917 resultados para Recent past
Resumo:
Biodiesel production has received considerable attention in the recent past as a nonpolluting fuel. However, this assertion has been based on its biodegradability and reduction in exhaust emissions. Assessments of water and soil biodiesel pollution are still limited. Spill simulation with biodiesel and their diesel blends in soils were carried out, aiming at analyzing their cytotoxic and genotoxic potentials. While the cytotoxicity observed may be related to diesel contaminants, the genotoxic and mutagenic effects can be ascribed to biodiesel pollutants. Thus, taking into account that our data stressed harmful effects on organisms exposed to biodiesel-polluted soils, the designation of this biofuel as an environmental-friendly fuel should be carefully reviewed to assure environmental quality. (C) 2011 Elsevier B.V. All rights reserved.
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Biological processes are very complex mechanisms, most of them being accompanied by or manifested as signals that reflect their essential characteristics and qualities. The development of diagnostic techniques based on signal and image acquisition from the human body is commonly retained as one of the propelling factors in the advancements in medicine and biosciences recorded in the recent past. It is a fact that the instruments used for biological signal and image recording, like any other acquisition system, are affected by non-idealities which, by different degrees, negatively impact on the accuracy of the recording. This work discusses how it is possible to attenuate, and ideally to remove, these effects, with a particular attention toward ultrasound imaging and extracellular recordings. Original algorithms developed during the Ph.D. research activity will be examined and compared to ones in literature tackling the same problems; results will be drawn on the base of comparative tests on both synthetic and in-vivo acquisitions, evaluating standard metrics in the respective field of application. All the developed algorithms share an adaptive approach to signal analysis, meaning that their behavior is not dependent only on designer choices, but driven by input signal characteristics too. Performance comparisons following the state of the art concerning image quality assessment, contrast gain estimation and resolution gain quantification as well as visual inspection highlighted very good results featured by the proposed ultrasound image deconvolution and restoring algorithms: axial resolution up to 5 times better than algorithms in literature are possible. Concerning extracellular recordings, the results of the proposed denoising technique compared to other signal processing algorithms pointed out an improvement of the state of the art of almost 4 dB.
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The present study aims at assessing the innovation strategies adopted within a regional economic system, the Italian region Emilia-Romagna, as it faced the challenges of a changing international scenario. As the strengthening of the regional innovative capabilities is regarded as a keystone to foster a new phase of economic growth, it is important also to understand how the local industrial, institutional, and academic actors have tackled the problem of innovation in the recent past. In this study we explore the approaches to innovation and the strategies adopted by the main regional actors through three different case studies. Chapter 1 provides a general survey of the innovative performance of the regional industries over the past two decades, as it emerges from statistical data and systematic comparisons at the national and European levels. The chapter also discusses the innovation policies that the regional government set up since 2001 in order to strengthen the collaboration among local economic actors, including universities and research centres. As mechanics is the most important regional industry, chapter 2 analyses the combination of knowledge and practices utilized in the period 1960s-1990s in the design of a particular kind of machinery produced by G.D S.p.A., a world-leader in the market of tobacco packaging machines. G.D is based in Bologna, the region’s capital, and is at the centre of the most important Italian packaging district. In chapter 3 the attention turns to the institutional level, focusing on how the local public administrations, and the local, publicly-owned utility companies have dealt with the creation of new telematic networks on the regional territory during the 1990s and 2000s. Finally, chapter 4 assesses the technology transfer carried out by the main university of the region – the University of Bologna – by focusing on the patenting activities involving its research personnel in the period 1960-2010.
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The treatment of multiple myeloma has undergone significant changes in the recent past. The arrival of novel agents, especially thalidomide, bortezomib and lenalidomide, has expanded treatment options and patient outcomes are improving significantly. This article summarises the discussions of an expert meeting which was held to debate current treatment practices for multiple myeloma in Switzerland concerning the role of the novel agents and to provide recommendations for their use in different treatment stages based on currently available clinical data. Novel agent combinations for the treatment of newly diagnosed, as well as relapsed multiple myeloma are examined. In addition, the role of novel agents in patients with cytogenetic abnormalities and renal impairment, as well as the management of the most frequent side effects of the novel agents are discussed. The aim of this article is to assist in treatment decisions in daily clinical practice to achieve the best possible outcome for patients with multiple myeloma.
