Avaliação de desempenho de protótipo de secador solar passivo para tratamento de efluente de processo de dessalinização por destilação multi-efeito

O projecto AQUASOL-Enhanced Zero Discharge Seawater Desalination using Hybrid Solar Technology (EVK1-CT2001-00102) teve como principais objectivos a melhoria do desempenho económico e a minimização dos impactes ambientais associados a um processo de dessalinização por Destilação Multi-Efeito (MED)(Blanco et al, 2002). No âmbito do projecto, decorre o estudo de um secador solar passivo utilizado no tratamento do efluente produzido no processo de dessalinização, salmoura, através da sua concentração e/ou através da produção directa de sal a partir do efluente. Nesta etapa adicional do processo de dessalinização foi considerada não só a maior concentração do efluente relativamente à concentração da água marinha utilizada no processo MED, mas também a sua possível integração numa salina tradicional, com o potencial de substituir etapas intermédias da evaporação com vantagem face ao processo convencional de produção de sal marinho. Após um estudo das especificidades da produção de sal em Salinas tradicionais e do processo de evaporação de uma camada de salmoura, a construção e avaliação de cinco configurações distintas de um protótipo preliminar de secador solar passivo, permitiu o desenho final de um secador para a recuperação de sal a partir do efluente do processo MED (Collares Pereira et al, 2004), construido numa salina industrial na ilha de Lesvos (Grécia) (Collares Pereira et al, 2005). Neste artigo serão apresentados os primeiros resultados de operação do protótipo, bem como uma avaliação inicial do seu desempenho

Overcoming inertia : drivers of the outsourcing process

Almost all managers have directly or indirectly been involved in the practice of outsourcing in recent years. But as they know, outsourcing is not straightforward. Outsourcing inertia, when companies are slow to adapt to changing circumstances that accommodate higher outsourcing levels, may undermine a firm’s performance. This article investigates the presence of outsourcing inertia and the factors that help managers overcome it. Using statistical evidence, we show that positive performance effects related to outsourcing can accumulate when circumstances change. This is then followed by rapid increases in outsourcing levels (i.e. outsourcing processes). We investigate what gives rise to these outsourcing processes through follow-up interviews with sourcing executives, which suggest five drivers behind outsourcing processes: managerial initiative (using outside experience); hierarchy (foreign headquarters); imitation (of competitors and of similar firms); outsider advice (from external institutions); knowledge sources (using external information). These five drivers all offer scope for managerial action. We tie them to academic literatures and suggest ways of investigating their presence and impact on the outsourcing process. Overall, we conclude that while economizing factors play a key role in explaining how much firms outsource, it is socializing factors that tend to drive outsourcing processes

Bone length of lberian freshwater fish, as a predictor of length and biomass of prey consumed by piscivores

We measured various fish bones from 13 Iberian freshwater fish species and one hybrid species. Original total body lengths were then back-calculated using bone measurements. Bones usually found in prey remains left by piscivorous predators, were usually from the head skeleton and from the vertebral column. The 73 regressions obtained between bone length and fish length were linear for al1 species examined. Coefficients of determination ranged between 75.6 % and 99.5 %. To estimate fish biomass, length-weight relations were used for each species, too. Bone length vs. fish length relationships found in the literature for seven additional species inhabiting the Iberian Peninsula were also included, totalling 29 regression equations. The amount of dietary information available from fish predator remains can be greatly increased by using these relationships. In this paper, information is provided covering in excess of 37 YO of lberian freshwater fish fauna, including the most abundant and widespread species.-----------------------------------------------------------------------Se han realizado medidas a 13 tipos de huesos de peces para retrocalcular su longitud total. Estos huesos, que se encuentran normalmente en los restos dejados por depredadores ictiófagos, pertenecen al esqueleto de la cabeza y a la columna vertebral de 13 especies de peces (más un híbrido) de aguas continentales de la Península Ibérica. Las 73 ecuaciones obtenidas entre la longitud del hueso y la del pez fueron lineales para todas las especies estudiadas; los coeficientes de determinación oscilaron entre el 75.6 %y el 99.5 %. Para la estimación de la biomasa de los peces se han calculado las regresiones longitud- peso para cada una de las especies. Además, se incluyen, extraídas de la bibliogra$a, las relaciones entre la longitud del hueso y la longitud del pez para otras siete especies de peces que habitan en la Península Ibérica. Con este método la cantidad de información extraíble del análisis de la dieta de depredadores ictiófagos se puede incrementar considerablemente. Las ecuaciones que se aportan abarcan a más del 37 96 de la ictiofauna Ibérica de aguas continentales, con inclusión de las especies más abundantes y de más amplia distribución

