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"Alvarado, A."
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Robot rampage!
Donatello builds a robot to help fight evil, but when it malfunctions, the Teenage Mutant Ninja Turtles have a technological terror to battle.
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Unexpected long-range transport of glyoxal and formaldehyde observed from the Copernicus Sentinel-5 Precursor satellite during the 2018 Canadian wildfires
Glyoxal (CHOCHO) and formaldehyde (HCHO) are intermediate products in the tropospheric oxidation of the majority of volatile organic compounds (VOCs). CHOCHO is also a precursor of secondary organic aerosol (SOA) in the atmosphere. CHOCHO and HCHO are released from biogenic, anthropogenic, and pyrogenic sources. CHOCHO and HCHO tropospheric lifetimes are typically considered to be short during the daytime at mid-latitudes (e.g. several hours), as they are rapidly removed from the atmosphere by their photolysis, oxidation by OH, and uptake on particles or deposition. At night and at high latitudes, tropospheric lifetimes increase to many hours or even days. Previous studies demonstrated that CHOCHO and HCHO vertical column densities (VCDs) are well retrieved from space-borne observations using differential optical absorption spectroscopy (DOAS). In this study, we present CHOCHO and HCHO VCDs retrieved from measurements by TROPOMI (TROPOspheric Monitoring Instrument), launched on the Sentinel-5 Precursor (S5P) platform in October 2017. We observe strongly elevated amounts of CHOCHO and HCHO during the 2018 fire season in British Columbia, Canada, where a large number of fires occurred in August. CHOCHO and HCHO plumes from individual fire hot spots are observed in air masses travelling over distances of up to 1500 km, i.e. much longer than expected for the relatively short tropospheric lifetime expected for CHOCHO and HCHO. Comparison with simulations by the particle dispersion model FLEXPART (FLEXible PARTicle dispersion model) indicates that effective lifetimes of 20 h and more are needed to explain the observations of CHOCHO and HCHO if they decay in an effective first-order process. FLEXPART used in the study calculates accurately the transport. In addition an exponential decay, in our case assumed to be photochemical, of a species along the trajectory is added. We have used this simple approach to test our assumption that CHOCHO and HCHO are created in the fires and then decay at a constant rate in the plume as it is transported. This is clearly not the case and we infer that CHOCHO and HCHO are either efficiently recycled during transport or continuously formed from the oxidation of longer-lived precursors present in the plume, or possibly a mixture of both. We consider the best explanation of the observed CHOCHO and HCHO VCD in the plumes of the fire is that they are produced by oxidation of longer-lived precursors, which were also released by the fire and present in the plume.
Journal Article
Design, Materials, and Mechanobiology of Biodegradable Scaffolds for Bone Tissue Engineering
A review about design, manufacture, and mechanobiology of biodegradable scaffolds for bone tissue engineering is given. First, fundamental aspects about bone tissue engineering and considerations related to scaffold design are established. Second, issues related to scaffold biomaterials and manufacturing processes are discussed. Finally, mechanobiology of bone tissue and computational models developed for simulating how bone healing occurs inside a scaffold are described.
Journal Article
A quinary WTaCrVHf nanocrystalline refractory high-entropy alloy withholding extreme irradiation environments
In the quest of new materials that can withstand severe irradiation and mechanical extremes for advanced applications (
e.g
. fission & fusion reactors, space applications, etc.), design, prediction and control of advanced materials beyond current material designs become paramount. Here, through a combined experimental and simulation methodology, we design a nanocrystalline refractory high entropy alloy (RHEA) system. Compositions assessed under extreme environments and in situ electron-microscopy reveal both high thermal stability and radiation resistance. We observe grain refinement under heavy ion irradiation and resistance to dual-beam irradiation and helium implantation in the form of low defect generation and evolution, as well as no detectable grain growth. The experimental and modeling results—showing a good agreement—can be applied to design and rapidly assess other alloys subjected to extreme environmental conditions.
Refractory high entropy alloys (RHEAs) have recently been developed in the context of high-temperature and severe environmental applications. Here the authors, by combining simulation and experiments, develop an irradiation resistant, thermally stable, and strong RHEA for nuclear application.
