1,431 research outputs found

    Relevamiento de las condiciones del trabajo docente en la escuela secundaria. Un estudio de casos en el Partido de General Pueyrredon, provincia de Buenos Aires, Argentina / Survey of the conditions of teaching work in secondary school. A case study in the General Pueyrredon District, Province of Buenos Aires, Argentina

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    El objetivo de este trabajo es indagar enla percepción de directivos y docentesacerca de las condiciones de trabajo y suimpacto sobre las prácticas pedagógicas.Comenzamos describiendo el contextode la reforma educativa en los ‘90 y locomparamos con la situación actual paracomprender los profundos cambios quehan tenido lugar.Se analizan los resultados de entrevistasrealizadas a los directores y docentesde escuelas de nivel medio de GeneralPueyrredon durante el año escolar2012. Las mismas fueron tomadaspor los estudiantes de la asignatura“Sistema Educativo y Curriculum”correspondientes al Ciclo Pedagógicode la Facultad de Humanidades dela UNMdP. La actividad tuvo comopropósito familiarizar a los estudiantescon la metodología de investigación yacercarlos, en tanto futuros profesores,a los problemas presentes hoy en la educación secundaria.Por ello se decidió abordar las condicionesde trabajo en que los docentes efectivizansus prácticas tanto en la gestión públicacomo privada. Se respetó el peso ylas características de cada uno delos sectores con el fin de identificarsimilitudes y diferencias en el trabajo ylas condiciones institucionales.Las dimensiones estudiadas fueron:características del establecimiento,infraestructura; recursos humanos yrelaciones laborales. En cuanto a lascarreras de los directores fue investigadosobre la base de títulos, antigüedaddocente y en el cargo y formacióncontinua. Se abordó la percepción quetienen tanto directivos como profesoressobre la movilidad ocupacional de laprofesión, y el peso de los cambioseducativos e impacto del nuevo diseñocurricular en las prácticas pedagógicas

    Laparoscopic drainage of an ovarian haematoma in a Martina Franca jenny (Equus asinus)

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    An 11-year-old Martina Franca jenny (Equus Asinus), involved in a breed recovery programme organised by the Puglia Region, was referred to the University’s Veterinary Teaching Hospital for a mass formation detected on the surface of the right ovary. The subject had regular oestrous cycles, but gestation loss was reported in the anamnesis. The ovarian mass was monitored by transrectal palpation and ultrasonography. In the differential diagnosis, an ovarian haematoma, a haemorrhagic anovulatory follicle and a granulosa cell tumour were hypothesised; a surgical resolution with laparoscopic access was chosen. During surgery, about 750 ml of haemorrhagic fluid was drained, confirming the suspect of the ovarian haematoma. After resolution, the jenny was inseminated, eventually giving birth to a live and viable foal. Usually, an ovarian haematoma spontaneously regresses, but, in this report, the lesion remained stable for more than two months, leading to the decision of the surgical resolution. Furthermore, to the authors’ knowledge, this lesion has never been reported in donkeys

    Variações em atributos biofísicos e fisiológicos em nível de individuo e de parcela ao longo de um gradiente de densidade arbórea no Cerrado

