Macnamara\u27s band

https://digitalcommons.library.umaine.edu/mmb-vp/2057/thumbnail.jp

Sustainability of UK shale gas in comparison with other electricity options: Current situation and future scenarios.

Many countries are considering exploitation of shale gas but its overall sustainability is currently unclear. Previous studies focused mainly on environmental aspects of shale gas, largely in the US, with scant information on socio-economic aspects. To address this knowledge gap, this paper integrates for the first time environmental, economic and social aspects of shale gas to evaluate its overall sustainability. The focus is on the UK which is on the cusp of developing a shale gas industry. Shale gas is compared to other electricity options for the current situation and future scenarios up to the year 2030 to investigate whether it can contribute towards a more sustainable electricity mix in the UK. The results obtained through multi-criteria decision analysis suggest that, when equal importance is assumed for each of the three sustainability aspects shale gas ranks seventh out of nine electricity options, with wind and solar PV being the best and coal the worst options. However, it outranks biomass and hydropower. Changing the importance of the sustainability aspects widely, the ranking of shale gas ranges between fourth and eighth. For shale gas to become the most sustainable option of those assessed, large improvements would be needed, including a 329-fold reduction in environmental impacts and 16 times higher employment, along with simultaneous large changes (up to 10,000 times) in the importance assigned to each criterion. Similar changes would be needed if it were to be comparable to conventional or liquefied natural gas, biomass, nuclear or hydropower. The results also suggest that a future electricity mix (2030) would be more sustainable with a lower rather than a higher share of shale gas. These results serve to inform UK policy makers, industry and non-governmental organisations. They will also be of interest to other countries considering exploitation of shale gas

Atividade da reductase do nitrato em milho (Zea mays L.) var. Piranão em níveis crescentes de nitrogênio.

O objetivo deste trabalho foi estudar a atividade da reductase do nitrato em milho (Zea mays L. var. "Piranao") cultivado em solucao nutritiva e sob doses crescentes de nitrogenio, na forma de NO3. A atividade da enzima foi analisada aos 56 dias de idade, em rodelas de folhas do terco medio da folha +4, seguindo-se a metodologia proposta por MULDER et alii (15), adaptada por MALAVOLTA (13). Os resultados permitiram concluir que o aumento do teor de NO3 no meio favoreceu a atividade da reductase do nitrato ate o nivel maximo de 40,51 ug de N-NO-2/g de materia verde, correspondente a um nivel de 296,19 mg de N/litro de solucao nutritiva. Os resultados obtidos nas condicoes experimentais em que foi realizado o trabalho correspondem, provavelmente, ao maximo da capacidade genetica da variedade estudada. Os teores de N encontrados nas folhas inferiores foram mais baixos do que os das folhas superiores, em funcao da alta mobilizacao do elemento para as partes mais novas da planta. Houve tambem correlacao positiva entre a atividade da reductase do nitrato, o teor de N total da folha e a producao de materia seca

Biosynthesis of vitamin B12: the multi-enzyme synthesis of precorrin-4 and factor IV

AbstractBackground: In order to study the biosynthesis of vitamin B12, it is necessary to produce various intermediates along the biosynthetic pathway by enzymic methods. Recently, information on the organisation of the biosynthetic pathway has permitted the selection of the set of enzymes needed to biosynthesise any specific identified intermediate. The aim of the present work was to use recombinant enzymes in reconstituted multi-enzyme systems to biosynthesise particular intermediates.Results: The products of the cobG and cobJ genes from Pseudomonas denitrificans were expressed heterologously in Escherichia coli to afford good levels of activity of the corresponding enzymes, CobG and CobJ. Aerobic incubation of precorrin-3A with the CobG enzyme alone yielded precorrin-3B. When CobJ and S-adenosyl-l-methionine were included in the incubation, the product was precorrin-4. Both precorrin-3B and precorrin-4 are known precursors of vitamin B12 and their availability has allowed new mechanistic studies of enzymic transformations.Conclusions: Our results show that the expression of the CobG and CobJ enzymes has been successful, thus facilitating the biosynthesis of two precursors of vitamin B12. This lays the foundation for the structure determination of CobG and CobJ as well as future enzymic experiments focusing on later steps of vitamin B12 biosynthesis

Accuracy of Physical Self-Description Among Chronic Exercisers and Non-Exercisers

