690 research outputs found
The Development of a Depression Preventive Intervention for Adolescents with Attention-Deficit/Hyperactivity Disorder
Despite the considerable progress made identifying attention-deficit/hyperactivity disorder (ADHD) as a risk for depressive outcomes in adolescence and adulthood as well as potential explanations for the co-occurrence of ADHD and unipolar depression (i.e., emotion regulation, family support, and reward responsivity), targeted depression prevention efforts have not yet been implemented for adolescents with ADHD. Thus, the specific aims were as follows: (1) develop a behaviorally oriented, tailored, depression preventive intervention for adolescents with ADHD targeting variables empirically supported to account for the covariation between ADHD and depression (Behaviorally Enhancing Adolescents’ Mood; BEAM), (2) pilot BEAM in a small sample of adolescents with ADHD and their parents, (3) evaluate the feasibility and acceptability of BEAM, and (4) examine preliminary results regarding changes in depressive symptoms, emotion regulation, reward responsivity, and family support after BEAM.
The sample consisted of 8 parent-adolescent dyads with adolescents ranging in age from 12 to 16 years old. Research questions were tested using both quantitative and qualitative methods. Outcome trends were evaluated using paired samples t-tests and reliable change indices. Semi-structured interviews were coded and analyzed qualitatively using NVivo10.
Group-level analyses indicated that there were significant differences in depressive symptoms, emotion regulation, and reward responsivity after BEAM. Findings on family support after BEAM were equivocal. According to reliable change indices used to analyze individual results, majority of participants saw improvements in depressive symptoms and emotion regulation. In addition to improvements in outcome variables, both parents and adolescents were highly satisfied with the BEAM program and used BEAM skills following the completion of the program. Though staff supervision notes suggested that several barriers for delivery of the program arose, the BEAM program was easy to implement and was done so with high integrity.
The study’s main findings and their clinical implications are further discussed, including suggested revisions to the BEAM program. Future directions for research are presented with a focus on moving towards a large, randomized control trial
Water uptake and transport in lianas and co-occurring trees of a seasonally dry tropical forest
Water uptake and transport were studied in eight liana species in a seasonally dry tropical forest on Barro Colorado Island, Panama. Stable hydrogen isotope composition (δD) of xylem and soil water, soil volumetric water content (θv), and basal sap flow were measured during the 1997 and 1998 dry seasons. Sap flow of several neighboring trees was measured to assess differences between lianas and trees in magnitudes and patterns of daily sap flow. Little seasonal change in θv was observed at 90–120 cm depth in both years. Mean soil water δD during the dry season was −19‰ at 0–30 cm, −34‰ at 30–60 cm, and −50‰ at 90–120 cm. Average values of xylem δD among the liana species ranged from –28‰ to –44‰ during the middle of the dry season, suggesting that water uptake was restricted to intermediate soil layers (30–60 cm). By the end of the dry season, all species exhibited more negative xylem δD values (–41‰ to –62‰), suggesting that they shifted to deeper water sources. Maximum sap flux density in co-occurring lianas and trees were comparable at similar stem diameter (DBH). Furthermore, lianas and trees conformed to the same linear relationship between daily sap flow and DBH. Our observations that lianas tap shallow sources of soil water at the beginning of the dry season and that sap flow is similar in lianas and trees of equivalent stem diameter do not support the common assumptions that lianas rely primarily on deep soil water and that they have higher rates of sap flow than co-occurring trees of similar stem size
