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Despite the well-established nature of non-destructive testing (NDT) technologies, autonomous monitoring systems are still in high demand. The solution lies in harnessing the potential of intelligent structures, particularly in industries like aeronautics. Substantial downtime occurs due to routine maintenance, leading to lost revenue when aircraft are grounded for inspection and repairs. This article explores an innovative approach using intelligent materials to enhance condition-based maintenance, ultimately cutting life-cycle costs. The study emphasizes a paradigm shift toward structural health monitoring (SHM), utilizing embedded sensors for real-time monitoring. Active thin film piezoelectric materials are proposed for their integration into composite structures. The work evaluates passive sensing through acoustic emission (AE) signals and active sensing using Lamb wave propagation, presenting amplitude-based and frequency domain approaches for damage detection. A comprehensive signal processing approach is presented, and the damage index and damage size correlation function are introduced to enable continuous monitoring due to their sensitivity to changes in material properties and defect severity. Additionally, finite element modeling and experimental validation are proposed to enhance their understanding and applicability. This research contributes to developing more efficient and cost-effective aircraft maintenance approaches through SHM, addressing the competitive demands of the aeronautic industry.
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We demonstrate interleaved sampling by multiplexing conical subshells within the tomosynthesis and raster scanning a phantom through a 150â kV shell X-ray beam. Each view comprises pixels sampled on a regular 1 mm grid, which is then upscaled by padding with null pixels before tomosynthesis. We show that upscaled views comprising 1% sample pixels and 99% null pixels increase the contrast transfer function (CTF) computed from constructed optical sections from approximately 0.6 line pairs/mm to 3 line pairs/mm. The driver of our method is to complement work concerning the application of conical shell beams to the measurement of diffracted photons for materials identification. Our approach is relevant to time-critical, and dose-sensitive analytical scanning applications in security screening, process control and medical imaging.
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As people, animals and materials are transported across increasingly large distances in a globalized world, threats to our biosecurity and food security are rising. Aotearoa New Zealand is an island nation with many endemic species, a strong local agricultural industry, and a need to protect these from pest threats, as well as the economy from fraudulent commodities. Mitigation of such threats is much more effective if their origins and pathways for entry are understood. We propose that this may be addressed in Aotearoa using strontium isotope analysis of both pests and products. Bioavailable radiogenic isotopes of strontium are ubiquitous markers of provenance that are increasingly used to trace the origin of animals and plants as well as products, but currently a baseline map across Aotearoa is lacking, preventing use of this technique. Here, we have improved an existing methodology to develop a regional bioavailable strontium isoscape using the best available geospatial datasets for Aotearoa. The isoscape explains 53% of the variation (R2 = 0.53 and RMSE = 0.00098) across the region, for which the primary drivers are the underlying geology, soil pH, and aerosol deposition (dust and sea salt). We tested the potential of this model to determine the origin of cow milk produced across Aotearoa. Predictions for cow milk (n = 33) highlighted all potential origin locations that share similar 87Sr/86Sr values, with the closest predictions averaging 7.05 km away from their true place of origin. These results demonstrate that this bioavailable strontium isoscape is effective for tracing locally produced agricultural products in Aotearoa. Accordingly, it could be used to certify the origin of Aotearoa's products, while also helping to determine if new pest detections were of locally breeding populations or not, or to raise awareness of imported illegal agricultural products.
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Isótopos de Estroncio , Estroncio , Animales , Bioaseguramiento , Humanos , Nueva Zelanda , Estroncio/análisis , Isótopos de Estroncio/análisisRESUMEN
Water-rock interactions are relevant to planetary habitability, influencing mineralogical diversity and the production of organic molecules. We examine carbonates and silicates in the martian meteorite Allan Hills 84001 (ALH 84001), using colocated nanoscale analyses, to characterize the nature of water-rock reactions on early Mars. We find complex refractory organic material associated with mineral assemblages that formed by mineral carbonation and serpentinization reactions. The organic molecules are colocated with nanophase magnetite; both formed in situ during water-rock interactions on Mars. Two potentially distinct mechanisms of abiotic organic synthesis operated on early Mars during the late Noachian period (3.9 to 4.1 billion years ago).
