Lichen-induced biomodification of calcareous surfaces: Bioprotection versus biodeterioration

Studies demonstrate the active and passive capability of lichens to inhibit or retard the weathering of calcareous surfaces. Lichen coverage may actively protect a surface through shielding by the thallus and the binding and waterproofing of the rock surface and subsurface by fungal hyphae. Passive protection of rock surfaces may be induced by the formation of an insoluble encrustation, such as calcium oxalate, at the lichen-rock interface. Recent research suggests that the decay of hyphae, induced by changes in microenvironmental conditions, necrosis, parasitism or the natural physiological traits of particular lichen species, may expose a chemically and physically weakened substrate to dissolution triggering relatively rapid weathering-related surface lowering. Consequently, certain epilithic crustose and endolithic lichens may induce a period of surface stability throughout the course of their lifespan, followed by a phase of instability and rapid episodic microtopographical evolution after death and decay. A series of conceptual models is proposed to illustrate this idea over short (single lichen lifespan) and long (multiple lichen lifespans) timescales. The models suggest that the microscale biogeomorphological system of lichen-rock interaction is underpinned by nonlinear dynamical system theory as it exhibits dynamical instability and is consequently difficult to predict over a long timescale. Dominance by biodeterioration or bioprotection may be altered by changes in lichen species or in environmental conditions over time.

Mapping stone surface temperature fluctuations: Implications for lichen distribution and biomodification on historic stone surfaces

The exposure of historic stone to processes of lichen-induced surface biomodification is determined, first and foremost, by the bioreceptivity of those surfaces to lichen colonization. As an important component of surface bioreceptivity, spatiotemporal variation in stone surface temperature plays a critical role in the spatial distribution of saxicolous lichen on historic stone structures, especially within seasonally hot environments. The ornate limestone and tufa stairwell of the Monastery of Cartuja (1516), Granada, Spain, exhibits significant aspect-related differences in lichen distribution. Lichen coverage and
diurnal fluctuations in stone surface temperature on the stairwell were monitored and mapped, under anticyclonic conditions in summer and winter, using an infrared thermometer and Geographical Information Systems approach. This research suggests that it is not extreme high surface temperatures that
determine the presence or absence of lichen coverage on stonework. Instead, average stone surface temperatures
over the course of the year seem to play a critical role in determining whether or not surfaces are receptive to lichen colonization and subsequent biomodification. It is inferred that lichen, capable of surviving extreme surface temperatures during the Mediterranean summer in an ametabolic state, require a respite period of lower temperatures within which they can metabolize, grow and reproduce.
The higher the average annual temperature a surface experiences, the shorter the respite period for any lichen potentially inhabiting that surface. A critical average temperature threshold of approximately 21 ?C has been identified on the stairwell, with average stone surface temperatures greater than this
generally inhibiting lichen colonization. A brief visual condition assessment between lichen-covered and lichen-free surfaces on the limestone sections of the stairwell suggests relative bioprotection induced by lichen coverage, with stonework quality and sharpness remaining more defined beneath lichen-covered surfaces. The methodology employed in this paper may have further applications in the monitoring and mapping of thermal stress fatigue on historic building materials.

A late-Middle Pleistocene (Marine Isotope Stage 6) vegetated surface buried by Old Crow tephra at the Palisades, interior Alaska

A 40 cm thick primary bed of Old Crow tephra (131 ± 11 ka), an important stratigraphic marker in eastern Beringia, directly overlies a vegetated surface at Palisades West, on the Yukon River in central Alaska. Analyses of insect, bryophyte, and vascular plant macrofossils from the buried surface and underlying organic-rich silt suggest the local presence of an aquatic environment and mesic shrub-tundra at the time of tephra deposition. Autochthonous plant and insect macrofossils from peat directly overlying Old Crow tephra suggest similar aquatic habitats and hydric to mesic tundra environments, though pollen counts indicate a substantial herbaceous component to the regional tundra vegetation. Trace amounts of arboreal pollen in sediments associated with the tephra probably reflect reworking from older deposits, rather than the local presence of trees. The revised glass fission-track age for Old Crow tephra places its deposition closer to the time of the last interglaciation than earlier age determinations, but stratigraphy and paleoecology of sites with Old Crow tephra indicate a late Marine Isotope Stage 6 age. Regional permafrost degradation and associated thaw slumping are responsible for the close stratigraphic and paleoecological relations between Old Crow tephra and last interglacial deposits at some sites in eastern Beringia. © 2009 Elsevier Ltd.

