Increase In Frequency Research Articles

Effects of Wildfires on Soil Organic Carbon in Boreal Permafrost Regions: A Review

ABSTRACTWildfire strongly influences permafrost environment and soil organic carbon (SOC) pool. In this study, we reviewed the effects of fire severity, time after a fire, and frequency on SOC in boreal permafrost regions. This review highlighted several key points: the effect of wildfires on SOC increased with an increase of fire severity, and the amount of vegetation returned and surface organic matter replenished was less in a short term, which resulted in a significantly lower SOC content compared to that of before the fire. Within a short period after fire, the SOC in near‐surface permafrost and the active layer decreased significantly due to the loss of above ground biomass, permafrost thaw, and increased microbial decomposition; as the years pass after a fire, the SOC gradually accumulates due to the contributions of litter layer accumulation and rooting systems from different stages of succession. The increase in fire frequency accelerated permafrost thawing and the formation of thermokarst, resulting in the rapid release of a large amount of soil carbon and reduced SOC storage. Therefore, the study on the effects of wildfires on SOC in the boreal permafrost region is of great significance to understanding and quantifying the carbon balance of the ecosystem.

Can blue–green infrastructure counteract the effects of climate change on combined sewer overflows? Study of a swiss catchment

Abstract Combined sewer overflows (CSOs), the discharge of untreated sewage mixed with stormwater into surface waters, are expected to increase under climate change as a result of more extreme rainfall. Blue–green infrastructure (BGI), such as bioretention cells and porous pavements, can help to reduce the amount of stormwater entering combined sewer systems, thus reducing CSO discharge. However, our understanding of the potential for BGI to mitigate CSOs in a future climate is still lacking, as performance is typically evaluated for individual BGI elements with fixed implementation areas under historical climate conditions or limited future scenarios. In response, this study investigates the performance of 30 combinations of BGI elements and implementation rates to prevent increases in CSOs under a range of future climate scenarios in an urban catchment near Zurich, Switzerland. Median total annual rainfall, projected to increase by as much as 46%, could double the median annual CSO volume and increase median annual CSO frequency by up to 52%. Four BGI combinations that include bioretention cells show the most promise to prevent increases in CSO volume and frequency in a future climate; and given the diverse responses of BGI elements to distinct rainfall patterns, their combinations can enhance CSO discharge reduction across varying climate patterns. BGI is also likely to become more cost-effective under future climatic conditions as projected increases in total rainfall led to larger CSO volume reductions obtained through BGI. However, there is a trade-off between robustness to climate change and cost-effectiveness, since CSO volume reduction capacity scales with BGI implementation rate but cost-effectiveness declines. Our study illustrates the effectiveness of various BGI combinations to prevent increases in CSOs in a future climate, calling for a range of BGI elements and implementation areas to be considered for urban drainage adaptation.

The effect of multi-field coupling on dynamic recrystallization behavior in IN718 alloy

The dynamic recrystallization behavior of IN718 alloy is studied under multi-field coupling based on deformation difficulty at high temperature. The results show that dynamic recrystallization of IN718 alloy occur at 750°C under multi-field. At the same temperature, the resistance of IN718 alloy decreases and the degree of dynamic recrystallization increases with the increase of pulse current frequency. The dynamic recrystallization mechanism of alloy under multi-field coupling is discontinuous mechanism of grain boundary arch nucleation. The dynamic recrystallization ability is significantly improved under the action of multi-field coupling, thus the deformation resistance is reduced. The reason is that the dislocation movement intensifies under the action of multi-field coupling, which promotes dislocation proliferation and recovery, and then promotes dynamic recrystallization.

Ad Hoc Adaptations to Climate Change in Coastal Communities

Climate change disproportionately impacts coastal residents in the United States. Existing studies document institutional efforts to adapt to sea level rise through projects like seawalls, beach nourishment, and property acquisitions to protect communities from rising seas. Such studies capture institutional adaptations, but do not include ad hoc adaptations by homeowners impacted by climate change. How are homeowners adapting to climate hazards? This paper analyzes ethnographic and interview data from 100 households in two coastal counties in North Carolina, a state with one of the most climate vulnerable shorelines in the country. This analysis of homeowner response considers ad hoc adaptations along the North Carolina coast. Results show that homeowners recognize climate hazards and regularly adapt on their own within the context of institutionally maintained flood protection infrastructure and transportation access to the places where they live. Residents are aware of and attempt to access support for home adaptations when programs or funds are available to them after disasters and do so with varying levels of success, though the more pervasive adaptations to chronic stress are not supported by government programs or insurance mechanisms. Ad hoc adaptations may provide short-term protection from climate hazards but have questionable long-term efficacy as sea levels rise and storm strength and frequency increases. Leaving communities and households to adapt on their own as chronic climate hazards outpace institutional response exacerbates existing inequalities by relying on residents with different levels of resources and agency to adapt.

