Para lá da técnica: delimitar fronteiras entre componentes indissociáveis da execução instrumental

O termo “técnica” tem sido usado, ao longo dos tempos, com diferentes significados e em contextos vários, entre os quais o da execução musical instrumental. Ao observar a diversidade de acepções já atribuídas ao vocábulo no campo da performance de obras musicais instrumentais, apercebemo-nos da falta de consenso que persiste quanto (1) à compreensão do seu significado neste contexto particular; (2) à identificação das componentes da execução instrumental que excedem os limites da técnica. O presente texto pretende sugerir possibilidades de resposta a estas duas questões, sem ambicionar explorá-las exaustivamente. É ilustrado com referências a alguns dos inúmeros autores que, no passado, se debruçaram sobre a questão da técnica e sobre outras com esta relacionadas, pretendendo incorporar algumas das suas ideias numa perspectiva pessoal do autor

Online fatigue crack growth monitoring with clip gauge and direct current potential drop

Fatigue is a well-known failure phenomenon which has been and still is extensively studied. Often structures are designed according to the safe-life principle so no crack initiation occurs. Nowadays there is a high emphasis on cost-efficiency, and one might rather opt for a fail-safe design. Therefore a certain amount of crack growth can be allowed in structures, but then a good knowledge of stresses and related crack growth rates is needed. To this end, extensive studies are done to obtain a material’s Paris law curve. Within the framework of research for offshore wind turbine constructions, tests were done to determine the crack growth rate of a high strength low alloy (HSLA) steel. A dedicated LabVIEW program was developed to be able to determine an entire Paris law curve with a single specimen, by controlling the stress intensity factor range (ΔK). The program is controlled by the readings of a clip gauge, which make it possible to plan the amount of crack growth per ΔK block and thus plan an entire test in advance. The potential drop technique was also applied in order to obtain the Paris law curve. Clip gauge results were compared with direct current potential drop monitoring. This comparison was done by means of an a/W-N diagram and the resulting Paris law curves. The results show a very good correlation between both methods and with the visual confirmation

Reumaliin: inimeste reumatoloogiaalane nõustamine ja selle rakendamise kogemus

Meditsiinialane telefoninõustamine on inimestele vajalik ja huvipakkuv teenus. TÜ Kliinikumi sisekliinikus käivitus 2001. aastal projekt “Reumaliin” kogu Eesti rahva reumatoloogiaalaseks nõustamiseks. Selle projekti esimese tööaasta kogemused näitavad, et telefoninõustamine vähendab ambulatoorsete visiitide hulka, aitab kokku hoida spetsialisti tööaega ning on patsiendile kiireks ja efektiivseks võimaluseks saada oma probleemidele lahendus juhtudel, kui ei ole vaja spetsiifilist reumatoloogiaalast konsultatsiooni. Reumaliini töökogemus tõi esile telefoninõustamise raamjuhiste väljatöötamise vajalikkuse tulevikus. Eesti Arst 2002; 81 (11): 718–72

Tapping into the maize root microbiome to identify bacteria that promote growth under chilling conditions

Background When maize (Zea mays L.) is grown in the Northern hemisphere, its development is heavily arrested by chilling temperatures, especially at the juvenile phase. As some endophytes are beneficial for plants under stress conditions, we analyzed the impact of chilling temperatures on the root microbiome and examined whether microbiome-based analysis might help to identify bacterial strains that could promote growth under these temperatures. Results We investigated how the maize root microbiome composition changed by means of 16S rRNA gene amplicon sequencing when maize was grown at chilling temperatures in comparison to ambient temperatures by repeatedly cultivating maize in field soil. We identified 12 abundant and enriched bacterial families that colonize maize roots, consisting of bacteria recruited from the soil, whereas seed-derived endophytes were lowly represented. Chilling temperatures modified the root microbiome composition only slightly, but significantly. An enrichment of several chilling-responsive families was detected, of which the Comamonadaceae and the Pseudomonadaceae were the most abundant in the root endosphere of maize grown under chilling conditions, whereas only three were strongly depleted, among which the Streptomycetaceae. Additionally, a collection of bacterial strains isolated from maize roots was established and a selection was screened for growth-promoting effects on juvenile maize grown under chilling temperatures. Two promising strains that promoted maize growth under chilling conditions were identified that belonged to the root endophytic bacterial families, from which the relative abundance remained unchanged by variations in the growth temperature. Conclusions Our analyses indicate that chilling temperatures affect the bacterial community composition within the maize root endosphere. We further identified two bacterial strains that boost maize growth under chilling conditions. Their identity revealed that analyzing the chilling-responsive families did not help for their identification. As both strains belong to root endosphere enriched families, visualizing and comparing the bacterial diversity in these communities might still help to identify new PGPR strains. Additionally, a strain does not necessarely need to belong to a high abundant family in the root endosphere to provoke a growth-promoting effect in chilling conditions

