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1.
Philos Trans R Soc Lond B Biol Sci ; 378(1867): 20210081, 2023 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-36373926

RESUMO

Many natural forests in Southeast Asia are degraded following decades of logging. Restoration of these forests is delayed by ongoing logging and tropical cyclones, but the implications for recovery are largely uncertain. We analysed meteorological, satellite and forest inventory plot data to assess the effect of Typhoon Doksuri, a major tropical cyclone, on the forest landscapes of central Vietnam consisting of natural forests and plantations. We estimated the return period for a cyclone of this intensity to be 40 years. Plantations were almost twice as likely to suffer cyclone damage compared to natural forests. Logged natural forests (9-12 years after cessation of government-licensed logging) were surveyed before and after the storm with 2 years between measurements and remained a small biomass carbon sink (0.1 ± 0.3 Mg C ha-1 yr-1) over this period. The cyclone reduced the carbon sink of recovering natural forests by an average of 0.85 Mg C ha-1 yr-1, less than the carbon loss due to ongoing unlicensed logging. Restoration of forest landscapes in Southeast Asia requires a reduction in unlicensed logging and prevention of further conversion of degraded natural forests to plantations, particularly in landscapes prone to tropical cyclones where natural forests provide a resilient carbon sink. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.


Assuntos
Tempestades Ciclônicas , Agricultura Florestal , Ecossistema , Vietnã , Florestas , Clima Tropical , Árvores , Conservação dos Recursos Naturais
2.
Environ Sci Pollut Res Int ; 29(49): 74554-74568, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35639309

RESUMO

Global warming is a global menace mainly driven by human anthropogenic activities. There is a need for environmental sustainability amidst increased economic growth. To this end, this study draws motivation from the United Nations Sustainable Development Goals (UNSDGs) with special focus on climate change mitigation and ecological balance. Thus, the present study analyses the dynamic relationship between economic growth, conventional energy consumption, access to technological innovation, economic globalisation, and the pertinent role of institutional quality for the case of the Russian Federation. This study employed novel combined Bayer and Hack cointegration test in conjunction with Pesaran's ARDL bounds testing for robustness. Both tests validate a long-run equilibrium relationship between the outlined variables. Furthermore, empirical results show that increase in economic activities and consumption of energy that stem from a fossil-fuel basis both have deteriorating effect on environmental sustainability for Russia. Additionally, effect of globalisation shows mixed results, such as, in the short run, economic globalisation dampens environmental quality as increase in global integration exacerbates environmental quality, while, in the long term, globalisation improves the quality of the environment. On the contribution of institutional quality, it improves environmental sustainability over the investigated period. Interestingly, renewable is seen as a panacea for environmental sustainability in the Russian Federation given its pertinent effect to improve the environment of Russia. From a policy lens, there is need for a paradigm shift to renewables and clean technologies to mitigate the effect of climate change issues. The concluding section presents more policy strategies.


Assuntos
Dióxido de Carbono , Desenvolvimento Econômico , Dióxido de Carbono/análise , Combustíveis Fósseis , Aquecimento Global , Humanos , Internacionalidade , Energia Renovável
3.
Environ Sci Pollut Res Int ; 29(35): 53584-53597, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35287193

RESUMO

The preponderance of emerging economies confronts significant trade-offs between economic growth and environmental sustainability considerations, and Turkey is no exception. This study draws strength from the United Nations Sustainable Development Goals (UN-SDGs-7,11,12 & 13). To this end, the present study explores the role of the environmental Kuznets curve (EKC) hypothesis for the case of Turkey for annual frequency data from 1970 to 2020. The present study leverages on the novel dynamic autoregressive-distributed lag (DARDL) methodology and Bayer and Hanck combined cointegration test. The combined Bayer and Hanck cointegration test alongside ARDL bounds test traces equilibrium relationship between economic growth, urbanization, FDI, energy use, and CO2 emission over the investigated period. Empirical results from the DARDL simulation analysis validates the EKC hypothesis. These results suggest that environmental quality is being compromised for economic growth at the earlier stage of economic growth (scale stage). The EKC phenomenon is affirmed as a 1% increase in economic growth increase emission level by 0.1580% and quadratic economic growth decrease emission by 0.1095% in the short and long run, respectively. Similarly, urbanization and energy used in both the short and long run also worsen environmental quality while FDI influx in the long run improves environmental quality in Turkey. These outcomes have far-reaching environment-urbanization growth implications. From a policy lens, the current study subscribed to the environmental stick policies and investment on strategies on a paradigm shift from fossil-fuel energy consumption base to renewables. Further insights are highlighted in the concluding section.