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    O objetivo deste estudo foi caracterizar e compreender as variações morfológicas e fisiológicas em atributos relacionados à economia da água, em nível de indivíduo e de parcela, que ocorrem ao longo de um gradiente de densidade arbórea em uma savana neotropical (cerrado). Parcelas de vegetação de cerrado submetidas a um experimento de adubação de longo prazo e matas de galeria também foram incluídas na análise, a fim de expandir os eixos de variação do ecossistema. Mudanças consistentes em atributos biofísicos em nível de parcela foram observadas ao longo do gradiente de densidade crescente de árvores. Estas incluíram uma diminuição na densidade média ponderada da madeira, aumentos na área foliar por planta, na condutividade hidráulica específica da folha, na área foliar específica e na condutância estomática. Um modelo conceitual das interações entre as características biofísicas, morfológicas e fisiológicas foi desenvolvido em uma tentativa de explicar os determinantes da arquitetura hidráulica e variações na economia de água de árvores do Cerrado. Consistente com o modelo, os valores mínimos de potencial hídrico durante a estação seca foram maiores nas árvores de baixa densidade de madeira, em comparação com árvores de alta densidade de madeira, enquanto os maiores valores de potencial hídrico foliar estiveram associados com maior condutância estomática. Por outro lado, ao longo do gradiente de densidade arbórea, as variações em nível de parcela das características morfológicas e fisiológicas não puderam ser explicadas por variações de um único fator ambiental. Alguns dos fatores contribuintes potenciais são: maior concentração e disponibilidade de nutrientes do solo na porção superior do gradiente de densidade arbórea onde há um maior número de árvores e restrições no estabelecimento e crescimento pela inundação periódica e pela presença de concreções no perfil do solo onde a densidade de árvores é mais baixa.The objective of this study was to characterize and understand morphological and physiological variation in traits related to water economy, at the plant and stand level, along a gradient of tree density in a Neotropical savanna (Cerrado). Cerrado plots subjected to long-term fertilization and gallery forests were also included in the analysis to expand the axes of ecosystem variation. Consistent changes in stand level biophysical traits observed along the gradient of increasing tree density included a decrease in weighted-average wood density, and increases in leaf surface area per plant, leaf specific hydraulic conductivity, specific leaf area and stomatal conductance. A conceptual model of biophysical, morphological and physiological trait interactions was developed in an attempt to explain determinants of hydraulic architecture and variations in water economy of Cerrado trees. Consistent with the model minimum leaf water potentials were higher, during the dry season, in low wood density trees compared to high wood density trees, and higher leaf water potential was associated with higher stomatal conductance. On the other hand, variations in stand level physiological and morphological traits along the tree density gradient could not be explained by variations in single environmental factors. Some of the potential contributing factors are: higher concentration and availability of soil nutrients in the upper portion of the gradient where tree density is greatest and constrains to tree establishment and growth by waterlogging and presence of concretions in the soil profile where tree density is lowest

    Relações hídricas e arquitetura hidráulica em árvores do cerrado : adequação às variações sazonais de disponibilidade hídrica e de demanda evaporativa

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    O objetivo deste estudo foi determinar os ajustamentos na morfologia e fisiologia que permitem árvores das savanas neotropicais do Brasil Central (Cerrado) de evitar déficits hídricos e de manter um balanço hídrico interno praticamente constante apesar das variações sazonais da precipitação e no déficit de saturação do ar (D). A precipitação na área de estudo é fortemente sazonal, com cerca de cinco meses praticamente sem chuva durante os quais D é duas vezes maior aos valores medidos na época chuvosa. Como conseqüência da flutuação sazonal das chuvas e de D, o potencial hídrico do solo muda substancialmente, nos primeiros 100 cm do solo, mas permanece quase constante abaixo de 2 m de profundidade. A arquitetura hidráulica e os parâmetros relacionados a relações hídricas das árvores do Cerrado se ajustaram durante a estação seca para evitar o déficit hídrico crescente e assegurar a homeostase nos valores mínimos de potencial hídrico foliar ΨL e na perda total diária de água pela planta (iso-hidria). O comportamento iso-hídrico das árvores do Cerrado foi o resultado de uma diminuição da superfície foliar total por árvore, um forte controle estomático das perdas por evaporação, um aumento na condutividade hidráulica específica da folha e na condutância hidráulica foliar e um aumento da quantidade de águas retirada dos reservatórios internos do caule, durante a estação seca. A eficiência no transporte de água aumentou, nas mesmas proporções, nas folhas e nos ramos terminais durante a estação seca. Todos estes ajustamentos sazonais foram importantes para a manutenção de ΨL acima de limiares críticos, com isto contribuindo para uma redução na formação de embolismos nos ramos e ajudando a evitar a perda de turgor em tecidos foliares durante a época seca. Esses ajustes permitem que os ramos das espécies lenhosas do Cerrado operem bem distanciados do ponto de disfunção catastrófica para a cavitação, enquanto as folhas operam próximas e sofrem embolismos em uma base diária, especialmente durante a estação seca.We determined adjustments in physiology and morphology that allow Neotropical savanna trees from central Brazil (Cerrado) to avoid water deficits and to maintain a nearly constant internal water balance despite seasonal changes in precipitation and air saturation deficit (D). Precipitation in the study area is highly seasonal with about five nearly rainless months during which D is two fold higher compared to wet season values. As a consequence of the seasonal fluctuations in rainfall and D, soil water potential changes substantially in the upper 100 cm of soil, but remains nearly constant below 2 m depth. Hydraulic architecture and water relations traits of Cerrado trees adjusted during the dry season to prevent increasing water deficits and insure homeostasis in minimum leaf water potential ΨL and in total daily water loss per plant (isohydry). The isohydric behavior of Cerrado trees was the result of a decrease in total leaf surface area per tree, a strong stomatal control of evaporative losses, an increase in leaf-specific hydraulic conductivity and leaf hydraulic conductance and an increase in the amount of water withdrawn from internal stem storage, during the dry season. Water transport efficiency increased in the same proportion in leaves and terminal stems during the dry season. All of these seasonal adjustments were important for maintaining ΨL above critical thresholds, which reduces the rate of embolism formation in stems and help to avoid turgor loss in leaf tissues still during the dry season. These adjustments allow the stems of most Cerrado woody species to operate far from the point of catastrophic dysfunction for cavitation, while leaves operate close to it and experience embolism on a daily basis, especially during the dry season

