The proton thermal energetics in the slow solar wind between 0.3 and 1 AU is reinvestigated using the Helios 1 and 2 data, complementing a similar analysis for the fast solar wind Hellinger et al., ...2011. The results for slow and fast solar winds are compared and discussed in the context of previous results. Protons need to be heated in the perpendicular direction with respect to the ambient magnetic field from 0.3 to 1 AU. In the parallel direction, protons need to be cooled at 0.3 AU, with a cooling rate comparable to the corresponding perpendicular heating rate; between 0.3 and 1 AU, the required cooling rate decreases until a transition to heating occurs: by 1 AU the protons require parallel heating, with a heating rate comparable to that required to sustain the perpendicular temperature. The heating/cooling rates (per unit volume) in the fast and slow solar winds are proportional to the ratio between the proton kinetic energy and the expansion time. On average, the protons need to be heated and the necessary heating rates are comparable to the energy cascade rate of the magnetohydrodynamic turbulence estimated from the stationary Kolmogorov‐Yaglom law at 1 AU; however, in the expanding solar wind, the stationarity assumption for this law is questionable. The turbulent energy cascade may explain the average proton energetics (although the stationarity assumption needs to be justified) but the parallel cooling is likely related to microinstabilities connected with the structure of the proton velocity distribution function. This is supported by linear analysis based on observed data and by results of numerical simulations.
Key Points
Proton heating/cooling rates in the solar wind are estimatedHeating rates comparable to estimated turbulent energy cascade ratesObserved parallel cooling likely due to kinetic processes
ABSTRACT
Winter is a key driver of individual performance, community composition, and ecological interactions in terrestrial habitats. Although climate change research tends to focus on performance ...in the growing season, climate change is also modifying winter conditions rapidly. Changes to winter temperatures, the variability of winter conditions, and winter snow cover can interact to induce cold injury, alter energy and water balance, advance or retard phenology, and modify community interactions. Species vary in their susceptibility to these winter drivers, hampering efforts to predict biological responses to climate change. Existing frameworks for predicting the impacts of climate change do not incorporate the complexity of organismal responses to winter. Here, we synthesise organismal responses to winter climate change, and use this synthesis to build a framework to predict exposure and sensitivity to negative impacts. This framework can be used to estimate the vulnerability of species to winter climate change. We describe the importance of relationships between winter conditions and performance during the growing season in determining fitness, and demonstrate how summer and winter processes are linked. Incorporating winter into current models will require concerted effort from theoreticians and empiricists, and the expansion of current growing‐season studies to incorporate winter.
Un contact vibratoire avec les éléments Claire Revol; Pascaline Thiollière; Sébastien de Pertat ...
Socio-anthropologie,
12/2023, Letnik:
48
Journal Article
Recenzirano
Odprti dostop
This contribution looks at occidental geomancy practices called « geobiology », based on a survey initiated in 2020 in the Alpine region around the Grenoble urban region. Geobiology refers to a set ...of ways of feeling that are attentive to terrestrial, telluric and cosmic energies, mobilized for the purpose of caring for humans and animals or harmonizing the habitat. Based on a few examples of how we come into contact with these phenomena mobilizing different modalities of internal senses and somatic experience, we’ll show that they involve cosmologies that situate human beings between sky and earth, and manifest themselves in sensitive relationships with living environments.
Background
Nonalcoholic fatty liver disease (NAFLD) is linked to a raised risk of cardiovascular diseases (CVD), although the underlying mechanisms are not completely known. A reduced myocardial ...mechano‐energetic efficiency (MEE) has been found to be an independent predictor of CVD.
Objective
To evaluate the association between NAFLD and a compromised MEE.
Methods
Myocardial MEE was assessed by a validated echocardiography‐derived measure in 699 nondiabetic individuals subdivided into two groups according to ultrasonography defined presence of NAFLD.