A thermal-optical analysis of a compound parabolic concentrator for single and multiphase flows, including superheat

A thermal and optical analysis of the performance of a refrigerant charged Compound Parabolic Concentrator (CPC) for solar applications operating in non-boiling, boiling and super-heated regimes is presented. The performance of the CPC working under these single and multiphase conditions is governed by the axial fractional channel lengths of the non-boiling and the superheating regions. The overall thermal loss coefficient, the dimensionless capacitance rate and collector efficiency factors for various CPC operating regions are defined. A new “Generalized Heat Removal Factor“, ℱ s for solar collectors under any operation mode is developed. The thermal efficiency of a CPC and flat-plate collector, whether under non-boiling, boiling or superheated conditions, is evaluated using ℱ s which enables the selection of a suitable collector design and concentration ratio at some specified operational temperature. It is shown that, in general, a CPC has a greater thermal conversion efficiency than a flat-plate for a given operating condition. Es wird eine thermische und optische Analyse des Verhaltens eines Verbund-Parabol-Kollektors für die Anwendung der Sonnenenergie vorgestellt, der mit Kältemittel im nichtsiedenden, und übehitzten Bereich arbeitet. Das Verhalten dieses unter ein- und mehrphasigen Bedingungen arbeitenden Kollektors wird bestimmt durch den axialen Anteil der Kühl-kanallängen im nichtsiedenden und im überhitzten Zustand. Es werden der mittlere thermische Verlustkoeffizient, die dimensionslose Wärmekapazität sowie die Kollektorwirkungsgrade für verschiedene Zustandsbereiche dieses Parabolspiegels definiert. Ein neuer „verallgemeinerter Wärmeabflußfaktor“, ℱ s , für Sonnenkollektoren, die unter beliebigen Betriebsbedingungen arbeiten, wurde entwickelt. Mit diesem ℱ s Faktor werden der thermische Wirkungsgrad des Parabolkollektors und eines Platten-kollektors bei einphasiger flüssiger Strömung beim Sieden und für überhitzten Dampf berechnet, wodurch es möglich wird, eine geeignete Kollektorauslegung und das dazugehörige Konzentrationsverhältnis bei vorgegebenen Betriebstemperaturen zu wählen. Es wird gezeigt, daß im allgemeinen der parabolische Kollektor einen höheren thermischen Wirkungsgrad besitzt als der Platten-kollektor bei identischen Betriebsbedingungen.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46656/1/231_2005_Article_BF01377577.pd

Reproductive success of nuclear nonhybrid males of Squalius alburnoides hybridogenetic complex (Teleostei, Cyprinidae): An example of interplay between female choice and ecological pressures?

The hybridogenetic fish complex Squalius alburnoides comprises diploid males with non-hybrid nuclear genomes and several hybrid forms varying in ploidy and relative proportions of the parental genomes. In this paper, we present evidence that in captivity females prefer to mate with non-hybrid males. We suggest that female choice combined with different ecological requirements of hybrid and non-hybrid males may explain the extreme variation in the relative abundance of male types among drainages

Prioritization of fish communities with a view to conservation and restoration on a large scale European basin, the Loire (France)

