Temperature Disturbance Research Articles

Potential distribution of three invasive agricultural pests in China under climate change

Invasive pests reduce biodiversity and ecosystem service functions, thereby leading to economic and also agricultural losses. Banana skipper (Erionota torus Evans), red palm weevil (Rhynchophorus ferrugineus), and coconut caterpillar (Opisina arenosella Walker) are invasive insect pests in the palm-growing regions and they have had serious consequences for the planting of bananas (Musa nana), palms (Trachycarpus fortune) and coconut (Cocos nucifera). Based on screened occurrence data, the present research utilized Maximum Entropy model (Maxent) to simulate the distribution dynamics of these three invasive insects in China, under current and future climate (2050s, 2070s, 2090s) in two shared socio-economic pathways (SSPs: 126 and 585) of the newly released coupled model intercomparison project phase6 (CMIP6). The results show that: (1) Under current and future climate conditions, all model groups exhibited an AUC value exceeding 0.92, which shows that the model prediction results are very good;(2) The suitable habitat area of E. torus Evans remains relatively stable with some expansion in the SSP126 of 2090s and some contraction in the SSP585 of 2090s. The suitable habitat area of R. ferrugineus showed an overall contraction, with substantial contraction in the SSP585 of 2090s.The suitable habitat area of O. arenosella has an overall expansion, with the most pronounced expansion in the SSP585 of 2070s; (3) The current centroid of suitable habitats for R. ferrugineus and E. torus Evans is located in Guangxi Province and wholely shift toward the south direction under future climate. The centroid of suitable habitats for O. arenosella is currently located in the northeastern maritime area of Hainan Province and will shift toward the north direction under future climate; (4) Temperature, precipitation and Human disturbance factors (Population density and Human influence index) were crucial variables for describing the distribution of the three species. For E. torus Evans in particular, percentage contributions of Population density was up to 31.4, which is only 0.1 different from ranked first Bio19 (Precipitation of the coldest quarter). The dynamics of habitats of these three species and the correlating driver factors proposed in this work provide essential insights into future spatial management of the three invasive insects in China. Our work is necessary and timely in identifying newly areas at high risk of expansion of the three invasive insects in the future, then suggesting strategic control measures to prevent their spread, and finally providing scientific evidence for the early prevention and rapid response to the three invasive insects.

Thermal-noise-limited ultra-stable laser operated at 698 nm

Ultra-stable lasers are indispensable in high precision measurements. Here we demonstrate an ultra-stable laser system that reaches the thermal noise limit of the optical cavity for the 698 nm clock transition laser of strontium atomic optical clock. This is achieved by locking the frequency of the external-cavity diode laser (ECDL) to a full ULE optical cavity with a length of 10 cm. By suppressing noise such as temperature disturbance, vibration, residual amplitude modulation (RAM), and fiber phase noise, the measured laser linewidth is less than 0.9 Hz. After subtracting the linear drift of 60 mHz/s, the frequency instability of the beat signal reaches 1.2 × 10−15 at 1 s averaging time, which is close to the thermal noise limit of the optical cavity.

Richtmyer-Meshkov instability when a shock wave encounters with a premixed flame from the burned gas

We present a linear stability analysis of the Richtmyer-Meshkov instability that develops when a shock wave reaches a sinusoidally perturbed premixed flame from behind. In the hydrodynamic regime, when acoustic contributions dominate the flame growth rate, the problem is analytically addressed by the direct integration of the sound wave equations at both sides of the flame, which are bounded by the reflected and transmitted shock waves and the flame front that acts as a contact surface in the hydrodynamic limit. The resolution involves: a hyperbolic change of variables to modify the triangular spatio-temporal domain, a transformation in the Laplace variable, the resolution of the functional equations in the frequency domain, and the final inverse Laplace transform. The latter involves a novel resolution method that is proven beneficial for long-time dynamics. Asymptotic analysis is also carried out to describe the early time and late time hydrodynamic response. The nonuniform flow field resulting from distorted oscillating shocks is characterized by acoustic, rotational, and entropic disturbances, each of which exerts a substantial influence on flame dynamics. These disturbances contribute to the intricate interplay of factors shaping the behavior of the flame in response to the nonuniform flow. In particular, the sensitivity of local flame propagation to temperature disturbances is investigated. This work contributes to a deeper understanding of Richtmyer-Meshkov instability dynamics and offers insights into instability reduction through the modulation of temperature disturbances generated by the transmitted shock.

