Spatial Patterns of Intraseasonal Variability of Chlorophyll and Sea Surface Temperature in the California Current

Six years of daily satellite data are used to quantify and map intraseasonal variability of chlorophyll and sea surface temperature (SST) in the California Current. We define intraseasonal variability as temporal variation remaining after removal of interannual variability and stationary seasonal cycles. Semivariograms are used to quantify the temporal structure of residual time series. Empirical orthogonal function (EOF) analyses of semivariograms calculated across the region isolate dominant scales and corresponding spatial patterns of intraseasonal variability. The mode 1 EOFs for both chlorophyll and SST semivariograms indicate a dominant timescale of similar to 60 days. Spatial amplitudes and patterns of intraseasonal variance derived from mode 1 suggest dominant forcing of intraseasonal variability through distortion of large scale chlorophyll and SST gradients by mesoscale circulation. Intraseasonal SST variance is greatest off southern Baja and along southern Oregon and northern California. Chlorophyll variance is greatest over the shelf and slope, with elevated values closely confined to the Baja shelf and extending farthest from shore off California and the Pacific Northwest. Intraseasonal contributions to total SST variability are strongest near upwelling centers off southern Oregon and northern California, where seasonal contributions are weak. Intraseasonal variability accounts for the majority of total chlorophyll variance in most inshore areas save for southern Baja, where seasonal cycles dominate. Contributions of higher EOF modes to semivariogram structure indicate the degree to which intraseasonal variability is shifted to shorter timescales in certain areas. Comparisons of satellite-derived SST semivariograms to those calculated from co-located and concurrent buoy SST time series show similar features.

Variabilidad en poblaciones de maíz nativo de la Mixteca Baja Oaxaqueña, México

La diversidad genética poblacional de maíz en México es muy dinámica y depende de factores biológicos, agroecológicos y socio-económicos, y necesidades familiares. En este trabajo se describió y clasificó la variabilidad morfológica de una colección de 60 muestras poblacionales de maíz, colectadas en 44 municipios de la Mixteca Baja Oaxaqueña (846 msnm a 1842 msnm). Las muestras se sembraron y cultivaron durante el ciclo primavera-verano de 2010, en Santo Domingo Tonala, Oaxaca, bajo un diseño de bloques completos al azar con cuatro repeticiones. Se evaluaron 19 caracteres morfológicos de planta, mazorca, grano y espiga (panoja), y se determinaron diferencias significativas entre poblacionales en estos caracteres. Los caracteres altura de planta y mazorca, días a floración masculina y femenina, y número de granos por hilera en la mazorca fueron determinantes para describir la variabilidad morfológica total. La variación morfológica y fenológica de las poblaciones de maíz se asocia con los patrones altitudinales y geográficos de donde proceden. Se determinaron seis grupos fenotípicos significativamente diferentes con características de mazorca, grano y planta semejantes a las descritas para las razas Celaya, Bolita, Pepitilla, Ancho, y ciertos complejos raciales entre Ancho, Mixteco, Celaya y Bolita.

Stable isotope record of benthic foraminifera from the Gulf of California

A high-resolution, accelerator radiocarbon dated climate record of the interval 8,000-18,000 years B.P. from Deep Sea Drilling Project site 480 (Guaymas Basin, Gulf of California) shows geochemical and lithological oscillations of oceanographic and climatic significance during deglaciation. Nonlaminated sediments are associated with cooler climatic conditions during the late glacial (up to 13,000 years B.P.), and from 10,300 to 10,800 years B.P., equivalent to the Younger Dryas event of the North Atlantic region. We propose that the changes from laminated (varved) to nonlaminated sediments resulted from increased oxygen content in Pacific intermediate waters during the glacial and the Younger Dryas episodes, and that the forcing for the latter event was global in scope. Prominent events of low delta18O are recorded in benthic foraminifera from 8,000 to 10,000 and at 12,000 years B.P.; evidence for an earlier event between 13,500 and 15,000 years B.P. is weaker. Maximum delta18O is found to have occurred 10,500, 13,500, and 15,000 years ago (and beyond). Oxygen isotopic variability most likely reflects changing temperature and salinity characteristics of Pacific waters of intermediate depth during deglaciation or environmental changes within the Gulf of California region. Several lines of evidence suggest that during deglaciation the climate of the American southwest was marked by increased precipitation that could have lowered salinity in the Gulf of California. Recent modelling studies show that cooling of the Gulf of Mexico due to glacial meltwater injection, which is believed to have occurred at least twice during deglaciation, would have resulted in increased precipitation with respect to evaporation in the American southwest during summertime. The timing of deglacial events in the Gulf of Mexico and the Gulf of California supports such an atmospheric teleconnection.

Espacios del agua en el territorio urbanizado. Los Angeles, California

Los Ángeles, en California, muestra de forma excepcional la hidrología de las grandes metrópolis en zonas de paisaje árido, basadas en grandes obras de ingeniería civil que concentran en la ciudad el agua de ámbitos geográficos muy extensos mediante aportes elevados de energía, al tiempo que canalizan la evacuación como residuo de los recursos locales. La desertización creciente derivada de este modelo sugiere la necesidad de alternativas de baja energía, basadas en la operatividad de la forma y de los sistemas vivos, para devolver al espacio y al territorio competencias de depuración, almacenaje y control de inundaciones. La construcción del suelo como infraestructura extensiva de captación, filtrado y reutilización modifica el funcionamiento hidrológico de la ciudad, reduciendo deslizamiento y escorrentía para conservar el valioso patrimonio de lluvia local y convierte la fábrica urbana en un gran sistema polivalente de gestión hidráulica. La recuperación de las cuencas locales de menor escala devuelve al agua y sus espacios su papel principal como articuladores de la forma urbana, marcando la localización de áreas húmedas y verdes. La naturaleza urbana se aleja del referente decorativo de pradera inglesa a favor de una concepción más utilitarista, entendida como una máquina orgánica integrada que resuelve la depuración, contribuye a la construcción de suelo y a la climatización a nivel metropolitano.

