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6 figures, 2 tables.-- Data availability statement: No new data were created or analysed in this study, Nowadays, there is a growing awareness on the social and economic importance of the ocean. In this context, being able to carry out a diverse range of operations underwater is of paramount importance for many industrial sectors as well as for marine science and to enforce restoration and mitigation actions. Underwater robots allowed us to venture deeper and for longer time into the remote and hostile marine environment. However, traditional design concepts such as propeller driven remotely operated vehicles, autonomous underwater vehicles, or tracked benthic crawlers, present intrinsic limitations, especially when a close interaction with the environment is required. An increasing number of researchers are proposing legged robots as a bioinspired alternative to traditional designs, capable of yielding versatile multi-terrain locomotion, high stability, and low environmental disturbance. In this work, we aim at presenting the new field of underwater legged robotics in an organic way, discussing the prototypes in the state-of-the-art and highlighting technological and scientific challenges for the future. First, we will briefly recap the latest developments in traditional underwater robotics from which several technological solutions can be adapted, and on which the benchmarking of this new field should be set. Second, we will the retrace the evolution of terrestrial legged robotics, pinpointing the main achievements of the field. Third, we will report a complete state of the art on underwater legged robots focusing on the innovations with respect to the interaction with the environment, sensing and actuation, modelling and control, and autonomy and navigation. Finally, we will thoroughly discuss the reviewed literature by comparing traditional and legged underwater robots, highlighting interesting research opportunities, and presenting use case scenarios derived from marine science applications, With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) is currently operating, providing information of the subsurface structure of the planet Mars. The transmitted chirp signals pass through the ionosphere, resulting delayed, attenuated, and, in the phase, distorted. MARSIS signals are routinely phase corrected during ground processing by adopting a predefined model based on the Chapman theory. In this letter, phase distortions are compensated by using a phase-gradient-autofocus algorithm, which is capable of correcting distortions of different nature by exploiting their redundancy along the orbit. For the first time, images presenting saturated regions have been recovered.

We describe a method to estimate the total electron content (TEC) of the Mars ionosphere from the output parameters of an algorithm, called the Contrast Method (Picardi, G., Sorge, S. [2000]. Proc. SPIE. Eighth International Conference on Ground Penetrating Radar, vol. 4084, pp. 624–629; Ilyushin, Ya.A., Kunitsyn, V.E. [2004]. J. Commun. Technol. Electron. 49, 154–165), which allows to correct the phase distortion of the echoes recorded by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) (Picardi, G. et al. [2005]. Science 310, 1925–1928) in its subsurface mode. Based on the TEC values evaluated during 6 years of MARSIS activity, corresponding to about 4600 orbits, in this paper we present a global map of the night side TEC variations, which correlates well with the magnetic field model derived from Mars Global Surveyor (MGS) Magnetometer/Electron Reflectometer (MAG/ER) data. In particular, we demonstrate that regions of enhanced TEC preferentially correspond to areas where crustal magnetic field lines are quasi perpendicular to the martian surface; moreover, we demonstrate that, in regions where the magnetic field is predominantly nearly vertical, enhanced TEC values correlate with higher field intensities, while in regions where the magnetic field is predominantly nearly horizontal, such correlation is not observed. As already suggested in the past by other authors, we suggest that increased TEC values may be related to the precipitation of electrons from the martian magnetospheric tail along vertical crustal magnetic field lines.

Objective: Data on the incidence of new onset atrial fibrillation and flutter (AF/f) in patients with acute pericarditis are limited. We sought to determine the incidence and prognostic significance of AF/f in this setting. Methods: Between January 2006 and June 2014, consecutive new cases of acute pericarditis were included in two urban referral centres for pericardial diseases. All new cases of AF/f defined as episodes lasting ≥30 s were recorded. Events considered during follow-up consisted of AF/f and pericarditis recurrence, cardiac tamponade, pericardial constriction and death. Results:822 consecutive new cases of acute pericarditis (mean age 53±15 years, 444 men) were analysed. AF/f was detected in 35 patients (4.3%, mean age 66.5±11.3 years, 18 men). Patients with AF/f were significantly older (p=0.017) and presented more frequently with pericardial effusion (p24 h in 25.7% and spontaneously converted in 74.3% of patients. Underlying structural heart disease was present in 17% of AF/f cases. In a 30-month follow-up, patients with history of AF/f at the initial episode had a higher rate of arrhythmia occurrence (34.3% vs 0.9%, p