Ih Block Reveals Separation of Timescales in Pyloric Rhythm Response to Temperature Changes in Cancer borealis.

Motor systems operate over a range of frequencies and relative timing (phase). We studied the contribution of the hyperpolarization-activated inward current (Ih) to frequency and phase in the pyloric rhythm of the stomatogastric ganglion (STG) of the crab, Cancer borealis as temperature was altered from 11°C to 21°C. Under control conditions, the frequency of the rhythm increased monotonically with temperature, while the phases of the pyloric dilator (PD), lateral pyloric (LP), and pyloric (PY) neurons remained constant. When we blocked Ih with cesium (Cs+) PD offset, LP onset, and LP offset were all phase advanced in Cs+ at 11°C, and the latter two further advanced as temperature increased. In Cs+ the steady state increase in pyloric frequency with temperature diminished and the Q10 of the pyloric frequency dropped from ~1.75 to ~1.35. Unexpectedly in Cs+, the frequency displayed non-monotonic dynamics during temperature transitions; the frequency initially dropped as temperature increased, then rose once temperature stabilized, creating a characteristic "jag". Interestingly, these jags were still present during temperature transitions in Cs+ when the pacemaker was isolated by picrotoxin, although the temperature-induced change in frequency recovered to control levels. Overall, these data suggest that Ih plays an important role in the ability of this circuit to produce smooth transitory responses and persistent frequency increases by different mechanisms during temperature fluctuations.

Perceptibility and Pain Thresholds in Low- and High-Frequency Alternating Current Stimulation: Implications for tACS and tTIS

AbstractTranscranial electrical stimulation (tES) has emerged as a promising tool for neuromodulation, but its application is often limited by the discomfort associated with higher stimulation intensities. Newer variants like transcranial temporal interference stimulation (tTIS) utilize high-frequency alternating currents (≥ 500 Hz) to penetrate deeper brain regions while mitigating perceptual discomfort. This study sought to examine sensation and pain thresholds across various stimulation frequencies of alternating currents, aiming to explore the boundaries of comfortable intensities. Additionally, we sought to evaluate the efficacy of an anesthetizing topical cream in increasing participant comfort and potentially extending the range of tolerable stimulation levels. We recruited 37 participants and applied alternating current stimulation to the head at various frequencies (10 Hz, 20 Hz, 500 Hz, 1000 Hz, and 2000 Hz) to determine intensity-dependent perception and pain thresholds. Additionally, thresholds were determined under the influence of a topical anesthetic. Our findings confirm that as stimulation frequency increases, perceptibility decreases, with higher frequencies allowing a manyfold increase in stimulation intensity before becoming perceptible or causing pain. Additionally, the anesthetizing cream was efficacious in further reducing perceptibility and pain sensations across all frequencies. This study lays the groundwork for future research by establishing comfortable limits for stimulation intensities, particularly in the context of high-frequency stimulation. The reduced perceptibility of high-frequency stimulation, coupled with the effectiveness of anesthetizing creams, enables the administration of higher stimulation intensities for more potent neuromodulatory interventions without causing discomfort.

Mechanocatalytic Hydrogenolysis of the Lignin Model Dimer Benzyl Phenyl Ether over Supported Palladium Catalysts.

This work demonstrates the mechanocatalytic hydrogenolysis of the ether bond in the lignin model compound benzyl phenyl ether (BPE) and hardwood lignin isolated by hydrolysis with supercritical water. Pd catalysts with 4 wt % loading on Al2O3 and SiO2 supports achieve 100% conversion of BPE with a toluene production rate of (2.6-2.9) × 10-5 mol·min-1. The formation of palladium hydrides under H2 gas flow contributes to an increase in the turnover frequency by a factor of up to 300 compared to Ni on silica-alumina. While a near-quantitative toluene yield is obtained, some of the phenolic products remain adsorbed on the catalyst.