Temperature and Composition Disturbances in the Southern Auroral Region of Jupiter Revealed by JWST/MIRI

AbstractJupiter's South Polar Region (SPR) was observed by James Webb Space Telescope/Mid‐Infrared Instrument in December 2022. We used the Medium Resolution Spectrometer mode to provide new information about Jupiter's South Polar stratosphere. The southern auroral region was visible and influenced the atmosphere in several ways: (a) In the interior of the southern auroral oval, we retrieved peak temperatures at two distinct pressure levels near 0.01 and 1 mbar, with warmer temperatures with respect to non‐auroral regions of 12 ± 2 K and 37 ± 4 K respectively. A cold polar vortex is centered at 65°S at 10 mbar. (b) We found that the homopause is elevated to km above the 1‐bar pressure level inside the auroral oval compared to km at neighboring latitudes and with an upper altitude of 350 km in regions not affected by auroral precipitation. (c) The retrieved abundance of C2H2 shows an increase within the auroral oval, and it exhibits high abundances throughout the polar region. The retrieved abundance of C2H6 increases toward the pole, without being localized in the auroral oval, in contrast with previous analysis (Sinclair et al., 2018, https://doi.org/10.1016/j.icarus.2017.09.016). We determined that the warming at 0.01 mbar and the elevated homopause might be caused by the flux of charged particles depositing their energy in the SPR. The 1‐mbar hotspot may arise from adiabatic heating resulting from auroral‐driven downwelling. The cold region at 10 mbar may be caused by radiative cooling by stratospheric aerosols. The differences in spatial distribution seem to indicate that the hydrocarbons analyzed are affected differently by auroral precipitation.

Associations between residential daytime indoor temperature and self-reported sleep disturbances in UK adults: A cross-sectional study

BackgroundIn the past few decades, research on the association between indoor temperature and sleep has primarily used laboratory rather than field data collected in epidemiological cohorts. MethodsSecondary data on 2493 individuals aged 43 years was obtained from the National Survey of Health and Development (NSHD). Logistic regression models were used to investigate the associations between temperatures (indoor at home, spot measurement when the nurses visited during the day; and outdoor, monthly average) and self-reported sleep disturbances, adjusting for socio-demographics, health variables, housing variables, and temperature-related variables. ResultsAssociations were found between daytime indoor temperature with difficulty initiating (OR: 0.95, 95%CI: 0.91–0.98) and maintaining sleep (OR: 0.96, 95%CI: 0.93–0.99). Compared with neutral indoor temperatures (17–28 °C), low indoor temperature (≤17 °C) was associated with difficulty initiating sleep (OR: 1.79, 95%CI: 1.21–2.65). Stratified analysis results across tertiles showed that associations with difficulty initiating (OR: 0.87, 95%CI: 0.77–0.99) and maintaining sleep (OR: 0.88, 95%CI: 0.79–0.98) were observed respectively in the lowest (≤20 °C) and highest tertile (≥23 °C) of indoor temperature. There was no association between outdoor temperature and self-reported sleep disturbances in this study. ConclusionIn this first UK-based epidemiology study investigating temperature and sleep, self-reported sleep disturbances were associated with residential daytime indoor temperatures. Low indoor temperature had significantly higher odds ratio for difficulty initiating sleep compared with the neutral indoor temperature. A warmer indoor environment might be more suitable for sleep maintenance than sleep initiation. Indoor temperature in this study was a superior indicator of sleep disturbances than outdoor temperature. Although these findings are based on a UK sample, they may be relevant to other high-income settings with similar housing stock and climatic conditions.

