Climate change is expected to alter the geographic distribution of many plant species worldwide. However, there is still no clear evidence showing a generalised direction and magnitude of these ...distribution shifts. Here, we have surveyed, in nine mountainous regions in Spain, an array of tree species along entire elevational ranges, as surrogates of their global climatic ranges, to test for elevational shifts towards cooler locations. We analysed the distribution recruitment patterns of five dominant tree species, recording the abundance and measuring the primary growth of juveniles in 306 plots. Three of the species have a temperate-boreal distribution with populations at their southern edge in the Mediterranean mountain ranges: Pinus sylvestris, Pinus uncinata and Fagus sylvatica; and the other two species have a Mediterranean distribution: Quercus ilex and Pinus nigra. Despite the contrasting phylogenies and biogeographies, we identified a similar pattern in recruitment abundance across species, with an asymmetric distribution of juveniles (more recruits in the middle-upper elevation of their range), but higher annual growths at lower elevations. This survival-growth trade-off at the early recruitment stage may potentially counterbalance at population level the negative effect of global warming on recruit survival at the lower edge of species ranges. These findings suggest a demographic stabilisation process at the early recruitment stage of these tree species, and highlight the importance of considering the different demographic stages across the whole climatic range to understand the effects that climate change may exert on species distributions and population dynamics.
Issue Title: Special Issue: Meta-Learning Recent advances in meta-learning are providing the foundations to construct meta-learning assistants and task-adaptive learners. The goal of this special ...issue is to foster an interest in meta-learning by compiling representative work in the field. The contributions to this special issue provide strong insights into the construction of future meta-learning tools. In this introduction we present a common frame of reference to address work in meta-learning through the concept of meta-knowledge. We show how meta-learning can be simply defined as the process of exploiting knowledge about learning that enables us to understand and improve the performance of learning algorithms.PUBLICATION ABSTRACT
The concept of isohydry/anisohydry describes the degree to which plants regulate their water status, operating from isohydric with strict regulation to anisohydric with less regulation. Though some ...species level measures of isohydry/anisohydry exist at a few locations, ecosystem‐scale information is still largely unavailable. In this study, we use diurnal observations from active (Ku‐Band backscatter from QuikSCAT) and passive (X‐band vegetation optical depth (VOD) from Advanced Microwave Scanning Radiometer on EOS Aqua) microwave satellite data to estimate global ecosystem isohydry/anisohydry. Here diurnal observations from both satellites approximate predawn and midday plant canopy water contents, which are used to estimate isohydry/anisohydry. The two independent estimates from radar backscatter and VOD show reasonable agreement at low and middle latitudes but diverge at high latitudes. Grasslands, croplands, wetlands, and open shrublands are more anisohydric, whereas evergreen broadleaf and deciduous broadleaf forests are more isohydric. The direct validation with upscaled in situ species isohydry/anisohydry estimates indicates that the VOD‐based estimates have much better agreement than the backscatter‐based estimates. The indirect validation with prior knowledge suggests that both estimates are generally consistent in that vegetation water status of anisohydric ecosystems more closely tracks environmental fluctuations of water availability and demand than their isohydric counterparts. However, uncertainties still exist in the isohydry/anisohydry estimate, primarily arising from the remote sensing data and, to a lesser extent, from the methodology. The comprehensive assessment in this study can help us better understand the robustness, limitation, and uncertainties of the satellite‐derived isohydry/anisohydry estimates. The ecosystem isohydry/anisohydry has the potential to reveal new insights into spatiotemporal ecosystem response to droughts.
Key Points
Isohydry/anisohydry estimates from backscatter and VOD data show reasonable agreement at low and middle latitudes but diverge at high latitudes
Grasslands, croplands, and open shrublands are more anisohydric, while evergreen broadleaf and deciduous broadleaf forests are more isohydric
VOD‐based isohydry/anisohydry estimates show better agreement with upscaled in situ measurements than backscatter‐based estimates
In the investigated InAlN/GaN layers, it is shown that the surface morphology and the crystallinity of the alloy critically depend on the In composition. Atomic force microscopy analysis points out ...that step flow growth is not easily attained in this system. When the InAlN or AlN interlayer thickness is increased, the growth mode becomes three‐dimensional. However, the formed islands are hundred of nanometers apart, and were not observed in the transmission electron microscope.
Porous GaN polycrystalline layers with n-type conduction characteristics were catalytically grown from Mg films formed by decomposition of a Mg2N3 precursor typically employed for activating p-type ...conduction in GaN. After being exposed to oxygen, the Mg film oxidized to a polycrystalline high-κ oxide between the ohmic alloy interlayer contact and the porous GaN, while maintaining a clean interface. Electrical measurements on devices coupled to composition analysis and electron microscopy of the component layers confirm that a MOS-type porous GaN diode on silicon can be formed by chemical vapor deposition in a single growth regime.
