University of California, Santa Cruz

About: University of California, Santa Cruz is a education organization based out in Santa Cruz, California, United States. It is known for research contribution in the topics: Galaxy & Population. The organization has 15541 authors who have published 44120 publications receiving 2759983 citations. The organization is also known as: UCSC & UC, Santa Cruz.

Kepler eclipsing binary stars. ii. 2165 eclipsing binaries in the second data release

Abstract: The Kepler Mission provides nearly continuous monitoring of ~156,000 objects with unprecedented photometric precision. Coincident with the first data release, we presented a catalog of 1879 eclipsing binary systems identified within the 115 deg2 Kepler field of view (FOV). Here, we provide an updated catalog augmented with the second Kepler data release which increases the baseline nearly fourfold to 125 days. Three hundred and eighty-six new systems have been added, ephemerides and principal parameters have been recomputed. We have removed 42 previously cataloged systems that are now clearly recognized as short-period pulsating variables and another 58 blended systems where we have determined that the Kepler target object is not itself the eclipsing binary. A number of interesting objects are identified. We present several exemplary cases: four eclipsing binaries that exhibit extra (tertiary) eclipse events; and eight systems that show clear eclipse timing variations indicative of the presence of additional bodies bound in the system. We have updated the period and galactic latitude distribution diagrams. With these changes, the total number of identified eclipsing binary systems in the Kepler FOV has increased to 2165, 1.4% of the Kepler target stars. An online version of this catalog is maintained at http://keplerEBs.villanova.edu.

Effects of Natural Enemy Biodiversity on the Suppression of Arthropod Herbivores in Terrestrial Ecosystems

Abstract: Claims about the role of predator diversity in maintaining ecosystem function and providing ecosystem services such as pest control are controversial, but evaluative tests are beginning to accumulate. Empirical and experimental comparisons of species-rich versus species-poor assemblages of entomophagous arthropods and vertebrates range from strong suppression to facilitative release of herbivorous arthropod prey. Top-down control can be strengthened when natural enemies complement each other, dampened by negative interactions, balanced by both factors, and driven by single influential species. A meta-analytic synthesis shows a significant overall effect of enemy richness increasing top-down control of herbivores, which is consistent in agricultural studies conducted in tropical versus temperate zones, in studies using caged versus open-field designs, but not so in nonagricultural habitats. Synthetic analyses address theory and help set precautionary policy for conserving ecological services broadly, while characterizing uncertainty associated with herbivore response to changes in enemy diversity.

Migratory shearwaters integrate oceanic resources across the Pacific Ocean in an endless summer.

Abstract: Electronic tracking tags have revolutionized our understanding of broad-scale movements and habitat use of highly mobile marine animals, but a large gap in our knowledge still remains for a wide range of small species. Here, we report the extraordinary transequatorial postbreeding migrations of a small seabird, the sooty shearwater, obtained with miniature archival tags that log data for estimating position, dive depth, and ambient temperature. Tracks (262 ± 23 days) reveal that shearwaters fly across the entire Pacific Ocean in a figure-eight pattern while traveling 64,037 ± 9,779 km roundtrip, the longest animal migration ever recorded electronically. Each shearwater made a prolonged stopover in one of three discrete regions off Japan, Alaska, or California before returning to New Zealand through a relatively narrow corridor in the central Pacific Ocean. Transit rates as high as 910 ± 186 km·day−1 were recorded, and shearwaters accessed prey resources in both the Northern and Southern Hemisphere’s most productive waters from the surface to 68.2 m depth. Our results indicate that sooty shearwaters integrate oceanic resources throughout the Pacific Basin on a yearly scale. Sooty shearwater populations today are declining, and because they operate on a global scale, they may serve as an important indicator of climate change and ocean health.

