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Tropical forests face increasing climate risk1,2, yet our ability to predict their response to climate change is limited by poor understanding of their resistance to water stress. Although xylem embolism resistance thresholds (for example, [Formula: see text]50) and hydraulic safety margins (for example, HSM50) are important predictors of drought-induced mortality risk3-5, little is known about how these vary across Earth's largest tropical forest. Here, we present a pan-Amazon, fully standardized hydraulic traits dataset and use it to assess regional variation in drought sensitivity and hydraulic trait ability to predict species distributions and long-term forest biomass accumulation. Parameters [Formula: see text]50 and HSM50 vary markedly across the Amazon and are related to average long-term rainfall characteristics. Both [Formula: see text]50 and HSM50 influence the biogeographical distribution of Amazon tree species. However, HSM50 was the only significant predictor of observed decadal-scale changes in forest biomass. Old-growth forests with wide HSM50 are gaining more biomass than are low HSM50 forests. We propose that this may be associated with a growth-mortality trade-off whereby trees in forests consisting of fast-growing species take greater hydraulic risks and face greater mortality risk. Moreover, in regions of more pronounced climatic change, we find evidence that forests are losing biomass, suggesting that species in these regions may be operating beyond their hydraulic limits. Continued climate change is likely to further reduce HSM50 in the Amazon6,7, with strong implications for the Amazon carbon sink.
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Carbono , Florestas , Árvores , Clima Tropical , Biomassa , Carbono/metabolismo , Secas , Árvores/crescimento & desenvolvimento , Árvores/metabolismo , Xilema/metabolismo , Chuva , Mudança Climática , Sequestro de Carbono , Estresse Fisiológico , DesidrataçãoRESUMO
Mitochondrial cytopathies can have kidney involvement in up to half of cases. Their diagnosis is challenging due to phenotypic variability, lack of noninvasive tests to assess mitochondrial dysfunction and genetic heterogeneity. We report on a young adult male with hypertrophic cardiomyopathy (HCM) and chronic kidney disease (CKD) with sub-nephrotic proteinuria, who presented to the emergency department with kidney failure and hypervolemia requiring dialysis. A kidney biopsy showed focal segmental and global glomerulosclerosis, extensive foot process effacement, and abnormal mitochondria in podocytes and tubular epithelial cells; the genetic workup identified a rare FASTKD2 exon 2 variant, c.29G>C p.(Ser10Thr), in homozygosity; and functional mitochondrial assays in cultured skin fibroblasts showed reduction in FASTKD2 protein expression and moderate combined impairment in mitochondrial respiratory chain (MRC) assembly and function. This is the first report of a FASTKD2-associated cardiorenal mitochondrial cytopathy, characterized by young adult-onset proteinuric CKD and dilated HCM, in the absence of the severe neurologic manifestations described in patients with biallelic FASTKD2 mutations. We hypothesize that the increased production of reactive oxygen species associated with moderate MRC impairment could result in a smoldering podocytopathy with progressive proteinuric CKD, without overt tubulopathy or encephalomyopathy, which are, instead, pathogenically related to adenosine triphosphate deficiency.
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Fluid transport across intervessel pit membranes of angiosperm xylem plays a major role in plant transpiration, with transport resistance largely depending on pore constriction sizes. Traditionally, fluid particles traversing pit membranes are assumed to cross a single instead of multiple pore constrictions. We tested a multi-layered pit membrane model in xylem of eight angiosperm species by estimating the size frequency of pore constrictions in relation to pit membrane thickness and compared modelled data with perfusion characteristics of nanoscale gold particles based on transmission electron microscopy. The size frequency of modelled pore constrictions showed similar patterns to the measured number of perfused particle sizes inside pit membranes, although frequency values measured were 10-50 times below modelled data. Small particles enter pit membranes most easily, especially when injected in thin pit membranes. The trapping of gold particles by pore constrictions becomes more likely with increasing pore constriction number and pit membrane thickness. While quantitative differences between modelled and experimental data are due to various practical limitations, their qualitative agreement supports a multi-layered pit membrane model with multiple pore constrictions. Pore constrictions between 5 and 50 nm are realistic, and confirm the mesoporous nature of pit membranes.
