2,818 research outputs found
Globalization and Traceability of Agricultural Production: The Role of Mechanization
Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is an Invited Paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 4 (2002): F. Pierce and R. Cavalieri. Globalization and Traceability of Agricultural Production: The Role of Mechanization. Club of Bologna. Vol. IV. September 2002
Seismic risk of infrastructure systems with treatment of and sensitivity to epistemic uncertainty
Modern society’s very existence is tied to the proper and reliable functioning of its Critical Infrastructure (CI) systems. In the seismic risk assessment of an infrastructure, taking into account all the relevant uncertainties affecting the problem is crucial. While both aleatory and epistemic uncertainties affect the estimate of seismic risk to an infrastructure and should be considered, the focus herein is on the latter. After providing an up-to-date literature review about the treatment of and sensitivity to epistemic uncertainty, this paper presents a comprehensive framework for seismic risk assessment of interdependent spatially distributed infrastructure systems that accounts for both aleatory and epistemic uncertainties and provides confidence in the estimate, as well as sensitivity of uncertainty in the output to the components of epistemic uncertainty in the input. The logic tree approach is used for the treatment of epistemic uncertainty and for the sensitivity analysis, whose results are presented through tornado diagrams. Sensitivity is also evaluated by elaborating the logic tree results through weighted ANOVA. The formulation is general and can be applied to risk assessment problems involving not only infrastructural but also structural systems. The presented methodology was implemented into an open-source software, OOFIMS, and applied to a synthetic city composed of buildings and a gas network and subjected to seismic hazard. The gas system’s performance is assessed through a flow-based analysis. The seismic hazard, the vulnerability assessment and the evaluation of the gas system’s operational state are addressed with a simulation-based approach. The presence of two systems (buildings and gas network) proves the capability to handle system interdependencies and highlights that uncertainty in models/parameters related to one system can affect uncertainty in the output related to dependent systems
Diversification of spatiotemporal expression and copy number variation of the echinoid hbox12/pmar1/micro1 multigene family
Changes occurring during evolution in the cis-regulatory landscapes of individual members of multigene families might impart diversification in their spatiotemporal expression and function. The archetypal member of the echinoid hbox12/pmar1/micro1 family is hbox12-a, a homeobox-containing gene expressed exclusively by dorsal blastomeres, where it governs the dorsal/ventral gene regulatory network during embryogenesis of the sea urchin Paracentrotus lividus. Here we describe the inventory of the hbox12/pmar1/micro1 genes in P. lividus, highlighting that gene copy number variation occurs across individual sea urchins of the same species. We show that the various hbox12/pmar1/micro1 genes group into three subfamilies according to their spatiotemporal expression, which ranges from broad transcription throughout development to transient expression in either the animal hemisphere or micromeres of the early embryo. Interestingly, the promoter regions of those genes showing comparable expression patterns are highly similar, while differing from those of the other subfamilies. Strikingly, phylogenetic analysis suggests that the hbox12/pmar1/micro1 genes are species-specific, exhibiting extensive divergence in their noncoding, but not in their coding, sequences across three distinct sea urchin species. In spite of this, two micromere-specific genes of P. lividus possess a TCF/LEF-binding motif in a similar position, and their transcription relies on Wnt/
f-catenin signaling, similar to the pmar1 and micro1 genes, which in other sea urchin species are involved in micromere specification. Altogether, our findings suggest that the hbox12/pmar1/micro1 gene family evolved rather rapidly, generating paralogs whose cis-regulatory sequences diverged following multiple rounds of duplication from a common ancestor
The correlation of VLF propagation variations with atmospheric planetary-scale waves
Variations in the received daytime phase of long distance, cesium-controlled, VLF transmission were compared to the height variations of the 10-mb isobaric surface during the first three months of 1965 and 1969. The VLF phase values are also compared to height variations of constant electron densities in the E-region and to variations of f-min which have been shown to be well correlated with planetary-scale variations in the stratosphere by Deland and Cavalieri (1973). The VLF phase variations show good correlation with these previous ionospheric measurements and with the 10-mb surfaces. The planetary scale waves in the stratosphere are shown to be travelling on the average eastward in 1965 and westward in 1969. These correlations are interpreted as due to the propagation of travelling planetary scale waves with westward tilted wave fronts. Upward energy transport due to the vertical structure of those waves is also discussed. These correlations provide further evidence for the coupling between the lower ionosphere at about 70 km altitude (the daytime VLF reflection height and the stratosphere, and they demonstrate the importance of planetary wave phenomena to VLF propagation
Some Natural History Notes on the Brooding Behavior and Social System of Two Oklahoma Skinks, Plestiodon fasciatus and Plestiodon obtusirostris