Revue d'infanterie

1910/01/15 (A24,VOL47,N277).

Office of the University President Sous fonds: Dr. James A. Gibson

Dr. James A. Gibson was born in Ottawa on January 29, 1912 to John W. and Belle Gibson. At an early age the family moved to Victoria, B.C. where John W. Gibson was a director of the Elementary Agricultural Education Branch, Department of Education. Gibson received his early education in Victoria, receiving a B.A. (honours) at UBC in 1931. In 1931 he was awarded the Rhodes scholarship and received his B.A., M.A., B.Litt and D. Phil at New College, Oxford. This was to be the beginning of a long and dedicated relationship with the Rhodes Scholar Association. Upon his return to Canada, Dr. Gibson lectured in Economics and Government at the University of British Columbia. In 1938 he was married to Caroline Stein in Philadelphia, and the same year joined the staff of the Department of External Affairs as a Foreign Service officer. Within twenty minutes of his arrival he was seconded to the Office of the Prime Minister and Secretary of State for External Affairs, W. L. Mackenzie King in charge of War Records and Liaison Officer. This was a critical time in the history of Canada, and Dr. Gibson experienced firsthand several milestones, including the Royal Visit of King George VI and Queen Elizabeth in 1939. Dr. Gibson was present at the formation of the United Nations in San Francisco in 1945, being part of the Prime Minister’s professional staff as well as attending conferences in Washington, Quebec and London as an advisor to the Canadian delegation. Gibson contributed many articles to the publication bout de papier about his experiences during these years. After his resignation in 1947, Gibson joined the staff of the fledgling Carleton College, as a lecturer. In 1949 he was appointed a professor and in 1951 became Dean of Arts and Sciences. Dr. Gibson acted as President from 1955 to 1956 upon the sudden death of Dr. MacOdrum. In 1963 Dr. Gibson accepted the invitation of the Brock University Founders’ Committee, chaired by Arthur Schmon, to become the founding president. Dr. Gibson guided the new University from a converted refrigeration plant, to an ever expanding University campus on the brow of the Niagara Escarpment. Dr. Gibson remained firmly “attached” to Brock University. Even after official retirement, in 1974, he retained the title President Emeritus. Gibson’s final official contribution was an unpublished ten year history of the University. In retirement Gibson remained active in scholarly pursuits. He was a visiting scholar at the Center of Canadian Studies, University of Edinburgh; continued his ongoing research activities focusing on W. L. Mackenzie King, the Office of the Governor General of Canada, and political prisoners transported to Van Dieman’s Land. He remained active in the Canadian Association of Rhodes Scholars, becoming editor from 1975 to 1994 and was appointed Editor Emeritus and Director for Life in 1995 in honour of his dedicated and outstanding service. In 1993 he was awarded one of Canada’s highest achievements, the Order of Canada. Gibson retained close ties with Brock University and many of its faculty. He maintained an office in the Politics Department where he became a vital part of the department. In 1996 Brock University honoured Gibson by naming the University Library in his honour. James A. Gibson Library staff was instrumental in celebrating the 90th birthday of Gibson in 2002, with a widely attended party in the Pond Inlet where many former students, including Silver Badgers. The attendees also included former and current colleagues from Brock University, Canadian Rhodes Scholars Association, family and friends. Gibson was later to remark that the highlight of this event was the gift of his original academic robe which he had personally designed in 1964. In 2003 Dr. Gibson moved to Ottawa to be near some of his children and the city of his birth and early career. In that year “two visits to Brock ensued: the first, to attend a special celebration of the James A. Gibson Library; his late to attend the 74th Convocation on Saturday, October 18, 2003. A week later, in Ottawa, he went for a long walk, returned to his residence, Rideau Gardens, went into the lounge area, took off his coat and folded it up, put it on the back of his chair, sat down, folded his hands in his lap, closed his eyes, and died”. With sources from: Carleton University The Charlatan, Gibson CV, and Memorial Service Programme

Perspectivas del intercambio comercial entre Colombia y Francia: sector agropecuario

Colombia es un país que aún no llega al pleno desarrollo de sus relaciones comerciales más cuando de intercambios comerciales con Europa se trata. Este desarrollo se entiende como el hecho de haber trazado un largo trayecto del comercio internacional

Rabbit food.

