Search

SPECT and PET myocardial perfusion imaging (MPI) are widely used to evaluate patients for coronary artery disease. Regadenoson (a selective A2A adenosine receptor agonist) is a commonly used vasodilator agent for stress MPI because of its safety profile and ease of use. Common adverse reactions such as headache, shortness of breath, flushing, and chest and abdominal discomfort are typically mild and can be effectively reversed using methylxanthines such as aminophylline and caffeine. Neurological adverse reactions such as seizure and stroke have rarely been reported with the use of regadenoson. The hemodynamic changes associated with regadenoson administration, such as an exaggerated hypotensive or hypertensive response, may be the cause for the reported cerebrovascular accidents. Activation of central nervous system A2A adenosine receptors is thought to be responsible for seizure episodes in patients with or without known histories of seizure. A2A adenosine receptors activation is also believed to play a role in headaches and migraine. This patient reported who has a history of hemiplegic migraine developed left side weakness and headache following the administration of regadenoson during a PET MPI study. Imaging work-up to rule out cerebrovascular accident was normal. After 1 hour from the onset of his symptoms, his weakness and headache significantly improved with complete resolution within 24 hours. We concluded that regadenoson triggered a hemiplegic migraine episode in this patient, which has not been previously reported in the literature. It may be prudent to avoid regadenoson and adenosine use in patients with a history of hemiplegic migraine. [ABSTRACT FROM AUTHOR]

Background: Attenuation correction (AC) using hardware and software solutions has been shown to increase the specificity of SPECT MPI by decreasing false positive results and improving prognostic ability. Theoretically this should reduce downstream testing and unnecessary costs. We sought to assess the consequences of the use of Gd-153 scanning line source attenuation correction during SPECT myocardial perfusion imaging (MPI) on downstream invasive testing. Methods: All patients who underwent a clinically indicated Tc-99m stress SPECT MPI study from 2013 to 2015 at five hospitals (2 with AC and 3 without) were retrospectively reviewed. Patient demographics, results of testing, subsequent coronary angiography within 3 months, and revascularization were recorded. The results of the MPI studies, downstream angiogram utilization, and results of angiography were compared and a propensity matched subgroup analysis was performed. Results: A total of 9968 patients underwent SPECT MPI during the study time period (6106 performed with AC and 3862 without). Out of 3928 patients included in the propensity matched cohort, there was no difference in the proportion of abnormal MPI results between the two groups (31.5% vs 30.4%, P = 0.47), however, more patients underwent coronary angiography within 90 days in the AC group (10.6% vs 8.7%, P = 0.05). There was no significant difference in the proportion of patients with angiographically significant obstructive disease (53.4% vs 56.1%, P = 0.19), however, fewer patients in the AC group with obstructive coronary disease were revascularized (36.1% vs 46.8%, P = 0.04). The findings remained consistent after sub-group analysis in patients without known coronary disease. Conclusion: The use of scanning line source AC did not meaningfully influence the rate of abnormal MPI results or downstream invasive testing in this cohort. The clinical utility of scanning line source AC may be limited to facilitating stress-first imaging protocols. [ABSTRACT FROM AUTHOR]

The ISCHEMIA trial was a multicenter randomized controlled trial of 5,179 patients with stable coronary artery disease with moderate-to-severe ischemia comparing medical therapy versus medical therapy and revascularization. Because of this, careful consideration should be given to the management of the patient with moderate-to-severe ischemia on perfusion imaging seen in clinical practice as it is not clear that revascularization would not be beneficial for these patients with ISCHEMIA exclusion criteria. [Extracted from the article]