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Ouro , Magnoliopsida , Xilema , Transporte Biológico , Perfusão , ÁguaRESUMO
Drought-induced xylem embolism is a primary cause of plant mortality. Although c. 70% of cycads are threatened by extinction and extant cycads diversified during a period of increasing aridification, the vulnerability of cycads to embolism spread has been overlooked. We quantified the vulnerability to drought-induced embolism, pressure-volume curves, in situ water potentials, and a suite of xylem anatomical traits of leaf pinnae and rachises for 20 cycad species. We tested whether anatomical traits were linked to hydraulic safety in cycads. Compared with other major vascular plant clades, cycads exhibited similar embolism resistance to angiosperms and pteridophytes but were more vulnerable to embolism than noncycad gymnosperms. All 20 cycads had both tracheids and vessels, the proportions of which were unrelated to embolism resistance. Only vessel pit membrane fraction was positively correlated to embolism resistance, contrary to angiosperms. Water potential at turgor loss was significantly correlated to embolism resistance among cycads. Our results show that cycads exhibit low resistance to xylem embolism and that xylem anatomical traits - particularly vessels - may influence embolism resistance together with tracheids. This study highlights the importance of understanding the mechanisms of drought resistance in evolutionarily unique and threatened lineages like the cycads.
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Cycadopsida , Secas , Folhas de Planta , Água , Xilema , Xilema/fisiologia , Xilema/anatomia & histologia , Folhas de Planta/anatomia & histologia , Folhas de Planta/fisiologia , Cycadopsida/fisiologia , Cycadopsida/anatomia & histologia , Especificidade da EspécieRESUMO
Understanding xylem embolism formation is challenging due to dynamic changes and multiphase interactions in conduits. Here, we hypothesise that embolism spread involves gas diffusion in xylem, and is affected by time. We measured hydraulic conductivity (Kh) in flow-centrifuge experiments over 1 h at a given pressure and temperature for stem samples of three angiosperm species. Temporal changes in Kh at 5, 22, and 35°C, and at various pressures were compared to modelled gas concentration changes in a recently embolised vessel in the centre of a centrifuge sample. Temporal changes in Kh were logarithmic and species-specific. Maximum relative increases of Kh between 6% and 40% happened at 22°C for low centrifugal speed (<3250 RPM), while maximum decreases between 41% and 61% occurred at higher speeds. These reductions in Kh were experimentally shown to be associated with a temporal increase of embolism at the centre of centrifuge samples, which was likely associated with gas concentration increases in recently embolized vessels. Although embolism is mostly pressure-driven, our experimental and modelled data indicate that time, conduit characteristics, and temperature are involved due to their potential role in gas diffusion. Gas diffusion, however, does not seem to cover the entire process of embolism spread.
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Embolism resistance of xylem tissue varies among species and is an important trait related to drought resistance, with anatomical attributes like pit membrane thickness playing an important role in avoiding embolism spread. Grafted Citrus trees are commonly grown in orchards, with the rootstock being able to affect the drought resistance of the whole plant. Here, we evaluated how rootstocks affect the vulnerability to embolism resistance of the scion using several rootstock/scion combinations. Scions of 'Tahiti' acid lime, 'Hamlin', 'Pera' and 'Valencia' oranges grafted on a 'Rangpur' lime rootstock exhibit similar vulnerability to embolism. In field-grown trees, measurements of leaf water potential did not suggest significant embolism formation during the dry season, while stomata of Citrus trees presented an isohydric response to declining water availability. When 'Valencia' orange scions were grafted on 'Rangpur' lime, 'IAC 1710' citrandarin, 'Sunki Tropical' mandarin or 'Swingle' citrumelo rootstocks, variation in intervessel pit membrane thickness of the scion was found. The 'Rangpur' lime rootstock, which is known for its drought resistance, induced thicker pit membranes in the scion, resulting in higher embolism resistance than the other rootstocks. Similarly, the rootstock 'IAC 1710' citrandarin generated increased embolism resistance of the scion, which is highly relevant for citriculture.