    Maternal Phylogenetic Relationships and Genetic Variation among Rare, Phenotypically Similar Donkey Breeds

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    The mitochondrial DNA (mtDNA) D-loop of endangered and critically endangered breeds has been studied to identify maternal lineages, characterize genetic inheritance, reconstruct phylogenetic relations among breeds, and develop biodiversity conservation and breeding programs. The aim of the study was to determine the variability remaining and the phylogenetic relationship of Martina Franca (MF, with total population of 160 females and 36 males), Ragusano (RG, 344 females and 30 males), Pantesco (PT, 47 females and 15 males), and Catalonian (CT) donkeys by collecting genetic data from maternal lineages. Genetic material was collected from saliva, and a 350 bp fragment of D-loop mtDNA was amplified and sequenced. Sequences were aligned and evaluated using standard bioinformatics software. A total of 56 haplotypes including 33 polymorphic sites were found in 77 samples (27 MF, 22 RG, 8 PT, 19 CT, 1 crossbred). The breed nucleotide diversity value (π) for all the breeds was 0.128 (MF: 0.162, RG: 0.132, PT: 0.025, CT: 0.038). Principal components analysis grouped most of the haplogroups into two different clusters, I (including all haplotypes from PT and CT, together with haplotypes from MF and RG) and II (including haplotypes from MF and RG only). In conclusion, we found that the primeval haplotypes, haplogroup variability, and a large number of maternal lineages were preserved in MF and RG; thus, these breeds play putative pivotal roles in the phyletic relationships of donkey breeds. Maternal inheritance is indispensable genetic information required to evaluate inheritance, variability, and breeding programs

    Maternal Phylogenetic Relationships and Genetic Variation among Rare, Phenotypically Similar Donkey Breeds

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    The mitochondrial DNA (mtDNA) D-loop of endangered and critically endangered breeds has been studied to identify maternal lineages, characterize genetic inheritance, reconstruct phylogenetic relations among breeds, and develop biodiversity conservation and breeding programs. The aim of the study was to determine the variability remaining and the phylogenetic relationship of Martina Franca (MF, with total population of 160 females and 36 males), Ragusano (RG, 344 females and 30 males), Pantesco (PT, 47 females and 15 males), and Catalonian (CT) donkeys by collecting genetic data from maternal lineages. Genetic material was collected from saliva, and a 350 bp fragment of D-loop mtDNA was amplified and sequenced. Sequences were aligned and evaluated using standard bioinformatics software. A total of 56 haplotypes including 33 polymorphic sites were found in 77 samples (27 MF, 22 RG, 8 PT, 19 CT, 1 crossbred). The breed nucleotide diversity value (π) for all the breeds was 0.128 (MF: 0.162, RG: 0.132, PT: 0.025, CT: 0.038). Principal components analysis grouped most of the haplogroups into two different clusters, I (including all haplotypes from PT and CT, together with haplotypes from MF and RG) and II (including haplotypes from MF and RG only). In conclusion, we found that the primeval haplotypes, haplogroup variability, and a large number of maternal lineages were preserved in MF and RG; thus, these breeds play putative pivotal roles in the phyletic relationships of donkey breeds. Maternal inheritance is indispensable genetic information required to evaluate inheritance, variability, and breeding programs

    Sap flow and stomatal conductance of two evergreen woody species in an open savanna and a savanna woodland

