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1.
Curr Opin Clin Nutr Metab Care ; 27(2): 98-105, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-37874045

RESUMO

PURPOSE OF REVIEW: This review uses the hierarchy of evidence as a framework to critically evaluate the effect of long chain n -3 polyunsaturated fatty acid (LC n -3 PUFA) ingestion alone, or as an adjunctive intervention to resistance training, on muscle health-related outcomes in healthy and clinical older adult populations. RECENT FINDINGS: Systematic reviews and meta-analyses of randomized controlled trials consistently report small, but clinically-relevant, effects of LC n -3 PUFA ingestion on strength outcomes, whereas mixed findings have been reported regarding changes in muscle mass and physical function. Cohort studies indicate an association between higher dietary LC n -3 PUFA intake and reduced likelihood of a sarcopenia diagnosis. Acute metabolic studies provide limited evidence for an effect of LC n -3 PUFA ingestion alone, or in combination with resistance training, on free-living integrated rates of MPS, static markers of muscle protein breakdown, or satellite cell activation in healthy older adults. SUMMARY: Recent data supports the efficacy of LCn-3 PUFA ingestion to facilitate small, but clinically relevant, improvements in muscle strength in healthy and clinical older adult populations. The mechanism(s) that underpin the action of LC n -3 PUFA in promoting strength outcomes remain unknown, but likely relate to neuromuscular function.


Assuntos
Ácidos Graxos Ômega-3 , Sarcopenia , Humanos , Idoso , Ácidos Graxos Ômega-3/metabolismo , Suplementos Nutricionais , Sarcopenia/metabolismo , Força Muscular , Ácidos Graxos/metabolismo , Músculo Esquelético/metabolismo
2.
Diabetes Obes Metab ; 26(3): 860-870, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37997550

RESUMO

AIM: This study aimed to contrast the associations of five common diet scores with severe non-alcoholic fatty liver disease (NAFLD) incidence. MATERIALS AND METHODS: In total, 162 999 UK Biobank participants were included in this prospective population-based study. Five international diet scores were included: the 14-Item Mediterranean Diet Adherence Screener (MEDAS-14), the Recommended Food Score (RFS), the Healthy Diet Indicator (HDI), the Mediterranean Diet Score and the Mediterranean-DASH Intervention for Neurodegenerative Delay score. As each score has different measurements and scales, all scores were standardized and categorized into quartiles. Cox proportional hazard models adjusted for confounder factors investigated associations between the standardized quartiles and severe NAFLD incidence. RESULTS: Over a median follow-up of 10.2 years, 1370 participants were diagnosed with severe NAFLD. When the analyses were fully adjusted, participants in quartile 4 using the MEDAS-14 and RFS scores, as well as those in quartiles 2 and 3 using the HDI score, had a significantly lower risk of severe incident NAFLD compared with those in quartile 1. The lowest risk was observed in quartile 4 for the MEDAS-14 score [hazard ratio (HR): 0.76 (95% confidence interval (CI): 0.62-0.94)] and the RFS score [HR: 0.82 (95% CI: 0.69-0.96)] and as well as in quartile 2 in the HDI score [HR: 0.80 (95% CI: 0.70-0.91)]. CONCLUSION: MEDAS-14, RFS and HDI scores were the strongest diet score predictors of severe NAFLD. A healthy diet might protect against NAFLD development irrespective of the specific approach used to assess diet. However, following these score recommendations could represent optimal dietary approaches to mitigate NAFLD risk.