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Citrus , Raízes de Plantas , Xilema , Citrus/fisiologia , Xilema/fisiologia , Raízes de Plantas/fisiologia , Água/metabolismo , Secas , Folhas de Planta/fisiologia , Folhas de Planta/anatomia & histologia , Estômatos de Plantas/fisiologiaRESUMO
BACKGROUND AND AIMS: Lianas have higher relative abundance and biomass in drier seasonal forests than in rainforests, but whether this difference is associated with their hydraulic strategies is unclear. Here, we investigate whether lianas of seasonally dry forests are safer and more efficient in water transport than rainforest lianas, explaining patterns of liana abundance. METHODS: We measured hydraulic traits on five pairs of congeneric lianas of the tribe Bignonieae in two contrasting forest sites: the wet 'Dense Ombrophilous Forest' in Central Amazonia (~2 dry months) and the drier 'Semideciduous Seasonal Forest' in the inland Atlantic Forest (~6 dry months). We also gathered a broader database, including 197 trees and 58 liana species from different tropical forests, to compare hydraulic safety between habits and forest types. KEY RESULTS: Bignonieae lianas from both forests had high and similar hydraulic efficiency but exhibited variability in resistance to embolism across forest types when phylogenetic relationships were taken into account. Three genera had higher hydraulic safety in the seasonal forest than in the rainforest, but species across both forests had similar positive hydraulic safety margins despite lower predawn water potential values of seasonal forest lianas. We did not find the safety-efficiency trade-off. Merging our results with previously published data revealed a high variability of resistance to embolism in both trees and lianas, independent of forest types. CONCLUSIONS: The high hydraulic efficiency of lianas detected here probably favours their rapid growth across tropical forests, but differences in hydraulic safety highlight that some species are highly vulnerable and may rely on other mechanisms to cope with drought. Future research on the lethal dehydration threshold and the connection between hydraulic resistance strategies and liana abundance could offer further insights into tropical forest dynamics under climatic threats.
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Floresta Úmida , Estações do Ano , Clima Tropical , Florestas , Água/fisiologia , Bignoniaceae/fisiologia , Árvores/fisiologia , BrasilRESUMO
AIM: To investigate the effects of high-intensity interval training (HIIT) on periodontitis (PD) progression and behavioural outcomes. MATERIALS AND METHODS: Forty-eight Wistar rats were divided into four groups: non-trained (NT); non-trained with PD; HIIT with PD; and HIIT. The HIIT protocol, involving daily treadmill sessions, spanned 8 weeks, with PD induced by ligature after the 6th week. Behavioural tests were conducted to assess anxiety and memory. Post euthanasia, we evaluated the systemic inflammatory profile and oxidative stress markers in the hippocampus and amygdala. A morphological evaluation and elemental composition analysis of the mandibular alveolar bone were performed. RESULTS: PD exacerbated alveolar bone level, bone surface damage and alterations in calcium and phosphorus percentages on the bone surface (p < .05), while HIIT attenuated these changes (p < .05). HIIT improved systemic inflammatory markers altered by PD (tumour necrosis factor [TNF]-α, interleukin [IL]-10, TNF-α/IL-10 and IL-1ß/IL-10 ratios, p < .05). PD animals exhibited lower total antioxidant capacity and levels of thiobarbituric acid reactive substances in the amygdala and hippocampus, respectively (p < .05). HIIT maintained these parameters at levels similar to those in NT animals. HIIT improved anxiety and memory outcomes altered by PD (p < .05). CONCLUSIONS: HIIT attenuates systemic inflammation, anxiety and memory outcomes promoted by PD.