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Biological diversity and its constituent chemical diversity have served as one of the richest sources of bioprospecting leading to the discovery of some of the most important bioactive molecules for mankind. Despite this excellent record, in the recent past, however, bioprospecting of biological resources has met with little success; there has been a perceptible decline in the discovery of novel bioactive compounds. Several arguments have been proposed to explain the current poor success in bioprospecting. Among them, it has been argued that to bioprospect more biodiversity may not necessarily be productive, considering that chemical and functional diversity might not scale with biological diversity. In this paper, we offer a critique on the current perception of biodiversity and chemodiversity and ask to what extent it is relevant in the context of bioprospecting. First, using simple models, we analyze the relation among biodiversity, chemodiversity and functional redundancies in chemical plans of plants and argue that the biological space for exploration might still be wide open. Second, in the context of future bioprospecting, we argue that brute-force high throughput screening approaches alone are insufficient and cost ineffective in realizing bioprospecting success. Therefore, intelligent or non-random approaches to bioprospecting need to be adopted. We review here few examples of such approaches and show how these could be further developed and used in the future to accelerate the pace of discovery.
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[1] Winter circulation types under preindustrial and glacial conditions are investigated and used to quantify their impact on precipitation. The analysis is based on daily mean sea level pressure fields of a highly resolved atmospheric general circulation model and focuses on the North Atlantic and European region. We find that glacial circulation types are dominated by patterns with an east-west pressure gradient, which clearly differs from the predominantly zonal patterns for the recent past. This is also evident in the frequency of occurrence of circulation types when projecting preindustrial circulation types onto the glacial simulations. The elevation of the Laurentide ice sheet is identified as a major cause for these differences. In areas of strong precipitation signals in glacial times, the changes in the frequencies of occurrence of the circulation types explain up to 60% of the total difference between preindustrial and glacial simulations.
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Wind power based generation has been rapidly growing world-wide during the recent past. In order to transmit large amounts of wind power over long distances, system planners may often add series compensation to existing transmission lines owing to several benefits such as improved steady-state power transfer limit, improved transient stability, and efficient utilization of transmission infrastructure. Application of series capacitors has posed resonant interaction concerns such as through subsynchronous resonance (SSR) with conventional turbine-generators. Wind turbine-generators may also be susceptible to such resonant interactions. However, not much information is available in literature and even engineering standards are yet to address these issues. The motivation problem for this research is based on an actual system switching event that resulted in undamped oscillations in a 345-kV series-compensated, typical ring-bus power system configuration. Based on time-domain ATP (Alternative Transients Program) modeling, simulations and analysis of system event records, the occurrence of subsynchronous interactions within the existing 345-kV series-compensated power system has been investigated. Effects of various small-signal and large-signal power system disturbances with both identical and non-identical wind turbine parameters (such as with a statistical-spread) has been evaluated. Effect of parameter variations on subsynchronous oscillations has been quantified using 3D-DFT plots and the oscillations have been identified as due to electrical self-excitation effects, rather than torsional interaction. Further, the generator no-load reactance and the rotor-side converter inner-loop controller gains have been identified as bearing maximum sensitivity to either damping or exacerbating the self-excited oscillations. A higher-order spectral analysis method based on modified Prony estimation has been successfully applied to the field records identifying dominant 9.79 Hz subsynchronous oscillations. Recommendations have been made for exploring countermeasures.