Assuntos
Dióxido de Carbono , Desenvolvimento Econômico , Dióxido de Carbono/análise , Internacionalidade , Investimentos em Saúde , Turquia
4.
Surv Geophys ; 40(4): 979-999, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31395994

RESUMO

Several upcoming satellite missions have core science requirements to produce data for accurate forest aboveground biomass mapping. Largely because of these mission datasets, the number of available biomass products is expected to greatly increase over the coming decade. Despite the recognized importance of biomass mapping for a wide range of science, policy and management applications, there remains no community accepted standard for satellite-based biomass map validation. The Committee on Earth Observing Satellites (CEOS) is developing a protocol to fill this need in advance of the next generation of biomass-relevant satellites, and this paper presents a review of biomass validation practices from a CEOS perspective. We outline the wide range of anticipated user requirements for product accuracy assessment and provide recommendations for the validation of biomass products. These recommendations include the collection of new, high-quality in situ data and the use of airborne lidar biomass maps as tools toward transparent multi-resolution validation. Adoption of community-vetted validation standards and practices will facilitate the uptake of the next generation of biomass products.

5.
Neuroimage Clin ; 23: 101858, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31128523

RESUMO

Parkinson's Disease (PD) and Multiple System Atrophy (MSA) are two parkinsonian syndromes that share many symptoms, albeit having very different prognosis. Although previous studies have proposed multimodal MRI protocols combined with multivariate analysis to discriminate between these two populations and healthy controls, studies combining all MRI indexes relevant for these disorders (i.e. grey matter volume, fractional anisotropy, mean diffusivity, iron deposition, brain activity at rest and brain connectivity) with a completely data-driven voxelwise analysis for discrimination are still lacking. In this study, we used such a complete MRI protocol and adapted a fully-data driven analysis pipeline to discriminate between these populations and a healthy controls (HC) group. The pipeline combined several feature selection and reduction steps to obtain interpretable models with a low number of discriminant features that can shed light onto the brain pathology of PD and MSA. Using this pipeline, we could discriminate between PD and HC (best accuracy = 0.78), MSA and HC (best accuracy = 0.94) and PD and MSA (best accuracy = 0.88). Moreover, we showed that indexes derived from resting-state fMRI alone could discriminate between PD and HC, while mean diffusivity in the cerebellum and the putamen alone could discriminate between MSA and HC. On the other hand, a more diverse set of indexes derived by multiple modalities was needed to discriminate between the two disorders. We showed that our pipeline was able to discriminate between distinct pathological populations while delivering sparse model that could be used to better understand the neural underpinning of the pathologies.


Assuntos
Encéfalo/diagnóstico por imagem , Interpretação de Imagem Assistida por Computador/métodos , Atrofia de Múltiplos Sistemas/diagnóstico por imagem , Neuroimagem/métodos , Doença de Parkinson/diagnóstico por imagem , Idoso , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Atrofia de Múltiplos Sistemas/patologia , Doença de Parkinson/patologia
6.
ACS Appl Mater Interfaces ; 11(2): 2218-2224, 2019 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-30582695

RESUMO

Graphene oxide (GO) is not only a unique class of two-dimensional (2D) materials but also an important precursor for scalable preparation of graphene. The efficient size fractionation of GO is of great importance to the fundamental and applied studies of chemically modified graphene, but remains a great challenge. Herein, we report an efficient and scalable fractionation method of GO employing reversible adsorption/desorption of temperature-responsive poly( N-isopropylacrylamide) on GO to amplify its mass difference and significantly improve the fractionation efficiency. Furthermore, size-dependent sodium ion storage of the resulting fractionated reduced GO (RGO) is revealed for the first time with high sodium storage performance achieved for the smallest RGO because of its largest d-spacing and most defect sites. This work provides valuable insights into the size fractionation and size-dependent electrochemical performance of graphene, which can be potentially extended to other 2D materials.

