based on the select and potent inhibition of mPGES-1 and 5-lipoxygenase, benzo[g]indol-3-carboxylates possess potential as novel anti-inflammatory drugs with a valuable pharmacological profile
Validation of ash/dust detections from SEVIRI data using ACTRIS/EARLINET ground-based LIDAR measurements
Twotailored configurations of the Robust Satellite Technique (RST) multi-temporal approach, for airborne volcanic ash and desert dust detection, have been tested in the framework of the European Natural Airborne Disaster Information and Coordination System for Aviation (EUNADICS-AV) project. The two algorithms, running on Spinning Enhanced Visible Infra-Red Imager (SEVIRI) data, were previously assessed over wide areas by comparison with independent satellite-based aerosol products. In this study, we present results of a first validation analysis of the above mentioned satellite-based ash/dust products using independent, ground-based observations coming from the European Aerosol Research Lidar Network (EARLINET). The aim is to assess the capabilities of RST-based ash/dust products in providing useful information even at local scale and to verify their applicability as a "trigger" to timely activate EARLINET measurements during airborne hazards. The intense Saharan dust event of May 18-23 2008-which affected both the Mediterranean Basin and Continental Europe-and the strong explosive eruptions of Eyjafjallajökull (Iceland) volcano of April-May 2010, were analyzed as test cases. Our results show that both RST-based algorithms were capable of providing reliable information about the investigated phenomena at specific sites of interest, successfully detecting airborne ash/dust in different geographic regions using both nighttime and daytime SEVIRI data. However, the validation analysis also demonstrates that ash/dust layers remain undetected by satellite in the presence of overlying meteorological clouds and when they are tenuous (i.e., with an integrated backscatter coefficient less than ~0.001 sr-1 and with aerosol backscatter coefficient less than ~1 × 10-6 m-1sr-1). This preliminary analysis confirms that the continuity of satellite-based observations can be used to timely "trigger" ground-based LIDAR measurements in case of airborne hazard events. Finally, this work confirms that advanced satellite-based detection schemes may provide a relevant contribution to the monitoring of ash/dust phenomena and that the synergistic use of (satellite-based) large scale, continuous and timely records with (ground-based) accurate and quantitative measurements may represent an added value, especially in operational scenarios
Higher Muscle Mass Implies Increased Free-Thyroxine to Free-Triiodothyronine Ratio in Subjects With Overweight and Obesity
Thyroid hormones control both metabolic pathways and body composition, whereas little knowledge is available about the possible influence of skeletal muscle mass (MM) on thyroid hormone metabolism and circulating levels. This was a cross-sectional study conducted at the Population Health Unit of the National Institute of Gastroenterology IRCCS “S. de Bellis” (Italy) and investigating the extent to which skeletal MM affects thyroid function in obesity. Two hundred twenty-seven consecutive healthy volunteers (155 women and 72 men) with overweight and obesity (BMI ≥ 25 kg/m2) and taking no medication or supplement were assessed for hormone, metabolic and routine laboratory parameters. Body composition parameters were collected by using bioelectrical impedance analysis (BIA). MM was directly related to the body mass index (BMI), waist circumference (WC), insulin, triglycerides, uric acid and free-triiodothyronine (FT3) serum levels, FT3 to the free-thyroxine (FT4) ratio, and insulin-resistance (HOMA-IR), and inversely related to age, total, and HDL-cholesterol serum levels. Multiple regression models confirmed the relationship between MM and the FT3 to FT4 ratio, independently of age, BMI, TSH, triglycerides, and insulin serum levels. The same analyses run by gender showed that this relationship maintained significance only in men. Increased skeletal MM in obesity results in improved thyroid activity mediated by increased T4 conversion to T3, and higher FT3 circulating levels, particularly in men. In conclusion, preserving a greater skeletal MM in obesity helps to enhance thyroid activity. Clinical Trial Registration: ClinicalTrials.gov, identifier NCT04327375
A study on the Abruzzo 6 April 2009 earthquake by applying the RST approach to 15 years of AVHRR TIR observations
A self adaptive approach (RST, Robust Satellite Technique) has been proposed as a suitable tool for satellite TIR surveys in seismically active regions devoted to detect and monitor thermal anomalies possibly related to earthquake occurrence. In this work, RST approach has been applied to 15 years of AVHRR (Advanced Very High Resolution Radiometer) thermal infrared observations in order to study the 6 April 2009 Abruzzo earthquake. Preliminary results show clear differences in TIR anomalies occurrence during the periods used for validation (15 March–15 April 2009) and the one (15 March–15 April 2008) without earthquakes with <i>M</i><sub>L</sub>&ge;4.5, used for confutation purposes. Quite clear TIR anomalies appears also to mark main tectonic lineaments during the preparatory phases of others, low magnitude(3.9<<i>M</i><sub>L</sub><4.6) earthquakes, occurred in the area in the same period
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