Engineered bidirectional communication mediates a consensus in a microbial biofilm consortium

Microbial consortia form when multiple species colocalize and communally generate a function that none is capable of alone. Consortia abound in nature, and their cooperative metabolic activities influence everything from biodiversity in the global food chain to human weight gain. Here, we present an engineered consortium in which the microbial members communicate with each other and exhibit a “consensus” gene expression response. Two colocalized populations of Escherichia coli converse bidirectionally by exchanging acyl-homoserine lactone signals. The consortium generates the gene-expression response if and only if both populations are present at sufficient cell densities. Because neither population can respond without the other's signal, this consensus function can be considered a logical AND gate in which the inputs are cell populations. The microbial consensus consortium operates in diverse growth modes, including in a biofilm, where it sustains its response for several days

Acoustic and mechanical properties of Nankai accretionary prism core samples

International audienceWe studied undeformed sediment and accreted strata recently recovered by Ocean Drilling Program/Integrated Ocean Drilling Program (ODP/IODP) drilling in Nankai Trough convergent margin to unravel the changes in physical properties from initial deposition to incipient deformation. We have derived acoustic (Vp) and mechanical (uniaxial poroelastic compliance, compaction amplitude) properties of samples from various drill sites along the Muroto (ODP 1173) and Kii transects (IODP C0001, C0002, C0006, and C0007) from isotropic loading tests where confining and pore pressure were independently applied. We quantified the dependence of Vp on both effective (Peff) and confining (Pc) pressure, which can be used to correct atmospheric pressure measurements of Vp. Experimental Vp obtained on core samples extrapolated to in situ conditions are slightly higher than logging-derived velocities, which can be attributed either to velocity dispersion or to the effect of large-scale faults and weak zones on waves with longer wavelength. In the high-porosity (30%-60%) tested sediments, velocities are controlled at first order by porosity and not by lithology, which is in agreement with our static measurements of drained framework incompressibility, much smaller than fluid incompressibility. Rather than framework incompressibility, shear modulus is probably the second-order control on Vp, accounting for most of the difference between actual Vp and the prediction by Wood's (1941) suspension model. We also quantified the mechanical state of Nankai samples in terms of anisotropy, diagenesis, and consolidation. Both acoustic and mechanical parameters reveal similar values in vertical and horizontal directions, attesting to the very low anisotropy of the tested material. When considering the porous samples of the Upper Shikoku Basin sediments (Site 1173) as examples of diagenetically cemented material, several mechanical and acoustic attributes appeared as reliable experimental indicators of the presence of intergrain cementation. We also detected incipient cementation in samples from IODP Site C0001 (accretionary prism unit). In terms of consolidation, we distinguished two classes of material response (shallow, deformable samples and deep, hardly deformable ones) based on the amount of compaction upon application of a Peff large with respect to the inferred in situ value, with a transition that might be related to a critical porosity

Structure and tectonic evolution of the Anatolian plateau in eastern Turkey

This paper was published by the Geological Society of America (GSA). Copyright 2006, GSA. See also: http://granite.geosociety.org/bookstore/default.asp?oID=0&catID=9&pID=SPE409; http://atlas.geo.cornell.edu/turkey/publications/Barazangi-et-al_2006.htmThe Cenozoic geology and the present lithospheric and upper mantle structure of the Anatolian plateau in eastern Turkey and nearby regions are the result of the final collision and suturing of the continental Arabian plate to the Turkish terranes (i.e., micro-continents). This process of collision and suturing was strongly influenced by three active structures in the region: the Caucasus mountains, the Aegean subduction zone, and the Dead Sea fault system. Understanding these three major tectonic elements are important for the development of a robust model for the formation of the Anatolian plateau. We show that the Anatolian plateau lithosphere in eastern Turkey has no lithospheric mantle, i.e., the crust floats on a partially molten asthenosphere. The average thickness of the crust in the region is approximately 45 km. The uppermost mantle beneath this crustal block strongly attenuates Sn waves and has one of the lowest Pn velocities on earth (about 7.6 km/s). The Anatolian plateau, with an average of 2 km elevation is dissected by numerous active, seismogenic faults (mostly strike-slip and some thrust type). Neogene and Quaternary volcanism with varying composition is widespread and covers more than half of the region. We argue that the northward subduction of the northern and the southern branches of the Neo-Tethyan oceanic lithosphere since the Mesozoic has resulted in the development of arc and back-arc volcanism (i.e., the Pontide and Bitlis systems) and the development of the eastern Anatolian accretionary complex that covers a large area of eastern Turkey. The northward subduction of the southern Neo-Tethys considerably thinned and weakened the overriding Eurasian plate above the descending oceanic lithosphere of the Arabian plate. The final suturing of the continental Arabian plate with the Turkish terranes in the Miocene and the continued convergence of Arabia relative to Eurasia has resulted in the shortening of the accretionary complex both in the forearc and the back-arc regions and the development of a broad zone with numerous strike-slip faults. The mobilization of the Caucasus is also partially a consequence of this convergence. The documented major episode of widespread volcanism at about 11 Ma is probably related to the breakoff of the shallowly descending oceanic segment of the Arabian lithosphere beneath eastern Turkey. The continued convergence of Arabia relative to Eurasia has resulted in the development of the North Anatolian fault (NAF) and subsequently the East Anatolian fault (EAF) in the Pliocene. At about this time, the northern segment of the Dead Sea fault (DSF) also developed in Lebanon and northwest Syria and joined the EAF to form the Anatolian - Arabian - African triple junction in the Maras region of southern Turkey. The development of these fault systems (i.e., NAF, EAF, and DSF) provided the mechanism for the tectonic escape of the Anatolian crustal block towards the Aegean arc system