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The peri-urban interface (PUI) exhibits characteristic qualities of both urban and rural regions, and this complexity has meant that risk assessments and long-term planning for PUI are lagging, despite these areas representing new developing settlement frontiers. This study aims to address this knowledge gap by modifying an existing approach to quantify and assess flood risk. The risk triangle framework was used to map exposure, vulnerability and biophysical variables; however, in a novel application, the risk triangle framework was adapted by presuming that there is a variation in the degree of exposure, vulnerability and biophysical variables. Within Australia and globally, PUIs are often coastal, and flood risk associated with rainfall and coastal inundation poses considerable risk to communities in the PUI; these risks will be further exacerbated should projections of increasing frequency of extreme rainfall events and accelerating sea-level rise eventuate. An indicator-based approach using the risk triangle framework that maps flood hazard, exposure and vulnerability was used to integrate the biophysical and socio-economic flooding risk for communities in PUI of the St Georges Basin and Sussex Inlet catchments of south-eastern Australia. Integrating the flood risk triangle with future scenarios of demographic and climate change, and considering factors that contribute to PUI flood risk, facilitated the identification of planning strategies that would reduce the future rate of increase in flood risk. These planning strategies are useful for natural resource managers and land use planners across Australia and globally, who are tasked with balancing socio-economic prosperity for a changing population, whilst maintaining and enhancing ecosystem services and values. The indicator-based approach used in this study provides a cost-effective first-pass risk assessment and is a valuable tool for decision makers planning for flood risk across PUIs in NSW and globally.
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Mangroves are among the most carbon-dense ecosystems on the planet. The capacity of mangroves to store and accumulate carbon has been assessed and reported at regional, national and global scales. However, small-scale sampling is still revealing 'hot spots' of carbon accumulation. This study reports one of these hotspots, with one of the largest-recorded carbon stocks in mangroves associated with sinkholes (cenotes) in the Yucatan Peninsula, Mexico. We assessed soil organic carbon (SOC) stocks, sequestration rates and carbon origin of deep peat soils (1 to 6 m). We found massive amounts of SOC up to 2792 Mg C ha-1, the highest value reported in the literature so far. This SOC is primarily derived from highly preserved mangrove roots and has changed little since its deposition, which started over 3220 years ago (±30 BP). Most cenotes are owned by Mayan communities and are threatened by increased tourism and the resulting extraction and pollution of groundwater. These hot spots of carbon sequestration, albeit small in area, require adequate protection and could provide valuable financial opportunities through carbon-offsetting mechanisms and other payments for ecosystem services.
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Secuestro de Carbono , Ecosistema , Carbono , México , Suelo , HumedalesRESUMEN
The response of mangroves to high rates of relative sea level rise (RSLR) is poorly understood. We explore the limits of mangrove vertical accretion to sustained periods of RSLR in the final stages of deglaciation. The timing of initiation and rate of mangrove vertical accretion were compared with independently modeled rates of RSLR for 78 locations. Mangrove forests expanded between 9800 and 7500 years ago, vertically accreting thick sequences of organic sediments at a rate principally driven by the rate of RSLR, representing an important carbon sink. We found it very likely (>90% probability) that mangroves were unable to initiate sustained accretion when RSLR rates exceeded 6.1 millimeters per year. This threshold is likely to be surpassed on tropical coastlines within 30 years under high-emissions scenarios.
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Elevación del Nivel del Mar , HumedalesRESUMEN
Sindbis virus (SINV) produces the small membrane protein TF from the 6K gene via a (-1) programmed ribosomal frameshifting. While several groups have shown that TF-deficient virus exhibits reduced virulence, the mechanism(s) by which this occurs remain unknown. Here, we demonstrate a role for TF in antagonizing the host interferon response. Using wild-type and type 1 interferon receptor-deficient mice and primary cells derived from these animals, we show that TF controls the induction of the host interferon response at early times during infection. Loss of TF production leads to elevated interferon and a concurrent reduction in viral loads with a loss of pathogenicity. Palmitoylation of TF has been shown to be important for particle assembly and morphology. We find that palmitoylation of TF also contributes to the ability of TF to antagonize host interferon responses as dysregulated palmitoylation of TF reduces virulence in a manner similar to loss of TF.
