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1.
Front Immunol ; 15: 1400575, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38903505

RESUMO

A diagnosis of dermatomyositis requires recognition of distinct patterns of skin disease in combination with, and sometimes without, muscle weakness. Often, a striking contrast between involved and uninvolved areas is observed. Familiar patterns include eyelid and midfacial eruptions, Gottron papules/sign, and upper back (shawl sign), central chest (V/open collar sign), and lateral thigh (holster sign) involvement. More recently, new specific antibody/phenotype-associated patterns have been reported. We describe a case series of two distinct patterns of skin involvement in six adult patients with both classical and amyopathic dermatomyositis. Three had paraneoplastic disease. All had intermediate to richly pigmented skin; five were of Afro-Caribbean and one was of Asian-Caribbean descent. Four were men, and two were women. Ages ranged from 41 to 89 years. All patients had concomitant hallmark signs (facial, hand, and/or trunk signs). Three were amyopathic. The first pattern involved a sharply demarcated, horizontally oriented hyperpigmented patch/thin plaque across the shoulders and upper chest, extending up the anterior neck. The second was the combination of the classical upper back shawl distribution with distinct mid-back sparing and diffuse involvement of the lower back. Named patterns help with the recognition of skin rashes in dermatomyositis. Based on the current lexicon describing items of apparel, we liken the first pattern to a "fur stole and turtleneck" sign and the latter to a "halter-back" or "reflected-shawl" sign. Biopsies revealed hyperkeratosis and interface dermatitis, often with epidermal atrophy, compatible with dermatomyositis. These patterns perhaps represent the coalescence of already well-described signs, photo-exacerbation, koebnerization, mechanical stretch, and other currently unclear factors contributing to patterning in dermatomyositis. Pattern distribution recognition is particularly valuable in individuals with richly pigmented skin who may lack typical violaceous erythema. The distinct demarcation led to the initial misdiagnosis of allergic contact dermatitis or other exogenous dermatitis in most of our patients. Further work involves evaluation of antibody phenotype and internal involvement associations. Limitations include lack of specific antibody panels and longitudinal follow-up data.


Assuntos
Dermatomiosite , Humanos , Dermatomiosite/diagnóstico , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Pele/patologia , Autoanticorpos/sangue , Autoanticorpos/imunologia
3.
Am J Emerg Med ; 81: 127-128, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38723364

RESUMO

Extended-release formulations of buprenorphine offer less frequent dosing, provide consistent medication delivery, and improve adherence for treatment of opioid use disorder (OUD). Although buprenorphine is a partial agonist with seemingly less precipitated withdrawal and easier initiation than full opioid agonists used for OUD, its use is not benign and understanding of the different extended-release formulations is necessary. We report a case of a patient that received a long-acting buprenorphine formulation (Sublocade®) administered subcutaneously that presented to the emergency department with tachycardia, hyperglycemia, elevated anion gap, and sustained nausea and vomiting refractory to pharmacotherapy requiring surgical removal of the buprenorphine depot for resolution of nausea and vomiting symptoms.


Assuntos
Buprenorfina , Preparações de Ação Retardada , Transtornos Relacionados ao Uso de Opioides , Humanos , Buprenorfina/administração & dosagem , Buprenorfina/efeitos adversos , Transtornos Relacionados ao Uso de Opioides/tratamento farmacológico , Masculino , Analgésicos Opioides/efeitos adversos , Analgésicos Opioides/administração & dosagem , Antagonistas de Entorpecentes/administração & dosagem , Antagonistas de Entorpecentes/uso terapêutico , Antagonistas de Entorpecentes/efeitos adversos , Adulto , Feminino , Vômito/induzido quimicamente , Vômito/tratamento farmacológico , Náusea/induzido quimicamente , Náusea/tratamento farmacológico
5.
Brain Inform ; 10(1): 14, 2023 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-37341863