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Comportamento Animal , Treinamento Intervalado de Alta Intensidade , Periodontite , Condicionamento Físico Animal , Ratos Wistar , Animais , Treinamento Intervalado de Alta Intensidade/métodos , Ratos , Periodontite/terapia , Masculino , Estresse Oxidativo , Progressão da Doença , Hipocampo/metabolismo , Tonsila do Cerebelo/metabolismo , AnsiedadeRESUMO
Endocrine physiology is a complex subject for students. Game-based learning (GBL) and case-based learning (CBL) are active methodologies that are widely used because of their potential for motivation and greater proximity to the reality of modern students. We evaluated the effectiveness of GBL and CBL among veterinary medicine students compared with a control group using peer tutoring. Students (n = 106) from two institutions volunteered to participate in this study. The participants were submitted to a pretest questionnaire and subsequently were divided into three paired groups by their performance on the pretest exam: 1) traditional class + peer tutoring, 2) traditional class + GBL, and 3) traditional class + CBL. After the students completed the activities, their performance was once again evaluated by applying a new test with the same initial 10 questions and another set of 10 different questions. The students' perceptions and satisfaction with the methodologies and learning strategies were assessed. Anxiety was assessed with the State-Trait Anxiety Inventory before and after the conventional class and after the active methodologies. The GBL group significantly improved their correct answers compared with the baseline (P < 0.05), with no significant difference from CBL and peer tutoring. Anxiety levels did not differ regardless of the time of evaluation or the teaching methodology applied. GBL promoted a greater perception of the stimulus for self-study and problem-solving ability and contributed to the development of group dynamics compared with the group who received CBL (P < 0.05). In conclusion, GBL showed better results than peer tutoring and CBL.NEW & NOTEWORTHY We compared the supplementary use of game-based learning, case-based learning, and peer tutoring in the study of endocrine physiology by veterinary students and observed a slight advantage for game-based learning over the other two methodologies. The game was developed by the authors and is an unprecedented tool that can prove useful to improve knowledge acquisition in students of veterinary medicine. Thus, game-based learning is an effective supplementary teaching strategy.
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Aprendizagem , Estudantes , Humanos , Motivação , Resolução de Problemas , Inquéritos e QuestionáriosRESUMO
Intervessel pits are considered to function as valves that avoid embolism spreading and optimize efficient transport of xylem sap across neighbouring vessels. Hydraulic transport between vessels would therefore follow a safety-efficiency trade-off, which is directly related to the total intervessel pit area (Ap ), inversely related to the pit membrane thickness (TPM ) and driven by a pressure difference. To test this hypothesis, we modelled the relative transport rate of gas (ka ) and water (Q) at the intervessel pit level for 23 angiosperm species and correlated these parameters with the water potential at which 50% of embolism occurs (Ψ50 ). We also measured ka for 10 species using pneumatic measurements. The pressure difference across adjacent vessels and estimated values of ka and Q were related to Ψ50 , following a convex safety-efficiency trade-off based on modelled and experimental data. Minor changes in TPM and Ap exponentially affected the pressure difference and flow, respectively. Our results provide clear evidence that a xylem safety-efficiency trade-off is not linear, but convex due to flow across intervessel pit membranes, which represent mesoporous media within microporous conduits. Moreover, the convex nature of long-distance xylem transport may contribute to an adjustable fluid balance of plants, depending on environmental conditions.
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Embolia , Magnoliopsida , Plantas , Xilema , ÁguaRESUMO
Eating habits developed during childhood can be perpetuated along life and contribute to the emergence of disorders. We aimed to investigate the influence of distractors during experimental meals on the energy intake of children and adolescents. We followed the PRISMA guidelines and the study was registered in PROSPERO (CRD42021259946). The PICOS strategy consisted of children and adolescents (P), exposed to distractors during meals (I), compared with no distraction (C) and the outcome was energy intake (Kcal) (O) evaluated in crossover and parallel randomized clinical trials (RCTs) (S). Searches were conducted in PubMed, Scopus, Web of Science, Cochrane, Proquest, Embase, and LILACs databases. We employed RoB 2 tool and NutriGrade. Databases searches returned 9,576 references. Thirteen articles were selected (five crossover and eight parallel RCTs). Volunteers aged 3 to 17 years-old. All studies evaluated TV as distractor. Most studies presented high/moderate risk of bias. Meta-analysis of parallel RCT indicated no significant difference in energy intake while eating with TV (MD = 0.05; 95% CI -0.13 - 0.23, P = 0.57), with moderate certainty level. In conclusion, under laboratory conditions, eating with distractors seems to barely alter energy intake for children and adolescents.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2022.2055525 .