The Martian ionosphere has for the first time been probed by a low frequency topside radio wave sounder experiment (MARSIS) (Gurnett et al., 2005). The density profiles in the Martian ionosphere have for the first time been observed for solar zenith angles less than 48 degrees. The sounder spectrograms typically have a single trace of echoes, which are controlled by reflections from the ionosphere in the direction of nadir. With the local density at the spacecraft derived from the sounder measurements and using the lamination technique the spectrograms are inverted to electron density profiles. The measurements yield electron density profiles from the sub-solar region to past the terminator. The maximum density varies in time with the solar rotation period, indicating control of the densities by solar ionizing radiation. Electron density increases associated with solar flares were observed. The maximum electron density varies with solar zenith angle as predicted by theory. The altitude profile of electron densities between the maximum density and about 170 km altitude is well approximated by a classic Chapman layer. The neutral scale height is close to 10 to 13 km. At altitudes above 180 km the densities deviate from and are larger than inferred by the Chapman layer. At altitudes above the exobase the density decrease was approximated by an exponential function with scale heights between 24 and 65 km. The densities in the top side ionosphere above the exobase tends to be larger than the densities extrapolated from the Chapman layer fitted to the measurements at lower altitudes, implying more efficient upward diffusion above the collision dominated photo equilibrium region.

International audience; The martian subsurface has been probed to kilometer depths by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express orbiter. Signals penetrate the polar layered deposits, probably imaging the base of the deposits. Data from the northern lowlands of Chryse Planitia have revealed a shallowly buried quasi-circular structure about 250 kilometers in diameter that is interpreted to be an impact basin. In addition, a planar reflector associated with the basin structure may indicate the presence of a low-loss deposit that is more than 1 kilometer thick.

An analytical closed-form model is derived for the average power echo received by a bistatic altimeter from an oceanic surface at a frequency high enough for the Kirchhoff scattering mechanism to be dominant over the Bragg resonance one. The asymmetric behavior of the sea waves is taken into account, modeling the surface height as a non-Gaussian distributed random process and an explicit expression of the so-called "electromagnetic bias" is obtained as a function of the skewness coefficient of the distribution. Results obtained applying such model to a monostatic geometry are shown to be in good agreement with those reported in literature as well as with those obtained by numerical simulations. It is also shown that, letting the "non-Gaussianity" term tend to zero, our model correctly reduces to the well-known Brown model for Gaussian surfaces. This work has been conceived in the frame of the feasibility study of a bistatic remote sensing system, consisting of a constellation of satellites lying at the same altitude with an operating geometry such that the incidence and scattering angles are equal.

Rowing ergometers are used by athletes for indoor training and performance improvement. Typical commercial ergometers provide some information (for example power output and covered distance), but these indications are typically estimated starting from the fan speed and thus are not very reliable as already pointed out in the literature. The present paper presents the work done to fully instrument a commercial rowing ergometer in order to directly measure all relevant quantities for improved training: the seat, the handlebar and the stretchers have been redesigned and equipped with force and displacement sensors able to measure both the dynamic and kinematic behavior of the athlete. In this way the interaction of the athlete with the rowing machine is fully known, together with the direct measurement of the instantaneous rowing power output. Some results are also presented and discussed.

