Search

Internationally, there is an under-supply of intellectual capital to provide for STEM-related employment. One contributing factor is the low number of female students selecting STEM school subjects and careers. Despite the literature recommending students engage in STEM activities earlier, many initiatives are not implemented until high school. This paper reports on an Australian project named MindSET-do which provided students with early positive STEM experiences prior to high school to raise awareness of, interest in, and aspirations for STEM-related subjects and careers. The case study surveyed n = 107 Year 6 boys’ and girls’ interests, ability beliefs and expectations in STEM school subjects and careers. Students’ awareness and interest in STEM-related subjects and careers increased significantly following experiences with inquiry-based STEM activities, χ2(1, n = 107) = 4.57 to 63.67, p < .05. Expectancy for success in mathematics was significantly higher for males than for females (U = 1125, p = .044, r = .2). Expectancy for success in science was slightly lower for the female group, but p > .05. Logistic regression found females were 24 percent less likely to have a positive view of mathematics than males (p = .003). Gender differences in STEM ability versus ability beliefs and expectancies for success are discussed, with recommendations for earlier positive experiences with STEM tasks.

Racial justice activists tend to turn to science fiction to imagine better, freer worlds. Speculative futures in design are rarely fantasy-based. Design speculation relies more on unfamiliarity and exaggeration than fantasy to challenge assumptions and norms. This paper proposes that design, futuring, and utopian thinking can offer a new path to justice movements, and a new purpose for speculative design, to envision optimistic long-term possibilities based on realism. Designers, with their unique ability to ‘change existing situations into preferred ones,’ can build realistic and plausible visions of equitable, liberatory worlds. Such visions that amplify the missions of justice efforts can help enlist new supporters and motivate advocates through complex, disruptive change. This article describes eight workshops structured to explore the value of imagining radically hopeful visions co-created through critically conscious collaborative futures. In each workshop, designers acted as facilitators to help foster solution-finding with participants from various racial justice projects in both community and academic organisations. Workshops introduced participants to the joy and strength of thinking about long-term futures. Still, their visions often did not last beyond the workshop. Only in later workshops, when design prompts provided new formats for evoking participants’ futures, did their visions become tangible and long-lasting. The results show that designers’ creative skills can complement and give shape to the deep knowledge of justice advocates.

This publication provides an in-depth profile of the air potato bulbil beetle (suggested common name), a new biological control agent of the air potato vine. It is intended for the use of interested laypersons with some knowledge of biology as well as academic audiences.

Neohydronomus affinis Hustache is known as the waterlettuce weevil (Figure 1). It is a biological control agent of the floating plant, waterlettuce, Pistia stratiotes Linnaeus (Araceae) (O’Brien & Wibmer, 1989; Center et al., 2002). Waterlettuce is found in tropical and subtropical regions of the world. It infests slow-moving streams, waterways, lakes, and rivers, forming dense floating mats that are composed of several rosettes connected by stolons (runner stems). The presence of waterlettuce mats diminishes biological diversity and generates obstructions for boating, waterflow, and aquatic organisms (Cordo & Sosa, 2000; Dray & Center, 2002). Even though waterlettuce was documented by explorer William Bartram in Florida before 1765 (plants-archive.ifas.ufl/plant-directory), it is listed as a class II prohibited aquatic plant in the State of Florida. There are three species in the genus Neohydronmus, all of which originate from South and Central America. These weevils are subaquatic, and their exoskeletons are covered in white scales with no water-resistant features. The three species are all associated with waterlettuce and feed exclusively on it (Center et al., 2002; O’Brien & Wibmer, 1989). Among them, N. affinis was first introduced as a biological control agent into Florida in 1987 at Torry Island and Kreamer Island at the south end of Lake Okeechobee (Dray et al., 1990; 2001). Since then, the insect has successfully established itself in peninsular Florida and is also reported in Louisiana (Center et al., 2002).

