724 research outputs found

    Integrated Geomechanical and Digital Photogrammetric Survey in the Study of Slope Instability Processes of a Flysch Sea Cliff (Debeli Rtič Promontory, Slovenia)

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    This work presents an integrated study approach that combines the results of a geomechanical survey with data obtained using digital photogrammetry (DP), to assess slope instability processes affecting a sea cliff at the Debeli Rtič promontory (Slovenia). The investigated cliff is 4–18 m-high and is made up of an alternation of sandstones and marlstones belonging to the Flysch Formation of Trieste, which is Eocene in age. The studied cliff was subjected to localized slope failures that occurred in the past and is currently subject to frequent rock collapses, thus resulting in its partial and episodic retreat. Field evidence acquired through a traditional survey was integrated with outputs of the DP technique based on 1399 images that were collected using both a commercial unmanned aerial vehicle (UAV) and a mobile phone (MP). UAV-derived images were useful for performing rock mass structure analysis in the upper part of the investigated cliff, where the traditional survey was not possible due to hazardous operating conditions. In addition, the use of a MP was observed to be a useful tool for the rapid collection of images at the toe of unsafe marine cliff environments. This study highlights that UAV-DP and MP-DP techniques can only be effective if the outcomes obtained from the 3D model reconstruction are validated by direct measurements acquired by means of the traditional field survey, thus avoiding improper or even erroneous results while enlarging the amount of data and the area of investigation. The study approach presented herein allowed for the assessment of slope instabilities affecting the Flysch Sea cliff, whose retreat is caused by the combined action of marine erosion and slope gravitational processes

    Treatment effects of fixed functional appliances alone or in combination with multibracket appliances: A systematic review and meta-analysis

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    "Abstract Objective: To assess skeletal and dentoalveolar effects of fixed functional appliances, alone or in combination with multibracket appliances (comprehensive treatment), on Class II malocclusion in pubertal and postpubertal patients. Materials and Methods: Literature survey was conducted using the Medline, SCOPUS, LILACS, and SciELO databases and The Cochrane Library, and through a manual search. The studies retrieved had to have a matched untreated control group. No restrictions were set regarding the type of fixed appliance, treatment length, or to the cephalometric analysis used. Data extraction was mostly predefined at the protocol stage by two authors. Supplementary mandibular elongation was used for the meta-analysis. Results: Twelve articles qualified for the final analysis of which eight articles were on pubertal patients and four were on postpubertal patients. Overall supplementary total mandibular longationsas mean (95 confidence interval) were 1.95 mm (1.47 to 2.44) and 2.22 mm (1.63to 2.82) among pubertal patients and -1.73 mm (-2.60 to -0.86) and 0.44 mm (-0.78 to 1.66) among postpubertal patients, for the functional and comprehensive treatments, respectively. For pubertal subjects, maxillary growth restraint was also reported. Nevertheless, skeletal effects alone would not account for the whole Class II correction even in pubertal subjects with dentoalveolar effects always present. Conclusions: Fixed functional treatment is effective in treating Class II malocclusion with skeletal effects when performed during the pubertal growth phase, very few data are available on postpubertal patients.

    Integrated Geomechanical and Digital Photogrammetric Survey in the Study of Slope Instability Processes of a Flysch Sea Cliff (Debeli Rtic Promontory, Slovenia)

