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Vertical Cross-sections (vertical + cross-section)
Selected AbstractsFirst record of the brachiopod Lingulella waptaensis with pedicle from the Middle Cambrian Burgess ShaleACTA ZOOLOGICA, Issue 2 2010Sandra Pettersson Stolk Abstract Pettersson Stolk, S., Holmer, L. E. and Caron, J -B. 2010. First record of the brachiopod Lingulella waptaensis with pedicle from the Middle Cambrian Burgess Shale. ,Acta Zoologica (Stockholm) 91: 150,162 The organophosphatic shells of linguloid brachiopods are a common component of normal Cambrian,Ordovician shelly assemblages. Preservation of linguloid soft-part anatomy, however, is extremely rare, and restricted to a few species in Lower Cambrian Konservat Lagerstätten. Such remarkable occurrences provide unique insights into the biology and ecology of early linguloids that are not available from the study of shells alone. Based on its shells, Lingulella waptaensis Walcott, was originally described in 1924 from the Middle Cambrian Burgess Shale but despite the widespread occurrence of soft-part preservation associated with fossils from the same levels, no preserved soft parts have been reported. Lingulella waptaensis is restudied herein based on 396 specimens collected by Royal Ontario Museum field parties from the Greater Phyllopod Bed (Walcott Quarry Shale Member, British Columbia). The new specimens, including three with exceptional preservation of the pedicle, were collected in situ in discrete obrution beds. Census counts show that L. waptaensis is rare but recurrent in the Greater Phyllopod Bed, suggesting that this species might have been generalist. The wrinkled pedicle protruded posteriorly between the valves, was composed of a central coelomic space, and was slender and flexible enough to be tightly folded, suggesting a thin chitinous cuticle and underlying muscular layers. The nearly circular shell and the long, slender and highly flexible pedicle suggest that L. waptaensis lived epifaunally, probably attached to the substrate. Vertical cross-sections of the shells show that L. waptaensis possessed a virgose secondary layer, which has previously only been known from Devonian to Recent members of the Family Lingulidae. [source] Interannual variability of lower-tropospheric moisture transport during the Australian monsoonINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2002Christopher R. Godfred-Spenning Abstract The interannual variability of the horizontal lower-tropospheric moisture transport associated with the Australian summer monsoon has been analysed for the 1958,99 period. The 41-season climatology of moisture flux integrated between the surface and 450 hPa showed moderate levels of westerly transport in the month before Australian monsoon onset, associated with cross-equatorial flow in the Sulawesi Sea and west of Borneo. In the month after onset the westerly moisture transport strengthened dramatically in a zonal belt stretching from the Timor Sea to the Western Equatorial Pacific, constrained between the latitudes 5 and 15 °S, and associated with a poleward shift in the Intertropical Convergence Zone and deepening of the monsoon trough. Vertical cross-sections showed this transport extending from the surface to the 500 hPa level. In the second and third months after onset the horizontal flow pattern remained similar, although flux magnitudes progressively decreased, and the influence of trade winds became more pronounced over northern Australia. Nine El Niño and six La Niña seasons were identified from the data set, and composite plots of the affected years revealed distinct, and in some cases surprising, alterations to the large-scale moisture transport in the tropical Australian,Indonesian region. During an El Niño it was shown that the month prior to onset, in which the moisture flux was weaker than average, yielded to a dramatically stronger than average flux during the following month, with a zone of westerly flux anomalies stretching across the north Australian coast and Arafura Sea. The period of enhanced moisture flux during an El Niño is relatively short-lived, with drier easterly anomalies asserting themselves during the following 2 months, suggesting a shorter than usual monsoon period in north Australia. In the La Niña composite, the initial month after onset shows a tendency to weaker horizontal moisture transport over the Northern Territory and Western Australia. The subsequent 2 months show positive anomalies in flux magnitude over these areas; the overall effect is to prolong the monsoon. Comparison of these results with past research has led us to suggest that the tendency for stronger (weaker) circulations to arise in the initial month of El Niño (La Niña) events is a result of mesoscale changes in soil moisture anomalies on land and offshore sea surface temperature (SST) anomalies, brought about by the large-scale alterations to SST and circulation patterns during the El Niño,Southern Oscillation. The soil moisture and SST anomalies initially act to enhance (suppress) the conditions necessary for deep convection in the El Niño (La Niña) cases via changes in