The mechanical stability of the world’s tallest broadleaf trees

© 2020 The Authors. Biotropica published by Wiley Periodicals LLC on behalf of Association for Tropical Biology and Conservation The factors that limit the maximum height of trees, whether ecophysiological or mechanical, are the subject of longstanding debate. Here, we examine the role of mechanical stability in limiting tree height and focus on trees from the tallest tropical forests on Earth, in Sabah, Malaysian Borneo, including the recently discovered tallest tropical tree, a 100.8 m Shorea faguetiana named Menara. We use terrestrial laser scans, in situ strain gauge data and finite element simulations, to map the architecture of tall tropical trees and monitor their response to wind loading. We demonstrate that a tree's risk of breaking due to gravity or self-weight decreases with tree height and is much more strongly affected by tree architecture than by material properties. In contrast, wind damage risk increases with tree height despite the larger diameters of tall trees, resulting in a U-shaped curve of mechanical risk with tree height. Our results suggest that the relative rarity of extreme wind speeds in north Borneo may be the reason it is home to the tallest trees in the tropics. Abstract in MALAY is available with online material

Multiple targets for flecainide action: implications for cardiac arrhythmogenesis

Flecainide suppresses cardiac tachyarrhythmias including paroxysmal atrial fibrillation, supraventricular tachycardia and arrhythmic long QT syndromes (LQTS), as well as the Ca(2+) -mediated, catecholaminergic polymorphic ventricular tachycardia (CPVT). However, flecainide can also exert pro-arrhythmic effects most notably following myocardial infarction and when used to diagnose Brugada syndrome (BrS). These divergent actions result from its physiological and pharmacological actions at multiple, interacting levels of cellular organization. These were studied in murine genetic models with modified Nav channel or intracellular ryanodine receptor (RyR2)-Ca(2+) channel function. Flecainide accesses its transmembrane Nav 1.5 channel binding site during activated, open, states producing a use-dependent antagonism. Closing either activation or inactivation gates traps flecainide within the pore. An early peak INa related to activation of Nav channels followed by rapid de-activation, drives action potential (AP) upstrokes and their propagation. This is diminished in pro-arrhythmic conditions reflecting loss of function of Nav 1.5 channels, such as BrS, accordingly exacerbated by flecainide challenge. Contrastingly, pro-arrhythmic effects attributed to prolonged AP recovery by abnormal late INaL following gain-of-function modifications of Nav 1.5 channels in LQTS3 are reduced by flecainide. Anti-arrhythmic effects of flecainide that reduce triggering in CPVT models mediated by sarcoplasmic reticular Ca(2+) release could arise from its primary actions on Nav channels indirectly decreasing [Ca(2+) ]i through a reduced [Na(+) ]i and/or direct open-state RyR2-Ca(2+) channel antagonism. The consequent [Ca(2+) ]i alterations could also modify AP propagation velocity and therefore arrhythmic substrate through its actions on Nav 1.5 channel function. This is consistent with the paradoxical differences between flecainide actions upon Na(+) currents, AP conduction and arrhythmogenesis under circumstances of normal and increased RyR2 function.S.C.S. and A.P.J. are funded by the British Heart Foundation (PG/14/79/31102). K.J. is funded by the Fundamental Research Grant Scheme (FRGS/2/2014/SKK01/PERDANA/ 02/1), Ministry of Education, Malaysia and the Research Support Fund, Faculty of Health and Medical Science, University of Surrey. A.F.D. is funded by the National Health and Medical Research Council (NHMRC) of Australia (APP1126201). A.J.T. is funded by the British Heart Foundation (PG/13/39/3029). C.L.H.H. is funded by the Medical Research Council (MR/M001288/1), Wellcome Trust (105727/Z/14/Z), British Heart Foundation (PG/14/79/ 31102), the McVeigh Benefaction and SADS UK