Persistent elastic behavior above a megathrust rupture patch: Nias island, West Sumatra

We quantify fore-arc deformation using fossil reefs to test the assumption commonly made in seismic cycle models that anelastic deformation of the fore arc is negligible. Elevated coral microatolls, paleoreef flats, and chenier plains show that the Sumatran outer arc island of Nias has experienced a complex pattern of relatively slow long-term uplift and subsidence during the Holocene epoch. This same island rose up to 2.9 m during the Mw 8.7 Sunda megathrust rupture in 2005. The mismatch between the 2005 and Holocene uplift patterns, along with the overall low rates of Holocene deformation, reflects the dominance of elastic strain accumulation and release along this section of the Sunda outer arc high and the relatively subordinate role of upper plate deformation in accommodating long-term plate convergence. The fraction of 2005 uplift that will be retained permanently is generally <4% for sites that experienced more than 0.25 m of coseismic uplift. Average uplift rates since the mid-Holocene range from 1.5 to −0.2 mm/a and are highest on the eastern coast of Nias, where coseismic uplift was nearly zero in 2005. The pattern of long-term uplift and subsidence is consistent with slow deformation of Nias along closely spaced folds in the north and trenchward dipping back thrusts in the southeast. Low Holocene tectonic uplift rates provide for excellent geomorphic and stratigraphic preservation of the mid-Holocene relative sea level high, which was under way by ∼7.3 ka and persisted until ∼2 ka

Japan Sea, opening history and mechanism: A synthesis

Laurent Jolivet est Professeur à l'Université d'Orléans au 1er Septembre 2009International audienceThe respective tectonic effects of back arc spreading and continental collision in Asia are considered either as two independent processes or as closely interrelated. Extrusion tectonics assumes that the opening of the South China Sea and the left-lateral motion along the Red River fault are geometrically linked in a pull-apart manner. This model is not accepted by several workers because the structural link between the two processes is not clearly demonstrated. In the case of the Japan Sea, we can show without ambiguity that back arc opening was controlled by large intracontinental strike-slip faults which can be easily understood as effects of the India-Asia collision far from the indenter. The Japan Sea opened in the early Miocene in a broad pull-apart zone between two major dextral strike-slip shear zones. The first one extends from north Sakhalin to central Japan along 2000 km, it has accommodated about 400 km of finite displacement. Deformation along it varies from dextral transpression in the north to dextral transtension in the south. The second is between Korea and SW Japan and has accommodated a smaller displacement of about 200 km. The extensional domain in between lies in the back arc region of Japan. Distributed stretching of the arc crust resulted in the formation of most of the Japan Sea, while localized oceanic spreading at the southern termination of the eastern transpressional shear zone shaped the Japan Basin. The first oceanic crust was formed in a small triangle based on the eastern shear zone, and spreading propagated westward inside the pull-apart region. Timing of oceanic crust formation, of formation of the dextral shear zones and of block rotation in between, as well as the internal structure of the basins and the geometry of deformation along the master shear zones are used to reconstruct the opening history. This evolution is discussed by comparison to other manifestations of the arc and back arc activity, such as the history of sedimentation and volcanism. The paper then suggests that the collision of India can have tectonic consequences as far north as Japan and Sakhalin and describes the geometrical relation of back arc opening there and diffuse extrusion