Geoconservation is an increasingly widely adopted theoretical, practical and administrative approach to the protection of geological and geomorphological features of special scientific, functional, historic, cultural, aesthetic, or ecological value. Protected sites on Earth include natural rocky outcrops, shorelines, river banks, and landscapes, as well as human-made structures such as road cuts and quarries exposing geological phenomena. However, geoconservation has rarely been discussed in the context of other rocky and icy planets, rings, moons, dwarf planets, asteroids, or comets, which present extraordinarily diverse, beautiful, and culturally, historically and scientifically important geological phenomena. Here we propose to adapt geoconservation strategies for protecting the geological heritage of these celestial bodies, and introduce the term ‘exogeoconservation’ and other associated terms for this purpose. We argue that exogeoconservation is acutely necessary for the scientific exploration and responsible stewardship of celestial bodies, and suggest how this might be achieved and managed by means of international protocols. We stress that such protocols must be sensitive to the needs of scientific, industrial, and other human activities, and not unduly prohibitive. However, with space exploration and exploitation likely to accelerate in coming decades, it is increasingly important that an internationally agreed, holistic framework be developed for the protection of our common ‘exogeoheritage’. [ABSTRACT FROM AUTHOR]

Coronary Artery Disease (CAD) remains the leading cause of death in the developed world. The advent of drug-eluting Bio-resorbable Stents (BRSs) heralded a significant development in the field of CAD, representing a step-change in the treatment paradigm and offering significant improvements in patient outcome. But, as noted by a Task Force sanctioned by the European Commission in 2017, their widespread clinical deployment has primarily been hampered by a lack of randomised clinical trial data demonstrating improved efficacy over traditional permanent drug-eluting stents (DESs). To date, only the Abbott BVS, voluntarily withdrawn from sale in 2017, has undergone such rigorous evaluation, and which showed inferior outcomes at 2–3 years. This timely review paper addresses leading BRS polymer stent technologies to highlight the trends in design strategies and current technological advancements aimed at overcoming such performance limitations. This review examines the leading BRS technologies to gauge the progression of polymer materials technology and strategies in this field. To highlight emerging trends with respect to constituent materials, the developmental history of each stent is discussed briefly, providing context to progress. Many stent features that relate to material selection including material types, material combinations, drugs, architecture features, strut thickness, processing techniques and radiopacity are considered and compared. Following detailed review of these stents, materials and related features are summarised and discussed to highlight the changing clinical needs, current targets and challenges ahead. [ABSTRACT FROM AUTHOR]

Fagus sylvatica (European beech) populations in Central Europe are currently expanding their dominance in many forest types. In this study we focused on the spatio-temporal dynamics of beech recruitment as a mechanism for successful expansion. Specifically we investigated: (1) the developmental trend of the tree community composition and spatial pattern in an unmanaged Picea abies-F. sylvatica forest over 37 years, (2) the pattern of decrease in clustering along increasing tree size gradient of beech, and (3) the spatial patterns of beech regeneration in relation to gap-makers. The study was conducted in the Žofín Forest Dynamics Plot, which is part to the Smithsonian Institution’s Forest Global Earth Observatory (ForestGEO) as the research plot representing European natural mixed temperate forests. To quantify these dynamics, we used the stem map of trees with DBH ⩾ 10 cm carried out in 1975, 1997, 2008 and a census of trees with DBH ⩾ 1 cm from 2012 to calculate recruitment, growth, mortality and, from those vital rates, population change. Various types of the pair correlation function were applied to the data to describe the tree density variability over time. Our analyses revealed a trend of increasing F. sylvatica representation at the expense of P. abies and Abies alba over the 37 years. Increased clustering of F. sylvatica trees with DBH ⩾ 10 cm correlated with new recruits at plots where F. sylvatica replaced declining P. abies . On the other hand, the decrease in F. sylvatica clustering at some plots was likely due to strong intra-specific competition. The analysis of the spatial patterns of F. sylvatica individuals along DBH gradient 1–9 cm showed a trend of increasing clustering up to 5 m distance. F. sylvatica saplings to 4 cm of DBH were positively spatially correlated with other conspecific individuals, although at larger sizes (DBH 7–9 cm), this relationship reversed to a negative correlation. Analysis of relationships between saplings and gap-makers did not reveal a clear pattern. We concluded that without a coarse-scale disturbance capable of restructuring the community, F. sylvatica will become the only dominant tree species in this forest type. F. sylvatica gradually replaces P. abies through its space occupation strategy because its recruits are already present before a canopy disturbance. Our results indicate that F. sylvatica saplings can grow up to 4 cm DBH under a closed canopy, but require a canopy disturbance to advance to a larger size class. [ABSTRACT FROM AUTHOR]