7.
ACS Nano ; 12(12): 12879-12887, 2018 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-30525431

RESUMO

Deliberate design of advantageous nanostructures holds great promise for developing high-performance electrode materials for electrochemical energy storage. However, it remains a tremendous challenge to simultaneously gain high gravimetric, areal, and volumetric capacities as well as high rate performance and cyclability to meet practical requirements mainly due to the intractable insufficient ion diffusion and limited active sites for dense electrodes with high areal mass loadings. Herein we report a double-holey-heterostructure framework, in which holey Fe2O3 nanosheets (H-Fe2O3) are tightly and conformably grown on the holey reduced graphene oxide (H-RGO). This hierarchical nanostructure allows for rapid ion and electron transport and sufficient utilization of active sites throughout a highly compact and thick electrode. Therefore, the free-standing flexible H-Fe2O3/H-RGO heterostructure anode can simultaneously deliver ultrahigh gravimetric, areal, and volumetric capacities of 1524 mAh g-1, 4.72 mAh cm-2, and 2621 mAh cm-3, respectively, at 0.2 A g-1 after 120 cycles, and extraordinary rate performance with a capacity of 487 mAh g-1 (1.51 mAh cm-2) at a high current density of 30 A g-1 (93 mA cm-2) as well as excellent cycling stability with a capacity retention of 96.3% after 1600 cycles, which has rarely been achieved before.

8.
Chem Sci ; 9(34): 7009-7016, 2018 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-30210776

RESUMO

Herein a novel and general microwave-assisted chemical vapor deposition (CVD)-like synthetic strategy was developed to realize the ultrafast synthesis of a series of well-dispersed monolayer/few-layer N-doped graphene shell encapsulated metal nanocrystals (M@NC) by using a metal-organic framework (MOF) on graphene as precursors for the first time. Unlike traditional programmed heat treatment, this microwave-assisted method decomposed the MOF into separated metal and carbon- and nitrogen-containing gases rather than aggregated metal and carbon composites during the initial thermal transformation stages. This change ensured the effective control of the subsequent formation process of carbon on the surface of metal and led to the formation of well-dispersed M@NC with monolayer/few-layer NC. Moreover, the graphene substrate promoted the full exposure of all active monolayer/few-layer NC, and thus the obtained FeNi@NC/graphene displays the best electrocatalytic properties for the oxygen evolution reaction of all of the previously reported M@NC based catalysts, including the lowest overpotential (261 mV) at 10 mA cm-2 in alkaline electrolyte (1 M KOH), the smallest Tafel slope (40 mV dec-1) and excellent durability for at least 120 h.

9.
ACS Appl Mater Interfaces ; 10(39): 33269-33275, 2018 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-30199222

RESUMO

In the past years, considerable efforts have been devoted to the deliberate synthesis of nanosulfur in various hosts with sophisticated structures to improve the performance of lithium-sulfur batteries (LSBs) and reveal the structure-property relationship. It is taken for granted that these elaborate sulfur nanostructures are well maintained in the ultimate electrode after the traditional mixing and coating method. Herein, we, for the first time, reveal the unexpected sulfur structure deterioration in nanosulfur/graphene composites during the electrode preparation using the traditional method because of the long-term neglected dissolution-recrystallization effect of sulfur in solvents. Consequently, compared with binder-free three-dimensional graphene/sulfur electrodes, the milled graphene/sulfur electrodes exhibit much worse electrochemical performance. On the basis of this, we further propose a facile and universal graphene oxide-assisted assembly method to avoid the dissolution-recrystallization of sulfur, by which binder-free three-dimensional ethylenediamine-functionalized graphene/sulfur (3DEFGS) electrodes have been successfully prepared. The 3DEFGS electrodes with a high areal sulfur loading of ∼6 mg cm-2 exhibit an ultrahigh initial capacity of 1394 mA h g-1 at 0.1 C, an excellent rate performance with a capacity of 796 mA h g-1 at 4 C, and superior long-term cycling stability (885 mA h g-1 after 500 cycles at 1 C), which are among the best performances achieved by all reported LSB cathodes with high areal sulfur loadings.