The Low-Redshift Lyα Forest in Cold Dark Matter Cosmologies

Abstract: We study the physical origin of the low-redshift Lyα forest in hydrodynamic simulations of four cosmological models, all variants of the cold dark matter scenario. Our most important conclusions are insensitive to the cosmological model, but they depend on our assumption that the UV background declines at low redshift in concert with the declining population of quasar sources. We find that the expansion of the universe drives rapid evolution of dN/dz (the number of absorbers per unit redshift above a specified equivalent width threshold) at z1.7, but that at lower redshift the fading of the UV background counters the influence of expansion, leading to slow evolution of dN/dz. The draining of gas from low-density regions into collapsed structures has a mild but not negligible effect on the evolution of dN/dz, especially for high equivalent-width thresholds. At every redshift, weaker lines come primarily from moderate fluctuations of the diffuse, unshocked intergalactic medium (IGM) and stronger lines originate in shocked or radiatively cooled gas of higher overdensity. However, the neutral hydrogen column density associated with structures of fixed overdensity drops as the universe expands, so an absorber at z=0 is dynamically analogous to an absorber that has column density 10-50 times higher at z=2-3. In particular, the mildly overdense IGM fluctuations that dominate the Lyα forest opacity at z>2 produce optically thin lines at z<1, while the marginally saturated (NH I~1014.5 cm−2) lines at z<1 typically arise in gas that is overdense by a factor of 20-100. We find no clear distinction between lines arising in galaxy halos and lines arising in larger scale structures; however, galaxies tend to lie near the dense regions of the IGM that are responsible for strong Lyα lines. The simulations provide a unified physical picture that accounts for the most distinctive observed properties of the low-redshift Lyα forest: (1) a sharp transition in the evolution of dN/dz at z~1.7, (2) stronger evolution for absorbers of higher equivalent width, (3) a correlation of increasing Lyα equivalent width with decreasing galaxy impact parameter that extends to rp~500 h−1 kpc, and (4) a tendency for stronger lines to arise in close proximity to galaxies while weaker lines trace more diffuse large-scale structure.

The Making Of Social Movements In Latin America: Identity, Strategy, And Democracy

Abstract: * Introduction: Theory and Protest in Latin America Today Arturo Escobar and Sonia E. Alvarez. Conceptualizing Social Movements In Contemporary Latin America * Social Movements: Actors, Theories, Expectations Fernando Caldern, Alejandro Piscitelli, and Jos Luis Reyna. * Marxism, Feminism, and the Struggle for Democracy in Latin America Norma Stoltz Chinchilla. * The Study of New Social Movements in Latin America and the Question of Autonomy Judith Adler Hellman. * Culture, Economics, and Politics in Latin American Social Movements Theory and Research A. Escobar. The Making Of Collective Identities * "I Dreamed of Foxes and Hawks'': Reflections on Peasant Protest, New Social Movements, and the Rondas Campesinas of Northern Peru Orin Starn. * From Resistance to Social Movement: The Indigenous Authorities Movement in Colombia Mara Teresa Findji. * Power, Gender, and Development: Popular Women's Organizations and the Politics of Needs in Ecuador Amy Conger Lind. * The Venezuelan Ecology Movement: Symbolic Effectiveness, Social Practices, and Political Strategies Mara Pilar Garca. * Rethinking the Study of Social Movements: The Case of Christian Base Communities in Urban Brazil John Burdick. * Homosexual Identities in Transitional Brazilian Politics Edward MacRae. Articulating Strategies And Democratizing Democracy * Feminisms in Latin America: From Bogot to San Bernardo Nancy Saporta Sternbach, Marysa Navarro-Aranguren, Patricia Chuchryk, and S. E. Alvarez. * The Evolution of Urban Popular Movements in Mexico Between 1968 and 1988 Vivienne Bennett. * Radical Opposition Parties and Squatters Movements in Pinochet's Chile Cathy Schneider. * Democratization and the Decline of Urban Social Movements in Uruguay: A Political-Institutional Account Eduardo Canel. * Popular Movements in the Context of the Consolidation of Democracy in Brazil Ruth Corra Leite Cardoso. * Social Movements and Political Power in Latin America Orlando Fals Borda. * Conclusion: Theoretical and Political Horizons of Change in Contemporary Latin American Social Movements S. E. Alvarez and A. Escobar. *