Wrinkling in engineering fabrics: a comparison between two different comprehensive modelling approaches

We consider two ‘comprehensive’ modelling approaches for engineering fabrics. We distinguish the two approaches using the terms ‘semi-discrete’ and ‘continuum’, reflecting their natures. We demonstrate a fitting procedure, used to identify the constitutive parameters of the continuum model from predictions of the semi-discrete model, the parameters of which are in turn fitted to experimental data. We, then, check the effectiveness of the continuum model by verifying the correspondence between semi-discrete and continuum model predictions using test cases not previously used in the identification process. Predictions of both modelling approaches are compared against full-field experimental kinematic data, obtained using stereoscopic digital image correlation techniques, and also with measured force data. Being a reduced order model and being implemented in an implicit rather than an explicit finite-element code, the continuum model requires significantly less computational power than the semi-discrete model and could therefore be used to more efficiently explore the mechanical response of engineering fabrics

An assessment of the effect of supersonic aircraft operations on the stratospheric ozone content

An assessment of the potential effect on stratospheric ozone of an advanced supersonic transport operations is presented. This assessment, which was undertaken because of NASA's desire for an up-to-date evaluation to guide programs for the development of supersonic technology and improved aircraft engine designs, uses the most recent chemical reaction rate data. From the results of the present assessment it would appear that realistic fleet sizes should not cause concern with regard to the depletion of the total ozone overburden. For example, the NOx emission of one type designed to cruise at 20 km altitude will cause the ozone overburden to increase by 0.03% to 0.12%, depending upon which vertical transport is used. These ozone changes can be compared with the predictions of a 1.74% ozone decrease (for 100 Large SST's flying at 20 km) made in 1974 by the FAA's Climatic Impact Assessment Program

Stratospheric aerosol modification by supersonic transport operations with climate implications

The potential effects on stratospheric aerosois of supersonic transport emissions of sulfur dioxide gas and submicron size soot granules are estimated. An interactive particle-gas model of the stratospheric aerosol is used to compute particle changes due to exhaust emissions, and an accurate radiation transport model is used to compute the attendant surface temperature changes. It is shown that a fleet of several hundred supersonic aircraft, operating daily at 20 km, could produce about a 20% increase in the concentration of large particles in the stratosphere. Aerosol increases of this magnitude would reduce the global surface temperature by less than 0.01 K

Integrated stratigraphy and astronomical calibration of the Serravallian/Tortonian boundary section at Monte Gibliscemi (Sicily, Italy)

Results are presented of an integrated stratigraphic (calcareous plankton biostratigraphy, cyclostratigraphy and magnetostratigraphy) study of the Serravallian=Tortonian (S=T) boundary section of Monte Gibliscemi (Sicily, Italy). Astronomical calibration of the sedimentary cycles provides absolute ages for calcareous plankton bio-events in the interval between 9.8 and 12.1 Ma. The first occurrence (FO) of Neogloboquadrina acostaensis, usually taken to delimit the S=T boundary, is dated astronomically at 11.781 Ma, pre-dating the migratory arrival of the species at low latitudes in the Atlantic by almost 2 million years. In contrast to delayed low-latitude arrival of N. acostaensis, Paragloborotalia mayeri shows a delayed low-latitude extinction of slightly more than 0.7 million years with respect to the Mediterranean (last occurrence (LO) at 10.49 Ma at Ceara Rise; LO at 11.205 Ma in the Mediterranean). The Discoaster hamatus FO, dated at 10.150 Ma, is clearly delayed with respect to the open ocean. The ages of D. kugleri first and last common occurrence (FCO and LCO), Catinaster coalitus FO, Coccolithus miopelagicus last (regular) occurrence (L(R)O) and the D. hamatus=neohamatus cross-over, however, are in good to excellent agreement with astronomically tuned ages for the same events at Ceara Rise (tropical Atlantic), suggesting that both independently established timescales are consistent with one another. The lack of a reliable magnetostratigraphy hampers a direct comparison with the geomagnetic polarity timescale of Cande and Kent (1995; CK95), but ages of calcareous nannofossil events suggests that CK95 is significantly younger over the studied time interval. Approximate astronomical ages for the polarity reversals were obtained by exporting astronomical ages of selected nannofossil events from Ceara Rise (and the Mediterranean) to eastern equatorial Pacific ODP Leg 138 Site 845, which has a reliable magnetostratigraphy. Our data from the Rio Mazzapiedi-Castellania section reveal that the base of the Tortonian stratotype corresponds almost exactly with the first regular occurrence (FRO) of N. acostaensis s.s. as defined in the present study, dated at 10.554 Ma. An extrapolated age of 11.8 Ma calculated for the top of the Serravallian stratotype indicates that there is a gap between the top of the Serravallian and the base of the Tortonian stratotype, potentially rendering all bio-events in the interval between 11.8 and 10.554 Ma suitable for delimiting the S=T boundary. Despite the tectonic deformation and the lack of a magnetostratigraphy, Gibliscemi remains a candidate to define the S=T boundary by means of the Tortonian global boundary stratotype section and point (GSSP)

A nonlinear Lagrangian particle model for grains assemblies including grain relative rotations