Frequency Dependence of the Parameters of the Inductive RF Discharge Located in the Low-Value Magnetic Field

In this work, we carried out studies of the properties of an inductive RF discharge placed in a magnetic field with an induction of less than 70 G at frequencies of 2, 4 and 13.56 MHz. Experiments have shown that when operating at frequencies of 2 and 4 MHz at low powers of the RF generator, the range of existence of the discharge is limited by large magnetic fields. The efficiency of RF power input η non-monotonically depends on the magnitude of the magnetic field. The position of the main maximum η shifts to the region of higher B with increasing frequency, power of the RF generator and argon pressure, and at the same time the maximum broadens. An increase in frequency, power and argon pressure is accompanied by an increase in the absolute values of η. When operating at a frequency of 4 MHz, in addition to the main maximum η, a local maximum appears in the region B 35–70 G. With increasing pressure, a shift in the position of the local maximum and its smoothing is observed. Comparison of experimental data with calculated data allows us to conclude that the local maximum of plasma density observed at weak magnetic fields is associated with resonant excitation of waves in the plasma source. At a frequency of 2 MHz, the excited wave is close to a transverse helicon, and at a frequency of 13.56 MHz, its properties approach the Trivelpiece–Gold wave.

Exploring intra-urban thermal stress vulnerability within 15-minute city concept: Example of heat waves 2021 in Moscow

Heat vulnerability in big cities is important because of the increase in heat wave frequency and thermal stress that is identified by Urban Heat Island. Our study investigated intra-urban heat vulnerability in Moscow, which strongly influenced by historic context in urban planning, with a focus on local disparities. We considered the vulnerability framework in terms of “exposure,” “sensitivity,” and “adaptive capacity,” and adopted the concept of a 15-minute city to evaluate spatial patterns on example of 2021 heat waves. We used high-resolution meteorological data from the regional meteorological model COSMOCLM and calculated the Physiologically Equivalent Temperature (PET) to assess thermal stress and define exposure. The data from OSM and other open sources were used to assess sensitivity and adaptive capacity through the proximity of green spaces, cooling centers, healthcare, and premium service facilities. The PET varied from 25.3 °C in the outskirts to 30.2 °C in Moscow centre; however, variations in thermal stress did not have adverse effects on the spatial patterns of vulnerability. The vulnerability indicator in the east was six times higher than in more prosperous areas of the center, north and southwest, due to historical development, mainly the transformation from former industrial areas into residential areas.

Dynamic Simulation Model and Performance Optimization of a Pressurized Pulsed Water Jet Device

Pulsed water jet technology has broad application prospects in the field of rock breaking. The pressurized pulsed water jet (PPWJ) is a new type of pulsed jet that offers high-amplitude pressurization, variable pulse pressure and frequency, and a high energy usage rate. To achieve a more destructive and powerful pulsed water jet, a dynamic simulation model of the device was established by using the AMESim software (v1400) based on the operational principle of PPWJs, and the simulation model was validated against the experimental results. The relationships between the key structural parameters of the PPWJ device and the pulse parameters were quantitatively investigated. The pulse pressure and frequency can be increased by appropriately increasing the nozzle diameter or boost ratio, and the pulse pressure will drop if the nozzle diameter or boost ratio exceeds a threshold value. Increasing the maximum displacement or action area of the piston will increase pulse length while decreasing pulse frequency; a proper match of the maximum displacement or action area of the piston will assure pulse peak pressure. The maximum outer diameter of the piston only affects the pulse frequency. The key structural parameters of the device were optimized on that foundation. Compared to the original device, the optimized device resulted in an increase in pulse frequency and jet output energy, leading to larger diameter and volume of erosion pits at the same stand-off distance and erosion time. The findings of this study offer valuable scientific insights for achieving efficient rock breaking with PPWJ.

