A Study of Fauna and Flora of the Two Communities in a Sandhill Area near Lamar, Colorado

A pilot study was conducted near Lamar in the sandhills in southeastern Colorado during the summer of 1958. The purpose of the investigation was to determine the species of plants and animals present in the area and the relative abundance of each species. Two major plant communities are common in the sandhills. They are the yucca (Yucca glauca) community and the sand sage (Artemisia filifolia). Line transects were used to determine the percentage composition and basal cover. The forbs were rated as to their relative abundance. They were rated as very abundant, abundant, frequent, common, and rare in each community. The time of flowering and seed set were recorded. The major grasses in the yucca community were blue grama (Bouteloua gracilis), buffalo grass (Buchloe dactyloides) and sand dropseed (Sporo-bolus cryptandrus). Sand dropseed was the most common grass in the sand sage area while blue grama was most abundant in the yucca community. Insects were collected and rated as to the importance of each species in the two communities. The number of grasshopper present during the study was recorded by the use of square yard quadrats. Birds were not very common in the study areas. Only ten species were considered as important. The rabbits were very abundant in the areas at the beginning of the season but the black-tailed jackrabbit (Lepus californicus) decreased in numbers during the entire summer while little change was noted in the cottontail (Sylvilagus audubonii) numbers. The coyote (Canis latrans) was perhaps the most important large mammal in the area. A large increase in the population occurred during the summer. Seven species of rodents were trapped on tile areas during the summer. Ord’s kangaroo rat (Dipodomys ordii) was the most abundant in both communities. The sandhills have been badly misused throughout the entire area of southeastern Colorado. Improved management is needed to replace tile present vegetation of sand sage, yucca, and sand dropseed with better species of grasses

Invest to Save: Report and Recommendations of the NSF-DELOS Working Group on Digital Archiving and Preservation

Digital archiving and preservation are important areas for research and development, but there is no agreed upon set of priorities or coherent plan for research in this area. Research projects in this area tend to be small and driven by particular institutional problems or concerns. As a consequence, proposed solutions from experimental projects and prototypes tend not to scale to millions of digital objects, nor do the results from disparate projects readily build on each other. It is also unclear whether it is worthwhile to seek general solutions or whether different strategies are needed for different types of digital objects and collections. The lack of coordination in both research and development means that there are some areas where researchers are reinventing the wheel while other areas are neglected. Digital archiving and preservation is an area that will benefit from an exercise in analysis, priority setting, and planning for future research. The WG aims to survey current research activities, identify gaps, and develop a white paper proposing future research directions in the area of digital preservation. Some of the potential areas for research include repository architectures and inter-operability among digital archives; automated tools for capture, ingest, and normalization of digital objects; and harmonization of preservation formats and metadata. There can also be opportunities for development of commercial products in the areas of mass storage systems, repositories and repository management systems, and data management software and tools.

Introduction: diverging or converging dynamics? EU and US policies in North Africa - an introduction

According to a number of scholars of international relations, the transatlantic relationship is going through a very significant and possibly irreversible crisis. It is claimed that the different reactions of the United States and the European Union to both September 11th and the war in Iraq were the catalyst for a rift that had been deepening for some time, leading to competition between the two actors. The literature on the foreign policy of the US and the EU in the Middle East and North Africa also points to this rift in order to explain the seemingly contradictory policies that the two actors implement in the region, with the US being more forceful in its attempts to export democracy and in supporting Israel while the EU adopts a less confrontational attitude and is perceived to be more friendly to the Palestinians. This article, which introduces a special issue on the nature of US and EU foreign policies in North Africa, argues on the contrary that the transatlantic rift does not really exist. While there are certainly differences in discourse and policies, both the EU and the US share the same concerns and have similar strategic objectives in the region, leading the two actors towards cooperation and division of labour rather than confrontation

Quantum-well states in ultrathin Ag(111) films deposited onto H-passivated Si(111)-(1x1) surfaces

Ag(111) films were deposited at room temperature onto H-passivated Si(111)-(1x1) substrates, and subsequently annealed at 300 C. An abrupt non-reactive Ag/Si interface is formed, and very uniform non-strained Ag(111) films of 6-12 monolayers have been grown. Angle resolved photoemission spectroscopy has been used to study the valence band electronic properties of these films. Well-defined Ag sp quantum-well states (QWS) have been observed at discrete energies between 0.5-2eV below the Fermi level, and their dispersions have been measured along the GammaK, GammaMM'and GammaL symmetry directions. QWS show a parabolic bidimensional dispersion, with in-plane effective mass of 0.38-0.50mo, along the GammaK and GammaMM' directions, whereas no dispersion has been found along the GammaL direction, indicating the low-dimensional electronic character of these states. The binding energy dependence of the QWS as a function of Ag film thickness has been analyzed in the framework of the phase accumulation model. According to this model, a reflectivity of 70% has been estimated for the Ag-sp states at the Ag/H/Si(111)-(1x1) interface.Comment: 6 pages, 6 figures, submitted to Phys. Rev.

Two-domains bulklike Fermi surface of Ag films deposited onto Si(111)-(7x7)

Thick metallic silver films have been deposited onto Si(111)-(7x7) substrates at room temperature. Their electronic properties have been studied by using angle resolved photoelectron spectroscopy (ARPES). In addition to the electronic band dispersion along the high-symmetry directions, the Fermi surface topology of the grown films has been investigated. Using ARPES, the spectral weight distribution at the Fermi level throughout large portions of the reciprocal space has been determined at particular perpendicular electron-momentum values. Systematically, the contours of the Fermi surface of these films reflected a sixfold symmetry instead of the threefold symmetry of Ag single crystal. This loss of symmetry has been attributed to the fact that these films appear to be composed by two sets of domains rotated 60$^o$ from each other. Extra, photoemission features at the Fermi level were also detected, which have been attributed to the presence of surface states and \textit{sp}-quantum states. The dimensionality of the Fermi surface of these films has been analyzed studying the dependence of the Fermi surface contours with the incident photon energy. The behavior of these contours measured at particular points along the Ag $\Gamma$L high-symmetry direction puts forward the three-dimensional character of the electronic structure of the films investigated.Comment: 10 pages, 12 figures, submitted to Physical Review