Land use in the northern Coachella Valley

Satellite imagery has proved to have great utility for monitoring land use change and as a data source for regional planning. In California, open space desert resources are under severe pressure to serve as a source for recreational gratification to individuals living in the heavily populated southern coastal plain. Concern for these sensitive arid environments has been expressed by both federal and state agencies. The northern half of the Coachella Valley has historically served as a focal point for weekend recreational activity and second homes. Since demand in this area has remained high, land use change from rural to urban residential has been occurring continuously since 1968. This area of rapid change is an ideal site to illustrate the utility of satellite imagery as a data source for planning information, and has served as the areal focus of this investigation

Evaluation of Skylab EREP data for land resource management

There are no author-identified significant results in this report

Pulse generation without gain-bandwidth limitation in a laser with self-similar evolution

With existing techniques for mode-locking, the bandwidth of ultrashort pulses from a laser is determined primarily by the spectrum of the gain medium. Lasers with self-similar evolution of the pulse in the gain medium can tolerate strong spectral breathing, which is stabilized by nonlinear attraction to the parabolic self-similar pulse. Here we show that this property can be exploited in a fiber laser to eliminate the gain-bandwidth limitation to the pulse duration. Broad (̃200 nm) spectra are generated through passive nonlinear propagation in a normal-dispersion laser, and these can be dechirped to ̃20-fs duration

Caractéristiques de l’aviculture villageoise et influence des techniques d’amélioration sur ses performances zootechniques dans la province du Sourou, région Nord-Ouest Burkinabè

Une caractérisation des systèmes d’élevage par des enquêtes combinées avec des suivis et mesures de paramètres zootechniques a été conduite dans dix huit (18) villages et un échantillon de (36) aviculteurs de la province du Sourou. Le but était aussi d’évaluer l’influence des techniques d’amélioration sur les performances zootechniques. Le système d’élevage est extensif, quelquefois semi-intensif. L’étude révèle des contraintes d’ordre sanitaire, alimentaire, d’habitat des volailles. Le suivi montre que les sujets en claustration ont une croissance plus élevée (P<0,05) à 16 semaines puisque les poids vifs ont atteint 1232 g / sujet en mode divagant et 1689 g / sujet en mode claustration. Les mortalités de 8,02% montrent une probabilité de survie numériquement meilleure en comparaison avec les sujets en divagation (18,50%). Les performances zootechniques restent relativement bonnes au regard des conditions de production des différents modes d’élevage. Une amélioration de la productivité s’impose et attention particulière sera accordée à une alimentation utilisant des ressources alimentaires locales, une conduite de l’élevage incluant un accès aux soins vétérinaires et un habitat adéquat. L’amélioration génétique des races locales par l’introduction de coqs améliorateurs est à renforcer.Mots clés : Burkina Faso, poulets, systèmes d’élevage, performances zootechniques

THE GEOLOGY AND GEOPHYSICAL STUDIES OF A GRAVEL DEPOSIT IN UNIVERSITY OF ILORIN, SOUTHWESTERN NIGERIA

Vertical electrical drilling and horizontal profiling methods of electrical resistivity have been employed to study the occurrence of gravel deposit in an area of 3.36sqkm within the University of Ilorin permanent site, Southwestern Nigeria. The petrological characteristics of the deposit were also investigated for assessing it suitability as construction aggregate materials. The gravel deposit varies from conglomeratic sandstone to sand- supported conglomerates. They are unsorted to poorly sorted and dominated by angular to sub-angular pebble clast. Results from the analysis of the geophysical data showed that the study area is underlined by three to four geoelectric layers. These layers are the top soil, the gravel layer, the weathered rock and the fresh basement rock. The top soil is 0.3m-0.9m thick but absent in elevated places due to erosion. The gravel layer is 1.8 – 7.2m with 110-490 Wm resistivity values. The weathered basement is often undifferentiated from the gravel layer, but where established, it has a thickness of 2.3-8.3m and characterized by 530-5099Wm resistivity values. The gravel layer has an average thickness of 3.1m and amounts to an estimated reserve of 20.13x102 tonnes. Depth to the fresh basement rocks is generally shallow, often less than 15m. High proportion of rough edges (angular/subangular) particles in the gravel aggregates and the abundance of quartz, feldspar and mica minerals which are not chemically reactive with Portland cement recommend the gravel as suitable for construction purposes. Also, the 1:8 ratio of the thickness of the overburden to that of the gravel qualifies the deposit to be an economically exploitable deposit

Electrostatic Turbulence and Debye-scale Structures in Collisionless Shocks

We present analysis of more than 100 large-amplitude bipolar electrostatic structures in a quasi-perpendicular supercritical Earth's bow shock crossing, measured by the Magnetospheric Multiscale spacecraft. The occurrence of the bipolar structures is shown to be tightly correlated with magnetic field gradients in the shock transition region. The bipolar structures have negative electrostatic potentials and spatial scales of a few Debye lengths. The bipolar structures propagate highly oblique to the shock normal with velocities (in the plasma rest frame) of the order of the ion-acoustic velocity. We argue that the bipolar structures are ion phase space holes produced by the two-stream instability between incoming and reflected ions. This is the first identification of the ion two-stream instability in collisionless shocks

Thermal tolerance, climatic variability and latitude

The greater latitudinal extents of occurrence of species towards higher latitudes has been attributed to the broadening of physiological tolerances with latitude as a result of increases in climatic variation. While there is some support for such patterns in climate, the physiological tolerances of species across large latitudinal gradients have seldom been assessed. Here we report findings for insects based on published upper and lower lethal temperature data. The upper thermal limits show little geographical variation. In contrast, the lower bounds of supercooling points and lower lethal temperatures do indeed decline with latitude. However, this is not the case for the upper bounds, leading to an increase in the variation in lower lethal limits with latitude. These results provide some support for the physiological tolerance assumption associated with Rapoport's rule, but highlight the need for coupled data on species tolerances and range size