Seismic Signatures of Fractured Porous Rocks: The Partially Saturated Case

Seismic attenuation and phase velocity dispersion due to mesoscopic fluid pressure diffusion (FPD) have received increasing attention due to their inherent sensitivity to the hydromechanical properties of monosaturated fractured porous media. While FPD processes are directly affected by key macroscopic properties of fractured rocks, such as fracture density and fracture connectivity, there is, as of yet, a lack of comprehension of the associated characteristics when multiple immiscible phases saturate the probed fractured medium. In this work, we analyze the variations experienced by P and S wave attenuation and phase velocity dispersion when CO2 percolates into an initially brine-saturated fractured porous rock. We study such variations considering a simple model of a porous rock containing intersecting orthogonal fractures as well as a more complex model comprising a fracture network. In the latter, we simulate the flow of a CO2 plume into the medium using an invasion percolation procedure. Representative samples are subjected to numerical upscaling experiments, consisting of compression and shear tests, prior to and after the CO2 invasion process. Results show that fracture-to-background FPD is only sensitive to the presence of CO2, which decreases its effects. However, fracture-to-fracture FPD depends on both the overall CO2 saturation and the fluid distribution within the fracture network. While the former modulates the magnitude of the dissipation, the latter can give rise to a novel FPD process occurring between CO2-saturated and brine-saturated regions of the fracture network.Fil: Solazzi, Santiago Gabriel. Universite de Lausanne; Suiza. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hunziker, Jürg. Universite de Lausanne; SuizaFil: Caspari, Eva. Universite de Lausanne; Suiza. Montanuniversität Leoben; AustriaFil: Rubino, Jorge German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Favino, Marco. Universite de Lausanne; SuizaFil: Holliger, Klaus. Universite de Lausanne; Suiza. Zhejiang University; República de Chin

Representative elementary volumes for evaluating effective seismic properties of heterogeneous poroelastic media

Understanding and quantifying seismic energy dissipation in fluid-saturated porous rocks is of considerable interest because it offers the perspective of extracting information with regard to the elastic and hydraulic rock properties. An important, if not dominant, attenuation mechanism prevailing in the seismic frequency band is wave-induced fluid pressure diffusion in response to the contrasts in elastic stiffness in the mesoscopic-scale range. An effective way to estimate seismic velocity dispersion and attenuation related to this phenomenon is through the application of numerical upscaling procedures to synthetic rock samples of interest. However, the estimated seismic properties are meaningful only if the underlying sample volume is at least of the size of a representative elementary volume (REV). In the given context, the definition of an REV and the corresponding implications for the estimation of the effective seismic properties remain largely unexplored. To alleviate this problem, we have studied the characteristics of REVs for a set of idealized rock samples sharing high levels of velocity dispersion and attenuation. For periodically heterogeneous poroelastic media, the REV size was driven by boundary condition effects. Our results determined that boundary condition effects were absent for layered media and negligible in the presence of patchy saturation. Conversely, strong boundary condition effects arose in the presence of a periodic distribution of finite-length fractures, thus leading to large REV sizes. The results thus point to the importance of carefully determining the REV sizes of heterogeneous porous rocks for computing effective seismic properties, especially in the presence of strong dry frame stiffness contrasts. </jats:p

Structural Diversity in Early-Stage Biofilm Formation on Microplastics Depends on Environmental Medium and Polymer Properties

Plastics entering the environment can not only undergo physical degradation and fragmentation processes, but they also tend to be colonized by microorganisms. Microbial colonization and the subsequent biofilm formation on plastics can alter their palatability to organisms and result in a higher ingestion as compared to pristine plastics. To date, the early stage of biofilm formation on plastic materials has not been investigated in context of the environmental medium and polymer properties. We explored the early-stage biofilm formation on polyamide (PA), polyethylene terephthalate (PET), and polyvinyl chloride (PVC) after incubation in freshwater and artificial seawater and categorized the structural diversity on images obtained via scanning electron microscopy. Furthermore, by the measurement of the initial &zeta;-potential of the plastic materials, we found that PA with the highest negative &zeta;-potential tended to have the highest structural diversity, followed by PET and PVC after incubation in freshwater. However, PVC with the lowest negative &zeta;-potential showed the highest structural diversity after incubation in seawater, indicating that the structural diversity is additionally dependent on the incubation medium. Our results give insights into how the incubation medium and polymer properties can influence the early-stage biofilm formation of just recently environmentally exposed microplastics. These differences are responsible for whether organisms may ingest microplastic particles with their food or not

