Determination of Dark Matter Properties at High-Energy Colliders

If the cosmic dark matter consists of weakly-interacting massive particles, these particles should be produced in reactions at the next generation of high-energy accelerators. Measurements at these accelerators can then be used to determine the microscopic properties of the dark matter. From this, we can predict the cosmic density, the annihilation cross sections, and the cross sections relevant to direct detection. In this paper, we present studies in supersymmetry models with neutralino dark matter that give quantitative estimates of the accuracy that can be expected. We show that these are well matched to the requirements of anticipated astrophysical observations of dark matter. The capabilities of the proposed International Linear Collider (ILC) are expected to play a particularly important role in this study.Comment: 124 pages, 62 figures; corrections and new material in Section 2.6 (direct detection); misc. additional correction

The extensive age gradient of the Carina dwarf galaxy

The evolution of small systems such as dwarf spheroidal galaxies (dSph) is likely to have been a balance between external environmental effects and internal processes within their own relatively shallow potential wells. Assessing how strong such environmental interactions may have been is therefore an important element in understanding the baryonic evolution of dSphs and their derived dark matter distribution. Here we present results from a wide-area CTIO/MOSAIC II photometric survey of the Carina dSph, reaching down to about two magnitudes below the oldest main sequence turn-off (MSTO). This data-set enables us to trace the structure of Carina in detail out to very large distances from its center, and as a function of stellar age. We observe the presence of an extended structure made up primarily of ancient MSTO stars, at distances between 25arcmin-60arcmin from Carina's center, confirming results in the literature that Carina extends well beyond its nominal tidal radius. The large number statistics of our survey reveals features such as isophote twists and tails that had gone undetected in other previous shallower surveys. This is the first time that such unambiguous signs of tidal disruption have been found in a Milky Way "classical" dwarf other than Sagittarius. We also demonstrate the presence of a negative age gradient in Carina directly from its MSTOs, and trace it out to very large distances from the galaxy center. The signs of interaction with the Milky Way make it unclear whether the age gradient was already in place before Carina underwent tidal disruption.Comment: Accepted for publication in The Astrophysical Journal Letter

On the Assembly Bias of Cool Core Clusters Traced by Hα\alpha Nebulae

Do cool-core (CC) and noncool-core (NCC) clusters live in different environments? We make novel use of H$\alpha$ emission lines in the central galaxies of redMaPPer clusters as proxies to construct large (1,000's) samples of CC and NCC clusters, and measure their relative assembly bias using both clustering and weak lensing. We increase the statistical significance of the bias measurements from clustering by cross-correlating the clusters with an external galaxy redshift catalog from the Sloan Digital Sky Survey III, the LOWZ sample. Our cross-correlations can constrain assembly bias up to a statistical uncertainty of 6%. Given our H$\alpha$ criteria for CC and NCC, we find no significant differences in their clustering amplitude. Interpreting this difference as the absence of halo assembly bias, our results rule out the possibility of having different large-scale (tens of Mpc) environments as the source of diversity observed in cluster cores. Combined with recent observations of the overall mild evolution of CC and NCC properties, such as central density and CC fraction, this would suggest that either the cooling properties of the cluster core are determined early on solely by the local (<200 kpc) gas properties at formation or that local merging leads to stochastic CC relaxation and disruption in a periodic way, preserving the average population properties over time. Studying the small-scale clustering in clusters at high redshift would help shed light on the exact scenario.Comment: 17 pages, 9 figures, 2 tables, to be submitted to ApJ; comments welcom

It’s Not Easy Going Green: Obstacles to Tree-Planting Programs in East Baltimore

In 2006, government officials in Baltimore announced plans to double the city’s tree canopy over the next thirty years. While the effort has already produced positive results, many parts of the city still lack trees. In this paper we consider whether two neighborhoods in East Baltimore – Berea and Madison-Eastend – are suitable locations for tree planting. We begin by calculating how much plantable space exists in each neighborhood. We then use interview data to cast light on how residents value the urban forest and whether or not they would support efforts to increase tree canopy in East Baltimore. The selection of East Baltimore as a study area is significant because it was here that the city’s Division of Forestry encountered resistance to tree planting in the 1960s. A secondary goal of our research is to determine whether a shift in the ethnic profile of this section of the city over the past fifty years has changed the way residents perceive and value the urban forest. Our results show that while there is enough plantable space in these two neighborhoods to increase tree canopy, from approximately six percent to over 16 percent, residents are not yet ready to fully embrace an aggressive tree planting program