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Interferón Tipo I/biosíntesis , Virus Sindbis/inmunología , Virus Sindbis/metabolismo , Proteínas Virales/inmunología , Proteínas Virales/metabolismo , Infecciones por Alphavirus/genética , Infecciones por Alphavirus/inmunología , Infecciones por Alphavirus/virología , Animales , Femenino , Genes Virales , Interacciones Microbiota-Huesped/genética , Interacciones Microbiota-Huesped/inmunología , Interacciones Microbiota-Huesped/fisiología , Lipoilación , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación , Receptor de Interferón alfa y beta/deficiencia , Receptor de Interferón alfa y beta/genética , Receptor de Interferón alfa y beta/inmunología , Virus Sindbis/genética , Proteínas Virales/genética , Virulencia/genética , Virulencia/inmunología , Virulencia/fisiologíaRESUMEN
PURPOSE: Intrathecal baclofen (ITB) treatment is used with increasing frequency in the cerebral palsy population. We describe the complications of ITB treatment, the incidence of complications, and our experience with their treatment. METHODS: In a period of 15 years, 341 paediatric patients with cerebral palsy treated with ITB were evaluated. Device problems associated with the catheter or pump, or infection and complications such as cerebrospinal fluid (CSF) leak and postdural spinal headache, were reviewed. Infection was classified as early (≤ 90 days) or late (> 90 days) according to the time of onset. RESULTS: The infection rate was 6.9% per procedure (50/720) and 14.6% per patient (50/341) over a mean 6.3 ± 3.9 years. There was a positive correlation between the risk of infection and preoperative comorbidities including epilepsy/seizure history, feeding tube, and mixed type cerebral palsy (p < 0.05, p = 0.03, p = 0.01, respectively). Eighty-five (24.9%) patients experienced 90 CSF leak episodes; 61 of these 85 patients had headache complaints as a result of CSF leak. There was a positive correlation between the risk of early infection and CSF leak (p < 0.05). CONCLUSIONS: The most common complication related to ITB was associated with pump and catheter problems. The rate of complications with the use of ITB is relatively high; however, based on the literature reports, it is the most effective treatment for severe spasticity and dystonia in patients with severe cerebral palsy. LEVEL OF EVIDENCE: III.
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We combine diffraction and absorption tomography by raster scanning samples through a hollow cone of pseudo monochromatic X-rays with a mean energy of 58.4 keV. A single image intensifier takes 90x90 (x,y) snapshots during the scan. We demonstrate a proof-of-principle of our technique using a heterogeneous three-dimensional (x,y,z) phantom (90x90x170 mm3) comprised of different material phases, i.e., copper and sodium chlorate. Each snapshot enables the simultaneous measurement of absorption contrast and diffracted flux. The axial resolution was ~1 mm along the (x,y) orthogonal scan directions and ~7 mm along the z-axis. The tomosynthesis of diffracted flux measurements enable the calculation of d-spacing values with ~0.1 Å full width at half maximum (FWHM) at ~2 Å. Thus the identified materials may be color-coded in the absorption optical sections. Characterization of specific material phases is of particular interest in security screening for the identification of narcotics and a wide range of homemade explosives concealed within complex "everyday objects." Other potential application areas include process control and biological imaging.
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We introduce a new high-energy X-ray diffraction tomography technique for volumetric materials characterization. In this method, a conical shell beam is raster scanned through the samples. A central aperture optically couples the diffracted flux from the samples onto a pixelated energy-resolving detector. Snapshot measurements taken during the scan enable the construction of depth-resolved dark-field section images. The calculation of d-spacing values enables the mapping of material phase in a volumetric image. We demonstrate our technique using five ~15 mm thick, axially separated samples placed within a polymer tray of the type used routinely in airport security stations. Our method has broad analytical utility due to scalability in both scan size and X-ray energy. Additional application areas include medical diagnostics, materials science, and process control.
