3,500 research outputs found

    Linking inter-annual variation in environment, phenology, and abundance for a montane butterfly community (article)

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    This is the final version. Available from the Ecological Society of America via the DOI in this record. The dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.1963Climate change has caused widespread shifts in species’ phenology, but the consequences for population and community dynamics remain unclear because of uncertainty regarding the species-specific drivers of phenology and abundance, and the implications for synchrony among interacting species. Here, we develop a statistical model to quantify inter-annual variation in phenology and abundance over an environmental gradient, and use it to identify potential drivers of phenology and abundance in co-occurring species. We fit the model to counts of 10 butterfly species with single annual generations over a mountain elevation gradient, as an exemplar system in which temporally limited availability of biotic resources and favorable abiotic conditions impose narrow windows of seasonal activity. We estimate parameters describing changes in abundance, and the peak time and duration of the flight period, over ten years (2004–2013) and across twenty sample locations (930–2,050 m) in central Spain. We also use the model outputs to investigate relationships of phenology and abundance with temperature and rainfall. Annual shifts in phenology were remarkably consistent among species, typically showing earlier flight periods during years with warm conditions in March or May–June. In contrast, inter-annual variation in relative abundance was more variable among species, and generally less well associated with climatic conditions. Nevertheless, warmer temperatures in June were associated with increased relative population growth in three species, and five species had increased relative population growth in years with earlier flight periods. These results suggest that broadly coherent interspecific changes to phenology could help to maintain temporal synchrony in community dynamics under climate change, but that the relative composition of communities may vary due to interspecific inconsistency in population dynamic responses to climate change. However, it may still be possible to predict abundance change for species based on a robust understanding of relationships between their population dynamics and phenology, and the environmental drivers of both.Royal SocietyNatural Environment Research Counci

    Thermodynamic analysis of the Quantum Critical behavior of Ce-lattice compounds

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    A systematic analysis of low temperature magnetic phase diagrams of Ce compounds is performed in order to recognize the thermodynamic conditions to be fulfilled by those systems to reach a quantum critical regime and, alternatively, to identify other kinds of low temperature behaviors. Based on specific heat (CmC_m) and entropy (SmS_m) results, three different types of phase diagrams are recognized: i) with the entropy involved into the ordered phase (SMOS_{MO}) decreasing proportionally to the ordering temperature (TMOT_{MO}), ii) those showing a transference of degrees of freedom from the ordered phase to a non-magnetic component, with their Cm(TMO)C_m(T_{MO}) jump (ΔCm\Delta C_m) vanishing at finite temperature, and iii) those ending in a critical point at finite temperature because their ΔCm\Delta C_m do not decrease with TMOT_{MO} producing an entropy accumulation at low temperature. Only those systems belonging to the first case, i.e. with SMO0S_{MO}\to 0 as TMO0T_{MO}\to 0, can be regarded as candidates for quantum critical behavior. Their magnetic phase boundaries deviate from the classical negative curvature below T2.5T\approx 2.5\,K, denouncing frequent misleading extrapolations down to T=0. Different characteristic concentrations are recognized and analyzed for Ce-ligand alloyed systems. Particularly, a pre-critical region is identified, where the nature of the magnetic transition undergoes significant modifications, with its Cm/T\partial C_m/\partial T discontinuity strongly affected by magnetic field and showing an increasing remnant entropy at T0T\to 0. Physical constraints arising from the third law at T0T\to 0 are discussed and recognized from experimental results

    Methylenetetrahydrofolate reductase polymorphism 677C>T is associated with peripheral arterial disease in type 2 diabetes

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    BACKGROUND: Individuals with diabetes are twice as likely to develop peripheral arterial disease (PAD), the manifestation of extensive atherosclerosis throughout the lower extremities. One putative determinant of PAD is the 677C>T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR), which has previously been found to associate with various diabetic complications including retinopathy, nephropathy, atherosclerosis and coronary heart disease. The objective of this study was to investigate a possible role for the MTHFR 677C>T gene polymorphism with PAD in subjects with type 2 diabetes from an isolated aboriginal Canadian population. METHODS: The 677C>T MTHFR gene polymorphism was genotyped in 138 subjects of Oji-Cree descent. Participants were selected from a community-wide survey that included PAD assessment by ankle-brachial index (ABI) measurement, and also intermittent claudication assessment by the Rose questionnaire. RESULTS: MTHFR 677T allele carriers had an increased risk of PAD with an odds ratio of 3.54 (95% CI 1.01, 12.4), P = 0.049, after adjustment for age, sex, duration of diabetes, hypertension, current smoking habits, and use of insulin or oral treatment for diabetes. None of these additional co-variables was significantly associated with PAD. No association was found between MTHFR genotype and intermittent claudication. CONCLUSION: The genetic influence of the MTHFR 677C>T genotype on diabetic PAD is modest, yet for the Oji-Cree it is a major risk factor in comparison to other traditional risk factors

