201 research outputs found

    Income Taxation - Gift and Leaseback Schemes

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    Estimating critical abundance thresholds in exploited populations: a simulation approach based on species resilience to disturbance

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    Managers of exploited species too often assume that populations can be maintained at equilibrium abundances that will provide maximum yield. Most evidence to date suggests that populations seldom adhere to equilibria, but rather fluctuate stochastically between bounds. The last decade has revealed the consequences of not incorporating uncertainty around point estimates of equilibria, which has led to the decline of several fisheries. We used the sample importance re-sampling (SIR) algorithm to exhibit the uncertainties in point estimates generated by models for management of two Chinook salmon Oncorhynchus tshawytscha stocks and a bowhead whale Balaena mysticetus population. We then incorporated the cumulative uncertainties of each system into a simulation technique similar to population viability analyses (PVA) to provide decision support for establishing threshold abundances of each exploited population. The simulation presented was based upon the resilience (time to recover from perturbations to abundance) of each population, which was found to be relatively high for the Chinook stocks and low for bowhead whale. Various thresholds could be chosen depending on: (1) how much time should be allowed for the population to recover from a perturbation, (2) when should the stock be considered recovered (i.e., within 1%, 5%, 10%, and so on of what abundance would be had there been no perturbation), and (3) the maximum allowable risk that a threshold is too low. Reasonable thresholds for the Chinook stocks were 60% to 80% of abundances that provide maximum sustained yield (SMSY). Due to their low productivity, no clear threshold below the biomass point estimate was apparent for bowhead whale

    The 13th Compound: Co-operative development of an industrial urban village

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    This thesis critiques the tabula rasa typology of 'slum' redevelopment which utilizes master planning to erase and rebuild slums. It proposes to enact a system based on smaller, contextual intervention within the 13 th Compound in the Dharavi slum of Mumbai. Focusing on the creation of trade based workers' co-operatives; this thesis intends to reinforce the 13th Compound and its symbiotic relationship to Mumbai. The proposal utilizes the context and resources of the neighborhood while focusing on the existing recycling industry as a continued means of livelihood. By enacting smaller scale interventions through erasure and addition, it inserts trade based workers' co-operatives as a means of organization, both spatially and politically. These co-operatives will represent the recycling trader which thrive in the 13th Compound and will integrate infrastructural amenities such as rain-water harvesting and gray water filtration into the existing industrial fabric in order to facilitate continual development

    Cannabinoid Modulation of Chemotaxis of Macrophages and Macrophage-like Cells

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    Exogenous and endogenous cannabinoids have been reported to modulate functional activities of macrophages. It is recognized that macrophages express primarily the CB2 cannabinoid receptor, but recent studies indicate that its expression is differential in relation to activation state with maximal levels occurring when cells are in responsive and primed states. The functional activities of macrophages when in these states of activation are the most susceptible to the action of cannabinoids, at least in terms of a functional linkage to the CB2. To assess the effect of cannabinoid treatment on macrophage chemotaxis and test the hypothesis that cannabinoids inhibit the chemotactic response of macrophages and microglia to endogenous and exogenous, pathogen-derived stimuli, primary murine peritoneal macrophages and neonatal rat microglia were used. Chemotaxis assays and scanning electron microscopy studies demonstrated that cannabinoids inhibit chemotaxis, a signature activity attributed to responsive macrophage-like cells, to the endogenous chemokine RANTES (Regulated upon Activation Normal T-cell Expressed and Secreted) and to Acanthamoeba conditioned medium containing secreted proteases. The partial agonist delta-9-tetrahydrocannabinol (THC), administered in vitro, inhibited the chemotactic response of peritoneal macrophages to the chemokine RANTES and to Acanthamoeba conditioned medium. In vivo treatment with THC also resulted in inhibition of the in vitro chemotactic response of murine peritoneal macrophages to RANTES and amoebic conditioned medium. Pharmacological studies employing cannabinoid receptor agonists and antagonists demonstrated the involvement of CB2 in cannabinoid-mediated inhibition of peritoneal macrophage chemotaxis to RANTES and Acanthamoeba conditioned medium, implying that signaling through cannabinoid receptors may desensitize chemokine receptors. Treatment with cannabinoids had no apparent effect on chemokine receptor mRNA levels, but did enhance CCR5 protein phosphorylation. Macrophage migration to Acanthamoeba conditioned medium may involve activation and signaling through protease activated receptors (PARs), as pathogen-derived proteases have been shown to activate PARs and initiate cellular migration; however, further studies are required to demonstrate PAR activation by amoebic conditioned medium and to assess the effects of cannabinoids on PAR signaling. Acanthamoeba are opportunistic pathogens that cause Granulomatis amoebic encephalitis, an infection of the CNS that is often fatal. THC treatment has been shown to increase mortality to Acanthamoeba infections and is characterized by an absence of granuloma formation. We hypothesize that inhibitory effect of THC on macrophage migration may be a key factor in cannabinoid-mediated immunosuppression. To assess the effect of cannabinoids on microglial migration to Acanthamoeba conditioned medium, chemotaxis assays were performed using primary rat microglia treated with cannabinoids. These studies demonstrated that cannabinoids inhibit microglial chemotaxis to amoebic conditioned medium. Furthermore, the studies demonstrate that cannabinoids, acting through cannabinoid receptors, may cross-talk with a diverse array G-protein coupled receptors so as to modulate responsiveness of macrophage and macrophage-like cells