Trait-based Anxiety Symptoms are Associated with Higher Incidence of Nightmare Frequency in the Wisconsin Sleep Cohort

ABSTRACT Objectives Nightmares affect up to 12% of the population and are often comorbid with psychiatric disorders like anxiety and depression. Limited research has examined their influence on nightmare frequency. This study investigates the relationship between depression and trait-anxiety symptoms on incident nightmare frequency at follow-up. Method Cross-sectional and longitudinal analyses were conducted on 758 Wisconsin Sleep Cohort participants. Trait anxiety and depression symptom severity were measured using the State Trait Anxiety Inventory and Zung Depression Scale. Ordinal regression determined nightmare frequency cutoffs based on anxiety and depression severity. Cross-sectional associations were assessed with Spearman and Kruskal–Wallis tests. Longitudinal associations were analyzed using adjusted binomial regression of binary nightmare frequency (low: <4/month, high: >5/month) against clinical cutoffs of trait anxiety and depression. Results Adjusted models indicated a small correlation between baseline nightmare frequency and trait anxiety (β = 0.01, p = .010) and depression symptoms (β = 0.01, p = .005). High baseline trait-anxiety symptoms were associated with frequent nightmares at follow-up (OR = 3.75, CI95% [1.306,10.793], p < .014), but depression symptoms were not (OR = 1.35, CI95%[0.399, 4.587], p = .627). Conclusions Our findings suggest that high trait-anxiety symptoms are associated with increased incident nightmare frequency, when adjusted for depression. However, high depression symptoms were not associated with an increase in nightmare frequency when adjusted for trait-anxiety.

Abstract Mo074: Overexpression of IPP2 Impairs Intracellular Calcium Handling, Leading to Arrhythmogenic Events

Cardiac arrhythmias, which are disruptions in the heart's electrical activities, critically affect the ventricular conduction system, impairing efficient blood circulation. These disturbances result in irregular heartbeats, contributing to patient mortality or causing harm to distant organs via embolic events. Given the severe implications, a profound understanding of the molecular mechanisms driving arrhythmia is crucial for devising specific treatments. This study unveils a pioneering link between the overexpression of IPP2 (Protein Phosphatase 1 Regulatory Inhibitor Subunit 2), driven by the Myh6 promoter (termed TgIPP2), and the onset of age-dependent cardiac arrhythmias. The electrical abnormalities observed in TgIPP2 overexpressing mice include a spectrum of dysfunctions such as axis deviations, elongated QRS and PR intervals, absence of P waves, AV dissociation, ventricular tachyarrhythmia, and heightened T waves. Investigating the pathophysiology behind these electrical anomalies, we subjected young adult mice to catecholamine challenges at low doses and conducted surface electrocardiogram (EKG) monitoring. TgIPP2 mice demonstrated a notable increase in arrhythmogenic episode frequency and duration following 0.2 mg/kg isoproterenol injection compared to their control counterparts. Through a protein phosphorylation analysis, we identified a key regulator of the ryanodine receptor, which modulates calcium release from the sarcoplasmic reticulum, correlating with the extended PR intervals and the delayed peaking of T waves. Therapeutic trials employing RyR blockers, specifically dantrolene, successfully normalized the erratic cardiac rhythms in aged TgIPP2 mice. However, beta blockers or L-type calcium channel blockers induced sudden cardiac death in this model. The study reveals that IPP2-induced aberrant phosphorylation disrupts calcium homeostasis, leading to arrhythmias. In conclusion, our research marks a significant advancement in understanding arrhythmogenic mechanisms, demonstrating that IPP2 overexpression directly triggers arrhythmia, particularly affecting the atrioventricular (AV) node, atria, and ventricles. The discovery that aberrant phosphorylation, especially of the RyR regulator, plays a pivotal role in initiating cardiac arrhythmias opens new pathways for targeted anti-arrhythmic therapies.

Maintenance of response to ketogenic diet therapy for drug-resistant epilepsy post diet discontinuation: A multi-centre case note review

PurposeThere is limited research on the proportion of individuals with epilepsy who maintain response to ketogenic diet therapy (KDT) after discontinuing treatment. We aimed to determine the proportion of individuals who did / did not maintain response post KDT and explore factors that may influence the likelihood of maintaining response. MethodsRetrospective data were collected from 97 individuals from 9 KDT centres. Individuals had achieved ≥50 % seizure reduction on KDT for at least 12 months, with seizure frequency data available at 3 months+ post diet. Outcome 1 was: recurrence of seizures or increase in seizure frequency post diet; outcome 2: recurrence of seizures, increase in seizure frequency or an additional anti-seizure treatment started post diet. Results61/97 (62.9 %) individuals maintained response at latest follow-up (mean 2.5[2.0] years since stopping KDT). Approximately one third maintained response without further anti-seizure treatments. One quarter of individuals had an increase in frequency or recurrence of seizures within 6 months (95 %CI 4, 12) for outcome 1 and within 3 months (3, 6) for outcome 2.Individuals who did not achieve seizure freedom on diet were significantly more likely to have an increase in seizures or to require additional anti-seizure treatments post diet compared to those who were seizure-free on diet (hazard ratio 4.02, 95 %CI (1.46, 11.16) p < 0.01). ConclusionOur findings should help guide clinical teams with the information they provide patients and their families regarding likelihood of long-term seizure response to KDT. Realistic costings for KDT services may need to be considered.