Assuntos
Dieta Mediterrânea , Hepatopatia Gordurosa não Alcoólica , Humanos , Hepatopatia Gordurosa não Alcoólica/epidemiologia , Hepatopatia Gordurosa não Alcoólica/etiologia , Estudos Prospectivos , Fatores de Risco , Bancos de Espécimes Biológicos , Biobanco do Reino Unido , Dieta/efeitos adversos
3.
Nutr Metab Cardiovasc Dis ; 34(7): 1731-1740, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38664123

RESUMO

BACKGROUND AND AIMS: Research into the relationship between an Energy-adjusted Diet-Inflammatory Index (E-DII) and a wider health-related biomarkers profile is limited. Much of the existing evidence centers on traditional metabolic biomarkers in populations with chronic diseases, with scarce data on healthy individuals. Thus, this study aims to investigate the association between an E-DII score and 30 biomarkers spanning metabolic health, endocrine, bone health, liver function, cardiovascular, and renal functions, in healthy individuals. METHODS AND RESULTS: 66,978 healthy UK Biobank participants, the overall mean age was 55.3 (7.9) years were included in this cross-sectional study. E-DII scores, based on 18 food parameters, were categorised as anti-inflammatory (E-DII < -1), neutral (-1 to 1), and pro-inflammatory (>1). Regression analyses, adjusted for confounding factors, were conducted to investigate the association of 30 biomarkers with E-DII. Compared to those with an anti-inflammatory diet, individuals with a pro-inflammatory diet had increased levels of 16 biomarkers, including six cardiometabolic, five liver, and four renal markers. The concentration difference ranged from 0.27 SD for creatinine to 0.03 SD for total cholesterol. Conversely, those on a pro-inflammatory diet had decreased concentrations in six biomarkers, including two for endocrine and cardiometabolic. The association range varied from -0.04 for IGF-1 to -0.23 for SHBG. CONCLUSION: This study highlighted that a pro-inflammatory diet was associated with an adverse profile of biomarkers linked to cardiometabolic health, endocrine, liver function, and renal health.


Assuntos
Biomarcadores , Mediadores da Inflamação , Inflamação , Rim , Fígado , Humanos , Estudos Transversais , Masculino , Pessoa de Meia-Idade , Biomarcadores/sangue , Feminino , Reino Unido/epidemiologia , Idoso , Rim/fisiopatologia , Inflamação/sangue , Inflamação/diagnóstico , Adulto , Mediadores da Inflamação/sangue , Fígado/metabolismo , Fatores de Risco Cardiometabólico , Dieta/efeitos adversos , Medição de Risco , Bancos de Espécimes Biológicos , Osso e Ossos/metabolismo , Biobanco do Reino Unido
4.
Nature ; 544(7648): 92-95, 2017 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-28355184

RESUMO

Mosquitoes exhibit unusual wing kinematics; their long, slender wings flap at remarkably high frequencies for their size (>800 Hz)and with lower stroke amplitudes than any other insect group. This shifts weight support away from the translation-dominated, aerodynamic mechanisms used by most insects, as well as by helicopters and aeroplanes, towards poorly understood rotational mechanisms that occur when pitching at the end of each half-stroke. Here we report free-flight mosquito wing kinematics, solve the full Navier-Stokes equations using computational fluid dynamics with overset grids, and validate our results with in vivo flow measurements. We show that, although mosquitoes use familiar separated flow patterns, much of the aerodynamic force that supports their weight is generated in a manner unlike any previously described for a flying animal. There are three key features: leading-edge vortices (a well-known mechanism that appears to be almost ubiquitous in insect flight), trailing-edge vortices caused by a form of wake capture at stroke reversal, and rotational drag. The two new elements are largely independent of the wing velocity, instead relying on rapid changes in the pitch angle (wing rotation) at the end of each half-stroke, and they are therefore relatively immune to the shallow flapping amplitude. Moreover, these mechanisms are particularly well suited to high aspect ratio mosquito wings.


Assuntos
Culex/anatomia & histologia , Culex/fisiologia , Voo Animal/fisiologia , Rotação , Asas de Animais/anatomia & histologia , Asas de Animais/fisiologia , Movimentos do Ar , Animais , Fenômenos Biomecânicos , Hidrodinâmica , Masculino , Reprodutibilidade dos Testes
5.
Environ Sci Technol ; 56(14): 10258-10268, 2022 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-35762409

