Polarization Impact in TanDEM-X Data Over Vertical-Oriented Vegetation: The Paddy-Rice Case Study

It has been recently shown that the TanDEM-X mission is capable of tracking the plant growth of rice paddies. The precision of the elevation measure depends on the physical interaction between the synthetic aperture radar (SAR) signal and the canopy. In this letter, this interaction is studied by considering the signal polarization. In particular, the vertical and horizontal wave polarizations are compared, and their performance in the temporal mapping of the crop height is analyzed. The temporal elevation difference analysis shows a monotonically increasing trend within the reproductive stage of the canopy, with maximum height discrepancies between polarizations of about 9 cm. From an operational point of view of InSAR-based vegetation height measurements, this letter demonstrates that the oriented structure of the canopy shall be considered not only in polarimetric InSAR studies but also in the interpretation of bistatic spaceborne interferometric elevation models

Detecting Building Layovers in a SAR Interferometric Processor Without External References

A novel technique for the derivation of building layovers is presented. It makes use of the behaviour of the geocoding processing stage embedded in an interferometric SAR processor for this particular case. It is shown how layover pixels create a regular pattern in the range mapping matrices, with a multiple mapping of a single SAR pixel for different DEM cells. The exploitation of these patterns yields a generation of a layover map without the use of external supports. The integration in an interferometric processor with a limited additional computational load and the capability to isolate building signatures are additional benefits. The algorithm is tested on a TanDEM-X spotlight acquisition over Berlin (Germany)

In vivo functional and molecular characterization of the Penicillin-Binding Protein 4 (DacB) of Pseudomonas aeruginosa

Background: Community and nosocomial infections by Pseudomonas aeruginosa still create a major therapeutic challenge. The resistance of this opportunist pathogen to β-lactam antibiotics is determined mainly by production of the inactivating enzyme AmpC, a class C cephalosporinase with a regulation system more complex than those found in members of the Enterobacteriaceae family. This regulatory system also participates directly in peptidoglycan turnover and recycling. One of the regulatory mechanisms for AmpC expression, recently identified in clinical isolates, is the inactivation of LMM-PBP4 (Low-Molecular-Mass Penicillin-Binding Protein 4), a protein whose catalytic activity on natural substrates has remained uncharacterized until now. Results: We carried out in vivo activity trials for LMM-PBP4 of Pseudomonas aeruginosa on macromolecular peptidoglycan of Escherichia coli and Pseudomonas aeruginosa. The results showed a decrease in the relative quantity of dimeric, trimeric and anhydrous units, and a smaller reduction in monomer disaccharide pentapeptide (M5) levels, validating the occurrence of D,D-carboxypeptidase and D,D-endopeptidase activities. Under conditions of induction for this protein and cefoxitin treatment, the reduction in M5 is not fully efficient, implying that LMM-PBP4 of Pseudomonas aeruginosa presents better behaviour as a D,D-endopeptidase. Kinetic evaluation of the direct D,D-peptidase activity of this protein on natural muropeptides M5 and D45 confirmed this bifunctionality and the greater affinity of LMM-PBP4 for its dimeric substrate. A three-dimensional model for the monomeric unit of LMM-PBP4 provided structural information which supports its catalytic performance. Conclusions: LMM-PBP4 of Pseudomonas aeruginosa is a bifunctional enzyme presenting both D,D-carboxypeptidase and D,D-endopeptidase activities; the D,D-endopeptidase function is predominant. Our study provides unprecedented functional and structural information which supports the proposal of this protein as a potential hydrolase-autolysin associated with peptidoglycan maturation and recycling. The fact that mutant PBP4 induces AmpC, may indicate that a putative muropeptide-subunit product of the DD-EPase activity of PBP4 could be a negative regulator of the pathway. This data contributes to understanding of the regulatory aspects of resistance to β-lactam antibiotics in this bacterial model.Spanish Ministerio de Ciencia e Innovación, DIVINOCELL FP7 HEALTH-F3-2009-223431 from the European Commission and DIUFRO08-0060 from the Dirección de Investigación of the Universidad de La Frontera of ChilePeer Reviewe

Rice Plant Height Monitoring from Space with Bistatic Interferometry

This chapter provides an overview of the possibility to derive paddy rice plant heights with spaceborne bistatic SAR interferometry (InSAR). By using the only available interferometer in space, TanDEM-X, an investigation of rice crops located in Turkey is performed. Before analyzing the main outcomes, an introduction to the generation of elevation models with InSAR is provided, with a special focus on the agricultural land cover. The processing chain and the modifications foreseen to properly produce plant elevations and a roadmap for the quality assessment are described. The results obtained, with a very high interferometric coherence supporting an accurate estimation due to a limited electromagnetic wave penetration into the canopy, support a temporal change analysis on a field-by-field basis. For the purpose, an automatic approach to segment the fields without external auxiliary data is also provided. The study is concluded with an analysis of the impact of the wave polarization in the results

Nonnegative solutions to an elliptic problem with nonlinear absorption and a nonlinear incoming flux on the boundary

In this paper we perform an extensive study of the existence, uniqueness (or multiplicity) and stability of nonnegative solutions to the semilinear elliptic equation −∆u = λu − u p in Ω, with the nonlinear boundary condition ∂u/∂ν = u r on ∂Ω. Here Ω is a smooth bounded domain of IRd with outward unit normal ν, λ is a real parameter and p, r > 0. We also give the precise behavior of solutions for large |λ| in the cases where they exist. The proofs are mainly based on bifurcation techniques, sub-supersolutions and variational methods.Ministerio de Ciencia y TecnologíaFondo Europeo de Desarrollo Regiona