Este estudio tiene como finalidad la investigación sobre el desarrollo de los ingenieros en comunicaciones y electrónica (ICE) que laboran en Servicios a la Navegación en el Espacio Aéreo Mexicano (SENEAM). Con el propósito de determinar cuáles han sido las transiciones y sus proyecciones en el entorno laboral durante su permanencia en dicho organismo, y conocer y desarrollar la curva de aprendizaje desde sus inicios profesionales como ICE en el área de Ingeniería de Servicios IDS, comunicaciones, radio ayudas o radar. Las curvas de aprendizaje son modelos empíricos que permiten estudiar las transformaciones tecnológicas como resultado del aprendizaje. Partiendo de esto, el aprendizaje es comprendido como la sabiduría adquirida por la repetición de un proceso (learning-by-doing) (Arrow, 1962). Wright (1996) publicó un artículo donde afirma que la curva de aprendizaje se observó por primera vez en 1920. Al respecto, Hirschmann (1964) comenta “que la práctica hace la perfección, que las cosas se pueden hacer mejor no solo la segunda vez, sino cada vez que lo intente”; la curva de aprendizaje es la que se encarga de cuantificar y representar gráficamente este rendimiento (Hirschmann, 1964). La SENEAM cuenta con más de 40 años en México; proporcionando servicios de ayuda a la navegación aérea para la seguridad, fluidez y orden en el espacio aéreo mexicano; garantizando calidad y eficiencia conforme a la normatividad nacional e internacional aplicable. Se espera que esta investigación dé a conocer los factores que determinan la curva de aprendizaje de los ingenieros en comunicaciones y electrónica, caso SENEAM.

This publication presents management recommendations for the Brazilian peppertree. It contains information about Brazilian peppertree biology, herbicide application techniques, and the status of biological control. Written by K. T. Gioeli, S. F. Enloe, C. R. Minteer, D. M. Lieurance, and K. A. Langeland, and published by the UF/IFAS Agronomy Department, revised November 2021.

Invasive plants are non-native plant species that cause harm in their introduced range. Classical biological control of invasive plants is the use of natural enemies, imported insects and mites or pathogens, to control the target plants. This publication explains the strategies and rules in place to ensure that organisms released for the biological control of weeds are safe and effective.

Objetivos. Evaluar el riesgo entomológico de Aedes aegypti durante el recorrido fluvial en embarcaciones con rutas fronterizas de Loreto. Materiales y métodos. La población de estudio fueron los mosquitos presentes en tres embarcaciones con rutas fronterizas en Loreto. El riesgo entomológico de Aedes se determinó mediante ovitrampas, revisión de criaderos, colecta e identificación taxonómica de mosquitos adultos. Resultados. El riesgo entomológico varió según trayecto y época. Se identificó un riesgo entomológico medio a muy alto en época de creciente y en la ruta de ida hacia las zonas fronterizas. La población vectorial predominante en época de vaciante fue Mansonia sp. (74,8%), Culex sp. (12,8%) y Aedes aegypti (0,4%); en creciente predominó Culex sp. (45,1%), Mansonia sp. (26,8%) y Aedes aegypti (19,7%). En ningún caso se evidenció Aedes albopictus. Conclusiones. Existe riesgo entomológico de moderado a alto durante la etapa de creciente en las embarcaciones fluviales que viajan desde Iquitos hacia las zonas fronterizas de Loreto. Nuestros resultados evidencian que las embarcaciones fluviales son un medio de dispersión de Aedes aegypti.

Neochetina bruchi Hustache is commonly referred to as the chevroned water hyacinth weevil and is a weed biological control agent used to manage water hyacinth, Pontederia crassipes Mart. [formely Eichhornia crassipes (Mart.) Solms (Pellegrini et al. 2018)], in more than 30 countries (Winston et al. 2014). Imported from Argentina, the insect was first introduced into the United States in Florida in 1974 and released in Louisiana later in 1974 (Manning 1979), Texas 1980, and California 1982 to 1983 (Winston et al. 2014). Now Neochetina bruchi occurs throughout the Gulf Coast States (Winston et al. 2014). The target weed of Neochetina bruchi, water hyacinth, is an invasive aquatic plant in the United States and is included on Florida’s list of prohibited aquatic plants. Neochetina bruchi is among four species of insect biological control agents that have been introduced into the United States to manage water hyacinth. The other three species include a weevil, Neochetina eichhorniae; a moth, Niphograptaalbiguttalis; and a planthopper, Megamelus scutellaris, which were introduced into the United States in 1972, 1977, and 2010, respectively (Tipping et al. 2014). Although the larvae and pupae of Neochetina bruchi and Neochetina eichhorniae have similar appearance and behavior and can be difficult to differentiate by casual observation (Deloach and Cordo 1976), the adult stages of the two species of water hyacinth weevils can be distinguished relatively easily based on the color patterns on their elytra (hardened fore wings).