RESUMO

The presence of volatile organic compounds (VOCs) in unprocessed natural gas (NG) is well documented; however, the degree to which VOCs are present in NG at the point of end use is largely uncharacterized. We collected 234 whole NG samples across 69 unique residential locations across the Greater Boston metropolitan area, Massachusetts. NG samples were measured for methane (CH4), ethane (C2H6), and nonmethane VOC (NMVOC) content (including tentatively identified compounds) using commercially available USEPA analytical methods. Results revealed 296 unique NMVOC constituents in end use NG, of which 21 (or approximately 7%) were designated as hazardous air pollutants. Benzene (bootstrapped mean = 164 ppbv; SD = 16; 95% CI: 134-196) was detected in 95% of samples along with hexane (98% detection), toluene (94%), heptane (94%), and cyclohexane (89%), contributing to a mean total concentration of NMVOCs in distribution-grade NG of 6.0 ppmv (95% CI: 5.5-6.6). While total VOCs exhibited significant spatial variability, over twice as much temporal variability was observed, with a wintertime NG benzene concentration nearly eight-fold greater than summertime. By using previous NG leakage data, we estimated that 120-356 kg/yr of annual NG benzene emissions throughout Greater Boston are not currently accounted for in emissions inventories, along with an unaccounted-for indoor portion. NG-odorant content (tert-butyl mercaptan and isopropyl mercaptan) was used to estimate that a mean NG-CH4 concentration of 21.3 ppmv (95% CI: 16.7-25.9) could persist undetected in ambient air given known odor detection thresholds. This implies that indoor NG leakage may be an underappreciated source of both CH4 and associated VOCs.


Assuntos
Poluentes Atmosféricos , Compostos Orgânicos Voláteis , Poluentes Atmosféricos/análise , Benzeno , Monitoramento Ambiental/métodos , Gás Natural
6.
Glob Chang Biol ; 24(10): 4841-4856, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29949220

RESUMO

Changes in evapotranspiration (ET) from terrestrial ecosystems affect their water yield (WY), with considerable ecological and economic consequences. Increases in surface runoff observed over the past century have been attributed to increasing atmospheric CO2 concentrations resulting in reduced ET by terrestrial ecosystems. Here, we evaluate the water balance of a Pinus taeda (L.) forest with a broadleaf component that was exposed to atmospheric [CO2 ] enrichment (ECO2 ; +200 ppm) for over 17 years and fertilization for 6 years, monitored with hundreds of environmental and sap flux sensors on a half-hourly basis. These measurements were synthesized using a one-dimensional Richard's equation model to evaluate treatment differences in transpiration (T), evaporation (E), ET, and WY. We found that ECO2 did not create significant differences in stand T, ET, or WY under either native or enhanced soil fertility, despite a 20% and 13% increase in leaf area index, respectively. While T, ET, and WY responded to fertilization, this response was weak (<3% of mean annual precipitation). Likewise, while E responded to ECO2 in the first 7 years of the study, this effect was of negligible magnitude (<1% mean annual precipitation). Given the global range of conifers similar to P. taeda, our results imply that recent observations of increased global streamflow cannot be attributed to decreases in ET across all ecosystems, demonstrating a great need for model-data synthesis activities to incorporate our current understanding of terrestrial vegetation in global water cycle models.


Assuntos
Dióxido de Carbono/metabolismo , Florestas , Pinus taeda/metabolismo , Transpiração Vegetal , Solo/química , Água/metabolismo , Ecossistema , Folhas de Planta/fisiologia
8.
Proc Natl Acad Sci U S A ; 112(7): 1941-6, 2015 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-25617375

RESUMO

Methane emissions from natural gas delivery and end use must be quantified to evaluate the environmental impacts of natural gas and to develop and assess the efficacy of emission reduction strategies. We report natural gas emission rates for 1 y in the urban region of Boston, using a comprehensive atmospheric measurement and modeling framework. Continuous methane observations from four stations are combined with a high-resolution transport model to quantify the regional average emission flux, 18.5 ± 3.7 (95% confidence interval) g CH4 ⋅ m(-2) ⋅ y(-1). Simultaneous observations of atmospheric ethane, compared with the ethane-to-methane ratio in the pipeline gas delivered to the region, demonstrate that natural gas accounted for ∼ 60-100% of methane emissions, depending on season. Using government statistics and geospatial data on natural gas use, we find the average fractional loss rate to the atmosphere from all downstream components of the natural gas system, including transmission, distribution, and end use, was 2.7 ± 0.6% in the Boston urban region, with little seasonal variability. This fraction is notably higher than the 1.1% implied by the most closely comparable emission inventory.