The purpose of this study was to quantify the social and reproductive behavior of Plestiodon fasciatus and P. obtusirostris. We conducted laboratory experiments with brooding behavior and field experiments to test for mate-guarding and territoriality. To determine the use of space by both species, we conducted a mark-recapture study. We constructed two permanent 1-ha trapping grids of can pitfall traps and cover-boards, with an inter-trap distance of 10 m. One was in a mixed woodland-grassland habitat and one in a grassland habitat. We manipulated the hydric environment to determine parental behavior of brooding female P. obtusirostris. We size-matched male P. fasciatus and P. obtusirostris for dyadic encounters with and without females and both on and off home ranges in order to determine social behavior. Change in hydric conditions did not induce female P. obtusirostris to move eggs to more suitable nest sites in our experiments. Plestiodon fasciatus exhibited behavior associated with mate-guarding. Plestiodon obtusirostris did not display behavior associated with territoriality, and our experiment examining mate-guarding calls for a more intensive study
Some Natural History Notes on the Brooding Behavior and Social System of Two Oklahoma Skinks, Plestiodon fasciatus and Plestiodon obtusirostris
The purpose of this study was to quantify the social and reproductive behavior of Plestiodon fasciatus and P. obtusirostris. We conducted laboratory experiments with brooding behavior and field experiments to test for mate-guarding and territoriality. To determine the use of space by both species, we conducted a mark-recapture study. We constructed two permanent 1-ha trapping grids of can pitfall traps and cover-boards, with an inter-trap distance of 10 m. One was in a mixed woodland-grassland habitat and one in a grassland habitat. We manipulated the hydric environment to determine parental behavior of brooding female P. obtusirostris. We size-matched male P. fasciatus and P. obtusirostris for dyadic encounters with and without females and both on and off home ranges in order to determine social behavior. Change in hydric conditions did not induce female P. obtusirostris to move eggs to more suitable nest sites in our experiments. Plestiodon fasciatus exhibited behavior associated with mate-guarding. Plestiodon obtusirostris did not display behavior associated with territoriality, and our experiment examining mate-guarding calls for a more intensive study
Coherent pressure structures in turbulent channel flow
Most of the studies on pressure fluctuations in wall-bounded turbulent flows
aim at obtaining statistics as power spectra and scaling laws, especially at
the walls. In the present study we study energetic coherent pressure structures
of turbulent channel flows, aiming at a characterization of dominant coherent
structures throughout the channel. Coherent structures are detected using
spectral proper orthogonal decomposition (SPOD) and modeled using resolvent
analysis, similar to related works dealing with velocity fluctuations, but
using pressure fluctuations as the output of interest. The resolvent operator
was considered with and without the Cess eddy viscosity model. Direct numerical
simulations (DNSs) of incompressible turbulent channel flows at friction
Reynolds numbers of approximately 180 and 550 were employed as databases. Three
representative dominant structures emerged from a preliminary spectral
analysis: near-wall, large-scale and spanwise-coherent structures. For
frequency-wavenumber combinations corresponding to these three representative
structures, SPOD results show a strong dominance of the leading mode,
highlighting low-rank behavior of pressure fluctuations. The leading resolvent
mode closely agrees with the first SPOD mode, providing support to studies that
showed better performance of resolvent-based estimators when predicting
pressure fluctuations compared to velocity fluctuations. The dominant
mechanisms of the analyzed modes are seen to be the generation of
quasi-streamwise vortices with pressure fluctuations appearing close to vortex
centers. A study on the individual contributions of the nonlinear terms
(treated as forcing in resolvent analysis) to the pressure output reveals that
each forcing component plays a constructive role to the input-output
formulation, which also helps understanding the weaker role of forcing color in
driving pressure fluctuations.Comment: 24 pages, 23 figure
On the applicability of transfer function models for ssi embedment effects
Soil-structure interaction (SSI) effects are typically neglected for relatively lightweight buildings that are less than two-three storeys high with a limited footprint area and resting on shallow foundations (i.e., not featuring a basement). However, when the above conditions are not satisfied, and in particular when large basements are present, important kinematic SSI may develop, causing the foundation-level motion to deviate from the free-field one due to embedment effects. In the literature, transfer function models that estimate the filtering effect induced by rigid massless embedded foundations are available to “transform” foundation-level recordings into free-field ones, and vice-versa. This work describes therefore a numerical study aimed at assessing potential limits of the applicability of such transfer functions through the employment of a 3D nonlinear soil-block model representing a layered soil, recently developed and validated by the authors, and featuring on top a large heavy building with basement. A number of finite element site response analyses were carried out for different seismic input signals, soil profiles and embedment depths of the building’s basement. The numerically obtained transfer functions were compared with the curves derived using two analytical models. It was observed that the latter are able to reliably predict the embedment effects in “idealised” soil/input conditions under which they have been developed. However, in real conditions, namely when a non-homogeneous profile with nonlinear behaviour under a given seismic excitation is considered, especially in presence of a basement that is more than one storey high, they may fail in capturing some features, such as the frequency-dependent amplification of the motion at the basement level of a building with respect to the free-field one
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