    A new reference genome assembly for the microcrustacean Daphnia pulex

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    Comparing genomes of closely related genotypes from populations with distinct demographic histories can help reveal the impact of effective population size on genome evolution. For this purpose, we present a high quality genome assembly of Daphnia pulex (PA42), and compare this with the first sequenced genome of this species (TCO), which was derived from an isolate from a population with >90% reduction in nucleotide diversity. PA42 has numerous similarities to TCO at the gene level, with an average amino acid sequence identity of 98.8 and >60% of orthologous proteins identical. Nonetheless, there is a highly elevated number of genes in the TCO genome annotation, with similar to 7000 excess genes appearing to be false positives. This view is supported by the high GC content, lack of introns, and short length of these suspicious gene annotations. Consistent with the view that reduced effective population size can facilitate the accumulation of slightly deleterious genomic features, we observe more proliferation of transposable elements (TEs) and a higher frequency of gained introns in the TCO genome

    Changes in Fish Catch Rates in the Presence of Air Gun Sounds in Prudhoe Bay, Alaska

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    Air guns used in oil industry seismic surveys have the capacity to change fish catch rates, but no previous work has demonstrated this effect in shallow water or in Arctic oilfields. Long-term monitoring of fish catches using four fyke nets allowed assessment of changes in catch rates during a 2014 seismic survey in Prudhoe Bay, Alaska. Fyke net locations were instrumented with both conventional hydrophones and vector sensors. Catch rates were generally within the range of those found in 27 previous sampling seasons. The effect of air guns on eight species was assessed using a modified Before-After/Control-Impact analysis, with historical data and 2014 data as the Before-After components of the analysis and days without and with air gun activity as the Control-Impact components. Results showed significant changes associated with air guns in catch rates at one or more nets at p < 0.1 for all eight species and at p < 0.05 for seven of the eight. Changes included both increased and decreased catch rates, perhaps reflecting displacement of fish in response to air gun sounds throughout the study area. Measured sound pressure levels associated with air gun pulses were low and usually undetectable close to the fyke nets, reflecting the loss of low frequencies in shallow water (~1.5 m). Attempts to measure particle velocities failed when wind-driven surface waves overwhelmed vector sensors. However, fish responses may have been related to changes in particle motion associated with air gun sounds.Les armes à air comprimé dont on se sert pour faire les levés sismiques dans l’industrie pétrolière ont la capacité de changer le taux de capture des poissons, mais aucune étude n’a jamais démontré l’effet de ces armes dans les eaux peu profondes ou dans les champs pétrolifères de l’Arctique. La surveillance à long terme des prises de poissons à l’aide de quatre verveux a permis d’évaluer les changements en matière de taux de prises pendant un levé sismique qui a eu lieu à Prudhoe Bay, Alaska, en 2014. Les emplacements de verveux ont été munis d’hydrophones classiques et de capteurs de vecteur. De manière générale, les taux de prises coïncidaient avec la gamme répertoriée au cours des 27 saisons d’échantillonnage précédentes. L’effet des armes à air comprimé sur huit espèces a été évalué au moyen d’une analyse modifiée avant-après/contrôle-impact, les données historiques et les données de 2014 représentant les composantes avant-après de l’analyse, puis les jours avec et les jours sans activité d’armes à air comprimé représentant les composantes contrôle-impact de l’analyse. Les résultats ont permis de constater d’importants changements liés à l’emploi d’armes à air comprimé pour ce qui est des taux de prises à un ou plusieurs verveux, à p < 0,1 pour les huit espèces, et à p < 0,05 pour sept des huit espèces. Les changements se sont caractérisés à la fois par des taux de prises plus élevés et moins élevés, ce qui reflétait peut-être le déplacement des poissons en raison du son des armes à air comprimé dans la zone visée par l’étude. Les niveaux de pression sonore mesurés en lien avec les impulsions d’armes à air comprimé étaient faibles et habituellement indétectables à proximité des verveux, signe de la perte des ondes kilométriques dans l’eau peu profonde (~1,5 m). Les tentatives de mesure des vitesses acoustiques des particules ont échoué lorsque les ondes de surface poussées par le vent submergeaient les capteurs de vecteur. Toutefois, la réaction des poissons aurait pu être liée aux changements sur le plan du mouvement des particules découlant du son des armes à air comprimé
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