10.
Case Rep Gastrointest Med ; 2018: 6040693, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30159179

RESUMO

Considered to be rare, mucosal melanomas are rare type of melanoma that are found on mucosal surfaces and are primary or metastatic in origin. We report a case of a 66-year-old Hispanic female who presented with vague abdominal pain and upon further endoscopic work-up revealed 2 gastric lesions. Endoscopic biopsy results revealed gastric melanoma in the distal lesion. A PET/CT scan indicated it to be suspicious for the primary site of metastasis but was ultimately diagnosed as a benign nevus on biopsy. An extensive clinical exam showed no other probable sites of origin. The patient underwent a subtotal Billroth II gastrectomy and enterostomy tube placement for temporary feeding. Primary melanoma of the stomach is an exceptionally rare occurrence with limited cases that can be accounted for in literature; thus we report this case for review.

11.
Science ; 355(6328): 925-931, 2017 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-28254935

RESUMO

The extent to which pre-Columbian societies altered Amazonian landscapes is hotly debated. We performed a basin-wide analysis of pre-Columbian impacts on Amazonian forests by overlaying known archaeological sites in Amazonia with the distributions and abundances of 85 woody species domesticated by pre-Columbian peoples. Domesticated species are five times more likely than nondomesticated species to be hyperdominant. Across the basin, the relative abundance and richness of domesticated species increase in forests on and around archaeological sites. In southwestern and eastern Amazonia, distance to archaeological sites strongly influences the relative abundance and richness of domesticated species. Our analyses indicate that modern tree communities in Amazonia are structured to an important extent by a long history of plant domestication by Amazonian peoples.


Assuntos
Domesticação , Florestas , Árvores , Brasil , História Antiga , Humanos
12.
Nature ; 519(7541): 78-82, 2015 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-25739631

RESUMO

In 2005 and 2010 the Amazon basin experienced two strong droughts, driven by shifts in the tropical hydrological regime possibly associated with global climate change, as predicted by some global models. Tree mortality increased after the 2005 drought, and regional atmospheric inversion modelling showed basin-wide decreases in CO2 uptake in 2010 compared with 2011 (ref. 5). But the response of tropical forest carbon cycling to these droughts is not fully understood and there has been no detailed multi-site investigation in situ. Here we use several years of data from a network of thirteen 1-ha forest plots spread throughout South America, where each component of net primary production (NPP), autotrophic respiration and heterotrophic respiration is measured separately, to develop a better mechanistic understanding of the impact of the 2010 drought on the Amazon forest. We find that total NPP remained constant throughout the drought. However, towards the end of the drought, autotrophic respiration, especially in roots and stems, declined significantly compared with measurements in 2009 made in the absence of drought, with extended decreases in autotrophic respiration in the three driest plots. In the year after the drought, total NPP remained constant but the allocation of carbon shifted towards canopy NPP and away from fine-root NPP. Both leaf-level and plot-level measurements indicate that severe drought suppresses photosynthesis. Scaling these measurements to the entire Amazon basin with rainfall data, we estimate that drought suppressed Amazon-wide photosynthesis in 2010 by 0.38 petagrams of carbon (0.23-0.53 petagrams of carbon). Overall, we find that during this drought, instead of reducing total NPP, trees prioritized growth by reducing autotrophic respiration that was unrelated to growth. This suggests that trees decrease investment in tissue maintenance and defence, in line with eco-evolutionary theories that trees are competitively disadvantaged in the absence of growth. We propose that weakened maintenance and defence investment may, in turn, cause the increase in post-drought tree mortality observed at our plots.


Assuntos
Carbono/metabolismo , Secas , Florestas , Clima Tropical , Brasil , Dióxido de Carbono/metabolismo , Respiração Celular , Fotossíntese , Árvores/citologia , Árvores/metabolismo
13.
Nature ; 519(7543): 344-8, 2015 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-25788097

RESUMO

Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.


