Total Energy Reserves Research Articles

A wind farm control strategy for frequency regulation reserve: Optimize wake loss and frequency support capability

—With a high proportion of renewable energy, the issue of grid frequency fluctuations is becoming increasingly prominent. To tackle this challenge, wind farms can enhance frequency regulation response by increasing rotational kinetic energy through overspeed control. However, this approach may result in energy losses due to the wake effect. This paper proposes an optimized configuration strategy for wind farm frequency regulation reserve (FRR), utilizing pitch angle cooperative control to reduce wake losses. The objective is to explore the optimal configuration for maximizing wind energy utilization under FRR conditions. A genetic algorithm is used to find the optimal control parameters in the established FLORIS-based wind farm power reserve wake model, which involves rotor speed and pitch angle control, to maximize output power and rotational kinetic energy. Based on this, a lookup table is constructed to map wind conditions to the optimal control parameters for different FRR level. According to the reserve power schedule, optimization control is applied to the wind farm. Simulation results show that, compared to the traditional equal distribution strategy for FRR power, the proposed control strategy can enhance the total kinetic energy reserve of the wind farm by optimizing wake loss, thereby improving frequency support capability.

Sex-specific trade-off under marine heat wave and food limitation: Insights from bioenergetic and intestinal microbiome in mussels

Global warming, marine heat waves and subsequent food limitation are projected to be more frequent and intense under future climate change. Understanding the consequences for key marine species such as mussels is critical to ensure sustainability and guide adaptation options. Mussels are not only an economically important species but also considered excellent indicators of environmental changes. This study evaluates the sex-specific effects of marine heat waves and food limitation on the bioenergetics and intestinal flora of the digestive glands of mussels. Heat waves had a significant negative effect on cell energy homeostasis of the digestive gland in female mussels. Food limitation significantly decreased the total energy reserve in the digestive gland of both female and male mussels. Combined food limitation and heat wave led to sex-specific responses with significantly higher cellular energy allocation parameters observed in the digestive gland of female mussels as compared to males. Additionally, 16S rRNA sequencing showed that the intestinal flora of female mussels was more stable, as well as sex-specific differences in the relative abundance of various bacteria phyla. This study highlights the importance to consider sex in studies evaluating the impact of climate change in mussels, and the results can contribute to the development of strategies for sustainable bivalve aquaculture under the growing risks of warming, heatwaves and food limitations.

Long‐term effects of elevated CO2 on the nutrition provided to parasitoids by their herbivorous hosts

AbstractElevated concentrations of atmospheric carbon dioxide (CO2), a consequence of anthropogenic global change, may profoundly interfere with natural ecological processes, perhaps even interactions across trophic levels. Even the survival prospects of organisms at higher trophic levels could be affected, as follows. We showed previously that the endoparasitoid Diaeretiella rapae, a specialized parasitoid of the cabbage aphid Brevicoryne brassicae, exposed to elevated CO2 concentrations (800 ppm) for up to 10 weeks, performed far worse (e.g., lower survival and parasitism rates) compared with ambient CO2 (400 ppm). To investigate whether these CO2‐related effects in the parasitoids were mediated by changes in the quality of the aphids as hosts, we measured the nutritional and energy content of cabbage aphids under the above conditions. Specifically, we measured lipid, protein and water‐soluble carbohydrate concentrations. We tested the hypothesis that when insects feed from plants with altered nutritional content, they incur a cost in dealing with such biotic stresses. That cost reduces their metabolic well‐being and, thus, reduces their nutritional status with respect to parasitoids developing at their expense. We found that CO2 had significant effects on aphid body mass (i.e., wet weight) and chemical composition, with elevated CO2 concentrations reducing aphid mass by more than 50%. Aphids grown under elevated CO2 also had significantly reduced soluble carbohydrates but significantly more lipids, on a weight‐per‐weight basis, than aphids grown under ambient CO2. A significant decrease in total energy reserves (i.e., the sum of total proteins, lipids, and water‐soluble carbohydrates) thus typified aphids grown under elevated CO2. Our results contribute to explaining the impaired performance of the aphid B. brassicae and its parasitoid D. rapae previously reported under elevated CO2, and provide evidence that under future climate change, host plants might affect the development and performance of parasitoids through their impacts on the nutritional quality of their herbivorous hosts.