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A distinguishing feature of the discipline of archaeology is its reliance upon sensory dependant investigation. As perceived by all of the senses, the felt environment is a unique area of archaeological knowledge. It is generally accepted that the emergence of industrial processes in the recent past has been accompanied by unprecedented sonic extremes. The work of environmental historians has provided ample evidence that the introduction of much of this unwanted sound, or "noise" was an area of contestation. More recent research in the history of sound has called for more nuanced distinctions than the noisy/quiet dichotomy. Acoustic archaeology tends to focus upon a reconstruction of sound producing instruments and spaces with a primary goal of ascertaining intentionality. Most archaeoacoustic research is focused on learning more about the sonic world of people within prehistoric timeframes while some research has been done on historic sites. In this thesis, by way of a meditation on industrial sound and the physical remains of the Quincy Mining Company blacksmith shop (Hancock, MI) in particular, I argue for an acceptance and inclusion of sound as artifact in and of itself. I am introducing the concept of an individual sound-form, or sonifact, as a reproducible, repeatable, representable physical entity, created by tangible, perhaps even visible, host-artifacts. A sonifact is a sound that endures through time, with negligible variability. Through the piecing together of historical and archaeological evidence, in this thesis I present a plausible sonifactual assemblage at the blacksmith shop in April 1916 as it may have been experienced by an individual traversing the vicinity on foot: an 'historic soundwalk.' The sensory apprehension of abandoned industrial sites is multi-faceted. In this thesis I hope to make the case for an acceptance of sound as a primary heritage value when thinking about the industrial past, and also for an increased awareness and acceptance of sound and listening as a primary mode of perception.
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Novel leads are urgently required for designing antimalarials due to the reduced efficacy of presently available drugs. The malaria parasite has a unique reaction of heme polymerization, which has attracted much attention in the recent past as a target for the design of antimalarial drugs. The process is hampered by non-availability of a proper assay method. Currently available methods are cumbersome and require advanced instrumentation or radioactive substrates. Here, we are describing an assay for hemozoin formation that is simple and reproducible. This assay has routinely been used by us for the identification of potential compounds with antimalarial activity.
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Whether interspecific hybridization is important as a mechanism that generates biological diversity is a matter of controversy. Whereas some authors focus on the potential of hybridization as a source of genetic variation, functional novelty and new species, others argue against any important role, because reduced fitness would typically render hybrids an evolutionary dead end. By drawing on recent developments in the genetics and ecology of hybridization and on principles of ecological speciation theory, I develop a concept that reconciles these views and adds a new twist to this debate. Because hybridization is common when populations invade new environments and potentially elevates rates of response to selection, it predisposes colonizing populations to rapid adaptive diversification under disruptive or divergent selection. I discuss predictions and suggest tests of this hybrid swarm theory of adaptive radiation and review published molecular phylogenies of adaptive radiations in light of the theory. Some of the confusion about the role of hybridization in evolutionary diversification stems from the contradiction between a perceived necessity for cessation of gene flow to enable adaptive population differentiation on the one hand [1], and the potential of hybridization for generating adaptive variation, functional novelty and new species 2, 3 and 4 on the other. Much progress in the genetics 5, 6, 7, 8 and 9 and ecology of hybridization 9, 10 and 11, and in our understanding of the role of ecology in speciation (see Glossary) 12, 13 and 14 make a re-evaluation timely. Whereas botanists traditionally stressed the diversity-generating potential of hybridization 2, 3 and 14, zoologists traditionally saw it as a process that limits diversification [1] and refer to it mainly in the contexts of hybrid zones (Box 1) and reinforcement of reproductive isolation [15]. Judging by the wide distribution of allopolyploidy among plants, many plant species might be of direct hybrid origin or descended from a hybrid species in the recent past [16]. The ability to reproduce asexually might explain why allopolyploid hybrid species are more common in plants than in animals. Allopolyploidy arises when meiotic mismatch of parental chromosomes or karyotypes causes hybrid sterility. Mitotic error, duplicating the karyotype, can restore an asexually maintained hybrid line to fertility. Although bisexual allopolyploid hybrid species are not uncommon in fish [17] and frogs [18], the difficulty with which allopolyploid animals reproduce, typically requiring gynogenesis[19], makes establishment and survival of allopolyploid animal species difficult.
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The reliability of millimeter and sub-millimeter wave radiometer measurements is dependent on the accuracy of the loads they employ as calibration targets. In the recent past on-board calibration loads have been developed for a variety of satellite remote sensing instruments. Unfortunately some of these have suffered from calibration inaccuracies which had poor thermal performance of the calibration target as the root cause. Stringent performance parameters of the calibration target such as low reflectivity, high temperature uniformity, low mass and low power consumption combined with low volumetric requirements remain a challenge for the space instrument developer. In this paper we present a novel multi-layer absorber concept for a calibration load which offers an excellent compromise between very good radiometric performance and temperature uniformity and the mass and volumetric constraints required by space-borne calibration targets.