The hierarchical organization of important sites for the conservation or the restoration of fish communities is a great challenge for managers, especially because of financial or time constraints. In this perspective, we developed a methodology, which is easy to implement in different locations. Based on the fish assemblage characteristics of the Loire basin (France), we created a synthetic conservation value index including the rarity, the conservation status and the species origin. The relationship between this new synthetic index and the Fish-Based Index allowed us to establish a classification protocol of the sites along the Loire including fish assemblages to be restored or conserved. Sites presenting disturbed fish assemblages, a low rarity index, few threatened species, and a high proportion of non-native species were considered as important for the restoration of fish biodiversity. These sites were found mainly in areas where the assemblages are typical of the bream zone, e.g. with a higher number of eurytopic and limnophilic species. On the contrary, important sites for conservation were defined as having an important conservation potential (high RI, a lot of threatened species, and few nonnatives fish species) and an undisturbed fish assemblage similar to the expected community if habitats are undisturbed. Important sites for conservation were found in the Loire basin’s medium reaches which host assemblages typical for the grayling and the barbell zones, e.g. with a higher number of rheophilic species. The synthetic conservation value index could be adapted and completed with other criteria according to management priorities and capacities

Borrelia valaisiana resist complement-mediated killing independently of the recruitment of immune regulators and inactivation of complement components

Spirochetes belonging to the Borrelia (B.) burgdorferi sensu lato complex differ in their resistance to complement-mediated killing, particularly in regard to human serum. In the present study, we elucidate the serum and complement susceptibility of B. valaisiana, a genospecies with the potential to cause Lyme disease in Europe as well as in Asia. Among the investigated isolates, growth of ZWU3 Ny3 was not affected while growth of VS116 and Bv9 was strongly inhibited in the presence of 50% human serum. Analyzing complement activation, complement components C3, C4 and C6 were deposited on the surface of isolates VS116 and Bv9, and similarly the membrane attack complex was formed on their surface. In contrast, no surface-deposited components and no aberrations in cell morphology were detected for serum-resistant ZWU3 Ny3. While further investigating the protective role of bound complement regulators in mediating complement resistance, we discovered that none of the B. valaisiana isolates analyzed bound complement regulators Factor H, Factor H-like protein 1, C4b binding protein or C1 esterase inhibitor. In addition, B. valaisiana also lacked intrinsic proteolytic activity to degrade complement components C3, C3b, C4, C4b, and C5. Taken together, these findings suggest that certain B. valaisiana isolates differ in their capability to resist complement-mediating killing by human serum. The molecular mechanism utilized by B. valaisiana to inhibit bacteriolysis appears not to involve binding of the key host complement regulators of the alternative, classical, and lectin pathways as already known for serum-resistant Lyme disease or relapsing fever borreliae

Fine-Scale Phylogeographic Structure of Borrelia lusitaniae Revealed by Multilocus Sequence Typing

Borrelia lusitaniae is an Old World species of the Lyme borreliosis (LB) group of tick-borne spirochetes and prevails mainly in countries around the Mediterranean Basin. Lizards of the family Lacertidae have been identified as reservoir hosts of B. lusitaniae. These reptiles are highly structured geographically, indicating limited migration. In order to examine whether host geographic structure shapes the evolution and epidemiology of B. lusitaniae, we analyzed the phylogeographic population structure of this tick-borne bacterium using a recently developed multilocus sequence typing (MLST) scheme based on chromosomal housekeeping genes. A total of 2,099 questing nymphal and adult Ixodes ricinus ticks were collected in two climatically different regions of Portugal, being ∼130 km apart. All ticks were screened for spirochetes by direct PCR. Attempts to isolate strains yielded 16 cultures of B. lusitaniae in total. Uncontaminated cultures as well as infected ticks were included in this study. The results using MLST show that the regional B. lusitaniae populations constitute genetically distinct populations. In contrast, no clear phylogeographic signals were detected in sequences of the commonly used molecular markers ospA and ospC. The pronounced population structure of B. lusitaniae over a short geographic distance as captured by MLST of the housekeeping genes suggests that the migration rates of B. lusitaniae are rather low, most likely because the distribution of mediterranean lizard populations is highly parapatric. The study underlines the importance of vertebrate hosts in the geographic spread of tick-borne microparasites