Cold-water coral energy reserves and calcification in contrasting fjord environments

The relationship between energy reserves of cold-water corals (CWCs) and their physiological performance remains largely unknown. In addition, it is poorly understood how the energy allocation to different metabolic processes might change with projected decreasing food supply to the deep sea in the future. This study explores the temporal and spatial variations of total energy reserves (proteins, carbohydrates and lipids) of the CWC Desmophyllum dianthus and their correlation with its calcification rate. We took advantage of distinct horizontal and vertical physico-chemical gradients in Comau Fjord (Chile) and examined the changes in energy reserves over one year in an in situ reciprocal transplantation experiment (20 m vs. 300 m and fjord head vs. mouth). Total energy reserves correlated positively with calcification rates. The fast-growing deep corals had higher and less variable energy reserves, while the slower-growing shallow corals showed pronounced seasonal changes in energy reserves. Novel deep corals (transplanted from shallow) were able to quickly increase both their calcification rates and energy reserves to similar levels as native deep corals. Our study shows the importance of energy reserves in sustaining CWC growth in spite of aragonite undersaturated conditions (deep corals) in the present, and potentially also future ocean.

Numerical simulation of the thermal response of seabed sediments to geothermal cycles in Suvilahti, Finland

Renewable thermal energy from seabed sediment is used for heating and cooling houses in Suvilahti, Vaasa, Finland. Innovative coaxial polyethylene pipes (Refla) filled with heat collection fluid are laid horizontally in the sediment layer. This study aims to evaluate the adequacy and possible overuse of this shallow geothermal energy. This entailed a numerical analysis of the heat relations of a “coaxial closed-loop geothermal system (CCGS)" to investigate the thermal behavior of the sediment. The numerical model was developed in Midas GTS NX software with a thermal analysis module. The objective was to understand temperature fluctuation in the sediment, which is influenced not only by geothermal energy exploitation, but also by seasonal weather. The numerical model, due to its design, provided information mainly about changes in sediment temperature due to the geothermal energy exploitation during the different seasons. The results show that in the first third of the total length of the Refla pipes, the sediment environment is significantly affected by energy exploitation's temperature loading. It is advisable to exclude the first third from an analysis of total geothermal energy reserves. The remaining two-thirds of the length shows potential to provide sustainable, long-term geothermal energy (GE) exploitation at the current rate.

Changes in energy reserves and responses of some biomarkers in freshwater mussels exposed to metal-oxide nanoparticles

In this study, responses of various biomarkers in the digestive gland and foot muscle of freshwater mussels (Unio tigridis) were investigated following exposure to Al2O3, CuO and TiO2 nanoparticles (NPs) for 14 days at different concentrations (0, 1, 3 and 9 mg NP/L). Mussels were fed on unicellular algae (Chlorella vulgaris) cultured in the laboratory. NP exposures caused significant increases (p < 0.05) in the levels of total glutathione (GSH), reduced-glutathione (rGSH), oxidized-glutathione (GSSG) and malondialdehyde (MDA) in the digestive gland. Oppositely, there were significant (p < 0.05) decreases in acetylcholinesterase activity in the foot muscles. Total energy reserves of the digestive gland and foot muscle significantly (p < 0.05) decreased, but only at the highest NP exposures. Nevertheless, NP exposures did not alter (p > 0.05) the algae filtering capacity of mussels. This study demonstrated that the biomarkers belonging to different metabolic systems responded to NP exposures, suggesting their usage in the monitoring studies for freshwater systems.

Distinct stages of the intestinal bacterial community of Ampullaceana balthica after salinization.