Disaggregation in optical networks is particularly relevant to be considered for the deployment of 5G services and towards the support of 6G. Particularly in the metro area network (MAN), this is ...especially crucial, as is the adoption of suitable photonic technologies enabling dense integration to design a sustainable network architecture. Furthermore, to dynamically allocate the ever-increasing traffic, supporting multiterabit capacity, an optimal usage of the available resources by properly exploiting the multiple dimensions (including the spectral and spatial ones), with programmable and adaptive data plane solutions, is key. In this work, we assess the capabilities of a disaggregated MAN that relies on new photonic devices, node architectures, and sliceable bandwidth/bit-rate-variable transceivers, approaching wavelength division multiplexing and space division multiplexing. A hierarchical network topology is attained and the feasibility of a cross-hierarchy optical continuum is demonstrated. In fact, we experimentally demonstrate the successful transmission of multiterabits/second capacity across multiple nodes corresponding to different hierarchy levels that have different implementation schemes and support different technologies. For the top tier hierarchy level nodes, we demonstrate the transmission of up to {8} \times {11} = {88} spatial/spectral channels, for a total capacity of 1.676 Tb/s, employing a node architecture able to handle up to 2560 spatial/spectral channels at different aggregation levels and granularities.
To locate structural changes in the brain accounting for the increasing effectiveness in cognition and skills that occurs at the final stage of behavioral development, we attempted to determine the ...age at which the corpus callosum completes its active growth period. We assessed the growth rate of the corpus callosum by measuring its area twice on midsagittal magnetic resonance imaging scans separated by a 2-year interval, in a series of 90 subjects with a wide range of ages. We observed an increase in the size of the corpus callosum as long as human mentation expands, up to the middle 20s. Clinical and experimental data about the corpus callosum, together with the present findings, suggest that the corpus callosum is part of the highest order-latest maturing neural network of the brain.
En la actualidad, la tromboprofilaxis en cirugía de columna es motivo de estudio ya que a pesar de ser un evento poco frecuente, puede causar complicaciones graves. El objetivo del presente estudio ...es proponer un protocolo de prevención de eventos trombóticos en cirugía de columna por vía posterior que reduzca la aparición de estos eventos, ya sea en forma de trombosis venosa profunda o tromboembolismo pulmonar, limitando el número de pacientes en los que se emplea profilaxis farmacológica para intentar evitar la aparición de hematoma epidural.
Se estudió de manera retrospectiva a los 235 pacientes del centro a los que se les había practicado una cirugía de artrodesis de columna por vía posterior en los cinco años previos, encontrándose el protocolo en vigencia. En todos ellos se aplicaron medidas mecánicas de tromboprofilaxis, consistentes en medias de compresión y, en aquellos con factores de riesgo de trombosis, se aplicaron también medidas farmacológicas. En todos se inició la deambulación precoz tras la cirugía. Se recogieron variables demográficas, clínicas, quirúrgicas, así como las complicaciones aparecidas a lo largo del seguimiento que se realizaba al mes uno, dos, cuatro, seis y 12 tras la cirugía. Los eventos trombóticos, en caso de aparecer, se diagnosticaban mediante la clínica y pruebas de imagen, como la ecografía Doppler y el angioTAC.
De los 235 pacientes, 153 cumplieron con los criterios de inclusión del estudio. Aparecieron un total de cuatro eventos trombóticos, uno en forma de trombosis venosa profunda y tres en forma de tromboembolismo pulmonar, acabando estos últimos en éxitus. Ninguna de las variables estudiadas tuvo significación estadística para la aparición de evento trombótico. Estos pacientes estaban recibiendo medidas farmacológicas adicionales a las mecánicas por presentar factores de riesgo de trombosis.
Mediante la aplicación de dichas medidas se consigue realizar una adecuada prevención de eventos tromboembólicos en la población estudiada de pacientes intervenidos de cirugía de columna por vía posterior.
There is no generalized consensus regarding perioperative prophylaxis of venous thromboembolism (VTE), either on using or timing it in patients undergoing spine surgery. VTE is a current concern because, even though being an uncommon event, it can cause serious complications. The aim of the present study is to propose guidelines for the prevention of thrombotic events in posterior spinal surgery, either as deep vein thrombosis or pulmonary thromboembolism. If the number of patients getting prophylaxis drugs is reduced a subsequent reduction of the incidence of epidural hematoma can be expected.
A number of 235 patients who had undergone posterior spinal arthrodesis in the previous five years were studied. Mechanical thromboprophylaxis measures consisting of compression stockings were applied in all of them. Anticoagulant drugs were also applied whenever risk factors for thrombosis were observed. Early weight-bearing was resumed immediately after surgery. Demographic, clinical, and surgical variables were collected, as well as complications appearing during the follow-up period, that was scheduled at one, two, four, six and twelve months after the surgery. Thrombotic events, if present, were diagnosed by clinical and imaging tests such as ultrasound and CT angiography.
From the total 235 patients of this series, one hundred and fifty-three cases met the study inclusion criteria. A total of four thrombotic events appeared, one in the form of deep vein thrombosis and other three in the form of pulmonary thromboembolism. These last patients suffering an embolism died because of it. None of the variables studied had statistical significance for the occurrence of a thrombotic event. All four patients who suffered thrombotic events were receiving anticoagulant drugs, in addition to mechanical compression stockings, because of the presence of risk factors for thrombosis.
By applying the fore mentioned protocol, adequate prevention of thromboembolic events was achieved in this study population of patients undergoing posterior spinal surgery.
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