Historia donde los niños descubren que los adultos también pueden ser caprichosos con la comida. John, un joven conejo, se niega a comer sus verduras. Frustrado, su padre pide la ayuda de Tío Bunny, que se ofrece para cuidar de sus sobrinos durante el fin de semana con la instrucción, que John coma de todo. Participando con los jóvenes en actividades físicas y deportivas el tío consigue que todos tengan hambre, entre ellos John, que sucumbe a su voraz apetito y come verduras. Sin embargo, aunque el tío explica la necesidad de comer verduras, se las arregla para evitar comer su zanahoria. Cuando se lo dice su sobrino, el tío Bunny reconoce su aversión por la raíz, aunque admite, de acuerdo, no son malas.

The Julian C. Stanley Study of Exceptional Talent : una aproximaci??n personalizada para dar respuesta a las necesidades de los estudiantes con altas capacidades

Resumen basado en el de la publicaci??n

O narrador e a presença da sátira menipéia em The adventures of Tom Sawyer

Pós-graduação em Letras - FCLAS

Mark Twain: um patriota antiimperialista e seu relato de viagem em The innocents abroad or the new pilgrim's progress

Pós-graduação em Letras - FCLAS

Romances rebeldes - a tradição de rebeldia na literatura norte-americana: de Moby Dick a On the Road

Pós-graduação em Estudos Literários - FCLAR

Panamericanismo, hispanidad, nacionalismo argentino : dos escenas

Durante los últimos años del siglo XIX y principios del XX los más importantes representantes del modernismo poético, que por entonces tenía su sede principal en Buenos Aires, toman caminos políticos divergentes. Mientras Darío, tras la guerra de Cuba, emprende una vía de reencuentro con España -que lo llevará a ser revalorizado por los escritores del Noventa y ocho español, que antes habían atacado su afrancesamiento-, Lugones irá radicalizando su giro nacionalista, hasta terminar en la fuerte afirmación de la especificidad argentina en los libros publicados entre los centenarios de la Revolución de Mayo (1910) y de la Independencia (1916). Este trabajo busca reconstruir parte del campo intelectual del periodo para seguir algunas de sus líneas de fuerza fundamentales.

Xenismos y préstamos léxicos del español de Córdoba (Argentina)

Esta ponencia se enmarca dentro de un proyecto de mayor amplitud e intenta mostrar la presencia de xenismos o extranjerismos y de préstamos léxicos en el español de Córdoba (Argentina), referidos al microcampo de transportes y viajes. La propuesta involucra una perspectiva sincrónica de finales del siglo XX y comienzos del XXI sobre el léxico no patrimonial del habla cordobesa y tiene la ambición de ser diacrónica, ya que remite a los extranjerismos, anglicismos y galicismos empleados en los albores del siglo XX (el tempus) y cristalizados en la prensa escrita de 1910. El locus de este trabajo es el habla de Córdoba. Nuestro corpus de análisis está constituido por el siguiente material lingüístico: a) selección de artículos periodísticos locales referidos al transporte de Córdoba y viajes durante 1910 y consulta de diarios cordobeses de finales del siglo XX y principios del XXI; b) grabaciones de registros coloquiales, informantes cultos de las tres generaciones, en la sincronía de los años 2000 y 2003; c) entrevistas de indagación léxica a 13 informantes de las tres generaciones, concernientes a 369 ítemes sobre el microcampo léxico mencionado. La investigación tiene como propósito: a) mostrar la riqueza léxica de los extranjerismos y préstamos en 1910 y en la sincronía actual del español de Córdoba; b) analizar la filiación idiomática de los vocablos registrados y c) señalar en la perspectiva diacrónica los procesos de evolución mediante la adopción de voces extranjeras.

Panamericanismo, hispanidad, nacionalismo argentino : Dos escenas

Durante los últimos años del siglo XIX y principios del XX los más importantes representantes del modernismo poético, que por entonces tenía su sede principal en Buenos Aires, toman caminos políticos divergentes. Mientras Darío, tras la guerra de Cuba, emprende una vía de reencuentro con España -que lo llevará a ser revalorizado por los escritores del Noventa y ocho español, que antes habían atacado su afrancesamiento-, Lugones irá radicalizando su giro nacionalista, hasta terminar en la fuerte afirmación de la especificidad argentina en los libros publicados entre los centenarios de la Revolución de Mayo (1910) y de la Independencia (1916). Este trabajo busca reconstruir parte del campo intelectual del periodo para seguir algunas de sus líneas de fuerza fundamentales