Ultrarobust calibration of an optical lattice depth based on a phase shift

We report on a new method to calibrate the depth of an optical lattice. It consists in triggering the intrasite dipole mode of the cloud by a sudden phase shift. The corresponding oscillatory motion is directly related to the intraband frequencies on a large range of lattice depths. Remarkably, for a moderate displacement, a single frequency dominates this oscillation for the zeroth and first order interference pattern observed after a sufficiently long time-of-flight. The method is robust against atom-atom interactions and the exact value of the extra external confinement of the initial trapping potential.Comment: 7 pages, 6 figure

Modeling Soil Erosion with Emphasis on Steep Slopes and the Rilling Process

A soil erosion model, known as KYERMO, was developed for use in soil erosion research. The model was written in Microsoft FORTRAN, which is a subset of the ANSI FORTRAN 77 standard, allowing the model to be run on an IBM-PC as well as a mainframe computer. The model structure consisted of many interrelated subroutines which facilitated model development, testing, and future expansion. A sensitivity analysis of the detachment component was performed, examining the number of rills, the number of space and time steps, and the detachment parameters. This analysis indicated that the model performed as expected for the detachment limiting case. Field plots for the collection of justification data were designed and constructed on steep slopes (28 and 30.5 percent). Their surfaces were shaped to provide controlled rill patterns. Rainfall was applied through use of an irrigation nozzle rainfall simulator. The field simulations included initial full plot (22.1 m) runs on unrilled surfaces with two and six rill watersheds, full plot runs on established surfaces, and half plot runs on established surfaces. Eight field simulations were conducted. Measured or sampled quantities included runoff rate, delivered sediment concentration, delivered sediment size distribution, rainfall intensity, soil moisture content, plot surface shape, and rill cross-sections. Each of the field erosion events was simulated using KYERMO. Hydrologic parameters were fitted to provide the proper runoff characteristics to allow justification of the erosion component of the model. The detachment parameters were initially set using parameters and relationships from the literature. Prediction was comparable to that reported by other researchers. The detachment parameters were then fitted individually to gain insights about their effects. The resultant values were then considered in light of plot characteristics. These analyses indicated that a more complete knowledge of the rill bed particle size distribution could be used to increase accuracy and that soil structure changes due to tillage should be considered. The detachment rate was found to be the limiting factor rather than the sediment transport rate

Modeling Erosion on Long Steep Slopes with Emphasis on the Rilling Process

A model of soil erosion, known as KYERMO, is presented which emphasizes those processes which are important on steep slopes. Particular emphasis is placed on modeling rill development and geometry since this is the least understood process in erosion mechanics. The model requires an input rill pattern. Rainfall inputs to the model require the use of breakpoint rainfall and kinetic energy. Surface storage is calculated based on random roughness data of Linden (1979). Infiltration is modeled by use of the two layer Green-Ampt-Mein-Larson model as proposed by Moore and Eigel (1981). Runoff is related to rainfall excess and surface storage by the exponential, relationship of Thelin and Keifer (1960). Erosion is modeled separately as rill and interrill erosion. Interrill erosion is modeled by evaluating raindrop splash and interrill transport capacity. Raindrop splash is predicted by using the Bubenzer and Jones (1971) equation which requires kinetic energy, rainfall intensity, and percent clay. In terr ill transport capacity is modeled by either the Yalin (1963) or Yang (1973) equation depending on user preference. The rate of delivery of soil to a rill is a minimum of either the transport rate or splash rate. Rill detachment capacity is calculated using the shear excess equation of Foster (1982). Transport capacity is calculated from either the Yalin (1963) or Yang ( 1973) depending on user preference. The distribution of detachment around the rill boundary is calculated as a function of the shear distribution. Shear is distributed by using a modification of the area method of Lundgren and Jonsson (1964). Rill wall sloughing is calculated by using the procedure of Wu et al. (1982) which uses a critical wall angle. Flow routing in rills is calculated by using the kinematic routing procedures of Brakensiek (1966). Data is presented showing that predictions made with model components are reasonable. A limited sensitivity analysis with the model shows that predictions follow the trends that one would expect

