Tapping wave energy through Longuet-Higgins microseism effect

International audienceIt is well-known, since the works of Miche (1944) and Longuet-Higgins (1950), that, under a standing wave system, second-order pressures at twice the wave frequency penetrate the water column down to the sea-°oor, whatever the waterdepth. Recently Gu¶evel proposed that energy could be extracted from the waves with a heaving horizontal plate at the sea bottom, located next to a re°ective cli® or sea-wall, and tuned to oscillate at twice the wave frequency. Encouraging preliminary experiments were conducted in ACRI's wavetank (Lajoie et al. 2007). In this paper we address the theoretical modeling of wave energy extraction with such a device, in the asymptotic case when the waterdepth is very large compared to the wavelength. In section I we assume that the ¯rst-order wave system is little modi¯ed, i.e. the power taken from the waves is a small portion of the power carried by the incoming wave. In section II we relieve this assumption and we show that one hundred percent of the wave power can be extracted, notwithstanding how large the waterdepth

Connectivity effects in the segmental self- and cross-reorientation of unentangled polymer melts

The segmental (bond) rotational dynamics in a polymer melt of unentangled, linear bead-spring chains is studied by molecular dynamics simulations. To single out the connectivity effects, states with limited deviations from the Gaussian behavior of the linear displacement are considered. Both the self and the cross bond-bond correlations with rank ℓ=1,2 are studied in detail. For ℓ=1 the correlation functions are precisely described by expressions involving the correlation functions of the chain modes. Several approximations concerning both the self- and the cross-correlations with ℓ=1,2 are developed and assessed. It is found that the simplified description of the excluded volume static effects derived elsewhere [D. Molin et al., J. Phys.: Condens. Matter 18, 7543 (2006)] well accounts for the short time cross-correlations. It also allows a proper modification of the Rouse theory which provides quantitative account of the intermediate and the long time decay of the rotational correlations with ℓ=1

Obliterative Endoaneurysmorrhaphy with Stent Graft Preservation for Treatment of Type II Progressive Endoleak

Objective/BackgroundPersistent type II endoleak (EL II) with sac enlargement after endovascular repair of abdominal aortic aneurysm requires treatment to prevent rupture. Embolization is not always effective. Conversion to open repair with stent graft (SG) explantation is a high risk option. The aim of this study was to evaluate the feasibility and immediate results of an alternative technique combining obliterative endoaneurysmorrhaphy (OEA) with SG preservation.MethodsThe open surgical technique combined sacotomy, ligation of all patent back-bleeding vessels and SG preservation. The aneurysmal shell was tightly closed over the SG to protect it from the intestines. An intra-aortic occlusion balloon was used when clamping was required.ResultsTwelve patients were treated with the OEA technique at Amiens University Hospital. All 12 procedures were successful. Four patients had previously undergone unsuccessful transarterial or translumbar embolization. Aortic clamping was performed in four cases. No SG migration or graft dislocation was observed. Follow up computed tomography scan at a median of 12 months showed shrinkage of the aneurysm sac with stable diameters and no recurrence of EL II in all cases.ConclusionThe OEA technique is an alternative option for the treatment of progressive EL II, which can be particularly useful after failure of embolization

TERREMOTI NELL’OMBRA: UN EVENTO CALABRESE NASCOSTO DAL GRANDE TERREMOTO DEL 1915

L’occorrenza di un terremoto distruttivo ha numerose implicazioni, sia di tipo fisico (modifica del campo di stress tettonico) che di tipo storico culturale. Nella storia sismica italiana l’occorrenza di forti terremoti ha generato spesso un aumento dell’attenzione verso questo fenomeno, ed è direttamente correlabile con alcune iniziative che hanno costituito la stessa tradizione storico-sismologica italiana, quali - ad esempio - la redazioni di importanti compilazioni sismologiche, (Giannozzo Manetti e Marcello Bonito, rispettivamente dopo i terremoti del 1456 e del 1688), o la nascita del servizio geodinamico italiano (all’indomani del terremoto ligure del 1887). Tuttavia i terremoti distruttivi hanno anche un effetto di ‘oscuramento’ nella tradizione storica di eventi meno forti, prossimi nello spazio (ma non necessariamente) e soprattutto nel tempo. Diversi casi storici sono stati segnalati da lavori recenti (Camassi e Castelli, 2005), e molti altri sono probabilmente ancora da ‘scoprire’. Nel presente lavoro si illustra un caso di questo genere, che ha la particolarità di verificarsi in tempi molto recenti, immediatamente a ridosso del grande terremoto della Marsica del 1915. Il terremoto colpisce la Calabria Settentrionale, a nord-ovest di Cosenza, e pur non modificando in modo significativo il quadro di conoscenze sulla sismicità dell’area, relativamente ‘ricco’, rappresenta comunque un caso significativo e uno spunto di riflessione importante sul tema della completezza storica delle informazioni sismologiche

Parentes silvestres da batata: áreas prioritárias para coleta no Brasil e variabilidade do germoplasma.

