An authoritative desk-top reference work for students of geography, the environment and sustainability, which through a series of 101 interconnected questions and answers spanning ten thematic ...sections, provides a comprehensive survey of humankind's impact on the global environment from the Late Stone Age to the present day.
Rationnel La qualité de la relation médecin-patient est une clé de voûte des soins, requise en particulier pour les patients atteints de maladies chroniques telles que le diabète. Elle influence la ...satisfaction des patients, l'observance aux traitements et leurs résultats. Rares sont les publications qui rapportent l'évaluation de logiciels de communication par les patients et professionnels de la santé. Patients et Méthodes 30 patients atteints de maladies chroniques, de 27 à 79 ans (53 % 60+), ont été recrutés « en vie réelle », suivant le registre des consultations, pour évaluer une interface de télémédecine en connexion directe avec leur médecin. Une visioconférence personnalisée est équipée de partage en totale symétrie, de résultats médicaux, sur un réseau intranet sécurisé. Résultats Le temps de déplacement à l'hôpital était de 21 ± 17 mn. Durant les deux dernières années, les patients ont fait 7 ± 5 visites à leur hôpital ; le temps d'attente à l'hôpital était de 23 ± 26 mn. Le mode de recrutement a laissé moins de 15 mn à la formation. Cependant 24 patients (80 %) l'ont estimée satisfaisante. Les possibilités de compréhension mutuelle et de perception des échanges au cours de la téléconsultation ont été jugées satisfaisantes par 12 patients (43 %), excellentes par 16 (57 %). Deux patients n'ont pas répondu. Vingt patients (72 %) ont pleinement approuvé l'utilisation de l'interface pour le maintien d'une relation personnelle et confidentielle avec leur médecin ; 5 (18 %) l'ont simplement approuvée ; 1 l'a considérée quelque peu utile et 2 l'ont désapprouvée. Les réponses ne sont pas liées à l'âge (r = 0,127). Conclusions Cette étude montre la satisfaction et l'adhésion des patients à la téléconsultation en alternance avec leur parcours traditionnel. Une évaluation médico-économique randomisée est justifiée.
The ninth century collapse and abandonment of the Central Maya Lowlands in the Yucatán peninsular region were the result of complex human–environment interactions. Large-scale Maya landscape ...alterations and demands placed on resources and ecosystem services generated high-stress environmental conditions that were amplified by increasing climatic aridity. Coincident with this stress, the flow of commerce shifted from land transit across the peninsula to sea-borne transit around it. These changing socioeconomic and environmental conditions generated increasing societal conflicts, diminished control by the Maya elite, and led to decisions to move elsewhere in the peninsular region rather than incur the high costs of maintaining the human–environment systems in place. After abandonment, the environment of the Central Maya Lowlands largely recovered, although altered from its state before Maya occupation; the population never recovered. This history and the spatial and temporal variability in the pattern of collapse and abandonment throughout the Maya lowlands support the case for different conditions, opportunities, and constraints in the prevailing human–environment systems and the decisions to confront them. The Maya case lends insights for the use of paleo- and historical analogs to inform contemporary global environmental change and sustainability.
Land change science has emerged as a fundamental component of global environmental change and sustainability research. This interdisciplinary field seeks to understand the dynamics of land cover and ...land use as a coupled human-environment system to address theory, concepts, models, and applications relevant to environmental and societal problems, including the intersection of the two. The major components and advances in land change are addressed: observation and monitoring; understanding the coupled system-causes, impacts, and consequences; modeling; and synthesis issues. The six articles of the special feature are introduced and situated within these components of study.
Extracellular enzymes synthesized by soil microbes play a central role in the biogeochemical cycling of nutrients in the environment. The pH optima of eight hydrolytic enzymes involved in the cycles ...of carbon, nitrogen, phosphorus, and sulfur, were assessed in a series of tropical forest soils of contrasting pH values from the Republic of Panama. Assays were conducted using 4-methylumbelliferone-linked fluorogenic substrates in modified universal buffer. Optimum pH values differed markedly among enzymes and soils. Enzymes were grouped into three classes based on their pH optima: (i) enzymes with acidic pH optima that were consistent among soils (cellobiohydrolase, β-xylanase, and arylsulfatase), (ii) enzymes with acidic pH optima that varied systematically with soil pH, with the most acidic pH optima in the most acidic soils (α-glucosidase, β-glucosidase, and N-acetyl-β-glucosaminidase), and (iii) enzymes with an optimum pH in either the acid range or the alkaline range depending on soil pH (phosphomonoesterase and phosphodiesterase). The optimum pH values of phosphomonoesterase were consistent among soils, being 4 to 5 for acid phosphomonoesterase and 10 to 11 for alkaline phosphomonoesterase. In contrast, the optimum pH for phosphodiesterase activity varied systematically with soil pH, with the most acidic pH optima (3.0) in the most acidic soils and the most alkaline pH optima (pH 10) in near-neutral soils. Arylsulfatase activity had a very acidic optimum pH in all soils (pH less-than or equal to3.0) irrespective of soil pH. The differences in pH optima may be linked to the origins of the enzymes and/or the degree of stabilization on solid surfaces. The results have important implications for the interpretation of hydrolytic enzyme assays using fluorogenic substrates.