This study addressed the role of chronic exercise to enhance physical self-description as measured by self-estimated percent body fat. Accuracy of physical self-description was determined in normal-weight, regularly exercising and non-exercising males with similar body mass index (BMI)’s and females with similar BMI’s (n=42 males and 45 females of which 23 males and 23 females met criteria to be considered chronic exercisers). Statistical analyses were conducted to determine the degree of agreement between self-estimated percent body fat and actual laboratory measurements (hydrostatic weighing). Three statistical techniques were employed: Pearson correlation coefficients, Bland and Altman plots, and regression analysis. Agreement between measured and self-estimated percent body fat was superior for males and females who exercised chronically, compared to nonexercisers. The clinical implications are as follows. Satisfaction with one’s body can be influenced by several factors, including self-perceived body composition. Dissatisfaction can contribute to maladaptive and destructive weight management behaviors. The present study suggests that regular exercise provides a basis for more positive weight management behaviors by enhancing the accuracy of self-assessed body composition

A photometric mode identification method, including an improved non-adiabatic treatment of the atmosphere

We present an improved version of the method of photometric mode identification of Heynderickx et al. (1994). Our new version is based on the inclusion of precise non-adiabatic eigenfunctions determined in the outer stellar atmosphere according to the formalism recently proposed by Dupret et al.(2002). Our improved photometric mode identification technique is therefore no longer dependent on ad hoc parameters for the non-adiabatic effects. It contains the complete physical conditions of the outer atmosphere of the star, provided that rotation does not play a key role. We apply our improved method to the two slowly pulsating B stars HD 74560 and HD 138764 and to the beta Cephei star EN (16) Lac. Besides identifying the degree l of the pulsating stars, our method is also a tool for improving the knowledge of stellar interiors and atmospheres, by imposing constraints on parameters such as the metallicity and the mixing-length parameter alpha (a procedure we label non-adiabatic asteroseismology).Comment: 10 pages, 9 figures Accepted for publication in Astronomy and Astrophysic

Effect of convective outer layers modeling on non-adiabatic seismic observables of delta Scuti stars

The identification of pulsation modes in delta Scuti stars is mandatory to constrain the theoretical stellar models. The non-adiabatic observables used in the photometric identification methods depend, however,on convection modeling in the external layers. Our aim is to determine how the treatment of convection in the atmospheric and sub-atmospheric layers affects the mode identification, and what information about the thermal structure of the external layers can be obtained from amplitude ratios and phase lags in Str\"omgren photometric bands. We derive non-adiabatic parameters for delta Scuti stars by using, for the first time, stellar models with the same treatment of convection in the interior and in the atmosphere. We compute classical non-gray mixing length models, and as well non-gray ``Full Spectrum of Turbulence'' models. Furthermore, we compute the photometric amplitudes and phases of pulsation by using the colors and the limb-darkening coefficents as derived from the same atmosphere models used in the stellar modeling. We show that the non-adiabatic phase-lag is mainly sensitive to the thermal gradients in the external layers, (and hence to the treatment of convection), and that this sensitivity is also clearly reflected in the multi-color photometric phase differences.Comment: 14 pag. 19 figs. accepted for publication in Astronomy and Astrophysic

Marine plastics threaten giant Atlantic Marine Protected Areas.

There has been a recent shift in global perception of plastics in the environment, resulting in a call for greater action. Science and the popular media have highlighted plastic as an increasing stressor [1,2]. Efforts have been made to confer protected status to some remote locations, forming some of the world's largest Marine Protected Areas, including several UK overseas territories. We assessed plastic at these remote Atlantic Marine Protected Areas, surveying the shore, sea surface, water column and seabed, and found drastic changes from 2013-2018. Working from the RRS James Clark Ross at Ascension, St. Helena, Tristan da Cunha, Gough and the Falkland Islands (Figure 1A), we showed that marine debris on beaches has increased more than 10 fold in the past decade. Sea surface plastics have also increased, with in-water plastics occurring at densities of 0.1 items m-3; plastics on seabeds were observed at ≤ 0.01 items m-2. For the first time, beach densities of plastics at remote South Atlantic sites approached those at industrialised North Atlantic sites. This increase even occurs hundreds of meters down on seamounts. We also investigated plastic incidence in 2,243 animals (comprising 26 species) across remote South Atlantic oceanic food webs, ranging from plankton to seabirds. We found that plastics had been ingested by primary consumers (zooplankton) to top predators (seabirds) at high rates. These findings suggest that MPA status will not mitigate the threat of plastic proliferation to this rich, unique and threatened biodiversity