Analyses of silicon dioxide, magnesium oxide, lead fluoride, bismuth as low-pass velocity filters for neutrons

Transmission measurement of neutrons by filter materials for low energy neutrons is important for the study of structure and dynamics of condensed matter. Since only thermal neutrons are useful for such experiments, filter materials that transmit thermal neutrons while attenuating fast neutrons and gamma rays are of considerable interest

Complex Adaptive System Modelling of River Murray Salinity Policy Options

This paper reports on complex adaptive system (CAS) simulation of the River Murray Basin in Australia to compare capacity of institutional options to maintain functioning of key river system within a "bandwidth" that limits irreversible system state changes and highly adverse consequences. The modelling framework characterise diverse irrigation agents who profit from water diversion and cause external salinity impacts, water and salt process that form the link between irrigator actions and agricultural profits and external costs, and a river manager who sets institutional rules. Emphasis is on the CAS nature of the system and on institutional rules to accommodate choosing actions differently based on con dition of the system has been referred to as state contingent management (Wills, 2003) or threshold based management (Roe and Van Eeten, 2001). Key findings are that policy focus on the source of salinity by reducing drainage are much more cost effective than strategies to mitigate salinity once it occurs and that state contingent dilution provision when it has high benefit and low opportunity cost is also a cost effective way to manage salinity.Resource /Energy Economics and Policy,

Few-Boson Processes in the Presence of an Attractive Impurity under One-Dimensional Confinement

We consider a few-boson system confined to one dimension with a single distinguishable particle of lesser mass. All particle interactions are modeled with $\delta$-functions, but due to the mass imbalance the problem is nonintegrable. Universal few-body binding energies, atom-dimer and atom-trimer scattering lengths are all calculated in terms of two parameters, namely the mass ratio: $m_{\text{L}}/m_{\text{H}}$, and ratio $g_{\text{HH}}/g_{\text{HL}}$ of the $\delta$-function couplings. We specifically identify the values of these ratios for which the atom-dimer or atom-trimer scattering lengths vanish or diverge. We identify regions in this parameter space in which various few-body inelastic process become energetically allowed. In the Tonks-Girardeau limit ($g_{\text{HH}}\rightarrow \infty$), our results are relevant to experiments involving trapped fermions with an impurity atom

Optimal co-adapted coupling for the symmetric random walk on the hypercube

Let X and Y be two simple symmetric continuous-time random walks on the vertices of the n-dimensional hypercube, Z2n. We consider the class of co-adapted couplings of these processes, and describe an intuitive coupling which is shown to be the fastest in this class

ECONOMIC FORCES INFLUENCING VALUE-ADDED FOOD INDUSTRIES: IMPLICATIONS FOR SOUTHERN AGRICULTURE

Agribusiness,

Susceptibility of White Spruce Seed Sources to Yellowheaded Spruce Sawfly, \u3ci\u3ePikonema Alaskensis,\u3c/i\u3e(Hymenoptera: Tenthredinidae)

A field caging technique was used to test the susceptibility of 25 white spruce, Picea glauca (Moench) Voss, seed sources to attack by Pikonema alaskensis (Rohwer). No sig- nificant differences were found in the number of eggs laid, number of dessicated eggs, or number of egg slits. Percent oviposition differed significantly within a tree, the south side having more eggs. Bud size differed significantly within trees and between trees but not between seed sources. The number of sawfly eggs laid on a bud could not be related to bud size. There was no significant difference in susceptibility of the seed sources studied to Pikonema alaskensis

The effect of a period of water shortage on the growth and yield of cassava

Drought stress was imposed on 2 cassava cv. (M Col 22 and M Mex 59) at Santander de Quilichao (Colombia), by withholding rainfall from field plots (plastic covers were placed over the soil surface) for 10 wk, commencing when crops were 12 wk old. The plants were then allowed to recuperate until the expt was terminated at 10 mo. Harvests were taken at intervals through the growth cycle and were supplemented with measurements of fine root distribution, leaf production and senescence, soil and plant water status, and stomatal response. As a result of the stress, the late-developing cv. M Mex 59 actually improved its yield at 10 mo over the controls. An explanation for the behavior of both cv. is sought in the relative effects of water shortage on DM production and allocation, canopy dynamics and internal plant water relations. (AS)Se impuso estres de sequia en 2 cv. de yuca (M Col 22 y M Mex 59) mediante el impedimento de lluvias en las parcelas (se colocaron cobertores plasticos sobre la superficie del suelo) durante 10 semanas en Santander de Quilichao (Colombia), comenzando cuando los cultivos tenian 12 semanas; luego se permitio la recuperacion de las plantas, hasta que se finalizo el experimento a los 10 meses. Las cosechas se efectuaron con intervalos a traves del ciclo de crecimiento, y se suplementaron con mediciones de la distribucion de las raices mas finas, la produccion foliar y la senescencia, el status del agua del suelo de la planta y la respuesta estomatal. Como resultado del estres, el cv. de desarrollo tardio M Mex 59 mejoro su rendimiento sobre los testigos a los 10 meses. Se busca una explicacion del comportamiento de los 2 cv. en cuanto a los efectos relativos de la escasez de agua sobre la produccion y distribucion de la MS, la dinamica de la parte aerea y las ralaciones internas del agua de la planta. (RA-CIAT