Spin-transfer switching and low-field precession in exchange-biased spin valve nano-pillars

Using a three-dimensional focused-ion beam lithography process we have fabricated nanopillar devices which show spin transfer torque switching at zero external magnetic fields. Under a small in-plane external bias field, a field-dependent peak in the differential resistance versus current is observed similar to that reported in asymmetrical nanopillar devices. This is interpreted as evidence for the low-field excitation of spin waves which in our case is attributed to a spin-scattering asymmetry enhanced by the IrMn exchange bias layer coupled to a relatively thin CoFe fixed layer.Comment: 11 pages, 4 figures. To appear in APL, April 200

Dexfenfluramine and the oestrogen-metabolizing enzyme CYP1B1 in the development of pulmonary arterial hypertension

<p>Aims: Pulmonary arterial hypertension (PAH) occurs more frequently in women than men. Oestrogen and the oestrogen-metabolising enzyme cytochrome P450 1B1 (CYP1B1) play a role in the development of PAH. Anorectic drugs such as dexfenfluramine (Dfen) have been associated with the development of PAH. Dfen mediates PAH via a serotonergic mechanism and we have shown serotonin to up-regulate expression of CYP1B1 in human pulmonary artery smooth muscle cells (PASMCs). Thus here we assess the role of CYP1B1 in the development of Dfen-induced PAH.</p> <p>Methods and results: Dfen (5 mg kg−1 day−1 PO for 28 days) increased right ventricular pressure and pulmonary vascular remodelling in female mice only. Mice dosed with Dfen showed increased whole lung expression of CYP1B1 and Dfen-induced PAH was ablated in CYP1B1−/− mice. In line with this, Dfen up-regulated expression of CYP1B1 in PASMCs from PAH patients (PAH-PASMCs) and Dfen-mediated proliferation of PAH-PASMCs was ablated by pharmacological inhibition of CYP1B1. Dfen increased expression of tryptophan hydroxylase 1 (Tph1; the rate-limiting enzyme in the synthesis of serotonin) in PAH-PASMCs and both Dfen-induced proliferation and Dfen-induced up-regulation of CYP1B1 were ablated by inhibition of Tph1. 17β-Oestradiol increased expression of both Tph1 and CYP1B1 in PAH-PASMCs, and Dfen and 17β-oestradiol had synergistic effects on proliferation of PAH-PASMCs. Finally, ovariectomy protected against Dfen-induced PAH in female mice.</p> <p>Conclusion: CYP1B1 is critical in the development of Dfen-induced PAH in mice in vivo and proliferation of PAH-PASMCs in vitro. CYP1B1 may provide a novel therapeutic target for PAH.</p&gt

Microclimate affects landscape level persistence in the British Lepidoptera

Microclimate has been known to drive variation in the distribution and abundance of insects for some time. Until recently however, quantification of microclimatic effects has been limited by computing constraints and the availability of fine-scale biological data. Here, we tested fine-scale patterns of persistence/extinction in butterflies and moths against two computed indices of microclimate derived from Digital Elevation Models: a summer solar index, representing fine-scale variation in temperature, and a topographic wetness index, representing fine-scale variation in moisture availability. We found evidence of microclimate effects on persistence in each of four 20 × 20 km British landscapes selected for study (the Brecks, the Broads, Dartmoor, and Exmoor). Broadly, local extinctions occurred more frequently in areas with higher minimum or maximum solar radiation input, while responses to wetness varied with landscape context. This negative response to solar radiation is consistent with a response to climatic warming, wherein grid squares with particularly high minimum or maximum insolation values provided an increasingly adverse microclimate as the climate warmed. The variable response to wetness in different landscapes may have reflected spatially variable trends in precipitation. We suggest that locations in the landscape featuring cooler minimum and/or maximum temperatures could act as refugia from climatic warming, and may therefore have a valuable role in adapting conservation to climatic change

A simple approach to forest structure classification using airborne laser scanning that can be adopted across bioregions

Reliable assessment of forest structural types (FSTs) aids sustainable forest management. We developed a methodology for the identification of FSTs using airborne laser scanning (ALS), and demonstrate its generality by applying it to forests from Boreal, Mediterranean and Atlantic biogeographical regions. First, hierarchal clustering analysis (HCA) was applied and clusters (FSTs) were determined in coniferous and deciduous forests using four forest structural variables obtained from forest inventory data – quadratic mean diameter (QMD), Gini coefficient (GC), basal area larger than mean (BALM) and density of stems (N) –. Then, classification and regression tree analysis (CART) were used to extract the empirical threshold values for discriminating those clusters. Based on the classification trees, GC and BALM were the most important variables in the identification of FSTs. Lower, medium and high values of GC and BALM characterize single storey FSTs, multi-layered FSTs and exponentially decreasing size distributions (reversed J), respectively. Within each of these main FST groups, we also identified young/mature and sparse/dense subtypes using QMD and N. Then we used similar structural predictors derived from ALS – maximum height (Max), L-coefficient of variation (Lcv), L-skewness (Lskew), and percentage of penetration (cover), – and a nearest neighbour method to predict the FSTs. We obtained a greater overall accuracy in deciduous forest (0.87) as compared to the coniferous forest (0.72). Our methodology proves the usefulness of ALS data for structural heterogeneity assessment of forests across biogeographical regions. Our simple two-tier approach to FST classification paves the way toward transnational assessments of forest structure across bioregions

Assessment of Asthma Management in Adult Patients: A Retrospective Case-Note review in a general practice