The structure of forest canopies correlates with stand maturity and biomass, and develops consistently over time. Remote-sensing technologies such as Light Detection and Ranging (LiDAR) have become prominent tools for measuring structural characteristics of forests. We walked a portable canopy LiDAR (PCL), an up-facing rangefinder that detects vegetation through the canopy at two kilohertz, along multiple transects at ten different forest stands in the area of Wytham Woods, Oxfordshire, UK. The stands had different species composition, were situated at forest edges and in forest core, were in fragments of different sizes and had different land-use histories. With these data we tested structural differences in vegetation across these stand types. Although none of the stands have been managed in the last 70 years, they have not converged structurally. Vertical canopy structure differed between stands that regrew naturally from open field and those with a history of coppice management. Forest stands that have developed following major fellings or through spread on to former grazing land showed some structural similarities to classic natural succession from large disturbances. Stands that were actively managed as coppice over preceding centuries, showed a similar structural pattern to mature forest, but without the tall overstorey that can develop into old growth communities. This structural divergence indicates two distinct pathways for secondary forests: with implications for the future biomass, stand structure, and species composition. The legacy of management practices can determine canopy structure decades after the forest is removed from active management, but can also be difficult to discern with remote sensing data. We recommend that “ground-truthing” remote sensing data go beyond traditional checks of height and topography, as the history and composition of secondary forests can have an important influence on the pace and compositional structure of recovery from management. [ABSTRACT FROM AUTHOR]

The shifting mosaic of patches in different phases of forest development is a widely used framework for describing stand dynamics, structure and biodiversity in European temperate forests. In spite of the common application of patch mapping of developmental stages/phases, an objective and quantified evaluation of patch mosaics has been missing. This approach identifies patches of forest stand according to a developmental trajectory, from Growth, through an Optimum stage to Breakdown. Here we present the first attempt to compare quantitative and qualitative characteristics of patch mosaics of stand developmental stages using three decades of extensive data in five study sites along a vegetation gradient. We do this using the same, observer independent method based on an artificial neural network classifier. We also used the historical stem position datasets to evaluate the change of mosaic characteristics in time. Resulting patch patterns were analyzed by standard mosaic metrics commonly used in landscape ecology, evaluating area, shape, aggregation and connectivity of patches. The mean patch size of the mosaic of four developmental stages showed a relatively narrow range of 570–800 m 2 in all study sites and censuses. The shape of patches in all sites and years had no significant differences, and the aggregation of patches of the same type was similar in all sites at the mosaic level. Conversely, we did find some stage-specific patterns. For example, the Growth stage was usually the most abundant (covering 25–50% of the stand), and had the highest mean patch size, ranging between 590 and 2800 m 2 . The Growth stage patches also had the most complex shapes. On the contrary, the Breakdown stage usually had the opposite values, forming constantly small (250–720 m 2 ), simple and scattered patches in the mosaic. These basic traits were found in all study sites and were stable in time. We also found some common trends in the dataset, such as increasing mean patch size of the Breakdown stage along the altitudinal vegetation gradient. The complex Steady State stage was generally more abundant than expected according to results of other studies and thus might indicate processes that have not been well described in previous, subjective, applications of the patch mosaic paradigm. [ABSTRACT FROM AUTHOR]