Oxide Heterostructures from a Realistic Many-Body Perspective

Oxide heterostructures are a new class of materials by design, that open the possibility for engineering challenging electronic properties, in particular correlation effects beyond an effective single-particle description. This short review tries to highlight some of the demanding aspects and questions, motivated by the goal to describe the encountered physics from first principles. The state-of-the-art methodology to approach realistic many-body effects in strongly correlated oxides, the combination of density functional theory with dynamical mean-field theory, will be briefly introduced. Discussed examples deal with prominent Mott-band- and band-band-insulating type of oxide heterostructures, where different electronic characteristics may be stabilized within a single architectured oxide material.Comment: 19 pages, 9 figure

STAMINA: Stochastic Approximate Model-Checker for Infinite-State Analysis

Stochastic model checking is a technique for analyzing systems that possess probabilistic characteristics. However, its scalability is limited as probabilistic models of real-world applications typically have very large or infinite state space. This paper presents a new infinite state CTMC model checker, STAMINA, with improved scalability. It uses a novel state space approximation method to reduce large and possibly infinite state CTMC models to finite state representations that are amenable to existing stochastic model checkers. It is integrated with a new property-guided state expansion approach that improves the analysis accuracy. Demonstration of the tool on several benchmark examples shows promising results in terms of analysis efficiency and accuracy compared with a state-of-the-art CTMC model checker that deploys a similar approximation method

Evolutionary connectionism: algorithmic principles underlying the evolution of biological organisation in evo-devo, evo-eco and evolutionary transitions

The mechanisms of variation, selection and inheritance, on which evolution by natural selection depends, are not fixed over evolutionary time. Current evolutionary biology is increasingly focussed on understanding how the evolution of developmental organisations modifies the distribution of phenotypic variation, the evolution of ecological relationships modifies the selective environment, and the evolution of reproductive relationships modifies the heritability of the evolutionary unit. The major transitions in evolution, in particular, involve radical changes in developmental, ecological and reproductive organisations that instantiate variation, selection and inheritance at a higher level of biological organisation. However, current evolutionary theory is poorly equipped to describe how these organisations change over evolutionary time and especially how that results in adaptive complexes at successive scales of organisation (the key problem is that evolution is self-referential, i.e. the products of evolution change the parameters of the evolutionary process). Here we first reinterpret the central open questions in these domains from a perspective that emphasises the common underlying themes. We then synthesise the findings from a developing body of work that is building a new theoretical approach to these questions by converting well-understood theory and results from models of cognitive learning. Specifically, connectionist models of memory and learning demonstrate how simple incremental mechanisms, adjusting the relationships between individually-simple components, can produce organisations that exhibit complex system-level behaviours and improve the adaptive capabilities of the system. We use the term “evolutionary connectionism” to recognise that, by functionally equivalent processes, natural selection acting on the relationships within and between evolutionary entities can result in organisations that produce complex system-level behaviours in evolutionary systems and modify the adaptive capabilities of natural selection over time. We review the evidence supporting the functional equivalences between the domains of learning and of evolution, and discuss the potential for this to resolve conceptual problems in our understanding of the evolution of developmental, ecological and reproductive organisations and, in particular, the major evolutionary transitions

Weight management interventions in adults with intellectual disabilities and obesity: a systematic review of the evidence

o evaluate the clinical effectiveness of weight management interventions in adults with intellectual disabilities (ID) and obesity using recommendations from current clinical guidelines for the first line management of obesity in adults. Full papers on lifestyle modification interventions published between 1982 to 2011 were sought by searching the Medline, Embase, PsycINFO and CINAHL databases. Studies were evaluated based on 1) intervention components, 2) methodology, 3) attrition rate 4) reported weight loss and 5) duration of follow up. Twenty two studies met the inclusion criteria. The interventions were classified according to inclusion of the following components: behaviour change alone, behaviour change plus physical activity, dietary advice or physical activity alone, dietary plus physical activity advice and multi-component (all three components). The majority of the studies had the same methodological limitations: no sample size justification, small heterogeneous samples, no information on randomisation methodologies. Eight studies were classified as multi-component interventions, of which one study used a 600 kilocalorie (2510 kilojoule) daily energy deficit diet. Study durations were mostly below the duration recommended in clinical guidelines and varied widely. No study included an exercise program promoting 225–300 minutes or more of moderate intensity physical activity per week but the majority of the studies used the same behaviour change techniques. Three studies reported clinically significant weight loss (≥ 5%) at six months post intervention. Current data indicate weight management interventions in those with ID differ from recommended practice and further studies to examine the effectiveness of multi-component weight management interventions for adults with ID and obesity are justified