Idiosyncratic invasion trajectories of human bacterial pathogens facing temperature disturbances in soil microbial communities

Current knowledge about effects of disturbance on the fate of invaders in complex microbial ecosystems is still in its infancy. In order to investigate this issue, we compared the fate of Klebsiella pneumoniae (Kp) and Listeria monocytogenes (Lm) in soil microcosms. We then used environmental disturbances (freeze–thaw or heat cycles) to compare the fate of both invaders and manipulate soil microbial diversity. Population dynamics of the two pathogens was assessed over 50 days of invasion while microbial diversity was measured at times 0, 20 and 40 days. The outcome of invasion was strain-dependent and the response of the two invaders to disturbance differed. Resistance to Kp invasion was higher under the conditions where resident microbial diversity was the highest while a significant drop of diversity was linked to a higher persistence. In contrast, Lm faced stronger resistance to invasion in heat-treated microcosms where diversity was the lowest. Our results show that diversity is not a universal proxy of resistance to microbial invasion, indicating the need to properly assess other intrinsic properties of the invader, such as its metabolic repertoire, or the array of interactions between the invader and resident communities.

Optimization on the peroxide ratio control strategy of PEMFC system based on immune algorithm

The air supply system is an essential component of a proton exchange membrane fuel cell (PEMFC), and proper control of the oxygen stoichiometry ratio(λo2) is crucial to prevent oxygen starvation in the PEMFC while maintaining efficient and stable performance output. In response to the issues of poor dynamic performance and slow response in traditional λo2 control strategies, this study was conducted to establish a dynamic oxygen flow model of the PEMFC and proposed a λo2 control strategy based on an immune algorithm-fuzzy PID (IAFPID). The performance of the IAFPID control strategy in λo2 control was analyzed under different load requirements, simulated vehicle dynamic loads, and temperature disturbances. The results demonstrate that the IAFPID control strategy has advantages such as fast convergence speed, strong robustness, and good dynamic performance. The efficiency of achieving the optimal stoichiometry ratio for high power output in PEMFC under disturbances was nearly 50% higher with IAFPID control compared to traditional PID, Fuzzy-PID, Genetic Algorithm PID, and Immune Algorithm PID strategies. Furthermore, this method ensures a lower average error in maintaining stable λo2 under dynamic disturbances compared to the IAPID and PID control strategies, with reductions of 12.93% and 37.75%, respectively.

Multiple hydraulic fracture propagation simulation in deep shale gas reservoir considering thermal effects

Deep and ultra-deep shale gas will gradually become the focus of unconventional oil and gas resources in the petroleum industry. In the development of shallow shale reservoirs, the multi-cluster hydraulic fracturing of horizontal wells is the commonly applied technique to create a network of fractures and achieve reservoir stimulation. However, for deep shale reservoirs, the behavior of multiple hydraulic fracture propagation is affected by stress interference between fractures. On the other hand, it is also influenced by the temperature disturbances caused by the injection of low-temperature fracturing fluids into high-temperature formations and the resulting thermal effects. Currently, most research on multiple hydraulic fracture propagation in shale only considers the interaction between fluids and solids while neglecting thermal effects. Therefore, based on the displacement discontinuity method, finite volume method, and finite difference method, this study established a numerical model for the non-planar propagation of multi-cluster hydraulic fractures in deep shale, considering the thermal effects. And the model was validated through numerical solutions of the temperature field and double-fracture propagation. Moreover, the number of fracture clusters, pumping rate, and formation temperature were selected as influencing factors, and the differences in multiple hydraulic fracture propagation with and without considering thermal effects were analyzed. The results show that as the formation temperature increases, the thermal effects become more significant, leading to greater differences in the morphology of multi-cluster fractures. Moreover, the thermal effects are more significant when the formation temperature exceeds 90 °C. Additionally, appropriately reducing the number of fracture clusters or increasing the pumping rate can to some extent mitigate stress interference between fractures and promote uniform fracture propagation. The findings of this study contribute to understanding the influence of thermal effects on multiple hydraulic fracture propagation and provide theoretical basis for the efficient development of deep shale gas.