The 1991 explosive eruption of Hudson volcano in Chile ejected about 2.7 km3 (DRE) of basalt and trachyandesite magma as tephra fall. A majority of the fallout occurred from an eruption during the period August 12-15, 1991, producing an extensive deposit to the east of the volcano in Chile and Argentina. Dacitic, glassy tephra from this phase of the eruption exhibit a remarkable variety in particle morphology and color, ranging from dark, poorly-vesicular shards to light-colored, pipe-vesicular micropumice. Fractal analysis of glassy particle outlines shows that at least four distinct types can be discriminated: blocky, poorly-vesicular, highly vesicular with spherical vesicles, and pipe vesicular. A quantitative comparison of particle morphologies using principal component analysis of fractal spectrums of the Hudson tephra with other tephra produced by eruptions with known fragmentation mechanisms, together with SEM imaging of particle surfaces, indicates that production of the Hudson tephra involved both interaction with external water and exsolution of dissolved volatiles. Blocky particles likely represent magma that was fragmented by magma-water interactions before exsolution of all dissolved volatiles could occur. The great diversity of particle types in the August 12-15, 1991 Hudson tephra fall can be attributed to eruption of volatile-rich trachyandesite magma through an ice-filled caldera where subglacial melting led to a supply of external water that interacted intermittently with the discharge of magma driven primarily by volatile exsolution.

Includes: Introduction - Synonymy - Distribution - Description - Life Cycle - Hosts - Importance - Selected References This publication is also available on the Featured Creatures website at http://entnemdept.ufl.edu/Creatures/BENEFICIAL/alligatorweed_stem_borer.htm

Sometimes referred to as the ‘mottled water hyacinth weevil’, Neochetina eichhorniae Warner is a weevil that attacks the invasive, aquatic plant, water hyacinth, Eichhornia crassipes (Mart.) Solms. Water hyacinth is considered one of the most destructive plants in aquatic ecosystems in the United States and, as a result, is listed in both the federal noxious weed list and Florida’s list of prohibited aquatic plants. Neochetina eichhorniae is host specific and causes substantial damage to water hyacinth, making it a valuable biological control agent for this invasive weed in many parts of the world. The insect was first introduced into the United States from Argentina in 1972, when scientists released the insect in Broward County, Florida, to manage water hyacinth (Perkins 1973). Since then, the insect has been introduced in more than three dozen countries worldwide (Winston et al. 2014). Post-introduction studies indicate the insect substantially suppresses the growth of water hyacinth, significantly reducing biomass, flowers production, and water surface coverage (Grodowitz et al. 1991, Center et al. 1999, Tipping et al. 2014, Nesslage et al. 2016) and the need for herbicide applications (Haag 1986).

Review of Richard Berquist, _From Human Dignity to Natural Law_

Originally published on the Featured Creatures website at http://entnemdept.ufl.edu/creatures/beneficial/bugs/Megamelus_scutellaris.htm Includes: Introduction - Distribution - Description - Life Cycle and Biology - Hosts - Selected References

Este trabajo es un comentario del artículo: Steffens D, Maher CG, Pereira LSM, et al. Prevention of Low Back Pain: A Systematic Review and Meta-analysis. JAMA Intern Med. 2016;176(2):199–208. doi:10.1001/jamainternmed.2015.7431.

