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La permanencia de asentamientos informales en Latinoamérica es reflejo de las insuficientes políticas públicas y de mercados incapaces de proveer oferta habitacional para grupos pobres de la sociedad, pero también es manifestación del pulso de pobladores por gestionar alternativas de vivienda. Este artículo describe los primeros impactos de la emergencia sanitaria por COVID-19 en materia habitacional, a partir del ejemplo de la consolidación del campamento Altos de Placilla Nuevo (Valparaíso, Chile). A través de una metodología mixta y participativa, se profundizó en las decisiones para el traslado al campamento, el proceso de autoconstrucción y las experiencias del habitar. Se concluye que, si bien la pandemia fue un factor acelerante que expuso la vulnerabilidad de familias de bajos recursos, habitar el campamento permitió mejorar sus condiciones de vida, tanto en un contexto de abandono como de incertidumbre.

Resumen: Tras el terremoto que afectó críticamente a la región de Atacama en 1922, se desató un intenso debate sobre la reconstrucción de Vallenar. Como consecuencia, se presentaron técnicos y serios informes que contenían las características que debía incorporar la nueva ciudad. Si bien tales propuestas no se llegaron a desarrollar, este artículo estudia tres iniciativas y los motivos que limitaron esta histórica oportunidad de transformarla. Se propone como hipótesis que tales problemáticas visibilizadas en las propuestas trascendieron a la coyuntura de 1922, en tanto existían antecedentes de desastres en las décadas anteriores que ya esbozaban iniciativas de reconstrucción y de reasentamiento.

Este artículo estudia el desarrollo de la comuna de Providencia en sus primeras tres décadas, en el marco de las atribuciones que debieron asumir las municipalidades de Chile, luego de la promulgación de la Ley de la Comuna Autónoma en 1891. El estudio inicia en 1897 con la creación de la municipalidad y culmina en 1932, con la aprobación de su primer plan de transformación, momento en que la administración local se vio respaldada por el compromiso que el gobierno central tomaba con el urbanismo. La revisión de las Actas de Sesión Municipal, principal fuente de este estudio, dan cuenta que la urbanización inicial de Providencia residió en acciones aisladas de construcción de calles, de barrios y de provisión de servicios por parte de los vecinos, las que a su vez estuvieron cruzadas por debates acerca de disposiciones más generales, tal como sucedió con la primera propuesta de un plan de transformación de la comuna, en 1911. Aunque las iniciativas no lograron concretarse hasta la tercera década del siglo XX, este trabajo propone que dichos esfuerzos constituyen un importante antecedente para la posterior incorporación del urbanismo central comandado por el Estado, enmarcado en cambios institucionales, y cristalizado en la Ley y Ordenanza General de Construcciones y Urbanización, y en el Plan de Transformación Definitivo de la comuna de 1932.

Four experiments, one in each season, were carried out during 2004 in a rural area of Córdoba, central Argentina. Two pigs (Sus scrofa L.), weighing approximately 8 kg each, were used in each of the four experiments. The animals were killed by a sharp blow to the head and immediately placed in an appropriate arthropod trap. One pig was placed in the shade and the other under direct sunlight. This research was conducted to determine the seasonal structure and dynamics of arthropods that constitute the sarcosaprophagous community in a given area of the central region of Argentina. The decomposition process was divided into five stages: fresh, bloated, decay, advanced decay and dry. The duration of each stage varied in different seasons, showing that the temperature and humidity are the most important variables that influence this process. A total of 51,500 adults and 36,909 immature were collected. More than 80% of the specimens collected belong to Insecta, and within this, Diptera were the most abundant order. The flies were mainly represented by adults and immature of the following species: Chrysomya albiceps (Wiedemann) (Calliphoridae), Musca domestica Linnaeus (Muscidae) and Fannia femoralis (Stein) (Fanniidae). Coleoptera were mainly represented by adults and immature of the species Creophilus maxillosus (Linnaeus) (Staphylinidae) and Dermestes maculatus (Geer) (Dermestidae). More than 50% of hymenopteran fauna collected belong to Formicidae. The trophic levels associated with the decomposition of the remains included five categories: necrophagous, parasites and predators of the necrophagous species, omnivores, opportunists and adventives. During faunal succession a strong dominance of the necrophagous species of the family Calliphoridae and Muscidae was observed, mainly during the early stages of decay process in all seasons.