RESUMO

Virtual reality exposure therapy (VRET) is a novel intervention technique that allows individuals to experience anxiety-evoking stimuli in a safe environment, recognise specific triggers and gradually increase their exposure to perceived threats. Public-speaking anxiety (PSA) is a prevalent form of social anxiety, characterised by stressful arousal and anxiety generated when presenting to an audience. In self-guided VRET, participants can gradually increase their tolerance to exposure and reduce anxiety-induced arousal and PSA over time. However, creating such a VR environment and determining physiological indices of anxiety-induced arousal or distress is an open challenge. Environment modelling, character creation and animation, psychological state determination and the use of machine learning (ML) models for anxiety or stress detection are equally important, and multi-disciplinary expertise is required. In this work, we have explored a series of ML models with publicly available data sets (using electroencephalogram and heart rate variability) to predict arousal states. If we can detect anxiety-induced arousal, we can trigger calming activities to allow individuals to cope with and overcome distress. Here, we discuss the means of effective selection of ML models and parameters in arousal detection. We propose a pipeline to overcome the model selection problem with different parameter settings in the context of virtual reality exposure therapy. This pipeline can be extended to other domains of interest where arousal detection is crucial. Finally, we have implemented a biofeedback framework for VRET where we successfully provided feedback as a form of heart rate and brain laterality index from our acquired multimodal data for psychological intervention to overcome anxiety.

6.
Ecol Appl ; 33(5): e2858, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37084186

RESUMO

Emissions of methane (CH4 ) and nitrous oxide (N2 O) from soils to the atmosphere can offset the benefits of carbon sequestration for climate change mitigation. While past study has suggested that both CH4 and N2 O emissions from tidal freshwater forested wetlands (TFFW) are generally low, the impacts of coastal droughts and drought-induced saltwater intrusion on CH4 and N2 O emissions remain unclear. In this study, a process-driven biogeochemistry model, Tidal Freshwater Wetland DeNitrification-DeComposition (TFW-DNDC), was applied to examine the responses of CH4 and N2 O emissions to episodic drought-induced saltwater intrusion in TFFW along the Waccamaw River and Savannah River, USA. These sites encompass landscape gradients of both surface and porewater salinity as influenced by Atlantic Ocean tides superimposed on periodic droughts. Surprisingly, CH4 and N2 O emission responsiveness to coastal droughts and drought-induced saltwater intrusion varied greatly between river systems and among local geomorphologic settings. This reflected the complexity of wetland CH4 and N2 O emissions and suggests that simple linkages to salinity may not always be relevant, as non-linear relationships dominated our simulations. Along the Savannah River, N2 O emissions in the moderate-oligohaline tidal forest site tended to increase dramatically under the drought condition, while CH4 emission decreased. For the Waccamaw River, emissions of both CH4 and N2 O in the moderate-oligohaline tidal forest site tended to decrease under the drought condition, but the capacity of the moderate-oligohaline tidal forest to serve as a carbon sink was substantially reduced due to significant declines in net primary productivity and soil organic carbon sequestration rates as salinity killed the dominant freshwater vegetation. These changes in fluxes of CH4 and N2 O reflect crucial synergistic effects of soil salinity and water level on C and N dynamics in TFFW due to drought-induced seawater intrusion.


Assuntos
Óxido Nitroso , Áreas Alagadas , Solo/química , Metano , Carbono , Florestas , Dióxido de Carbono/análise
7.
Ecol Appl ; 32(8): e2700, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-35751513

RESUMO

Tidal freshwater forested wetlands (TFFW) provide critical ecosystem services including an essential habitat for a variety of wildlife species and significant carbon sinks for atmospheric carbon dioxide. However, large uncertainties remain concerning the impacts of climate change on the magnitude and variability of carbon fluxes and storage across a range of TFFW. In this study, we developed a process-driven Tidal Freshwater Wetlands DeNitrification-DeComposition model (TFW-DNDC) that has integrated new features, such as soil salinity effects on plant productivity and soil organic matter decomposition to explore carbon dynamics in the TFFW in response to drought-induced saltwater intrusion. Eight sites along the floodplains of the Waccamaw River (USA) and the Savannah River (USA) were selected to represent the TFFW transition from healthy to moderately and highly salt-impacted forests, and eventually to oligohaline marshes. The TFW-DNDC was calibrated and validated using field observed annual litterfall, stem growth, root growth, soil heterotrophic respiration, and soil organic carbon storage. Analyses indicate that plant productivity and soil carbon sequestration in TFFW could change substantially in response to increased soil pore water salinity and reduced soil water table due to drought, but in interactive ways dependent on the river simulated. These responses are variable due to nonlinear relationships between carbon cycling processes and environmental drivers. Plant productivity, plant respiration, soil organic carbon sequestration rate, and storage in the highly salt-impacted forest sites decreased significantly under drought conditions compared with normal conditions. Considering the high likelihood of healthy and moderately salt-impacted forests becoming highly salt-impacted forests under future climate change and sea-level rise, it is very likely that the TFFW will lose their capacity as carbon sinks without up-slope migration.


