Integrated scheme of rapid environmental assessment for shallow water acoustics

Predicting sound propagation in shallow or very shallow water environments requires that the frequency-dependent acoustic properties be assessed for all components of the waveguide, i.e., the water column, sea bottom and sea surface interface. During the Maritime Rapid Environmental Assessment MREA?BP'07 sea trial in April-May 2007, south of Elba Island in the Mediterranean Sea, an integrated MREA scheme has been implemented to provide a full 4D (3D+T) environmental picture that is directly exploitable by acoustic propagation models. Based on a joint multi-disciplinary effort, several standard and advanced techniques of environmental characterization covering the fields of underwater acoustics, physical oceanography and geophysics have been combined within a coherent scheme of data acquisition, processing and assimilation. The paper presents the whole architecture of the implemented scheme. Based on a preliminary analysis of MREA?BP'07 data, advantages and drawbacks of the approach will be discussed. Ways ahead for further improvement and perspectives are finally drawn

Geoacoustic inversion in the frequency range 0.8-1.6 kHz with drifting sparse arrays during MREA/BP'07 experiment

In order to evaluate properly the acoustic propagation characteristics in shallow water environments, it is well established that appropriate knowledge of the acoustic properties of the seabottom is required. In the last decade, full-field geoacoustic inversion techniques have been demonstrated to provide adequate methodologies to assess those properties. However, several of the developed techniques may suffer a lack of adequacy to the design of low-frequency active sonar systems (LFAS) for which the assessment of seabottom characteristics are drawn. For instance most matched-field inversion techniques demonstrated so far use acoustical signals at much lower frequencies than those of the sonar. Furthermore, some of the techniques may be difficult to be handled in an "operationally relevant context" since they are based on relatively complex designed systems such as highly instrumented vertical line arrays spanning the whole water column. In this paper, we investigate the potential of medium-frequency acoustical signals (0.8-1.6 kHz) received at several ranges on a field of drifting sparse arrays, eventually reduced to a couple of hydrophones, for spatially-coherent geoacoustic inversion purposes. The experimental datasets of the Maritime Rapid Environmental Assessment MREA/BP'07 sea trial south of Elba Island in the Mediterranean Sea are used to support this study

Integrated microfluidic biosensing platform for simultaneous confocal microscopy and electrophysiological measurements on bilayer lipid membranes and ion channels

Combining high-resolution imaging and electrophysiological recordings is key for various types of experimentation on lipid bilayers and ion channels. Here, we propose an integrated biosensing platform consisting of a microfluidic cartridge and a dedicated chip-holder to conduct such dual measurements on suspended lipid bilayers, in a user-friendly manner. To illustrate the potential of the integrated platform, we characterize lipid bilayers in terms of thickness and fluidity while simultaneously monitoring single ion channel currents. For that purpose, POPC lipid bilayers are supplemented with a fluorescently-tagged phospholipid (NBD-PE, 1% mol) for Fluorescence Recovery After Photobleaching (FRAP) measurements and a model ion channel (gramicidin, 1 nM). These combined measurements reveal that NBD-PE has no effect on the lipid bilayer thickness while gramicidin induces thinning of the membrane. Furthermore, the presence of gramicidin does not alter the lipid bilayer fluidity. Surprisingly, in lipid bilayers supplemented with both probes, a reduction in gramicidin open probability and lifetime is observed compared to lipid bilayers with gramicidin only, suggesting an influence of NBD-PE on the gramicidin ion function. Altogether, our proposed microfluidic biosensing platform in combination with the herein presented multi-parametric measurement scheme paves the way to explore the interdependent relationship between lipid bilayer properties and ion channel function

Predictive ageing of elastomers: Oxidation driven modulus changes for polychloroprene

The oxidative ageing in the range of 60 °C–140 °C of sulfur vulcanized polychloroprene has been studied by FTIR spectroscopy (double bond consumption), modulus changes and oxygen absorption measurements. Experiments were carried out on thin films and thick samples to investigate both homogeneous and inhomogeneous (diffusion controlled) oxidation with the goal of establishing the underlying correlation between oxidative degradation chemistry and mechanical property changes. A correlation between oxidatively driven degradation chemistry and modulus is possible using the established approaches of rubber elasticity where an effective crosslinking yield due to double bond reactions is of the order of 30% for this material (i.e. the loss of 3 double bonds results in one effective crosslink associated with material hardening). It is then possible to predict modulus changes induced by oxidation for vulcanized and unstabilized polychloroprene rubber. A kinetic model is introduced with two propagation reactions (hydrogen abstraction and radical addition to double bonds) and two stabilization processes involving sulfur containing moieties from the vulcanization process. The kinetic scheme was solved and the relevant rate constants determined. This model can adequately predict modulus changes in films and thick samples as a function of time and spatially resolved

