Search

Abstract Planetary exploration relies considerably on mineral characterization to advance our understanding of the solar system, the planets and their evolution. Thus, we must understand past and present processes that can alter materials exposed on the surface, affecting space mission data. Here, we analyze the first dataset monitoring the evolution of a known mineral target in situ on the Martian surface, brought there as a SuperCam calibration target onboard the Perseverance rover. We used Raman spectroscopy to monitor the crystalline state of a synthetic apatite sample over the first 950 Martian days (sols) of the Mars2020 mission. We note significant variations in the Raman spectra acquired on this target, specifically a decrease in the relative contribution of the Raman signal to the total signal. These observations are consistent with the results of a UV-irradiation test performed in the laboratory under conditions mimicking ambient Martian conditions. We conclude that the observed evolution reflects an alteration of the material, specifically the creation of electronic defects, due to its exposure to the Martian environment and, in particular, UV irradiation. This ongoing process of alteration of the Martian surface needs to be taken into account for mineralogical space mission data analysis.

This work analyses and improves the distribution of the flow of flue gases along the inlet duct of two industrial Heat Recovery Steam Generation (HRSG) boilers. The inlet duct connection with the boiler casing presents a special configuration, being axial for one boiler and radial for the other. The study was carried out using a 3D Computational Fluid Dynamics (CFD) modelling. The flow uniformity improvement is studied considering the introduction of baffles, perforated plates and the Part Elimination and Lattice Search (PELS) method. The Root Mean Square (RMS) axial velocity is used to determine uniform flow distribution. Its value must be equal to or below 0.2 m/s. Nevertheless, the pressure drop in the boiler must not increase by 1 mbar as compared to the standard case. After analysing the 3D CFD modelling results, our conclusion is that, in an axial configuration, the PELS method and a perforated plate (TAD44A65) located at the inlet of the recovery zone can improve the fluid flow uniformity to 40 %. For the radial configuration, only a perforated plate (TAD44A65) located at the inlet of the recovery zone improves fluid flow uniformity to 43 %.

Abstract The SuperCam instrument onboard the Mars 2020 Perseverance rover investigates Martian geological targets by a combination of multiple spectroscopic techniques. As Raman, Visible‐Infrared Spectroscopy, and Laser‐Induced Breakdown Spectroscopy (LIBS) spectra deliver complementary information about the interrogated sample, the multivariate analysis of combined spectroscopic data sets is here proposed as a tool to optimize the SuperCam capability to discriminate mineral phases on Mars. For this purpose, the laboratory study of carbonate phases within the Ca‐Mg‐Fe ternary system were selected as representative case of study. After the characterization of model samples, the discrimination capability of mono analytical Raman, VISIR, and LIBS data sets was evaluated by applying a chemometric approach based on the combination of principal component analysis (for sample clustering) and Linear Discriminant Analysis (for mineral classification). Afterward, the low‐level combination (LL) of Raman, VISIR, and LIBS data was achieved by concatenating their spectra into a single data matrix. The mineral classification achieved by LL data sets outperformed the mono analytical ones, thus proving the complementarity between molecular and elemental spectroscopic techniques. Mineral classification was further improved by using a mid‐level data combination strategy. After evaluating benefits and limitations afforded by the proposed combination strategies, future developments are finally outlined. As such, the final objective of this research line is to develop a classification model based on data combination to optimize the capability of SuperCam in discriminating relevant minerals on Mars, this being a key requirement for the selection of the optimal targets to be cached for the future Mars Sample Return Mission.

In the present work, an improved phaseless approach to microwave imaging is presented. Starting from the Contrast Source formulation of the scattering problem, a single-step procedure with no intermediate phase-retrieval process is described. The reconstruction capabilities of the proposed phaseless inverse method are numerically validated by firstly considering simple dielectric targets. Then, a slice breast model with the inclusion of a cancerous portion is analyzed. The identification of different types of breast tissue is successfully achieved, thus confirming the validity and potentialities of the proposed phaseless technique in the framework of biomedical imaging.