The macroscopic and microscopic fatigue failure mechanisms of high-temperature thermally-damaged granite under cyclic impact loading

The rock surrounding wells for developing geothermal energy are in an extreme environment with high temperature and long-term dynamic disturbance. To study the influences of different temperatures and dynamic disturbances on the damage, mechanical properties, and fatigue failure mechanism of rocks, a series of microscopic thermal damage analysis and dynamic cyclic impact tests were conducted on granite specimens treated at 25 ∼ 900 °C. Results show that after being thermally treated to different extents, granite specimens are weakened in terms of the dynamic strength and deformation resistance under cyclic impact loading. As the temperature rises, the number of impacts bearable by specimens before failure decreases accordingly. Under the joint action of temperature and strain rate, 450 °C is found to be the threshold temperature for the significant reduction of dynamic strength of the rock. Under action of temperature and strain rate, the proportion of dissipated energy gradually reduces with rising temperature. Moreover, the dynamic failure mode of rock specimens at high temperatures gradually changes from splitting failure to crushing failure, the fractal dimension gradually increases, and the cumulative dissipated energy density decreases. Finally, the deterioration degree of elastic modulus was adopted to describe the progressive damage evolution of thermally-treated granite under cyclic impact loading. Furthermore, the fracture morphologies of rock specimens after failure were analyzed from the microscopic perspective to reveal the macroscopic and microscopic fatigue failure mechanisms of the rock under the coupling of temperature and strain rate.

Study on Spontaneous Combustion Risk Areas in Narrow Coal Pillar-Utilized Deep Mining and Double-Pipe Liquid CO2 Injection Technology

ABSTRACT Coal spontaneous combustion (CSC) in goafs, one of the most serious disasters in coal mines, not only wastes resources and destroys the ecological environment, but also causes casualties. As global underground mining gradually shifts to the deep, this problem becomes increasingly prominent. Deep mining is operated in a complex mechanical environment characterized with high stress, high permeability, high temperature, and strong mining disturbance. To avoid stress concentration areas, narrow coal pillars are often utilized in roadway excavation along the goaf. However, narrow coal pillars are likely to fracture and lose stability during the mining process. Consequently, goaf areas of two adjacent working faces might connect, which promotes the CSC risk in the goaf. Most of the current researches are focused on CSC risk areas under shallow mining conditions and the CSC-gas coupling disasters, yet research on CSC risk areas in the goaf triggered by narrow coal pillars under deep mining conditions is rarely reported. Moreover, there is a lack of relevant means to prevent and extinguish fires. This study takes the narrow coal pillar-utilized 130,205 working face in Yangchangwan Coal Mine as the research object. First, the development of coal pillar fractures was simulated by adopting the discrete element method of PFC. Besides, on-site monitoring and FLUENT numerical simulation were conducted to identify CSC risk areas in the goaf of the narrow coal pillar-utilized working face. Finally, a double-pipe liquid CO2 injection technology was proposed for fire prevention and extinguishing. The following beneficial results were obtained. Affected by high stress in deep mining, the coal pillar collapses, which expands the range of the oxidation zone on the return side. Meanwhile, the adjacent goaf is also exposed to CSC risk. Double-pipe liquid CO2 injection can effectively reduce air leakage near the working face and suppress spontaneous combustion of residual coal by inerting the goaf. This study can provide guidance and reference for fire prevention and extinguishing in goafs under the condition of narrow coal pillar-utilized deep mining.

Pore scale numerical simulation of flow and heat transfer non-equilibrium in randomly packed bed

The complex pore structure of porous media in packed beds leads to randomness and non-uniformity of flow and heat transfer. In this paper, the pore-scale method is used to numerically study the flow and heat transfer in 3D randomly packed bed. The average value and root-mean-square (RMS) of variables are used to evaluate the non-equilibrium characteristics of temperature and velocity. The results demonstrate that the packed bed consistently exhibits non-equilibrium phenomena due to the influence of porous media structure. The peak of thermal non-equilibrium occurs at the location with the largest temperature difference between gas and solid phases, while the peak of flow non-equilibrium occurs after reaching maximum temperature. With increasing inlet velocity, there is an expansion in both local velocity and temperature disturbance range, leading to a wider non-equilibrium region. However, the trend of non-equilibrium between flow and heat transfer is different.