Behavior and Impact of Zirconium in the Soil–Plant System: Plant Uptake and Phytotoxicity

Because of the large number of sites they pollute, toxic metals that contaminate terrestrial ecosystems are increasingly of environmental and sanitary concern (Uzu et al. 2010, 2011; Shahid et al. 2011a, b, 2012a). Among such metals is zirconium (Zr), which has the atomic number 40 and is a transition metal that resembles titanium in physical and chemical properties (Zaccone et al. 2008). Zr is widely used in many chemical industry processes and in nuclear reactors (Sandoval et al. 2011; Kamal et al. 2011), owing to its useful properties like hardness, corrosion-resistance and permeable to neutrons (Mushtaq 2012). Hence, the recent increased use of Zr by industry, and the occurrence of the Chernobyl and Fukashima catastrophe have enhanced environmental levels in soil and waters (Yirchenko and Agapkina 1993; Mosulishvili et al. 1994 ; Kruglov et al. 1996)

Die Europäisierung der öffentlichen Aufgaben

Die zunehmende Europäisierung der öffentlichen Aufgaben ist einer der wichtigsten Trends im Wandel der Staatstätigkeit in der Bundesrepublik Deutschland und in anderen Mitgliedstaaten der Europäischen Union. In diesem Essay werden die Stufen der Europäisierung der Staatstätigkeit nachgezeichnet, in Weiterführung von Lindberg/Scheingold (1970) und Schmitter (1996) quantifiziert und hinsichtlich ihrer Kosten und ihres Nutzen erörtert. Inhalt: Stufen der Europäisierung der öffentlichen Aufgaben Der Europäisierungsgrad der öffentlichen Aufgaben von 1950 bis zum Ende des 20. Jahrhunderts Vom Nutzen und von den Kosten der Europäisierung der öffentlichen Angelegenheiten Verzeichnis der zitierten Literatu

Contextual factors in shared decision making: a randomised controlled trial in women with a strong suspicion of breast cancer

Decision aids in North American breast cancer outpatients have been shown to assist with treatment decision making and reduce decisional conflict. To date, appropriate delivery formats to effectively increase patient participation in newly diagnosed breast cancer inpatients have not been investigated in the context of German health care provision. The impact of a decision aid intervention was studied in patients (n=111) with a strong suspicion of breast cancer in a randomised controlled trial. The primary outcome variable was decisional conflict. Participants were followed up 1 week post-intervention with a retention rate of 92%. Analyses revealed that the intervention group felt better informed (ηp2=0.06) but did not experience an overall reduction in decisional conflict as compared with the control group. The intervention had no effect on uptake rates of treatment options, length of consultation with the surgeon, time point of treatment decision making, perceived involvement in decision making, neither decision related nor general patient satisfaction. Patients who received the decision aid intervention experienced a small benefit with regards to how informed they felt about advantages and disadvantages of relevant treatment options. Results are discussed in terms of contextual factors and individual differences as moderators of treatment decision aid effectiveness

Sixty Years of Modern Human Origins in the American Anthropological Association

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65197/1/aa.2003.105.1.89.pd

Surveillance of FAP: a prospective blinded comparison of capsule endoscopy and other GI imaging to detect small bowel polyps

Background: Familial adenomatous polyposis (FAP) is a hereditary disorder characterized by polyposis along the gastrointestinal tract. Information on adenoma status below the duodenum has previously been restricted due to its inaccessibility in vivo. Ca

An annotated checklist of bryophytes of Europe, Macaronesia and Cyprus

Introduction. Following on from work on the European bryophyte Red List, the taxonomically and nomenclaturally updated spreadsheets used for that project have been expanded into a new checklist for the bryophytes of Europe. Methods. A steering group of ten European bryologists was convened, and over the course of a year, the spreadsheets were compared with previous European checklists, and all changes noted. Recent literature was searched extensively. A taxonomic system was agreed, and the advice and expertise of many European bryologists sought. Key results. A new European checklist of bryophytes, comprising hornworts, liverworts and mosses, is presented. Fifteen new combinations are proposed. Conclusions. This checklist provides a snapshot of the current European bryophyte flora in 2019. It will already be out-of-date on publication, and further research, particularly molecular work, can be expected to result in many more changes over the next few years.Peer reviewe