Critérios e indicadores para avaliação da sustentabilidade de empresa florestal em Tailândia, Pará, na Amazônia brasileira.

O objetivo deste trabalho foi gerar fundamentos de um grupo de critérios e indicadores (C&I) adequados para serem utilizados em monitoramento empresarial e em auditagem de sustentabilidade das atividades de indústria madeireira na Amazônia oriental brasileira. O estudo se baseia na suposição de que C&I práticos e viáveis dependem das considerações dos interesses, visões e valores dos principais grupos de atores envolvidos no sistema de uso florestal. A ideia central do estudo foi identificar diferenças entre quatro grupos de atores (atores locais, governo, grupo operacional e pesquisadores) na avaliação de um conjunto de C&I definidos por pesquisadores internacionais em um Workshop, e usar as diferenças detectadas para elaborar, em forma participativa, os critérios adequados para monitoramento e auditagem. Um elemento metodológico importante foi a avaliação da sustentabilidade das atividades de uma empresa florestal pela aplicação pratica de C&I. O estudo confirmou o grande potencial desses critérios para avaliação da sustentabilidade das atividades de avaliação entre os diversos grupos. Pode-se afirmar que para os usuários potenciais, a praticidade e a simplicidade dos C&I são muito importantes, como também a relação entre custos e benefícios da aplicação dos mesmos. Conclui-se que o resultado da avaliação da sustentabilidade através dos C&I depende muito dos métodos utilizados para levantar informações. Para facilitar a aplicação de C&I em ferramentas de monitoramento e auditagem, os esforços futuros devem dimensionar-se na busca de verificadores inquestionáveis, de métodos de avaliação e definição de recomendações especificas introduzidas de resultados de avaliação.bitstream/item/63186/1/Oriental-Doc34.pd

Collisional shifts in optical-lattice atom clocks

We theoretically study the effects of elastic collisions on the determination of frequency standards via Ramsey fringe spectroscopy in optical-lattice atom clocks. Interparticle interactions of bosonic atoms in multiply-occupied lattice sites can cause a linear frequency shift, as well as generate asymmetric Ramsey fringe patterns and reduce fringe visibility due to interparticle entanglement. We propose a method of reducing these collisional effects in an optical lattice by introducing a phase difference of $\pi$ between the Ramsey driving fields in adjacent sites. This configuration suppresses site to site hopping due to interference of two tunneling pathways, without degrading fringe visibility. Consequently, the probability of double occupancy is reduced, leading to cancellation of collisional shifts.Comment: 15 pages, 11 figure

Spectrally efficient transmit diversity scheme for differentially modulated multicarrier transmissions

Cyclic delay diversity is a simple, yet effective, transmit diversity scheme for multicarrier based transmissions employing coherent digital linear modulation schemes. It is shown that, for satisfactory operation, the scheme requires additional channel estimation overhead compared to single antenna and traditional space–time coded transmissions owing to the inherent increase in frequency selective fading. The authors analyse the additional channel estimation overhead requirement for a Hiperlan #2 style system with two transmit antennas operating in a NLOS indoor environment. The analysis shows that an additional overhead of 500% is required for the candidate system compared to a single antenna system. It is also shown that by employing differential modulation the channel estimation overhead can be eliminated with significant performance improvement compared to a system employing a practical channel estimation scheme. This novel combination, termed ‘differentially modulated cyclic delay diversity, is shown to yield a highly spectral efficient, yet simple transmit diversity solution for multi-carrier transmissions

Stratification-induced variations in nutrient utilization in the Polar North Atlantic during past interglacials