Assuntos
Dióxido de Carbono/análise , Sequestro de Carbono , Floresta Úmida , Atmosfera/química , Biomassa , Brasil , Carbono/análise , Carbono/metabolismo , Dióxido de Carbono/metabolismo , Caules de Planta/metabolismo , Árvores/crescimento & desenvolvimento , Árvores/metabolismo , Clima Tropical , Madeira/análise
14.
Cereb Cortex ; 25(9): 2670-82, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24706734

RESUMO

Huntington's disease (HD) is characterized by progressive motor impairment. Therefore, the connectivity of the corticospinal tract (CST), which is the main white matter (WM) pathway that conducts motor impulses from the primary motor cortex to the spinal cord, merits particular attention. WM abnormalities have already been shown in presymptomatic (Pre-HD) and symptomatic HD subjects using magnetic resonance imaging (MRI). In the present study, we examined CST microstructure using diffusion tensor imaging (DTI)-based tractography in 30-direction DTI data collected from 100 subjects: Pre-HD subjects (n = 25), HD patients (n = 25) and control subjects (n = 50), and T2*-weighted (iron sensitive) imaging. Results show decreased fractional anisotropy (FA) and increased axial (AD), and radial diffusivity (RD) in the bilateral CST of HD patients. Pre-HD subjects had elevated iron in the left CST, regionally localized between the brainstem and thalamus. CAG repeat length in conjunction with age, as well as motor (UHDRS) assessment were correlated with CST FA, AD, and RD both in Pre-HD and HD. In the presymptomatic phase, increased iron in the inferior portion supports the "dying back" hypothesis that axonal damage advances in a retrograde fashion. Furthermore, early iron alteration may cause a high level of toxicity, which may contribute to further damage.


Assuntos
Doença de Huntington/patologia , Córtex Motor/patologia , Tratos Piramidais/patologia , Medula Espinal/patologia , Adulto , Análise de Variância , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estatística como Assunto
15.
Hum Brain Mapp ; 35(7): 3143-51, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24895252

RESUMO

Increased iron in subcortical gray matter (GM) structures of patients with Huntington's disease (HD) has been suggested as a causal factor in neuronal degeneration. But how iron content is related to white matter (WM) changes in HD is still unknown. For example, it is not clear whether WM changes share the same physiopathology (i.e. iron accumulation) with GM or whether there is a different mechanism. The present study used MRI to examine iron content in premanifest gene carriers (PreHD, n = 25) and in early HD patients (n = 25) compared with healthy controls (n = 50). 3T MRI acquisitions included high resolution 3D T1, EPI sequences for diffusion tensor imaging (DTI) as an indirect measure of tissue integrity, and T2*-weighted gradient echo-planar imaging for MR-based relaxometry (R2*), which provides an indirect measure of ferritin/iron deposition in the brain. Myelin breakdown starts in the PreHD stage, but there is no difference in iron content values. Iron content reduction manifests later, in the early HD stage, in which we found a lower R2* parameter value in the isthmus. The WM iron reduction in HD is temporally well-defined (no iron differences in PreHD subjects and iron differences only in early HD patients). Iron level in callosal WM may be regarded as a marker of disease state, as iron does not differentiate PreHD subjects from controls but distinguishes between PreHD and HD.


Assuntos
Corpo Caloso/metabolismo , Doença de Huntington/patologia , Ferro/metabolismo , Bainha de Mielina/patologia , Adulto , Feminino , Humanos , Doença de Huntington/metabolismo , Imageamento Tridimensional , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Escalas de Graduação Psiquiátrica
16.
J Clin Microbiol ; 52(7): 2680-3, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24808242

RESUMO

Dientamoeba fragilis is a common enteropathogen of humans. Recently a cyst stage of the parasite was described in an animal model; however, no cyst stage has been described in detail from clinical samples. We describe both cyst and precystic forms from human clinical samples.


Assuntos
Dientamoeba/citologia , Dientamebíase/parasitologia , Esporos de Protozoários/citologia , Dientamoeba/fisiologia , Humanos , Microscopia , Esporos de Protozoários/fisiologia
17.
Nature ; 506(7486): 76-80, 2014 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-24499918

