Actes de la première conférence régionale sur la lutte contre Miconia = Proceedings of the first regional conference on Miconia control

#Miconia Calvescens DC (Melastomataceae) est un arbre originaire des forêts humides d'Amérique tropicale, introduit comme plante ornementale en Polynésie Française et dans les îles Hawaï où il y constitue actuellement une plante envahissante majeure et y a été déclaré légalement espèce nuisible. Les objectifs de cette première conférence régionale sur la lutte contre #M. calvescens réunissant chercheurs et gestionnaires, sont de présenter le statut et la distribution actuelle de cette peste végétale dans les différentes zones envahies de la région du Pacifique (Polynésie Française, Hawaï, Australie), les méthodes de lutte déjà utilisées (lutte manuelle, chimique et biologique) ainsi que les stratégies de gestion appliquée

Calculating pH from EC and SAR values in salinity models and SAR from soil and bore water pH and EC data

Currently used soil salinity models do not contain a mechanism for including exchangeable sodium effects on soil pH. A method is needed that allows pH calculation from the sodium adsorption ratio (SAR) or exchangeable sodium percentage (ESP) and electrical conductivity (EC) data. This study developed a simple method for calculating saturated soil paste and aqueous solution pH from SAR (or ESP) and EC data and compared the results with measured values from a number of soils and subsurface waters. The equation pH - A+{B*(SAR)^1/2 /(1+C*EC)} estimated soil pH from EC and SAR or ESP values. When rewritten as: SAR or ESP = {(pH-A)(1+C*EC)/B}^2 , the SAR or ESP was estimated from pH and EC data. By using shallow bore (well) water and soil extract data from the Murray Basin, values were determined for the scalar terms A, B and C. These values differed among subsurface water and soil types, however, the range of each scalar was reasonably small. It was found that a range of at least 2 - 5 pH units in the calibration data was necessary to obtain reliable regression between predicted and measured pH and SAR or ESP values. When these conditions were met, the predicted results were satisfactory. These relationships provide a method for pH calculation in soil salinity models which takes into account soil EC and sodium effects. They also provide a rapid field method to estimate SAR or ESP from easily obtainable EC and pH data. Further research is needed to define the factors that determine the values of A, B and C

The Optical Model Analysis of 200 MeV p + 16-O Elastic Scattering

This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit

Purifying and Reversible Physical Processes

Starting from the observation that reversible processes cannot increase the purity of any input state, we study deterministic physical processes, which map a set of states to a set of pure states. Such a process must map any state to the same pure output, if purity is demanded for the input set of all states. But otherwise, when the input set is restricted, it is possible to find non-trivial purifying processes. For the most restricted case of only two input states, we completely characterize the output of any such map. We furthermore consider maps, which combine the property of purity and reversibility on a set of states, and we derive necessary and sufficient conditions on sets, which permit such processes.Comment: 5 pages, no figures, v2: only minimal change

Understanding salt and sodium in soils, irrigation water and shallow groundwaters: A companion to the software program SWAGMAN-Whatif

Understanding Salt and Sodium in Soils, Irrigation Water and Shallow Groundwaters is a companion booklet to SWAGMANe-Whatif, a computer model that lets you see how salts, soils, water and water tables interact. SWAGMANkWhatif also lets you assess the effects of management practices that you might undertake in a particular area. This booklet gives background information to help you understand salts, sodium and their interactions with water and soils. It explains where sodium and salts come from, how to identify salt-affected soils, and gives instructions on taking soil and water samples for analysis. It also gives suggestions on how to reduce the harmful effects of salts and sodium, and tells you where to get advice in making reclamation and management decisions for each situation. Managing salt and sodium affected soils, together with waters used for irrigation, is complex. It is not possible to cover all technical aspects or possible treatment approaches in this booklet. Instead, we have given a simple overview of the major principles involved in diagnosing and managing salt and sodium affected soils and irrigation waters. It is difficult to summarise salt and sodium effects on soils and plants without using some technical terms, so a comprehensive glossary has been included

SWAGMAN-Whatif, an interactive computer program to teach salinity relationships in irrigated agriculture

Managing salt-affected irrigated lands and marginally salinine irrigation water requires understanding the interactions among soil salinity, crop salt tolerances, soil physical properties, irrigation water quality, irrigation management, water table depth and quality, climate, and crop yield. An interactive computer program was developed to simulate interactions among the above factors. It shows how changing one factor impacts the others for a growing season. The user selects a climate, crop, and soil characteristics from menu lists, then sets the water table depth and quality, irrigation water quality, and develops an irrigation schedule. On execution, surface runoff, water table rise or fall, and the relative yield reductions due to overirrigation, underirrigation, and salinity are shown numerically for 1 yr. Soil water content, soil salinity, water table depth changes, and rain and irrigation events are also shown graphically. An IBM-compatible computer with a math coprocessor executes the program in 6 to 10 s. This is an educational tool designed to teach the concepts of salinity and irrigation management and is not an irrigation scheduling program nor a management tool. Two versions have been developed, one using metric units, southern hemisphere growing seasons, and Australian terminology; and a second using northern hemisphere growing seasons and U.S. units and terminology. The U.S. version also allows use of metric units. The program is supplied in executable code with a user guide, a soil salinity manual, and a salinity units conversion slide rule

Predicting salinization in a heavy clay soil subjected to a saline shallow water table

Salt increase in a heavy clay soil due to capillary rise was simulated by an analytical model and a numerical model. Predicted values were compared with experimental data. The analytical model was inadequate in predicting salinisation in a dynamic crop/soil system. When root growth was accounted for, the numerical model satisfactorily predicted salt increase in the soil profile

A Lanczos algorithm for linear response

An iterative algorithm is presented for solving the RPA equations of linear response. The method optimally computes the energy-weighted moments of the strength function, allowing one to match the computational effort to the intrinsic accuracy of the basic mean-field approximation, avoiding the problem of solving very large matrices. For local interactions, the computational effort for the method scales with the number of particles N_p as O(N_p^3).Comment: 12 pages including 3 figures; Late

Models for estimating capillary rise in a heavy clay soil with a saline shallow water table

Shallow saline water tables underlie large areas of the clay soils in the Murray basin of Australia. Accurate estimation of capillary rise is important in formulating management strategies to avoid degradation of such soils. Measured capillary rise from a saline water table was compared with capillary rise estimated by three mathematical models of varying complexity and input requirement. A quasi steady state analytical model (QSSAM), a transient state analytical model (TSAM) and a numerical model (NM) were used. An undisturbed heavy clay soil core of 0.75 m diameter and 1.4 m deep was subjected to a static saline water table at 1.2 m from the surface. A wheat crop was grown on the core and the weekly capillary rise from the water table was measured. The electrical conductivity of a 1 : 2 soil : water extract was determined at 0.15 m depth intervals before and 21 weeks after the introduction of the saline water table. The QSSAM did not satisfactorily estimate the initial wetting of the subsoil and the estimated capillary rise was considerably lower than the measured values. Capillary rise estimated by the TSAM was reasonably close to the measured values, but the weekly rates fluctuated considerably. The NM estimated capillary rise quite satisfactorily throughout the experiment. Except near the soil surface, the electrical conductivity values estimated by the NM were close to the measured values. For estimating total capillary rise over large areas, the TSAM is preferred over the NM because of its fewer input requirements and shorter execution time

Large-Angle Proton-Nucleus Elastic Scattering

This work was supported by the National Science Foundation Grants NSF PHY 78-22774 A03, NSF PHY 81-14339, and by Indiana Universit