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Ingestão de Energia , Projetos de Pesquisa , Criança , Humanos , Adolescente , Pré-EscolarRESUMO
The suspension of social activities combined with health insecurity, uncertainty and fear of COVID-19 may influence physical activity practice. We aimed to investigate the relationship between the fear of COVID-19 and anxiety on physical activity patterns during the pandemic period. This cross-sectional study was performed in a sample of 520 Brazilian participants recruited by online sampling and snowball method. We assessed demographic variables, health perceptions, anxiety, fear of COVID-19 and physical activity characteristics. Both fear scores and anxiety were higher in woman (p < 0.0001). We observed a remarkable reduction in the frequency and intensity of physical activity and a modification in the exercise practice environment (from gym or sports centers to home-based physical activity) (p < 0.05). Sedentary (sitting) behavior increased during pandemic both in the weekdays and in the weekend (p < 0.0001). Participants who have never been infected were more prone of being classified in higher levels for physical activity (OR: 1.916, CI = 1.043-3.521) versus those who were previously infected (p = 0.05). Participants with a low or moderate level of physical activity before the pandemic presented lower chances of being classified as high physical activity level during the pandemic in comparison to those with high level before pandemic (p < 0.001). The Fear of Covid-19 score was negatively associated with the physical activity level (the higher the fear, the lower the level of physical activity); that is, for every increase in scale score, the odds of vigorous physical activity decreased 3%. In conclusion, fear of COVID-19 and previous contact with the virus negatively influenced physical activity practice.
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COVID-19 , Feminino , Humanos , Brasil/epidemiologia , Estudos Transversais , COVID-19/epidemiologia , Medo , Exercício FísicoRESUMO
In plants, xylem vessel length is important for long-distance water transport; however, the currently used methods for vessel length measurement are inconvenient and time-consuming. The recently developed semi-automated Pneumatron is a device based on the pneumatic theory that is similar to the air-injection method, and can rapidly estimate vessel length. Mean vessel length was compared between the Pneumatron and the air-injection method in seven woody species with a wide range of vessel lengths (2.3-78.7 cm). The results were consistent between the two methods, regardless of whether the same or different samples were used. The theory underlying the gas flow in vessels was improved and expanded, and compared to that underlying the water flow in order to better understand the pneumatic processes within a stem sample. Moreover, a new and simple equation for gas flow in vessels was derived based on the molar gas flow (mol s-1) rather than volume flow, because the former remains constant with distance throughout the stem axis. We strongly recommend using the Pneumatron in future studies owing to its low cost, convenience, rapidity, and simple operation. However, a number of potential issues need to be considered to avoid artifacts during measurements.
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Madeira , Xilema , Transporte Biológico , ÁguaRESUMO
Understanding how evolutionary history and the coordination between trait trade-off axes shape the drought tolerance of trees is crucial to predict forest dynamics under climate change. Here, we compiled traits related to drought tolerance and the fast-slow and stature-recruitment trade-off axes in 601 tropical woody species to explore their covariations and phylogenetic signals. We found that xylem resistance to embolism (P50) determines the risk of hydraulic failure, while the functional significance of leaf turgor loss point (TLP) relies on its coordination with water use strategies. P50 and TLP exhibit weak phylogenetic signals and substantial variation within genera. TLP is closely associated with the fast-slow trait axis: slow species maintain leaf functioning under higher water stress. P50 is associated with both the fast-slow and stature-recruitment trait axes: slow and small species exhibit more resistant xylem. Lower leaf phosphorus concentration is associated with more resistant xylem, which suggests a (nutrient and drought) stress-tolerance syndrome in the tropics. Overall, our results imply that (1) drought tolerance is under strong selective pressure in tropical forests, and TLP and P50 result from the repeated evolutionary adaptation of closely related taxa, and (2) drought tolerance is coordinated with the ecological strategies governing tropical forest demography. These findings provide a physiological basis to interpret the drought-induced shift toward slow-growing, smaller, denser-wooded trees observed in the tropics, with implications for forest restoration programmes.