Dissertação (Mestrado) - Programa de Pós-Graduação em Agronomia, Faculdade de Agronomia Eliseu Maciel, Universidade Federal de Pelotas, 2017. Orientador: Gustavo Heiden; Coorientadora: Caroline Marques Castro

Isolation and characterisation of the first microsatellite markers for \u3ci\u3eCyperus rotundus\u3c/i\u3e

This is the first report of microsatellite markers for Cyperus rotundus. A total of 191 sequence-specific microsatellite markers were isolated and used to screen12 accessions of C. rotundus and one accession of Cyperus esculentus collected from 10 different countries. Polymorphisms were observed in 49% of the markers tested, 22% of the markers were monomorphic and 29% had weak or no amplification. The best 57 markers are reported, and cluster analysis was used to analyse their resolving power. BLASTx screening of the contig sequences was also performed. Multiallelic loci over all samples ranged from 24% to 60%. The maximum number of alleles detected by the markers suggests a polyploidy nature of all C. rotundus accessions tested, except for the sample N25-Brazil. Chromosome number was determined for N12-Taiwan and used as an internal flow cytometry standard to estimate the amount of DNA within haploid nuclei of the remaining material. Chromosome numbers estimated for C. rotundus were 16 and 24. The markers identified in this study can be used for the identification of biotypes and detection of potential crosses of C. rotundus, to implement management practices for the effective control of this weed

Evolution and adaptation in pseudomonas aeruginosa biofilms driven by mismatch repair system-deficient mutators

Pseudomonas aeruginosa is an important opportunistic pathogen causing chronic airway infections, especially in cystic fibrosis (CF) patients. The majority of the CF patients acquire P. aeruginosa during early childhood, and most of them develop chronic infections resulting in severe lung disease, which are rarely eradicated despite intensive antibiotic therapy. Current knowledge indicates that three major adaptive strategies, biofilm development, phenotypic diversification, and mutator phenotypes [driven by a defective mismatch repair system (MRS)], play important roles in P. aeruginosa chronic infections, but the relationship between these strategies is still poorly understood. We have used the flow-cell biofilm model system to investigate the impact of the mutS associated mutator phenotype on development, dynamics, diversification and adaptation of P. aeruginosa biofilms. Through competition experiments we demonstrate for the first time that P. aeruginosa MRS-deficient mutators had enhanced adaptability over wild-type strains when grown in structured biofilms but not as planktonic cells. This advantage was associated with enhanced micro-colony development and increased rates of phenotypic diversification, evidenced by biofilm architecture features and by a wider range and proportion of morphotypic colony variants, respectively. Additionally, morphotypic variants generated in mutator biofilms showed increased competitiveness, providing further evidence for mutator-driven adaptive evolution in the biofilm mode of growth. This work helps to understand the basis for the specific high proportion and role of mutators in chronic infections, where P. aeruginosa develops in biofilm communities.Fil: Lujan, Adela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Química Biológica de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Centro de Investigaciones en Química Biológica de Córdoba; Argentina. Universidad Católica de Córdoba. Instituto de Investigaciones en Recursos Naturales y Sustentabilidad José Sanchez Labrador S. J. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Recursos Naturales y Sustentabilidad José Sanchez Labrador S. J.; ArgentinaFil: Maciá, María D.. Instituto de Investigación Sanitaria Illes Balears; EspañaFil: Yang, Liang. Technical University of Denmark; DinamarcaFil: Molin, Søren. Technical University of Denmark; DinamarcaFil: Oliver, Antonio. Instituto de Investigación Sanitaria Illes Balears; EspañaFil: Smania, Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Química Biológica de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Centro de Investigaciones en Química Biológica de Córdoba; Argentin

Proteins to Order Use of Synthetic DNA to Generate Site-Specific Mutations

The ability to cause specific changes in the amino acid sequences of proteins would greatly advance studies on the influence of protein structure on biochemical function. If the desired changes can once be made in the nucleic acid which encodes the protein, one can use cloning in an appropriate microorganism to produce essentially limitless quantities of the mutant protein. We describe here the application of oligonucleotide-directed site-specific mutagenesis to accomplish this objective for the enzyme B-lactamase, the gene for which is contained in the plasmid pBR322. The method uses a procedure to screen for mutant clones which depends on the DNA in the various colonies and not on the properties of the mutant protein; the method can, therefore, be widely applied and does not require, in each separate case, the development of a screening procedure which depends on some phenotypic difference between mutant and wild-type protein