Variações em atributos biofÃsicos e fisiológicos em nÃvel de individuo e de parcela ao longo de um gradiente de densidade arbórea no Cerrado
O objetivo deste estudo foi caracterizar e compreender as variações morfológicas e
fisiológicas em atributos relacionados à economia da água, em nÃvel de indivÃduo e de parcela, que ocorrem ao longo de
um gradiente de densidade arbórea em uma savana neotropical (cerrado). Parcelas de vegetação de cerrado submetidas
a um experimento de adubação de longo prazo e matas de galeria também foram incluÃdas na análise, a fim de expandir os
eixos de variação do ecossistema. Mudanças consistentes em atributos biofÃsicos em nÃvel de parcela foram observadas
ao longo do gradiente de densidade crescente de árvores. Estas incluÃram uma diminuição na densidade média
ponderada da madeira, aumentos na área foliar por planta, na condutividade hidráulica especÃfica da folha, na área foliar
especÃfica e na condutância estomática. Um modelo conceitual das interações entre as caracterÃsticas biofÃsicas,
morfológicas e fisiológicas foi desenvolvido em uma tentativa de explicar os determinantes da arquitetura hidráulica e
variações na economia de água de árvores do Cerrado. Consistente com o modelo, os valores mÃnimos de potencial hÃdrico durante a estação seca foram maiores nas árvores de baixa densidade de madeira, em comparação com árvores de alta
densidade de madeira, enquanto os maiores valores de potencial hÃdrico foliar estiveram associados com maior condutância
estomática. Por outro lado, ao longo do gradiente de densidade arbórea, as variações em nÃvel de parcela das caracterÃsticas
morfológicas e fisiológicas não puderam ser explicadas por variações de um único fator ambiental. Alguns dos fatores
contribuintes potenciais são: maior concentração e disponibilidade de nutrientes do solo na porção superior do gradiente de
densidade arbórea onde há um maior número de árvores e restrições no estabelecimento e crescimento pela inundação
periódica e pela presença de concreções no perfil do solo onde a densidade de árvores é mais baixa.The objective of this study was to characterize and understand morphological and physiological variation in traits
related to water economy, at the plant and stand level, along a gradient of tree density in a Neotropical savanna
(Cerrado). Cerrado plots subjected to long-term fertilization and gallery forests were also included in the analysis to
expand the axes of ecosystem variation. Consistent changes in stand level biophysical traits observed along the
gradient of increasing tree density included a decrease in weighted-average wood density, and increases in leaf surface
area per plant, leaf specific hydraulic conductivity, specific leaf area and stomatal conductance. A conceptual model of
biophysical, morphological and physiological trait interactions was developed in an attempt to explain determinants of
hydraulic architecture and variations in water economy of Cerrado trees. Consistent with the model minimum leaf water
potentials were higher, during the dry season, in low wood density trees compared to high wood density trees, and
higher leaf water potential was associated with higher stomatal conductance. On the other hand, variations in stand
level physiological and morphological traits along the tree density gradient could not be explained by variations in
single environmental factors. Some of the potential contributing factors are: higher concentration and availability of soil
nutrients in the upper portion of the gradient where tree density is greatest and constrains to tree establishment and
growth by waterlogging and presence of concretions in the soil profile where tree density is lowest
Relações hÃdricas e arquitetura hidráulica em árvores do cerrado : adequação à s variações sazonais de disponibilidade hÃdrica e de demanda evaporativa
O objetivo deste estudo foi determinar os ajustamentos na morfologia e fisiologia que
permitem árvores das savanas neotropicais do Brasil Central (Cerrado) de evitar déficits hÃdricos e de manter um balanço
hÃdrico interno praticamente constante apesar das variações sazonais da precipitação e no déficit de saturação do ar (D).