RESUMO

Feedbacks between land carbon pools and climate provide one of the largest sources of uncertainty in our predictions of global climate. Estimates of the sensitivity of the terrestrial carbon budget to climate anomalies in the tropics and the identification of the mechanisms responsible for feedback effects remain uncertain. The Amazon basin stores a vast amount of carbon, and has experienced increasingly higher temperatures and more frequent floods and droughts over the past two decades. Here we report seasonal and annual carbon balances across the Amazon basin, based on carbon dioxide and carbon monoxide measurements for the anomalously dry and wet years 2010 and 2011, respectively. We find that the Amazon basin lost 0.48 ± 0.18 petagrams of carbon per year (Pg C yr(-1)) during the dry year but was carbon neutral (0.06 ± 0.1 Pg C yr(-1)) during the wet year. Taking into account carbon losses from fire by using carbon monoxide measurements, we derived the basin net biome exchange (that is, the carbon flux between the non-burned forest and the atmosphere) revealing that during the dry year, vegetation was carbon neutral. During the wet year, vegetation was a net carbon sink of 0.25 ± 0.14 Pg C yr(-1), which is roughly consistent with the mean long-term intact-forest biomass sink of 0.39 ± 0.10 Pg C yr(-1) previously estimated from forest censuses. Observations from Amazonian forest plots suggest the suppression of photosynthesis during drought as the primary cause for the 2010 sink neutralization. Overall, our results suggest that moisture has an important role in determining the Amazonian carbon balance. If the recent trend of increasing precipitation extremes persists, the Amazon may become an increasing carbon source as a result of both emissions from fires and the suppression of net biome exchange by drought.


Assuntos
Atmosfera/química , Ciclo do Carbono , Secas/estatística & dados numéricos , Biomassa , Biota , Brasil , Dióxido de Carbono/análise , Monóxido de Carbono/análise , Incêndios/estatística & dados numéricos , Água Doce/análise , Fotossíntese , Chuva , Estações do Ano , Árvores/metabolismo , Clima Tropical
18.
Oecologia ; 174(1): 295-306, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24026500

RESUMO

Understanding climatic controls on tropical forest productivity is key to developing more reliable models for predicting how tropical biomes may respond to climate change. Currently there is no consensus on which factors control seasonal changes in tropical forest tree growth. This study reports the first comprehensive plot-level description of the seasonality of growth in a Peruvian tropical forest. We test whether seasonal and interannual variations in climate are correlated with changes in biomass increment, and whether such relationships differ among trees with different functional traits. We found that biomass increments, measured every 3 months on the two plots, were reduced by between 40 and 55% in the peak dry season (July-September) relative to peak wet season (January-March). The seasonal patterns of biomass accumulation are significantly (p < 0.01) associated with seasonal patterns of rainfall and soil water content; however, this may reflect a synchrony of seasonal cycles rather than direct physiological controls on tree growth rates. The strength of the growth seasonality response among trees is significantly correlated to functional traits: consistent with a hypothesised trade-off between maximum potential growth rate and hydraulic safety, tall and fast-growing trees with broad stems had the most strongly seasonal biomass accumulation, suggesting that they are more productive in the wet season, but more vulnerable to water limitation in the dry season.


Assuntos
Estações do Ano , Árvores/crescimento & desenvolvimento , Clima Tropical , Madeira , Biomassa , Ecossistema , Peru , Chuva , Solo , Água/fisiologia
20.
ScientificWorldJournal ; 2012: 308034, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22629128

RESUMO

Pseudomonas aeruginosa is an opportunistic pathogen in environmental waters with a high prevalence of multidrug resistance. In this study the synergistic efficacy of synergy antibiotic combinations in multidrug-resistant P. aeruginosa strains isolated from an abattoir effluent was investigated. Water samples were processed using membrane filtration; Pseudomonas was isolated with Pseudomonas Isolation Agar and confirmed using polymerase chain reaction with specie-specific primer. Susceptibility studies and in vitro synergy interaction testing were carried out, employing agar dilution and Etest procedure, respectively. Resistance was noted for clinically relevant antipseudomonal agents tested. Finding from antibiotic synergy interaction studies revealed that cefepime, imipenem, and meropenem combined with amikacin resulted in statistically significant (P < 0.0001) in vitro antibiotics synergy interaction, indicating the possible use of this regimen in treatment of pseudomonal infections.


Assuntos
Matadouros , Antibacterianos/administração & dosagem , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Resíduos Industriais , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/isolamento & purificação , Microbiologia da Água , Sobrevivência Celular/efeitos dos fármacos , Sinergismo Farmacológico , Pseudomonas aeruginosa/classificação
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