Results
Subjects with NAFLD displayed higher levels of systolic (SBP) and diastolic blood pressure (DBP), triglycerides, fasting and postload glucose, high‐sensitivity C‐reactive protein (hsCRP), insulin resistance (IR) estimated by HOMA‐IR and liver IR index, and lower values of high‐density lipoprotein (HDL) in comparison with those without NAFLD. Presence of NAFLD was associated with increased levels of myocardial oxygen demand and reduced values of MEE. MEE was negatively correlated with male sex, age, BMI, waist circumference, SBP, DBP, total cholesterol, triglycerides, fasting and postload glucose, HOMA‐IR and liver IR index, hsCRP and positively with HDL levels. In a multivariable regression analysis, presence of NAFLD was associated with MEE regardless of several cardio‐metabolic risk factors such as age, gender, waist circumference, SBP, DBP, total and HDL cholesterol, triglycerides, glucose tolerance and hsCRP (β = −0.09, P = 0.04), but not independently of IR estimates.
Conclusion
Ultrasound‐defined presence of NAFLD is associated with a decreased MEE, a predictor of adverse cardiovascular events. The relationship between NAFLD and a compromised MEE is dependent of IR.
Elevated temperatures and low aquatic oxygen levels are increasingly accompanying climate warming and can adversely affect the production and welfare of farmed fish. Both environmental factors and ...diet affect fish energetics. Still, little is known about the dietary effects on fish energetics at elevated temperatures and low aquatic oxygen levels and how that influences growth. Thus, a feeding trial was conducted to investigate the effect of two isoenergetic diets, high protein (HP, 57% crude protein and 9% total lipid) and high lipid (HL, 40% crude protein and 19% total lipid), on juvenile barramundi (Lates calcarifer, initial body mass: ∼ 3 g). Fish were acclimated for at least four weeks on the diets (three weeks at 35 °C) before measurements began (i.e.: measurements were taken between weeks four to six of the trial). Additionally, feed intake and maximum metabolic rate were tested under three levels of aquatic oxygen levels (normoxia >80, 60% and 30% air saturation). We found no significant dietary effect on feed intake, routine, maximum and postprandial peak metabolic rate. Gill ventilation rate was also unaffected by diet treatment. However, fish fed the HP diet had increased haematocrit and haemoglobin levels, improved growth rates, feed conversion ratio, and protein deposition relative to those fed the HL diet. Thus, this study demonstrated that a high protein diet enhanced key physiological traits such as oxygen-carrying capacity, potentially supporting improved juvenile barramundi growth at elevated temperatures.
•Barramundi had an increased oxygen-carrying capacity when fed a high protein diet.•A high protein diet improved growth rates but not metabolic rate performance.•Acute hypoxia but not diet impacted maximum metabolic rate and feed intake at 35 °C.
We present the revM06-L functional, which we designed by optimizing against a larger database than had been used for Minnesota 2006 local functional (M06-L) and by using smoothness restraints. The ...optimization strategy reduced the number of parameters from 34 to 31 because we removed some large terms that increased the required size of the quadrature grid and the number of self-consistent-field iterations. The mean unsigned error (MUE) of revM06-L on 422 chemical energies is 3.07 kcal/mol, which is improved from 3.57 kcal/mol calculated by M06-L. The MUE of revM06-L for the chemical reaction barrier height database (BH76) is 1.98 kcal/mol, which is improved by more than a factor of 2 with respect to the M06-L functional. The revM06-L functional gives the best result among local functionals tested for the noncovalent interaction database (NC51), with an MUE of only 0.36 kcal/mol, and the MUE of revM06-L for the solid-state lattice constant database (LC17) is half that for M06-L. The revM06-L functional also yields smoother potential curves, and it predicts more-accurate results than M06-L for seven out of eight diversified test sets not used for parameterization. We conclude that the revM06-L functional is well suited for a broad range of applications in chemistry and condensed-matter physics.
•Intraseasonal fluctuations in the abyssal South China Sea are characterized.•The variabilities are closely related to topographic and planetary Rossby waves.•Surface perturbations serve as the major ...energy source for the deep fluctuations.•Energy is radiated across layers through pressure work and damped by dissipation.•This study highlights a universality in the intraseasonal energetics of deep ocean.