Journal Article
Outcomes of Robotic-Assisted Bariatric Surgery Compared to Standard Laparoscopic Approach Using a Standardized Definition: First Look at the 2020 Metabolic and Bariatric Surgery Accreditation Quality Improvement Project (MBSAQIP) Data
PurposeThe primary objective of this study is to evaluate the outcomes of robotic-assisted (RA-) approach compared to the standard laparoscopic (L-) approach using the 2020 Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) registry Public Use File (PUF). Our secondary objective is to establish standards for the reporting of outcomes using PUF.Materials and MethodsUsing the PUF database (n = 168,568), patients were divided into sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), revisions, and conversions and then analyzed separately. We created balanced covariate through propensity score matching and inverse probability treatment weighting (IPTW). We also conducted multivariable relative risk regression to confirm our results.ResultsFor RYGB, the incidence of “transfusion” was significantly lower in the RA-RYGB compared to the L-RYGB. There was no significant difference in the rate of Serious Event Occurrences (SEOs) or rate of intervention at 30 days. For SG, there was a higher rate of “transfusion” in the RA group. Incidence of SEOs was also significantly higher in the RA-group. There was no significant difference in SEOs for conversions; however, revisions had a trend toward a lower rate of SEOs favoring the robotic approach. Operative times were significantly higher for all RA-groups.ConclusionRA- approach in metabolic and bariatric surgery (MBS) remains controversial because of differences in outcomes. The use of SEOs as reported by MBSAQIP in its semi-annual report can be used as a composite score to assess outcomes while using PUF. Further studies are needed to compare RA- to L- MBS.
Journal Article
Measurement report: Combined use of MAX-DOAS and AERONET ground-based measurements in Montevideo, Uruguay, for the detection of distant biomass burning
Biomass burning releases large amounts of aerosols and chemical species into the atmosphere, representing a major source of air pollutants. Emissions and by-products can be transported over long distances, presenting challenges in quantification. This is mainly done using satellites, which offer global coverage and data acquisition for places that are difficult to access. In this study, ground-based observations are used to assess the abundance of trace gases and aerosols. On 24 November 2020, a significant increase in formaldehyde was observed with a Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument located in Montevideo (Uruguay), and its vertical column densities reached values of 2.4×1016 molec. cm−2, more than twice the values observed during the previous days. This was accompanied by an increase in the aerosol levels measured by an AErosol RObotic NETwork (AERONET) photometer located at the same site. The aerosol optical depth (AOD) at 440 nm reached values close to 1, an order of magnitude larger than typical values in Montevideo. Our findings indicate that the increase was associated with the passage of a plume originating from distant biomass burning. This conclusion is supported by TROPOspheric Monitoring Instrument (TROPOMI) satellite observations as well as HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) simulations. The profiles of the gases and aerosols retrieved from the MAX-DOAS observations are consistent with the HYSPLIT analysis, showing the passage of a plume over Montevideo on 24 November located at a height of ∼ 1.5 km. This corroborates the finding that biomass burning events occurring about 800 km north of Montevideo can affect the local atmosphere through long-distance emissions transport. This study underscores the potential of ground-based atmospheric monitoring as a tool for detection of such events. Furthermore, it demonstrates greater sensitivity compared to satellite when it comes to detection of relatively small amounts of carbonyls like glyoxal and formaldehyde.
Journal Article
Age‐Dependent Differences in Cerebellar CB1 Receptor Expression and Its Association With Impulsivity and Alcohol Intake in Rats
The cannabinoid receptor 1 (CB1R) in the hippocampus has been involved in impulsivity and alcohol consumption in adolescent rats. However, the role of CB1R in the cerebellum, despite that structure's exceptionally high CB1R density, remains unexplored. We therefore tested the hypothesis that cerebellar CB1R contributes to regulating impulsive behaviour, alcohol consumption and seeking. Male Wistar rats, adolescent (PND25), adult (PND90) and aged (PND365), were assessed on the delay discounting task (DDT) and for voluntary alcohol intake‐conditioned place preference (ACPP). CB1R levels were quantified via immunofluorescence in the CRUS II and interposed nucleus. Separate cohorts were used for voluntary alcohol consumption and alcohol‐conditioned place preference (ACPP). Results showed that adolescent rats displayed significantly greater impulsivity and alcohol consumption than adults and aged rats, and only adolescents developed ACPP. CB1R expression peaked in adolescents across both cerebellar regions, but only Crus II levels correlated positively with impulsivity (k value), indicating a region‐ and age‐specific contribution. These data reveal, for the first time, that CB1R in cerebellar Crus II selectively underpins adolescent impulsive choice and alcohol consumption and seeking, highlighting both a novel brain locus and a critical developmental window for endocannabinoid modulation. Adolescent rats exhibited significantly higher levels of impulsivity compared to their adult and aged counterparts, and only adolescents developed alcohol‐conditioned place preference. CB1R expression in Crus II was notably higher in adolescents, which correlated with major impulsive behaviour. Together, these results emphasize the cerebellum's essential role in behavioural regulation.