The Mars advanced radar for subsurface and ionospheric sounding (MARSIS) on Mars Express is the first high-frequency sounding radar operating from orbital altitudes since the Apollo 17 Lunar Sounder flown in 1972. The radar operates from a highly elliptical orbit but acquires data only from altitudes lower than 1200 km. The periapsis altitude is 250 km. This radar has been succesfully operating since August 2005. The radar is a dual channel low-frequency sounder, operates between 1.3 and 5.5 MHz (MegaHertz) with wavelengths between 230 and 55 m in free space for subsurface sounding and between 0.1 and 5.5 MHz (wavelengths between 3000 and 55 m) for ionospheric sounding. The subsurface sounder can operate at one or two-frequency bands out of four available bands at either like or cross polarization. The subsurface sounding radar transmits radio frequency (RF) pulses of 250 μs duration through a 40 m dipole antenna. The return echoes are then converted to digital form and temporarily stored on board for some digital processing. A second antenna, a monopole, provides reception for the cross-polarized return and its data are processed by a second channel. This processing reduces the data rate produced by the instrument to rates allowed by the spacecraft communications channel. These processed returns are then sent to Earth by the telecommunications system on the spacecraft. The advances in digital data acquisition and processing, since 1972, have enabled this technique to be used in a compact spacecraft science instrument.. This sounder has obtained returns from several kilometers below the surface of the Mars. The ionospheric sounder operates at altitudes greater than 800 km in a mode that sweeps the entire 0.1–5.5 MHz range. During ionospheric sounding, the transmitter sends a 91 μs tone at 127 pulses per second rate. The frequency sweep takes 7.3 s to complete the 0.1–5.5 MHz range. Operational aspects of the instrument are described, including the selection of frequency bands and receive antenna selection, which are based on the expected solar zenith angle. The process of data take planning as well as data archiving are described. Results of both subsurface and ionospheric sounding are presented.

The Martian ionosphere's local total electron content (TEC) and the neutral atmosphere scale height can be derived from radar echoes reflected from the surface of the planet. We report the global distribution of the TEC by analyzing more than 750,000 echoes of the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS). This is the first direct measurement of the TEC of the Martian ionosphere. The technique used in this paper is a novel 'transmission-mode' sounding of the ionosphere of Mars in contrast to the Active Ionospheric Sounding experiment (AIS) on MARSIS, which generally operates in the reflection mode. This technique yields a global map of the TEC for the Martian ionosphere. The radar transmits a wideband chirp signal that travels through the ionosphere before and after being reflected from the surface. The received waves are attenuated, delayed and dispersed, depending on the electron density in the column directly below the spacecraft. In the process of correcting the radar signal, we are able to estimate the TEC and its global distribution with an unprecedented resolution of about 0.1 deg in latitude (5 km footprint). The mapping of the relative geographical variations in the estimated nightside TEC data reveals an intricate web of high electron density regions that correspond to regions where crustal magnetic field lines are connected to the solar wind. Our data demonstrates that these regions are generally but not exclusively associated with areas that have magnetic field lines perpendicular to the surface of Mars. As a result, the global TEC map provides a high-resolution view of where the Martian crustal magnetic field is connected to the solar wind. We also provide an estimate of the neutral atmospheric scale height near the ionospheric peak and observe temporal fluctuations in peak electron density related to solar activity.

The spectral estimation of received signal is the most modern approach used in the radar to distinguish useful targets in clutter environment. In this paper we are analysed the clutter cancellation properties with three clutter models, so we think to have filled a great dynamics of practical conditions; the clutter estimation error is also evaluated in terms of improvement factor losses.

A new approach to the processing of radar altimeter data is studied in order to estimate characteristic parameters of the observed surface which are not given by conventional processing. The performance of an estimator based on the maximum likelihood principle is discussed. Given a suitable model of the surface echo and under some general hypotheses, the architecture and performance of both a monodimensional and a bidimensional estimator are worked out with respect to the theoretical Cramer-Rao bounds. >

The paper presents a processing technique to be applied to nadir looking radar sensors to gain altimetric data with high precision. Pulse limited altimeters are considered as those in use for the mapping of a surface. High resolution is obtained by means of phase monopulse in the cross-track direction while synthetic aperture processing followed by a proper incoherent technique is proposed for the resolution in the along-track direction.

Describes the experiment proposed for the remote sensing of the comet P/Wirtanen. To achieve the experiment objectives a multimode microwave sensor has been designed which accommodates three different modes of operation: radiometer mode, altimetry mode and sounder mode. A discussion of the leading concepts is presented on which the experiment is based.

