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.
Temperate, polar and alpine insects generally do not feed over winter and hence must manage their energy stores to fuel their metabolism over winter and to meet the energetic demands of development ...and reproduction in the spring. In this Review, we give an overview of the accumulation, use and conservation of fat reserves in overwintering insects and discuss the ways insects modify fats to facilitate their selective consumption or conservation. Many insects are in diapause and have depressed metabolic rates over winter; together with low temperatures, this means that lipid stores are likely to be consumed predominantly in the autumn and spring, when temperatures are higher but insects remain dormant. Although there is ample evidence for a shift towards less-saturated lipids in overwintering insects, switches between the use of carbohydrate and lipid stores during winter have not been well-explored. Insects usually accumulate cryoprotectants over winter, and the resulting increase in haemolymph viscosity is likely to reduce lipid transport. For freeze-tolerant insects (which withstand internal ice), we speculate that impaired oxygen delivery limits lipid oxidation when frozen. Acetylated triacylglycerols remain liquid at low temperatures and interact with water molecules, providing intriguing possibilities for a role in cryoprotection. Similarly, antifreeze glycolipids may play an important role in structuring water and ice during overwintering. We also touch on the uncertain role of non-esterified fatty acids in insect overwintering. In conclusion, lipids are an important component of insect overwintering energetics, but there remain many uncertainties ripe for detailed exploration.
The cost of generating force hypothesis proposes that the metabolic rate during running is determined by the rate of muscle force development (1/t
, t
=contact time) and the volume of active leg ...muscle. A previous study assumed a constant recruited muscle volume and reported that the rate of force development alone explained ∼70% of the increase in metabolic rate for human runners across a moderate velocity range (2-4 m s
). We hypothesized that over a wider range of velocities, the effective mechanical advantage (EMA) of the lower limb joints would overall decrease, necessitating a greater volume of active muscle recruitment. Ten high-caliber male human runners ran on a force-measuring treadmill at 8, 10, 12, 14, 16 and 18 km hr
while we analyzed their expired air to determine metabolic rates. We measured ground reaction forces and joint kinematics to calculate contact time and estimate active muscle volume. From 8 to 18 km hr
, metabolic rate increased 131% from 9.28 to 21.44 W kg
Contact time (t
) decreased from 0.280 sec to 0.190 sec, and thus the rate of force development (1/t
) increased by 48%. Ankle EMA decreased by 19.7±11%, knee EMA increased by 11.1±26.9% and hip EMA decreased by 60.8±11.8%. Estimated active muscle volume per leg increased 52.8% from 1663±152 cm
to 2550±169 cm
Overall, 98% of the increase in metabolic rate across the velocity range was explained by just two factors: the rate of generating force and the volume of active leg muscle.
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.
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.
•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.
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.
Microporous polymers have transformed the field of membrane-based gas separations over the past two decades. However, applying sorbent materials as membranes presents a unique challenge in ...quantifying emergent phenomena, such as how strongly sorbing penetrants influence transport of co-permeating species. These mechanistic features are of urgent concern for many current and emerging applications, yet they remain significantly understudied. In previous work, amine-functionalized PIM-1 (PIM-NH2) has proven to be an exemplar of these effects, exhibiting CO2/CH4 mixed-gas selectivities that are 2.6 times higher than selectivities calculated from pure-gas measurements. Here, we investigate the generalizability of this sorption-induced emergent phenomena through the synthesis of a novel amine-functional microporous poly(arylene ether) (PAE-NH2). The effects of amine functionalization on gas transport were analyzed through variable-temperature pure-gas sorption tests, ternary mixed-gas sorption modeling, and dual-mode sorption analysis for N2, CH4, CO2, and H2S. Compared to its nitrile-functional counterpart (PAE-CN), pure-gas sorption for PAE-NH2 was 69 % higher for CO2 and 26 % higher for H2S at 1 atm and 35 °C, suggesting increased affinity to both CO2 and H2S. However, the higher total sorption for H2S resulted in strong competitive sorption effects, decreasing permeability of both CO2 and CH4 for mixture experiments, which was reported in our complementary study on the mixed-gas separation performance of the same materials in this work. The strength of gas–polymer interactions were quantified by evaluating experimental isosteric heats of sorption for the acid gases in PIM-1, PIM-NH2, PAE-CN, and PAE-NH2. Amine-functionalized samples showed highly exothermic interactions, with minima in isosteric heats of approximately −44 kJ mol−1 for CO2 and −34 kJ mol−1 for H2S. Leveraging microporosity and amine-functionality in membranes are general approaches to access competitive sorption for many industrially relevant gas separations.
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•Amine-functionalization of microporous poly(arylene ether) (PAE-CN) into PAE-NH2 was successful in solid-state.•High-pressure H2S, CO2, CH4, and N2 sorption isotherms were collected.•High-precision dual-mode sorption (DMS) modeling was used to fit isotherms and calculate energetics of sorption.•Amine functionality enhanced H2S and CO2 uptake relative to nitrile-functional materials.
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.
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•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.
Liquid phase exfoliation is a commonly used method to produce 2D nanosheets from a range of layered crystals. However, such nanosheets display broad size and thickness distributions and correlations ...between area and thickness, issues that limit nanosheet application potential. To understand the factors controlling the exfoliation process, we have liquid-exfoliated 11 different layered materials, size-selecting each into fractions before using AFM to measure the nanosheet length, width, and thickness distributions for each fraction. The resultant data show a clear power-law scaling of nanosheet area with thickness for each material. We have developed a simple nonequilibrium thermodynamics-based model predicting that the power-law prefactor is proportional to both the ratios of in-plane-tearing/out-of-plane-peeling energies and in-plane/out-of-plane moduli. By comparing the experimental data with the modulus ratio calculated from first-principles, we find close agreement between experiment and theory. This supports our hypothesis that energy equipartition holds between nanosheet tearing and peeling during sonication-assisted exfoliation.
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