Test of CPT Symmetry and Quantum Mechanics with Experimental data from CPLEAR

We use fits to recent published CPLEAR data on neutral kaon decays to $\pi^+\pi^-$ and $\pi e\nu$ to constrain the CPT--violation parameters appearing in a formulation of the neutral kaon system as an open quantum-mechanical system. The obtained upper limits of the CPT--violation parameters are approaching the range suggested by certain ideas concerning quantum gravity.Comment: 9 pages of uuencoded postscript (includes 3 figures

Tests of the Equivalence Principle with Neutral Kaons

We test the Principle of Equivalence for particles and antiparticles, using CPLEAR data on tagged K0 and K0bar decays into pi^+ pi^-. For the first time, we search for possible annual, monthly and diurnal modulations of the observables |eta_{+-}| and phi_{+-}, that could be correlated with variations in astrophysical potentials. Within the accuracy of CPLEAR, the measured values of |eta_{+-}| and phi_{+-} are found not to be correlated with changes of the gravitational potential. We analyze data assuming effective scalar, vector and tensor interactions, and we conclude that the Principle of Equivalence between particles and antiparticles holds to a level of 6.5, 4.3 and 1.8 x 10^{-9}, respectively, for scalar, vector and tensor potentials originating from the Sun with a range much greater than the distance Earth-Sun. We also study energy-dependent effects that might arise from vector or tensor interactions. Finally, we compile upper limits on the gravitational coupling difference between K0 and K0bar as a function of the scalar, vector and tensor interaction range.Comment: 15 pages latex 2e, five figures, one style file (cernart.csl) incorporate

Allele frequencies of hemojuvelin gene (HJV) I222N and G320V missense mutations in white and African American subjects from the general Alabama population

BACKGROUND: Homozygosity or compound heterozygosity for coding region mutations of the hemojuvelin gene (HJV) in whites is a cause of early age-of-onset iron overload (juvenile hemochromatosis), and of hemochromatosis phenotypes in some young or middle-aged adults. HJV coding region mutations have also been identified recently in African American primary iron overload and control subjects. Primary iron overload unexplained by typical hemochromatosis-associated HFE genotypes is common in white and black adults in Alabama, and HJV I222N and G320V were detected in a white Alabama juvenile hemochromatosis index patient. Thus, we estimated the frequency of the HJV missense mutations I222N and G320V in adult whites and African Americans from Alabama general population convenience samples. METHODS: We evaluated the genomic DNA of 241 Alabama white and 124 African American adults who reported no history of hemochromatosis or iron overload to detect HJV missense mutations I222N and G320V using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Analysis for HJV I222N was performed in 240 whites and 124 African Americans. Analysis for HJV G320V was performed in 241 whites and 118 African Americans. RESULTS: One of 240 white control subjects was heterozygous for HJV I222N; she was also heterozygous for HFE C282Y, but had normal serum iron measures and bone marrow iron stores. HJV I222N was not detected in 124 African American subjects. HJV G320V was not detected in 241 white or 118 African American subjects. CONCLUSIONS: HJV I222N and G320V are probably uncommon causes or modifiers of primary iron overload in adult whites and African Americans in Alabama. Double heterozygosity for HJV I222N and HFE C282Y may not promote increased iron absorption

Cancer-ID:Toward Identification of Cancer by Tumor-Derived Extracellular Vesicles in Blood

Extracellular vesicles (EVs) have great potential as biomarkers since their composition and concentration in biofluids are disease state dependent and their cargo can contain disease-related information. Large tumor-derived EVs (tdEVs, >1μm) in blood from cancer patients are associated with poor outcome, and changes in their number can be used to monitor therapy effectiveness. Whereas, small tumor-derived EVs (<1μm) are likely to outnumber their larger counterparts, thereby offering better statistical significance, identification and quantification of small tdEVs are more challenging. In the blood of cancer patients, a subpopulation of EVs originate from tumor cells, but these EVs are outnumbered by non-EV particles and EVs from other origin. In the Dutch NWO Perspectief Cancer-ID program, we developed and evaluated detection and characterization techniques to distinguish EVs from non-EV particles and other EVs. Despite low signal amplitudes, we identified characteristics of these small tdEVs that may enable the enumeration of small tdEVs and extract relevant information. The insights obtained from Cancer-ID can help to explore the full potential of tdEVs in the clinic