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Secas , Xilema , Florestas , Filogenia , Folhas de Planta/fisiologia , Clima Tropical , MadeiraRESUMO
BACKGROUND: Abnormalities related to mineral and bone metabolism are a common finding in chronic kidney disease (CKD). Vitamin D compounds are often prescribed to CKD patients with the purpose to control secondary hyperparathyroidism and reduce the risk of high-turnover bone disease. However, data on the effect of vitamin D sterols on bone histology in non-dialysis CKD is limited. MATERIALS AND METHODS: A prospective controlled study was conducted on a cohort of 56 patients with CKD stages 3 and 4. 19 patients on calcitriol and 12 patients on cholecalciferol were compared to a group of 25 age- and sex-matched controls. Participants underwent a tetracycline double-labelled transiliac bone biopsy before starting therapy and again 12 months later. Changes from baseline in circulating biomarkers and bone histomorphometric parameters were analyzed. RESULTS: Low-turnover bone disease was the most common pattern of renal osteodystrophy on the initial biopsy. There was no difference in biochemical or histomorphometric values between the three study groups at baseline. Serum intact parathormone (iPTH) and bone formation rate decreased significantly in calcitriol-treated patients, with prevalence of low-turnover bone disease doubling from baseline. In contrast, no significant changes were noted in cholecalciferol-treated and control subjects. CONCLUSION: Calcitriol was effective in preventing secondary hyperparathyroidism and high-turnover bone disease. However, it was associated with an increased risk of developing or aggravating low-turnover bone disease. In the absence of a bone biopsy, calcitriol use in pre-dialysis CKD should be reserved for patients with a progressive rise in iPTH levels, in whom high-turnover bone disease is suspected.
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Distúrbio Mineral e Ósseo na Doença Renal Crônica , Hiperparatireoidismo Secundário , Insuficiência Renal Crônica , Vitamina D , Calcitriol , Colecalciferol , Distúrbio Mineral e Ósseo na Doença Renal Crônica/tratamento farmacológico , Distúrbio Mineral e Ósseo na Doença Renal Crônica/etiologia , Diálise/efeitos adversos , Humanos , Hiperparatireoidismo Secundário/tratamento farmacológico , Hiperparatireoidismo Secundário/etiologia , Hiperparatireoidismo Secundário/prevenção & controle , Hormônio Paratireóideo , Estudos Prospectivos , Diálise Renal/efeitos adversos , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/terapia , Esteróis/uso terapêutico , Vitamina D/uso terapêutico , VitaminasRESUMO
The COVID-19 pandemic caused several changes in the teaching-learning process, as it abruptly replaced the conventional classes into online classes despite social distancing requirements. Such changes may be associated with several mental health problems and negatively affect the quality of life and academic performance of university students. We performed a cluster analysis in a large sample of Brazilian undergraduate students, considering sociodemographic data, physical activity frequency, study areas, Burnout Syndrome (BS), Quality of Life (QoL) and perception of online learning (OL) during COVID-19 pandemic. Seven hundred and three students (between 17 and 62 years, from 67 higher education institutions) participated in the study. We identified three different profiles of students regarding psychological aspects and OL perception. The first profile, called as the 'Low QoL' group was composed of younger students, mainly females, with higher frequency of psychological disorders (as evidenced by the self-report of depression and/or anxiety), in addition to higher Burnout scores, lower QoL and worse OL perception. The second profile called 'Intermediate QoL' comprised participants with an average age of 45 years, with a greater number of men, married, with kids and working in addition to studying. They presented better OL scores than the 'Low QoL' group. The third profile called 'Better QoL' comprised students with higher scores in all domains of QoL and better OL perception, with greater frequency of physical activity and lower BS scores. Students from Health courses showed higher scores for general QoL, and also for the psychological and environmental domains in relation to the other areas. Besides, students of the Exact Sciences courses showed higher scores on all OL perception items in comparison to the other courses. Our results provide insights regarding the mental health profile of undergraduate students, allowing educational managers to outline specific coping strategies to assist students during the pandemic.
