874 research outputs found

    Past and Current Methods of Community Base Coastal Resources Management in the Southern Coast of Belize

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    The main problem definition of this study is the need to generate community-based management of coastal resources for the benefit of the small man and woman in the South Coast of Belize in opposition to the large scale and multinationally controlled shrimp aquaculture and banana agro-processing that have taken control of the area within the past two decades. So far the avenues for small-scale development which unlike large-scale investment, filter throughout the community, are artisanal fishery and tourism using the bountiful maritime, coastal, and riverine resources. By focusing on community-based coastal resource management in the past and present, the aim of the study is to show that there had been such a tradition in the past and that its review can help in re-introducing it at this time. In uncovering its data, the study used oral history, ethnography, and varied efforts of a collaborating NGO Toledo Institute for Development and the Environment (TIDE) in natural sciences data collection and community mobilization. Briefly the approach is that with negligible use of history, aesthetics, and cosmology, the community should work together to help diversify the national economy, conserve fishery, and maintain welcoming social structures for tourists visiting the marine protected areas

    Wireless internet architecture and testbed for wineglass

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    One of the most challenging issues in the area of mobile communication is the deployment of IPbased wireless multimedia networks in public and business environments. The public branch may involve public mobile networks, like UMTS as 3G system, while the business branch introduces local radio access networks by means of W-LANs. Conventional mobile networks realise mobile specific functionality, e.g. mobility management or authentication and accounting, by implementing appropriate mechanisms in specific switching nodes (e.g. SGSN in GPRS). In order to exploit the full potential of IP networking solutions a replacement of these mechanisms by IP-based solutions might be appropriate. In addition current and innovative future services in mobile environments require at least soft-guaranteed, differentiated QoS. Therefore the WINE GLASS project investigates and implements enhanced IP-based techniques supporting mobility and QoS in a wireless Internet architecture. As a means to verify the applicability of the implemented solutions, location-aware services deploying both IP-mobility and QoS mechanisms will be implemented and demonstratedPeer ReviewedPostprint (published version

    Efficient light-induced phase transitions in halogen-bonded liquid crystals

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    Here, we present a new family of light-responsive, fluorinated supramolecular liquid crystals (LCs) showing efficient and reversible light-induced LC-to-isotropic phase transitions. Our materials design is based on fluorinated azobenzenes, where the fluorination serves to strengthen the noncovalent interaction with bond-accepting stilbazole molecules, and increase the lifetime of the cis-form of the azobenzene units. The halogen-bonded LCs were characterized by means of X-ray diffraction, hot-stage polarized optical microscopy, and differential scanning calorimetry. Simultaneous analysis of light-induced changes in birefringence, absorption, and optical scattering allowed us to estimate that <4% of the mesogenic units in the cis-form suffices to trigger the full LC-to-isotropic phase transition. We also report a light-induced and reversible crystal-to-isotropic phase transition, which has not been previously observed in supramolecular complexes. In addition to fundamental understanding of light-responsive supramolecular complexes, we foresee this study to be important in the development of bistable photonic devices and supramolecular actuators

    House lot tenure in Barranco, Southern Belize. Opening the family chest

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    Records in private collections of rural dwellers are a significant source of information that remains untapped for ethnohistoric reconstruction. This study uses a little more than a hundred items, mainly house lot rental receipts. It starts by describing how the author was able to access the documents and overcome challenges in extracting the data. It follows with the contribution of the data to understanding house lot tenure in terms of the payment practices by villagers and the system of public lands administration; the overlap among kinship, lot tenure, and residence; and some anecdotes on the village community as part of the larger colonial society of 20th century Belize. In its analysis the paper shows that the Garifuna people are an ideal group for the study of lot tenure, having been formed through violent struggles for their lands in St. Vincent and their recurring forced movements by authorities within their communities in Central America. Finally, the data points to the critical role of women in assuming possession of house lots through de facto residence and exercising headship over household members.Los documentos existentes en manos de habitantes rurales constituyen una fuente significativa de información no explorada por la etnohistoria. Este estudio da cuenta de un poco más de cien documentos, principalmente recibos de renta. Inicia describiendo cómo le fue posible al autor acceder y superar retos en la extracción de datos. Continúa con la contribución de los datos para la comprensión de la tenencia de predios a partir de las prácticas de pago por parte de los habitantes del sistema público de administración de tierras; entendiéndose con ello, en mutuo acuerdo, la tenencia a través de la residencia. También se narran algunas anécdotas de la comunidad como parte de una sociedad colonial del Belice del siglo XX. En el análisis el artículo muestra que los garfunas son un grupo ideal para tal estudio, habiéndose constituido a través de violentas luchas por la tierra en St. Vincent y la recurrencia de movimientos forzados por las autoridades dentro de las comunidades en Centroamérica. Finalmente, los datos apuntan hacia un papel crítico de la mujer al asumir la posesión de los predios a través del establecimiento de la residencia y como cabeza de familia. &nbsp

    Estudo do Efeito de Parâmetros do Processo Gtaw Pulsado na Resistência à Corrosão Intergranular e Por Pite do Aço Inoxidável Duplex UNS S32304