Metaproteomic evidence of changes in protein expression following a change in electrode potential in a robust biocathode microbiome

Microorganisms that respire electrodes may be exploited for biotechnology applications if key pathways for extracellular electron transfer (EET) can be identified and manipulated through bioengineering. To determine whether expression of proposed Biocathode-MCL EET proteins are changed by modulating electrode potential without disrupting the relative distribution of microbial constituents, metaproteomic and 16S rRNA gene expression analyses were performed after switching from an optimal to suboptimal potential based on an expected decrease in electrode respiration. Five hundred and seventy-nine unique proteins were identified across both potentials, the majority of which were assigned to three previously defined Biocathode-MCL metagenomic clusters: a Marinobacter sp., a member of the family Chromatiaceae, and a Labrenzia sp. Statistical analysis of spectral counts using the Fisher's exact test identified 16 proteins associated with the optimal potential, five of which are predicted electron transfer proteins. The majority of proteins associated with the suboptimal potential were involved in protein turnover/turnover, motility, and membrane transport. Unipept and 16S rRNA gene expression analyses indicated that the taxonomic profile of the microbiome did not change after 52 hours at the suboptimal potential. These findings show that protein expression is sensitive to the electrode potential without inducing shifts in community composition, a feature that may be exploited for engineering Biocathode-MCL

Geobacter, Anaeromyxobacter and Anaerolineae populations are enriched on anodes of root exudate-driven microbial fuel cells in rice field soil

Plant-based sediment microbial fuel cells (PMFCs) couple the oxidation of root exudates in living rice plants to current production. We analysed the composition of the microbial community on anodes from PMFC with natural rice field soil as substratum for rice by analysing 16S rRNA as an indicator of microbial activity and diversity. Terminal restriction fragment length polymorphism (TRFLP) analysis indicated that the active bacterial community on anodes from PMFCs differed strongly compared with controls. Moreover, clones related to Deltaproteobacteria and Chloroflexi were highly abundant (49% and 21%, respectively) on PMFCs anodes. Geobacter (19%), Anaeromyxobacter (15%) and Anaerolineae (17%) populations were predominant on anodes with natural rice field soil and differed strongly from those previously detected with potting soil. In open circuit (OC) control PMFCs, not allowing electron transfer, Deltaproteobacteria (33%), Betaproteobacteria (20%), Chloroflexi (12%), Alphaproteobacteria (10%) and Firmicutes (10%) were detected. The presence of an electron accepting anode also had a strong influence on methanogenic archaea. Hydrogenotrophic methanogens were more active on PMFC (21%) than on OC controls (10%), whereas acetoclastic Methanosaetaceae were more active on OC controls (31%) compared with PMFCs (9%). In conclusion, electron accepting anodes and rice root exudates selected for distinct potential anode-reducing microbial populations in rice soil inoculated PMFC

A Previously Uncharacterized, Nonphotosynthetic Member of the Chromatiaceae Is the Primary CO_2-Fixing Constituent in a Self-Regenerating Biocathode

Biocathode extracellular electron transfer (EET) may be exploited for biotechnology applications, including microbially mediated O_2 reduction in microbial fuel cells and microbial electrosynthesis. However, biocathode mechanistic studies needed to improve or engineer functionality have been limited to a few select species that form sparse, homogeneous biofilms characterized by little or no growth. Attempts to cultivate isolates from biocathode environmental enrichments often fail due to a lack of some advantage provided by life in a consortium, highlighting the need to study and understand biocathode consortia in situ. Here, we present metagenomic and metaproteomic characterization of a previously described biocathode biofilm (+310 mV versus a standard hydrogen electrode [SHE]) enriched from seawater, reducing O_2, and presumably fixing CO_2 for biomass generation. Metagenomics identified 16 distinct cluster genomes, 15 of which could be assigned at the family or genus level and whose abundance was roughly divided between Alpha- and Gammaproteobacteria. A total of 644 proteins were identified from shotgun metaproteomics and have been deposited in the the ProteomeXchange with identifier PXD001045. Cluster genomes were used to assign the taxonomic identities of 599 proteins, with Marinobacter, Chromatiaceae, and Labrenzia the most represented. RubisCO and phosphoribulokinase, along with 9 other Calvin-Benson-Bassham cycle proteins, were identified from Chromatiaceae. In addition, proteins similar to those predicted for iron oxidation pathways of known iron-oxidizing bacteria were observed for Chromatiaceae. These findings represent the first description of putative EET and CO_2 fixation mechanisms for a self-regenerating, self-sustaining multispecies biocathode, providing potential targets for functional engineering, as well as new insights into biocathode EET pathways using proteomics