    Degradation of ribosomal and chaperone proteins is attenuated during the differentiation of replicatively aged C2C12 myoblasts

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    Background: Cell assays are important for investigating the mechanisms of ageing, including losses in protein homeostasis and ‘proteostasis collapse’. We used novel isotopic labelling and proteomic methods to investigate protein turnover in replicatively aged (>140 population doublings) murine C2C12 myoblasts that exhibit impaired differentiation and serve as a model for age-related declines in muscle homeostasis. Methods: The Absolute Dynamic Profiling Technique for Proteo-mics (Proteo-ADPT) was used to investigate proteostasis in young (passage 6-10) and replicatively aged (passage 48-50) C2C12 myoblast cultures supplemented with deuterium oxide (D2O) during early (0 h – 24 h) or late (72 h – 96 h) periods of differentiation. Peptide mass spectrometry was used to quantify the absolute rates of abundance change, synthesis and degradation of individual proteins. Results: Young cells exhibited a consistent ~25% rise in protein accretion over the 96-h experimental period. In aged cells, protein accretion increased by 32% (P<0.05) during early differentiation, but then fell back to baseline levels by 96-h. Proteo-ADPT encompassed 116 proteins and 74 proteins exhibited significantly (P<0.05, FDR <5% interaction between age * differentiation stage) different changes in abundance between young and aged cells at early and later periods of differentiation, including proteins associated with translation, glycolysis, cell-cell adhesion, ribosomal biogenesis and the regulation of cell shape. During early differentiation, heat shock and ribosomal protein abundances increased in aged cells due to suppressed degradation rather than heightened synthesis. For instance, HS90A increased at a rate of 10.62 ± 1.60 ng/well/h in aged which was significantly greater than the rate of accretion (1.86 ± 0.49 ng/well/h) in young cells. HS90A synthesis was similar in young (21.23 ± 3.40 ng/well/h) and aged (23.69 ± 1.13 ng/well/h) but HS90A degradation was significantly (P = 0.05) greater in young (19.37 ± 2.93 ng/well/h) versus aged (13.06 ± 0.76 ng/well/h) cells. During later differentiation the HS90A degradation (8.94 ± 0.38 ng/well/h) and synthesis (7.89 ± 1.28 ng/well/h) declined and were significantly less than the positive net balance between synthesis and degradation (ASR = 28.14 ± 3.70 ng/well/h vs ADR = 21.49 ± 3.13 ng/well/h) in young cells. Conclusion: Our results suggest a loss of proteome quality as a precursor to the lack of fusion of aged myoblasts. The quality of key chaperone proteins, including HS90A, HS90B and HSP7C was reduced in aged cells and may account for the disruption to cell signalling required for the later stages of differentiation and fusion

    ‘Should a mammographic screening programme carry the warning: Screening can damage your health!’?

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    The balanced presentation afforded by convening a Citizens' Jury when considering a major question such as the introduction of a breast screening programme is advocated. This method would enable account to be taken of all the costs, both human and financial, to all those affected, both participating and organizing, as well as the benefits. Provision of such a democratic opportunity enables consideration to be given to a broad range of factors, by selection of an appropriate range of witnesses, with the advantage of involving the lay public in this decision-making process. Attendance by health correspondents, medical journalists and other media representatives enables publicization of a democracy in action whilst helping to inform the wider debate. Such an exercise could inform whether the NHS BSP should continue in its current form. © 1999 Cancer Research Campaig

    Dynamic Profiling of Protein Mole Synthesis Rates During C2C12 Myoblast Differentiation

