A Fifteen Year Performance Summary of Fibrous PC Concrete Overlay Research in Greene County, Iowa, HR-165, 1989

The Greene County, Iowa, overlay project, completed in October 1973, was evaluated in October 1978, after five years in October 1983, after ten years and most recently in October 1988 after fifteen years of service. The 33 fibrous concrete sections, four CRCP sections, two mesh reinforced and two plain concrete sections with doweled reinforcement were rated relative to each other on a scale of 0 to 100. The rating was conducted by original members of the Project Planning Committee, Iowa DOT, Iowa County, Federal Highway Administration and industry representatives. In all, there were 23, 25 and 17 representatives who rated the project in 1978, 1983 and 1988 respectively. The 23, 25 or 17 values were then averaged to provide a final rating number for each section or variable. All experimental overlay sections had performed quite well in the period from five through 15 years, experiencing only limited additional deterioration.

Kipus: revista andina de letras. 17 (Reseñas)

Presenta las reseñas de los siguientes libros: Antonio Rodríguez Vicéns, DICCIONARIO DE EL QUIJOTE, Quito: Produbanco, 2003, 813 pp. -- Yanna Hadatty Mora, AUTOFAGIA Y NARRACIÓN: ESTRATEGIAS DE REPRESENTACIÓN EN LA NARRATIVA IBEROAMERICANA DE VANGUARDIA, 1922-1935, Madrid: Iberoamericana / Vervuert, 2003, 165 pp. -- Jorge Velasco Mackenzie, RIO DE SOMBRAS,Quito: Alfaguara, 2003, 268 pp. -- Martha Chávez, UNO DE ESTOS TRISTES DÍAS VIRTUALES, Guayaquil: Imaginaria, 2003. -- Jorge Dávila Vázquez, CÉSAR DÁVILA ANDRADE, COMBATE POÉTICO Y SUICIDIO, Cuenca: Facultad de Filosofía, Letras y Ciencias de la Educación, Universidad de Cuenca / Universidad Andina Simón Bolívar, Sede Ecuador, 1998, 348 pp. -- Yvonne Zúñiga, EL ALDABÓN DEL SUEÑO, Quito: Eskeletra Editorial, 2004, 128 pp. -- Carlos Vallejo, EN MI CUERPO NO SOY LIBRE, Quito: Edición de autor, 2003, 85 pp. -- Sandra Uribe Pérez, Sola sin tilde, Quito: Arcano Editores, 2003, 70 pp. -- Santiago Argüello Mejía, CUESTA ARRlBA, Quito: Casa de la Cultura Ecuatoriana, 2003. -- Carolina Andrade, REVISTA y REVUELTA, Quito: Eskeletra, 2003, 114 pp. -- Grínor Rojo DIEZ TESIS SOBRE LA CRÍTICA, Santiago de Chile: Lom Ediciones, 2001. -- Ricardo Maruri Castillo, PRESIDIO EN EL PARAÍSO, Guayaquil: Editorial Imaginaria, 2003, 64 pp. -- Abdón Ubidia: LA MADRIGUERA, Quito: El Conejo / Eskeletra, 2004, 346 pp.

Seasonal changes in daily metabolic patterns of tegu lizards (Tupinambis merianae) placed in the cold (17 degrees C) and dark

Oxygen consumption rate was measured continuously in young tegu lizards Tupinambis merianae exposed to 4 d at 25 degrees C followed by 7-10 d at 17 degrees C in constant dark at five different times of the year. Under these conditions, circadian rhythms in the rate of oxygen consumption persisted for anywhere from 1 d to the entire 2 wk in different individuals in all seasons except the winter. We also saw a progressive decline in standard oxygen consumption rate (at highly variable rates in different individuals) to a very low rate that was seasonally independent (ranging from 19.1 +/- 6.2 to 27.7 +/- 0.2 mL kg(-1) h(-1) across seasons). Although this degree of reduction appeared to take longer to invoke when starting from higher metabolic rates, tegu lizards reduced their metabolism to the low rates seen in winter dormancy at all times of the year when given sufficient time in the cold and dark. In the spring and summer, tegus reduced their standard metabolic rate (SMR) by 80%-90% over the experimental run, but only roughly 20%-30% of the total fall was due to the reduction in temperature; 70%-80% of the total fall occurred at constant temperature. By autumn, when the starting SMR on the first night at 25 degrees C was already reduced by 59%-81% (early and late autumn, respectively) from peak summer values, virtually all of the fall (63%-83%) in metabolism was due to the reduction in temperature. This suggests that the temperature-independent reduction of metabolism was already in place by autumn before the tegus had entered winter dormancy.

Argon ratios, 40Ar/39Ar datings and biostratigraphic ages of ODP Leg 165 sites

Drilling in the Caribbean Sea during Ocean Drilling Program Leg 165 has recovered a large number of silicic tephra layers and led to the discovery of three major episodes of explosive volcanism that occurred during the last 55 m.y. on the margins of this evolving ocean basin. The earliest episode is marked by Paleocene to early Eocene explosive volcanism on the Cayman Rise, associated with activity of the Cayman arc, an island arc that was the westward extension of the Sierra Maestra volcanic arc in southern Cuba. Caribbean sediments also document a major mid- to late Eocene explosive volcanic episode that is attributed to ignimbrite-forming eruptions on the Chortis Block in Central America to the west. This event is contemporaneous with the first phase of activity of the Sierra Madre volcanic episode in Mexico, the largest ignimbrite province on Earth. In the Caribbean sediments, a Miocene episode of explosive volcanism is comparable to the Eocene event, and also attributed to sources in the Central American arc to the west. Radiometric 40Ar/39Ar dates have been obtained for biotites and sanidines from 27 tephra layers, providing absolute ages for the volcanic episodes and further constraining the geochronology of Caribbean sediments. Volcanic activity of the Cayman arc is attributed to the northward subduction of the leading edge of the oceanic plate that carried the Caribbean oceanic plateau. Although the factors generating the large episodes of Central American explosive volcanism are unclear, we propose that they are related to contemporary major readjustments of plate tectonic configuration in the Pacific.

Plio-Pleistocene Mg/Ca and TEX86 sea surface temperature records of ODP Sites 184-1143 and 165-999,

The western warm pools of the Atlantic and Pacific oceans are a critical source of heat and moisture for the tropical climate system. Over the past five million years, global mean temperatures have cooled by 3-4 °C. Yet, current reconstructions of sea surface temperatures indicate that temperature in the warm pools has remained stable during this time. This stability has been used to suggest that tropical sea-surface temperatures are controlled by some sort of thermostat-like regulation. Here we reconstruct sea surface temperatures in the South China Sea, Caribbean Sea and western equatorial Pacific Ocean for the past five million years, using a combination of the Mg/Ca, TEXH86-and Uk'37 surface temperature proxies. Our data indicate that during the period of Pliocene warmth from about 5 to 2.6 million years ago, the western Pacific and western Atlantic warm pools were about 2 °C warmer than today. We suggest that the apparent lack of warming seen in the previous reconstructions was an artefact of low seawater Mg/Ca ratios in the Pliocene oceans. Taking this bias into account, our data indicate that tropical sea surface temperatures did change in conjunction with global mean temperatures. We therefore conclude that the temperature of the warm pools of the equatorial oceans during the Pliocene was not limited by a thermostat-like mechanism.