Para este estudo foram utilizadas 30 coroas de dentes decíduos e 16 diferentes resinas compostas de diversas marcas comerciais. O objetivo foi comparar, in vitro, com o uso do espectrofotômetro, a diferença de unidades de cor (DE) de dentes decíduos e resinas compostas e, também, selecionar, in vitro, através de análise visual de três examinadores, as resinas compostas cujas cores mais se assemelhavam à cor dos dentes, utilizando as mesmas amostras do item anterior. Os resultados apontaram que apenas as resinas Herculite cor B1, Durafill cor SL e Filtek A110 cor B0,5 apresentaram DE menor ou igual a 3,5, demonstrando o restrito número de opções para uso em odontopediatria. Houve uma grande variação de tonalidades das resinas dentro da mesma designação de cor em diferentes marcas comerciais, o que indica a dificuldade do uso da escala de cor. A análise estatística mostrou haver diferença estatisticamente significante na comparação dos DE entre as diferentes resinas, (P £ 0,05). Na análise visual, os três examinadores consideraram a resina Durafill, cor SL, como a resina que mais se aproximou à cor dos dentes, seguida da Filltek Z250, cor B0,5 para os examinadores 1 e 3, e Filtek A110 cor B0,5 para o examinador 2. Na comparação realizada entre os resultados do espectrofotômetro com os examinadores para indicação da resina mais adequada, houve baixa concordância, em média 26, 4%. / 30 primary teeth crowns and 16 composites were used in this investigation. The aim was to compare, in vitro, with a spectrofotometer, the colour unit difference (DE) of the primary teeth and the composites, and also compare, in vitro, through visual analisys, the choice of 3 examinators, the same specimens used in the first test; to compare the spectrofotometric analisys with the visual analisys. The results showed that only the composites Herculite B1, Durafill SL and Filtek A110 B0,5 showed DE lower or equal to 3,5, making clear the restrict colour options in pedodontics. There was a large difference in colour grade among the available commercial brands for the same colour name. The statistical analisys showed that there is significant difference to the comparison of the DE between the different composites (P £ 0,05). By the visual analisys, all the 3 examinators considered the composite Durafill SL, the most close to the teeth colour, followed by the Filltek Z250 B0,5 for examinators 1 and 3 and Filtek A110 B0,5 for examinator 2. In the comparison between the spectrofotometric results and the examinators for the composite that better matched the teeth, there was low agreement with 26,4% in average.

Phytochromes are the photoreceptors mainly responsible for the detection of red and far-red (FR) light and the following responses. HFR1 is a basic helix-loop-helix type putative transcription factor involved in Phytochrome A signaling pathway. First we look at the early phenotype of mutant seedlings lacking a functional HFR1 gene and we show that auxin is involved in the increased hypocotyl phenotype of these seedlings. Northern blots and RT-PCRs showed that ATHB-2, a gene involved in shade avoidance is regulated by HFR1 under FR light. Microarray experiments were performed to find the genes that are early targets of regulation by HFR1.

Para este estudo foram utilizadas 30 coroas de dentes decíduos e 16 diferentes resinas compostas de diversas marcas comerciais. O objetivo foi comparar, in vitro, com o uso do espectrofotômetro, a diferença de unidades de cor (DE) de dentes decíduos e resinas compostas e, também, selecionar, in vitro, através de análise visual de três examinadores, as resinas compostas cujas cores mais se assemelhavam à cor dos dentes, utilizando as mesmas amostras do item anterior. Os resultados apontaram que apenas as resinas Herculite cor B1, Durafill cor SL e Filtek A110 cor B0,5 apresentaram DE menor ou igual a 3,5, demonstrando o restrito número de opções para uso em odontopediatria. Houve uma grande variação de tonalidades das resinas dentro da mesma designação de cor em diferentes marcas comerciais, o que indica a dificuldade do uso da escala de cor. A análise estatística mostrou haver diferença estatisticamente significante na comparação dos DE entre as diferentes resinas, (P £ 0,05). Na análise visual, os três examinadores consideraram a resina Durafill, cor SL, como a resina que mais se aproximou à cor dos dentes, seguida da Filltek Z250, cor B0,5 para os examinadores 1 e 3, e Filtek A110 cor B0,5 para o examinador 2. Na comparação realizada entre os resultados do espectrofotômetro com os examinadores para indicação da resina mais adequada, houve baixa concordância, em média 26, 4%. / 30 primary teeth crowns and 16 composites were used in this investigation. The aim was to compare, in vitro, with a spectrofotometer, the colour unit difference (DE) of the primary teeth and the composites, and also compare, in vitro, through visual analisys, the choice of 3 examinators, the same specimens used in the first test; to compare the spectrofotometric analisys with the visual analisys. The results showed that only the composites Herculite B1, Durafill SL and Filtek A110 B0,5 showed DE lower or equal to 3,5, making clear the restrict colour options in pedodontics. There was a large difference in colour grade among the available commercial brands for the same colour name. The statistical analisys showed that there is significant difference to the comparison of the DE between the different composites (P £ 0,05). By the visual analisys, all the 3 examinators considered the composite Durafill SL, the most close to the teeth colour, followed by the Filltek Z250 B0,5 for examinators 1 and 3 and Filtek A110 B0,5 for examinator 2. In the comparison between the spectrofotometric results and the examinators for the composite that better matched the teeth, there was low agreement with 26,4% in average.