AIM: The purpose of this work was to determine genera diversity, structural attributes and distribution of the Hydrachnidia assemblages and their possible influences with certain abiotic parameters along the sub-basin of the Grande River, a 6th order stream in the province of San Luis; METHODS: four sampling sites (C1, E1, E2 and E3) were established in two different hydrological periods: high waters (HW) and low waters (LW). Twenty-four samples were obtained using Surber sampler, and the hydraulic, physical and chemical characterization of the sampling sites was carried out. Density (ind.m-2), genus richness, Shannon-Wiener diversity index and Kownacki's dominance index were calculated; RESULTS: sixteen Hydrachnidia genera were observed. No significant differences were found between the abiotic parameters of each site. A positive correlation of Sperchon, Torrentícola and Neoatractides was observed in relation to flow and current velocity whereas Hygrobates showed a negative correlation. No significant differences were observed in Hydrachnidia abundances among the sites in HW and LW and between the pairs of each site in HW and LW. The genera with the highest densities were Hygrobates, Limnesia and Atractides, of which the first two were widely distributed. The rest only appeared sporadically. According to Kownacki's index Hygrobates and Limnesia were "dominant", Atractides were "subdominant" and the rest were "non dominant"; CONCLUSIONS: The found genera were distanced systematically and philogenetically. However, the specimens belonging to these genera exhibited very similar morphological characteristics, which were adaptations to rheophilous habitats. The representativity of Hygrobates and Limnesia might be due to the great abundance of their hosts and preys in the sub-basin. The decrease in the densities and the changes in the Hydrachnidia composition in E3 (post-dam site) might be explained by the biotic interactions previously mentioned. OBJETIVO: O objetivo deste trabalho foi conhecer a diversidade de gêneros, os atributos estruturais e a distribuição da comunidade de hidracáridos, como assim também a sua possível influência sobre certos parâmetros abióticos, na sub-bacia do Rio Grande, San Luis; MÉTODOS: estabeleceram-se quatro locais de amostragem (C1, E1, E2 e E3) em dois períodos hidrológicos: águas altas (AA) e águas baixas (AB). Obtiverem-se 24 amostras com rede Surber e se realizou a caracterização hidráulica, física e química dos locais de amostragem. Calculou-se a densidade (ind.m-2), a riqueza genérica e o índice da diversidade de Shannon-Wiener; RESULTADOS: registraram-se 16 gêneros de hidracáridos. Não houve diferenças significativas entre cada local com relação aos parâmetros abióticos. Observou-se uma correlação positiva entre Sperchon, Torrentícola e Neoatractides com relação ao fluxo e à corrente, ao passo que Hygrobates mostrou uma correlação negativa. Não houve diferenças significativas nas abundâncias absolutas de hidracáridos entre os locais em AA e AB nem entre os pares de cada local em AA e em AB. Os gêneros que apresentaram as maiores densidades foram Hygrobates, Limnesia e Atractides, dos quais os dois primeiros apresentaram-se mais amplamente distribuídos. Os demais gêneros somente apareceram esporádicamente. De acordo com o índice de Kownacki, Hygrobates e Limnesia foram "dominantes", Atractides foi "subdominante", e o resto foi "não-dominante"; CONCLUSÕES: os gêneros encontrados apresentaram-se distantes tanto filogenéticamente quanto sistemáticamente. Porém, os espécimes desses gêneros foram similares morfológicamente, apresentando características adaptativas à habitats teófilos. A representatividade de Hygrobates e Limnesia poderia se dever à grande abundância de seus hospedeiros e presas na sub-bacia. A diminuição na densidade e as mudanças na composição de hidracáridos em E3 (local após barragem) poderiam ser explicadas pelas interações abióticas antes mencionadas.

The Wnt signaling pathway plays a role in the development of the central nervous system and growing evidence indicates that Wnts also regulates the structure and function of the adult nervous system. Wnt components are key regulators of a variety of developmental processes, including embryonic patterning, cell specification, and cell polarity. In the nervous system, Wnt signaling also regulates the formation and function of neuronal circuits by controlling neuronal differentiation, axon outgrowth and guidance, dendrite development, synaptic function, and neuronal plasticity. Wnt factors can signal through three very well characterized cascades: canonical or β-catenin pathway, planar cell polarity pathway and calcium pathway that control different processes. However, divergent downstream cascades have been identified to control neuronal morphogenesis. In the nervous system, the expression of Wnt proteins is a highly controlled process. In addition, deregulation of Wnt signaling has been associated with neurodegenerative diseases. Here, we will review different aspects of neuronal and dendrite maturation, including spinogenesis and synaptogenesis. Finally, the role of Wnt pathway components on Alzheimer’s disease will be revised. Fil: Rosso, Silvana Beatriz. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Inestrosa, Nibaldo C.. Pontificia Universidad Católica de Chile; Chile

The present paper begins with the study of water mites of the Aturidae family, starting with the genus Axonopsella. Descriptions of sample area and of all Axonopsella subgenera known and their distribution are included. A new subgenus and new species, Axonopsella (Luciaxonopsella) misionum are described, and Axonopsella (Paraxonopsella) bifida Lundblad, 1937; Axonopsella (Paraxonopsella) hamata Lundblad, 1936; Axonopsella (Neoaxonopsella) hamatoides Lundblad, 1937 and Axonopsella (Neoaxonopsella) trifida Lundblad, 1937, are mentioned for the first time for Argentine. The diagnosis of the new subgenus and the new species, as well as the morphologic characteristics, measurements and geographic distributions of all species are added.