Background: Stress only SPECT myocardial perfusion imaging (MPI) is a validated strategy to streamline cardiac diagnostic imaging. The potential use of Rb82 PET stress only MPI has not been investigated. Methods and Results: Stress images from 200 Rb82 PET-MPI were reviewed by two blinded readers and categorized as not requiring additional rest images (normal) or requiring additional images (abnormal or equivocal). No additional images were deemed necessary for 95 (48%) and 99 (50%) by the two blinded readers. The stress only interpretation was compared to the previous read of the complete rest-stress study. The rate of detecting a normal result with stress only reading was 76%-79% with a negative predictive value of 94%-95%. Clinical predictors of a normal stress only PET-MPI included lower age, the absence of CAD, and female gender, but not body mass index. Blinded reads of 50 additional consecutive PET-MPI from patients with selected clinical predictors (age <65 years, no known CAD) were then performed. Of these, 40 (80%) were normal by previous rest-stress reading, and 34 (68%) were categorized as not requiring additional images after stress only reading. PET stress only imaging would have resulted in a mean reduction of radiation exposure of 2.4 mSv per study according to a published radiation estimate. Conclusion: Stress only Rb82 PET-MPI is a feasible strategy to reduce resource utilization and radiation exposure associated with MPI. This strategy would be most applicable to patients with a lower pretest likelihood. [ABSTRACT FROM AUTHOR]

Abstract: The habitable zone (HZ) is conventionally the thin shell of space around a star within which liquid water is thermally stable on the surface of an Earth-like planet (Kasting et al., 1993). However, life on Earth is not restricted to the surface and includes a “deep biosphere” reaching several km in depth. Similarly, subsurface liquid water maintained by internal planetary heat could potentially support life well outside conventional HZs. We introduce a new term, subsurface-habitability zone (SSHZ) to denote the range of distances from a star within which rocky planets are habitable at any depth below their surfaces up to a stipulated maximum, and show how SSHZs can be estimated from a model relating temperature, depth and orbital distance. We present results for Earth-like, Mars-like and selected extrasolar terrestrial planets, and conclude that SSHZs are several times wider and include many more planets than conventional surface-based habitable zones. [Copyright &y& Elsevier]

Abstract: Buildings represent long-term, capital-intensive investments designed to perform for decades into the future. Consequently, the potential for changes in climate across the design lifetime of built environments represents an immediate challenge for planning, design, and construction. In this study, we consider the opportunities to assess Climate Sensitivity and adaptive opportunities associated with green building practice. We developed a pair of complementary indicators called the Climate Sensitivity Index (CSI) and Climate Adaptation Opportunity Index (CAOI). These indicators are applied to evaluate individual strategies (“credits”) within the Leadership in Energy and Environmental Design (LEED™) for New Construction rating system. The indices provide two complementary scores for each strategy. The CSI reflects potential sensitivity to changing conditions (i.e., risks to performance outcomes), and the CAOI indicates potential adaptive opportunities (i.e., plausible strategies to adapt to changing conditions). We apply the indices to retrospectively examine the prevalence of potentially sensitive and adaptive practices among a global set of 2440 LEED-certified projects. Adaptive opportunities were more prevalent than sensitivities in the LEED-NC rating system. The CSI and CAOI indices illustrate how information can be derived by interpreting patterns of LEED credit achievement. The indices will be available within a suite of analytical tools in the Green Building Information Gateway (www.gbig.org). [Copyright &y& Elsevier]

Understanding how species and ecosystems respond to climate change has become a major focus of ecology and conservation biology. Modelling approaches provide important tools for making future projections, but current models of the climate-biosphere interface remain overly simplistic, undermining the credibility of projections. We identify five ways in which substantial advances could be made in the next few years: (i) improving the accessibility and efficiency of biodiversity monitoring data, (ii) quantifying the main determinants of the sensitivity of species to climate change, (iii) incorporating community dynamics into projections of biodiversity responses, (iv) accounting for the influence of evolutionary processes on the response of species to climate change, and (v) improving the biophysical rule sets that define functional groupings of species in global models. [Copyright &y& Elsevier]