land,sea thermal contrast and cloud cover. Copyright © 2002 Royal Meteorological Society. [source] Eccentric cardiac hypertrophy was induced by long-term intermittent hypoxia in ratsEXPERIMENTAL PHYSIOLOGY, Issue 2 2007Li-Mien Chen It is unclear whether cardiac hypertrophy and hypertrophy-related pathways will be induced by long-term intermittent hypoxia. Thirty-six Sprague,Dawley rats were randomly assigned into three groups: normoxia, and long-term intermittent hypoxia (12% O2, 8 h per day) for 4 weeks (4WLTIH) or for 8 weeks (8WLTIH). Myocardial morphology, trophic factors and signalling pathways in the three groups were determined by heart weight index, histological analysis, Western blotting and reverse transcriptase-polymerase chain reaction from the excised left ventricle. The ratio of whole heart weight to body weight, the ratio of left ventricular weight to body weight, the gross vertical cross-section of the heart and myocardial morphological changes were increased in the 4WLTIH group and were further augmented in the 8WLTIH group. In the 4WLTIH group, tumour necrosis factor-,(TNF,), insulin-like growth factor (IGF)-II, phosphorylated p38 mitogen-activated protein kinase (P38), signal transducers and activators of transcription (STAT)-1 and STAT-3 were significantly increased in the cardiac tissues. However, in the 8WLTIH group, in addition to the above factors, interleukin-6, mitogen-activated protein kinase (MEK)5 and extracellular signal-regulated kinase (ERK)5 were significantly increased compared with the normoxia group. We conclude that cardiac hypertrophy associated with TNF, and IGF-II was induced by intermittent hypoxia. The longer duration of intermittent hypoxia further activated the eccentric hypertrophy-related pathway, as well as the interleukin 6-related MEK5,ERK5 and STAT-3 pathways, which could result in the development of cardiac dilatation and pathology. [source] Three-dimensional VP and VP,/VS models of the upper crust in the Friuli area (northeastern Italy)GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2000G. F. Gentile 3-D images of P velocity and P - to S -velocity ratio have been produced for the upper crust of the Friuli area (northeastern Italy) using local earthquake tomography. The data consist of 2565 P and 930 S arrival times of high quality. The best-fitting VP and VP,/VS 1-D models were computed before the 3-D inversion. VP was measured on two rock samples representative of the investigated upper layers of the Friuli crust. The tomographic VP model was used for modelling the gravity anomalies, by converting the velocity values into densities along three vertical cross-sections. The computed gravity anomalies were optimized with respect to the observed gravity anomalies. The crust investigated is characterized by sharp lateral and deep VP and VP,/VS anomalies that are associated with the complex geological structure. High VP,/VS values are associated with highly fractured zones related to the main faulting pattern. The relocated seismicity is generally associated with sharp variations in the VP,/VS anomalies. The VP images show a high-velocity body below 6 km depth in the central part of the Friuli area, marked also by strong VP,/VS heterogeneities, and this is interpreted as a tectonic wedge. Comparison with the distribution of earthquakes supports the hypothesis that the tectonic wedge controls most of the seismicity and can be considered to be the main seismogenic zone in the Friuli area. [source] In search of zonal circulations in the equatorial Atlantic sector from the NCEP,NCAR reanalysisINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 1 2001Stefan Hastenrath Abstract The National Center for Environmental Prediction,National Center for Atmospheric Research (NCEP,NCAR) 1958,1997 upper-air dataset has been evaluated for evidence of equatorial zonal circulation cells over the Atlantic and adjacent continents. For January, April, July and October, maps are presented of mid-tropospheric vertical motion, upper-tropospheric divergent flow, and zonal,vertical cross-sections of vertical and divergent zonal motion and total zonal flow. In the boreal winter half-year, a centre of intense ascending motion and upper-tropospheric, mainly northward-directed outflow is located off the mouth of the Amazon. From this centre there is also some outflow into centres of upper-tropospheric convergence and subsidence over the equatorial eastern Pacific and eastern Atlantic, respectively. From January to April, the near-equatorial band of ascending motion shifts southward, and the upper-tropospheric convergence centre is displaced from the Equator into the South Atlantic. In the boreal summer half-year, the band of strongest ascending motion is displaced northward, and two separate centres of upper-tropospheric divergent outflow are found over northern hemispheric Africa and the Central American Seas. From these centres, the outflow is directed approximately southward into the southern hemisphere. The analysis points to the existence of an equatorial zonal circulation cell in the Atlantic sector confined to around January. Copyright © 2001 Royal Meteorological