1,171 research outputs found

    Evaluating Process-Based Integrated Assessment Models of Climate Change Mitigation

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    Process-based integrated assessment models (IAMs) analyse transformation pathways to mitigate climate change. Confidence in models is established by testing their structural assumptions and comparing their behaviour against observations as well as other models. Climate model evaluation is concerted, and prominently reported in a dedicated chapter in the IPCC WG1 assessments. By comparison, evaluation of process-based IAMs tends to be less visible and more dispersed among modelling teams, with the exception of model inter-comparison projects. We contribute the first comprehensive analysis of process-based IAM evaluation, drawing on a wide range of examples across eight different evaluation methods testing both structural and behavioural validity. For each evaluation method, we compare its application to process-based IAMs with its application to climate models, noting similarities and differences, and seeking useful insights for strengthening the evaluation of process-based IAMs. We find that each evaluation method has distinctive strengths and limitations, as well as constraints on their application. We develop a systematic evaluation framework combining multiple methods that should be embedded within the development and use of process-based IAMs

    New Structural Insights into the Genome and Minor Capsid Proteins of BK Polyomavirus using Cryo-Electron Microscopy

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    BK polyomavirus is the causative agent of several diseases in transplant patients and the immunosuppressed. In order to better understand the structure and life cycle of BK, we produced infectious virions and VP1-only virus-like particles in cell culture, and determined their three-dimensional structures using cryo-electron microscopy (EM) and single-particle image processing. The resulting 7.6-Å resolution structure of BK and 9.1-Å resolution of the virus-like particles are the highest-resolution cryo-EM structures of any polyomavirus. These structures confirm that the architecture of the major structural protein components of these human polyomaviruses are similar to previous structures from other hosts, but give new insight into the location and role of the enigmatic minor structural proteins, VP2 and VP3. We also observe two shells of electron density, which we attribute to a structurally ordered part of the viral genome, and discrete contacts between this density and both VP1 and the minor capsid proteins

    Morphological evolution of creek networks in 10 restored coastal wetlands in the UK

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    Coastal wetlands provide crucial ecosystem services including flood protection and carbon storage, but are being lost rapidly worldwide to the combined effects of sea-level rise, erosion and coastal urbanisation. Managed Realignment (MR) aims to mitigate for these losses by restoring reclaimed land to tidal influence. Data of creek evolution is critical to assess the performance of design strategies and improve design and implementation practices. This data descriptor provides a dataset of the horizontal morphological evolution of creek systems from various initial conditions in 10 MR schemes across the UK. Using a semi-automated workflow, morphological creek parameters were extracted from 52 lidar datasets at 1 m horizontal resolution spanning 2 to 20 years post-breach. This constitutes the most comprehensive systematic monitoring of MR creek morphology to date. The dataset will assist future MR design and provide baseline morphological information for ecological and biogeochemical surveying

    Differential iron requirements for osteoblast and adipocyte differentiation

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    Bone marrow mesenchymal progenitor cells are precursors for various cell types including osteoblasts, adipocytes, and chondrocytes. The external environment and signals act to direct the pathway of differentiation. Importantly, situations such as aging and chronic kidney disease display alterations in the balance of osteoblast and adipocyte differentiation, adversely affecting bone integrity. Iron deficiency, which can often occur during aging and chronic kidney disease, is associated with reduced bone density. The purpose of this study was to assess the effects of iron deficiency on the capacity of progenitor cell differentiation pathways. Mouse and human progenitor cells, differentiated under standard osteoblast and adipocyte protocols in the presence of the iron chelator deferoxamine (DFO), were used. Under osteogenic conditions, 5μM DFO significantly impaired expression of critical osteoblast genes, including osteocalcin, type 1 collagen, and dentin matrix protein 1. This led to a reduction in alkaline phosphatase activity and impaired mineralization. Despite prolonged exposure to chronic iron deficiency, cells retained viability as well as normal hypoxic responses with significant increases in transferrin receptor and protein accumulation of hypoxia inducible factor 1α. Similar concentrations of DFO were used when cells were maintained in adipogenic conditions. In contrast to osteoblast differentiation, DFO modestly suppressed adipocyte gene expression of peroxisome-proliferating activated receptor gamma, lipoprotein lipase, and adiponectin at earlier time points with normalization at later stages. Lipid accumulation was also similar in all conditions. These data suggest the critical importance of iron in osteoblast differentiation, and as long as the external stimuli are present, iron deficiency does not impede adipogenesis. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.Daniel F. Edwards III, Christopher J. Miller, Arelis Quintana-Martinez, Christian S. Wright, Matthew Prideaux, Gerald J. Atkins, William R. Thompson, and Erica L. Clinkenbear