The Brazilian peppertree thrips, Pseudophilothrips ichini (Hood) (Thysanoptera: Phlaeothripidae), is an insect native to Brazil (Figure 1). This species has been studied for the last 20+ years as a potential biological control agent of Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae), in Florida (Cuda et al. 2008; Cuda et al. 2008; Manrique at al. 2014; Wheeler et al. 2016a, b). Host specificity experiments demonstrated that Pseudophilothrips ichini has a limited host range (Cuda et al. 2008; Cuda et al. 2009; Wheeler et al. 2017) and can cause a severe reduction of Brazilian peppertree biomass (Manrique at al. 2014). https://edis.ifas.ufl.edu/in1270

Objetivo: Describir las características clínicas y demográficas de los sujetos con lesión medular espinal (LME) que se rehabilitaron en el Instituto Nacional de Rehabilitación Psicofísica del Sur (I.Na.Re.P.S.) e identificar si las mismas se encuentran asociadas a las lesiones traumáticas. Materiales y método: Estudio observacional, analítico, transversal, retrospectivo que incluyó sujetos con LME que ingresaron al I.Na.Re.P.S. entre enero de 2015 y agosto de 2018. Se realizó un análisis de regresión logística múltiple para identificar características asociadas al motivo de LME (traumática versus no traumática). Como medida de asociación se reportaron los Odds Ratios (ORs) con sus respectivos intervalos de confianza al 95% (IC 95%). Se consideró significativo un valor de p4 meses [OR 4,8 (IC 95% 1,3 - 17,2); p=0,015)] y lesión completa [OR 18,0 (IC 95% 3,5 - 93,9); p=0,015)] resultaron características independientes relacionadas con lesión medular traumática. Conclusiones: La LME afectó principalmente a hombres jóvenes, producto de lesiones traumáticas, causadas por accidentes de tránsito. La edad, el tiempo de tratamiento y la lesión de tipo completa fueron características independientes relacionadas con lesión medular traumática.

Conspiracy theories are central to political discourse in Venezuela and are widely supported. In the Americas Barometer Venezuela survey from 2016 to 2017, 54 percent of respondents expressed agreement for at least one of three political conspiracy narratives unsupported by evidence. Political loyalties to Chavismo or to the anti-Chavista opposition drive much conspiracy theory belief, but not all. Politically motivated reasoning pushes some citizens toward a given conspiracy narrative but others away. Other factors that are distinct from political loyalties, including low education levels, predispositions toward Manichaeanism and fatalism, and belief in the supernatural are associated with conspiracism. This article presents new data on conspiracy theory beliefs in Venezuela as well as analysis of its individual-level correlates, then discusses how the current Venezuelan political environment fosters conspiracy and what changes might mitigate this phenomenon. Resumen Las teorías de conspiración son fundamentales para el discurso político en Venezuela y son ampliamente apoyadas. En la encuesta de Venezuela del Barómetro de las Américas de 2016 a 2017, el 54 por ciento de los encuestados expresó su acuerdo con al menos una de las tres narrativas presentadas de conspiración política que no estaban respaldadas por evidencia. Las lealtades políticas al chavismo o a la oposición anti-chavista impulsan muchas creencias de las teorías de la conspiración, pero no todas. El razonamiento motivado políticamente empuja a algunos ciudadanos a una narrativa de conspiración dada, pero a otros a alejarse. Otros factores que son distintos de las lealtades políticas, como los bajos niveles de educación, las predisposiciones hacia el maniqueísmo y el fatalismo, y la creencia en lo sobrenatural están asociados con el conspiracismo. Este artículo presenta datos sobre las creencias de la teoría de la conspiración en Venezuela, así como el análisis de sus correlatos a nivel individual, luego analiza cómo el entorno político venezolano fomenta la conspiración y qué cambios podrían mitigar este fenómeno.

Brazilian peppertree is a nonnative invasive tree widely distributed in central and southern Florida. This fact sheet provides readers with the Brazilian peppertree history in Florida, habitats where found, identification, biology and control recommendations. The control recommendations in this fact sheet include traditional herbicide strategies as well as innovative new applications of biological control.

In the late 1970s, Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae), was targeted for classical biological control in Florida because its invasive properties (see Host Plants) are consistent with escape from natural enemies (Williams 1954), and there are no native Schinus spp. in North America. The lack of native close relatives should minimize the risk of damage to non-target plants from introduced biological control agents (Pemberton 2000). [...]