Collection of Bromus catharticus Vahl was carried out in the Argentine humid and sub-humid central area. Sixty-eight natural populations are conserved for medium and long term in Pergamino Germplasm Bank and in IRB Germplasm Bank, and ten morphological and agronomic traits were evaluated in the field during two years. There was variability for the traits considered among the accessions. Those populations from the subhumid area showed differences in valuable attributes for breeding. Exploration of marginal areas for this species might be an effective way to add variability to this collection. Coletas de Bromus catharticus Vahl foram conduzidas nas areas úmidas e sub-úmidas centrais da Argentina. Sessenta e oito populações naturais foram mantidas por médio e longo períodos nos bancos de germoplasma Pergamino e IRB, e dez características morfológicas agronômicas foram avaliadas em campo durante dois anos. Foi observada variabilidade para as características entre os acessos. As populações da região sub-úmida mostraram diferenças para características importantes para o melhoramento. A exploração de áreas marginais para esta espécie pode ser um modo efetivo de adicionar variabilidade para esta coleção de germoplasma.

When breeding temperate forage species is investigated, some attributes such as herbage accumulation and seasonal growth patterns have to be considered. To modify some of these traits, knowledge of the detailed process might be useful. In order to evaluate seasonal growth of contrasting white clover populations an experiment was carried out. Treatments were five cultivars and three local populations collected in Argentina. Weekly measures were taken during each season to calculate leaf appearance and flower appearance rates, stolon growing rate and dry matter (DM) net accumulation. Different germplasm of this species have different mechanisms for DM accumulation. Leaf size, more than leaf appearance rate, was the variable with most differences among germplasm and mostly related to dry matter accumulation. During spring and summer, inflorescences production had important effects on growing stolon rate, and differences among germplasm were evident. Some local populations showed favourable attributes that could be useful for breeding. Quando o melhoramento de forrageiras de clima temperado é investigado, alguns atributos tais como acúmulo de forragem e padrões de crescimento sazonal devem ser considerados. Para a modificação de alguns desses caracteres, o conhecimento detalhado destes processos pode ser útil. No sentido de avaliar o crescimento sazonal de populações contrastantes de trevo branco, um experimento foi conduzido. Os tratamentos consistiram de cinco cultivares e três populações nativas coletadas na Argentina. Medições semanais foram realizadas durante cada estação do ano para cálculo das taxas de aparecimento de folhas e flores, taxa de crescimento de estolões e acúmulo de matéria seca. Germoplasmas distintos para essa espécie apresentam mecanismos distintos para acúmulo de matéria seca. A característica de tamanho de folha, mais do que a taxa de aparecimento de folha, foi a variável analisada que mostrou as maiores diferenças entre os germoplasmas analisados, além de estar mais relacionada ao acúmulo de matéria seca. Durante a primavera e verão, a produção de inflorescências mostrou efeito importante na taxa de crescimento de estolões e diferenças entre os germoplasmas foram evidentes. Algumas das populações nativas apresentaram atributos favoráveis que podem ser úteis no melhoramento.

In this third paper about rheophilous water mites from Cordoba the following species and genera are mentioned for the first time for Argentina: genera Neotractides (Torrenticolidae) species Neoatractides inachus Lundblad, 1941; genera Neotyrrellia (Limnesiidae) species Neotyrrellia petricola Lundblad 1938 and genera Kongsbergia (Aturidae) species Kongsbergia (Kongsbergia) globipalpis Lundblad, 1953. Morphology of these species is described and illustrated. Biogeographical aspects of neotropical rheophilous water mites are discussed.

During 2004, four experiments were carried out, one each season, in order to determine the species composition and seasonal dynamics of Calliphoridae in a rural area of Córdoba (Argentina). Two pigs (Sus scrofa L.), weighing approximately 8 Kg each, were used in each experiment. They were killed with a blow to the head and immediately placed in a variant of the Schoenly et al. (1991) trap. One pig was exposed in the shade and the other one under direct sunlight. The insect fauna was collected daily during the four first weeks and every two or three days thereafter. A total of 16.609 adults of Calliphoridae were collected, and later on identified as one of the following seven species: Chrysomya albiceps (Wiedemann), Chrysomya megacephala (Fabricius), Phaenicia sericata (Meigen), Phaenicia eximia (Wiedemann), Cochliomyia macellaria (Fabricius), Sarconesia chlorogaster (Wiedemann) and Calliphora vicina Robineau-Desvoidy. C. albiceps was the dominant species in summer, autumn and spring, being replaced in winter by C. vicina, S. chlorogaster and P. sericata. The analysis of the seasonal distribution of the species revealed that the greater incidences are in the months of summer, autumn and spring.

