Estimating uniaxial compressive strength, density and porosity of rocks from the p-wave velocity measurements in-situ and in the laboratory

Knowledge of the physical properties of rock masses is fundamental for the economics and safety of mining projects. The determination of these properties in rock samples in the laboratory requires time, expensive equipment and qualified personnel, which considerably increases the information's cost. Indirect methods were developed to obtain properties related to rock masses, which have been shown to be a viable alternative to traditional procedures. The determination of the compressional mechanical wave velocity (Vp) and subsequent correlation with lithological mechanical properties are indirectly obtained. This study’s objective was to obtain correlations between Vp and the resistance to uniaxial compression, UCS (Unconfined Compressive Strength), as well as the density and porosity of the siltstone and sandstone lithologies present in the coalfield of Candiota, located in the southern region of Rio Grande do Sul, Brazil. The Vp records were obtained in laboratory samples, using ultrasonic velocity sensors, and in-situ by geophysical well logging (directly in boreholes). The results indicate the possibility of using Vp to determine the physical parameters of the investigated lithologies. In the specific case of the correlations between Vp and Unconfined Compressive Strength, determination coefficients R2 above 0.70 were obtained, indicating sufficiently high reliability for using this information (e.g. in roof support projects). The correlation between Vp and density was also high

Clopidogrel Enhances Periodontal Repair in Rats Through Decreased Inflammation

Aim We hypothesized that platelet inactivation induced by drugs might interfere with periodontal repair in experimental periodontitis by suppressing the release of biological mediators from platelets at the site of injury. Material and Methods 60 rats were randomly assigned to 6 groups (n=10) and ligatures were placed around lower first molars of three groups. The other three groups were used as negative controls. Ligatures were removed after 10 days of periodontitis induction and all groups were submitted to treatment with aspirin (Asp) (30 mg/kg), clopidogrel (Clop) (75 mg/kg) or NaCl 0.9% intragastrically once daily for 3 days. Periodontal tissue was assessed by the measurement of CXCL12, CXCL4, CCL5 and PDGF by ELISA; histomorphometric analysis of PMN infiltration, attachment loss, bone loss and osteoclast numbers and quantification of blood vessels by imunnohistochemistry. Results During periodontal repair and treatment with NaCl 0.9%, CCL5 was decreased and CXCL12 increased when compared to negative control groups. Asp and Clop did not affect CCL5 expression, decreased CXCL12 but only Clop decreased CXCL4 and PDGF content compared to saline-treated animals. Clop increased blood vessel number, reduced PMN count, and decreased attachment and bone loss, also decreased osteoclast number in animals submitted or not to periodontal repair. Conclusion Systemic administration of Clop during 3 days improved the repair process associated with experimental periodontal disease, suggesting that it may have therapeutic value under situations where tissues undergo a transition from inflammation to repair

Retinal topography and microhabitat diversity in a group of dragon lizards

The well‐studied phylogeny and ecology of dragon lizards and their range of visually mediated behaviors provide an opportunity to examine the factors that shape retinal organization. Dragon lizards consist of three evolutionarily stable groups based on their shelter type, including burrows, shrubs, and rocks. This allows us to test whether microhabitat changes are reflected in their retinal organization. We examined the retinae of three burrowing species (Ctenophorus pictus, C. gibba, and C. nuchalis), and three species that shelter in rock crevices (C. ornatus, C. decresii, and C. vadnappa). We used design‐based stereology to sample both the photoreceptor array and neurons within the retinal ganglion cell layer to estimate areas specialized for acute vision. All species had two retinal specializations mediating enhanced spatial acuity: a fovea in the retinal center and a visual streak across the retinal equator. Furthermore, all species featured a dorsoventrally asymmetric photoreceptor distribution with higher photoreceptor densities in the ventral retina. This dorsoventral asymmetry may provide greater spatial summation of visual information in the dorsal visual field. Burrow‐dwelling species had significantly larger eyes, higher total numbers of retinal cells, higher photoreceptor densities in the ventral retina, and higher spatial resolving power than rock‐dwelling species. C. pictus, a secondary burrow‐dwelling species, was the only species that changed burrow usage over evolutionary time, and its retinal organization revealed features more similar to rock‐dwelling species than other burrow‐dwelling species. This suggests that phylogeny may play a substantial role in shaping retinal organization in Ctenophorus species compared to microhabitat occupation

Retinal ganglion cell topography and spatial resolving power in African megachiropterans: influence of roosting microhabitat and foraging

Megachiropteran bats (megabats) show remarkable diversity in microhabitat occupation and trophic specializations, but information on how vision relates to their behavioral ecology is scarce. Using stereology and retinal wholemounts, we measured the topographic distribution of retinal ganglion cells and determined the spatial resolution of eight African megachiropterans with distinct roosting and feeding ecologies. We found that species roosting in open microhabitats have a pronounced streak of high retinal ganglion cell density, whereas those favoring more enclosed microhabitats have a less pronounced streak (or its absence in Hypsignathus monstrosus). An exception is the cave-dwelling Rousettus aegyptiacus, which has a pronounced horizontal streak that potentially correlates with its occurrence in more open environments during foraging. In all species, we found a temporal area with maximum retinal ganglion cell density (∼5,000-7,000 cells/mm ) that affords enhanced resolution in the frontal visual field. Our estimates of spatial resolution based on peak retinal ganglion cell density and eye size (∼6-12 mm in axial length) range between ∼2 and 4 cycles/degree. Species that occur in more enclosed microhabitats and feed on plant material have lower spatial resolution (∼2 cycles/degree) compared with those that roost in open and semiopen areas (∼3-3.8 cycles/degree). We suggest that the larger eye and concomitant higher spatial resolution (∼4 cycles/degree) in H. monstrosus may have facilitated the carnivorous aspect of its diet. In conclusion, variations in the topographic organization and magnitude of retinal ganglion density reflect the specific ecological needs to detect food/predators and the structural complexity of the environments. J. Comp. Neurol. 525:186-203, 2017. © 2016 Wiley Periodicals, Inc