Environmental disturbances influence bacterial community structure and functioning. To investigate the effect of environmental disturbance caused by changes in salinity on host-protected bacterial communities, we analyzed the microbiome within the gastrointestinal tract of Ampullaceana balthica in different salinities. A. balthica is a benthic gastropod found in fresh- and mesohaline waters. Whereas the total energy reserves of A. balthica were unaffected by an increase of salinity to 3, a high mortality rate was detected after a shift from freshwater to salinity 6 suggesting a major disruption of energy homeostasis. The shift to salinity 6 also caused a change in the gastrointestinal bacterial community composition. At salinity 3, the bacterial community composition of different host individuals was related either to the freshwater or salinity 6 gastrointestinal bacterial community, indicating an ambivalent nature of salinity 3. Since salinity 3 represents the range where aquatic gastropods are able to regulate their osmolarity, this may be an important tipping point during salinization. The change in the intestinal microbiome was uncoupled from the change in the water bacterial community and unrelated to the food source microbiome. Our study shows that environmental disturbance caused by salinity acts also on the host-protected microbiome. In light of the sea-level rise, our findings indicate that salinization of the near-shore freshwater bodies will cause changes in organisms’ intestinal microbiomes if a critical salinity threshold (presumably ∼3) is exceeded.

Laboratory study of a hydronic concrete deck heated externally in a controlled sub-freezing environment

Geothermal heating of bridge decks is a reliable and sustainable method for bridge de-icing that has been increasing in demand since conventional de-icing methods were proved to be environmentally hazardous. Previous research on geothermal heating of bridge decks relied on hydronic pipes embedded inside of bridge decks, which are confined to newly constructed bridges. For existing bridges, a newly devised method for external heating has been recently tested under limited laboratory conditions to determine its overall performance. This study explores laboratory heating tests of a concrete slab with a thickness representing a typical concrete bridge deck. This slab was equipped with a simulated geothermal bridge de-icing system and tested inside a freezer subjected to sub-freezing controlled conditions. Various winter scenarios were applied to the system to determine its heating performance and how feasible it will be for the system to be transferred to the field. A prediction equation was developed to estimate the total energy reserves required to permit de-icing, and statistical analysis was performed and validated with test results. The slab surface heat flux was estimated to range from 27 W/m2K to 73 W/m2K from the heating test. The externally-heated deck can be designed with the developed prediction equation for snow melting.

Insights into the ecotoxicological perturbations induced by the biocide Abamectin in the white snail, Theba pisana

Abamectin (avermectin B1, ABM) has been widely used as a biocide in agriculture, veterinary and medicine around the world. Yet, there is still a lack of knowledge about the ecotoxicological effects of ABM. In this study, we investigated the acute toxicity and sub-lethal (20% and 60% LD50) biochemical responses of ABM on the non-target land snail, Theba pisana. Mortality of snails increased with the dose increase, resulting 48 h- LD50 value of 1.048 µg/snail. The biochemical results showed a decrease in glycogen content and lipids for two sub-lethal doses after all time intervals, whereas increased the level of total proteins after exposure to 60% LD50 ABM. Overall, the tested sub-lethal doses significantly decreased the total energy reserves. ABM-exposure to snails elevated γ-Glutamyl transferase and Lactate dehydrogenase activities at all-time intervals. A significant increase of Glutathione-S-transferase activity was also recorded in snails exposed to 20% and 60% LD50 after 7 days and all time intervals, respectively. However, ABM inhibited the activity of Aspartate aminotransferase and Alanine aminotransferase after 7 days of exposure. Our investigation provides new insights into the disturbances of energy reserves and enzyme activities in T. pisana that are sensitive and may be used as biomarkers for assessing ABM toxicity.

Emamectin benzoate as a potential molluscicide against white garden snail, Theba pisana in association with biochemical defects.