Vertical water mass structure in the Polar North Atlantic Ocean plays a critical role in planetary climate by influencing the formation rate of North Atlantic deepwater, which in turn affects surface heat transfer in the northern hemisphere, ventilation of the deep sea, and ocean circulation on a global scale. However, the response of upper stratification in the Nordic seas to near-future hydrologic forcing, as surface water warms and freshens due to global temperature rise and Greenland ice demise, remains poorly known. While past major interglacials are viewed as potential analogues of the present, recent findings suggest that very different surface ocean conditions prevailed in the Polar North Atlantic during Marine Isotope Stage (MIS) 5e and 11 compared to the Holocene. It is thus crucial to identify the causes of those differences in order to understand their role in climatic and oceanographic variability. To resolve this, we pair here bulk sediment 15N isotopic signatures with planktonic foraminiferal assemblages and their isotopic composition across major past interglacials. The comparison defines for the first time stratification-induced variations in nitrate utilization up to 25% between and within all of these warm periods that highlight changes in the thickness of the mixed-layer throughout the previous interglacials. That thickness directly controls the depth-level of Atlantic water inflow. The major changes of nitrate utilization recorded here thus suggest that a thicker mixed-layer prevailed during past interglacials, probably related to longer freshwater input associated with the preceding glacial termination. This would have caused the Atlantic water to flow at greater depth during MIS 5e and 11. These results call for caution when using older interglacials as modern or near-future climate analogues and contribute to the improvement of our general comprehension of the impact of freshwater input near a globally important deep-water formation site like the Nordic Seas. This is crucial when assessing the negative impacts on the Greenland Ice Sheet of climate change and global warming.published_or_final_versio

Towards a comprehensive open source platform for management and analysis of High Content Screening data

As High Content Screening (HCS) has moved into the main stream for biological and pharmaceutical investigations, a lag of well integrated pipelines for automated acquisition, management and analysis of HCS results turns out to be a bottleneck for fully leveraging the wealth of information contained in a screen and moving to higher throughput. For many applications, monolithic pipelines can not deliver the flexibility and versatility needed. Laboratories and scientific service providers instead usually look into integrating components from both, the open source world and the commercial software world into best-of-breed data pipelines. In this article, we will present two open source components that can be used as flexible and powerful building blocks for such a pipeline

Photoemission induced gating of topological insulator

The recently discovered topological insulators exhibit topologically protected metallic surface states which are interesting from the fundamental point of view and could be useful for various applications if an appropriate electronic gating can be realized. Our photoemission study of Cu intercalated Bi2Se3 shows that the surface states occupancy in this material can be tuned by changing the photon energy and understood as a photoemission induced gating effect. Our finding provides an effective tool to investigate the new physics coming from the topological surface states and suggests the intercalation as a recipe for synthesis of the material suitable for electronic applications.Comment: + resistivity data and some discussio

Adaptability of the fine root system of Ceiba pentandra (L.) Gaertn. to various sites of central Amazônia, Brazil

Ceiba pentandra (L.) Gaertn. (sumaúma), an economically important tree species in central Amazônia, stands out on account of its considerable ecological capacity of adapting to different site conditions. It can survive under seasonally dry conditions on terra firme as well as in the seasonally inundated várzea. Particularly the fine roots can structurally adapt to different soil conditions. The adaptation of the fine roots to terra firme condition results in the formation of an aerenchyma consisting of only small intercellular canals. During the dry months the walls of the epidermis cells increase in thickness and moreover they lignify and the exodermis suberize to prevent drainage. On the other hand the fine roots growing on várzea sites form lysigenously an aerenchyma consisting of extended and large intercellulars both within the cortex and the central cylinder. This large intercellular system supplies the plant with water and mineral elements and maintains the oxygen supply enabling photosynthesis throughout the year. In addition, above the soil surface numerous adventitious roots grow during the inundation period developing only small intercellular spaces within the cortex. Suberization is missing and only the primary xylem lignifies.A simulation of the fine root study under similar growth conditions in a tropical greenhouse completely confirmed the structural adaptations of the fine roots to dry and seasonally inundated conditions. This ecological amplitude is important for the selection of Ceiba pentandra for sustainably managed forestry systems

Adaptability of the fine root system of Ceiba pentandra (L.) Gaertn. to various sites of central Amazônia, Brazil.

The objective of the following study of this commercially important species was to find out in how far dynamic adaptation of the growth and structure of the fine roots can contribute to that outstanding ecological amplitude. The structural study of the fine roots from trees from terra firme and várzea in different seasons in combination with a simulation of drought and inundation conditions in the greenhouse with young plants were expected to help explain the species extensive ecological amplitude