The Quartic Higgs Coupling at Hadron Colliders

The quartic Higgs self-coupling is the final measurement in the Higgs potential needed to fully understand electroweak symmetry breaking. None of the present or future colliders are known to be able to determine this parameter. We study the chances of measuring the quartic self-coupling at hadron colliders in general and at the VLHC in particular. We find the prospects challenging.Comment: 5 pages, 4 figure

Process-based models in Eucalyptus plantation management : reality and perspectives

Yield prediction in commercial forestry has been dominated by empirical modelling. Increasingly, however, process-based models are finding application either in support or instead of these traditional models. In this paper we draw the new forestry demands and how these models can answer different kinds of questions such as forest productivity in planted areas and new plantation, water-use, carbon sequestration and effects of climate change on forest production. In this paper we review current performance against management needs, concentrating in particular on the application of the 3-PG (Landsberg and Waring, 1997) and CABALA (Battaglia et al., 2004) process-based models. In general we find that process-based models have met many of the expectations of a decade ago. The paper briefly indicates new opportunities of process-based models in the area of wood properties and wood products prediction and in the area of forest health assessment.___________________________________La predicción de rendimientos en la silvicultura comercial ha estado dominada hasta ahora por el empleo de técnicas de modelización empíricas. Sin embargo, los modelos basados en procesos se están utilizando cada vez más como suplementos o incluso sustitutos de los tradicionales. En este artículo apuntamos nuevas demandas forestales y la forma en que los nuevos modelos pueden dar respuesta a diferentes cuestiones como la productividad forestal tanto en zonas plantadas como en nuevas plantaciones, el uso del agua, el secuestro de carbono y los efectos del cambio climático en la producción forestal. Asimismo, valoramos la eficacia de los modelos frente a las necesidades actuales de gestión, sobre todo en lo relativo a la aplicación de dos modelos basados en procesos: 3-PG (Landsberg y Waring, 1997) y CABALA (Battaglia et al., 2004). En general, los modelos de este tipo han colmado muchas de las expectativas que suscitaron hace una década. En este artículo se esbozan nuevas aplicaciones para estos modelos en cuanto a la predicción de propiedades y productos de la madera, así como a la valoración de la salud de los bosques

A new structural model for the Si(331)-(12x1) reconstruction

A new structural model for the Si(331)-(12x1) reconstruction is proposed. Based on scanning tunneling microscopy images of unprecedented resolution, low-energy electron diffraction data, and first-principles total-energy calculations, we demonstrate that the reconstructed Si(331) surface shares the same elementary building blocks as the Si(110)-(16x2) surface, establishing the pentamer as a universal building block for complex silicon surface reconstructions

Multi-source eo for dynamic wetland mapping and monitoring in the great lakes basin

Wetland managers, citizens and government leaders are observing rapid changes in coastal wetlands and associated habitats around the Great Lakes Basin due to human activity and climate variability. SAR and optical satellite sensors offer cost effective management tools that can be used to monitor wetlands over time, covering large areas like the Great Lakes and providing information to those making management and policy decisions. In this paper we describe ongoing efforts to monitor dynamic changes in wetland vegetation, surface water extent, and water level change. Included are assessments of simulated Radarsat Constellation Mission data to determine feasibility of continued monitoring into the future. Results show that integration of data from multiple sensors is most effective for monitoring coastal wetlands in the Great Lakes region. While products developed using methods described in this article provide valuable management tools, more effort is needed to reach the goal of establishing a dynamic, near-real-time, remote sensing-based monitoring program for the basin