The objective of this study is to analyse the impact of perceived risk on intention to travel in the Covid-19 pandemic situation. Applying the Theory of Planned Behaviour, the study addresses the ...modulating effects of risk on the antecedents of intention; additionally, the resulting model includes the impact of this intention on the willingness to pay (WTP) more to benefit from additional safety measures at the destination. Furthermore, this paper addresses respondents belonging to an at-risk group for Covid-19 as a source of heterogeneity that may exert an effect on the results of the model. The model is tested using PLS-SEM, and the empirical results can contribute to the development of safety measures in tourism services and the design of effective actions to restore tourism.
Summary
Antibiotic pollution of non‐clinical environments might have a relevant impact on human health if resistant pathogens are selected. However, this potential risk is often overlooked, since ...drug concentrations in nature are usually below their minimal inhibitory concentrations (MICs). Albeit, antibiotic resistant bacteria can be selected even at sub‐MIC concentrations, in a range known as the sub‐MIC selective window. Using short‐term evolution experiments, we have determined the sub‐MIC selective windows of the opportunistic pathogen Pseudomonas aeruginosa for seven antibiotics of clinical relevance, finding the ones of quinolones to be the widest, and the ones of polymyxin B and imipenem, the narrowest. Clinically relevant multidrug‐resistant mutants arose within the sub‐MIC selective windows of most antibiotics tested, being some of these phenotypes mediated by efflux pumps' activity. The fact that the concentration of antibiotics reported in aquatic ecosystems – colonizable by P. aeruginosa – are, in occasions, higher than the ones that select multidrug‐resistant mutants in our assays, has implications for understanding the role of different ecosystems and conditions in the emergence of antibiotic resistance from a One‐Health perspective. Further, it reinforces the importance of procuring accurate information on the sub‐MIC selective windows for drugs of clinical value in pathogens with environmental niches.
ABSTRACT
The mechanisms of drought resistance that allow plants to successfully establish at different stages of secondary succession in tropical dry forests are not well understood. We characterized ...mechanisms of drought resistance in early and late‐successional species and tested whether risk of drought differs across sites at different successional stages, and whether early and late‐successional species differ in resistance to experimentally imposed soil drought. The microenvironment in early successional sites was warmer and drier than in mature forest. Nevertheless, successional groups did not differ in resistance to soil drought. Late‐successional species resisted drought through two independent mechanisms: high resistance of xylem to embolism, or reliance on high stem water storage capacity. High sapwood water reserves delayed the effects of soil drying by transiently decoupling plant and soil water status. Resistance to soil drought resulted from the interplay between variations in xylem vulnerability to embolism, reliance on sapwood water reserves and leaf area reduction, leading to a tradeoff of avoidance against tolerance of soil drought, along which successional groups were not differentiated. Overall, our data suggest that ranking species' performance under soil drought based solely on xylem resistance to embolism may be misleading, especially for species with high sapwood water storage capacity.
In this study we characterized patterns of variation in the resistance to soil drought among tropical dry forest tree seedlings, and tested whether risk of drought differs across sites of different successional stages and whether early and late‐successional species differ in resistance to experimentally imposed soil drought. Although early successional sites were warmer and drier than mature forest, early and late‐successional species did not differ in their resistance to soil drought, indicating multiple strategies within each group for coping with drought. We detected broad variation in resistance to soil drought among species and a trade‐off between xylem resistance to embolism and leaf loss, apparently mediated by variation in sapwood water storage capacity; high sapwood water storage capacity seemed to uncouple seedling water status from that of the soil during several weeks of soil drying. Overall, resistance to soil drought of a given species resulted from the interplay between variation in xylem vulnerability to embolism, reliance on sapwood water reserves and leaf area reduction.
The two major mechanisms of plant defense against pathogens are resistance (the host's ability to limit pathogen multiplication) and tolerance (the host's ability to reduce the effect of infection on ...its fitness regardless of the level of pathogen multiplication). There is abundant literature on virtually every aspect of plant resistance to pathogens. Although tolerance to plant pathogens is comparatively less understood, studies on this plant defense strategy have led to major insights into its evolution, mechanistic basis and genetic determinants. This review aims at summarizing current theories and experimental evidence on the evolutionary causes and consequences of plant tolerance to pathogens, as well as the existing knowledge on the genetic determinants and mechanisms of tolerance. Our review reveals that (i) in plant-pathogen systems, resistance and tolerance generally coexist, i.e., are not mutually exclusive; (ii) evidence of tolerance polymorphisms is abundant regardless of the pathogen considered; (iii) tolerance is an efficient strategy to reduce the damage on the infected host; and (iv) there is no evidence that tolerance results in increased pathogen multiplication. Taken together, the work discussed in this review indicates that tolerance may be as important as resistance in determining the dynamics of plant-pathogen interactions. Several aspects of plant tolerance to pathogens that still remain unclear and which should be explored in the future, are also outlined.
