Zonobiomes, zonoecotones and azonal vegetation along the Pacific coast of North America

In this study of the Pacific coast of North America, from Baja California to Alaska, we evaluated the hypothesis that the floristic composition of azonal vegetation determines areas and distribution limits similar to those of the corresponding zonobiomes (ZB), and does so in response to the same macroclimatic changes occurring on the continental scale. To this end, 686 vascular plants of the different habitats found in 279 sites along this coastal strip were recorded. Using an objective classification system (Average Linkage Clustering) and factorial analysis, floristic data acquired in fieldwork were classified into groups, which were in turn related to regional macroclimates. Our main finding was that the azonal coastal vegetation follows a distribution model that is closely linked to the corresponding macroclimate. The four ZB of the northern Pacific coast show a flora and azonal vegetation characteristic to each zonobiome; the latitudinal limits of the azonal vegetation practically coinciding with those already established for the zonal vegetation. The Boreal and Temperate ZB show high percentages of broadly distributed elements. The floristically richest zonobiome in terms of endemic taxa is the Mediterranean zonobiome, whereas the flora of Baja California is characterized by a high number of taxa related to Neotropical flora, especially to those showing links with South America. Data on the geographical distribution and habitats of the 247 most significant coastal species are also provided.     

The effects of climate change and land‐use change on demographic rates and population viability

Understanding the processes that lead to species extinctions is vital for lessening pressures on biodiversity. While species diversity, presence and abundance are most commonly used to measure the effects of human pressures, demographic responses give a more proximal indication of how pressures affect population viability and contribute to extinction risk. We reviewed how demographic rates are affected by the major anthropogenic pressures, changed landscape condition caused by human land use, and climate change. We synthesized the results of 147 empirical studies to compare the relative effect size of climate and landscape condition on birth, death, immigration and emigration rates in plant and animal populations. While changed landscape condition is recognized as the major driver of species declines and losses worldwide, we found that, on average, climate variables had equally strong effects on demographic rates in plant and animal populations. This is significant given that the pressures of climate change will continue to intensify in coming decades. The effects of climate change on some populations may be underestimated because changes in climate conditions during critical windows of species life cycles may have disproportionate effects on demographic rates. The combined pressures of land‐use change and climate change may result in species declines and extinctions occurring faster than otherwise predicted, particularly if their effects are multiplicative.     

Functional ultrasound imaging of the brain

We present functional ultrasound (fUS), a method for imaging transient changes in blood volume in the whole brain at better spatiotemporal resolution than with other functional brain imaging modalities. fUS uses plane-wave illumination at high frame rate and can measure blood volumes in smaller vessels than previous ultrasound methods. fUS identifies regions of brain activation and was used to image whisker-evoked cortical and thalamic responses and the propagation of epileptiform seizures in the rat brain.     

‘Ecologically complex carbon’– linking biodiversity values,carbon storage and habitat structure in some austral temperate forests

Aim We assessed how avian biodiversity and above‐ground carbon storage were related in different forest age‐classes, including mature stands (> 100 years), in a managed, mixed‐species eucalypt forest. Location Gippsland, south‐eastern Australia. Methods In 50 2‐ha stands ranging in age from ≤ 5 years to mature stands > 100 years, we undertook repeated avian surveys, performed detailed habitat measurements and estimated amounts of above‐ground carbon. Extensive wildfire reduced the number of sites to 28 (seven in each of four age classes) upon which analyses and inferences were made. We also analysed data on carbon storage and some bird responses from previously published studies. Results Mature vegetation (> 100 years) had the greatest richness, abundance and biomass of birds. Key ecological resources, such as tree‐hollows for nesting, generally occurred mostly in stands > 60 years. Avian richness per unit of above‐ground carbon storage was relatively low for stands of 20–60 years. While above‐ground carbon storage appeared to increase in a monotonic fashion as stands age and mature, there were quantum increases in all measures of avian biodiversity in mature stands (> 100 years). Main conclusions Our results suggest that carbon is organized in a different way, with substantially greater biodiversity benefits, in very old stands. Mature vegetation simultaneously maximizes both avian biodiversity and above‐ground carbon storage. These results bolster arguments for allocating highest priorities to the preservation of old‐growth forest stands rather than alternative investments (e.g. reafforestation for carbon sequestration).     

Engaging neuroscience to advance translational research in brain barrier biology

The delivery of many potentially therapeutic and diagnostic compounds to specific areas of the brain is restricted by brain barriers, of which the most well known are the blood-brain barrier (BBB) and the blood-cerebrospinal fluid (CSF) barrier. Recent studies have shown numerous additional roles of these barriers, including an involvement in neurodevelopment, in the control of cerebral blood flow, and--when barrier integrity is impaired--in the pathology of many common CNS disorders such as Alzheimer's disease, Parkinson's disease and stroke.     

Models of cardiac electromechanics based on individual hearts imaging data Image-based electromechanical models of the heart

Current multi-scale computational models of ventricular electromechanics describe the full process of cardiac contraction on both the micro- and macro- scales including: the depolarization of cardiac cells, the release of calcium from intracellular stores, tension generation by cardiac myofilaments, and mechanical contraction of the whole heart. Such models are used to reveal basic mechanisms of cardiac contraction as well as the mechanisms of cardiac dysfunction in disease conditions. In this paper, we present a methodology to construct finite element electromechanical models of ventricular contraction with anatomically accurate ventricular geometry based on magnetic resonance and diffusion tensor magnetic resonance imaging of the heart. The electromechanical model couples detailed representations of the cardiac cell membrane, cardiac myofilament dynamics, electrical impulse propagation, ventricular contraction, and circulation to simulate the electrical and mechanical activity of the ventricles. The utility of the model is demonstrated in an example simulation of contraction during sinus rhythm using a model of the normal canine ventricles.     

Module-based multiscale simulation of angiogenesis in skeletal muscle

Background  

Mathematical modeling of angiogenesis has been gaining momentum as a means to shed new light on the biological complexity underlying blood vessel growth. A variety of computational models have been developed, each focusing on different aspects of the angiogenesis process and occurring at different biological scales, ranging from the molecular to the tissue levels. Integration of models at different scales is a challenging and currently unsolved problem.