Global warming is affecting biodiversity; however, the extent to which animal reproductive processes respond to predicted temperature increments remains largely unexplored. The thermal environment has a pronounced impact on metabolic rates of ectotherms; therefore, an interesting question to assess is whether temperature increase might affect specific reproductive mechanisms like sperm performance in ectotherms. Moreover, in many species, oviductal fluid (OF) is known to regulate and maintain sperm quality; however, the role of OF in relation to the effects of high temperature on sperm remains unclear. Our aim was to experimentally test the effect of increased temperature on sperm velocity, swimming path and percentage of motility in neutral conditions at ejaculation (without OF) and in female's reproductive tract fluid (with OF), in a social ectotherm lizard model, Tropidurus spinulosus, which has specific thermal requirements for reproduction. Our results suggest that a rising temperature associated with global warming (+4°C) affects negatively sperm dynamics and survival. However, OF ameliorated the harmful effects of high temperature. This is an important point, as this study is the first to have tested the role of OF in preserving sperm from a warmer pre-fertilization environment. These results contribute to our understanding of how thermal environment changes might affect post-copulatory reproductive mechanisms. This article has an associated First Person interview with the first author of the paper.

En Argentina no se han realizado estudios destinados a establecer la prevalencia de disglucemias (glucemia alterada en ayunas [GAA], tolerancia alterada a la glucosa [TAG] y diabetes mellitus [DM]) en pacientes con enfermedad renal. Se decidió realizar un estudio observacional, evaluando la frecuencia con prueba de tolerancia oral a glucosa (PTOG) en pacientes con enfermedad renal crónica (ERC), sin registro de disglucemia en sus historias clínicas. Se realizó PTOG a 254 pacientes (60,62% masculinos), con ERC estadios 3, 4 y 5, en tratamiento conservador, hemodiálisis o trasplante. Los resultados mostraron pacientes con valores de DM: 10 pacientes según ayunas exclusivamente (3,94%; IC 95%: 1,35-6,53%); exclusivamente segunda hora, 11 pacientes (4,33%; IC 95%: 1,63-7,03%); por ambos criterios, 15 pacientes (5,91%; IC 95%: 2,81-9,00%); por al menos un criterio, 36 pacientes (14,17%; IC 95%: 9,69-18,66%). En análisis multivariado, la DM se asoció con valor de cintura (OR = 1,033 por cm; IC 95%: 1,005-1,062; p = 0,019) y con tratamiento sustitutivo vs. conservador (OR = 0,41; IC 95%: 0,19-0,92; p = 0,028). La GAA (criterio ADA) fue del 19,75% en tratamiento conservador vs. 9,24% en tratamiento sustitutivo, con diferencia estadísticamente significativa. No fue significativa la diferencia de TAG que evidenció 24,6 y 20,3% en tratamiento conservador y sustitutivo, respectivamente. Se propone la realización de PTOG en todo paciente con ERC, ya que permite la detección de todo el rango de disglucemias desconocidas, evitando el subdiagnóstico y favoreciendo la realización de tratamientos para evitar su progresión, en caso de estar ante la presencia de un grupo de riesgo para DM (GAA o TAG), así como la elección de la medicación más adecuada para el trasplante o el inicio del tratamiento de nuevos casos de DM no diagnosticada, para disminuir la morbimortalidad.

With the energetic particle telescope (EPT) performing with direct electron and proton discrimination on board the ESA satellite PROBA-V, we analyze the high-resolution measurements of the charged particle radiation environment at an altitude of 820 km for the year 2015. On 17 March 2015, a big geomagnetic storm event injected unusual fluxes up to low radial distances in the radiation belts. EPT electron measurements show a deep dropout at L > 4 starting during the main phase of the storm, associated to the penetration of high energy fluxes at L < 2 completely filling the slot region. After 10 days, the formation of a new slot around L = 2.8 for electrons of 500–600 keV separates the outer belt from the belt extending at other longitudes than the South Atlantic Anomaly. Two other major events appeared in January and June 2015, again with injections of electrons in the inner belt, contrary to what was observed in 2013 and 2014. These observations open many perspectives to better understand the source and loss mechanisms, and particularly concerning the formation of three belts.