A precipitação na área de estudo é fortemente sazonal, com cerca de cinco meses praticamente sem chuva durante os
quais D é duas vezes maior aos valores medidos na época chuvosa. Como conseqüência da flutuação sazonal das
chuvas e de D, o potencial hÃdrico do solo muda substancialmente, nos primeiros 100 cm do solo, mas permanece quase constante abaixo de 2 m de profundidade. A arquitetura hidráulica e os parâmetros relacionados a relações hÃdricas das
árvores do Cerrado se ajustaram durante a estação seca para evitar o déficit hÃdrico crescente e assegurar a homeostase
nos valores mÃnimos de potencial hÃdrico foliar ΨL e na perda total diária de água pela planta (iso-hidria). O
comportamento iso-hÃdrico das árvores do Cerrado foi o resultado de uma diminuição da superfÃcie foliar total por
árvore, um forte controle estomático das perdas por evaporação, um aumento na condutividade hidráulica especÃfica da
folha e na condutância hidráulica foliar e um aumento da quantidade de águas retirada dos reservatórios internos do
caule, durante a estação seca. A eficiência no transporte de água aumentou, nas mesmas proporções, nas folhas e nos
ramos terminais durante a estação seca. Todos estes ajustamentos sazonais foram importantes para a manutenção de ΨL
acima de limiares crÃticos, com isto contribuindo para uma redução na formação de embolismos nos ramos e ajudando a
evitar a perda de turgor em tecidos foliares durante a época seca. Esses ajustes permitem que os ramos das espécies
lenhosas do Cerrado operem bem distanciados do ponto de disfunção catastrófica para a cavitação, enquanto as folhas
operam próximas e sofrem embolismos em uma base diária, especialmente durante a estação seca.We determined adjustments in physiology and morphology that allow Neotropical savanna trees from central Brazil (Cerrado)
to avoid water deficits and to maintain a nearly constant internal water balance despite seasonal changes in precipitation and
air saturation deficit (D). Precipitation in the study area is highly seasonal with about five nearly rainless months during which
D is two fold higher compared to wet season values. As a consequence of the seasonal fluctuations in rainfall and D, soil water
potential changes substantially in the upper 100 cm of soil, but remains nearly constant below 2 m depth. Hydraulic
architecture and water relations traits of Cerrado trees adjusted during the dry season to prevent increasing water deficits and
insure homeostasis in minimum leaf water potential ΨL and in total daily water loss per plant (isohydry). The isohydric
behavior of Cerrado trees was the result of a decrease in total leaf surface area per tree, a strong stomatal control of
evaporative losses, an increase in leaf-specific hydraulic conductivity and leaf hydraulic conductance and an increase in the
amount of water withdrawn from internal stem storage, during the dry season. Water transport efficiency increased in the same
proportion in leaves and terminal stems during the dry season. All of these seasonal adjustments were important for
maintaining ΨL above critical thresholds, which reduces the rate of embolism formation in stems and help to avoid turgor loss
in leaf tissues still during the dry season. These adjustments allow the stems of most Cerrado woody species to operate far
from the point of catastrophic dysfunction for cavitation, while leaves operate close to it and experience embolism on a daily
basis, especially during the dry season
Carbon Isotope Discrimination, Gas Exchange, and Growth of Sugarcane Cultivars under Salinity
Statistical analysis plan for the COMPARE trial: a 3-arm randomised controlled trial comparing the effectiveness of Constraint-induced Aphasia Therapy Plus and Multi-modality Aphasia Therapy to usual care in chronic post-stroke aphasia (COMPARE)
BackgroundWhile high-quality meta-analyses have confirmed the effectiveness of aphasia therapy after stroke, there is limited evidence for the comparative effectiveness of different aphasia interventions. Two commonly used interventions, Constraint-induced Aphasia Therapy Plus (CIAT Plus) and Multi-modality Aphasia Therapy (M-MAT), are hypothesised to rely on diverse underlying neural mechanisms for recovery and may be differentially responsive to aphasia severity. COMPARE is a prospective randomised open-blinded end-point trial designed to determine whether, in people with chronic post-stroke aphasia living in the community, CIAT Plus and M-MAT provide greater therapeutic benefit