In the past year, over 100 university campuses in the United States and elsewhere have witnessed student protest, specifically against institutionalized racism and in response to symptoms of the university’s neoliberal, capitalist and imperial culture. This article outlines the emergence and confluence of the corporate and imperial university, producing and reproducing the violence of consumer culture, academic containment, and institutional control. This case study of a small, elite, liberal arts college in the United States will unravel the messiness of the contact zone where university administration and student protest meet, and its meanings for those of us who find ourselves ever-contained within spaces of higher education. Through critical discourse analysis and participant observation, I provide some preliminary mapping of how the university sanitizes—how it keeps itself ‘clean’—and the different ways this is interpreted, confirmed, and resisted by its campus community. Queer and feminist readings of pollution, dirt, and bacteria contextualize the university’s response to student activism, and daily operation, in the politics of containment and cleanliness.

La Norpatagonia andina a comienzos del siglo pasado se constituyó en un espacio con relaciones desiguales de poder y una población heterogénea. Las mujeres que la habitaban se distinguían por sus orígenes de etnia y clase, las había indígenas, chilenas e inmigrantes europeas. Las aunaba sí su condición de subordinación a los mandatos masculinos. En este espacio regional pretendo analizar el rol ocupado por las mujeres inmigrantes en la primera mitad del siglo XX, que compartieron una realidad peculiar, desarrollaron su vida y sus múltiples actividades para su hogar y su familia, que constituyen un colectivo tantas veces olvidado por la historiografía. La intención de este trabajo es, desde el enfoque regional y la perspectiva de género, historiar a las mujeres, concebidas como sujetos activos de los procesos migratorios y como figuras clave para la reproducción biológica y cultural de la sociedad.Early last century, the Andean Northern Patagonia people established itself within a context of unequal power relations and a heterogeneous population. Women were then distinguished only by their ethnic and class origins, which included indigenous, Chilean and European immigrants. They were unified by their subordination to male mandates. Within this regional environment I tried to examine the role played by the immigrant women in the first half of the twentieth century; who live their life trough multiple activities in their home and for their family. Women who were usually a forgotten issue for historians. The aim of this paper is to contribute, from a regional and gender perspective, to the history studies of these women. Women who were active participants in the migration process, and had an important role in biological and cultural society reproduction.

Review of J. Bert Lott, Death and Dynasty in Early Imperial Rome (Cambridge: Cambridge University Press, 2010).

Evidence of oxidative stress in horses has been described in reports dealing with intense and endurance exercise. Oxidative stress occurs when antioxidant systems are insufficient causing oxidation to potentially damage DNA, proteins, and lipids, and contribute to degenerative changes. Vitamin E is the most commonly supplemented antioxidant in horses and has been shown that horses in exercise conditioning may require higher intakes of vitamin E than recommended. Also in various species vitamin C potentiates the effects of vitamin E; however, under maintenance conditions horses have the ability to synthesize sufficient ascorbate, the demand increases as stress on the body is increased. Competitive endurance horses were estimated to consume 1.2 to 5-times higher levels of vitamin E than recommended intakes. In these horses a negative correlation was found between the vitamin E intake and creatine kinase, and aspartate aminotransferase. Similarly, three-day event horses have vitamin E average intakes about 50% over recommended levels, and it was also found that intake of vitamin E negatively correlated with inflammatory markers. However, large doses of vitamin E at about 10-times the recommended levels could potentially interfere with beta-carotene absorption. While some studies have shown benefits of lipoic acid supplementation in endurance trained horses similar to that of vitamin E, other studies failed to show any benefit of supplemental superoxide dismutase in intensely exercising horses. The implications from this broad scope of work show potential benefits for supplementing various antioxidants however, before assuming efficacy from other species horse specific studies should be performed.Evidência de estresse oxidativo em eqüinos tem sido descrita em artigos que lidam com exercícios intensos e de resistência. O estresse oxidativo ocorre quando sistemas antioxidantes são insuficientes, causando oxidação com potencial de danificar DNA, proteínas e lipídios, e contribui para mudanças degenerativas. A vitamina E é o antioxidante mais comumente suplementado em cavalos e tem sido demonstrado que cavalos em exercício condicionado podem exigir maior consumo dessa vitamina que o recomendado. A vitamina C também potencializa o efeito da vitamina E em várias espécies. No entanto, sob condições de mantença, os cavalos têm capacidade de sintetizar ácido ascórbico suficiente, a demanda aumenta enquanto o estresse sobre o corpo aumenta. Foi estimado para cavalos de competição (corrida) um consumo de 1,2 até 5 vezes os níveis de vitamina E recomendados para ingestão. Há correlação negativa entre a ingestão de vitamina E, creatinina quinase e aspartato aminotransferase nesses cavalos. Do mesmo modo, cavalos participantes de competições de três dias ingerem em média 50% a mais dos níveis recomendados de vitamina E. Apurou-se, também, que a ingestão de vitamina E é negativamente correlacionada com marcadores inflamatórios. No entanto, grandes doses de vitamina E, cerca de 10 vezes o recomendado, poderiam interferir na absorção de beta-caroteno. Embora alguns estudos têm mostrado que os benefícios da suplementação de ácido lipóico na resistência de cavalos treinados são semelhantes aos da vitamina E, outros estudos não mostraram nenhum benefício da suplementação com superóxido desmutase, em exercícios intensos de cavalos. As implicações deste vasto campo de trabalho mostram os benéficos potenciais para suplementação de vários antioxidantes, no entanto, antes de se comprovar a eficácia, devem ser realizados estudos específicos em outras espécies de cavalos.