Objective: The present study examined the association between passive FB use and academic stress, as well as the moderating role of users' dispositional levels of authenticity. Participants and Methods: A total of 188 college students responded to questionnaires regarding their FB use, trait authenticity, and academic stress. Results: The amount of time users reported they routinely engaged in passive FB use significantly correlated with academic stress. Further, users' levels of trait authenticity moderated this relationship. Time spent passively using FB was positively associated with academic stress only when user authenticity was high. However, how often students passively use FB was not significantly associated with academic stress regardless of their authenticity levels. Conclusions: These findings suggest that using FB passively for longer time periods might be a way to avoid academic tasks, which in turn might be associated with greater academic stress for those students who report higher levels of authenticity.

Few studies have considered bilingualism's impact on cognitive development within the sociolinguistic and cultural context of the immigrant communities where bilingualism is commonly practiced. In the United States, many Mexican-origin bilingual youth practice their bilingual skills by "brokering" (i.e. translating/interpreting between languages) for their immigrant parents who have low English proficiency. Meanwhile, these youth may also experience discrimination in their daily life. The present study focuses on Mexican-origin bilingual youth brokers (N = 334) in order to examine how discriminatory experiences (i.e. daily and ethnic discrimination) and bilingual brokering experiences captured by profiles are related to cognitive control performance (i.e. attentional control and inhibition). We found no significant direct influence of either bilingual broker profiles or discriminatory experiences on cognitive control. However, the associations between discriminatory experiences and cognitive control performance depended upon brokering experiences. Specifically, greater discrimination was associated with lower cognitive control performance among moderate brokers (with moderate bilingual experiences), but the association was attenuated among efficacious brokers (with positive bilingual experiences). Findings highlight the need to consider the sociolinguistic heterogeneity of both discriminatory experiences and language use when investigating cognitive control performance in bilinguals.

Background and study aims: Bariatric endoscopy has emerged as an aid in the nonsurgical treatment of obesity. The objective of this study is to critically provide the results and follow-up of endoscopic sleeve gastroplasty 1 year after the procedure. Patients and methods: Prospective single-center follow-up study of 25 patients (5 men, 20 women) who underwent flexible endoscopic suturing for endoluminal gastric volume reduction. A multidisciplinary team provided post-procedure care. Patient outcomes were recorded at 1 year after the procedure. Linear regression analysis was done to evaluate the variables associated with best results at 1 year of follow-up. Results: Mean body mass index (BMI) was 38.5 ± 4.6 kg/m2 (range 30 – 47) and mean age 44.5 ± 8.2 years (range 29 – 60). At 1 year, 22 patients continued with the follow-up (2 dropped out at 6 months and 1 at 3 months). There were no major intra-procedural, early, or delayed adverse events. Mean BMI loss was 7.3 ± 4.2 kg/m2, and mean percentage of total body weight loss was 18.7 ± 10.7 at 1 year. In the linear regression analysis, adjusted by initial BMI, variables associated with %TBWL involved the frequency of nutritional (β = 0.563, P = 0.014) and psychological contacts (β = 0.727, P = 0.025). The number of nutritional and psychological contacts were predictive of good weight loss results. Conclusions: Endoscopic sleeve gastroplasty is a feasible, reproducible, and effective procedure to treat obesity. Nutritional and psychological interaction are predictive of success.