Migración contemporánea mexicana: redes sociales transnacionales y políticas migratorias : la experiencia migratoria de la comunidad de Tunkás, Yucatán en el sur de California

This research explores the impacts of the most recent U.S. economic crisis on the Mexican immigrant labour market, specifically from the town of Tunkás, Yucatan. Based on Bourdieu.’s theory of Capital production, and the transnational theoretical perspective, this study aims to build a conceptual frame for the migrant’s social capital in modern societies. A key element of this analysis is that a pioneer migrant-woman has initiated the tunkaseño social network in Los Angeles and Orange County, California; and has set the route to migrate to North. Finally this analysis presents how U.S. worksite enforcement policy affects the labour market that tunkaseños encounter in Southern California in the midst of a financial crisis. Tunkás, our Mayan community, native from the Southern Mexican state of Yucatan has experienced a constant migration process to California ever since the Bracero Program started. Mayan migrants have acquired new responsibilities, and a hybrid identity as transnational citizens. Yucatecan migration is defined as a contemporary Mexican migration, mostly undocumented, exacerbated during the nineties, in the midst of the Mexican financial crisis from 1994 to 1997. The present work is part of a broader research that discusses the transformation of Mexican migration patterns of different states of Mexico. This project is based on fieldwork in the communities of origin and destination. As well, on the survey results and life stories obtained during 2005-2006, and 2008-2009 by MMFRP1, where I took part in both editions as a researcher...

The Roman Catholic Church as a factor in the political and social history of Mexico.

Bibliography: p. 187-188.

Letters from Mexico

Illus. t.-p.

Rubbings from pre-columbian Mexican monuments : California Palace of the Legion of Honor, January 15, through February 28, 1955.

Mode of access: Internet.

Informe sobre la importancia de la explotacion de la cereza en California.

Mode of access: Internet.

Memorial and petition of Col. J.D. Stevenson of California.

An account of the life of Colonel Stevenson and of his services to the United States in California during the war with Mexico and the civil war.

Soil survey of Los Alamos County, New Mexico /

Issued June 1978.

The population of central Mexico in 1548; an analysis of the Suma de vistas de pueblos,

Bibliography: p. 213-215.

Investigative journalism in Mexico: between ideals and realities. The case of Morelia

The aim of this paper is to analyse the state of the investigative journalism in Mexico, especially the one that is practiced at the local level in the provinces. That is, this research is based upon a case study conducted in Morelia, the capital city of the state of Michoacán. The empirical evidence will show that there is an evident divergence regarding the practice of the investigative journalism: on the one hand, journalists are aware of what this concept involves and they consider that they practice it on a regular basis; but, on the other, the content analysis prove otherwise. In other words, the account of what is actually printed significantly differs from the news workers’ perceptions, because the former shows a poorly developed journalistic investigation practice.

La migración infantil indocumentada de Centroamérica, un desafío a la reformulación de la política migratoria de Estados Unidos. Estudio de caso de Honduras (2010-2014)

El siguiente estudio de caso analiza la influencia de la llegada de la migración infantil indocumentada centroamericana en la reformulación de la política migratoria de Estados Unidos en el período 2010-2014. Enfocándose en el caso de Honduras para dar a conocer y analizar las causas que crean las dinámicas migratorias por parte de los menores, este trabajo analiza como la llegada de estas poblaciones genera ciertos efectos en el proceso de toma de decisión de las políticas internas de los Estados Unidos. Por un lado, para resaltar las características del fenómeno migratorio, se utilizan las teorías de redes sociales y la teoría push and pull. Por otro, mediante los conceptos de Sensibilidad y Vulnerabilidad expuestos en la teoría de la Interdependencia Compleja de las Relaciones Internacionales, como también el concepto de Seguridad Societal propuesto por Barry Buzan se estudia el nivel de influencia del fenómeno infantil en el gobierno norteamericano.

Remotely sensed estimates of vegetation structural characteristics in restored wetlands, Southern California

Traditional field sampling approaches for ecological studies of restored habitat can only cover small areas in detail, con be time consuming, and are often invasive and destructive. Spatially extensive and non-invasive remotely sensed data can make field sampling more focused and efficient. The objective of this work was to investigate the feasibility and accuracy of hand-held and airborne remotely sensed data to estimate vegetation structural parameters for an indicator plant species in a restored wetland. High spatial resolution, digital, multispectral camera images were captured from an aircraft over Sweetwater Marsh (San Diego County, California) during each growing season between 1992-1996. Field data were collected concurrently, which included plant heights, proportional ground cover and canopy architecture type, and spectral radiometer measurements. Spartina foliosa (Pacific cordgrass) is the indicator species for the restoration monitoring. A conceptual model summarizing the controls on the spectral reflectance properties of Pacific cordgrass was established. Empirical models were developed relating the stem length, density, and canopy architecture of cordgrass to normalized-difference-vegetation-index values. The most promising results were obtained from empirical estimates of total ground cover using image data that had been stratified into high, middle, and low marsh zones. As part of on-going restoration monitoring activities, this model is being used to provide maps of estimated vegetation cover.