Glamorous and stylish, perfume is an evocative product that provokes a stimulus of the senses. The use of perfume is recognised as a significant part of daily grooming for many women. It is suggested that the basis for consumer choice for this product should be based on olfactory preference, however the process related decision-making has been shown to be more complex. The mature consumer purchase decision making in this product category is often associated with long standing, established, luxury fragrance brands. In addition, at the frontline of the perfume sales process are fragrance consultants. With direct contact to the consumer, these ‘brand ambassadors’ possess invaluable information on consumer involvement with perfume products and brands. Hence, this paper investigates CBR (consumer brand relationship) and the subsequent perfume purchase behaviour of mature female consumers (age +44) from a dual (industry and consumer) perspective. Results indicate that important perceptual differences related to brand relationships with perfume exist between fragrance consultants and experts on one hand and consumers on the other. This research promotes a deeper understanding of current consumer approach and issues surrounding female mature purchasing behaviour for this unique category of product, and, complements the growing body of literature related to luxury brands.

Objetivos. Explorar la asociación entre las variables climáticas con la transmisión de malaria en Loreto, en un periodo de 13 años. Materiales y métodos. Estudio ecológico realizado con los datos mensuales promedio de temperatura (ºC), humedad relativa (%), pluviosidad (mm) y nivel de río Amazonas (metros) con los casos de malaria confirmados por gota gruesa registrados por la Dirección Regional de Salud Loreto, se usó modelos de regresión lineal simple y múltiple. Resultados. Encontramos correlación negativa significativa entre temperatura y casos de malaria para cinco años: 1997, 1999, 2003, 2005 y 2006; nivel de río para cuatro: 1997, 1998, 2003 y 2005 y humedad para tres años: 1996, 2005, 2006. No se encontró asociación para ningún año con pluviosidad. Los modelos de regresión múltiple fueron significativos en tres años (1999, 2003 y 2006) con valores de r2 entre 0,870 y 0,937. Conclusiones. Algunas variables climáticas pueden estar asociadas con la transmisión de malaria pero la importancia de cada una de ellas puede variar año a año. Los años de presentación de El Niño o posteriores, son los años de mayor correlación. Cuando la temperatura promedio es menor es probable que los ciclos esporogónicos y gonotróficos del vector se vean favorecidos, es en ese momento que el potencial de transmisión de la población vectorial se hace máxima, lo cual favorece la transmisión de malaria.