Subsurface storage of hydrogen, e.g. in depleted oil and gas fields (DOGF), is suggested as a means to overcome imbalances between supply and demand in the renewable energy sector. However, hydrogen is an electron donor for subsurface microbial processes, which may have important implications for hydrogen recovery, gas injectivity and corrosion. Here, we review the controls on the three major hydrogen consuming processes in the subsurface, methanogenesis, homoacetogenesis, and sulfate reduction, as a basis to estimate the risk for microbial growth in geological hydrogen storage. Evaluating our data on 42 DOGF showed that five of the fields may be considered sterile with respect to hydrogen-consuming microorganisms due to temperatures >122 °C. Only six DOGF can sustain all of the hydrogen consuming processes, due to either temperature, salinity or pressure constraints in the remaining fields. We calculated a potential microbial growth in the order of 1–17*107 cells ml−1 for DOGF with favorable conditions for microbial growth, reached after 0.1–19 days for growing cells and 0.2–6.6 years for resting cells. The associated hydrogen consumption is negligible to small (<0.01–3.2% of the stored hydrogen). Our results can help inform decisions about where hydrogen will be stored in the future. [Display omitted] • Review of the most important hydrogen-oxidizing microorganisms in the underground. • Elucidation of the growth criteria for 518 strains of the major hydrogen-oxidizers. • Screening of 42 depleted oil and gas fields (DOGF) for possible microbial growth. • Calculation of the microbial growth and hydrogen consumption in DOGF. [ABSTRACT FROM AUTHOR]

Background: Although prior national reports have identified trends in the underutilization of transcatheter aortic valve replacement (TAVR) in Afro-American and Latino populations, racial and ethnic healthcare disparities in TAVR use in the State of Connecticut have not been previously reported.Methods: We conducted a retrospective analysis of 1461 patients undergoing TAVR at our institute between from 2012 to 2020. Baseline demographics, procedural characteristics, clinical outcomes, median incomes and insurance coverage were compared between 1417 Caucasian and 44 minority patients, including 23 patients designated as Afro-American and 10 designated as Latino. Demographics of TAVR utilization at our institution were further compared to 6 additional Connecticut TAVR centers using Connecticut Hospital Association (CHA) ChimeData detailing hospital discharges for DRG 266 and 267.Results: In comparison to Caucasian patients, minority cohorts were younger (75.7 ± 9.0 vs 81.5 ± 5.1 years, p < 0.001) and had more co-morbidities including diabetes (64% vs 34%, p < 001), coronary artery disease (95% vs 78%, p = 0.039), end stage renal disease requiring dialysis (9% vs 3%, p = 0.009) and atrial fibrillation (77% vs 62%, p = 0.041). The two groups did not differ with respect to other risk factors or co-morbidities, baseline echocardiographic or CTA findings, STS risk score, or procedural technique. Minority patients had a longer length of hospital stay (9.5 ± 9.0 vs 6.4 ± 6.9 days, p = 0.003), but did not differ with respect to procedural complications. Socioeconomic differences between the two groups included lower median incomes and higher rates of Medicaid or no insurance coverage for minority versus Caucasian patients. CHA ChimeData revealed a similar underutilization of TAVR in minority subgroups in the remaining 6 Connecticut TAVR centers.Conclusions: Despite statewide demographics describing 10.7% and 15.7% of the total population as Afro-American and Latino, respectively, only 3.0% of the total TAVR procedures performed at a large Connecticut health care facility were performed in minority subgroups. Despite having a higher burden of co-morbidities, minority patients had similar outcomes compared to Caucasian patients. Similar racial and ethnic disparities in TAVR utilization were confirmed statewide using CHA ChimeData. [ABSTRACT FROM AUTHOR]