Geological interpretation of volcanism and segmentation of the Mariana back-arc spreading center between 12.7°N and 18.3°N

The relationships between tectonic processes, magmatism, and hydrothermal venting along ∼600 km of the slow-spreading Mariana back-arc between 12.7°N and 18.3°N reveal a number of similarities and differences compared to slow-spreading mid-ocean ridges. Analysis of the volcanic geomorphology and structure highlights the complexity of the back-arc spreading center. Here, ridge segmentation is controlled by large-scale basement structures that appear to predate back-arc rifting. These structures also control the orientation of the chains of cross-arc volcanoes that characterize this region. Segment-scale faulting is oriented perpendicular to the spreading direction, allowing precise spreading directions to be determined. Four morphologically distinct segment types are identified: dominantly magmatic segments (Type I); magmatic segments currently undergoing tectonic extension (Type II); dominantly tectonic segments (Type III); and tectonic segments currently undergoing magmatic extension (Type IV). Variations in axial morphology (including eruption styles, neovolcanic eruption volumes, and faulting) reflect magma supply, which is locally enhanced by cross-arc volcanism associated with N-S compression along the 16.5°N and 17.0°N segments. In contrast, cross-arc seismicity is associated with N-S extension and increased faulting along the 14.5°N segment, with structures that are interpreted to be oceanic core complexes—the first with high-resolution bathymetry described in an active back-arc basin. Hydrothermal venting associated with recent magmatism has been discovered along all segment types

Einstellungen und Verhaltensweisen von Schülern auf modischem Gebiet: (Zusatzbericht zur Studie "Jugend und Mode 85")

Bei der vorliegenden Arbeit handelt es sich um empirische Untersuchungen zum Thema "Mode bei Jugendlichen". Nach einer Einleitung und einer Beschreibung des methodischen Vorgehens werden zunächst "Einstellungen und Verhaltensweisen von Schülern auf modischem Gebiet" untersucht, unterteilt ist dieses Hauptkapitel in zwei Abschnitte: "Einstellungen zur Mode" und "Realverhalten auf modischem Gebiet", die wiederum mehrfach unterteilt sind: im ersten werden "Modeinteressen, Motive für bestimmtes Modeverhalten und Quellen für modische Anregungen" behandelt, im zweiten "Reaktion auf neue Modetrends, Kaufverhalten (unter besonderer Berücksichtigung der Jugendmodeeinrichtungen), Tragegewohnheiten und Hobbytätigkeit/Selbstanfertigung". Den Abschluß bildet eine Zusammenfassung von 10 Hauptaussagen, u.a.: "Das Modeinteresse ist bei den 14- bis 17jährigen Schülern stark ausgeprägt; Hauptmotiv ist das Sich-Wohlfühlen in der eigenen Haut; erst in dritter Linie Schönheit; reichlich zwei Drittel der Befragten tragen Modeschmuck, vor allem Mädchen; Aufnäher und dergl. werden eher von Jungen getragen. Die Selbstanfertigung von Kleidungsstücken ist bei Schülern noch nicht sehr ausgeprägt." Einige Tabellen sind angehängt. (prn

Jugendklubs als spezifische Möglichkeit der Freizeitgestaltung Jugendlicher

Dieser Bericht ist Teil einer Studie "Kulturelle Aktivitäten der FDJ". Insgesamt wurden ca. 910 Jugendliche gebeten, sich zu Fragen der Jugendklubarbeit in der DDR zu äußern. "Ziel war es, Ergebnisse zu erhalten über die Zufriedenheit der Jugendlichen in Sachen Jugendklubs, ihre eigenen Aktivitäten auf diesem Gebiet." Die Ergebnisse belegen, daß für einen großen Teil der Jugendlichen der Jugendklubbesuch zu den beliebtesten Freizeittätigkeiten gehört. "71 Prozent tun dies sehr gern und gern." Etwa ein Drittel der Jugendlichen ist weiterhin der Meinung, die FDJ kümmere sich nicht ausreichend um die Belange von Jugend- bzw. Schulklubs. (psz