In situ remediation of contaminated marinesediment: an overview

Sediment tends to accumulate inorganic and persistent hydrophobic organic contaminants representing one of the main sinks and sources of pollution. Generally, contaminated sediment poses medium- and long-term risks to humans and ecosystem health; dredging activities or natural resuspension phenomena (i.e., strongly adverse weather conditions) can remobilize pollution releasing it into the water column. Thus, ex situ traditional remediation activities (i.e., dredging) can be hazardous compared to in situ techniques that try to keep to a minimum sediment mobilization, unless dredging is compulsory to reach a desired bathymetric level. We reviewed in situ physico-chemical (i.e., active mixing and thin capping, solidification/stabilization, chemical oxidation, dechlorination, electrokinetic separation, and sediment flushing) and bio-assisted treatments, including hybrid solutions (i.e., nanocomposite reactive capping, bioreactive capping, microbial electrochemical technologies). We found that significant gaps still remain into the knowledge about the application of in situ contaminated sediment remediation techniques from the technical and the practical viewpoint. Only activated carbon-based technologies are well developed and currently applied with several available case studies. The environmental implication of in situ remediation technologies was only shortly investigated on a long-term basis after its application, so it is not clear how they can really perform

The Earthlike Shoreline Morphology of Titan's Ontario Lacus

Ontario Lacus' shoreline features include Earth-like rivers, deltas and flooded topography. Ontario is a dynamic lake, similar in many ways to terrestrial lakes, with active shoreline processes

25 years of satellite InSAR monitoring of ground instability and coastal geohazards in the archaeological site of Capo Colonna, Italy

For centuries the promontory of Capo Colonna in Calabria region, southern Italy, experienced land subsidence and coastline retreat to an extent that the archaeological ruins of the ancient Greek sanctuary are currently under threat of cliff failure, toppling and irreversible loss. Gas extraction in nearby wells is a further anthropogenic element to account for at the regional scale. Exploiting an unprecedented satellite Synthetic Aperture Radar (SAR) time series including ERS-1/2, ENVISAT, TerraSAR-X, COSMO-SkyMed and Sentinel-1A data stacks acquired between 1992 and 2016, this paper presents the first and most complete Interferometric SAR (InSAR) baseline assessment of land subsidence and coastal processes affecting Capo Colonna. We analyse the regional displacement trends, the correlation between vertical displacements with gas extraction volumes, the impact on stability of the archaeological heritage, and the coastal geohazard susceptibility. In the last 25 years, the land has subsided uninterruptedly, with highest annual line-of-sight deformation rates ranging between -15 and -20 mm/year in 2011-2014. The installation of 40 pairs of corner reflectors along the northern coastline and within the archaeological park resulted in an improved imaging capability and higher density of measurement points. This proved to be beneficial for the ground stability assessment of recent archaeological excavations, in an area where field surveying in November 2015 highlighted new events of cliff failure. The conceptual model developed suggests that combining InSAR results, geomorphological assessments and inventorying of wave-storms will contribute to unveil the complexity of coastal geohazards in Capo Colonna. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Multiple translational products from a Mycoplasma hyorhinis gene expressed in Escherichia coli

We analyzed protein expression from a cloned Mycoplasma hyorhinis genomic fragment that produces in Escherichia coli a set of related polypeptides of 110, 100, 65, and 55 kilodaltons from a coding region of just over 3.0 kilobases. Expression of these multiple products resulted from a mechanism operating at the translational level but not from truncation at UGA termination codons, which are known to encode tryptophan in several mycoplasma species. The structural relatedness of the proteins was demonstrated by two-dimensional tryptic peptic mapping, but their generation by posttranslational processing was ruled out by pulse-chase labeling analysis. Examination of proteins expressed from plasmid constructs and tryptic peptide analysis of these polypeptides and the original set of proteins revealed that they share carboxy-terminal regions, an observation inconsistent with truncation at UGA codons. Expression of proteins from this cloned fragment was not dependent on vector sequences and was observed when the coding region was placed under control of a T7 promoter, suggesting that all products were translated from a single message. Expression of related products in mycoplasmas was examined by immunoblot analysis of M. hyorhinis proteins with antiserum against overexpressed recombinant proteins. A single 115-kilodalton mycoplasma protein was detected, which is larger than any of the related proteins expressed in E. coli. Our analysis indicated that translation initiation sites are used in E. coli that are not active in mycoplasmas, thereby defining differences between the translational regulatory signals of mycoplasmas and eubacteria.</jats:p