Almost one-third of globally known tree species are threatened with extinction, calling for a better understanding of the vulnerability of tree species to different threats. Quantifying changes in vital rates (e.g., survival, growth, or reproduction) in response to threats has helped assess which of these rates of a given species are the most critical to the population response to a threat. To more generally understand which types of tree species, based on their life-history strategies, are more vulnerable compared with others, comparative analyses of demographic data across the phylogenetic 'Tree of trees' and biomes are needed. Demographic model parameterization for comparative analyses hinges on improving coverage of data on mortality and recruitment (e.g., through distributed observation networks). Systematic modeling would greatly help explore which life-history strategies of species are the best predictors of their vulnerability to different threats, prioritize data collection, and potentially suggest management alternatives. Conserving the tree species of the world requires syntheses on which tree species are most vulnerable to pressing threats, such as climate change, invasive pests and pathogens, or selective logging. Here, we review the population and forest dynamics models that, when parameterized with data from population studies, forest inventories, or tree rings, have been used for identifying life-history strategies of species and threat-related changes in population demography and dynamics. The available evidence suggests that slow-growing and/or long-lived species are the most vulnerable. However, a lack of comparative, multi-species studies still challenges more precise predictions of the vulnerability of tree species to threats. Improving data coverage for mortality and recruitment, and accounting for interactions among threats, would greatly advance vulnerability assessments for conservation prioritizations of trees worldwide. [ABSTRACT FROM AUTHOR]

Increased bleeding risks have been documented in patients exposed to P2Y 12 inhibitors within 5 days of coronary artery bypass surgery (CABG). This study aimed to determine the relative CABG bleeding risks of clopidogrel versus ticagrelor exposure and the proper time course of ticagrelor discontinuation prior to surgery. Clinical outcomes were assessed in 2075 isolated CABG patients, including 375 who had received P2Y 12 inhibitors within 5 days of surgery (155 clopidogrel, 213 ticagrelor, 7 prasugrel). BARC-4 CABG bleeding complications and perioperative blood product usage were assessed in propensity-matched P2Y 12 -inhibited and non-P2Y 12 -inhibited cohorts. P2Y 12 -inhibited patients (n = 375) in comparison to matched non-P2Y 12 -inhibited patients (n = 1138) had higher rates of re-operation for bleeding (3.8 % vs 1.3 %, p = 0.003), postoperative red blood cell transfusion ≥5 units (5.7 % vs 2.7 %, p = 0.007), and intraoperative and postoperative blood product utilization (42.3 % vs 27.1 %, p < 0.001; 41.8 % vs 32.2 %, p < 0.001, respectively). Univariate predictors of BARC-4 bleeding included clopidogrel (OR: 2.145, 95 % CI: 1.131–4.067, p = 0.019) and ticagrelor discontinued within 3 days of surgery (OR: 2.153, 95 % CI: 1.003–4.169, p = 0.049). Multivariate logistic regression demonstrated that only clopidogrel exposure was an independent BARC-4 bleeding predictor (OR: 1.850, 95 % CI: 1.007–3.398, p = 0.048). Unadjusted ticagrelor patients with drug discontinuation 4–5 days prior to CABG only demonstrated higher rates of perioperative platelet transfusion, without additional signs of excessive bleeding. Clopidogrel exposure within 5 days of CABG is an independent predictor of BARC-4 bleeding, whereas major ticagrelor bleeding effects are confined to drug exposure within 3 days of surgery. • Perioperative bleeding complications were assessed in 2,075 patients undergoing isolated CABG. • The study group included 375 patients that had received P2Y 12 inhibitor therapy within 5 days of surgery. • Propensity-matched P2Y 12 -inhibited patients had increased BARC-4 bleeding and perioperative blood product utilization. • Clopidogrel exposure within 5 days of CABG was an independent predictor of BARC-4 bleeding. • Major ticagrelor bleeding effects were confined to drug exposure within 3 days of surgery. [ABSTRACT FROM AUTHOR]