There are no previous studies validating the accuracy and repeatability of ClearMatch photographic shade analysis system. The purpose of this study was to compare the shade matches performed by a photographic shade analysis system (ClearMatch) with conventional visual shade matching method under simulated clinical conditions. Three shade matching methods were used to match twelve shade tabs under simulated clinical conditions using a Vita Classical shade guide: conventional visual shade matching using 3 human raters (VM – Visual method), photographic shade analysis system (CM - ClearMatch) using two different ways of normalizing the image (CM-A2 and CM-ref respectively). Shade matching for all methods was completed at two separate sessions. The Kappa statistic was used to determine the intra-rater and inter-rater agreement. CIELAB values of the shade results were used to produce scatter plots as well as to calculate the color difference (delta E) between VM and CM groups. There was no inter-rater agreement between VM and CM-A2 (k=0.000 and k=0.015 for the first and second sessions respectively) while VM and CM-ref showed weak agreement (k=0.244 and k=0.091 respectively). Intra-rater agreement was strong in all groups VM, CM-A2 and CM-ref (0.705, 0.803 and 0.681 respectively). CM-A2 had 2 (8.3%) shade matches with a delta E of less than 2.6 (clinically imperceptible), while CM-ref had 12 (50.0%) imperceptible matches. CM-A2 had an additional 16 (66.6%) shade matches with delta E of less than 5.5 (clinically acceptable), while CM-ref had 23 (95.8%) additional acceptable matches. There was poor agreement in exact shade matches between conventional visual shade matching method and the photographic shade analysis system. The repeatability of the photographic shade analysis system was shown to be comparable to conventional visual shade matching. Using conventional shade matching as the gold standard, the capability of this photographic shade analysis system to accurately shade match has not been achieved.

Light is the fundamental source of energy and information throughout the plant life cycle. Light signals regulate plant architecture and branching, key processes that determine biomass production and grain yield. Low red (R) to far-red (FR) light ratios (R:FR) perceived by phytochromes serve as a warning signal about impending competition for light resources and lead to shade avoidance responses (SARs), including reduced branching. The R:FR regulates branching in both a bud autonomous and non-bud autonomous manner, however a detailed mechanistic understanding of the process remains unclear. We hypothesized that high R:FR promotes bud outgrowth by differentially regulating branching-related genes (transcriptome) within the axillary bud and that increased apical dominance under low R:FR or with phyB deficiency is mediated by auxin or other novel signal/s. We analyzed the branching phenotype of Arabidopsis Columbia-60000 ecotype in response to different R:FR treatments and conducted a microarray study to identify early (within 3 hours) changes in the transcriptome of buds from different rosette positions in response to altered R:FR. Physiological experiments were also conducted to determine if auxin concentration, transport rate, sensitivity, and establishment of an auxin transport stream were important in determining the branching phenotype of shade avoiding plants. The results revealed that the duration of low R:FR determines plant architecture and the branching phenotype and that bud outgrowth is regulated by the R:FR in a spatial and temporal manner. Low R:FR promoted the elongation of branches at top rosette nodes while it suppressed the outgrowth of axillary buds at lower nodes. High R:FR could reverse the effects of previous low R:FR by promoting the outgrowth of buds from lower axils within 24 hours of treatment. Transcriptomic analysis revealed that the R:FR differentially regulated the expression of genes related to hormone biosynthesis/transport/signaling, cell-cycle regulation and cell wall modification. Cis-elements responsive to light and hormone signaling pathways were overrepresented in several gene clusters. Apical dominance related studies discovered that loss of phyB function results in a slower auxin transport rate, fewer xylem parenchyma cells, and reduced sensitivity to auxin. These results, in addition to estimates of correlative inhibition, suggested that auxin is at least partially responsible for increased apical dominance under low R:FR or with phyB deficiency, but may be acting in conjunction with other undefined regulators.