Evaluation of the use of geophysical profiles for recognition and determination of coal layers thicknesses in deposits of Rio Grande do Sul, Southern Brazil

Este estudo investiga a possibilidade do uso da perfilagem geofísica de gama natural e resistividade na discriminação de estratos carbonosos, em relação a outras litologias presentes em quatro depósitos de carvão localizados no Rio Grande do Sul (áreas B3, Calombo, Cerro e Seival). Uma vez observada a possibilidade de identificação dos estratos carbonosos com estes dois perfis geofísicos apenas, fez-se uma verificação da acuracidade na determinação das espessuras das camadas de carvão. Neste contexto, as espessuras das camadas de carvão foram comparadas com as espessuras observadas em testemunhos de sondagem, sendo que o reconhecimento das assinaturas das camadas pode ser feito com boa acuracidade para todos os depósitos, exceto no depósito do Cerro, onde o sinal do carvão confunde-se com o sinal de arenitos, inviabilizando muitas vezes a discriminação. Ressalte-se a importância deste tipo de avaliação, especialmente quanto às espessuras de camadas de carvão no planejamento de mina de curto prazo, onde não é exequível a sondagem com recuperação de testemunhos em bancadas de lavra simultaneamente ao processo extração de carvão, em função da demora da atividade de sondagem e custos elevados.The study investigates the possibility of using geophysical well logging of natural gamma and resistivity in the identification of carbonaceous strata in relation to other lithologies present in four coal deposits located in Rio Grande do Sul (B3, Calombo, Cerro and Seival). Once the possibility of identification of the carbonaceous strata with these two geophysical profiles was observed, a verification of the accuracy in the determination of the thicknesses of the coal seams was performed. In this context, the thicknesses of the coal seams were compared with the thicknesses observed in recovered core samples and the recognition of the signatures of the seams was possible with good accuracy for all deposits, except in the Cerro deposit, where the signature of the coal was confused with the signature of sandstones, often making it impossible to discriminate. It should be stressed the importance of this type of evaluation, especially regarding the thickness of coal seams in the short-term mine planning, where drilling with core sample recovery is not feasible simultaneously with the extraction process, due to the delays in drilling and high costs

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Topographic specializations in the retinal ganglion cel layer of Australian passerines

Thornbills, honeyeaters, and silvereyes represent an abundant group of Australian passerines, whose diversity in niche differentiation suggests a pivotal role for vision. Using stereological methods and retinal wholemounts, we studied the topographic distribution of neurons in the ganglion cell layer of insectivorous, nectarivorous, and frugivorous species occupying terrestrial and arboreal microhabitats. All species studied have a central convexiclivate fovea (peak densities from 130,000 to 160,000 cells/mm²), which is shallow in the terrestrial/insectivorous yellow-rumped thornbill and deep in the arboreal/nectarivorous honeyeaters and frugivorous silvereye. Surrounding the fovea, neuronal densities in the ganglion cell layer form a broadly ovoid and asymmetric plateau in the yellow-rumped thornbill and a more restricted, circular and symmetric plateau in the other species. These differences in the plateau organization may reflect specific needs to locate food on the ground or among dense vegetation. We also found a temporal area (peak densities from 43,000 to 54,000 cells/mm²) across species, which increases spatial resolution in the frontal visual field and assists with foraging. Using microtubule-associated protein 2 (MAP2) immunohistochemistry, we detected a higher concentration of giant ganglion cells forming an area gigantocellularis in the temporal retina of all species. Giant ganglion cell densities also form a horizontal streak in all species, except in the yellow-rumped thornbill, which has an unusual increase toward the retinal periphery. In the yellow-rumped thornbill and silvereye, giant ganglion cells also peak in the nasal retina. We suggest that these topographic variations afford differential sampling of motion signals for the detection of predators.20 page(s

Monitoramento geofísico de desmonte de rocha com utilização de explosivos em condições de risco elevado em zona urbana

Esse trabalho introduz uma metodologia baseada na aplicação de métodos geofísicos para avaliação do risco associado ao desmonte de rochas com utilização de explosivos em áreas urbanas com alta densidade demográfica e situação de risco elevada. A utilização de GPR (ground penetrating radar) forneceu informações relacionadas com as condições geomecânicas do terreno, tais como densidade de fraturas, enquanto que o monitoramento sismográfico auxiliou no controle de vibrações geradas pelo desmonte, mantendo-se essas vibrações abaixo dos limites estabelecidos na legislação brasileira. Resultados de caracterização geomecânica do subsolo e do monitoramento de vibrações são descritos e discutidos. A metodologia proposta é ilustrada em um estudo de caso.This paper presents an application of geophysical methods to evaluate the risk associated with blasting used during rock excavation at highly populated and risky urban areas. Ground penetration radar provided information related to rock mechanics such as fracture density, whilst seismographic readings helped in maintaining vibration levels below maximum limits. Results of in situ soil and rock characterization and vibration control are reported and discussed. The methodology proposed is illustrated in case study