Standing-stock Biomass and Diversity of Caulerpa (Chlorophyta) in Solong-on, Siquijor Island, Philippines

Caulerpa species growing on shallow to deep waters are considered to be both economically nuisance and important. Although invasive in the temperate regions, Caulerpa species mainly C. racemosa and C. lentillifera (lato) are harvested and consumed as food, especially in the Philippines. Caulerpa communities in Solong-on, Siquijor are one of the sources for export to neighbouring municipalities. This study aimed to determine the present standing stock biomass, percent cover and diversity of Caulerpa in Solong-on, as well as to determine the environmental parameters that may affect its abundance and diversity. The results showed a total of eight species of Caulerpa were identified in the shallow Caulerpa community in Solong-on, Siquijor. The highest standing stock biomass was obtained by C. cupressoides with mean biomass of 26.16±2.44 (SE) g dry wt m-2, whereas C. microphysa has the least standing stock biomass with an average mean of 9.16±0.26 g dry wt m-2. In general, the total standing stock biomass for all species obtained throughout the sampling period was 132.57±2.06 g dry wt m-2. Shannon-Wiener diversity index (H') ranged from 1.7-2 suggesting a relatively diverse Caulerpa community. Canonical correspondence analysis (CCA) revealed that temperature and type of substrate were the main drivers of Caulerpa biomass

Experience with the LEP vacuum system at energies above 90 GeV and future expectations

The LEP storage ring has been operated at energies above 90 GeV for more than 1000 hours during 1997. Because of the rapid increase with the beam energy of the power radiated as synchrotron light, the vacuum system has been submitted to very stringent conditions as far as power evacuation and photon stimulated gas desorption are concerned. The operational experience acquired under these, up to now unexplored, conditions will be reviewed together with an outline of the limitations which were experienced at these high levels of radiation in the use of the available vacuum instrumentation. Based o n the available data detailed predictions concerning the beam lifetime, gas desorption and beam cleaning of the vacuum system under the impact of photons with a critical energy approaching 1 MeV will be formulated

Les zones tampons humides artificielles pour réduire les pollutions des nappes par les pesticides issus des réseaux de drainage : une innovation en marche ?

Pesticides carried off by surface runoff or tile drainage system can be mitigated through “buffer zones” such as buffer strips and constructed wetlands. Buffer strips can be qualified as successful innovations since they switched from an experimental stage to their adoption in the regulatory texts and by the farmers. Constructed wetlands, still at the experimental stage in France, have required a compromise between a technical optimum and the requests of the farmers to be implemented for a first time. From an ex-post perspective for buffer strips and an ex-ante evaluation for constructed wetlands, this study analyses their transition from the concept phase to their appropriation by users. Those two devices follow each a different deployment approach but the implementation of a binding regulation, still not established for constructed wetlands, is the common denominator.Le maintien de « zones tampons » telles que les bandes enherbées permet de capter les transferts superficiels de produits phytosanitaires et les Zones Tampons Humides Artificielles (ZTHA), les transferts par les réseaux de drainage. Les premières peuvent être qualifiées d'innovations réussies dans le sens où elles sont passées d'un stade expérimental vers une adoption dans les textes réglementaires et par la profession agricole. Les deuxièmes, encore au stade expérimental, ont nécessité un compromis entre un optimum technique et les requêtes des agriculteurs, afin d'être diffusées une première fois. En nous basant sur une analyse ex-post pour les bandes enherbées et ex-ante pour les ZTHA, nous analysons leur passage depuis la phase de conception vers leur appropriation par les usagers. Le déploiement de ces deux dispositifs suit deux approches différentes mais la mise en place d'une réglementation contraignante, encore non instaurée pour les ZTHA, est le dénominateur commun