Water mites from Andean part of the Bolivian Amazonian rivers were examined. A new species is described, Limnesia aymara. New records and redescription are made for Hygrobatella multiacetabulata Cook,1980, Atractides brasiliensis (Lundblad, 1937) and Krendowskia convexa (Ribaga, 1902). A new subgenus Schwoerbelobatella for hygrobatelids poliacetabulated is proposed and characterized. Ecological characteristics of the river area sampled and ecological preferences of the analyzed species are discussed. New records and redescription are made for Hygrobatella multiacetabulata Cook,1980, Atractides brasiliensis (Lundblad, 1937) and Krendowskia convexa (Ribaga, 1902). A new subgenus Schwoerbelobatella for hygrobatelids poliacetabulated is proposed and characterized. Ecological characteristics of the river area sampled and ecological preferences of the analyzed species are discussed. New records and redescription are made for Hygrobatella multiacetabulata Cook,1980, Atractides brasiliensis (Lundblad, 1937) and Krendowskia convexa (Ribaga, 1902). A new subgenus Schwoerbelobatella for hygrobatelids poliacetabulated is proposed and characterized. Ecological characteristics of the river area sampled and ecological preferences of the analyzed species are discussed. New records and redescription are made for Hygrobatella multiacetabulata Cook,1980, Atractides brasiliensis (Lundblad, 1937) and Krendowskia convexa (Ribaga, 1902). A new subgenus Schwoerbelobatella for hygrobatelids poliacetabulated is proposed and characterized. Ecological characteristics of the river area sampled and ecological preferences of the analyzed species are discussed. New records and redescription are made for Hygrobatella multiacetabulata Cook,1980, Atractides brasiliensis (Lundblad, 1937) and Krendowskia convexa (Ribaga, 1902). A new subgenus Schwoerbelobatella for hygrobatelids poliacetabulated is proposed and characterized. Ecological characteristics of the river area sampled and ecological preferences of the analyzed species are discussed. Limnesia aymara. New records and redescription are made for Hygrobatella multiacetabulata Cook,1980, Atractides brasiliensis (Lundblad, 1937) and Krendowskia convexa (Ribaga, 1902). A new subgenus Schwoerbelobatella for hygrobatelids poliacetabulated is proposed and characterized. Ecological characteristics of the river area sampled and ecological preferences of the analyzed species are discussed.Hygrobatella multiacetabulata Cook,1980, Atractides brasiliensis (Lundblad, 1937) and Krendowskia convexa (Ribaga, 1902). A new subgenus Schwoerbelobatella for hygrobatelids poliacetabulated is proposed and characterized. Ecological characteristics of the river area sampled and ecological preferences of the analyzed species are discussed. Fil: Rosso, Beatriz Elena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Diversidad Biológica y Ecológica; Argentina Fil: Fernández, Hugo R.. Fundación Miguel Lillo; Argentina Fil: Rocabado, Blanca G.. Universidad Mayor de San Andrés; Bolivia

From March 1982 to Juli 1984, an integral study on the zoobenthos was conducted on R. Mexia reservoir. Some of the species found are treated here. Family Hydryphantidae: Hydryphantes (Hydryphantes) Ju‐juyensis Nordenskiold y Neocalonyx (Paracalonyx) longipalpis Lundblad. Family Oxidae: Oxus(Oxus) patagonicus Lundblad. Family Hygrobatidae: Hygrobates (Hygrobates) ampliatus Viets. Family Mideopsis: Mideopsis (Mideopsis) choconensis Cook. Family Arrenuridae: Arrenurus (Arrenurus) oxyurus Ribaga y A. (Afegaluracarus) neuquenensis n.sp. Morphological variations and sizes of all species are given and a sound differential diagnostic for new species.

The variations in density and biomass of Hydracarina have been analyzed throughout a year in Ezequiel Ramos Mexia reservoir (Neuquen, Argentina) as a part of an integrated study on zoobenthos. Four quantitative samples were collected monthly with a Ponar grab (400 cm2) in 1 littoral and 4 sublittoral zones from June 1983 to June 1984. Some limnochemical characteristics were measured at each site. Hydracarina imagines and nymphs were identified and quantified at species level. Mean annual density and wet biomass per zone ranged from 81 to 1936 ind/m2 and from 26.0 to 201.4 mg/m2 respectively. Both parameters decreased in November remaining minimum during the summer until February. The highest values were recorded in late February and late May reaching 6006 ind/m2 and 596.3 mg/m2 respectively. Species composition and relative dominance were considerably different among zones, with Oxus patagonicus, Neocalonys longipalpis, Hygrobates ampliatus and Limnesia patagonica predominating. Parasitism of water mite l...