Assuntos
Salinidade , Áreas Alagadas , Ecossistema , Secas , Solo , Carbono , Florestas , Água Doce
8.
Front Cell Dev Biol ; 9: 750771, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34900996

RESUMO

Adhesion of basal keratinocytes to the underlying extracellular matrix (ECM) plays a key role in the control of skin homeostasis and response to injury. Integrin receptors indirectly link the ECM to the cell cytoskeleton through large protein complexes called focal adhesions (FA). FA also function as intracellular biochemical signaling platforms to enable cells to respond to changing extracellular cues. The α4ß1 and α9ß1 integrins are both expressed in basal keratinocytes, share some common ECM ligands, and have been shown to promote wound healing in vitro and in vivo. However, their roles in maintaining epidermal homeostasis and relative contributions to pathological processes in the skin remain unclear. We found that α4ß1 and α9ß1 occupied distinct regions in monolayers of a basal keratinocyte cell line (NEB-1). During collective cell migration (CCM), α4 and α9 integrins co-localized along the leading edge. Pharmacological inhibition of α4ß1 and α9ß1 integrins increased keratinocyte proliferation and induced a dramatic change in cytoskeletal remodeling and FA rearrangement, detrimentally affecting CCM. Further analysis revealed that α4ß1/α9ß1 integrins suppress extracellular signal-regulated kinase (ERK1/2) activity to control migration through the regulation of downstream kinases including Mitogen and Stress Activated Kinase 1 (MSK1). This work demonstrates the roles of α4ß1 and α9ß1 in regulating migration in response to damage cues.

9.
PLoS One ; 16(7): e0254408, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34242323

RESUMO

Coarse woody debris (CWD) is a significant component of the forest biomass pool; hence a model is warranted to predict CWD decomposition and its role in forest carbon (C) and nutrient cycling under varying management and climatic conditions. A process-based model, CWDDAT (Coarse Woody Debris Decomposition Assessment Tool) was calibrated and validated using data from the FACE (Free Air Carbon Dioxide Enrichment) Wood Decomposition Experiment utilizing pine (Pinus taeda), aspen (Populous tremuloides) and birch (Betula papyrifera) on nine Experimental Forests (EF) covering a range of climate, hydrology, and soil conditions across the continental USA. The model predictions were evaluated against measured FACE log mass loss over 6 years. Four widely applied metrics of model performance demonstrated that the CWDDAT model can accurately predict CWD decomposition. The R2 (squared Pearson's correlation coefficient) between the simulation and measurement was 0.80 for the model calibration and 0.82 for the model validation (P<0.01). The predicted mean mass loss from all logs was 5.4% lower than the measured mass loss and 1.4% lower than the calculated loss. The model was also used to assess the decomposition of mixed pine-hardwood CWD produced by Hurricane Hugo in 1989 on the Santee Experimental Forest in South Carolina, USA. The simulation reflected rapid CWD decomposition of the forest in this subtropical setting. The predicted dissolved organic carbon (DOC) derived from the CWD decomposition and incorporated into the mineral soil averaged 1.01 g C m-2 y-1 over the 30 years. The main agents for CWD mass loss were fungi (72.0%) and termites (24.5%), the remainder was attributed to a mix of other wood decomposers. These findings demonstrate the applicability of CWDDAT for large-scale assessments of CWD dynamics, and fine-scale considerations regarding the fate of CWD carbon.