The white garden snail, Theba pisana, is distributed worldwide and is a serious molluscan pest of different crops. Emamectin benzoate (EMB) 'an avermectin derivative' is a novel biorational agent and highly effective pesticide. This study focused on the lethal and in vivo sublethal toxic effect of EMB on the energy reserves (glycogen, lipids and proteins), total energy reserves and activities of glutathione S-transferase (GST), γ-glutamyl transferase (γ-GT), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the hepatopancreas of T. pisana for up to 7 days of exposure. The median lethal dose (LD50 ) at 48 h of EMB treatment was 5.34 μg g-1 body weight (b.w.). Sublethal doses of 1.07 and 3.20 μg g-1 b.w. (i.e., 20% and 60% of the LD50 ) led to significant dose- and time-dependent decreases in glycogen and lipids; these doses increased the total protein level. Overall, the tested sublethal doses significantly decreased the total energy reserves. Moreover, GST and γ-GT activities were elevated, whereas the activities of AST and ALT were inhibited in the exposed snails. A decrease in LDH activity after 1 and 3 days of exposure and an increase after 7 days of exposure were seen in snails treated with EMB. EMB exerted lethal toxicity on T. pisana and consequently caused changes in energy reserve levels and enzyme activities in the animal. © 2022 Society of Chemical Industry.

Cellular Energy Allocation of Tuta absoluta (Lepidoptera: Gelechiidae) treated with Flubendiamide and Thiocyclam Hydrogen Oxalate on Different Tomato Cultivars

The tomato leaf miner, Tuta absoluta (Meyrick), is the most important pest for tomato production in Iran. The effect of flubendiamide and thiocyclam hydrogen oxalate insecticides was assessed on cellular energy allocation (CEA) of the third instar larvae of T. absoluta ingesting six different tomato cultivars. Plant leaves were treated with LC50 concentration of both insecticides and their energy available (Ea), energy consumption (Ec), and CEA were calculated. The results showed that total energy reserves (protein, carbohydrate, and lipid budgets) were significantly reduced after exposure to insecticides and tomato secondary metabolites. The larvae fed on Riogrande and Super Chief cultivars showed the least amount of energy available after treatment with both insecticides. The highest rate of oxygen consumption was observed in larvae fed on Calj, Super Luna, and Super strain B after treatment with flubendiamide. The amount of CEA decreased in treated larvae compared to untreated larvae. This reduction was statistically higher in treated larvae that fed on Riogrande and Super strain B cultivars. Reduction in CEA is probably due to the expenses of dealing with detoxification of insecticides and plant metabolites. CEA is a suitable and primary biomarker for the effects of cultivars and insecticides as integrate and summarizes insect energy allocation in variable situations.

Biochemical Composition and Energy Content in the Zooplankton of the Kara Sea

This article presents a data set on ash, proteins, lipids, carbohydrates, chitin, organic carbon (OC), total nitrogen (TN) and total phosphorus (TP) contents, macronutrients ratio (C, N, and P) and energy content of zooplankton (size fraction >500 μm) from the Kara Sea. Zooplankton samples were collected at 22 stations during the 76th interdisciplinary cruise of the R/V “Akademik Mstislav Keldysh” in July 2019. Proteins constituted the main component of zooplankton dry weight (43.39 ± 2.57% DW), while lipids amounted to 26.67 ± 2.28% DW and carbohydrates reached 4.91 ± 0.49% DW. Ash and chitin contents were 18.78 ± 1.39% and 3.68 ± 0.37% DW, respectively. The concentrations of macronutrients (C, N, and P) corresponded to the values of Arctic zooplankton and averaged 47.52 ± 1.12% for OC, 7.34 ± 0.39% for TN, and 0.70 ± 0.04% for TP of DW. The contribution of the individual components of the biochemical composition of zooplankton of the Kara Sea to the total OC revealed the dominant role of not only lipids but also proteins as compounds used by zooplankton in organic carbon accumulation. The Redfield ratio varied widely. The average values of C6.6:N, C70:P and N10.5:P were low and reflected certain features of the biochemical composition of the Kara Sea zooplankton community in the spring. The energy content of zooplankton of the Kara Sea ranged from 18.3 to 25.58 J mg-1 and averaged 20.25 ± 0.53 J mg-1 DW. The proportions of lipids and proteins in the total energy reserve of zooplankton were ~47 and ~46%, respectively, while the share of carbohydrates, their derivatives and chitin amounted to ~7%.

