A traditional metric used in hydrology to summarize model
performance is the Nash–Sutcliffe efficiency (NSE). Increasingly an
alternative metric, the Kling–Gupta efficiency (KGE), is used instead. ...When
NSE is used, NSE = 0 corresponds to using the mean flow as a benchmark
predictor. The same reasoning is applied in various studies that use KGE as
a metric: negative KGE values are viewed as bad model performance, and only
positive values are seen as good model performance. Here we show that using
the mean flow as a predictor does not result in KGE = 0, but instead KGE =1-√2≈-0.41. Thus, KGE values greater than −0.41
indicate that a model improves upon the mean flow benchmark – even if the
model's KGE value is negative. NSE and KGE values cannot be directly
compared, because their relationship is non-unique and depends in part on
the coefficient of variation of the observed time series. Therefore,
modellers who use the KGE metric should not let their understanding of NSE
values guide them in interpreting KGE values and instead develop new
understanding based on the constitutive parts of the KGE metric and the
explicit use of benchmark values to compare KGE scores against. More
generally, a strong case can be made for moving away from ad hoc use of
aggregated efficiency metrics and towards a framework based on
purpose-dependent evaluation metrics and benchmarks that allows for more
robust model adequacy assessment.
Biologists have developed a wide range of morphological, biochemical and physiological metrics to assess the health and, in particular, the energetic status of individual animals. These metrics ...originated to quantify aspects of human health, but have also proven useful to address questions in life history, ecology and resource management of game and commercial animals. We review the application of condition indices (CI) for conservation studies and focus on measures that quantify fat reserves, known to be critical for energetically challenging activities such as migration, reproduction and survival during periods of scarcity. Standard methods score fat content, or rely on a ratio of body mass rationalized by some measure of size, usually a linear dimension such as wing length or total body length. Higher numerical values of these indices are interpreted to mean an animal has greater energy reserves. Such CIs can provide predictive information about habitat quality and reproductive output, which in turn can help managers with conservation assessments and policies. We review the issues about the methods and metrics of measurement and describe the linkage of CIs to measures of body shape. Debates in the literature about the best statistical methods to use in computing and comparing CIs remain unresolved. Next, we comment on the diversity of methods used to measure body composition and the diversity of physiological models that compute body composition and CIs. The underlying physiological regulatory systems that govern the allocation of energy and nutrients among compartments and processes within the body are poorly understood, especially for field situations, and await basic data from additional laboratory studies and advanced measurement systems including telemetry. For now, standard physiological CIs can provide supporting evidence and mechanistic linkages for population studies that have traditionally been the focus of conservation biology. Physiologists can provide guidance for the field application of conditions indices with validation studies and development of new instruments.
Highlights • A review of technical aspects of transcranial electrical stimulation (tES) techniques. • Recommendations for safe and replicable application of tDCS and other tES methods. • Discussion ...of state-of-the-art methodology and design considerations in tES.
PURPOSEExercise is associated with altered gut microbial composition, but studies have not investigated whether the gut microbiota and associated metabolites are modulated by exercise training in ...humans. We explored the impact of 6 wk of endurance exercise on the composition, functional capacity, and metabolic output of the gut microbiota in lean and obese adults with multiple-day dietary controls before outcome variable collection.
METHODSThirty-two lean (n = 18 9 female) and obese (n = 14 11 female), previously sedentary subjects participated in 6 wk of supervised, endurance-based exercise training (3 d·wk) that progressed from 30 to 60 min·d and from moderate (60% of HR reserve) to vigorous intensity (75% HR reserve). Subsequently, participants returned to a sedentary lifestyle activity for a 6-wk washout period. Fecal samples were collected before and after 6 wk of exercise, as well as after the sedentary washout period, with 3-d dietary controls in place before each collection.
RESULTSβ-diversity analysis revealed that exercise-induced alterations of the gut microbiota were dependent on obesity status. Exercise increased fecal concentrations of short-chain fatty acids in lean, but not obese, participants. Exercise-induced shifts in metabolic output of the microbiota paralleled changes in bacterial genes and taxa capable of short-chain fatty acid production. Lastly, exercise-induced changes in the microbiota were largely reversed once exercise training ceased.
CONCLUSIONThese findings suggest that exercise training induces compositional and functional changes in the human gut microbiota that are dependent on obesity status, independent of diet and contingent on the sustainment of exercise.