Understanding and forecasting species’ geographic distributions in the face of global change is a central priority in biodiversity science. The existing view is that one must choose between correlative models for many species versus process-based models for few species. We suggest that opportunities exist to produce process-based range models for many species, by using hierarchical and inverse modeling to borrow strength across species, fill data gaps, fuse diverse data sets, and model across biological and spatial scales. We review the statistical ecology and population and range modeling literature, illustrating these modeling strategies in action. A variety of large, coordinated ecological datasets that can feed into these modeling solutions already exist, and we highlight organisms that seem ripe for the challenge. [ABSTRACT FROM AUTHOR]

Rigorous monitoring of Earth's terrestrial surface requires mapping estimates of land cover and of their errors in space and time. Estimation of error in land-cover change detection currently relies heavily on external, post hoc validation—i.e., comparison of estimated cover to independent values that are assumed to be true. However, reference data are themselves uncertain, and acquiring observations coincident with historical data is often impossible. Complementarily, modeling the transmission, or propagation, of error through the processes of classification and change detection provides an internal means to estimate classification and change-detection error at the scale of pixels. Modeling uncertainty around the estimate of fractional, “continuous-field” cover as a standard Normal distribution in each pixel at each of two times, we derive a method for propagating this uncertainty to categorical land cover-classification and change detection. We demonstrate the approach for mapping forest-cover change and its uncertainty based on bi-temporal estimates of percent-tree cover and their associated root-mean-square errors (RMSE). The method described here propagates only the imprecision component of error and not bias, so neither the resulting categorical estimates of cover nor the detection of change (e.g., forest loss) are affected by the transmission of uncertainty. However, propagating the RMSE of input estimates into probabilities of forest cover and change enables mapping and visualization of the spatial distribution of the imprecision resulting from model-based estimation of tree cover and from selection of the threshold of tree cover to define “forest”. When compared to reference data with a fixed definition of forest (e.g., ≥ 30% tree cover) the threshold effect is an importance source of apparent error in forest-cover and -change estimates. The approach described here provides a useful description of classification and change-detection certainty and can accommodate any definition of forest based on tree cover—an especially important consideration given the variety of institutional definitions of forest cover based on remotely sensible structural characteristics. [ABSTRACT FROM AUTHOR]

Poly- l -lactide (PLLA) is a popular choice for medical devices due to its bioresorbability and superior mechanical properties compared with other polymers. However, although PLLA has been investigated for use in bioresorbable cardiovascular stents, it presents application-specific limitations which hamper device therapies. These include low toughness and strength compared with metals used for this purpose, and slow degradation. Blending PLLA with novel polyethylene glycol functionalised poly(l -lactide-co- ε -caprolactone) (PLCL-PEG) materials has been investigated here to tailor the mechanical properties and degradation behaviour of PLLA. This exciting approach provides a foundation for a next generation of bioresorbable materials whose properties can be rapidly tuned. The degradation of PLLA was significantly accelerated by addition of PLCL-PEG. After 30 days of degradation, several structural changes were observed in the polymer blends, which were dependent on the level of PLCL-PEG addition. Blends with low PLCL-PEG content displayed enthalpy relaxation, resulting in embrittlement, while blends with high PLCL-PEG content displayed crystallisation, due to enhanced chain mobility brought on by chain scission, also causing embrittlement. Moderate PLCL-PEG additions (10% PLCL(70:30)-PEG and 20–30% PLCL(80:20)-PEG) stabilised the structure, reducing the extent of enthalpy relaxation and crystallisation and thus retaining ductility. Compositional optimisation identified a sweet spot for this blend strategy, whereby the ductility was enhanced while maintaining strength. Our results indicate that blending PLLA with PLCL-PEG provides an effective method of tuning the degradation timescale and mechanical properties of PLLA, and provides important new insight into the mechanisms of structural relaxations that occur during degradation, and strategies for regulating these. [ABSTRACT FROM AUTHOR]