Assuntos
Poluentes Atmosféricos/análise , Metano/análise , Gás Natural , Urbanização , Boston
9.
Environ Sci Technol ; 48(3): 2051-8, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24432903

RESUMO

Pipeline safety in the United States has increased in recent decades, but incidents involving natural gas pipelines still cause an average of 17 fatalities and $133 M in property damage annually. Natural gas leaks are also the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. To reduce pipeline leakage and increase consumer safety, we deployed a Picarro G2301 Cavity Ring-Down Spectrometer in a car, mapping 5893 natural gas leaks (2.5 to 88.6 ppm CH4) across 1500 road miles of Washington, DC. The δ(13)C-isotopic signatures of the methane (-38.2‰ ± 3.9‰ s.d.) and ethane (-36.5 ± 1.1 s.d.) and the CH4:C2H6 ratios (25.5 ± 8.9 s.d.) closely matched the pipeline gas (-39.0‰ and -36.2‰ for methane and ethane; 19.0 for CH4/C2H6). Emissions from four street leaks ranged from 9200 to 38,200 L CH4 day(-1) each, comparable to natural gas used by 1.7 to 7.0 homes, respectively. At 19 tested locations, 12 potentially explosive (Grade 1) methane concentrations of 50,000 to 500,000 ppm were detected in manholes. Financial incentives and targeted programs among companies, public utility commissions, and scientists to reduce leaks and replace old cast-iron pipes will improve consumer safety and air quality, save money, and lower greenhouse gas emissions.


Assuntos
Poluentes Atmosféricos/análise , Gás Natural/análise , Isótopos de Carbono , District of Columbia , Geografia , Substâncias Perigosas/análise , Metano/análise
10.
Front Nutr ; 11: 1349538, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38751735

RESUMO

Introduction: Understanding how socioeconomic markers interact could inform future policies aimed at increasing adherence to a healthy diet. Methods: This cross-sectional study included 437,860 participants from the UK Biobank. Dietary intake was self-reported. Were used as measures socioeconomic education level, income and Townsend deprivation index. A healthy diet score was defined using current dietary recommendations for nine food items and one point was assigned for meeting the recommendation for each. Good adherence to a healthy diet was defined as the top 75th percentile, while poor adherence was defined as the lowest 25th percentile. Poisson regression was used to investigate adherence to dietary recommendations. Results: There were significant trends whereby diet scores tended to be less healthy as deprivation markers increased. The diet score trends were greater for education compared to area deprivation and income. Compared to participants with the highest level of education, those with the lowest education were found to be 48% less likely to adhere to a healthy diet (95% Confidence Interval [CI]: 0.60-0.64). Additionally, participants with the lowest income level were 33% less likely to maintain a healthy diet (95% CI: 0.73-0.81), and those in the most deprived areas were 13% less likely (95% CI: 0.84-0.91). Discussion/conclussion: Among the three measured proxies of socioeconomic status - education, income, and area deprivation - low education emerged as the strongest factor associated with lower adherence to a healthy diet.

11.
Am J Bot ; 100(3): 465-6, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23455482

RESUMO

In this response, we address the criticisms put forth by Tomlinson and Quinn (American Journal of Botany 100: 461-464) about our original publication on secondary stem lengthening in Iriartea deltoidea palms (American Journal of Botany 99: 607-613) and find areas on which we may agree. We address our figure of a typical palm vascular bundle; the location, timing, and species where secondary lengthening would likely occur; and our measurement of internodes in various palms as well as our choice of individuals. Our original observations were a novel finding in the field of palm biology, and we invite more research and investigation on this subject.