A new-concept radar altimeter for the ESA-NASA joint mission named Rosetta has been studied. The goal of that mission is to approach and land on a comet nucleus, take a sample of the comet nucleus, and bring it to the Earth. The success of the mission is strongly related to a safe landing on a suitable site. A radar altimeter should perform the main operations during the landing phase giving information not only about attitude and surface roughness but also about the surface composition and the presence and nature of subsurface discontinuities. Surface composition means the type of material giving rise to the observed echo. A comet model, an EM model of the received echo, the radar altimeter operational mode, and optimum system design criteria are discussed in terms of transmitted frequency, pulse repetition frequency and signal bandwidth. >

Presents the radar sounding of comet nucleus layered surface for the Rosetta mission. The science objectives are the identification of the surface and subsurface layer material components and the depth measurement of the first layer, by using a two layered nucleus model. An in situ investigation by a light weight and low power consumption probe can be proposed; this is achieved by ground-radar pulse technology. Moreover, a wideband radar can be used by the orbiter: this solution leads also to the generation of the comet nucleus profile and surface images. The radar can also be used as a navigation aid. The aim of this paper is the definition of a electromagnetic (em) model of the cometary nucleus and the computation of the dielectric constants of the materials. The adopted hypothesis are the flatness and smoothness of the discontinuities: the electrical parameters of the regolith are variable only with depth. Using the measurement of the surface and subsurface reflectivities and of the time delay between the first and second received echo the nucleus parameters can be estimated by solving the "inverse problem".

MARSIS (Mars Advanced Radar for Subsurface Ionosphere Sounding), selected as scientific payload of the ESA mission Mars Express, is a low-frequency nadir-looking pulse limited radar sounder and altimeter with ground penetration capabilities, which uses synthetic aperture techniques and a secondary receiving antenna to isolate subsurface reflections. In order to maximize the penetration capabilities of the transmitted pulse MARSIS must operate at a frequency as low as possible (few MHz). Moreover the requirement for fine range resolution calls for a relatively large transmitted bandwidth (1 MHz) so that MARSIS will operate with a very high fractional bandwidth and very dose to the expected Martian ionosphere plasm frequency. This will result in a generally large phase distortion across the spectrum of the received pulses (due to either the antenna frequency response or the propagation through the ionosphere) which will cause severe degradation of the matched filter performance in term of SNR, pulse spreading and sidelobe level. This paper deals with the definition and implementation of an adaptive range compression algorithm, which makes use of the contrast maximization technique to estimate the phase dispersion spectrum, in order to perform a matched filtering of radar sounder echoes in the presence of phase distortions across the signal bandwidth.

For pulse-limited (PL) altimeters the spatial resolution is limited by the pulse width: the same concept is applicable to the bistatic altimeter. While the spacecraft (S/C) passes over the PL zone hundreds of looks can be acquired and non-coherently averaged to reduce the speckle noise. Typical PL altimeters average hundreds of looks obtaining height accuracy of few centimeters. PL altimeters are very well suited to open ocean applications, where wide stationary regions exist and the surface slopes on a large scale are nearly absent. As opposed, when encountering rougher surfaces, with prominent features and non zero slopes, such as land surfaces, coastal regions, ice sheets, etc. the poor spatial resolution inherent in the pulse limited approach becomes inadequate to the observed surface and the altimeter performance degrades severely. In order to overcome these problems the spatial resolution can be improved at least in the along track direction, by low-pass filtering the received echoes in the Doppler frequency domain. Instruments based on this concept have been called Doppler beam sharpened (DBS) altimeters and generally achieve this improvement in resolution at the expense of a reduction of the illuminated footprint size and thus of the non-coherent integration capability. Both these shortcomings can be overcome implementing a bank of parallel Doppler filters that span the whole illuminated footprint and using all the Doppler filters to observe each along track location. This is easily obtained in the Doppler radar altimeter (DRA).

