2,754 research outputs found
Roberto Gerhard’s Sound Compositions: A Historical-Philological Perspective. Archive, Process, Intent and reenactment
No full textThis research advances the current state of knowledge in the field of early tape music both empirically and methodologically. The purpose of this study is to evaluate the impact that the electronic medium exerted in the musical thinking of Roberto Gerhard, one of the most outspoken, prolific and influential composers in the Spanish diaspora whose musical legacy, for the most part unknown, is a major landmark in the early history of electroacoustic music. Gerhard’s personal tape collection, one of the largest historical archives of its kind reported in the literature, is exceptional for both its antiquity (50+-year-old tapes) and its abundance of production materials. Through the digitisation and analysis of the composer’s tape collection this research argues that the empirical study of audio documents sets out a basis for a broader understanding of textual processes. More specifically, the research demonstrates that the reconstruction of works based on magnetic tape sketches is a powerful method to advance the understanding of early tape music. This research also examines Gerhard’s sound compositions in relation to the post-war context in which they were composed. Finally, this research presents performance documentation that proposes an approach to the electroacoustic music repertoire in which creativity is not at odds with rigor and critical discernment demonstrating that archival study can be closely aligned to the concept of re-enactment
New diruthenium acetylide donor complexes for bulk-heterojunction solar cells
No full textConjugated polymers and oligomers have received a lot of attention as active materials for organic photovoltaic devices because of their potential for the development of plastic solar cells that are lightweight, flexible, and low cost. Bulk heterojunctions fabricated by blending polymers with fullerene derivative have resulted in great improvements in the polymer photovoltaic cell efficiencies.
The most commonly used materials are poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) [1], these cells with optimized device structure and fabbrication conditions can reach efficiencies in the range of 5-5.5%.
However, to produce highly efficient organic photovoltaic devices, it is necessary to extend the light absorption into the near-infrared region and at the same time preserve the high IPCE and open-circuit voltage.
Several papers have been recently dedicated to the investigation of the use of conjugated polymers incorporating heavy atoms; in particular Pt acetylide polymers as donors in solar cells using PCBM as acceptor [2] were proposed as a tool to enhance charge photogeneration. For instance, Mei et al. reported on a Pt acetylide-based polymer using a 2,1,3-benzothiadiazole (BTD) acceptor moiety flanked on either side by 2,5-thienyl (Th) donor units ([-Pt(L2)-t-Th-BTD-Th-t-]n, where L = PBu3), which absorbs strongly throughout the visible region. [3]
The use of Ru acetylides is a novel interesting tool for the design of donor materials [4] to combine with electron-withdrawing fullerides in bulk heterojunction solar cells.
New dinuclear Ru(II) complexes where two Ru atoms are separated by a bridge consisting of a 2,1,3 benzothiadiazole acceptor moiety flanked on either side by 2,5-thienyl or 3-hexyl substituted 2, 5 thienyl donor units were synthesized. (Figure 1)
These rather simple complexes appears to behave as a photoactive donor when blended with a fullerene as acceptor, thus being a first step toward novel bulk heterojunction solar cells, based on Ru donor systems