Journal Article
Motion of continental slivers and creeping subduction in the northern Andes
Regions of intense continental deformation, termed continental slivers, have been identified in Chile, Bolivia and Ecuador. Analyses of GPS data now identify another large sliver in Peru, the Inca Sliver, that is moving away from a neighbouring sliver in Ecuador—implying that moving continental slivers control the deformation of almost the entire Andean mountain range.
Along the western margin of South America, plate convergence is accommodated by slip on the subduction interface and deformation of the overriding continent
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, continental deformation occurs mostly through the motion of discrete domains, hundreds to thousands of kilometres in scale. These continental slivers are wedged between the Nazca and stable South American plates. Here we use geodetic data to identify another large continental sliver in Peru that is about 300–400 km wide and 1,500 km long, which we call the Inca Sliver. We show that movement of the slivers parallel to the subduction trench is controlled by the obliquity of plate convergence and is linked to prominent features of the Andes Mountains. For example, the Altiplano is located at the boundary of converging slivers at the concave bend of the central Andes, and the extending Gulf of Guayaquil is located at the boundary of diverging slivers at the convex bend of the northern Andes. Motion of a few large continental slivers therefore controls the present-day deformation of nearly the entire Andes mountain range. We also show that a 1,000-km-long section of the plate interface in northern Peru and southern Ecuador slips predominantly aseismically, a behaviour that contrasts with the highly seismic neighbouring segments. The primary characteristics of this low-coupled segment are shared by
∼
20% of the subduction zones in the eastern Pacific Rim.
Journal Article
Rheological Evaluation of Ultra-High-Performance Concrete as a Rehabilitation Alternative for Pavement Overlays
This study evaluates the rheological behavior and mechanical performance of Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRC) mixes with varying superplasticizer dosages, aiming to optimize their use in pavement rehabilitation overlays on sloped surfaces. A reference self-compacting UHPFRC mix was modified by reducing the superplasticizer-to-binder ratio in incremental steps, and the resulting mixes were assessed through rheometry, mini-Slump, and Abrams cone tests. Key rheological parameters—static and dynamic yield stress, plastic viscosity, and thixotropy—were determined using the modified Bingham model. The results showed that reducing superplasticizer content increased yield stress and viscosity, enhancing thixotropic behavior while maintaining ultra-high compressive (≥130 MPa) and flexural strength (≥20 MPa) at 28 days. A predictive model was validated to estimate the critical yield stress needed for overlays on slopes. Among the evaluated formulations, the SP-2 mix met the stability and performance criteria and was successfully tested in a prototype overlay, demonstrating its viability for field application. This research confirms the potential of rheology-tailored UHPFRC as a high-performance solution for durable and stable pavement overlays in demanding geometric conditions.
Journal Article
The organization of semantic associations between senses in language
Distributional semantic representations were used to investigate crossmodal correspondences within language, offering a comprehensive analysis of how sensory experiences interconnect in linguistic constructs. By computing semantic proximity between words from different sensory modalities, a crossmodal semantic network was constructed, providing a general view of crossmodal correspondences in the English language. Community detection techniques were applied to unveil domains of experience where crossmodal correspondences were likely to manifest, while also considering the role of affective dimensions in shaping these domains. The study revealed the existence of an architecture of structured domains of experience in language, whereby crossmodal correspondences are deeply embedded. The present research highlights the roles of emotion and statistical associations in the organization of sensory concepts across modalities in language. The domains identified, including food, the body, the physical world and emotions/values, underscored the intricate interplay between the senses, emotion and semantic patterns. These findings align with the embodied lexicon hypothesis and the semantic coding hypothesis, emphasizing the capacity of language to capture and reflect crossmodal correspondences’ emotional and perceptual subtleties in the form of networks, while also revealing opportunities for further perceptual research on crossmodal correspondences and multisensory integration.
Journal Article