PTX3 is a prototypic long pentraxin expressed by various cell types, most prominently monocytes and endothelial cells, in response to interleukin-1 (IL-1), tumor necrosis factor (TNF) and bacterial products. In the present report, we show that interferon-gamma (IFN-gamma) inhibits the expression of the PTX3 gene induced by exposure to IL-1, TNF or lipopolysaccharide in human monocytes. This effect is dose dependent and observable when IFN-gamma is added from 24 h before up to 3 h after the addition of IL-1. While the time course of the IL-1-induced PTX3 mRNA expression is not affected, IFN-gamma reduces the stability of the PTX3 mRNA as well as its transcription. The inhibition of PTX3 expression is restricted to monocytes in that no inhibition occurs in cytokine-stimulated fibroblasts and endothelial cells. Under the same conditions, as expected, IFN-gamma augmented monocyte chemotactic protein-1 expression in the same cell preparations. PTX3 protein secretion by activated monocytes is also suppressed by exposure to IFN-gamma. Altogether, these data identify a negative pathway of regulation mediated by IFN-gamma, which may occur under inflammatory conditions.

Doppler beam sharpened (DBS) radar altimeters use synthetic aperture techniques to improve the spatial resolution in the along track direction beyond the diameter of the pulse limited zone, yielding an instrument which overcomes most of the typical shortcomings that affect conventional satellite altimeters when facing surfaces more irregular than open oceans. In this paper the authors derive a generalized analytic model of the two dimensional (range/doppler) flat surface response of a DBS altimeter. The knowledge of such a function can be of great importance to derive unbiased estimators of the surface elevation at each along track position, capable to extending the multilook averaging over the whole time during which a surface element is illuminated by the antenna beam.

A nadir looking radar altimeter, capable to operate coherently in both along track and cross track directions by means of Doppler beam sharpening (DBS) and small baseline nadir interferometry techniques, has being studied as a candidate instrument for a small satellite lunar topographic mission, aimed to cover the whole lunar surface in less than one year from a circular polar orbit of 100-200 km. Performance calculations indicate that the resulting instrument should be able to extract the three-dimensional profile of the observed surface with medium horizontal resolution (few hundreds meters) and high vertical resolution (few meters).

Pentraxins, which include C reactive protein (CRP) and serum amyloid P component (SAP), are prototypic acute phase reactants that serve as indicators of inflammatory reactions. Here we report genomic and cDNA cloning of mouse ptx3 (mptx3), a member of the pentraxin gene family and characterize its extrahepatic expression in vitro and in vivo. mptx3 is organized into three exons on chromosome 3: the first (43 aa) and second exon (175 aa) code for the signal peptide and for a protein portion with no high similarity to known sequences the third (203 aa) for a domain related to classical pentraxins, which contains the "pentraxin family signature." Analysis of the N terminal portion predicts a predominantly alpha helical structure, while the pentraxin domain of ptx3 is accommodated comfortably in the tertiary structure fold of SAP. Normal and transformed fibroblasts, undifferentiated and differentiated myoblasts, normal endothelial cells, and mononuclear phagocytes express mptx3 mRNA and release the protein in vitro on exposure to interleukin-1beta (IL-1beta) and tumor necrosis factor (TNF)alpha. mptx3 was induced by bacterial lipopolysaccharide in vivo in a variety of organs and, most strongly, in the vascular endothelium of skeletal muscle and heart. Thus, mptx3 shows a distinct pattern of in vivo expression indicative of a significant role in cardiovascular and inflammatory pathology.

Among the scientific objectives defined in the frame of the INTERMARSNET International Mission is included the measurement of the surface dielectric constant on the whole Martian surface. For this purpose a radar/scatterometer system has been studied which is in principle able to provide information concerning backscattering coefficient averaged over the radar spatial resolution cell. As a secondary science objective the same instrument is also able to provide 3D mapping of the Martian surface with a coarse horizontal (or spatial) resolution and an accurate measure of the mean surface height and roughness (altimeter mode). Furthermore the use of a spinned satellite without an antenna stabilization in the mission results in a proper system design for the radar sensor.

Endothelial cells play an active role in several different inflammatory and immunological reactions which take place in the tissues.

Three main problem of high resolution spotlight SAR have been evaluated: constraints of system parameter on the swath which can be focused, the evaluation of various focusing algorithm to face the main problem of a limited Depth of Field for usual focusing algorithms, the relation between focusing algorithms and real time operation. Different algorithms are treated in a unifying theoretical way to make differences and similarities to appear evident, as their optimality relative to particular radar trajectory.