Assuntos
Arecaceae/anatomia & histologia , Arecaceae/crescimento & desenvolvimento , Caules de Planta/anatomia & histologia , Caules de Planta/crescimento & desenvolvimento , Árvores/anatomia & histologia , Árvores/crescimento & desenvolvimento
12.
Physiol Plant ; 147(4): 502-13, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22905764

RESUMO

Infection by eastern dwarf mistletoe (Arceuthobium pusillum) modifies needle and branch morphology and hastens white spruce (Picea glauca) mortality. We examined potential causal mechanisms and assessed the impacts of infection-induced alterations to host development and performance across scales ranging from needle hormone contents to bole expansion. Needles on infected branches (IBs) possessed higher total cytokinin (CK) and lower abscisic acid contents than needles on uninfected branches (UBs). IBs exhibited greater xylem growth than same-aged UBs, which is consistent with the promotive effect of CKs on vascular differentiation and organ sink strength. Elevated CK content may also explain the dense secondary and tertiary branching observed at the site of infection, i.e. the formation of 'witches' brooms' with significantly lower light capture efficiencies. Observed hormone perturbations were consistent with higher rates of transpiration, lower water use efficiencies (WUEs) and more negative needle carbon isotope ratios observed for IBs. Observed reductions in needle size allowed IBs to compensate for reduced hydraulic conductivity. Severe infections resulted in dramatically decreased diameter growth of the bole. It seems likely that the modifications to host hormone contents by eastern dwarf mistletoe infection led white spruce trees to dedicate a disproportionate fraction of their photoassimilate and other resources to self-shaded branches with low WUE. This would have decreased the potential for fixed carbon accumulation, generating a decline in the whole-tree resource pool. As mistletoe infections grew in size and the number of IBs increased, this burden was manifested as increasingly greater reductions in bole growth.


Assuntos
Interações Hospedeiro-Parasita , Picea/crescimento & desenvolvimento , Picea/metabolismo , Viscaceae/crescimento & desenvolvimento , Ácido Abscísico/metabolismo , Dióxido de Carbono/metabolismo , Isótopos de Carbono/análise , Isótopos de Carbono/metabolismo , Luz , Maine , Reguladores de Crescimento de Plantas/metabolismo , Brotos de Planta/fisiologia , Caules de Planta/fisiologia , Água
13.
PLoS One ; 18(11): e0295055, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38032978

RESUMO

From wellhead to burner tip, each component of the natural gas process chain has come under increased scrutiny for the presence and magnitude of methane leaks, because of the large global warming potential of methane. Top-down measures of methane emissions in urban areas are significantly greater than bottom-up estimates. Recent research suggests this disparity might in part be explained by gas leaks from one of the least understood parts of the process chain: behind the gas meter in homes and buildings. However, little research has been performed in this area and few methods and data sets exist to measure or estimate them. We develop and test a simple and widely deployable closed chamber method that can be used for quantifying indoor methane emissions with an order-of-magnitude precision which allows for screening of indoor large volume ("super-emitting") leaks. We also perform test applications of the method finding indoor leaks in 90% of the 20 Greater Boston buildings studied and indoor methane emissions between 0.02-0.51 ft3 CH4 day-1 (0.4-10.3 g CH4 day-1) with a mean of 0.14 ft3 CH4 day-1 (2.8 g CH4 day-1). Our method provides a relatively simple way to scale up indoor methane emissions data collection. Increased data may reduce uncertainty in bottom-up inventories, and can be used to find super-emitting indoor emissions which may better explain the disparity between top-down and bottom-up post-meter emissions estimates.