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Which forms of nitrogen (N) do plants acquire from soil? This question, central to understanding of plant function, was debated intensely a century ago. It was revitalized more recently with insights in plant–soil interactions and molecular biology, but the difficulties associated with dissecting rhizosphere processes – rapid absorption, uptake, conversion and release of N in the interfaces of soil, microbes and plants – have prevented resolution. In the recent past, inorganic redox reactions were discussed, while today's focus is transformations of organic N. Despite significant advances and relevance, views are diverging on the importance of organic N as a nutrient source for plants. A recent workshop brought together leading experts, early stage researchers and industry representatives to discuss and evaluate the current knowledge and on-going research to link from molecular function of plants to ecosystem processes.
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Comparisons of climate model hindcasts with independent proxy data are essential for assessing model performance in non-analogue situations. However, standardized palaeoclimate data sets for assessing the spatial pattern of past climatic change across continents are lacking for some of the most dynamic episodes of Earth’s recent past. Here we present a new chironomid-based palaeotemperature dataset designed to assess climate model hindcasts of regional summer temperature change in Europe during the late-glacial and early Holocene. Latitudinal and longitudinal patterns of inferred temperature change are in excellent agreement with simulations by the ECHAM-4 model, implying that atmospheric general circulation models like ECHAM-4 can successfully predict regionally diverging temperature trends in Europe, even when conditions differ significantly from present. However, ECHAM-4 infers larger amplitudes of change and higher temperatures during warm phases than our palaeotemperature estimates, suggesting that this and similar models may overestimate past and potentially also future summer temperature changes in Europe.
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In the recent past, various intrinsic connectivity networks (ICN) have been identified in the resting brain. It has been hypothesized that the fronto-parietal ICN is involved in attentional processes. Evidence for this claim stems from task-related activation studies that show a joint activation of the implicated brain regions during tasks that require sustained attention. In this study, we used functional magnetic resonance imaging (fMRI) to demonstrate that functional connectivity within the fronto-parietal network at rest directly relates to attention. We applied graph theory to functional connectivity data from multiple regions of interest and tested for associations with behavioral measures of attention as provided by the attentional network test (ANT), which we acquired in a separate session outside the MRI environment. We found robust statistical associations with centrality measures of global and local connectivity of nodes within the network with the alerting and executive control subfunctions of attention. The results provide further evidence for the functional significance of ICN and the hypothesized role of the fronto-parietal attention network. Hum Brain Mapp , 2013. © 2013 Wiley Periodicals, Inc.
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The consistency of an existing reconstructed annual (December–November) temperature series for the Lisbon region (Portugal) from 1600 onwards, based on a European-wide reconstruction, with (1) five local borehole temperature–depth profiles; (2) synthetic temperature– depth profiles, generated from both reconstructed temperatures and two regional paleoclimate simulations in Portugal; (3) instrumental data sources over the twentieth century; and (4) temperature indices from documentary sources during the late Maunder Minimum (1675–1715) is assessed. The low-frequency variability in the reconstructed temperature in Portugal is not entirely consistent with local borehole temperature–depth profiles and with the simulated response of temperature in two regional paleoclimate simulations driven by reconstructions of various climate forcings. Therefore, the existing reconstructed series is calibrated by adjusting its low-frequency variability to the simulations (first-stage adjustment). The annual reconstructed series is then calibrated in its location and scale parameters, using the instrumental series and a linear regression between them (second-stage adjustment). This calibrated series shows clear footprints of the Maunder and Dalton minima, commonly related to changes in solar activity and explosive volcanic eruptions, and a strong recent-past warming, commonly related to human-driven forcing. Lastly, it is also in overall agreement with annual temperature indices over the late Maunder Minimum in Portugal. The series resulting from this post-reconstruction adjustment can be of foremost relevance to improve the current understanding of the driving mechanisms of climate variability in Portugal.