In 5 patients with frequent premature ventricular ectopic beats, refractory to other antiarrhythmic treatments, amiodarone, given orally at the dose of 200 mg once a day for 4 weeks, reduced beta-adrenoceptor density from 202.9 +/- 62 to 101.1 +/- 33 fmol/mg protein (p0.01). Similarly, kd decreased from 21.0 +/- 6 to 3.9 +/- 1 (p0.05). Changes in beta-adrenoceptor population were accompanied by a marked reduction in mean premature ventricular complexes (PVC) frequency from the control value of 428.9 +/- 150.3 to 13.4 +/- 10.7 PVC/h (p0.05) and by a decrease in heart rate, from 83.8 +/- 4 to 73.9 +/- 4 b/min (p0.01). On the contrary, mean arterial pressure remained unchanged. Patients did not show side effects during treatment. Therefore, low dose oral amiodarone has important pharmacologic and therapeutic effects. It significantly reduces lymphocyte beta-adrenoceptor density and is effective in treatment of ventricular arrhythmias. Additional studies were performed in vitro exposing lymphocytes to increasing concentrations of amiodarone. The analysis of variance for repeated measures showed that amiodarone-induced reduction in lymphocyte beta-adrenoceptor density is a dose-depending phenomenon. Accordingly, treatment with doses of amiodarone higher than that used in the present study may induce a major reduction in lymphocyte beta-receptor density and exert a depressant cardiac effect.

In order to detect subclinical levels of Doxorubicin (D) cardiotoxicity, 21 patients aged 42 +/- 8 years with malignancies and treated with D as a part of a multiple regimen, were evaluated. The mean cumulative dose of D was 242 +/- 112 mg.m-2 (150 to 520 mg.m-2). Patients with systemic hypertension, valvular diseases, suspected coronary artery disease, ejection fraction less than 55% as assessed by radionuclide angiography, and aged more than 50 years were excluded from the study. A Doppler echocardiographic examination was performed before and after the course of D therapy with a mean interval of 142 days. The following variables were assessed: fractional shortening (FS), ejection fraction (EF), stroke volume (SV), isovolumic relaxation time (IVRT), maximal early diastolic flow velocity (Emax), maximal late diastolic flow velocity (Amax), and mitral deceleration time (Mdt). Indices derived from 19 aged-matched normal subjects were compared to those of the patients before the course of therapy. Doppler echocardiographic measurements did not differ significantly between the control group and patients before the course of therapy. While there were no significant changes in FS, EF, and SV in the study group before and after therapy, indices of diastolic filling showed striking differences: IVRT changed from 72 +/- 11 to 87 +/- 19 ms (P less than 0.001), Emax from 81 +/- 12 to 65 +/- 17 cm.s-1 (P less than 0.001), Mdt from 174 +/- 25 to 183 +/- 34 ms (P less than 0.05), Amax from 44 +/- 17 to 52 +/- 16 cm.s-1 (P less than 0.01). These data demonstrate impaired diastolic filling after doxorubicin therapy at conventional dosages.

In order to detect subclinical levels of Doxorubicin (D) cardiotoxicity, 21 patients aged 42 ±8 years with malignancies and treated with D as a part of a multiple regimen, were evaluated. The mean cumulative dose of D was 242 ±112 mg.m−2 (150 to 520 mg.m−2). Patients with systemic hypertension, valvular diseases, suspected coronary artery disease, ejection fraction

In this paper a new computer aided ECG and VCG data handling is analized. It is based on an optimum estimation of dipole moment, which is used as the main diagnosis parameter. Already known diagnostical methods (available in present literature) are compared with this new technique. The available diagnostical range has been increased widely. The sensitivity of such a program is being analyzed both for normal and abnormal cases.

This paper deals with the techniques to derive an image of the internal permittivity of Comet Wirtanen (46P/Wirtanen) from the CONSERT experiment in ESA's Rosetta cometary mission. First, the theoretical limits of the inversion are explored for the present configuration of the experiment, showing there is some degree of ambiguity. Then, a possible variation of the experiment is proposed to essentially eliminate the ambiguity at the expense of an increased data rate and a new operating mode. Finally, inversion techniques are proposed both for the new and the old operating modes.