Assuntos
Biomassa , Florestas , Madeira , Minerais , Pinus taeda
10.
PLoS One ; 16(6): e0251893, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34086700

RESUMO

Coarse woody debris (CWD) is an important component in forests, hosting a variety of organisms that have critical roles in nutrient cycling and carbon (C) storage. We developed a process-based model using literature, field observations, and expert knowledge to assess woody debris decomposition in forests and the movement of wood C into the soil and atmosphere. The sensitivity analysis was conducted against the primary ecological drivers (wood properties and ambient conditions) used as model inputs. The analysis used eighty-nine climate datasets from North America, from tropical (14.2° N) to boreal (65.0° N) zones, with large ranges in annual mean temperature (26.5°C in tropical to -11.8°C in boreal), annual precipitation (6,143 to 181 mm), annual snowfall (0 to 612 kg m-2), and altitude (3 to 2,824 m above mean see level). The sensitivity analysis showed that CWD decomposition was strongly affected by climate, geographical location and altitude, which together regulate the activity of both microbial and invertebrate wood-decomposers. CWD decomposition rate increased with increments in temperature and precipitation, but decreased with increases in latitude and altitude. CWD decomposition was also sensitive to wood size, density, position (standing vs downed), and tree species. The sensitivity analysis showed that fungi are the most important decomposers of woody debris, accounting for over 50% mass loss in nearly all climatic zones in North America. The model includes invertebrate decomposers, focusing mostly on termites, which can have an important role in CWD decomposition in tropical and some subtropical regions. The role of termites in woody debris decomposition varied widely, between 0 and 40%, from temperate areas to tropical regions. Woody debris decomposition rates simulated for eighty-nine locations in North America were within the published range of woody debris decomposition rates for regions in northern hemisphere from 1.6° N to 68.3° N and in Australia.


Assuntos
Madeira/química , Animais , Austrália , Carbono/química , Clima , Florestas , Fungos/química , Invertebrados/química , América do Norte , Solo/química , Temperatura , Árvores/química
11.
Vet Clin North Am Small Anim Pract ; 50(6): 1397-1409, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32981595

RESUMO

Viscoelastic testing, such as thromboelastography or thromboelastometry, is performed on whole-blood samples, which include both soluble plasma factors as well as blood cells and platelets bearing tissue factor and phospholipid. This methodology allows identification of fibrinolysis and can provide analysis of platelet function. Viscoelastic testing has become increasingly accessible and popular in emergency and critical care settings in recent years and can provide important information for the diagnosis and management of patients with hemostatic disorders. This article discusses the principles and interpretation of viscoelastic testing, application to small animal emergency and critical care medicine, and potential advantages and disadvantages.


Assuntos
Doenças do Gato/diagnóstico , Tromboelastografia/veterinária , Trombose Venosa/veterinária , Animais , Gatos , Doenças do Cão/diagnóstico , Cães , Hemostasia , Trombose Venosa/diagnóstico
12.
Opt Lett ; 45(11): 2977-2980, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32479437

RESUMO

In this Letter, we propose a new configuration for visible light communication systems, which results in doubling of the data rate due to the use of polarization division multiplexing. As light-emitting diodes are unpolarized incoherent light sources, we isolate both the perpendicular s and parallel p modes for independent modulation. For the first time, to the best of our knowledge, we show that it is possible to transmit and successfully recover two separate orthogonal frequency division multiplexing (OFDM) signals on each polarization (pol-OFDM). Furthermore, we compare the performance of the pol-OFDM system with the transmission of a single conventional OFDM signal without a polarizer over the same physical link. We show that similar bit error rates can be achieved while obtaining ∼45% improvement in both the data rate and spectral efficiency due to polarization multiplexing.

13.
Glycobiology ; 30(7): 454-462, 2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-31897478

RESUMO

Cells are covered with glycans. The expression and distribution of specific glycans on the surface of a cell are important for various cellular functions. Imaging these glycans is essential to aid elucidation of their biological roles. Here, utilizing methods of direct fluorescent glycan imaging, in which fluorescent sialic acids are directly incorporated into substrate glycans via recombinant sialyltranferases, we report the differential distribution of N- and O-glycans and variable expression of sialyl-T antigen on HeLa cells. While the expression of N-glycans tends to be more peripheral at positions where cell-cell interaction occurs, O-glycan expression is more granular but relatively evenly distributed on positive cells. While N-glycans are expressed on all cells, sialyl-T antigen expression exhibits a wide spectrum of variation with some cells being strongly positive and some cells being almost completely negative. The differential distribution of N- and O-glycans on cell surface reflects their distinctive roles in cell biology.