Figure 1
1. F. Padinger, R. S. Rittberger, N. S Sariciftci, Adv. Funct. Mater, 13 (2003) 85–88.
2. W.-Y. Wong, C.-L. Ho, Acc. Chem. Res. 43 (2010) 1246.
3. J.Mei, et al. Appl. Mater. Interfaces 1 (2009) 150.
4. A. Colombo, C. Dragonetti, D. Roberto, R. Ugo, L. Falciola, S. Luzzati, and D. Kotowski Organometallics (2011) doi: 10.1021om100846
Da solução ao problema: um estudo sobre os conflitos, os impactos sócio-ambientais e as representações sociais envolvidas no uso e na gestão da água do aquífero Karst no município de Colombo (PR)
Get PDFDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciencias Humanas. Programa de Pós-graduação em Sociologia PolíticaEsta dissertação trata das representações sociais dos sujeitos envolvidos no uso e na gestão da água do Aqüífero Karst no Município de Colombo (PR), desde o início da sua utilização, em 1995, até os dias atuais. A exploração deste aqüífero, que no seu início tratava-se de uma solução institucional para o problema da falta de água na área urbana de Colombo, tornou-se o cenário de conflitos e impactos sócio-ambientais. Sob a luz do modelo de análise das representações sociais e da gestão patrimonial dos recursos naturais, analisam-se os fatores comuns do conflito e do uso da água entre três categorias de sujeitos envolvidos no uso e gestão da água do Aqüífero Karst: Agricultores, Técnicos da Sanepar e Órgãos Públicos. A pesquisa apontou que o conflito se manifestara, de um lado, pelos agricultores que alegavam a exploração irracional do aqüífero interferindo diretamente na disponibilidade de água dos mesmos para a irrigação da agricultura; e do outro lado, pela Sanepar que alegava a impossibilidade de interromper a captação do aqüífero em função de ser a única solução viável para atender a demanda por água em Colombo. Os resultados da análise das representações sociais dos sujeitos envolvidos, tanto sobre o conflito como em relação aos significados do uso da água, apontaram uma vinculação entre as representações dos sujeitos com o papel social que os mesmos desenvolvem. Na categoria dos Agricultores, os resultados demonstraram que a água representa a manutenção tanto da sobrevivência física como da renda econômica familiar dos sujeitos, sendo causa motivadora do conflito. Na categoria dos Técnicos da Sanepar os resultados vincularam com uma das missões da empresa, o abastecimento público. E nos Órgãos Públicos, os resultados relacionaram-se com a missão social que os mesmos representam, como a gestão, fiscalização, licenciamento ambiental e mediação de conflitos sociais e ambientais. This thesis deals with the social representations of the subjects involved in the use and the management of the water on Karst Aquifer in the City of Colombo (PR), since the beginning of its use, in 1995, until the current days. The exploration of this aquifer, that in its beginning it was about an institutional solution for the problem of the water lack in the urban area of Colombo, became the partner-ambient scene of conflicts and impacts. It was used in this thesis the model of analysis of the social representations and the patrimonial management of the natural resources. One analyzed the common factors of the conflict and of the use of the water on three categories of involved citizens in the use and management of Karst Aquifer water: Farmers, Technicians of Sanepar Company and Public Agencies. The research indicated that the conflict expressed, on the one side, by the farmers claiming that the irrational exploitation of Karst Aquifer interfered directly on the availability of water from them for irrigation agriculture. The other side, by Sanepar claiming the impossibility of stops the capture of this Aquifer in line to be the only viable solution to meet the demand for water in Colombo City. The results of analysis of social representations of the subjects involved, as much on the conflict as in relation to the meanings of the use of the water, pointed a linkage between the representations of the subjects with the social role that they develop. In the category of farmers, the results showed that the water represents both maintenance of the physical survival as of the familiar economic income of the citizens, being the motivating factor of the conflict. In the category of Technicians of Sanepar Company, the results linked with one of the missions of the company, the supply public. And in the Public Agencies, the results related with the social mission that they represent, as the management, supervision, licensing and environmental mediation of social conflicts and environmental
Indicators of ozone effects on Fagus sylvatica L
No full textIn this paper optical indices calculated from leaf reflectance measurements, acquired with a high resolution spectroradiometer, were investigated to monitor 03 stress on Fagus sylvatica L. from the strain phase to the damage phase when visible symptoms occur (e.g. chlorosis, leaf browning). The CI (Chlorophyll Index) was the most sensible index to a wide range of chlorophyll (Chl) concentrations (R(2)=0.93), the simple ratio R(695)/R(740) (Ctr2) was the most correlated to carotenoids/chlorophyll (Car/Chl) ratio (R(2)=0.65), while Yl (Yellowness Index) was sensible to Car/Chl ratio and to low Chl values but tends to saturate at moderate to high Chl concentrations. PRI (Photochemical Reflectance Index) was correlated with the physiological parameters NPQ (Non Photochemical Quenching) and Delta F/F(m)' confirming this index is a good indicator of photosynthetic efficiency.
Results from this experiment showed that Cl, Ctr2 and PRI were reliable indices of 03 effects on Fagus sylvatica L. before visible symptoms occurred, while Yl was able to detect the senescence anticipation when visible symptoms already spread. These results were confirmed by physiological parameters measured in field (F(v)/F(m), NPQ and Delta F/F(m)')
Long-term orbital propagation through differential algebra transfer maps and averaging semi-analytical approaches
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A New Dynamometric Technique to Measure and Locate Endocranial Structures. Preliminary Report
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La raccolta di capitale di rischio nei gruppi industriali italiani e la separazione tra possesso e controllo
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