Energy reserves and respiration rate in the earthworm Eisenia andrei after exposure to zinc in nanoparticle or ionic form.

The energy budget is an indicator of an organism’s overall condition. Changes in energy reserves and/or energy consumption have been used as biomarkers of toxic stress. To understand the effects of different forms and concentrations of Zn and the costs of effective Zn regulation by the earthworm Eisenia andrei, we performed a toxicokinetic experiment in which individuals were sampled over time to determine the available energy reserves (total carbohydrate, protein, and lipid content), energy consumption (measured at the cellular level and as the whole-animal respiration rate), and internal Zn concentration. The earthworms were exposed to ZnCl2 or zinc nanoparticles (ZnO-NPs) in Lufa 2.2 soil for 21 days (contamination phase), followed by 14 days of elimination in clean soil (decontamination phase). Carbohydrates were the only energy reserves with significantly lower levels following ZnO-NP 1000 treatment than following other treatments (p ≤ 0.00001) in the contamination phase. The total available energy reserves and protein content did not differ among treatments, but a significant effect of exposure time was observed (p ≤ 0.0001). Exposure to Zn (both ions and NPs) increased energy consumption at the cellular level, reflecting the high energy demand of the stress response. The results indicated that E. andrei can regulate internal Zn concentrations efficiently, regardless of form or concentration, without considerable impact on energy reserves or respiration rate.Electronic supplementary materialThe online version of this article (10.1007/s11356-019-05753-3) contains supplementary material, which is available to authorized users.

Maize Iranian mosaic virus infection promotes the energy sources of its insect vector, Laodelphax striatellus

AbstractMaize Iranian mosaic virus (MIMV, family Rhabdoviridae) causes an important disease in cereal crops in Iran. It is transmitted by the planthopper Laodelphax striatellus in a persistent, propagative manner. In the present study, the effect of MIMV on the energy reserves of L. striatellus was studied by comparing energy contents in viruliferous and non‐viruliferous insects. Results showed that MIMV‐infected male and female adults, and nymphs stored 1.82, 2.24 and 1.7‐fold more total energy reserves than non‐viruliferous individuals. This is consistent with a 2.55‐fold increase of the total energy (sum of energy sources in nymphs and adults) of viruliferous compared to non‐viruliferous specimens. A significant increase in glycogen (2.26‐fold), carbohydrate (2.13‐fold), lipid (1.63‐fold) and protein (1.96‐fold) was documented in viruliferous insects compared to non‐viruliferous insects. Based on these results, we conclude that MIMV enhances the energy reserves of its vector and therefore, may play a vital role in the ecology of L. striatellus.

Development of a body condition score for the mountain chicken frog (Leptodactylus fallax).

The Critically Endangered mountain chicken frog (Leptodactylus fallax) has undergone drastic population decline due to habitat loss, hunting, invasive species, and chytridiomycosis. In response, several partner institutions initiated a conservation breeding program. It is important to maintain the captive population in good health. Therefore the program partners have recommended establishment of protocols for health examination of the species, including body condition assessment. Visual body condition scoring is a useful means to assess body condition in zoo animals for which regular bodyweight measurements are impractical or associated with capture-related stress. In this study, the authors developed a visual body condition score for the mountain chicken frog based on an ordinal categorical scale from 1 to 5 (1 = lowest body condition, 5 = highest body condition) using anatomical features that vary with total body energy reserves. Veterinary staff, animal managers, keepers, researchers, and students subsequently used the body condition score to assign scores to 98 mountain chicken frogs (41 male, 57 female) aged between 8 months and 12 years housed in five zoos in the UK and Jersey between February and March 2016. Body condition scores showed moderate (rho = 0.54; males) to strong (rho = 0.6; females) correlation with the scaled mass index, an objective measure of total energy reserves. The majority of pairwise comparisons between scores showed slight to substantial intra-observer agreement (93.8%) and slight to almost perfect inter-observer agreement (97.2%). Cases of poor agreement were likely due to limited observer experience working with the species.