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    Os aços inoxidáveis duplex, assim como os austeníticos e ferríticos, são susceptíveis à corrosão intergranular. O empobrecimento em cromo de regiões adjacentes aos precipitados que podem ser formados nesses aços é o mecanismo mais aceito para descrever tal fenômeno. Processos de soldagem e tratamentos térmicos podem causar tal mecanismo e costuma-se dizer que o material se encontra sensitizado. Os processos de soldagem geram ciclos térmicos não homogêneos e isso faz com que o material passe por transformações microestruturais muitas vezes indesejadas. Regiões próximas à zona fundida (ZF) são consideradas como críticas devido ao favorecimento da precipitação de microconstituintes e novas fases. A chamada zona termicamente afetada (ZTA) pode sofrer ciclo térmico numa faixa de temperatura que favoreça a cinética de formação de novas fases. Vários processos industriais adotam um tratamento térmico posterior à soldagem, para minimizar ou até extinguir tais efeitos. Neste trabalho buscou-se avaliar o efeito de parâmetros do processo de soldagem GTAW (Gas Tungsten Arc Weld) pulsado sobre as resistências à corrosão por pites e intergranular de um aço inoxidável duplex UNS S32304. Para isso, foram realizadas curvas de polarização e empregou-se o método de reativação eletroquímica potenciodinâmica na versão ciclo duplo (DL-EPR). Foram obtidos dez cordões de solda, por meio de fusão, sem deposição de material sobre chapas do aço estudado. Uma condição estudada foi o GTAW convencional, e os parâmetros avaliados no processo pulsado foram as freqüências, entre 1 e 4 Hz, e a relação do tempo de pulso no tempo (pulse on time). As propriedades mecânicas foram avaliadas pelo ensaio de microdureza e a caracterização microestrutural do material foi efetuada por microscopia óptica e eletrônica de varredura. As regiões soldadas apresentaram menor susceptibilidade à corrosão intergranular quando comparadas ao metal base (MB). E esse por sua vez apresentou um potencial de pite superior às demais. A formação de precipitados na ZTA não causou um efeito drástico na resistência à corrosão intergranular, mas por outro lado, a resistência à corrosão por pite foi prejudicada

    Temperature dependence of antiferromagnetic susceptibility in ferritin

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    We show that antiferromagnetic susceptibility in ferritin increases with temperature between 4.2 K and 180 K (i. e. below the N\'{e}el temperature) when taken as the derivative of the magnetization at high fields (30×10430\times10^4 Oe). This behavior contrasts with the decrease in temperature previously found, where the susceptibility was determined at lower fields (5×1045\times10^4 Oe). At high fields (up to 50×10450 \times10^4 Oe) the temperature dependence of the antiferromagnetic susceptibility in ferritin nanoparticles approaches the normal behavior of bulk antiferromagnets and nanoparticles considering superantiferromagnetism, this latter leading to a better agreement at high field and low temperature. The contrast with the previous results is due to the insufficient field range used (<5×104< 5 \times10^4 Oe), not enough to saturate the ferritin uncompensated moment.Comment: 7 pages, 7 figures, accepted in Phys. Rev.

    Hierarchical Self-Assembly of Halogen-Bonded Block Copolymer Complexes into Upright Cylindrical Domains

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    Self-assembly of block copolymers into well-defined, ordered arrangements of chemically distinct domains is a reliable strategy for preparing tailored nanostructures. Microphase separation results from the system, minimizing repulsive interactions between dissimilar blocks and maximizing attractive interactions between similar blocks. Supramolecular methods have also achieved this separation by introducing small-molecule additives binding specifically to one block by noncovalent interactions. Here, we use halogen bonding as a supramolecular tool that directs the hierarchical self-assembly of low-molecular-weight perfluorinated molecules and diblock copolymers. Microphase separation results in a lamellar-within-cylindrical arrangement and promotes upright cylindrical alignment in films upon rapid casting and without further annealing. Such cylindrical domains with internal lamellar self-assemblies can be cleaved by solvent treatment of bulk films, resulting in separated and segmented cylindrical micelles stabilized by halogen-bond-based supramolecular crosslinks. These features, alongside the reversible nature of halogen bonding, provide a robust modular approach for nanofabricatio

    Gut microbiota in canine idiopathic epilepsy: Effects of disease and treatment

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    Epilepsy is one of the most common neurological disorders in humans and dogs. The structure and composition of gut microbiome associated to this disorder has not yet been analyzed in depth but there is evidence that suggests a possible influence of gut bacteria in controlling seizures. The aim of this study was to investigate the changes in gut microbiota associated to canine idiopathic epilepsy (IE) and the possible influence of antiepileptic drugs (AEDs) on the modulation of this microbiota. Faecal microbiota composition was analyzed using sequencing of bacterial 16S rRNA gene in a group of healthy controls (n = 12) and a group of epileptic dogs both before (n = 10) and after a 30-day single treatment with phenobarbital or imepitoin (n = 9). Epileptic dogs showed significantly reduced abundance of GABA (Pseudomonadales, Pseudomonadaceae, Pseudomonas and Pseudomona_graminis) and SCFAs-producing bacteria (Peptococcaceae, Ruminococcaceae and Anaerotruncus) as well as bacteria associated with reduced risk for brain disease (Prevotellaceae) than control dogs. The administration of AEDs during 30 days did not modify the gut microbiota composition. These results are expected to contribute to the understanding of canine idiopathic epilepsy and open up the possibility of studying new therapeutic approaches for this disorder, including probiotic intervention to restore gut microbiota in epileptic individuals. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

    Shifted loops and coercivity from field imprinted high energy barriers in ferritin and ferrihydrite nanoparticles

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    We show that the coercive field in ferritin and ferrihydrite depends on the maximum magnetic field in a hysteresis loop and that coercivity and loop shifts depend both on the maximum and cooling fields. In the case of ferritin we show that the time dependence of the magnetization also depends on the maximum and previous cooling fields. This behavior is associated to changes in the intra-particle energy barriers imprinted by these fields. Accordingly, the dependence of the coercive and loop shift fields with the maximum field in ferritin and ferrihydrite can be described within the frame of a uniform-rotation model considering a dependence of the energy barrier with the maximum and the cooling fields.Comment: 8 pages, 5 figures. Accepted for publication in Phys. Rev. B. Final version with improved writing and figure
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