Tropical soils contain one-third of the carbon stored in soils globally
, so destabilization of soil organic matter caused by the warming predicted for tropical regions this century
could accelerate ...climate change by releasing additional carbon dioxide (CO
) to the atmosphere
. Theory predicts that warming should cause only modest carbon loss from tropical soils relative to those at higher latitudes
, but there have been no warming experiments in tropical forests to test this
. Here we show that in situ experimental warming of a lowland tropical forest soil on Barro Colorado Island, Panama, caused an unexpectedly large increase in soil CO
emissions. Two years of warming of the whole soil profile by four degrees Celsius increased CO
emissions by 55 per cent compared to soils at ambient temperature. The additional CO
originated from heterotrophic rather than autotrophic sources, and equated to a loss of 8.2 ± 4.2 (one standard error) tonnes of carbon per hectare per year from the breakdown of soil organic matter. During this time, we detected no acclimation of respiration rates, no thermal compensation or change in the temperature sensitivity of enzyme activities, and no change in microbial carbon-use efficiency. These results demonstrate that soil carbon in tropical forests is highly sensitive to warming, creating a potentially substantial positive feedback to climate change.
Soil contains more carbon than the atmosphere and vegetation combined. Understanding the mechanisms controlling the accumulation and stability of soil carbon is critical to predicting the Earth's ...future climate. Recent studies suggest that decomposition of soil organic matter is often limited by nitrogen availability to microbes and that plants, via their fungal symbionts, compete directly with free-living decomposers for nitrogen. Ectomycorrhizal and ericoid mycorrhizal (EEM) fungi produce nitrogen-degrading enzymes, allowing them greater access to organic nitrogen sources than arbuscular mycorrhizal (AM) fungi. This leads to the theoretical prediction that soil carbon storage is greater in ecosystems dominated by EEM fungi than in those dominated by AM fungi. Using global data sets, we show that soil in ecosystems dominated by EEM-associated plants contains 70% more carbon per unit nitrogen than soil in ecosystems dominated by AM-associated plants. The effect of mycorrhizal type on soil carbon is independent of, and of far larger consequence than, the effects of net primary production, temperature, precipitation and soil clay content. Hence the effect of mycorrhizal type on soil carbon content holds at the global scale. This finding links the functional traits of mycorrhizal fungi to carbon storage at ecosystem-to-global scales, suggesting that plant-decomposer competition for nutrients exerts a fundamental control over the terrestrial carbon cycle.
The current study systematically reviewed, summarized and meta-analyzed the clinical features of the vaccines in clinical trials to provide a better estimate of their efficacy, side effects and ...immunogenicity. All relevant publications were systematically searched and collected from major databases up to 12 March 2021. A total of 25 RCTs (123 datasets), 58,889 cases that received the COVID-19 vaccine and 46,638 controls who received placebo were included in the meta-analysis. In total, mRNA-based and adenovirus-vectored COVID-19 vaccines had 94.6% (95% CI 0.936–0.954) and 80.2% (95% CI 0.56–0.93) efficacy in phase II/III RCTs, respectively. Efficacy of the adenovirus-vectored vaccine after the first (97.6%; 95% CI 0.939–0.997) and second (98.2%; 95% CI 0.980–0.984) doses was the highest against receptor-binding domain (RBD) antigen after 3 weeks of injections. The mRNA-based vaccines had the highest level of side effects reported except for diarrhea and arthralgia. Aluminum-adjuvanted vaccines had the lowest systemic and local side effects between vaccines’ adjuvant or without adjuvant, except for injection site redness. The adenovirus-vectored and mRNA-based vaccines for COVID-19 showed the highest efficacy after first and second doses, respectively. The mRNA-based vaccines had higher side effects. Remarkably few experienced extreme adverse effects and all stimulated robust immune responses.
A large fraction of the world grasslands and savannas are undergoing a rapid shift from herbaceous to woody-plant dominance. This land-cover change is expected to lead to a loss in livestock ...production (LP), but the impacts of woody-plant encroachment on this crucial ecosystem service have not been assessed. We evaluate how tree cover (TC) has affected LP at large spatial scales in rangelands of contrasting social–economic characteristics in the United States and Argentina. Our models indicate that in areas of high productivity, a 1% increase in TC results in a reduction in LP ranging from 0.6 to 1.6 reproductive cows (Rc) per km ². Mean LP in the United States is 27 Rc per km ², so a 1% increase in TC results in a 2.5% decrease in mean LP. This effect is large considering that woody-plant cover has been described as increasing at 0.5% to 2% per y. On the contrary, in areas of low productivity, increased TC had a positive effect on LP. Our results also show that ecological factors account for a larger fraction of LP variability in Argentinean than in US rangelands. Differences in the relative importance of ecological versus nonecological drivers of LP in Argentina and the United States suggest that the valuation of ecosystem services between these two rangelands might be different. Current management strategies in Argentina are likely designed to maximize LP for various reasons we are unable to explore in this effort, whereas land managers in the United States may be optimizing multiple ecosystem services, including conservation or recreation, alongside LP.
1. Organic phosphorus is abundant in soil and its turnover can supply a considerable fraction of the phosphorus taken up by natural vegetation. Despite this, the ecological significance of organic ...phosphorus remains poorly understood, which is remarkable given the biological importance of phosphorus in terrestrial environments. 2. Of particular interest is the possibility that coexisting plant species partition soil organic phosphorus to reduce competition. This seems likely given the large number of biologically available phosphorus compounds that occur in soil and the variety of mechanisms by which plants can utilize them. 3. Here I propose a conceptual model of resource partitioning for soil phosphorus. The model describes a hypothetical example of four coexisting plant species that differ in their ability to access soil organic phosphorus compounds, which are grouped to form a gradient of biological availability based on the processes involved in their utilization by plants. 4. Synthesis: Resource partitioning for soil phosphorus could provide an additional mechanism to explain the coexistence and distribution of plant species. It is likely to occur widely in terrestrial environments, but should have greatest ecological significance wherever productivity is limited by the availability of soil phosphorus. This includes freshwater wetlands, super-humid temperate regions and ecosystems developed on strongly-weathered soils that cover vast areas of ancient landscapes in Africa, Australia and South America.
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