13,737 research outputs found
The Impacts of WTO and Water Policy Changes on Saudi Arabian Agriculture: Results from an Equilibrium Displacement Model
Saudi Arabia's food consumption has grown dramatically over time. There has been a sharp increase in food consumption and significant changes in the composition of food consumed. Therefore, it is important that the government of Saudi Arabia anticipate further effects of these changes on growth of food demand and focus on food policies that contribute to development goals. On the other hand, limited agricultural productivity and the nature of the country's climatic conditions have constrained agricultural production. This restricted growth in production, combined with population growth, has led Saudi Arabia to depend heavily on food imports to cover the gap between domestic demand and local production. The increased reliance on imports as a source of food will increase the country's import demand. These main problems facing the Saudi agricultural sector suggest the need for an analytical framework that can evaluate effects of policy and resource change on imports, local production and local demand simultaneously. Ideally, the framework should account for substitution and income effects across products that might arise from changes in consumption and production patterns. This is the main objective of this paper.Food Consumption/Nutrition/Food Safety,
Modelling and Optimising of a Light-Weight Rockfall Catch Fence System
Rockfall catch fence is a mechanical barrier system that is used at the foot of cliffs to stop and retain falling rocks from reaching nearby infrastructures. A typical system comprises of a high tensile strength wire mesh that is anchored to the ground by rigid posts and strengthened to the lateral and upslope sides by anchoring tension cables. Additional components, such as shock absorbers, might be added to improve the system capacity to dissipate energy. This multi-component system characterises by geometrical complexity and high nonlinear response to impact loads.
A light-weight catch fence system is a simple system that can be easily installed in a time efficient manner using manpower rather than heavy machinery, which makes it ideal for railways located in mountainous and difficult terrain regions where there is difficulty in accessing sites with limited workspaces and restricted installation times. However, this should be combined with a proper design to ensure that the system provides the required protection to impede falling rocks from reaching the train lines. In this paper, a parametric study based on finite element analysis is developed to optimise the design of a light-weight catch fence system that has an energy absorption capacity of up to 100 kJ
Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI
BACKGROUND:
Coronary revascularization guided by fractional flow reserve (FFR) is associated with better patient outcomes after the procedure than revascularization guided by angiography alone. It is unknown whether the instantaneous wave-free ratio (iFR), an alternative measure that does not require the administration of adenosine, will offer benefits similar to those of FFR.
METHODS:
We randomly assigned 2492 patients with coronary artery disease, in a 1:1 ratio, to undergo either iFR-guided or FFR-guided coronary revascularization. The primary end point was the 1-year risk of major adverse cardiac events, which were a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization. The trial was designed to show the noninferiority of iFR to FFR, with a margin of 3.4 percentage points for the difference in risk.
RESULTS:
At 1 year, the primary end point had occurred in 78 of 1148 patients (6.8%) in the iFR group and in 83 of 1182 patients (7.0%) in the FFR group (difference in risk, -0.2 percentage points; 95% confidence interval [CI], -2.3 to 1.8; P<0.001 for noninferiority; hazard ratio, 0.95; 95% CI, 0.68 to 1.33; P=0.78). The risk of each component of the primary end point and of death from cardiovascular or noncardiovascular causes did not differ significantly between the groups. The number of patients who had adverse procedural symptoms and clinical signs was significantly lower in the iFR group than in the FFR group (39 patients [3.1%] vs. 385 patients [30.8%], P<0.001), and the median procedural time was significantly shorter (40.5 minutes vs. 45.0 minutes, P=0.001).
CONCLUSIONS:
Coronary revascularization guided by iFR was noninferior to revascularization guided by FFR with respect to the risk of major adverse cardiac events at 1 year. The rate of adverse procedural signs and symptoms was lower and the procedural time was shorter with iFR than with FFR. (Funded by Philips Volcano; DEFINE-FLAIR ClinicalTrials.gov number, NCT02053038 .)info:eu-repo/semantics/publishedVersio
Controller Design for Active Suspension System of 1⁄4 Car with Unknown Mass and Time-Delay
—The purpose of this paper is to present a modeling and
control of a quarter-car active suspension system with unknown
mass, unknown time-delay and road disturbance. The objective of
designing the controller is to derive a control law to achieve stability
of the system and convergence that can considerably improve ride
comfort and road disturbance handling. This is accomplished by
using Routh-Hurwitz criterion based on defined parameters.