Coral physiology and microbiome dynamics under combined warming and ocean acidification.

Rising seawater temperature and ocean acidification threaten the survival of coral reefs. The relationship between coral physiology and its microbiome may reveal why some corals are more resilient to these global change conditions. Here, we conducted the first experiment to simultaneously investigate changes in the coral microbiome and coral physiology in response to the dual stress of elevated seawater temperature and ocean acidification expected by the end of this century. Two species of corals, Acropora millepora containing the thermally sensitive endosymbiont C21a and Turbinaria reniformis containing the thermally tolerant endosymbiont Symbiodinium trenchi, were exposed to control (26.5°C and pCO2 of 364 μatm) and treatment (29.0°C and pCO2 of 750 μatm) conditions for 24 days, after which we measured the microbial community composition. These microbial findings were interpreted within the context of previously published physiological measurements from the exact same corals in this study (calcification, organic carbon flux, ratio of photosynthesis to respiration, photosystem II maximal efficiency, total lipids, soluble animal protein, soluble animal carbohydrates, soluble algal protein, soluble algal carbohydrate, biomass, endosymbiotic algal density, and chlorophyll a). Overall, dually stressed A. millepora had reduced microbial diversity, experienced large changes in microbial community composition, and experienced dramatic physiological declines in calcification, photosystem II maximal efficiency, and algal carbohydrates. In contrast, the dually stressed coral T. reniformis experienced a stable and more diverse microbiome community with minimal physiological decline, coupled with very high total energy reserves and particulate organic carbon release rates. Thus, the microbiome changed and microbial diversity decreased in the physiologically sensitive coral with the thermally sensitive endosymbiotic algae but not in the physiologically tolerant coral with the thermally tolerant endosymbiont. Our results confirm recent findings that temperature-stress tolerant corals have a more stable microbiome, and demonstrate for the first time that this is also the case under the dual stresses of ocean warming and acidification. We propose that coral with a stable microbiome are also more physiologically resilient and thus more likely to persist in the future, and shape the coral species diversity of future reef ecosystems.

Estimation of Influence of Explosive Characteristics of Emulsion Explosives on Shotpile Width

The article deals with the question of the effect of explosive characteristics of emulsion explosives on the shotpile width. Currently, there are two main points of view to select an efficient type of explosive, which contributes to the qualitative destruction (fragmentation) of coarse clastic rocks. The first is based on the assumption that the detonation velocity of explosives must correspond to the break-down point of the rock (dynamic compression). Another point of view is that the detonation pressure of explosives determines only the head part of the pulse, on which the rock fragmentation is dependent only near the charge, in the contact zone around the borehole. The fragmentation of the entire rock volume within a given borehole array depends on the total magnitude of the explosion pulse, determined not by the detonation velocity, but by the total energy reserve of the explosive charge. Experimental explosions with some of the most common industrial explosives have been carried out in the current conditions of blasting of borehole charges by various types of industrial explosives from the point of view to select the most important parameter, which determines its influence on the shotpile width The investigations have been carried out according to the data obtained to establish that the energy properties of explosives (heat of explosive transformation and density of explosives) determine the decisive influence on the shotpile width, and the operability, the volume of the released gases, the detonation velocity for the change in the shotpile width have very little effect and may not be taken into account in calculations for the prediction of the shotpile.