International audienceWe formulate a discrete Lagrangian model for a set of interacting grains, which is purely elastic. The considered degrees of freedom for each grain include placement of barycenter and rotation. Further, we limit the study to the case of planar systems. A representative grain radius is introduced to express the deformation energy to be associated to relative displacements and rotations of interacting grains. We distinguish inter‐grains elongation/compression energy from inter‐grains shear and rotations energies, and we consider an exact finite kinematics in which grain rotations are independent of grain displacements. The equilibrium configurations of the grain assembly are calculated by minimization of deformation energy for selected imposed displacements and rotations at the boundaries. Behaviours of grain assemblies arranged in regular patterns, without and with defects, and similar mechanical properties are simulated. The values of shear, rotation, and compression elastic moduli are varied to investigate the shapes and thicknesses of the layers where deformation energy, relative displacement, and rotations are concentrated. It is found that these concentration bands are close to the boundaries and in correspondence of grain voids. The obtained results question the possibility of introducing a first gradient continuum models for granular media and justify the development of both numerical and theoretical methods for including frictional, plasticity, and damage phenomena in the proposed model

Dairy production of "Saanen" goats based on meteorological variables and future climate scenarios.

Abstract: This study aimed to modeling and bioclimatic zoning of "Saanen" goat milk production in northeastern Brazil. Data were obtained from a 14-year dairy control program for 246 ?Saanen? goat matrices. Dairy production meteorological influence and mathematical modeling were assessed through statistical analyses such as Pearson?s correlation matrix and path analysis. Bioclimatic zoning for current and future scenarios, with climate changes, were delineated using inverse-square distance (ISD) and spherical model (kriging) interpolations. Results showed maximum air temperature to contribute substantially to goat dairy production; therefore, its modeling was based thereon. Current and future dairy production maps highlighted Maranhão and Piauí as regions of limited ?Saanen? milk production. Furthermore, we should emphasize that temperature rises in further scenarios may have significant impact on the potential of dairy farming for the region under study

miR-214 coordinates melanoma progression by upregulating ALCAM through TFAP2 and miR-148b downmodulation.

Malignant melanoma is one of the most aggressive human cancers, but the mechanisms governing its metastatic dissemination are not fully understood. Upregulation of miR-214 and ALCAM and the loss of TFAP2 expression have been implicated in this process, with TFAP2 a direct target of miR-214. Here, we link miR-214 and ALCAM as well as identify a core role for miR-214 in organizing melanoma metastasis. miR- 214 upregulated ALCAM, acting transcriptionally through TFAP2 and also posttranscriptionally through miR-148b (itself controlled by TFAP2), both negative regulators of ALCAM. We also identified several miR-214–mediated prometastatic functions directly promoted by ALCAM. Silencing ALCAM in miR-214–overexpressing melanoma cells reduced cell migration and invasion without affecting growth or anoikisin vitro, and it also impaired extravasation and metastasis formation in vivo. Conversely, cell migration and extravasation was reduced in miR-214–overexpressing cells by upregulation of either miR 148b or TFAP2. These findings were consistent with patterns of expression of miR-214, ALCAM, and miR-148b in human melanoma specimens. Overall, our results define a pathway involving miR-214, miR-148b, TFAP2, and ALCAM that is critical for establishing distant metastases in melanoma

Inter-annual and decadal changes in teleconnections drive continental-scale synchronization of tree reproduction

Climate teleconnections drive highly variable and synchronous seed production (masting) over large scales. Disentangling the effect of high-frequency (inter-annual variation) from low-frequency (decadal trends) components of climate oscillations will improve our understanding of masting as an ecosystem process. Using century-long observations on masting (the MASTREE database) and data on the Northern Atlantic Oscillation (NAO), we show that in the last 60 years both high-frequency summer and spring NAO, and low-frequency winter NAO components are highly correlated to continent-wide masting in European beech and Norway spruce. Relationships are weaker (non-stationary) in the early twentieth century. This finding improves our understanding on how climate variation affects large-scale synchronization of tree masting. Moreover, it supports the connection between proximate and ultimate causes of masting: indeed, large-scale features of atmospheric circulation coherently drive cues and resources for masting, as well as its evolutionary drivers, such as pollination efficiency, abundance of seed dispersers, and natural disturbance regimes

miR-214 coordinates melanoma progression by upregulating ALCAM through TFAP2 and miR-148b downmodulation

Malignant melanoma is one of the most aggressive human cancers, but the mechanisms governing its metastatic dissemination are not fully understood. Upregulation of miR-214 and ALCAM and the loss of TFAP2 expression have been implicated in this process, with TFAP2 a direct target of miR-214. Here, we link miR-214 and ALCAM as well as identify a core role for miR-214 in organizing melanoma metastasis. miR- 214 upregulated ALCAM, acting transcriptionally through TFAP2 and also posttranscriptionally through miR-148b (itself controlled by TFAP2), both negative regulators of ALCAM. We also identified several miR-214–mediated prometastatic functions directly promoted by ALCAM. Silencing ALCAM in miR-214–overexpressing melanoma cells reduced cell migration and invasion without affecting growth or anoikisin vitro, and it also impaired extravasation and metastasis formation in vivo. Conversely, cell migration and extravasation was reduced in miR-214–overexpressing cells by upregulation of either miR 148b or TFAP2. These findings were consistent with patterns of expression of miR-214, ALCAM, and miR-148b in human melanoma specimens. Overall, our results define a pathway involving miR-214, miR-148b, TFAP2, and ALCAM that is critical for establishing distant metastases in melanoma