Economically optimal operation of recirculating aquaculture systems under uncertainty

This study presents a novel economical operation scheme for recirculating aquaculture systems (RASs). The proposed approach is comprised of a moving horizon estimator and an economic model predictive controller (EMPC), which, respectively, provide the necessary feedback for the EMPC and make economically optimal decisions for the RAS. The scheme is enabled by a mechanistic RAS model, which is coupled with an objective function that jointly optimizes the economics of aquatic biomass growth and utility expenditure. The proposed scheme is tested on a rainbow trout case study, whereby it is compared against the previous state-of-the-art control approach in aerator failure and temperature disturbance scenarios. In both test scenarios, EMPC scheme outperforms the previous state state-of-the-art controller in terms of process economics (up to 41% improvement) as well as shorter batch times (up to 22% shortening). Furthermore, the scheme is shown to be capable of estimating uncertain parameters with little error (generally in the order of 5%) and negligible effect on economic performance when compared to cases with full measurement access and no uncertainty. The proposed scheme provides a new and automated way to ensure RASs operate with maximal productivity, thus further incentivizing sustainability and the uptake of this technology.

Hydrogen inhibition performance of blueberry anthocyanin as a green-potent inhibitor in wet Al alloy dust collector systems

To solve the fire and explosion risks caused by hydrogen generation of Al alloy dust in wet dust collector systems, an attempt is made to use blueberry anthocyanin (B-ACN), as a non-toxic and environmentally friendly inhibitor for hydrogen generation of Al alloy dust. Hydrogen inhibition effect and mechanism are evaluated through hydrogen production experiments, hydrolysis kinetic models, surface characterization analysis, and adsorption model. The results show that B-ACN exhibited a potent hydrogen inhibition efficiency of 97.36% at 4.50 g/L concentration, and maintained a hydrogen inhibition stability higher than 94.21% under temperature disturbance. In addition, theoretical calculations and surface characterization were performed to investigate the inhibition mechanism of B-ACN. SEM-EDS and XRD confirmed that the surface of the hydrolysis products of Al alloy dust in B-ACN solution is smooth and complete, with almost no generation of hydroxides. FTIR indicated that B-ACN adsorbs on the dust surface through the O atom. XPS and adsorption model suggested that the surface adsorption of B-ACN on the Al alloy dust involves both physical and chemical processes and follows the Langmuir adsorption model. Therefore, a dense and complete B-ACN protective film formed on the surface of Al alloy as a physical barrier, blocking the reaction between Al3+ and water molecules. This research provides a cost-effective, sustainable natural plant extract inhibitor to solve the risk of hydrogen generation and explosion, thereby achieving inherently safer industrial production and environmental protection.

Increased power capture efficiency of large-scale wind turbines using model-free coordinated pitch, yaw, and torque control with wind direction estimation in diverse environmental conditions

Offshore large-scale wind turbine systems (LSWTS) face challenges in pitch and yaw management mainly due to unreliable wind direction measurements, delayed responses, and redundant yaw movements, reducing their optimal efficiency under various offshore renewable environmental conditions. To address this problem and increase power capture, this study introduces a model-free coordinated super-twisting pitch, yaw, and generator torque control for LSWTS under various wind speed and direction conditions. To achieve this, a dynamic model of the weather vane is first designed to accurately measure the wind directions under fluctuating wind speed and environmental conditions. At the same time, the onshore/offshore LSWTS weather vane model is formulated to operate under optimal conditions considering air density, temperature, humidity, and external disturbances. Then, super-twisting control based on an enhanced adaptive barrier function is proposed for the coordinated control operation of the pitch, yaw, and generator torque actuators for stable maximum power extraction of the offshore LSWTS. Finally, simulation and comparative studies are presented to signify the increased power capture ability of the proposed scheme for both a 4.8 MW benchmark and a 20 MW PMVG-based offshore LSWTS to verify robustness against wind gusts, direction changes, and model uncertainties.

Altitudinal pattern of Odonata diversity in Kabylia (Algeria): a contrasting pattern in lotic and lentic habitats

Environmental conditions change rapidly across altitude, shaping diversity and structure of communities. Because lotic and lentic communities are often distinct and experience different environmental and anthropogenic conditions, understanding whether the diversity of these communities changes similarly across altitude is fundamental to determine how biota responds to ecological gradients in a human-dominated landscape. In this study, we carried out a comparative analysis of the altitudinal pattern of the diversity of odonates in lotic and lentic ecosystems in Kabylia (north-central Algeria) across 16 sites (eight lotic and eight lentic sites). We estimated species richness, abundance, and Shannon index as well as three environmental factors (water temperature, pH, and human disturbance) in each site. We recorded a total of 33 species (10 Zygoptera and 23 Anisoptera) with 20 species in lotic sites and 28 species in lentic sites. We recorded a similar decreasing altitudinal pattern of water temperature and human influence, but no pattern in pH. Interestingly, species richness, abundance, and Shannon index increased with altitude in lotic sites, but showed a weak negative correlation in lentic sites. These contracting patterns could be due to the interplay of a geographic gradient in anthropogenic pressure and habitat-specific species sensitivity to anthropogenic stress.