Prospective blind comparative clinical study of two point fixation of zygomatic complex fracture using wire and mini plates

<p>Abstract</p> <p>Background</p> <p>The zygomatic maxillary complex (ZMC) fractures are one of the most frequent injuries of the facial skeleton due to its position and facial contour. Assaults, road traffic accidents and falls are the principal etiologic factors that may cause fractures of zygomatic bone. The different fixation methods are applied to treat the zygomatic bone fractures, with many more classifications which have been described in the literature for the ease of management. The type of the fracture, its severity and associated facial fractures usually interferes the treatment modality.</p> <p>Purpose of study</p> <p>The aim of this paper is to show the results of 18yrs prospective blind comparative study using wire and plate osteosynthesis which needed open reduction and internal fixation involving Type II to Type IV Spissel and Schroll ZMC fractures.</p> <p>Materials and methods</p> <p>Total 80 cases included in the study out of 1780 ZMC cases which were treated using wire and plate osteosynthesis over a period of 18 yrs, involving only Type II to Type IV Spissel and Schroll ZMC fractures. Other types excluded from study to prevent observer bias. All the fixations carried out through Standard Dingman's incision using stainless steel 26 gauze wire and titanium 1.5 mm mini plate system under general anesthesia by single maxillofacial surgeon and evaluated by another maxillofacial surgeon who is blinded for surgical procedure after 2 and 4 wks of follow-up for facial symmetry, wound healing, functional assessment (mouth opening, diplopia), and sensory disturbance. All the data tabulated in Excel software (Microsoft) for statistical analysis. P-value calculated to know the Significance of treatment modality in all aspects.</p> <p>Results</p> <p>Result shows no significant p-values indicating both the operating techniques are equally efficient in the surgical management of ZMC fracture.</p> <p>Conclusion</p> <p>Osteosynthesis by mini plates is simple, logical and effective treatment compared to wire osteosynthesis in regard to stability of fracture fragments. Wire osteosynthesis will be helpful in emergency surgeries or where the mini plates are not available. Even though the wire osteosynthesis is economical compared to mini plate fixation; but the time and skill is required for fixation of wires.</p

Global and local concerns: What attitudes and beliefs motivate farmers to mitigate and adapt to climate change?

In response to agriculture\u27s vulnerability and contribution to climate change, many governments are developing initiatives that promote the adoption of mitigation and adaptation practices among farmers. Since most climate policies affecting agriculture rely on voluntary efforts by individual farmers, success requires a sound understanding of the factors that motivate farmers to change practices. Recent evidence suggests that past experience with the effects of climate change and the psychological distance associated with people\u27s concern for global and local impacts can influence environmental behavior. Here we surveyed farmers in a representative rural county in California\u27s Central Valley to examine how their intention to adopt mitigation and adaptation practices is influenced by previous climate experiences and their global and local concerns about climate change. Perceived changes in water availability had significant effects on farmers\u27 intention to adopt mitigation and adaptation strategies, which were mediated through global and local concerns respectively. This suggests that mitigation is largely motivated by psychologically distant concerns and beliefs about climate change, while adaptation is driven by psychologically proximate concerns for local impacts. This match between attitudes and behaviors according to the psychological distance at which they are cognitively construed indicates that policy and outreach initiatives may benefit by framing climate impacts and behavioral goals concordantly; either in a global context for mitigation or a local context for adaptation