    Effects of rapid prey evolution on predator-prey cycles

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    We study the qualitative properties of population cycles in a predator-prey system where genetic variability allows contemporary rapid evolution of the prey. Previous numerical studies have found that prey evolution in response to changing predation risk can have major quantitative and qualitative effects on predator-prey cycles, including: (i) large increases in cycle period, (ii) changes in phase relations (so that predator and prey are cycling exactly out of phase, rather than the classical quarter-period phase lag), and (iii) "cryptic" cycles in which total prey density remains nearly constant while predator density and prey traits cycle. Here we focus on a chemostat model motivated by our experimental system [Fussmann et al. 2000,Yoshida et al. 2003] with algae (prey) and rotifers (predators), in which the prey exhibit rapid evolution in their level of defense against predation. We show that the effects of rapid prey evolution are robust and general, and furthermore that they occur in a specific but biologically relevant region of parameter space: when traits that greatly reduce predation risk are relatively cheap (in terms of reductions in other fitness components), when there is coexistence between the two prey types and the predator, and when the interaction between predators and undefended prey alone would produce cycles. Because defense has been shown to be inexpensive, even cost-free, in a number of systems [Andersson and Levin 1999, Gagneux et al. 2006,Yoshida et al. 2004], our discoveries may well be reproduced in other model systems, and in nature. Finally, some of our key results are extended to a general model in which functional forms for the predation rate and prey birth rate are not specified.Comment: 35 pages, 8 figure

    Making things happen : a model of proactive motivation

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    Being proactive is about making things happen, anticipating and preventing problems, and seizing opportunities. It involves self-initiated efforts to bring about change in the work environment and/or oneself to achieve a different future. The authors develop existing perspectives on this topic by identifying proactivity as a goal-driven process involving both the setting of a proactive goal (proactive goal generation) and striving to achieve that proactive goal (proactive goal striving). The authors identify a range of proactive goals that individuals can pursue in organizations. These vary on two dimensions: the future they aim to bring about (achieving a better personal fit within one’s work environment, improving the organization’s internal functioning, or enhancing the organization’s strategic fit with its environment) and whether the self or situation is being changed. The authors then identify “can do,” “reason to,” and “energized to” motivational states that prompt proactive goal generation and sustain goal striving. Can do motivation arises from perceptions of self-efficacy, control, and (low) cost. Reason to motivation relates to why someone is proactive, including reasons flowing from intrinsic, integrated, and identified motivation. Energized to motivation refers to activated positive affective states that prompt proactive goal processes. The authors suggest more distal antecedents, including individual differences (e.g., personality, values, knowledge and ability) as well as contextual variations in leadership, work design, and interpersonal climate, that influence the proactive motivational states and thereby boost or inhibit proactive goal processes. Finally, the authors summarize priorities for future researc

    Course and predictors of eating disorder symptoms, anxiety symptoms, and pandemic-related eating disorder concerns among adults with eating disorders during the first year of the COVID-19 pandemic

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    Objective: The COVID-19 pandemic and public health mitigation measures have negatively impacted individuals with eating disorders (ED). We evaluated changes in and predictors of ED symptoms, pandemic-related ED concerns, and anxiety symptoms across the first 12 months of the COVID-19 pandemic among individuals with self-reported EDs in the United States (US), Sweden (SE), and the Netherlands (NL). Method: Participants in the US (N = 510), SE (N = 982), and NL (N = 510) completed an online survey assessing ED symptoms (binge eating, restriction, compensatory behaviors, and anxiety about being unable to exercise), general anxiety symptoms, and pandemic-related ED concerns about accessing food, lack of structure and social support, being in a triggering environment, and food and treatment costs. In the US and NL, respondents completed surveys beginning April 2020 and continuing monthly for a year. In SE, respondents completed baseline surveys in May 2020, a six-month follow-up around December 2020, and a 12-month follow-up in May 2021. Results: Three patterns emerged: (1) a curvilinear course with the highest level of symptoms at baseline, declining through November 2020, and increasing through the rest of the year; (2) a linear declining course over time; and (3) a stable course with no changes. Worries about COVID-19 infection, lockdown, concerns about lack of structure and social support, and concerns about accessing food consistent with one's recovery meal plan predicted increases in ED symptoms. Discussion: ED symptoms tracked with pandemic-related concerns in people with EDs. Conceptualizing predictors of symptoms may inform therapy and public health resources that reduce the impact of pandemics on mental health. Public Significance: Our findings suggest that the COVID-19 pandemic had negative impacts on people with eating disorders, including amplification of mental health symptoms and stressors around peak periods of infection and COVID-19 restrictions. These findings inform medical providers, policy-makers, and community-based supports about the information and resource needs of this group to ensure efficient dissemination in future public health emergencies and during the ongoing COVID-19 pandemic