Physiological and Biogeochemical Responses of Super-Corals to Thermal Stress from the Northern Gulf of Aqaba, Red Sea

Mass coral bleaching is increasing in frequency and severity, leading to the loss of coral abundance and diversity. However, some corals are less susceptible to bleaching than others and can provide a model for identifying the physiological and biogeochemical traits that underlie coral resilience to thermal stress. Corals from Eilat in the Gulf of Aqaba in the northern Red Sea do not bleach unless seawater temperatures are sustained at +6⁰C or higher above their average summer maximum. This extreme thermal tolerance qualifies these as super-corals, as most corals bleach when exposed to temperatures that are only +1-2⁰C above their thermal maximum. Here, we conducted a controlled bleaching experiment (+6°C) for 37 days (equivalent to 32-degree heating weeks) on three species of corals from Eilat: Stylophora pistillata, Pocillopora damicornis, and Favia favus. To assess the response of the holobiont to thermal stress, the following variables were measured on each coral: endosymbiotic algal cell density, Chlorophyll a, endosymbiotic mitotic cell division, total lipids, protein, carbohydrate, and the stable carbon (d13C) and oxygen (d18O) isotopic composition of the skeleton and the d13C of the animal host tissue and endosymbiotic algae. While all three species appeared visibly bleached, their physiological and biogeochemical responses were species-specific. S. pistillata catabolized lipids but still maintained total energy reserves and biomass. Increases in both skeletal d13C and d18O indicates that calcification declined in this species. P. damicornis was the least affected by bleaching. It maintained its total energy reserves and biomass, and isotopic evidence suggests that it maintained calcification and was not dependent on heterotrophy for meeting metabolic demand when bleached. Finally, F. favus catabolized protein and carbohydrates, and suffered losses in total energy reserves and biomass. Nevertheless, isotopic evidence suggest that photosynthesis and calcification were maintained, and that this species has a high baseline heterotrophic capacity. Thus, just like their non-super-coral counterparts, maintaining energy reserves and biomass, and heterotrophic capacity appear to be traits that underlie the thermal tolerance of these super-corals from Eilat. Given the high thermal tolerance of these super-corals, these populations could provide viable seed stock for repopulating coral losses on other reefs.

Short Communication: HIV Patient Systemic Mitochondrial Respiration Improves with Exercise.

In HIV-infected individuals, impaired mitochondrial function may contribute to cardiometabolic disease as well as to fatigue and frailty. Aerobic exercise improves total body energy reserves; however, its impact at the cellular level is unknown. We assessed alterations in cellular bioenergetics in peripheral blood mononuclear cells (PBMC) before and after a 12-week aerobic exercise study in sedentary HIV-infected subjects on stable antiretroviral therapy who successfully completed a 12-week aerobic exercise program. In this prospective study, participants underwent supervised 20-40 min of light aerobic exercise (walking or jogging) performed three times per week for 12 weeks, gradually increasing to maintain an intensity of 50%-80% of heart rate reserve. Maximal aerobic capacity (VO2MAX) was assessed by a graded exercise test on a cycle ergometer before and after completion of the study. PBMC from compliant subjects (attended at least 70% of exercise sessions) were assessed for mitochondrial respiration using the Seahorse XF24 Bio-Analyzer. Seven of 24 enrolled subjects were compliant with the exercise regimen. In these individuals, a significant increase (p = .04) in VO2MAX over 12 weeks was found with a median increase of 14%. During the same interval, a 2.45-fold increase in PBMC mitochondrial respiratory capacity (p = .04), a 5.65-fold increase in spare respiratory capacity (p = .01), and a 3.15-fold (p = .04) increase in nonmitochondrial respiration was observed. Aerobic exercise improves respiration at the cellular level. The diagnostic and prognostic value of such improved cellular respiration in the setting of chronic HIV warrants further investigation.

DMS-Based Energy Optimizations for Clustered WSNs

In this article, we consider clustered wireless sensor networks where the nodes harvest energy from the environment. We target performance-sensitive applications that have to collectively send their information to a cluster head by a predefined deadline. The nodes are equipped with Dynamic Modulation Scaling (DMS)-capable wireless radios. DMS provides a tuning knob, allowing us to trade off communication latency with energy consumption. We consider two optimization objectives, maximizing total energy reserves and maximizing the minimum energy level across all nodes. For both objectives, we show that optimal solutions can be obtained by solving Mixed Integer Linear Programming problems. We also develop several fast heuristics that are shown to provide approximate solutions experimentally.