This study aimed to assess asthma management in a sample of adult patients in a general practice. A retrospective case-note review was conducted, involving 27 asthma patients in a general practice in England. The Asthma Quality Improvement tool informed the development of the data collection tool. The data were analysed statistically by the researcher using frequencies testing, using descriptive statistics. Twenty- one participants out of 27 were reviewed in the general practice in the last 12-months by their healthcare practitioner. All the components of an asthma review were assessed and recorded except the inhaler-technique for 11 participants and 66.7% were classed as having poorly-controlled asthma symptoms. Although the small sample size affected the generalisability of the findings, reviewing the medical records of each participant allowed the researcher to highlight issues with asthma management in the sample. This study found that asthma care in the participants requires improvement and highlighted areas that could be targeted to enhance asthma care. Asthma care could be enhanced by focusing on increasing asthma patients’ engagement with their annual asthma reviews, enhancing the provision of the asthma action plan and following a consistent approach for inhaler-technique check and recording of asthma review components. Finally, conducting multiple checks of asthma patients’ medical records might help to identify patients who need a review and support them to enhance their management of their asthma

Climate change refugia for the flora and fauna of England

A variety of evidence suggests that species have, in the past, been able to withstand the effects of climatic change in localised environments known as refugia, where specific environmental conditions acted as a buffer against broader-scale climatic changes. Therefore, an important question for conservation is whether refugia might exist under current and future anthropogenic climate change. If there are areas that are likely to remain relatively climatically stable and so enable species to persist despite climate change making surrounding areas unsuitable, identifying and protecting these places will be an important part of future conservation strategies. This report is part of a project that is investigating this question. The report was commissioned to identify the characteristics of potential refugia, to investigate evidence for the existence of contemporary refugia by analysing patterns of local persistence and disappearance of over 1000 species across a range of taxa, and to identify sites in England with the potential to function as refugia for different taxonomic groups at a range of spatial scales

Interacting effects of climate change and habitat fragmentation on drought-sensitive butterflies

Climate change is expected to increase the frequency of some climatic extremes. These may have drastic impacts on biodiversity, particularly if meteorological thresholds are crossed, leading to population collapses. Should this occur repeatedly, populations may be unable to recover, resulting in local extinctions. Comprehensive time series data on butterflies in Great Britain provide a rare opportunity to quantify population responses to both past severe drought and the interaction with habitat area and fragmentation. Here, we combine this knowledge with future projections from multiple climate models, for different Representative Concentration Pathways (RCPs), and for simultaneous modelled responses to different landscape characteristics. Under RCP8.5, which is associated with ‘business as usual’ emissions, widespread drought-sensitive butterfly population extinctions could occur as early as 2050. However, by managing landscapes and particularly reducing habitat fragmentation, the probability of persistence until mid-century improves from around zero to between 6 and 42% (95% confidence interval). Achieving persistence with a greater than 50% chance and right through to 2100 is possible only under both low climate change (RCP2.6) and semi-natural habitat restoration. Our data show that, for these drought-sensitive butterflies, persistence is achieved more effectively by restoring semi-natural landscapes to reduce fragmentation, rather than simply focusing on increasing habitat area, but this will only be successful in combination with substantial emission reductions

The effectiveness of protected areas in the conservation of species with changing geographical ranges

A cornerstone of conservation is the designation and management of protected areas (PAs): locations often under conservation management containing species of conservation concern, where some development and other detrimental influences are prevented or mitigated. However, the value of PAs for conserving biodiversity in the long term has been questioned given that species are changing their distributions in response to climatic change. There is a concern that PAs may become climatically unsuitable for those species that they were designated to protect, and may not be located appropriately to receive newly-colonizing species for which the climate is improving. In the present study, we analyze fine-scale distribution data from detailed resurveys of seven butterfly and 11 bird species in Great Britain aiming to examine any effect of PA designation in preventing extinctions and promoting colonizations. We found a positive effect of PA designation on species' persistence at trailing-edge warm range margins, although with a decreased magnitude at higher latitudes and altitudes. In addition, colonizations by range expanding species were more likely to occur on PAs even after altitude and latitude were taken into account. PAs will therefore remain an important strategy for conservation. The potential for PA management to mitigate the effects of climatic change for retracting species deserves further investigation

Jay Forrester

Jay Wright Forrester was an American engineer and management thinker. He founded System Dynamics, an approach based on computer modelling which arguably has done more than any other method to provide a practical and realistic analysis of change processes in systems. System Dynamics (SD) has been taken up across the world, initially by Forrester’s students and colleagues, but increasingly by a much wider community. It has had profound and influential applications in a range of fields, most prominently organisational management, urban planning and environmental policy. Forrester summed up his concerns and his understanding of SD in an ‘elevator pitch’ (a statement short enough to be spoken in an elevator ride) on an email list: System dynamics deals with how things change through time, which includes most of what most people find important. It uses computer simulation to take the knowledge we already have about details in the world around us and to show why our social and physical systems behave the way they do. System dynamics demonstrates how most of our own decision-making policies are the cause of the problems that we usually blame on others, and how to identify policies we can follow to improve our situation. (Forrester JW. System dynamics in the elevator. System-dynamics email list. https://www.ventanasystems.co.uk/forum/viewtopic.php?t=1787#p1964. Accessed 25 Sept 2019, 1997

Terrestrial and Freshwater Ecosystems and Their Services (Chapter 2)

Chapter 2, building on prior assessments1, provides a global assessment of the observed impacts and projected risks of climate change to terrestrial and freshwater ecosystems, including their component species and the services they provide to people. Where possible, differences among regions, taxonomic groups and ecosystem types are presented. Adaptation options to reduce risks to ecosystems and people are assessed