Why do trees adjust water relations and hydraulic architecture in response to nutrient availability?

Studies on water relations, hydraulic architecture and effects of nutrients on growth in trees have been studied for many years in relative isolation. Only recently the functional relations of these groups of plant traits have been investigated with a more integrative approach (e.g. Harvey and van den Driessche, 1999; Clearwater and Meinzer 2001: Ewers et al. 2000, 2001; Bucci et al. 2006; Hacke et al. 2010; Faustino et al. 2013). In this commentary we attempt to answer the question of why water relations and the hydraulic architecture of trees are functionally related with their nutrient availability. We will focus on results of studies where nutrient limitations have been removed or alleviated by additions of the two most important macronutrients: nitrogen and phosphorous.Fil: Goldstein, Guillermo Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología Funcional; Argentina. University of Miami. Departament of Biology; Estados UnidosFil: Bucci, Sandra Janet. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Scholz, Fabian Gustavo. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Comodoro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin

Exploring the Potential of Apple SensorKit and Digital Phenotyping Data as New Digital Biomarkers for Mental Health Research

The use of digital phenotyping continues to expand across all fields of health. By collecting quantitative data in real-time using devices such as smartphones or smartwatches, researchers and clinicians can develop a profile of a wide range of conditions. Smartphones contain sensors that collect data, such as GPS or accelerometer data, which can inform secondary metrics such as time spent at home, location entropy, or even sleep duration. These metrics, when used as digital biomarkers, are not only used to investigate the relationship between behavior and health symptoms but can also be used to support personalized and preventative care. Successful phenotyping requires consistent long-term collection of relevant and high-quality data. In this paper, we present the potential of newly available, for approved research, opt-in SensorKit sensors on iOS devices in improving the accuracy of digital phenotyping. We collected opt-in sensor data over 1 week from a single person with depression using the open-source mindLAMP app developed by the Division of Digital Psychiatry at Beth Israel Deaconess Medical Center. Five sensors from SensorKit were included. The names of the sensors, as listed in official documentation, include the following: phone usage, messages usage, visits, device usage, and ambient light. We compared data from these five new sensors from SensorKit to our current digital phenotyping data collection sensors to assess similarity and differences in both raw and processed data. We present sample data from all five of these new sensors. We also present sample data from current digital phenotyping sources and compare these data to SensorKit sensors when applicable. SensorKit offers great potential for health research. Many SensorKit sensors improve upon previously accessible features and produce data that appears clinically relevant. SensorKit sensors will likely play a substantial role in digital phenotyping. However, using these data requires advanced health app infrastructure and the ability to securely store high-frequency data

Technology use and attitudes towards digital mental health in people with severe mental health problems: a survey study in China

IntroductionDigital mental health is a promising solution to support people with severe mental health problems (SMI) in China. However, little is known about the ownership rate of digital technologies and attitudes towards utilising digital health technologies (DHTs) among people with SMI in the Chinese context. The aims of this study were to understand: (i) digital technology ownership and usage rate of people with SMI in China; (ii) attitudes toward DHTs in mental health services; and (iii) how the COVID-19 pandemic has influenced views on digital mental health.MethodsA cross-sectional survey was given to outpatients with SMI using the REDCap platform. To capture a diverse sample of people with SMI, the survey was distributed across psychiatric hospitals, general hospitals with a psychiatric unit, secondary hospitals, and community healthcare centres.ResultsIn total, 447 survey respondents completed the survey. Relative high ownership rates of digital technologies were found, with smartphone ownership (95.5%) and access to the internet (82.1%) being the highest technologies reported. However, less than half of respondents reported frequent health-related usage of digital technologies, which may be related to the lack of knowledge in using DHTs. Most respondents found DHTs being useful for access to mental health services during the pandemic and were willing to use DHTs after the pandemic.DiscussionOur data suggest that, despite the high ownership rate of digital technologies, training programmes to improve digital health literacy for people with SMI in China are necessary to realise the full potential of digital mental health

Variações em atributos biofísicos e fisiológicos em nível 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 nível de indivíduo 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 incluídas na análise, a fim de expandir os eixos de variação do ecossistema. Mudanças consistentes em atributos biofísicos em nível de parcela foram observadas ao longo do gradiente de densidade crescente de árvores. Estas incluíram uma diminuição na densidade média ponderada da madeira, aumentos na área foliar por planta, na condutividade hidráulica específica da folha, na área foliar específica e na condutância estomática. Um modelo conceitual das interações entre as características biofísicas, 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 mínimos de potencial hídrico 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 hídrico foliar estiveram associados com maior condutância estomática. Por outro lado, ao longo do gradiente de densidade arbórea, as variações em nível de parcela das características 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

“They Are Not Hard-to-Reach Clients. We Have Just Got Hard-to-Reach Services.” Staff Views of Digital Health Tools in Specialist Mental Health Services.

Background: Digital health products designed to help people with severe mental health problems appear to be feasible, acceptable, and efficacious. The challenge facing the digital mental health field is implementing digital tools in routine service delivery. To date, there has been a paucity of qualitative research exploring staff views of digital health solutions in the context of mental healthcare. Engaging and involving frontline staff in the design and rollout of new technology to improve utilization is imperative for successful uptake and adoption of digital tools. The aim of the current study is to explore frontline staff views regarding the utility and appropriateness of using digital tools in the healthcare pathway for people accessing specialist secondary care mental health services.Method: Qualitative study using framework analysis was used with 48 mental health staff working in early intervention for psychosis services. Six groups comprising 5–10 early intervention service staff members in each group were conducted across the Northwest of England. Robust measures were used to develop a stable framework, including member checking, triangulation, and consensus meetings.Results: Three themes were identified a priori: i) perceived barriers to adopting smartphone apps for early psychosis; ii) acceptability of digital health tools for early psychosis patients; and iii) data security, safety, and risk. Alongside exploring the a priori topics, one theme was generated a posteriori: iv) relationships.Conclusions: Staff working in specialist early intervention for psychosis services found digital tools on the whole acceptable in mental health service provision, but raised a number of concerns that will likely affect implementation of such systems into routine service delivery and practice. Thirteen recommendations are made in this paper as a result of the themes generated in these data. Implementing of digital systems needs to be simple and uncomplicated and improve clinical workflows for staff rather than hinder and increase clinical workflows. Furthermore, organizational support with a clear plan for implementing technological innovations is required for successful adoption of digital systems. Consideration of staff views around digital systems is important if successful adoption and implementation of such systems are to occur.Clinical Trial Registration: http://www.isrctn.com, identifier ISRCTN34966555

Relações hídricas e arquitetura hidráulica em árvores do cerrado : adequação às variações sazonais de disponibilidade hídrica 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 hídricos e de manter um balanço hídrico 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 hídrico 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 hídricas das árvores do Cerrado se ajustaram durante a estação seca para evitar o déficit hídrico crescente e assegurar a homeostase nos valores mínimos de potencial hídrico foliar ΨL e na perda total diária de água pela planta (iso-hidria). O comportamento iso-hídrico das árvores do Cerrado foi o resultado de uma diminuição da superfície foliar total por árvore, um forte controle estomático das perdas por evaporação, um aumento na condutividade hidráulica específica 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 críticos, 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