Mathematical proof is given to show the ability of the designed
controller to ensure the target of design, implementation with the
active suspension system and enhancement dispersion oscillation of
the system despite these problems. Simulations were also performed
to control quarter car suspension, where the results obtained from
these simulations verify the validity of the proposed design
Pion and Kaon Decay Constants: Lattice vs. Resonance Chiral Theory
The Lattice results for the pion and kaon decay constants are analysed within
the Resonance Chiral Theory framework in the large NC limit. The approximately
linear behaviour of the observable at large light-quark mass is explained
through the interaction with the lightest multiplet of scalar resonances. The
analysis of the Lattice results allows to obtain the resonance mass MS=1049 +-
25 MeV and the Chiral Perturbation Theory parameters at leading order in 1/NC.Comment: 10 pages, 2 figure
Electron Glass Dynamics
Examples of glasses are abundant, yet it remains one of the phases of matter
whose understanding is very elusive. In recent years, remarkable experiments
have been performed on the dynamical aspects of glasses. Electron glasses offer
a particularly good example of the 'trademarks' of glassy behavior, such as
aging and slow relaxations. In this work we review the experimental literature
on electron glasses, as well as the local mean-field theoretical framework put
forward in recent years to understand some of these results. We also present
novel theoretical results explaining the periodic aging experiment.Comment: Invited review to appear in Annual Review of Condensed Matter Physic
Controller design for active suspension system of ¼ car with unknown mass and time-delay
—The purpose of this paper is to present a modeling and
control of a quarter-car active suspension system with unknown
mass, unknown time-delay and road disturbance. The objective of
designing the controller is to derive a control law to achieve stability
of the system and convergence that can considerably improve ride
comfort and road disturbance handling. This is accomplished by
using Routh-Hurwitz criterion based on defined parameters.
Mathematical proof is given to show the ability of the designed
controller to ensure the target of design, implementation with the
active suspension system and enhancement dispersion oscillation of
the system despite these problems. Simulations were also performed
to control quarter car suspension, where the results obtained from
these simulations verify the validity of the proposed design
Functional correlates of positional and gender-specific renal asymmetry in drosophila
Accordingly, the physical asymmetry of the tubules in the body cavity is directly adaptive. Now that the detailed machinery underlying internal asymmetry is starting to be delineated, our work invites the investigation, not just of tissues in isolation, but in the context of their unique physical locations and milieux
Climate‐induced changes in the suitable habitat of cold‐water corals and commercially important deep‐sea fishes in the North Atlantic
The deep sea plays a critical role in global climate regulation through uptake and storage of heat and carbon dioxide. However, this regulating service causes warming, acidification and deoxygenation of deep waters, leading to decreased food availability at the seafloor. These changes and their projections are likely to affect productivity, biodiversity and distributions of deep‐sea fauna, thereby compromising key ecosystem services. Understanding how climate change can lead to shifts in deep‐sea species distributions is critically important in developing management measures. We used environmental niche modelling along with the best available species occurrence data and environmental parameters to model habitat suitability for key cold‐water coral and commercially important deep‐sea fish species under present‐day (1951–2000) environmental conditions and to project changes under severe, high emissions future (2081–2100) climate projections (RCP8.5 scenario) for the North Atlantic Ocean. Our models projected a decrease of 28%–100% in suitable habitat for cold‐water corals and a shift in suitable habitat for deep‐sea fishes of 2.0°–9.9° towards higher latitudes. The largest reductions in suitable habitat were projected for the scleractinian coral Lophelia pertusa and the octocoral Paragorgia arborea, with declines of at least 79% and 99% respectively. We projected the expansion of suitable habitat by 2100 only for the fishesHelicolenus dactylopterus and Sebastes mentella (20%–30%), mostly through northern latitudinal range expansion. Our results projected limited climate refugia locations in the North Atlantic by 2100 for scleractinian corals (30%–42% of present‐day suitable habitat), even smaller refugia locations for the octocorals Acanella arbuscula and Acanthogorgia armata (6%–14%), and almost no refugia for P. arborea. Our results emphasize the need to understand how anticipated climate change will affect the distribution of deep‐sea species including commercially important fishes and foundation species, and highlight the importance of identifying and preserving climate refugia for a range of area‐based planning and management tools
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