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The sources and nature of organic carbon on Mars have been a subject of intense research. Steele et al. (2012) showed that 10 martian meteorites contain macromolecular carbon phases contained within pyroxene- and olivine-hosted melt inclusions. Here, we show that martian meteorites Tissint, Nakhla, and NWA 1950 have an inventory of organic carbon species associated with fluid-mineral reactions that are remarkably consistent with those detected by the Mars Science Laboratory (MSL) mission. We advance the hypothesis that interactions among spinel-group minerals, sulfides, and a brine enable the electrochemical reduction of aqueous CO2 to organic molecules. Although documented here in martian samples, a similar process likely occurs wherever igneous rocks containing spinel-group minerals and/or sulfides encounter brines.
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Recent studies using direct live cell imaging have reported that individual B lymphocytes have correlated transit times between their G1 and S/G2/M phases. This finding is in contradiction with the influential model of Smith and Martin that assumed the bulk of the total cell cycle time variation arises in the G1 phase of the cell cycle with little contributed by the S/G2/M phase. Here we extend these studies to examine the relation between cell cycle phase lengths in two B lymphoma cell lines. We report that transformed B lymphoma cells undergo a short G1 period that displays little correlation with the time taken for the subsequent S/G2/M phase. Consequently, the bulk of the variation noted for total division times within a population is found in the S/G2/M phases and not the G1 phase. Models that reverse the expected source of variation and assume a single deterministic time in G1 followed by a lag + exponential distribution for S/G2/M fit the data well. These models can be improved further by adopting two sequential distributions or by using the stretched lognormal model developed for primary lymphocytes. We propose that shortening of G1 transit times and uncoupling from other cell cycle phases may be a hallmark of lymphocyte transformation that could serve as an observable phenotypic marker of cancer evolution.
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Linfocitos B/citología , Ciclo Celular , Animales , Línea Celular Transformada , Línea Celular Tumoral , Células Clonales , Fluorescencia , Fase G1 , Humanos , Cinética , Ratones , Modelos Biológicos , UbiquitinaciónRESUMEN
PURPOSE: Foot and ankle deformities are common orthopaedic disorders in children with Down syndrome. However, radiographic measurements of the foot and ankle have not been previously reported. The aim of this study is to describe the foot and ankle deformity in children with Down syndrome. METHODS: Children who had foot and ankle radiographs in the standing weight-bearing position were selected. Three groups of patients were identified. The relationship of radiographic measurements with age, body mass index and pain is discussed. In all, 41 children (79 feet) had foot radiographs and 60 children (117 ankles) had ankle radiographs, with 15 children overlapping between Groups I and II. RESULTS: In Group I, hallux valgus deformity was seen before ten years of age and hallux valgus angle increased afterwards. Metatarsus adductus angle showed a significant increase (p = 0.006) with obesity and was higher in patients who had foot pain (p = 0.05). In Group II, none of the ankle measurements showed a significant difference with age or body mass index percentiles. Tibiotalar angle (TTA) and medial distal tibial angle (MDTA) were higher in patients who had ankle pain. In Group III, correlation analysis was performed between the different measurements with the strongest correlations found between TTA and MDTA. CONCLUSION: In children with Down syndrome, radiographic evaluation of the foot and ankle reveals higher prevalence of deformities than clinical examination. However, foot and ankle radiographs are needed only for symptomatic children with pain and gait changes. LEVEL OF EVIDENCE: Level IV - Prognostic Study.
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PURPOSE: Data on the benefits of perioperative prophylactic antibiotics in the paediatric population are lacking. In this study, we aimed to assess the rate of infection after isolated soft-tissue procedures in patients with cerebral palsy with and without preoperative prophylactic antibiotics between 2009 and 2015. METHODS: We reviewed the records of all children with cerebral palsy who underwent isolated soft-tissue procedures (on the upper and lower limb) at our hospital between 2009 and 2015. Children with at least 30-day postoperative follow-up were included. Children who had groin incisions were excluded. RESULTS: Two groups were identified: the antibiotic group (77 children with 203 incisions and 343 procedures) had one surgical site infection; the no-antibiotic group (48 children with 102 incisions and 177 procedures) had no surgical site infections. CONCLUSION: These results suggest that the use of preoperative antibiotics does not change the rate of postoperative surgical site infections. LEVEL OF EVIDENCE: Level III therapeutic study.