    Deaths due to differentiated thyroid cancer: A 46-year perspective

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    From 1940 to 1986, a total of 798 patients were treated for differentiated thyroid carcinoma. One hundred and seventy-two patients died during the follow-up period: 42 (24.4%) patients from thyroid cancer, 14 (8.1%) from other causes with extensive thyroid cancer present, 75 (43.6%) with no thyroid cancer, and 41 (23.8%) with an unknown status of thyroid cancer . Of the 42 patients dying due to thyroid cancer, 15 were male and 27, female. Mean age at diagnosis was 48.3±17.7 years with one-third of patients age 45 or younger at the time of the initial diagnosis. The primary tumors were large (>4 cm) and 59.5% of the patients had local invasion and/or cervical metastasis. Distant metastases were present in 9 (21.4%) patients at the time of diagnosis . Surgical therapy included total thyroidectomy (72.1%) and limited or radical neck dissection (69.4%). Radioactive iodine ( 131 I) was used to treat residual cancer and/or distant metastasis in 73.8% of the patients. External radiation therapy was used to treat locally advanced or recurrent disease in 52.3% of the patients. Distant metastases and local recurrence were identified earlier in patients with follicular thyroid cancer whose survival time and disease-free interval were significantly shorter ( p < 0.001) than that of patients with papillary neoplasms. However, the survival and disease-free intervals were often very long in both papillary and follicular thyroid cancer deaths . Onset of differentiated thyroid cancer before the age of 40 years does not preclude serious sequelae and death. Since no known histopathologic features can consistently predict outcome, we continue to advocate aggressive treatment of all patients with differentiated thyroid cancer . Entre 1940 et 1986, 798 patients au total ont été traités pour un cancer différencié de la thyroïde. Cent-soixant-douze patients sont morts par la suite: 42 (24.4%) de leur cancer, 14 (8.1%) d'une autre cause alors que des signes d'extension du cancer étaient présents, 75 (43.6%) d'une autre cause sans signe de cancer, et 41 (23.8%) sans qu'on ait pu connaître le stade du cancer. Des 42 patients morts de leur cancer, il y avait 15 hommes et 27 femmes. L'âge moyen au moment du diagnostic était de 48.3±17.7 ans: un tiers des patients avait 45 ans ou moins au moment du diagnostic. Les tumeurs primitives avaient plus de 4 cm et 59.5% des patients présentaient un envahissement local et/ou une métastase cervicale. Les métastases à distance ont été détectées chez 9 (21.4%) patients au moment du diagnostic. Une thyroïdectomie totale a été effectuée chez 72.1% des patients, associée à un curage cervical limité ou radical chez 69.4% des patients. Chez 73.8% des patients on a traité le tissu cancéreux résiduel et/ou des métastases à distance par de l'I 131. La radiothérapie a été utilisée pour traiter les patients présentant une extension importante ou une récidive chez 52.3% des patients. Des métastases à distance et des récidives ont été identifiées précocement chez les patients ayant un cancer folliculaire. Dans ce groupe de patients, la survie et l'intervalle de temps sans maladie étaient significativement plus courts ( p <0.001) que chez les patients ayant un cancer papillaire. Il faut cependant noter que la survie et l'intervalle de temps sans maladie étaient très longs dans les 2 groupes de patients. La découverte d'un cancer différencié de la thyroïde avant l'âge de 40 ans n'est pas un facteur pronostique particulier. Puisqu'il n'y pas de facteur histologique permettant de prévoir l'évolution, nous continuons de préconiser un traitement agressif chez tout patient présentant un cancer différencié de la thyroïde. En el período 1940–1986, un total de 798 pacientes recibieron tratamiento para carcinoma tiroideo; 172 murieron en el curso del seguimiento: 42 (24.4%) por cancer tiroideo, 14 (8.1%) por otras causas pero con presencia de extenso cáncer tiroideo, 75 (43.6%) libres de cáncer tiroideo, y 41 (23.8%) con estado desconocido en cuanto al cancer tiroideo.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41283/1/268_2005_Article_BF01655866.pd
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