Assuntos
Antígenos Virais de Tumores/biossíntese , Imagem Óptica , Polissacarídeos/biossíntese , Ácidos Siálicos/biossíntese , Antígenos Virais de Tumores/química , Células HeLa , Humanos , Polissacarídeos/química , Ácidos Siálicos/química , Sialiltransferases/metabolismo
14.
Opt Lett ; 44(19): 4849-4852, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31568458

RESUMO

This Letter demonstrates, for the first time, to the best of our knowledge, a new wavelength-division multiplexing (WDM) scheme for visible light communications using multi-level colored pulse amplitude modulation. Unlike traditional WDM, no optical bandpass filters are required, and only a single optical detector is used. We show that, by transmitting n independent sets of weighted on-off keying non-return-to-zero data on separate wavelengths over a line-of-sight transmission path, the resultant additive symbols can be successfully demodulated. Hence, the data rates can be aggregated for a single user or divided into individual colors for multiple user access schemes. The system is empirically tested for M=4 and 8 using an off-the-shelf red, green, and blue (RGB) chip light-emitting diode (LED). We demonstrate that for M=4, using the R and B chips, a bit error rate (BER) of ≤10-6 can be achieved for each wavelength at bit rates up to 10 Mbps, limited by the LEDs under test. For M=8 using R, G, and B, a BER of ≤10-6 can be achieved for each wavelength at bit rates up to 5 Mbps.

15.
J Vet Emerg Crit Care (San Antonio) ; 29(5): 461-471, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31448558

RESUMO

OBJECTIVE: To review the pathophysiology, diagnostic approach, and treatment recommendations for hyponatremia in dogs and cats. ETIOLOGY: Hyponatremia almost always results from an increase in total body water (TBW), and not from loss of sodium. Abnormalities in antidiuretic hormone (ADH) are commonly part of the etiology of hyponatremia. DIAGNOSIS: Diagnosis of hyponatremia focuses on the cause of the increase of TBW. Assessment of the patient's volume status and measurement of urine sodium concentration are important factors. Measurement or calculated estimation of plasma osmolality can also guide the assessment of hyponatremia. THERAPY: Too rapid correction of serum sodium can precipitate osmotic demyelination syndrome. As a general rule, serum sodium concentration should be raised ≤10 mmol/L over 24 hours, but rapid increases in serum sodium are indicated if neurologic abnormalities are evident. Serum sodium can be increased using hypertonic saline, with dosing based on the patient's calculated sodium deficit. Treatment of the underlying cause of water ingestion or retention is also required to fully resolve hyponatremia. PROGNOSIS: Mortality rates are significantly higher in dogs and cats with hyponatremia compared to those with normal serum sodium concentrations, even in patients with mild hypontremia (<5 mmol/L below the lower value of the reference interval). Hyponatremia is also associated with increased risk of death if present during specific disease states in dogs.


Assuntos
Doenças do Gato/terapia , Doenças do Cão/terapia , Hiponatremia/veterinária , Solução Salina Hipertônica/uso terapêutico , Animais , Doenças do Gato/sangue , Gatos , Doenças do Cão/sangue , Cães , Esquema de Medicação/veterinária , Hiponatremia/terapia , Infusões Intravenosas/veterinária , Solução Salina Hipertônica/administração & dosagem , Sódio/sangue
16.
Glycobiology ; 29(11): 750-754, 2019 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-31361010

RESUMO

Glycosylation is a common modification found on numerous proteins and lipids. However, direct detection of glycans on these intact biomolecules has been challenge. Here, utilizing enzymatic incorporation of fluorophore-conjugated sialic acids, dubbed as direct fluorescent glycan labeling, we report the labeling and detection of N- and O-glycans on glycoproteins. The method allows detection of specific glycans without the laborious gel blotting and chemiluminescence reactions used in Western blotting. The method can also be used with a variety of fluorescent dyes.