Solar Wind Plasma Parameters in Relation with Good Quality Magnetic Cloud Related Geomagnetic Storms

We have analyzed magnetic cloud related geomagnetic storms detected during the period of solar cycle 23 and 24 with disturbances in solar wind plasma parameters. We have observed that all the MC related geomagnetic storms are accompanying with disturbances in solar wind plasma parameters. The magnitude of magnetic cloud related geomagnetic storms is soundly correlated with peak disturbances values of solar wind plasma parameters solar wind plasma velocity (SWPV), solar wind plasma density (SWPD), solar wind plasma temperature (SWPT), interplanetary magnetic fields (IMFB) and southward component of interplanetary magnetic fields (IMFBz). Large positive correlation with correlation coefficient 0.60 have found between magnitude of MC related GMS and peak value of related disturbances in IMFB and 0.67 between magnitude of MC related geomagnetic storms and peak value of associated disturbances in IMFBz. Additionally positive correlations with correlation coefficient 0.54 have been found between magnitude of MC related GMS and peak value of associated disturbances in solar wind plasma temperature ,0.40 between magnitude of MC related GMS and peak value of associated disturbances in solar wind plasma velocity, 0.27 between magnitude of MC related geomagnetic storms and peak value of disturbances in soar wind plasma density.

LRRK2 is involved in heat exposure-induced acute lung injury and alveolar type II epithelial cell dysfunction

Heat exposure induces excessive hyperthermia associated with systemic inflammatory response that leads to multiple organ dysfunction including acute lung injury. However, how heat impairs the lung remains elusive so far. We aimed to explore the underlying mechanism by focusing on leucine-rich repeat kinase 2 (LRRK2), which was associated with lung homeostasis. Both in vivo and in vitro models were induced by heat exposure. Firstly, heat exposure exerted core temperature (Tc) disturbance, pulmonary dysfunction, atelectasis, inflammation, impaired energy metabolism, and reduced surfactant proteins in the lung of mice. In addition, decreased LRRK2 expression and increased heat shock proteins (HSPs) 70 were observed with heat exposure in both the lung of mice and alveolar type II epithelial cells (AT2). Furthermore, LRRK2 inhibition aggravated heat exposure-initiated Tc dysregulation, injury in the lung and AT2 cells, and enhanced HSP70 expression. In conclusion, LRRK2 is involved in heat-induced acute lung injury and AT2 cell dysfunction.

Modeling the influence of climate on groundwater flow and heat regime in Brandenburg (Germany)

This study investigates the decades-long evolution of groundwater dynamics and thermal field in the North German Basin beneath Brandenburg (NE Germany) by coupling a distributed hydrologic model with a 3D groundwater model. We found that hydraulic gradients, acting as the main driver of the groundwater flow in the studied basin, are not exclusively influenced by present-day topographic gradients. Instead, structural dip and stratification of rock units and the presence of permeability contrasts and anisotropy are important co-players affecting the flow in deep seated saline aquifers at depths >500 m. In contrast, recharge variability and anthropogenic activities contribute to groundwater dynamics in the shallow (<500 m) freshwater Quaternary aquifers. Recharge fluxes, as derived from the hydrologic model and assigned to the parametrized regional groundwater model, reproduce magnitudes of recorded seasonal groundwater level changes. Nonetheless, observed instances of inter-annual fluctuations and a gradual decline of groundwater levels highlight the need to consider damping of the recharge signal and additional sinks, like pumping, in the model, in order to reconcile long-term groundwater level trends. Seasonal changes in near-surface groundwater temperature and the continuous warming due to conductive heat exchange with the atmosphere are locally enhanced by forced advection, especially in areas of high hydraulic gradients. The main factors controlling the depth of temperature disturbance include the magnitude of surface temperature variations, the subsurface permeability field, and the rate of recharge. Our results demonstrate the maximum depth extent and the response times of the groundwater system subjected to non-linear interactions between local geological variability and climate conditions.