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    This work presents an integrated study approach that combines the results of a geomechanical survey with data obtained using digital photogrammetry (DP), to assess slope instability processes affecting a sea cliff at the Debeli Rtic promontory (Slovenia). The investigated cliff is 4-18 m-high and is made up of an alternation of sandstones and marlstones belonging to the Flysch Formation of Trieste, which is Eocene in age. The studied cliff was subjected to localized slope failures that occurred in the past and is currently subject to frequent rock collapses, thus resulting in its partial and episodic retreat. Field evidence acquired through a traditional survey was integrated with outputs of the DP technique based on 1399 images that were collected using both a commercial unmanned aerial vehicle (UAV) and a mobile phone (MP). UAV-derived images were useful for performing rock mass structure analysis in the upper part of the investigated cliff, where the traditional survey was not possible due to hazardous operating conditions. In addition, the use of a MP was observed to be a useful tool for the rapid collection of images at the toe of unsafe marine cliff environments. This study highlights that UAV-DP and MP-DP techniques can only be effective if the outcomes obtained from the 3D model reconstruction are validated by direct measurements acquired by means of the traditional field survey, thus avoiding improper or even erroneous results while enlarging the amount of data and the area of investigation. The study approach presented herein allowed for the assessment of slope instabilities affecting the Flysch Sea cliff, whose retreat is caused by the combined action of marine erosion and slope gravitational processes

    The Effect of the P/Si Ratio on the Preparation and Properties of Phosphoric Acid-Metakaolin Geopolymers

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    The present research deals with the production and characterization of geopolymers prepared by mixing metakaolin, different amounts of phosphoric acid solution and water. Hardening was performed by aging the geopolymeric pastes in a climatic chamber. The workability of the pastes has been improved while the H2O/total solid content has been kept constant and the P/Si ratio increased. However, such a benefit implies considerable heat output, which must be controlled in order to limit the formation of extended fractures. The compressive strength of the hardened materials increases with increasing P/Si ratio at a constant H2O/total solid content, whereas their strength decreases with increasing H2O/ total solid content at a constant P/Si ratio. The open macroporosity, which is directly dependent on the total amount of water added to the geopolymeric pastes, may explain the above results better than the nano/microporosity and/or chemical bonds that contribute to building up the materials\u2019 textural features

    Avaliação de linhagens, materiais comerciais e duas populações de milho para tolerância a alumínio.

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    Neste trabalho realizou-se a avaliacao da tolerancia a Al (4,5 mg.l) de 39 linhagens, 98 materiais comerciais, 167 progenies de uma populacao IAC-Maya e de 466 progenies de uma populacao IAC-Genetica, usando-se a tecnica de solucao nutritiva. Foram usadas na avaliacao as características ICR (indice de crescimento da radicula = comprimento relativo da radicula -CRR (CR+Al.CR-Al)- multiplicado por comprimento relativo da raiz secundaria mais longa - CRRSML (CRSML+Al/CRSML-Al) e CLR (comprimento liquido da radicula = diferenca entre os valores de comprimento da radicula - CR - obtidos no inicio e fim do periodo de crescimento das plantas em presenca de Al). As linhagens e as progenies da populacao IAC-Maya a de milho foram avaliadas através do ICR enquanto que os materiais comerciais e as progenies da populacao IAC-Genetica foram avaliados pelos valores de CLR. Os controles utilizados foram IAC HS1227 (tolerante a Al) e IAC HS7777 (sensivel a Al). O metodo de solucao nutritiva foi eficiente na diferenciacao da tolerancia a Al dentre os materiais testados, evidenciando a ocorrencia de ampla variabilidade genetica para essa caracteristica. As seguintes linhagens e materiais comerciais apresentaram tolerancia a Al (4,5 mg/l): Porto Rico 70. D,2, IP 38-5-3, IP 365-4-I, IA 2992-3-1-2-3, Vic 3-2-3-30-V-6, 490, 519, 532, 536-2 e 820 (linhagens) e AG 82, AG 260, AGROMEM 1022, ASGROW 1255, DINA 03S, DINA 47, IAC Hmd 7974, SS 1243 e UNICAMP 720 (materiais comerciais)

    Ocorrência de adultos de Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae) em pontos comerciais na área urbana de Vacaria-RS.

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    Este estudo teve como objetivos avaliar a ocorrência de exemplares adultos de D. suzukii nas proximidades de mercados de comercialização de frutas em área urbana
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