Assuntos
Poluentes Atmosféricos , Metano , Metano/análise , Poluentes Atmosféricos/análise , Gás Natural/análise , Boston , Coleta de Dados
14.
Am J Bot ; 99(4): 607-13, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22434771

RESUMO

PREMISE OF THE STUDY: Although traditionally assumed that all height growth in trees occurs at apical meristems, sequential measurement of internode lengths in the palm Iriartea deltoidea suggested that stems were lengthening long after the differentiation of tissues and far below the apical meristem. This observation is difficult to reconcile with the fact that neither the water-conducting vessels nor the sugar-transporting sieve tube cells are capable of lengthening after differentiation. However, the vascular bundles in palms form a spiral within the stem and could theoretically lengthen if the spiral "straightened". METHODS: We marked stretches of internodes on small and medium-sized palms and measured their lengths over 2 years. Additionally, we collected material from small palms with short internodes and large palms with long internodes and made cross sections to determine the angle of vascular bundles within stems. KEY RESULTS: We found that stems lengthened (up to 12% over 2 years) below the apical meristem in small and medium-sized palms and that the spiral angle in vascular bundles of small palms was significantly larger than at the base of large palms indicating a straightening of the spiral. CONCLUSIONS: These results represent the first determination of "secondary lengthening" in tree stems as well as the most efficient method for height growth in terms of carbon investment. Likewise, elongation of stems allows palms to exhibit plasticity in height growth rates for more rapid growth when short-lived canopy gaps are present than they would have with apical growth alone.


Assuntos
Arecaceae/anatomia & histologia , Arecaceae/crescimento & desenvolvimento , Caules de Planta/anatomia & histologia , Caules de Planta/crescimento & desenvolvimento , Árvores/anatomia & histologia , Árvores/crescimento & desenvolvimento , Arecaceae/citologia , Caules de Planta/citologia , Feixe Vascular de Plantas/anatomia & histologia , Feixe Vascular de Plantas/citologia , Árvores/citologia
15.
J Orthop Res ; 40(2): 420-428, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-33713379

RESUMO

Staphylococcus aureus is a common organism in orthopedic infections, but little is known about the genetic diversity of strains during an infectious process. Using periprosthetic joint infection (PJI) as a model, a prospective study was designed to quantify genetic variation among S. aureus strains both among and within patients. Whole genome sequencing and multilocus sequence typing was performed to genotype these two populations at high resolution. In nasal cultures, 78% of strains were of clonal complexes CC5, CC8, and CC30. In PJI cultures, only 63% could be classified in these common clonal complexes. The PJI cultures had a larger proportion of atypical strains, and these atypical strains were associated with poor host status and compromised immune conditions. Mutations in genes involved in fibronectin binding (ebh, fnbA, clfA, and clfB) systematically distinguished later PJI isolates from the first PJI isolate from each patient. Repeated mutations in S. aureus genes associated with extracellular matrix binding were identified, suggesting adaptive, parallel evolution of S. aureus during the development of PJI.


Assuntos
Artrite Infecciosa , Infecções Estafilocócicas , Artrite Infecciosa/etiologia , Genótipo , Humanos , Estudos Prospectivos , Staphylococcus aureus/genética
16.
Oecologia ; 167(4): 925-35, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21656029

RESUMO

Because palms grow in highly varying climates and reach considerable heights, they present a unique opportunity to evaluate how environment and plant size impact hydraulic function. We studied hydraulic properties of petioles from palms of varying height from three species: Iriartea deltoidea, a tropical rainforest species; Mauritia flexuosa, a tropical rainforest, swamp species; and Washingtonia robusta, a subtropical species. We measured leaf areas, petiole cross-sectional areas, specific conductivity (K(S)), petiole anatomical properties, vulnerability to embolism and leaf water potentials and calculated petiole Huber values and leaf-specific conductivities (K(L)). Leaf and petiole cross-sectional areas varied widely with height. However, hydraulic properties including Huber values, K(S) and K(L), remained constant. The two palmate species, M. flexuosa and W. robusta, had larger Huber values than I. deltoidea, a pinnately-compound species which exhibited the highest K(S). Metaxylem vessel diameters and vascular bundle densities varied with height in opposing patterns to maintain petiole conductivities. I. deltoidea and W. robusta petioles had similar P(50) values (the point at which 50% of hydraulic conductivity is lost) averaged over all crown heights, but W. robusta exhibited more negative P(50) values in taller palms. Comparison of P (50) values with transpiring midday leaf water potentials, as well as a double-dye staining experiment in a 1-m-tall palm, suggested that a fairly significant amount of embolisms were occurring and refilled on a diurnal basis. Therefore, across palms differing widely in height and growing environments, we found convergence in water transport per unit leaf area (K(L)) with individuals exhibiting differing strategies for achieving this.