Abstract Physiological conversion of the maternal spiral arteries is key to a successful human pregnancy. It involves loss of smooth muscle and the elastic lamina from the vessel wall as far as the ...inner third of the myometrium, and is associated with a 5–10-fold dilation at the vessel mouth. Failure of conversion accompanies common complications of pregnancy, such as early-onset preeclampsia and fetal growth restriction. Here, we model the effects of terminal dilation on inflow of blood into the placental intervillous space at term, using dimensions in the literature derived from three-dimensional reconstructions. We observe that dilation slows the rate of flow from 2 to 3 m/s in the non-dilated part of an artery of 0.4–0.5 mm diameter to approximately 10 cm/s at the 2.5 mm diameter mouth, depending on the exact radius and viscosity. This rate predicts a transit time through the intervillous space of approximately 25 s, which matches observed times closely. The model shows that in the absence of conversion blood will enter the intervillous space as a turbulent jet at rates of 1–2 m/s. We speculate that the high momentum will damage villous architecture, rupturing anchoring villi and creating echogenic cystic lesions as evidenced by ultrasound. The retention of smooth muscle will also increase the risk of spontaneous vasoconstriction and ischaemia–reperfusion injury, generating oxidative stress. Dilation has a surprisingly modest impact on total blood flow, and so we suggest the placental pathology associated with deficient conversion is dominated by rheological consequences rather than chronic hypoxia.
The gastrointestinal tract contains trillions of microbes (collectively known as the gut microbiota) that play essential roles in host physiology and health. Studies from our group and others have ...demonstrated that exercise independently alters the composition and functional capacity of the gut microbiota. Here, we review what is known about the gut microbiota, how it is studied, and how it is influenced by exercise training and discuss the potential mechanisms and implications for human health and disease.
′The theory and practice of democracy and democratic leadership have implications for how we understand what ought to be counted as ′improving schools′′ In this book the author focuses on the idea of ...democratic leadership. He examines what is meant by democratic leadership, and what forms it can take, and shows how it is relevant to school education and learning. The author shows how the ideals and theories of democratic leadership can translate into practice, and sets out some of the challenges posed by democratic leadership in the context of contemporary education.
In December 2019, the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group (V-MOD) adopted the thirteenth generation of the International Geomagnetic Reference Field ...(IGRF). This IGRF updates the previous generation with a definitive main field model for epoch 2015.0, a main field model for epoch 2020.0, and a predictive linear secular variation for 2020.0 to 2025.0. This letter provides the equations defining the IGRF, the spherical harmonic coefficients for this thirteenth generation model, maps of magnetic declination, inclination and total field intensity for the epoch 2020.0, and maps of their predicted rate of change for the 2020.0 to 2025.0 time period.
Microglia play a vital role maintaining brain homeostasis but can also cause persistent neuroinflammation. Short-chain fatty acids (SCFAs) produced by the intestinal microbiota have been suggested to ...regulate microglia inflammation indirectly by signaling through the gut-brain axis or directly by reaching the brain. The present work evaluated the anti-inflammatory effects of SCFAs on lipopolysaccharide (LPS)-stimulated microglia from mice fed inulin, a soluble fiber that is fermented by intestinal microbiota to produce SCFAs in vivo, and SCFAs applied to primary microglia in vitro. Feeding mice inulin increased SCFAs in the cecum and in plasma collected from the hepatic portal vein. Microglia isolated from mice fed inulin and stimulated with LPS in vitro secreted less tumor necrosis factor α (TNF-α) compared to microglia from mice not given inulin. Additionally, when mice were fed inulin and injected i.p with LPS, the ex vivo secretion of TNF-α by isolated microglia was lower than that secreted by microglia from mice not fed inulin and injected with LPS. Similarly, in vitro treatment of primary microglia with acetate and butyrate either alone or in combination downregulated microglia cytokine production with the effects being additive. SCFAs reduced histone deacetylase activity and nuclear factor-κB nuclear translocation after LPS treatment in vitro. Whereas microglia expression of SCFA receptors Ffar2 or Ffar3 was not detected by single-cell RNA sequencing analysis, the SCFA transporters Mct1 and Mct4 were. Nevertheless, inhibiting monocarboxylate transporters on primary microglia did not interfere with the anti-inflammatory effects of SCFAs, suggesting that if SCFAs produced in the gut regulate microglia directly it is likely through an epigenetic mechanism following diffusion.
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