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    No presente estudo, comparou-se o curso diário de fluxo de seiva, condutância estomática e potencial hídrico (psi) de duas espécies sempre-verdes, Rapanea guianensis e Roupala montana. Os dados foram obtidos no final da estação seca, quando os efeitos do déficit hídrico seriam mais acentuados. As medidas foram realizadas no campo sujo, onde predomina gramíneas com sistemas radiculares superficiais, e no cerradão, em que a maior densidade de elementos lenhosos com sistemas radiculares profundos poderia levar a um esgotamento das reservas de água do subsolo na estação seca. Valores máximos de psinão diferiram para as duas espécies nas duas fisionomias estudadas. Os valores mínimos de potencial hídrico foliar de R. guianensis foram mais negativos (P 0,05) entre os valores de fluxo máximo e de fluxo total entre o campo sujo e cerradão. Os valores máximos de fluxo de seiva variaram entre 0,13 e 0,22 l. h-1 para R. guianensis e entre 0,15 e 0,54 l. h-1 para R. montana. Entretanto, as duas espécies, tanto no campo sujo quanto no cerradão, apresentaram um rígido controle estomático em relação à alta demanda evaporativa da atmosfera. O fluxo de seiva aumentou bruscamente pela manhã, alcançando rapidamente valores máximos entre 8 e 10 horas, e logo após decresceu severamente, apesar do crescente aumento da radiação solar e da demanda evaporativa da atmosfera.The climate in the central Brazilian s savannas ("cerrados") is characterized by well-defined dry (May to September) and wet (October to April) seasons. Like other tropical savannas, a landscape mosaic forms the Brazilian savannas where the predominance and size of woody elements varies the most. The present study compared the daily course of sap flow, stomatal conductance and leaf water potential (psi) of two evergreen species, Rapanea guianensis and Roupala montana. The measurements were taken at the end of the dry season when the effects of water deficits are more intense. These measurements were taken in an open savanna area with a predominant grass layer with superficial root system ("campo sujo") and in a woodland savanna ("cerradão"), where the increase in density of deep-rooted trees result in a larger exploitation of soil water resources in the dry season. Maximum values of psidid not differ between the two species or the two vegetation types. R. guianensis minimum values of psi were significantly lower (P 0.05) between the "campo sujo" and the "cerradão" savannas. Maximum values of sap flow were between 0.13 and 0.22 l. h-1 for R. guianensis and 0.15 and 0.54 l. l. h-1 for R. montana. In both vegetation types the two species showed a strong stomatal control of transpiration. Sap flow typically increased sharply in the morning, briefly attained a maximum value by about 08.00-10.00h then decreased sharply despite steadily increasing solar radiation and atmospheric evaporative demand

    Local site effects estimation at Amatrice (Central Italy) through seismological methods

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    We present the results of seismological and geophysical investigations performed by the “Istituto Nazionale di Geofisica e Vulcanologia” team operating in Amatrice village (Central Italy), in the emergency phases following the Mw 6.0 event of August 24th 2016, that caused severe damage in downtown and surrounding areas. Data from seven seismic stations equipped with both weak and strong motion sensors are analyzed in terms of standard spectral ratio to empirically define amplification function using a bedrock reference site. Ambient vibration spectral ratios between horizontal and vertical component of motion are also evaluated in a large number of sites, spread out in the investigated area, to recover the resonance frequency of the soft soil outcropping layers and to generalize the results obtained by earthquake data. Ambient noise vibration are also used for applying a 2D array approach based on surface waves techniques in order to define the near-surface velocity model and to verify its lateral variation. The results allows to better understand the amplification factors in the investigated area, showing spatial variation of site effects despite of the homogeneous shallow geological condition indicated by the microzonation studies available at moment of the described field campaign. The analysis reveals a diffuse amplification effect which reaches its maximum values in downtown area with a resonant frequency of about 2 Hz. The obtained results were used to integrate the microzonation studies and they can be used for urban planning and reconstruction activities.Published5713–57394T. Sismicità dell'ItaliaJCR Journa

    Temporary dense seismic network during the 2016 Central Italy seismic emergency for microzonation studies

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    In August 2016, a magnitude 6.0 earthquake struck Central Italy, starting a devastating seismic sequence, aggravated by other two events of magnitude 5.9 and 6.5, respectively. After the first mainshock, four Italian institutions installed a dense temporary network of 50 seismic stations in an area of 260 km2. The network was registered in the International Federation of Digital Seismograph Networks with the code 3A and quoted with a Digital Object Identifier ( https://doi.org/10.13127/SD/ku7Xm12Yy9 ). Raw data were converted into the standard binary miniSEED format, and organized in a structured archive. Then, data quality and completeness were checked, and all the relevant information was used for creating the metadata volumes. Finally, the 99 Gb of continuous seismic data and metadata were uploaded into the INGV node of the European Integrated Data Archive repository. Their use was regulated by a Memorandum of Understanding between the institutions. After an embargo period, the data are now available for many different seismological studies.Publishedid 1825T. Sismologia, geofisica e geologia per l'ingegneria sismicaJCR Journa
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