Assuntos
Arecaceae/anatomia & histologia , Folhas de Planta/anatomia & histologia , Arecaceae/metabolismo , Transporte Biológico , Ecossistema , Equador , New South Wales , Folhas de Planta/metabolismo , Caules de Planta/anatomia & histologia , Caules de Planta/metabolismo , Transpiração Vegetal , Especificidade da Espécie , Árvores/anatomia & histologia , Árvores/metabolismo , Água/metabolismo , Xilema/anatomia & histologia , Xilema/metabolismo
17.
Plant Cell Environ ; 33(10): 1671-81, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20492554

RESUMO

The unabated rise in atmospheric [CO(2)] is associated with increased air temperature. Yet, few CO(2)-enrichment studies have considered pre-industrial [CO(2)] or warming. Consequently, we quantified the interactive effects of growth [CO(2)] and temperature on photosynthesis of faster-growing Eucalyptus saligna and slower-growing E. sideroxylon. Well-watered and -fertilized tree seedlings were grown in a glasshouse at three atmospheric [CO(2)] (290, 400, and 650 µL L(-1)), and ambient (26/18 °C, day/night) and high (ambient + 4 °C) air temperature. Despite differences in growth rate, both eucalypts responded similarly to [CO(2)] and temperature treatments with few interactive effects. Light-saturated photosynthesis (A(sat)) and light- and [CO(2)]-saturated photosynthesis (A(max) ) increased by ∼ 50% and ∼ 10%, respectively, with each step-increase in growth [CO(2)], underpinned by a corresponding 6-11% up-regulation of maximal electron transport rate (J(max)). Maximal carboxylation rate (V(cmax)) was not affected by growth [CO(2)]. Thermal photosynthetic acclimation occurred such that A(sat) and A(max) were similar in ambient- and high-temperature-grown plants. At high temperature, the thermal optimum of A(sat) increased by 2-7 °C across [CO(2)] treatments. These results are the first to suggest that photosynthesis of well-watered and -fertilized eucalypt seedlings will remain strongly responsive to increasing atmospheric [CO(2)] in a future, warmer climate.


Assuntos
Dióxido de Carbono/metabolismo , Eucalyptus/metabolismo , Fotossíntese , Atmosfera , Eucalyptus/crescimento & desenvolvimento , Temperatura Alta , Nitrogênio/metabolismo , Folhas de Planta/metabolismo , Estômatos de Plantas/metabolismo , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Especificidade da Espécie , Temperatura , Fatores de Tempo
18.
Tree Physiol ; 30(5): 586-96, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20332372

RESUMO

To identify environmental and biological drivers of nocturnal vapour exchange, we quantified intra-annual, intra- and inter-specific variation in nocturnal water transport among ecologically diverse Eucalyptus species. We measured sap flux (J(s)) and leaf physiology (leaf surface conductance (g(s)), transpiration (E) and water potential (Psi(l))) in three to five trees of eight species. Over 1 year, nocturnal J(s) (J(s,n)) contributed 5-7% of total J(s) in the eight species. The principal environmental driver of J(s,n) was the product of atmospheric vapour pressure deficit (D) and wind speed (U). Selected observations suggest that trees with higher proportions of young foliage may exhibit greater J(s,n) and nocturnal g(s) (g(s,n)). Compared with other tree taxa, nocturnal water use in Eucalyptus was relatively low and more variable within than between species, suggesting that (i) Eucalyptus as a group exerts strong nocturnal stomatal control over water loss and (ii) prediction of nocturnal flux in Eucalyptus may depend on simultaneous knowledge of intra-specific tree traits and nocturnal atmospheric conditions.