The Ketogenic Diet Improves Gut–Brain Axis in a Rat Model of Irritable Bowel Syndrome: Impact on 5-HT and BDNF Systems

Altered gut–brain communication can contribute to intestinal dysfunctions in the intestinal bowel syndrome. The neuroprotective high-fat, adequate-protein, low-carbohydrate ketogenic diet (KD) modulates the levels of different neurotransmitters and neurotrophins. The aim was to evaluate the effects of KD on levels of 5-HT, the receptors 5-HT3B and 5-HT4, the 5-HT transporter SERT, the neurotrophin BDNF, and its receptor TrkB in the colon and brain of a rat model of irritable bowel syndrome (IBS). Samples from Wistar rats exposed to maternal deprivation as newborns and then fed with a standard diet (IBS-Std) or KD (IBS-KD) for ten weeks were analyzed. As controls, unexposed rats (Ctrl-Std and Ctrl-KD) were studied. IBS-Std rats had a disordered enteric serotoninergic signaling shown by increased mucosal 5-HT content and reduced SERT, 5-HT3B, and 5-HT4 levels compared to controls. In the brain, these animals showed up-regulation of the BDNF receptor TrkB as a counteracting response to the stress-induced reduction of the neurotrophin. KD showed a dual effect in improving the altered 5-HT and BDNF systems. It down-regulated the increased mucosal 5-HT without affecting transporter and receptor levels. KD improved brain BDNF levels and established negative feedback, leading to a compensatory downregulation of TrkB to maintain a physiological steady state

Enhanced gradient tracking algorithms for distributed quadratic optimization via sparse gain design

In this paper we propose a new control-oriented design technique to enhance the algorithmic performance of the distributed gradient tracking algorithm. We focus on a scenario in which agents in a network aim to cooperatively minimize the sum of convex, quadratic cost functions depending on a common decision variable. By leveraging a recent system-theoretical reinterpretation of the considered algorithmic framework as a closed-loop linear dynamical system, the proposed approach generalizes the diagonal gain structure associated to the existing gradient tracking algorithms. Specifically, we look for closed-loop gain matrices that satisfy the sparsity constraints imposed by the network topology, without however being necessarily diagonal, as in existing gradient tracking schemes. We propose a novel procedure to compute stabilizing sparse gain matrices by solving a set of nonlinear matrix inequalities, based on the solution of a sequence of approximate linear versions of such inequalities. Numerical simulations are presented showing the enhanced performance of the proposed design compared to existing gradient tracking algorithms

Exploring The Potential of Probabilistic Shaping Technique in Quantum Key Distribution Systems

We investigated the role of probabilistic shaping in the optimization of the secure key rate of a continuous variable quantum key distribution system with discrete modulation in both homodyne and heterodyne scheme

Assessing a binary quantum channel exploiting a silicon photomultiplier based hybrid receiver

In quantum communication protocols, the use of photon-number-resolving detectors could open new perspectives by broadening the way to encode and decode information and merging the properties of discrete and continuous variables. In this work, we consider a quantum channel exploiting a silicon-photomultiplier-based receiver and evaluate its performance for quantum communication protocols under three possible configurations, defined by different post- processing of the detection outcomes. We investigate two scenarios: information transmission over the channel, quantified by the mutual information, and continuous-variable quantum key distribution, quantified by the key generation rate. The preliminary results encourage further use of this detection scheme in extended networks

Probabilistic Amplitude Shaping for Continuous-Variable Quantum Key Distribution with Discrete Modulation over a Wiretap Channel

To achieve the maximum information transfer and face a possible eavesdropper, the samples transmitted in continuous-variable quantum key distribution (CV-QKD) protocols are to be drawn from a continuous Gaussian distribution. As a matter of fact, in practical implementations the transmitter has a finite (power) dynamics and the Gaussian sampling can be only approximated. This requires the quantum protocols to operate at small powers. In this paper, we show that a suitable probabilistic amplitude shaping of a finite set of symbols allows to approximate at will the optimal channel capacity also for increasing average powers. We investigate the feasibility of this approach in the framework of CV-QKD, propose a protocol employing discrete quadrature amplitude modulation assisted with probabilistic amplitude shaping, and we perform the key generation rate analysis assuming a wiretap channel and lossless homodyne detection