1,184 research outputs found
Evaluating Process-Based Integrated Assessment Models of Climate Change Mitigation
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
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
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
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
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
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
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
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
ObjectiveThe 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). MethodParticipants 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. ResultsThree 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. DiscussionED 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 SignificanceOur 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.Stress-related psychiatric disorders across the life spa
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