The 1991 explosive eruption of Hudson volcano in Chile ejected about 2.7 km³ (DRE) of basalt and trachyandesite magma as tephra fall. A majority of the fallout occurred from an eruption during the period August 12-15, 1991, producing an extensive deposit to the east of the volcano in Chile and Argentina. Dacitic, glassy tephra from this phase of the eruption exhibit a remarkable variety in particle morphology and color, ranging from dark, poorly-vesicular shards to light-colored, pipe-vesicular micropumice. Fractal analysis of glassy particle outlines shows that at least four distinct types can be discriminated: blocky, poorly-vesicular, highly vesicular with spherical vesicles, and pipe vesicular. A quantitative comparison of particle morphologies using principal component analysis of fractal spectrums of the Hudson tephra with other tephra produced by eruptions with known fragmentation mechanisms, together with SEM imaging of particle surfaces, indicates that production of the Hudson tephra involved both interaction with external water and exsolution of dissolved volatiles. Blocky particles likely represent magma that was fragmented by magma-water interactions before exsolution of all dissolved volatiles could occur. The great diversity of particle types in the August 12-15, 1991 Hudson tephra fall can be attributed to eruption of volatile-rich trachyandesite magma through an ice-filled caldera where subglacial melting led to a supply of external water that interacted intermittently with the discharge of magma driven primarily by volatile exsolution.La erupción explosiva de 1991 del Volcán Hudson en Chile expulsó cerca de 2,7 km³ (DRE) de magma traquiandesítico y basáltico en forma de caída de tefra. La mayoría de la caída se produjo durante el período del 12 al 15 de agosto de 1991, a partir de una erupción que produjo un extenso depósito hacia el este del volcán, en Chile y en Argentina. Para esta fase de la erupción, la fracción vítrea correspondiente a la tefra traquiandesítica muestra composición dacítica, con fragmentos de forma y color muy variados, que fluctúan desde trizas oscuras y poco vesiculadas hasta fragmentos pumíceos de color claro e intensa vesiculación de canalículos. El análisis fractal del contorno de las partículas vítreas permite la separación en por lo menos cuatro tipos distintos: blocosas, poco vesiculadas, altamente vesiculadas con vesículas esféricas y canalículo-vesiculadas. El análisis cuantitativo de las formas de las partículas, mediante el análisis de componentes principales de los espectros fractales de las partículas de la tefra del Hudson, y su comparación con los de otras tefras producidas por erupciones cuyos mecanismos de fragmentación son conocidos, junto con las imágenes de microscopio electrónico de barrido de la superficies de las partículas, indica que la producción de tefra del Hudson es resultado de un proceso mixto que comprende la interacción del magma con agua externa y la exsolución de los volátiles disueltos en el magma. Las partículas blocosas probablemente representan magma fragmentado por interacción con agua antes de que tuviera lugar la exsolución de todos los volátiles disueltos. La gran variedad de partículas en la caída de cenizas de la erupción del 12 al 15 de agosto de 1991 del volcán Hudson puede atribuirse a la erupción de un magma traquiandesítico rico en volátiles a través de una caldera rellena de hielo, en la cual la fusión de la base del relleno de hielo aportó agua externa al sistema magmático, que interactuó intermitentemente con la descarga de magma impulsada por la exsolución de volátiles.

Research on political institutions suggests that sub-national factors affect the proclivity of legislators from the same party or coalition to vote together. We estimate the effects of such forces operating at the State-level - intra-list electoral competition, and alliance with governors. We propose that larger cohorts, in which the imperative for legislators to distinguish themselves from the group is stronger, should be less unified than smaller cohorts. We also derive from theoretical hypotheses that cohorts allied with governors may be either more or less unified than other cohorts. We analyze unity among coalition cohorts on recorded floor votes in the Brazilian Chamber of Deputies. We find support for the hypothesis that larger cohorts are less unified, but detect no net effect of alliance with governors on cohort voting unity. Governors are not dominant brokers of legislative coalitions, suggesting that the net gubernatorial effect is contingent on factors that shape their influence relative to national-level legislative actors.

This paper presents the results of a research aimed to quantify suspended sediment transport in three experimental catchments in southern Chile, to compare measured suspended sediment load with estimated erosion using the Universal Soil Loss Equation (USLE) applied in a GIS environment and to validate de Modified Universal Soil Loss Equation (MUSLE) used to estimate suspended sediment loads from forest catchments. The catchments are Los Pinos (94.2 ha), Los Ulmos 1 (12.6 ha) and Los Ulmos 2 (17.7 ha). Soil losses estimated with USLE for the three catchments are higher than those measured in runoff experimental lots under bare soil conditions, which could indicate an overestimation of the LS calculated in GIS and the fact that the USLE model does not compute sediment deposit and storage within the catchment. A statistical significant relation was found between measured and estimated (MUSLE) suspended sediment load, which would indicate that this model could be applied to estimate suspended sediment load from small catchments in southern Chile.