compared to usual care, are differentially effective according to aphasia severity, and are cost-effective. This paper details the statistical analysis plan for the COMPARE trial developed prior to data analysis.MethodsParticipants (n = 216) are randomised to one of three arms, CIAT Plus, M-MAT or usual care, and undertake therapy with a study trained speech pathologist in groups of three participants stratified by aphasia severity. Therapy occurs for 3 h blocks per day for 10 days across 2 weeks. The primary clinical outcome is aphasia severity as measured by the Western Aphasia Battery-Revised Aphasia Quotient (WAB-R-AQ) immediately post intervention. Secondary outcomes include WAB-R-AQ at 12-week follow-up, and functional communication, discourse efficiency, multimodal communication, and health-related quality of life immediately post intervention and at 12-week follow-up.ResultsLinear mixed models (LMMs) will be used to analyse differences between M-MAT and UC, and CIAT-Plus and UC on each outcome measure immediately and at 12 weeks post-intervention. The LMM for WAB-R-AQ will assess the differences in efficacy between M-MAT and CIAT-Plus. All analyses will control for baseline aphasia severity (fixed effect) and for the clustering effect of treatment groups (random effect).DiscussionThis trial will provide relative effectiveness data for two common interventions for people with chronic post-stroke aphasia, and highlight possible differential effects based on aphasia severity. Together with the health economic analysis data, the results will enable more informed personalised prescription for aphasia therapy after stroke.Trial registrationAustralian New Zealand Clinical Trials Registry: ACTRN 12615000618550 . Registered on 15 June 2016
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Reduced wood stiffness and strength, and altered stem form, in young antisense 4CL transgenic poplars with reduced lignin contents
• Reduced lignin content in perennial crops has been sought as a means to
improve biomass processability for paper and biofuels production, but it is unclear
how this could affect wood properties and tree form.
• Here, we studied a nontransgenic control and 14 transgenic events containing
an antisense 4-coumarate:coenzyme A ligase (4CL) to discern the consequences of
lignin reduction in poplar (Populus sp.). During the second year of growth, trees
were grown either free-standing in a field trial or affixed to stakes in a glasshouse.
• Reductions in lignin of up to 40% gave comparable losses in wood strength and
stiffness. This occurred despite the fact that low-lignin trees had a similar wood
density and up to three-fold more tension wood. In free-standing and staked trees,
the control line had twice the height for a given diameter as did low-lignin trees.
Staked trees had twice the height for a given diameter as free-standing trees in the
field, but did not differ in wood stiffness.
• Variation in tree morphogenesis appears to be governed by lignin · environment
interactions mediated by stresses exerted on developing cells. Therefore our
results underline the importance of field studies for assessing the performance of
transgenic trees with modified wood properties.Keywords: tension wood, lignin, stem form, wood strength, buckling safety factor, transgenic poplar, wood stiffnes
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An Annual Pattern of Native Embolism in Upper Branches of Four Tall Conifer Species
Premise of the study: The Pacific Northwest of North America experiences relatively mild winters and dry summers. For the
tall coniferous trees that grow in this region, we predicted that loss in the hydraulic conductivity of uppermost branches would
be avoided because of difficulty reversing accumulated emboli in xylem that is always under negative pressure.
• Methods: To test this hypothesis, we measured native percent loss in hydraulic conductivity (PLC; the decrease of in situ hydraulic
conductivity relative to the maximum) monthly throughout 2009 in branches at the tops (~50 m) of four species in an
old growth forest in southern Washington.
• Key results: Contrary to our prediction, freeze – thaw cycles resulted in considerable native PLC. Branches showed hydraulic
recovery in the spring and after a moderate increase in native embolism that was observed after an unusually hot period in
August. The September recovery occurred despite decreases in the leaf and stem water potentials compared to August values.