No description available.

This thesis quantifies aspects of shade tolerance in tree seedlings of species native to the Caledonian pinewood ecosystems of Glen Affric (Highland Region, Inverness-shire). Growth, allocation and morphological responses of 15 species to irradiance under simulated forest canopy light were investigated in a nursery-based shade house experiment. The same responses of four of the 15 species (Ilex aquifolium, Alnus glutinosa, Sorbus aucuparia and Betula pubescens) to different developmental stages of Pinus sylvestris woodland were investigated in the field. The spatial and temporal growth responses of naturally regenerating S. aucuparia seedlings to shade and gap microhabitats were also studied. Data from the shade house experiment enabled further detailed exploration of the relationship between relative growth rates (RGR) and irradiance and potential cross-overs of ranks of growth in high and low light conditions.

Slash-and-burn agriculture is, under conditions with increasing pressure on resources, one cause of deforestation and land degradation. The Mayas of southern Belize use a type of slash-and-burn farming which is currently degrading the environment. On the other hand, cacao cultivation can be an integrated part of multi-storey agroforestry systems, indicated to provide capacity to maintain biodiversity. The Mayas have traditionally farmed cacao and it is now becoming an important cash crop in the district. Institutional stakeholders in Toledo district and six cacao farmers in two Mayan villages was interviewed for this study. The focus was to identify perceived constraints and prospects, as well as considerations of improvements, in shaded cacao cultivation. The farmers who participated in this study produce organic cacao under small-scale farming conditions, growing cacao under a canopy of mainly fruit and timber trees, providing income and food. Banana/plantain (Musa sp.), Salmwood (Cordia alliodora) and Cedar (Cederela odorata) are common shade species. Shade trees are randomly planted and timings for shade management is varying. Many of the farmers experience that their shade management can improve. Weather, disease, income and lack of knowledge are some of the issues in shaded cacao farming in the south of Belize. There is an on-going development of the local cacao market and the organic and Fair Trade production is constantly growing. More attention needs to be given to further research for improvements in shade management, as well as better access to resources for the local cacao farmers.

Graduation date: 1992

Available commercial ceramic brackets are made of alumina either monocrystalline or polycrystalline. One major drawback of these brackets is fracture during archwire torsion or tipping. Another drawback is that each type comes in one shade only: transparent or translucent. Objectives: To fabricate orthodontic brackets from different esthetic materials and evaluate their mechanical properties; to introduce extremely low profile miniature zirconia brackets and evaluate their torsional fracture strength; also, to fabricate brackets in shades comparable to natural tooth shades, and compare them to commercial ceramic brackets under different lights. Materials and Methods: CAD/CAM technology was used to mill brackets from: ParadigmTM MZ100 and LavaTM Ultimate resin composite; Mark II feldspathic porcelain; and In-Ceram® YZ zirconia. The brackets were subjected to two separate tests (torque and tipping). The average moments necessary to fracture the brackets were determined and compared to those of commercial alumina brackets, Mystique® MB and Resolve®. Also, miniature zirconia brackets were fabricated and subjected to torsion till failure. Static fatigue test was performed on standard YZ, MZ100, and Mystique brackets. Brackets were fabricated using CAD/CAM in shade A3 materials: MZ100; Lava Ultimate; and Mark II. Zirconia and alumina brackets were also fabricated and colored. Adobe Photoshop software was used to determine ΔE values between the brackets and A3 acrylic teeth from digital images taken under three different lights (daylight, fluorescent, and incandescent). The shaded brackets were compared to commercial alumina brackets: Inspire ICETM; Radiance PlusTM; Avex® CX; and Mystique® MB. Results: Standard zirconia brackets had the highest torsional and tipping strength among the tested esthetic brackets. Miniature zirconia brackets showed comparable or even statistically significantly higher resistance to archwire torsion than commercial alumina brackets. Standard zirconia brackets showed the highest survival rate of 83%. Under daylight, Radiance Plus and Lava Ultimate brackets had the smallest mean ΔE values. Lava Ultimate brackets had the smallest mean ΔE under fluorescent and incandescent light. Conclusions: Esthetic brackets can be fabricated in extremely low profile and smaller dimensions from zirconia with fracture strength comparable to the bulkier commercial alumina brackets. Also, brackets can be produced in natural tooth shades enhancing their esthetic appearance. / 2018-09-28T00:00:00Z