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    Mole (MSR) and fractional (FSR) synthesis rates of proteins during C2C12 myoblast differentiation were investigated. Myoblast cultures supplemented with D2O during 0–24 h or 72–96 h of differentiation were analysed by LC‐MS/MS to calculate protein FSR and MSR after samples were spiked with yeast alcohol dehydrogenase (ADH1). Profiling of 153 proteins detected 70 significant (p ≤ 0.05, FDR ≤1 %) differences in abundance between cell states. Early differentiation was enriched by clusters of ribosomal and heat shock proteins, whereas later differentiation was associated with actin filament binding. The median (first ‐ third quartile) FSR (%/h) during early differentiation 4.1 (2.7‐5.3) was ∼2‐fold greater than later differentiation 1.7 (1.0‐2.2), equating to MSR of 0.64, (0.38‐1.2) and 0.28, (0.1‐0.5) fmol/h/ug total protein, respectively. MSR corresponded more closely with abundance data and highlighted proteins associated with glycolytic processes and intermediate filament protein binding that were not evident amongst FSR data. Similarly, MSR during early differentiation accounted for 78 % of the variation in protein abundance during later differentiation, whereas FSR accounted for 4%. Conclusively, the interpretation of protein synthesis data differed when reported in mole or fractional terms, which has consequences when studying the allocation of cellular resources

    Identification of novel subgroup a variants with enhanced receptor binding and replicative capacity in primary isolates of anaemogenic strains of feline leukaemia virus

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    &lt;b&gt;BACKGROUND:&lt;/b&gt; The development of anaemia in feline leukaemia virus (FeLV)-infected cats is associated with the emergence of a novel viral subgroup, FeLV-C. FeLV-C arises from the subgroup that is transmitted, FeLV-A, through alterations in the amino acid sequence of the receptor binding domain (RBD) of the envelope glycoprotein that result in a shift in the receptor usage and the cell tropism of the virus. The factors that influence the transition from subgroup A to subgroup C remain unclear, one possibility is that a selective pressure in the host drives the acquisition of mutations in the RBD, creating A/C intermediates with enhanced abilities to interact with the FeLV-C receptor, FLVCR. In order to understand further the emergence of FeLV-C in the infected cat, we examined primary isolates of FeLV-C for evidence of FeLV-A variants that bore mutations consistent with a gradual evolution from FeLV-A to FeLV-C.&lt;p&gt;&lt;/p&gt; &lt;b&gt;RESULTS:&lt;/b&gt; Within each isolate of FeLV-C, we identified variants that were ostensibly subgroup A by nucleic acid sequence comparisons, but which bore mutations in the RBD. One such mutation, N91D, was present in multiple isolates and when engineered into a molecular clone of the prototypic FeLV-A (Glasgow-1), enhanced replication was noted in feline cells. Expression of the N91D Env on murine leukaemia virus (MLV) pseudotypes enhanced viral entry mediated by the FeLV-A receptor THTR1 while soluble FeLV-A Env bearing the N91D mutation bound more efficiently to mouse or guinea pig cells bearing the FeLV-A and -C receptors. Long-term in vitro culture of variants bearing the N91D substitution in the presence of anti-FeLV gp70 antibodies did not result in the emergence of FeLV-C variants, suggesting that additional selective pressures in the infected cat may drive the subsequent evolution from subgroup A to subgroup C.&lt;p&gt;&lt;/p&gt; &lt;b&gt;CONCLUSIONS:&lt;/b&gt; Our data support a model in which variants of FeLV-A, bearing subtle differences in the RBD of Env, may be predisposed towards enhanced replication in vivo and subsequent conversion to FeLV-C. The selection pressures in vivo that drive the emergence of FeLV-C in a proportion of infected cats remain to be established

    Rationale, design and conduct of a randomised controlled trial evaluating a primary care-based complex intervention to improve the quality of life of heart failure patients: HICMan (Heidelberg Integrated Case Management) : study protocol

