Decentralized Provision Of Public Goods

When individuals provide noncooperatively many public goods, not only are contribution levels generally too low, but the composition of the contributions is also generally inefficient. Efficiency gains may then be obtained through institutions that constrain individuals\u27 choices, either by increasing contribution levels and/or by improving the public goods mix.;A model of noncooperative public goods provision is set up in chapter 1. The presence of many public goods presents an additional difficulty because the theory of demand under rationing (instead of standard consumer theory) is needed to derive individuals\u27 contribution functions. The impact of various institutions on individuals\u27 choice sets is shown and a taxonomy is proposed.;In chapter 2, a United Fund is added as an autonomous player that collects charitable contributions and redistributes them to various charities. Necessary and sufficient conditions for contributing to the United Fund to be a Subgame Perfect Equilibrium strategy are found. It is also shown that contributions to a United Fund would likely be smaller than direct contributions to charities would have been, raising a mix-level dilemma for the Funds\u27 administrators.;In chapter 3, a tax-earmarking scheme, where individuals must pay some tax but may earmark it to the provision of any public good, is analysed. It is shown that when there are only two public goods, the tax-earmarking outcome is particularly attractive since it is always unique, constrained pareto-efficient, and in the constrained core.;In chapter 4, subsidy schemes for private provision of public goods are analysed. It is shown that Lindahl equilibria are the only efficient allocations that may be supported as Nash equilibria where everyone contributes positively and that a uniform subsidy rate would generally be inefficient

Understanding food web mercury accumulation through trophic transfer and carbon processing along a river affected by recent run-of-river dams

Unlike large dams which favor methylation of Hg in flooded soils over long periods, run-of-river dams are designed to flood a limited area of soils and are therefore not expected to significantly affect mercury (Hg) cycling or carbon processing. We studied the Hg and carbon cycles within food webs from several sectors along the Saint-Maurice River, Quebec, Canada, that differ in how they are influenced by two run-of-river dams and other watershed disturbances. We observed peak Hg concentrations in fish five-year postimpoundment, but these levels were reduced three years after this peak. Methylmercury concentrations in low trophic level fish and invertebrates were related to their carbon source (δ13C) rather than their trophic positions (δ15N). Biomagnification, measured by trophic magnification slopes, was driven mainly by methylmercury concentrations in low-trophic level organisms and environmental factors related to organic matter degradation and Hg-methylation. River sectors, δ13C and δ15N, predicted up to 80% of the variability in food web methylmercury concentrations. The installation of run-of-river dams and the related pondages, in association with other watershed disturbances, altered carbon processing, promoted Hg-methylation and its accumulation at the base of the food web, and led to a temporary increase in Hg levels in fish

The neurobiology of speech perception decline in aging

Speech perception difficulties are common amongst elderlies; yet the underlying neural mechanisms are still poorly understood. New empirical evidence suggesting that brain senescence may be an important contributor to these difficulties have challenged the traditional view that peripheral hearing loss was the main factor in the aetiology of these difficulties. Here we investigated the relationship between structural and functional brain senescence and speech perception skills in aging. Following audiometric evaluations, participants underwent MRI while performing a speech perception task at different intelligibility levels. As expected, with age speech perception declined, even after controlling for hearing sensitivity using an audiological measure (pure tone averages), and a bioacoustical measure (DPOAEs recordings). Our results reveal that the core speech network, centered on the supratemporal cortex and ventral motor areas bilaterally, decreased in spatial extent in older adults. Importantly, our results also show that speech skills in aging are affected by changes in cortical thickness and in brain functioning. Age-independent intelligibility effects were found in several motor and premotor areas, including the left ventral premotor cortex and the right SMA. Agedependent intelligibility effects were also found, mainly in sensorimotor cortical areas, and in the left dorsal anterior insula. In this region, changes in BOLD signal had an effect on the relationship of age to speech perception skills suggesting a role for this region in maintaining speech perception in older ages perhaps by. These results provide important new insights into the neurobiology of speech perception in aging

Mobilization and transformation of mercury across a dammed boreal river are linked to carbon processing and hydrology

Reservoirs are known to accelerate the mobilization and cycling of mercury and carbon as aresult of flooding of terrestrial organic matter, which can lead to environmental concerns at local andbroader spatial scales. We explored the covariation of mercury (Hg) and carbon (C) functional pools innatural and recently dammed portions of the aquatic network of the Romaine River watershed in NorthernQuebec, Canada, to understand how the fate of these elements varies across systems with contrastinghydrology and environmental conditions. We found that total Hg (THg) concentrations in surface waterswere relatively constant along the network, whereas both the concentrations and proportions of MeHgtended to increase in reservoirs compared to surrounding nonooded systems, and along the cascade ofreservoirs. Whereas THg was related to total and terrestrial pools of dissolved organic carbon (DOC), MeHgwas weakly related to DOC but strongly linked to surface concentrations of CO2, as well as toconcentrations of iron and manganese. The latter are proxies of cumulative organic matter processing withinthe network, presumably in anoxic portions of shallow bays, deep reservoir waters, and river sediments,as well as in prior seasons (e.g., under ice). Our results suggest that these deep boreal reservoirs acted more astransformation sites for Hg that was already present than as mobilizers of new Hg, and that under icemetabolism plays a role in MeHg production in these systems as we found strong dichotomies in MeHgpatterns between spring and summer

An amplicon-based sequencing approach for the study of aeromycology

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Применение активной молниезащиты, как способ повышения уровня безопасности промышленной площадки

В данной работе автором проводится разработка инженерно-технических мероприятий направленных на повышение уровня безопасности промышленной площадки эксплуатирующей природный газ действующего производства города Томск.In the paper author presents the development of measures aimed at the improving safety level of the Tomsk ongoing production gas operating industrial site

Cell arrest and cell death in mammalian preimplantation development

The causes, modes, biological role and prospective significance of cell death in preimplantation development in humans and other mammals are still poorly understood. Early bovine embryos represent a very attractive experimental model for the investigation of this fundamental and important issue. To obtain reference data on the temporal and spatial occurrence of cell death in early bovine embryogenesis, three-dimensionally preserved embryos of different ages and stages of development up to hatched blastocysts were examined in toto by confocal laser scanning microscopy. In parallel, transcript abundance profiles for selected apoptosis-related genes were analyzed by real-time reverse transcriptase-polymerase chain reaction. Our study documents that in vitro as well as in vivo, the first four cleavage cycles are prone to a high failure rate including different types of permanent cell cycle arrest and subsequent non-apoptotic blastomere death. In vitro produced and in vivo derived blastocysts showed a significant incidence of cell death in the inner cell mass (ICM), but only in part with morphological features of apoptosis. Importantly, transcripts for CASP3, CASP9, CASP8 and FAS/FASLG were not detectable or found at very low abundances. In vitro and in vivo, errors and failures of the first and the next three cleavage divisions frequently cause immediate embryo death or lead to aberrant subsequent development, and are the main source of developmental heterogeneity. A substantial occurrence of cell death in the ICM even in fast developing blastocysts strongly suggests a regular developmentally controlled elimination of cells, while the nature and mechanisms of ICM cell death are unclear. Morphological findings as well as transcript levels measured for important apoptosis-related genes are in conflict with the view that classical caspase-mediated apoptosis is the major cause of cell death in early bovine development