Energetics of the abyssal ocean account greatly for the redistribution and dissipation of global oceanic energy. In this study, we characterize the intraseasonal fluctuations in the deep South China Sea (SCS) and evaluate the relevant energy budget using observations and numerical simulations. The results indicate substantial geographical inhomogeneity in the intraseasonal energy reservoir. The high-energy zones are located in the northwest of the Luzon Strait, northern slopes, deep western boundary current region, and southwestern cyclonic gyre region, where the intraseasonal fluctuations account for about 70% of the deep energy variability. Vorticity and divergence patterns of the intraseasonal motions are suggestive of quasigeostrophic dynamics, which are mostly attributed to the hybrid topographic–planetary Rossby waves. The flow field exhibits a weak lateral shear and appears to have symmetric instability with negative vorticity skewness, particularly over the sloping topography. Energetics analysis demonstrates that the intraseasonal fluctuations in the abyssal SCS obtain energy primarily from the upper layer through pressure work, while secondarily from advective transport and cross-scale transfer due to instability of the deep circulation. To reach equilibrium, the energy gained is mostly damped by dissipations. As another reference in the marginal sea with intensive mixing, our study highlights the potential universality in how the intraseasonal energy is fueled and dissipated in the abyss.
Bighorn sheep (Ovis canadensis) can live in extremely harsh environments and subsist on submaintenance diets for much of the year. Under these conditions, energy stored as body fat serves as an ...essential reserve for supplementing dietary intake to meet metabolic demands of survival and reproduction. We developed equations to predict ingesta-free body fat in bighorn sheep using ultrasonography and condition scores in vivo and carcass measurements postmortem. We then used in vivo equations to investigate the relationships between body fat, pregnancy, overwinter survival, and population growth in free-ranging bighorn sheep in California and Nevada. Among 11 subpopulations that included alpine winter residents and migrants, mean ingesta-free body fat of lactating adult females during autumn ranged between 8.8% and 15.0%; mean body fat for nonlactating females ranged from 16.4% to 20.9%. In adult females, ingesta-free body fat > 7.7% during January (early in the second trimester) corresponded with a > 90% probability of pregnancy and ingesta-free body fat > 13.5% during autumn yielded a probability of overwinter survival > 90%. Mean ingesta-free body fat of lactating females in autumn was positively associated with finite rate of population increase (λ) over the subsequent year in bighorn sheep subpopulations that wintered in alpine landscapes. Bighorn sheep with ingesta-free body fat of 26% in autumn and living in alpine environments possess energy reserves sufficient to meet resting metabolism for 83 days on fat reserves alone. We demonstrated that nutritional condition can be a pervasive mechanism underlying demography in bighorn sheep and characterizes the nutritional value of their occupied ranges. Mountain sheep are capital survivors in addition to being capital breeders, and because they inhabit landscapes with extreme seasonal forage scarcity, they also can be fat reserve obligates. Quantifying nutritional condition is essential for understanding the quality of habitats, how it underpins demography, and the proximity of a population to a nutritional threshold.
Neurons require mechanisms to maintain ATP homeostasis in axons, which are highly vulnerable to bioenergetic failure. Here, we elucidate a transcellular signaling mechanism by which oligodendrocytes ...support axonal energy metabolism via transcellular delivery of NAD-dependent deacetylase SIRT2. SIRT2 is undetectable in neurons but enriched in oligodendrocytes and released within exosomes. By deleting sirt2, knocking down SIRT2, or blocking exosome release, we demonstrate that transcellular delivery of SIRT2 is critical for axonal energy enhancement. Mass spectrometry and acetylation analyses indicate that neurons treated with oligodendrocyte-conditioned media from WT, but not sirt2-knockout, mice exhibit strong deacetylation of mitochondrial adenine nucleotide translocases 1 and 2 (ANT1/2). In vivo delivery of SIRT2-filled exosomes into myelinated axons rescues mitochondrial integrity in sirt2-knockout mouse spinal cords. Thus, our study reveals an oligodendrocyte-to-axon delivery of SIRT2, which enhances ATP production by deacetylating mitochondrial proteins, providing a target for boosting axonal bioenergetic metabolism in neurological disorders.
Display omitted
•Oligodendrocyte-to-neuron signaling enhances axonal mitochondria ATP production•Elevating neuronal deacetylase SIRT2 facilitates mitochondria ATP production•SIRT2 is transcellularly delivered from oligodendrocytes to axons via exosomes•In vivo delivery of OL-EXOs rescues axonal mitochondrial integrity in spinal cords
Neurons require mechanisms to maintain axonal ATP. Chamberlain et al. identify an exosome-mediated transcellular pathway through which oligodendrocyte-derived sirtuin 2 is delivered to axons, enhancing bioenergetics by deacetylation of mitochondrial proteins for increased ATP generation. Revealing this pathway advances understanding of axonal energy maintenance in health and neurological disorders.
PDF