Society [source] Complex behavioural pattern as an aid to identify the producer of Zoophycos from the Middle Permian of OmanLETHAIA, Issue 2 2009DIRK KNAUST The trace fossil Zoophycos is abundant in transgressive, shallow marine carbonates in the Middle Permian (Wordian) Khuff Formation of the Huqf-Haushi Uplift of Interior Oman. It often occurs as part of a complex (compound) trace fossil that comprises two integrated elements: (i) irregular galleries with straight to gently curved tunnels and interconnected shafts, and (ii) simple planar to complex spreiten structures with a marginal tube (Zoophycos). The galleries are characterized by irregularly winding, dichotomous branching, large variation in shape and size and circular to elliptical vertical cross-sections. Zoophycos consists of spreiten with a marginal tube, either originating as a simple lobe from the convex segment of a curved tunnel, or forming more complex, subcircular, spreiten systems parallel to bedding. The spreiten were formed by simple strip mining, where the animal defecated without producing faecal pellets. U-shaped marginal tubes indicate that the burrows were well aerated. The complex trace fossil points to combined dwelling and deposit-feeding behaviour, with irregular galleries in the firm substrate and Zoophycos spreiten in the softground below it. It can be assumed that the animal used the open tunnel system mainly for dwelling (domichnion) and possibly suspension feeding, but occasionally changed to deposit feeding while creating the spreiten (fodinichnion). The integration of the irregular galleries (tunnels and interconnected shafts) with the marginal tubes of Zoophycos suggests the same producer for this compound trace fossil. Many modern polychaetes produce very similar galleries within firm and soft substrates, and polychaetes are therefore interpreted as the most likely producers. Similarities between Permian and Triassic Zoophycos suggest comparable trace making behaviour before and after the end-Permian mass extinction. [source] The physical scale modelling of braided alluvial architecture and estimation of subsurface permeabilityBASIN RESEARCH, Issue 3 2002D. J. Moreton ABSTRACT The quantitative modelling of fluvial reservoirs, especially in the stages of enhanced oil recovery, requires detailed three-dimensional data at both the scale of the channel belt and within-channel. Although studies from core, analogue outcrop and modern environments may partially meet these needs, they often cannot provide detail on the smaller-scale (i.e. channel-scale) heterogeneity, frequently suffer from limited three-dimensional exposure and cannot be used to examine the influence of different variables on the process,deposit relationship. Physical modelling offers a complementary technique that can address many of these quantitative requirements and holds great future potential for integration with reservoir modelling. Physical modelling provides the potential to upscale results and derive reservoir information on three-dimensional facies geometry, connectivity and permeability. This paper describes the development and use of physical modelling, which employs generic Froude-scaling principles, in an experimental basin that permits aggradation in order to model the morphology and subsurface depositional stratigraphy of coarse-grained braided rivers. An example is presented of a 1:50 scale model based on the braided Ashburton River, Canterbury Plains, New Zealand and the adjacent late Quaternary braided alluvium exposed in the coastal cliffs. Critically, a full, bimodal grain size distribution (20% sand and 80% gravel) was used to replicate the prototype, which allows the realistic reproduction of the surface morphology and importantly permits grain size sorting during deposition. Uncertainties associated with the compression of time, sediment mass balance and the hydrodynamics of the finest particle sizes do not appear to affect the reproducibility of stratigraphy between experimental and natural environments. Sectioning of the preserved sedimentary sequence in the physical model allows quantification of the geometry, shape, spatial distribution and internal sedimentary structure of the coarse- and fine-grained facies. A six-fold facies scheme is proposed for the model braided alluvium and a direct link is established between the grain size distribution and facies type: this allows permeability to be estimated for each facies, which can be mapped onto two-dimensional vertical cross-sections of the preserved stratigraphy. Results demonstrate the dominance of four facies based on permeability that range over three orders of magnitude in hydraulic conductivity. Quantification of such variability, and linkage to both vertical proportion curves for facies distribution and connectivity presents significant advantages over other methodologies and offers great potential for the modelling of heterogeneous braided river sediments at the within channel-belt scale. This paper outlines how physical models may be used to develop high-resolution, geologically-accurate, object-based reservoir simulation models. [source] | |||||||||||||