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COVID-19 , Educação a Distância , Esgotamento Psicológico/epidemiologia , COVID-19/epidemiologia , Análise por Conglomerados , Estudos Transversais , Exercício Físico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , Qualidade de Vida , SARS-CoV-2 , Estudantes , UniversidadesRESUMO
We aimed to validate a Brazilian Portuguese version of the Obsession with COVID-19 Scale (BP-OCS) using a large sample of university students in Brazil (N = 1454). The scale showed solid psychometric characteristics in terms of internal consistency (α = .78), test-retest reliability (ICC = .86), factorial validity (PAF and CFA support), and construct validity. Additionally, BP-OCS scores were found to be higher among females, participants with diagnosed depression, anxiety, and self-reported anxiety. These findings suggest that the BP-OCS is a reliable and valid measure of persistent and disturbed thinking about COVID-19 for Brazilian university students.
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COVID-19 , Brasil , COVID-19/diagnóstico , Feminino , Humanos , Idioma , Comportamento Obsessivo , Psicometria , Reprodutibilidade dos Testes , Inquéritos e Questionários , UniversidadesRESUMO
We investigated the fear of COVID-19 infection after proper translation and cultural adaptation of the "Fear of COVID-19 Scale" to the Brazilian Portuguese language. A sample of 1,743 Brazilian participants were included. The scale showed excellent psychometric characteristics. Women showed higher anxiety levels. Fear of COVID-19 scores were lower in males with occupational risk of contamination. On the other hand, women and younger individuals showed higher fear of COVID-19 infection scores. The Brazilian Fear of COVID-19 Scale proved to be a reliable tool with excellent psychometric properties for identifying fear of COVID-19 infection in the Brazilian population.
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COVID-19 , Brasil , Comparação Transcultural , Medo , Feminino , Humanos , Masculino , Psicometria , Reprodutibilidade dos Testes , SARS-CoV-2 , Inquéritos e QuestionáriosRESUMO
Embolism spreading in angiosperm xylem occurs via mesoporous pit membranes between vessels. Here, we investigate how the size of pore constrictions in pit membranes is related to pit membrane thickness and embolism resistance. Pit membranes were modelled as multiple layers to investigate how pit membrane thickness and the number of intervessel pits per vessel determine pore constriction sizes, the probability of encountering large pores, and embolism resistance. These estimations were complemented by measurements of pit membrane thickness, embolism resistance, and number of intervessel pits per vessel in stem xylem (n = 31, 31 and 20 species, respectively). The modelled constriction sizes in pit membranes decreased with increasing membrane thickness, explaining the measured relationship between pit membrane thickness and embolism resistance. The number of pits per vessel affected constriction size and embolism resistance much less than pit membrane thickness. Moreover, a strong relationship between modelled and measured embolism resistance was observed. Pore constrictions provide a mechanistic explanation for why pit membrane thickness determines embolism resistance, which suggests that hydraulic safety can be uncoupled from hydraulic efficiency. Although embolism spreading remains puzzling and encompasses more than pore constriction sizes, angiosperms are unlikely to have leaky pit membranes, which enables tensile transport of water.
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Embolia , Magnoliopsida , Constrição , Água , XilemaRESUMO
Embolism spreading in dehydrating angiosperm xylem is driven by gas movement between embolized and sap-filled conduits. Here we examine how the proximity to pre-existing embolism and hydraulic segmentation affect embolism propagation. Based on the optical method, we compare xylem embolism resistance between detached leaves and leaves attached to branches, and between intact leaves and leaves with cut minor veins, for six species. Embolism resistance of detached leaves was significantly lower than that of leaves attached to stems, except for two species, with all vessels ending in their petioles. Cutting of minor veins showed limited embolism spreading in minor veins near the cuts prior to major veins. Moreover, despite strong agreement in the overall embolism resistance of detached leaves between the optical and pneumatic method, minor differences were observed during early stages of embolism formation. We conclude that embolism resistance may represent a relative trait due to an open-xylem artefact, with embolism spreading possibly affected by the proximity and connectivity to pre-existing embolism as a gas source, while hydraulic segmentation prevents such artefact. Since embolism formation may not rely on a certain pressure difference threshold between functional and embolized conduits, we speculate that embolism is facilitated by pressure-driven gas diffusion across pit membranes.