Aboveground tropical tree biomass and carbon storage estimates commonly ignore tree height (H). We estimate the effect of incorporating H on tropics-wide forest biomass estimates in 327 plots across four continents using 42 656 H and diameter measurements and harvested trees from 20 sites to answer the following questions: 1. What is the best H-model form and geographic unit to include in biomass models to minimise site-level uncertainty in estimates of destructive biomass? 2. To what extent does including H estimates derived in (1) reduce uncertainty in biomass estimates across all 327 plots? 3. What effect does accounting for H have on plot- and continental-scale forest biomass estimates? The mean relative error in biomass estimates of destructively harvested trees when including H (mean 0.06), was half that when excluding H (mean 0.13). Power- and Weibull-H models provided the greatest reduction in uncertainty, with regional Weibull-H models preferred because they reduce uncertainty in smaller-diameter classes (≤40 cm D) that store about one-third of biomass per hectare in most forests. Propagating the relationships from destructively harvested tree biomass to each of the 327 plots from across the tropics shows that including H reduces errors from 41.8 Mg ha−1 (range 6.6 to 112.4) to 8.0 Mg ha−1 (−2.5 to 23.0). For all plots, aboveground live biomass was −52.2 Mg ha−1 (−82.0 to −20.3 bootstrapped 95% CI), or 13%, lower when including H estimates, with the greatest relative reductions in estimated biomass in forests of the Brazilian Shield, east Africa, and Australia, and relatively little change in the Guiana Shield, central Africa and southeast Asia. Appreciably different stand structure was observed among regions across the tropical continents, with some storing significantly more biomass in small diameter stems, which affects selection of the best height models to reduce uncertainty and biomass reductions due to H. After accounting for variation in H, total biomass per hectare is greatest in Australia, the Guiana Shield, Asia, central and east Africa, and lowest in east-central Amazonia, W. Africa, W. Amazonia, and the Brazilian Shield (descending order). Thus, if tropical forests span 1668 million km2 and store 285 Pg C (estimate including H), then applying our regional relationships implies that carbon storage is overestimated by 35 Pg C (31–39 bootstrapped 95% CI) if H is ignored, assuming that the sampled plots are an unbiased statistical representation of all tropical forest in terms of biomass and height factors. Our results show that tree H is an important allometric factor that needs to be included in future forest biomass estimates to reduce error in estimates of tropical carbon stocks and emissions due to deforestation.

El establecimiento y monitoreo de parcelas permanentes en los trópicos es indispensable para entender la dinámica y biodiversidad de los bosques tropicales. La conformación de la Red Amazónica de Inventarios Forestales (RAINFOR) ha permitido estudiar el Amazonas a nivel regional y ha promovido el intercambio de información entre investigadores independientes. En esta revisión se presentan: a) los objetivos y lecciones aprendidas por la red RAINFOR; b) la importancia de ForestPlots.net como herramienta de apoyo para una red de parcelas forestales; y c) algunos de los principales descubrimientos científicos generados por RAINFOR. RAINFOR es una red científica que en los últimos diez años ha colectado, organizado y analizado datos de más de 200 parcelas forestales. Las mediciones diamétricas y la información taxonómica se guardan y manejan en la base de datos ForestPlots.net. Algunos de los principales descubrimientos de RAINFOR incluyen: 1) el incremento en biomasa en el Amazonas; 2) la diferencia en las tasas de recambio y biomasa entre la región Occidente y los bosques del Centro-Este; 3) cambios a largo plazo en la densidad de lianas, e incrementos en la mortalidad a corto plazo en respuesta a la sequía. Dada la importancia del Amazonas, debido a su gran diversidad y su contribución al ciclo global de carbono, es necesario continuar con proyectos de investigación que permitan entender su repuesta a los cambios ambientales.

Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical countries. Utilising this database, our objectives were: 1. to determine if H:D relationships differ by geographic region and forest type (wet to dry forests, including zones of tension where forest and savanna overlap). 2. to ascertain if the H:D relationship is modulated by climate and/or forest structural characteristics (e.g. stand-level basal area, A). 3. to develop H:D allometric equations and evaluate biases to reduce error in future local-to-global estimates of tropical forest biomass. Annual precipitation coefficient of variation (PV), dry season length (SD), and mean annual air temperature (TA) emerged as key drivers of variation in H:D relationships at the pantropical and region scales. Vegetation structure also played a role with trees in forests of a high A being, on average, taller at any given D. After the effects of environment and forest structure are taken into account, two main regional groups can be identified. Forests in Asia, Africa and the Guyana Shield all have, on average, similar H:D relationships, but with trees in the forests of much of the Amazon Basin and tropical Australia typically being shorter at any given D than their counterparts elsewhere. The region-environment-structure model with the lowest Akaike's information criterion and lowest deviation estimated stand-level H across all plots to within amedian −2.7 to 0.9% of the true value. Some of the plot-to-plot variability in H:D relationships not accounted for by this model could be attributed to variations in soil physical conditions. Other things being equal, trees tend to be more slender in the absence of soil physical constraints, especially at smaller D. Pantropical and continental-level models provided less robust estimates of H, especially when the roles of climate and stand structure in modulating H:D allometry were not simultaneously taken into account.

We analysed 1040 individual trees, located in 62 plots across the Amazon Basin for leaf mass per unit area (MA), foliar carbon isotopic composition (δ13C) and leaf level concentrations of C, N, P, Ca, Mg, K and Al. All trees were identified to the species level with the dataset containing 58 families, 236 genera and 508 species, distributed across a wide range of soil types and precipitation regimes. Some foliar characteristics such as MA, [C], [N] and [Mg] emerge as highly constrained by the taxonomic affiliation of tree species, but with others such as [P], [K], [Ca] and δ13C also strongly influenced by site growing conditions. By removing the environmental contribution to trait variation, we find that intrinsic values of most trait pairs coordinate, although different species (characterised by different trait suites) are found at discrete locations along a common axis of coordination. Species that tend to occupy higher fertility soils are characterised by a lower MA and have a higher intrinsic [N], [P], [K], [Mg] and δ13C than their lower fertility counterparts. Despite this consistency, different scaling patterns were observed between low and high fertility sites. Inter-relationships are thus substantially modified by growth environment. Analysing the environmental component of trait variation, we found soil fertility to be the most important predictor, influencing all leaf nutrient concentrations and δ13C and reducing MA. Mean annual temperature was negatively associated with leaf level [N], [P] and [K] concentrations. Total annual precipitation positively influences MA, [C] and δ13C, but with a negative impact on [Mg]. These results provide a first basis for understanding the relationship between the physiological functioning and distribution of tree species across Amazonia.

The Amazon basin, one of the most substantial biomass carbon pools on earth, is characterised by strong macroecological gradients in biomass, mortality rates, and wood density from west to east. These gradients could affect necromass stocks, but this has not yet been tested. This study aims to assess the stocks and determinants of necromass across Amazonian forests. Field-based and literature data were used to find relationships between necromass and possible determinants. Furthermore, a simple model was applied to estimate and extrapolate necromass stocks across terra firma Amazonian forests. In eight northwestern and three northeastern Amazonian permanent plots, volumes of coarse woody debris (≥10 cm diameter) were measured in the field and the density of each decay class was estimated. Forest structure and historical mortality data were used to determine the factors controlling necromass. Necromass is greater in forests with low stem mortality rates (northeast) rather than in forests with high stem mortality rates (northwest) (58.5±10.6 and 27.3±3.2 Mg ha−1, respectively). Using all published necromass values, we find that necromass across terra firma forests in Amazonia is positively related to both forest dynamics (mortality mass inputs and a surrogate for decomposition rate (average wood density of living trees)) and forest structure (biomass), but is better explained by forest dynamics. We propose an improved method to estimate necromass for plots where necromass has not been measured. The estimates, together with other actual measurements of necromass, were scaled-up to project a total Amazonian necromass of 9.6±1.0 Pg C. The ratio of necromass (on average weighted by forest region) to coarse aboveground biomass is 0.127. Overall, we find (1) a strong spatial trend in necromass in parallel with other macroecological gradients and (2) that necromass is a substantial component of the carbon pool in the Amazon.