High resolution and large measurement range voltage sensing based on an optoelectronic oscillator utilizing an unbalanced Mach-Zehnder interferometer.

A voltage sensor with high resolution and large measurement range based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The key component in the cavity to select the oscillating signal is a finite impulse response (FIR)-microwave photonic filter (MPF) which consists of a sinusoidal broadband optical signal, an unbalanced Mach-Zehnder interferometer (MZI), a section of dispersion compensating fiber, and a photodetector. The center frequency of the FIR-MPF is mainly determined by the free spectral range (FSR) of the FIR-MPF. In the lower arm of the MZI, a cylindrical piezoelectric ceramic (PZT) wrapped with a section of optical fiber acts as voltage sensing head. Due to the inverse piezoelectric effect of PZT, the variation of the voltage will cause radial deformation of the cylindrical PZT and then lead to the change of the FSR of the MZI, determining the shift of center frequency of FIR-MPF as well as the frequency of the oscillating signal of the OEO. Thus, by monitoring the shift of the oscillation frequency of the OEO using an electric spectrum analyzer or a digital signal processor, a high-speed interrogation and high-resolution voltage measurement can be realized. Additionally, in the proposed scheme, an infinite impulse response (IIR)-MPF consisting of a fiber ring resonator is cascaded with the FIR-MPF to ensure the single-mode oscillation of the OEO. The experimental results show that a total range of 1700 V voltage sensing from - 200 V to 1500 V is accomplished with the voltage sensitivity of 0.25 GHz/100 V and the resolution of 0.3 V. By adjusting the proportion of the length of single mode fiber between two branches of MZI, the impact of temperature can be greatly reduced. The proposed sensor offers advantages such as a large measurement range, high resolution, high-speed interrogation, and stability to temperature disturbances, making it highly suitable for sensing applications in smart grids.

Development of optic disc edema during 30 days of hypercapnic head-down tilt bed rest is associated with short sleep duration and blunted temperature amplitude.

Sleep and circadian temperature disturbances occur with spaceflight and may, in part, result from the chronically elevated carbon dioxide (CO2) levels on the international space station. Impaired sleep may contribute to decreased glymphatic clearance and, when combined with the chronic headward fluid shift during actual spaceflight or the spaceflight analog head-down tilt bed rest (HDTBR), may contribute to the development of optic disc edema. We determined if strict HDTBR combined with mildly elevated CO2 levels influenced sleep and core temperature and was associated with the development of optic disc edema. Healthy participants (5 females) aged 25-50 yr, underwent 30 days of strict 6° HDTBR with ambient Pco2 = 4 mmHg. Measures of sleep, 24-h core temperature, overnight transcutaneous CO2, and Frisén grade edema were made pre-HDTBR, on HDTBR days 4, 17, 28, and post-HDTBR days 4 and 10. During all HDTBR time points, sleep, core temperature, and overnight transcutaneous CO2 were not different than the pre-HDTBR measurements. However, independent of the HDTBR intervention, the odds ratios {mean [95% confidence interval (CI)]} for developing Frisén grade optic disc edema were statistically significant for each hour below the mean total sleep time (2.2 [1.1-4.4]) and stage 2 nonrapid eye movement (NREM) sleep (4.8 [1.3-18.6]), and above the mean for wake after sleep onset (3.6 [1.2-10.6]) and for each 0.1°C decrease in core temperature amplitude below the mean (4.0 [1.4-11.7]). These data suggest that optic disc edema occurring during HDTBR was more likely to occur in those with short sleep duration and/or blunted temperature amplitude.NEW & NOTEWORTHY We determined that sleep and 24-h core body temperature were unaltered by 30 days exposure to the spaceflight analog strict 6° head-down tilt bed rest (HDTBR) in a 0.5% CO2 environment. However, shorter sleep duration, greater wake after sleep onset, and lower core temperature amplitude present throughout the study were associated with the development of optic disc edema, a key finding of spaceflight-associated neuro-ocular syndrome.