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1.
Conflicting water uses in coastal zones demand integrated approaches to achieve sustainable water resources management, protecting water quality while allowing those human activities which rely upon aquatic ecosystem services to thrive. This case study shows that the creation and simple management of hydraulic structures within constructed wetlands can markedly reduce the non-point pollution from agriculture and, simultaneously, benefit agricultural activities, particularly during hot and dry periods. The Vallevecchia wetland system is based on a reclaimed 900 ha-large drainage basin in Northern Italy, where droughts recently impacted agriculture causing water scarcity and saltwater intrusion. Rainwater and drained water are recirculated inside the system to limit saltwater intrusion, provide irrigation water during dry periods and reduce the agricultural nutrient loads discharged into the bordering, eutrophic Adriatic Sea. Monitoring (2003-2009) of water quality and flows highlights that the construction (ended in 2005) of a gated spillway to control the outflow, and of a 200,000 m3 basin for water storage, dramatically increased the removal of nutrients within the system. Strikingly, this improvement was achieved with a minimal management effort, e.g., each year the storage basin was filled once: a simple management of the hydraulic structures would greatly enhance the system efficiency, and store more water to irrigate and limit saltwater intrusion.  相似文献   
2.
Two of the most important biochemical hepatic pathways in the liver are those that synthesize methionine and S-adenosylmethionine (SAM) through the methylation of homocysteine. This article reviews some recent findings in this laboratory, which demonstrate that ethanol feeding to rats impairs one of these pathways involving the enzyme methionine synthetase (MS), but by way of compensation increases the activity of the enzyme betaine:homocysteine methyl transferase (BHMT), which catalyzes the second pathway in methionine and SAM biosynthesis. It has been shown that despite the inhibition of MS, the enhanced BHMT pathway utilizes hepatic betaine pools to maintain levels of SAM. Subsequent to the above findings, it has been shown that minimal supplemental dietary betaine at the 0.5% level generates SAM twofold in control animals and fivefold in ethanol-fed rats. Concomitant with the betaine-generated SAM, ethanol-induced hepatic fatty infiltration was ameliorated. In view of the fact that SAM has already been used successfully in the treatment of human maladies, including liver dysfunction, betaine, shown to protect against the early stages of alcoholic liver injury as well as being a SAM generator, may become a promising therapeutic agent and a possible alternative to expensive SAM in the treatment of liver disease and other human maladies.  相似文献   
3.
In 2 experiments with 78 female albino rats, electric stimuli applied to both pudendal nerves evoked field potentials, unit responses, and multiunit responses in the ventrolateral midbrain, in and around the peripeduncular nucleus. Bilateral lesions placed in this region suppressed sexual behavioral responses (lordosis and courting behavior) of ovariectomized Ss primed with 5, 10, 100, and 1,000 μg of estradiol benzoate and 2 mg/kg progesterone. It is proposed that the region in question represents a relay station for the integration of sensory and endocrine information concerned in the control of receptive sexual behavior in the female rat. (54 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
4.
This work is concerned with the development of different domain‐BEM (D‐BEM) approaches to the solution of two‐dimensional diffusion problems. In the first approach, the process of time marching is accomplished with a combination of the finite difference and the Houbolt methods. The second approach starts by weighting, with respect to time, the basic D‐BEM equation, under the assumption of linear and constant time variation for the temperature and for the heat flux, respectively. A constant time weighting function is adopted. The time integration reduces the order of the time derivative that appears in the domain integral; as a consequence, the initial conditions are directly taken into account. Four examples are presented to verify the applicability of the proposed approaches, and the D‐BEM results are compared with the corresponding analytical solutions.Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
5.
This work presents alternative time-marching schemes for performing elastodynamic analysis by the Boundary Element Method. The use of the static fundamental solution and the maintenance of the domain integral associated to the accelerations characterize the formulation employed in this work. It is called D-BEM, D meaning domain. Time response is obtained by employing step-by-step time-marching procedures similar to those adopted in the Finite Element Method. Among all integration procedures, Houbolt scheme became the most popular used to march in time with D-BEM formulation, in spite of the presence of a high numerical damping. In order to improve the integration, this work presents alternative schemes that can be used to perform elastodynamic analysis by the BEM with a better damping control. In order to verify the accuracy of the proposed scheme, three examples are presented and discussed at the end of this work.  相似文献   
6.
This work is concerned with the development of a D-BEM approach to the solution of 2D scalar wave propagation problems. The time-marching process can be accomplished with the use of the Houbolt method, as usual, or with the use of the Newmark method. Special attention was devoted to the development of a procedure that allows for the computation of the initial conditions contributions. In order to verify the applicability of the Newmark method and also the correctness of the expressions concerned with the computation of the initial conditions contributions, four examples are presented and the D-BEM results are compared with the corresponding analytical solutions.  相似文献   
7.
A Boundary Element Method formulation is developed for the dynamic analysis of Timoshenko beams. Based on the use of not time dependent fundamental solutions a formulation of the type called as Domain Boundary Element Method arises. Beside the typical domain integrals containing the second order time derivatives of the transverse displacement and of the rotation of the cross-section due to bending, additional domain integrals appear: one due to the loading and the other two due to the coupled differential equations that govern the problem. The time-marching employs the Houbolt method. The four usual kinds of beams that are pinned–pinned, fixed–fixed, fixed–pinned and fixed–free, under uniformly distributed, concentrated, harmonic concentrated and impulsive loading, are analyzed. The results are compared with the available analytical solutions and with those furnished by the Finite Difference Method.  相似文献   
8.
The present paper focuses on the development of a novel ExGA-based time-marching scheme applied to the scalar wave equation. The formulation of the domain boundary element method (D-BEM), characterized by the use of static fundamental solutions, preserves the domain integral of inertial terms giving rise to an equation similar to that provided by the finite element method after space discretization is carried out. This equation can be solved in time using time-stepping algorithms, such as Newmark or Houbolt methods. However, in this work Green’s functions are explicitly calculated and then incorporated into a time-marching procedure, whose results show good accuracy and stability. Two typical examples are presented to illustrate the accuracy and stability of this approach.  相似文献   
9.
In the European research project OFFICAIR, a procedure was developed to determine associations between characteristics of European offices and health and comfort of office workers, through a checklist and a self‐administered questionnaire including environmental, physiological, psychological, and social aspects. This procedure was applied in 167 office buildings in eight European countries (Portugal, Spain, Italy, Greece, France, Hungary, the Netherlands, and Finland) during the winter of 2011–2012. About 26 735 survey invitation e‐mails were sent, and 7441 office workers were included in the survey. Among respondents who rated an overall comfort less than 4 (23%), ‘noise (other than from building systems)’, air ‘too dry’, and temperature ‘too variable’ were the main complaints selected. An increase of perceived control over indoor climate was positively associated with the perceived indoor environment quality. Almost one‐third of office workers suffered from dry eyes and headache in the last 4 weeks. Physical building characteristics were associated with occupants’ overall satisfaction (acoustical solutions, mold growth, complaints procedure, cleaning activities) and health (number of occupants, lack of operable windows, presence of carpet and cleaning activities). OFFICAIR project provides a useful database to identify stressors related to indoor environmental quality and office worker's health.  相似文献   
10.
This paper carries out a discussion concerning kernels in two-dimensional BEM analysis of transient scalar wave propagation problems. Kernels obtained after performing analytical time integration are compared. An example of quadratic time variation is presented in order to illustrate some of the mathematical concepts discussed.  相似文献   
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