Assuntos
Fluorescência , Polissacarídeos/análise , Sialiltransferases/química , Animais , Bovinos , Clostridium perfringens/enzimologia , Corantes Fluorescentes/química , Glicosilação , Humanos , Polissacarídeos/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Ácidos Siálicos/química , Ácidos Siálicos/metabolismo , Sialiltransferases/metabolismo
17.
Sensors (Basel) ; 19(15)2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31344813

RESUMO

The constructivist approach is interested in creating knowledge through active engagement and encourages students to build their knowledge from their experiences in the world. Learning through digital game making is a constructivist approach that allows students to learn by developing their own games, enhancing problem-solving skills and fostering creativity. In this context two tools, Create@School App and the Project Management Dashboard (PMD), were developed to enable students from different countries to be able to adapt their learning material by programming and designing games for their academic subjects, therefore integrating the game mechanics, dynamics, and aesthetics into the academic curriculum. This paper focuses on presenting the validation context as well as the evaluation of these tools. The Hassenzahl model and AttrakDiff survey were used for measuring users' experience and satisfaction, and for understanding emotional responses, thus providing information that enables testing of the acceptability and usability of the developed apps. After two years of usage of code-making apps (i.e., Create@School and its pre-design version Pocket Code), the pupils processed knowledge from their academic subjects spontaneously as game-based embedded knowledge. The students demonstrated creativity, a practical approach, and enthusiasm regarding making games focused on academic content that led them to learning, using mobile devices, sensors, images, and contextual information. This approach was widely accepted by students and teachers as part of their everyday class routines.

19.
J Vet Emerg Crit Care (San Antonio) ; 28(2): 168-172, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29485722

RESUMO

OBJECTIVE: Minimal data are available assessing the effect of acidemia on coagulation in dogs. The objective of this study was to assess the effect of in vitro acidification of canine blood on coagulation as measured via thromboelastography (TEG) and traditional tests of coagulation. We hypothesized that worsening acidemia would lead to progressive impairment on coagulation. DESIGN: Prospective study. SETTING: University teaching hospital. ANIMALS: Six client-owned dogs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Blood was collected into 3.2% sodium citrate vacutainer tubes. The pH of blood was adjusted from baseline using hydrochloric acid to create weak acidemia and strong acidemia. Coagulation was assessed using TEG, prothrombin time, and activated partial thromboplastin time. Kruskal-Wallis tests with Dunn's post hoc comparison tests were used to compare groups. Strong acidemia samples were significantly more acidic than baseline based on pH (P < 0.0005), HCO3- (P < 0.0062), pCO2 (P < 0.0001), and base excess (P < 0.0001). Using TEG, in vitro acidification of blood caused significant, progressive impairment of maximum amplitude (P = 0.0282) and alpha angle (P = 0.0312). Acidification of blood had no significant effect on prothrombin time (P = 0.345) or activated partial thromboplastin time (P = 0.944). CONCLUSIONS: In vitro acidification of canine whole blood results in hypocoagulability as measured by some TEG variables.


Assuntos
Testes de Coagulação Sanguínea/veterinária , Coagulação Sanguínea/efeitos dos fármacos , Cães/sangue , Animais , Feminino , Concentração de Íons de Hidrogênio , Masculino
20.
Ecology ; 99(2): 411-420, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29341107

RESUMO

Most forest ecosystems are simultaneously affected by concurrent global change drivers. However, when assessing these effects, studies have mainly focused on the responses to single factors and have rarely evaluated the joined effects of the multiple aspects of environmental change. Here, we analyzed the combined effects of anthropogenic nitrogen (N) deposition and climatic conditions on the radial growth of Acer saccharum, a dominant tree species in eastern North American forests. We capitalized on a long-term N deposition study, replicated along a latitudinal gradient, that has been taking place for more than 20 yr. We analyzed tree radial growth as a function of anthropogenic N deposition (ambient and experimental addition) and of summer temperature and soil water conditions. Our results reveal that experimental N deposition enhances radial growth of this species, an effect that was accentuated as temperature increased and soil water became more limiting. The spatial and temporal extent of our data also allowed us to assert that the positive effects of growing under the experimental N deposition are likely due to changes in the physiological performance of this species, and not due to the positive correlation between soil N and soil water holding capacity, as has been previously speculated in other studies. Our simulations of tree growth under forecasted climate scenarios specific for this region also revealed that although anthropogenic N deposition may enhance tree growth under a large array of environmental conditions, it will not mitigate the expected effects of growing under the considerably drier conditions characteristic of our most extreme climatic scenario.


Assuntos
Nitrogênio , Árvores , Mudança Climática , Ecossistema , Florestas
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