The worsening impacts of land reclamation assessed with Sentinel-1: The Rize (Turkey) test case

Massive amounts of land are being reclaimed to build airports, new cities, ports, and highways. Hundreds of kilometers are added each year, as coastlines are extended further out to the sea. In this paper, this urbanization approach is monitored by Persistent Scatterer Interferometry (PSI) technique with Sentinel-1 SAR data. The study aims to explore this technology in order to support local authorities to detect and evaluate subtle terrain displacements. For this purpose, a large 3-years Sentinel-1 stack composed by 92 images acquired between 07/01/2015 to 27/01/2018 is employed and stacking techniques are chosen to assess ground motion. The test site of this study, Rize, Turkey, has been declared at high risk of collapse and radical solutions such as the relocation of the entire city in another area are been taken into consideration. A media fact-checking approach, i.e. evaluating national and international press releases on the test site, is considered for the paper and this work presents many findings in different areas of the city. For instance, alerts are confirmed by inspecting several buildings reported by the press. Critical infrastructures are monitored as well. Portions of the harbor show high displacement rates, up to 1 cm/year, proving reported warnings. Rural villages belonging to the same municipality are also investigated and a mountainous village affected by landslide is considered in the study. Sentinel-1 is demonstrated to be a suitable system to detect and monitor small changes or buildings and infrastructures for these scenarios. These changes may be highly indicative of imminent damage which can lead to the loss of the structural integrity and subsequent failure of the structure in the long-term. In Rize, only a few known motion-critical structures are monitored daily with in-situ technologies. SAR interferometry can assist to save expensive inspection and monitoring services, especially in highly critical cases such as the one studied in this paper

Phase control of a longitudinal momentum entangled photon state by a deformable membrane mirror

We propose a paradigmatic demonstration of the potentialities of a deformable mirror for closed-loop control of a two-photon momentum-entangled state, subject to phase fluctuations. A custom-made membrane mirror is used to set a relative phase shift between the arms of an interferometric apparatus. The control algorithm estimates the phase of the quantum state, by measurements of the coincidence events at the output ports of the interferometer, and uses the measurements results to provide a feedback signal to the deformable mirror. Stabilization of the coincidence rate to within 1.5 standard deviation of the Poissonian noise is demonstrated over 2000 seconds.Comment: RevTex, 6 page

Toward Waveform Nonlinear Optics Using Multimillijoule Sub-Cycle Waveform Synthesizers

Waveform nonlinear optics aims to study and control the nonlinear interactions of matter with extremely short optical waveforms custom-tailored within a single cycle of light. Different technological routes to generate such multimillijoule sub-optical-cycle waveforms are currently pursued, opening up unprecedented opportunities in attoscience and strong-field physics. Here, we discuss the experimental schemes, introduce the technological challenges, and present our experimental results on high-energy sub-cycle optical waveform synthesis based on (1) parametric amplification and (2) induced-phase modulation in a two-color-driven gas-filled hollow-core fiber compressor. More specifically, for (1), we demonstrate a carrier-envelope-phase (CEP)-stable, multimillijoule three-channel parametric waveform synthesizer generating a >2-octave-wide spectrum (0.52-2.4 μm). After two amplification stages, the combined 125-μJ output supports 1.9-fs FWHM waveforms; energy scaling to >2 mJ is achieved after three amplification stages. FROG pulse characterization of all three second-stage outputs demonstrates the feasibility to recompress all three channels simultaneously close to the Fourier limit and shows the flexibility of our intricate dispersion management scheme for different experimental situations. For (2), we generate CEP-stable 1.7-mJ waveforms covering 365-930 nm (measured at 1% of the peak intensity) obtained from induced-phase modulation in a two-color-driven gas-filled hollow-core fiber. Using custom-designed double-chirped mirrors and a UV spatial light modulator will permit compression close to the 0.9-fs FWHM transform limit. These novel sources will become versatile tools for controlling strong-field interactions in matter and for attosecond pump-probe spectroscopy using VIS/IR and XUV/soft-X-ray pulses

NEW THERAPEUTIC PERSPECTIVES IN IRRITABLE BOWEL SYNDROME: TARGETING LOW-GRADE INFLAMMATION, IMMUNO-NEUROENDOCRINE AXIS, MOTILITY, SDECRETION AND BEYOND

Irritable bowel syndrome (IBS) is a chronic, recurring, and remitting functional disorder of the gastrointestinal tract characterized by abdominal pain, distention, and changes in bowel habits. Although there are several drugs for IBS, effective and approved treatments for one or more of the symptoms for various IBS subtypes are needed. Improved understanding of pathophysiological mechanisms such as the role of impaired bile acid metabolism, neurohormonal regulation, immune, dysfunction, the epithelial barrier and the secretory properties of the gut has led to advancements in the treatment of IBS. With regards to therapies for restoring intestinal permeability, multiple studies with prebiotics and probiotics are ongoing, even if to date their efficacy has been limited. In parallel, much progress has been made in targeting low-grade inflammation, especially through the introduction of drugs such as mesalazine and rifaximin, even if a better knowledge of the mechanisms underlying the low-grade inflammation in IBS may allow the design of clinical trials that test the efficacy and safety of such drugs. This literature review aims to summarize the findings related to new and investigational therapeutic agents for IBS, most recently developed in preclinical as well as Phase 1 and Phase 2 clinical studies