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Integrin α4ß7 mediates the trafficking of leukocytes, including CD4+ T cells, to lymphoid tissues in the gut. Virus mediated damage to the gut is implicated in HIV and SIV mediated chronic immune activation and leads to irreversible damage to the immune system. We employed an immuno-PET/CT imaging technique to evaluate the impact of an anti-integrin α4ß7 mAb alone or in combination with ART, on the distribution of both SIV infected cells and CD4+ cells in rhesus macaques infected with SIV. We determined that α4ß7 mAb reduced viral antigen in an array of tissues of the lung, spleen, axillary, and inguinal lymph nodes. These sites are not directly linked to α4ß7 mediated homing; however, the most pronounced reduction in viral load was observed in the colon. Despite this reduction, α4ß7 mAb treatment did not prevent an apparent depletion of CD4+ T cells in gut in the acute phase of infection that is characteristic of HIV/SIV infection. However, α4ß7 mAb appeared to facilitate the preservation or restoration of CD4+ T cells in gut tissues at later stages of infection. Since damage to the gut is believed to play a central role in HIV pathogenesis, these results support further evaluation of α4ß7 antagonists in the study and treatment of HIV disease.
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Linfocitos T CD4-Positivos/inmunología , Colon/virología , Infecciones por VIH/inmunología , VIH-1/fisiología , Síndrome de Inmunodeficiencia Adquirida del Simio/inmunología , Virus de la Inmunodeficiencia de los Simios/fisiología , Animales , Anticuerpos Monoclonales/metabolismo , Proteínas de la Membrana Bacteriana Externa , Linfocitos T CD4-Positivos/virología , Supervivencia Celular , Supresión Clonal , Modelos Animales de Enfermedad , Humanos , Integrinas/inmunología , Macaca , Receptores de Superficie Celular , Carga ViralRESUMEN
We demonstrate a novel imaging architecture to collect range encoded diffraction patterns from overlapping samples in a single conical shell projection. The patterns were measured in the dark area encompassed by the beam via a centrally positioned aperture optically coupled to a pixelated energy-resolving detector. We show that a single exposure measurement of 0.3 mAs enables d-spacing values to be calculated. The axial positions of the samples were not required and the resultant measurements were robust in the presence of crystallographic textures. Our results demonstrate rapid volumetric materials characterization and the potential for a direct imaging method, which is of great relevance to applications in medicine, non-destructive testing and security screening.
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PURPOSE: Achondroplasia is the most common form of skeletal dysplasia, affecting more than 250 000 individuals worldwide. In these patients, the developing knee undergoes multiple anatomical changes. The purpose of this study was to characterise the intra-articular knee anatomy in children with achondroplasia who underwent knee arthroscopy. METHODS: Records of achondroplasia patients who underwent knee arthroscopy between 2009 and 2014 were reviewed. Demographic data, operative reports, follow-up notes, MRI and arthroscopy images were reviewed. Bony, cartilaginous and ligamentous changes were noted. The trochlea sulcus angle was measured from intra-operative arthroscopic images. RESULTS: A total of 12 knee arthroscopies in nine patients were performed. The mean age at surgery was 16.9 years (12 to 22). In all patients, the indication for surgery was knee pain and/or mechanical symptoms that were refractory to non-operative treatment. Three anatomical variations involving the distal femur were found in all knees: a deep femoral trochlea; a high A-shaped intercondylar notch; and a vertically oriented anterior cruciate ligament. The average trochlea sulcus angle measured 123°. Pathology included: synovial plica (one knee); chondral lesions (three knees); discoid lateral meniscus (11 knees); and meniscal tears (six knees). All patients were pain-free and returned to normal activity at final follow-up. CONCLUSION: Children with achondroplasia have characteristic distal femur anatomy noted during knee arthroscopy. These variations should be considered normal during knee arthroscopy in these patients. Arthroscopic findings confirmed previous MRI findings within this specific population with the addition of a deep trochlear groove which was not previously reported.