Leaf size influences many aspects of tree function such as rates of transpiration and photosynthesis and, consequently, often varies in a predictable way in response to environmental gradients. The recent development of pan-Amazonian databases based on permanent botanical plots has now made it possible to assess trends in leaf size across environmental gradients in Amazonia. Previous plot-based studies have shown that the community structure of Amazonian trees breaks down into at least two major ecological gradients corresponding with variations in soil fertility (decreasing from southwest to northeast) and length of the dry season (increasing from northwest to south and east). Here we describe the geographic distribution of leaf size categories based on 121 plots distributed across eight South American countries. We find that the Amazon forest is predominantly populated by tree species and individuals in the mesophyll size class (20.25–182.25 cm2). The geographic distribution of species and individuals with large leaves (>20.25 cm2) is complex but is generally characterized by a higher proportion of such trees in the northwest of the region. Spatially corrected regressions reveal weak correlations between the proportion of large-leaved species and metrics of water availability. We also find a significant negative relationship between leaf size and wood density.

The effect of temperature in the catalytic cracking of HDPE over a spent FCC catalyst on the product distribution has been studied using a two-step reaction system. Thermal pyrolysis of HDPE has been carried out in a conical spouted bed reactor and the volatiles formed (mainly waxes) have been fed in-line into a catalytic fixed bed reactor. An increase in the second stage temperature from 450 °C to 550 °C gives way to an enhancement of cracking reactions, achieving full conversion of waxes at 550 °C. At this temperature, gasoline and light olefins are the main product fractions obtained, with a yield of 52 wt% and 28 wt%, respectively.

Attendances to provincial emergency centres involving penetrating sharp trauma are a frequent occurrence and represent a significant burden on a department’s workload. The majority of studies in this area have been based in major urban hospitals. This is an observational study of patients attending Stanger Hospital Emergency Centre in the rural district of Ilembe with penetrating sharp trauma. Method: Notes collected from a two-month period in 2011 were reviewed and data collected to determine patient characteristics, wounds inflicted, distribution of injury and patient outcome. Results: 127 case notes were analysed. The majority of patients were young (median age 27 years), male (108/127; 85%), and had reportedly ingested alcohol (84/127; 66.1%). Most had more than one wound (median 2 wounds per patient) but did not suffer from significant blood loss and there were no deaths. Only 15/127 (11.8%) required hospital admission. Discussion: Most patients suffered multiple wounds over multiple sites but these did not frequently require admission to hospital and caused no deaths. As long as clinicians remain vigilant for more severe injuries, these patients can generally be treated in low resourced environments. The majority of patients were discharged directly from the Emergency Centre making it the best place for these people to receive health education to prevent further injuries.

A commercial FCC catalyst based on a zeolite active phase has been used to perform the valorisation of waste tires by in situ catalytic pyrolysis. The process has been carried out in a conical spouted bed reactor provided by a continuous feeding system. The catalyst has been subjected to a steaming treatment in order to maximize diesel fraction. High diesel (50.5 wt %) and char (35 wt %) yields are obtained, together with low gas (0.6 wt %) and gasoline (13.9 wt %) fractions. The obtained liquid is highly aromatic, which is formed at the expense of the non-aromatic gasoline fraction.

The production of activated carbons derived from waste tires has been carried out using steam and carbon dioxide as activation agents. The effect of temperature and activation time over the carbons prepared has been studied. The material subjected to activation has been char or residual carbon black obtained by continuous flash pyrolysis of waste tires carried out in a conical spouted bed reactor at 500 °C. The activation has been carried out at 850 and 900 °C using steam and only at 900 °C using carbon dioxide due to the slower kinetics of this process. The activation runs have been conducted in a fixed bed reactor. An essentially mesoporous structure is developed in the process, with BET surface areas above 500 m2/g for the carbons obtained with steam and above 370 m2/g in those obtained using carbon dioxide.

Abstract preview not available - see full-text PDF article.