The acute impact of different types of physical activity on glycemic control in type 1 diabetes has not been well quantified.
Our objective was to estimate the rate of change (RoC) in glucose ...concentration induced acutely during the performance of structured exercise and at recovery in subjects with type 1 diabetes.
We searched for original articles in the PubMed, MEDLINE, Scopus, and Cochrane databases. Search terms included type 1 diabetes, blood glucose, physical activity, and exercise. Eligible studies (randomized controlled trials and non-randomized experiments) encompassed controlled physical activity sessions (continuous moderate CONT, intermittent high intensity IHE, resistance RESIST, and/or a resting reference REST) and reported excursions in glucose concentration during exercise and after its cessation. Data were extracted by graph digitization to compute two RoC measures from population profiles: RoCE during exercise and RoCR in recovery.
Ten eligible studies were found from 540 publications. Meta-analyses of exercise modalities versus rest yielded the following: RoCE -4.43 mmol/L h(-1) (p < 0.00001, 95% confidence interval CI -6.06 to -2.79) and RoCR +0.70 mmol/L h(-1) (p = 0.46, 95% CI -1.14 to +2.54) for CONT vs. REST; RoCE -5.25 mmol/L·h(-1) (p < 0.00001, 95 % CI -7.02 to -3.48) and RoCR +0.72 mmol/L h(-1) (p = 0.71, 95% CI -3.10 to +4.54) for IHE vs. REST; RoCE -2.61 mmol/L h(-1) (p = 0.30, 95% CI -7.55 to +2.34) and RoCR -0.02 mmol/L h(-1) (p = 1.00, 95% CI -7.58 to +7.53) for RESIST vs. REST.
Novel RoC magnitudes RoCE, RoCR reflected rapid decays of glycemia during CONT exercise and gradual recoveries immediately afterwards. RESIST showed more constrained decays, whereas discrepancies were found for IHE.
On the behaviour of raindrop fall speed due to wind Montero‐Martínez, Guillermo; García‐García, Fernando
Quarterly journal of the Royal Meteorological Society,
July 2016 Part A, 2016-07-00, 20160701, Letnik:
142, Številka:
698
Journal Article
Recenzirano
Measurements of raindrop fall speed gathered at the ground over several years are presented and analysed in view of the horizontal wind intensity during sampling. It is confirmed that super‐terminal ...drops occur only for diameters less than about 0.7 mm and that their percentage numbers increase during windy periods. Furthermore, through statistical and post hoc data analyses, it is shown that wind affects the fall speed of individual raindrops. A remarkable feature is the detection of sub‐terminal raindrops, i.e. those having slower fall speeds than their calculated terminal velocities, smaller than 2 mm. Evidence that wind affects raindrop behaviour includes observations showing that under windy conditions: (i) super‐terminal drops exhibit larger fall speed departures from the expected terminal speeds than in calm wind periods; and (ii) the percentage number of sub‐terminal drops with diameters between 1 and 2 mm increases. These two findings imply a general broadening of the corresponding velocity distributions. Potential explanations for the occurrence of sub‐terminal drops are given based on turbulence (small raindrops respond faster to changes in air conditions), drop oscillations (which produce larger transit times through the instrument sampling volume) and the enhancement of transverse drifts and trajectory deviations with respect to the vertical. However, other possibilities should be also addressed for drops with the largest fall speed anomalies (greater than two times the instrument uncertainty) as well as their implications for microphysical processes.
Ceftazidime-avibactam is a combination of β-lactam/β-lactamase inhibitor, the use of which is restricted to some clinical cases, including cystic fibrosis patients infected with multidrug-resistant
, ...in which mutation is the main driver of resistance. This study aims to predict the mechanisms of mutation-driven resistance that are selected for when
is challenged with either ceftazidime or ceftazidime-avibactam. For this purpose,
PA14 was submitted to experimental evolution in the absence of antibiotics and in the presence of increasing concentrations of ceftazidime or ceftazidime-avibactam for 30 consecutive days. Final populations were analyzed by whole-genome sequencing. All evolved populations reached similar levels of ceftazidime resistance. In addition, they were more susceptible to amikacin and produced pyomelanin. A first event in this evolution was the selection of large chromosomal deletions containing
(involved in pyomelanin production),
(involved in β-lactams resistance), and
(involved in aminoglycoside resistance). Besides mutations in
and
that regulate β-lactamase expression, mutations related to MexAB-OprM overexpression were prevalent. Ceftazidime-avibactam challenge selected mutants in the putative efflux pump
and
and in a two-component system (
and
), likely regulating its expression. All populations produced pyomelanin and were more susceptible to aminoglycosides, likely due to the selection of large chromosomal deletions. Since pyomelanin-producing mutants presenting similar deletions are regularly isolated from infections, the potential aminoglycoside hypersusceptiblity and reduced β-lactam susceptibility of pyomelanin-producing
should be taken into consideration for treating infections caused by these isolates.
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