• Conclusions: Recoveries in branches of these trees could not have occurred by raising the water potential enough to dissolve
bubbles simply by transporting water from roots and must have occurred either through water absorption through needles and/
or refilling under negative pressure. Excluding the August value, native embolism values correlated strongly with air temperature
of the preceding 10 d. For three species, we found that branches with lower wood density had higher specific conductivity,
but not greater native PLC than branches with higher wood density, which calls into question whether there is any hydraulic
benefit to higher wood density in small branches in those species.Keywords: Tsuga heterophylla, Abies grandis, wood density, hydraulic conductivity, Thuja plicata, Pseudotsuga menziesi
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Coordination of leaf structure and gas exchange along a height gradient in a tall conifer
The gravitational component of water potential and frictional resistance during transpiration lead to substantial reductions in leaf water potential (Ψl) near the tops of tall trees, which can influence both leaf growth and physiology. We examined the relationships between morphological features and gas exchange in foliage collected near the tops of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees of different height classes ranging from 5 to 55 m. This sampling allowed us to investigate the effects of tree height on leaf structural characteristics in the absence of potentially confounding factors such as irradiance, temperature, relative humidity and branch length. The use of cut foliage for measurement of intrinsic gas-exchange characteristics allowed identification of height-related trends without the immediate influences of path length and gravity. Stomatal density, needle length, needle width and needle area declined with increasing tree height by 0.70 mm−2 m−1, 0.20 mm m−1, 5.9 × 10−3 mm m−1 and 0.012 mm2 m−1, respectively. Needle thickness and mesophyll thickness increased with tree height by 4.8 × 10−2 mm m−1 and 0.74 μm m−1, respectively. Mesophyll conductance (gm) and CO2 assimilation in ambient [CO2] (Aamb) decreased by 1.1 mmol m−2 s−1 per m and 0.082 μmol m−2 s−1 per m increase in height, respectively. Mean reductions in gm and Aamb of foliage from 5 to 55 m were 47% and 42%, respectively. The observed trend in Aamb was associated with gm and several leaf anatomic characteristics that are likely to be determined by the prevailing vertical tension gradient during foliar development. A linear increase in foliar δ13C values with height (0.042‰ m−1) implied that relative stomatal and mesophyll limitations of photosynthesis in intact shoots increased with height. These data suggest that increasing height leads to both fixed structural constraints on leaf gas exchange and dynamic constraints related to prevailing stomatal behavior.Keywords: leaf anatomy, mesophyll resistance, photosynthesis, growth limitationKeywords: leaf anatomy, mesophyll resistance, photosynthesis, growth limitatio
An Umbrella Review of Aphasia Intervention descriPtion In Research: the AsPIRE project
Background: Recent reviews conclude that aphasia intervention is effective. However, replication and implementation require detailed reporting of intervention is and a specification of participant profiles. To date, reviews concentrate more on efficacy than on intervention reporting quality.
Aims : The aim of this project is to review the descriptions of aphasia interventions and participants appearing in recent systematic reviews of aphasia intervention effectiveness. The relationship between the quality of these descriptions and the robustness of research design is explored, and the replicability of aphasia interventions is evaluated.
Methods and Procedures : The scope of our search was an analysis of the aphasia intervention studies included in the and EBRSR 2018 systematic reviews, and in the RCSLT 2014 literature synthesis. Intervention descriptions published separately from the intervention study (i.e. published online, in clinical tools, or a separate trial protocols) were not included. The criteria for inclusion were that participants had aphasia, the intervention involved language and/or communication, and included the following research designs: Randomised Controlled Trial (RCT), comparison or control, crossover design, case series. Exclusion criteria included non-SLT interventions, studies involving fewer than four participants, conference abstracts, studies not available in English. Studies were evaluated for completeness of intervention description using the TIDieR Checklist. Additionally, we rated the quality of patient and intervention description, with particular reference to replicability.
Outcomes and Results: Ninety-three studies were included. Only 14 studies (15%) had >50 participants. Fifty-six studies (60%) did not select participants with a specific aphasia profile, and a further 10 studies only described participants as non-fluent. Across the studies, an average of eight (of 12) TIDieR checklist items were given but information on where, tailoring, modification and fidelity items was rarely available. Studies that evaluated general aphasia intervention approaches tended to use RCT designs, whereas more specific intervention studies were more likely to use case series designs.
Conclusions: Group studies were generally under-powered and there was a paucity of research looking at specific aphasia interventions for specific aphasia profiles. There was a trade-off between the robustness of the design and the level of specificity of the intervention described. While the TIDieR framework is a useful guide to information which should be included in an intervention study, it is insufficiently sensitive for assessing replicability. We consider possible solutions to the challenges of making large-scale trials more useful for determining effective aphasia intervention
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