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    Background: Chronic congestive heart failure (CHF) is a complex disease with rising prevalence, compromised quality of life (QoL), unplanned hospital admissions, high mortality and therefore high burden of illness. The delivery of care for these patients has been criticized and new strategies addressing crucial domains of care have been shown to be effective on patients' health outcomes, although these trials were conducted in secondary care or in highly organised Health Maintenance Organisations. It remains unclear whether a comprehensive primary care-based case management for the treating general practitioner (GP) can improve patients' QoL. Methods/Design: HICMan is a randomised controlled trial with patients as the unit of randomisation. Aim is to evaluate a structured, standardized and comprehensive complex intervention for patients with CHF in a 12-months follow-up trial. Patients from intervention group receive specific patient leaflets and documentation booklets as well as regular monitoring and screening by a prior trained practice nurse, who gives feedback to the GP upon urgency. Monitoring and screening address aspects of disease-specific selfmanagement, (non)pharmacological adherence and psychosomatic and geriatric comorbidity. GPs are invited to provide a tailored structured counselling 4 times during the trial and receive an additional feedback on pharmacotherapy relevant to prognosis (data of baseline documentation). Patients from control group receive usual care by their GPs, who were introduced to guidelineoriented management and a tailored health counselling concept. Main outcome measurement for patients' QoL is the scale physical functioning of the SF-36 health questionnaire in a 12-month follow-up. Secondary outcomes are the disease specific QoL measured by the Kansas City Cardiomyopathy questionnaire (KCCQ), depression and anxiety disorders (PHQ-9, GAD-7), adherence (EHFScBS and SANA), quality of care measured by an adapted version of the Patient Chronic Illness Assessment of Care questionnaire (PACIC) and NTproBNP. In addition, comprehensive clinical data are collected about health status, comorbidity, medication and health care utilisation. Discussion: As the targeted patient group is mostly cared for and treated by GPs, a comprehensive primary care-based guideline implementation including somatic, psychosomatic and organisational aspects of the delivery of care (HICMAn) is a promising intervention applying proven strategies for optimal care. Trial registration: Current Controlled Trials ISRCTN30822978

    Anti–Vascular Endothelial Growth Factor Drugs Compared With Panretinal Photocoagulation for the Treatment of Proliferative Diabetic Retinopathy: A Cost-Effectiveness Analysis

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    \ua9 2024Objectives: This study aimed to evaluate the cost-effectiveness of anti–vascular endothelial growth factor drugs (anti-VEGFs) compared with panretinal photocoagulation (PRP) for treating proliferative diabetic retinopathy (PDR) in the United Kingdom. Methods: A discrete event simulation model was developed, informed by individual participant data meta-analysis. The model captures treatment effects on best corrected visual acuity in both eyes, and the occurrence of diabetic macular edema and vitreous hemorrhage. The model also estimates the value of undertaking further research to resolve decision uncertainty. Results: Anti-VEGFs are unlikely to generate clinically meaningful benefits over PRP. The model predicted anti-VEGFs be more costly and similarly effective as PRP, generating 0.029 fewer quality-adjusted life-years at an additional cost of \ua33688, with a net health benefit of −0.214 at a \ua320 000 willingness-to-pay threshold. Scenario analysis results suggest that only under very select conditions may anti-VEGFs offer potential for cost-effective treatment of PDR. The consequences of loss to follow-up were an important driver of model outcomes. Conclusions: Anti-VEGFs are unlikely to be a cost-effective treatment for early PDR compared with PRP. Anti-VEGFs are generally associated with higher costs and similar health outcomes across various scenarios. Although anti-VEGFs were associated with lower diabetic macular edema rates, the number of cases avoided is insufficient to offset the additional treatment costs. Key uncertainties relate to the long-term comparative effectiveness of anti-VEGFs, particularly considering the real-world rates and consequences of treatment nonadherence. Further research on long-term visual acuity and rates of vision-threatening complications may be beneficial in resolving uncertainties

    The trade-off between taxi time and fuel consumption in airport ground movement

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    Environmental impact is a very important agenda item in many sectors nowadays, which the air transportation sector is also trying to reduce as much as possible. One area which has remained relatively unexplored in this context is the ground movement problem for aircraft on the airport’s surface. Aircraft have to be routed from a gate to a runway and vice versa and it is still unknown whether fuel burn and environmental impact reductions will best result from purely minimising the taxi times or whether it is also important to avoid multiple acceleration phases. This paper presents a newly developed multi-objective approach for analysing the trade-off between taxi time and fuel consumption during taxiing. The approach consists of a combination of a graph-based routing algorithm and a population adaptive immune algorithm to discover different speed profiles of aircraft. Analysis with data from a European hub airport has highlighted the impressive performance of the new approach. Furthermore, it is shown that the trade-off between taxi time and fuel consumption is very sensitive to the fuel-related objective function which is used
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