Assuntos
Eucalyptus/classificação , Eucalyptus/fisiologia , Água/metabolismo , Transporte Biológico/fisiologia , Ritmo Circadiano , Folhas de Planta/fisiologia , Especificidade da Espécie
19.
Heliyon ; 6(10): e04876, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33088932

RESUMO

Leaked methane from natural gas distribution pipelines is a significant human and environmental health problem in urban areas. To assess this risk, urban mobile methane leak surveys were conducted, using innovative methodology, on the streets of Hartford, Danbury, and New London, Connecticut, in March 2019. The Hartford survey was done to determine if results from a 2016 survey (Keyes et al., 2019) were persistent, and surveys in additional towns were done to determine if similar findings could be made using an identical approach. Results show that Hartford continues to be problematic, with approximately 3.4 leaks per road mile observed in 2016 and 4.3 leaks per mile estimated in 2019, similar to that previously found in Boston, Massachusetts (Phillips et al., 2013). A preliminary estimate of methane leaks in Hartford is 0.86 metric tonnes per day (or 313 metric tonnes per year), equivalent to 42,840 cubic feet per day of natural gas, and a daily gas consumption of approximately 214 U.S. households. Moreover, the surveys and analyses done for Danbury and New London also reveal problematic leaks, particularly for Danbury with an estimated 3.6 leaks per mile. Although road miles covered in New London were more limited, the survey revealed leak-prone areas, albeit with a range of methane readings lower than those in Hartford and Danbury. Data collection methods for all studies is first reported here and are readily transferable to similar urban settings. This work demonstrates the actionable value that can be gained from data-driven evaluations of urban pipeline performance, and if supplemented with a map of leak-prone pipe geo-location, and information on pipeline operating pressures, will provide a spatial database facilitating proactive repair and replacement of leak-prone urban pipes, a considerable improvement compared to reactive mitigation of human-reported leaks. While this work pertains to the selected urban towns in the Northeast, it exemplifies issues and opportunities nationwide in the United States.

20.
Ecology ; 101(11): e03173, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32852804

RESUMO

Climate models project higher growing-season temperatures and a decline in the depth and duration of winter snowpack throughout many north temperate ecosystems over the next century. A smaller snowpack is projected to induce more frequent soil freeze/thaw cycles in winter in northern hardwood forests of the northeastern United States. We measured the combined effects of warmer growing-season soil temperatures and increased winter freeze/thaw cycles on rates of leaf-level photosynthesis and transpiration (sap flow) of red maple (Acer rubrum) trees in a northern hardwood forest at the Climate Change Across Seasons Experiment at Hubbard Brook Experimental Forest in New Hampshire. Soil temperatures were warmed 5°C above ambient temperatures during the growing season and soil freeze/thaw cycles were induced in winter to mimic the projected changes in soil temperature over the next century. Relative to reference plots, growing-season soil warming increased rates of leaf-level photosynthesis by up to 85.32 ± 4.33%, but these gains were completely offset by soil freeze/thaw cycles in winter, suggesting that increased freeze/thaw cycles in winter over the next 100 yr will reduce the effect of warming on leaf-level carbon gains. Soil warming in the growing season increased rates of transpiration per kilopascal of vapor pressure deficit (VPD) by up to 727.39 ± 0.28%, even when trees were exposed to increased frequency of soil freeze/thaw cycles in the previous winter, which could influence regional hydrology in the future. Using climate projections downscaled from the Coupled Model Intercomparison Project, we project increased rates of whole-season transpiration in these forests over the next century by 42-61%. We also project 52-77 additional days when daily air temperatures will be above the long-term average daily maximum during the growing season at Hubbard Brook. Together, these results show that projected changes in climate across both the growing season and winter are likely to cause greater rates of water uptake and have no effect on rates of leaf-level carbon uptake by trees, with potential ecosystem consequences for hydrology and carbon cycling in northern hardwood forests.


Assuntos
Ecossistema , Solo , Mudança Climática , Florestas , New Hampshire , Estações do Ano , Neve
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