Coccolithophore Assemblage Response to Indian Monsoon–ENSO Teleconnections During the Last Century

AbstractWe present a new, annually resolved coccolithophore relative abundance record (1889–1993 CE) from a laminated marine sediment core obtained from the northeastern Arabian Sea to document assemblage variations during the last century. Our analysis revealed that ∼80% of the assemblage is composed of the coccolithophore species Gephyrocapsa oceanica, Emiliania huxleyi, and Florisphaera profunda. Hierarchical clustering of the coccolithophore data delineates time intervals (1889–1909 CE, 1910–1959 CE, 1960–1993 CE) comparable to previously reported interdecadal changes of the El Niño–Southern Oscillation (ENSO)–Indian monsoon variance. We find that F. profunda (Fp%) is positively correlated with central Pacific ENSO (Niño 4 and Niño 3.4). Frequency analyses of Fp% match ENSO quasiperiodicity reported from instrumental data and proxy records and support the existence of previously described ENSO–Indian monsoon teleconnections. Furthermore, the increased variance of Fp% and associated decrease in marine primary productivity starting ∼1960 CE appears to be driven by decreased upward nutrient transport linked to increased surface water stratification due to surface ocean warming. With the predicted increases in frequency and strength of central Pacific El Niño as well as surface ocean warming and upper ocean stratification in the Indian Ocean over the coming century, our results imply further impacts on coccolithophores in the northeastern Arabian Sea that may have cascading effects on the marine food web and global biogeochemical cycles.

Enhancing flood mapping through ensemble machine learning in the Gamasyab watershed, Western Iran.

Floods are among the natural hazards that have seen a rapid increase in frequency in recent decades. The damage caused by floods, including human and financial losses, poses a serious threat to human life. This study evaluates two machine learning (ML) techniques for flood susceptibility mapping (FSM) in the Gamasyab watershed in Iran. We utilized random forest (RF), support vector machine (SVM), ensemble models, and a geographic information system (GIS) to predict FSM. The application of these models involved 10 effective factors in flooding, as well as 82 flood locations integrated into the GIS. The SVM and RF models were trained and tested, followed by the implementation of resampling techniques (RT) using bootstrap and subsampling methods in three repetitions. The results highlighted the importance of elevation, slope, and precipitation as primary factors influencing flood occurrence. Additionally, the ensemble model outperformed both the RF and SVM models, achieving an area under the curve (AUC) of 0.9, a correlation coefficient (COR) of 0.79, a true skill statistic (TSS) of 0.83, and a standard deviation (SD) of 0.71 in the test phase. The tested models were adapted to available input data to map the FSM across the study watershed. These findings underscore the potential of integrating an ensemble model with GIS as an effective tool for flood susceptibility mapping.

Ten-year statewide cross-sectional review of pediatric sinogenic intracranial abscess and empyema in Queensland, Australia: microbial profile before and after COVID-19.

Sinogenic intracranial infections in children, such as subdural empyema or intracranial abscess, are a rare disease process with significant associated morbidity. Recent literature has suggested that there may have been an increase in frequency of these infections following the COVID-19 pandemic, but the literature has been conflicting, perhaps related to the heterogenous management of COVID-19 lockdowns in various states and differences in data capture between methods. The collection of statewide Australian data overcomes these limitations by capturing a comprehensive sample though the public healthcare system of patients who were subject to a homogeneous statewide approach to public health policy during the COVID-19 pandemic (population 5.6 million, including 1.3 million children). The objective of this study was to present population-level data to address the question of whether the incidence of intracranial infections changed in pediatric patients before and after the COVID-19 pandemic. The authors present a retrospective 10-year statewide description of sinogenic intracranial infections in Queensland, Australia. A comparison was made between the incidence and microbiological profile before and after the onset of COVID-19 lockdowns on March 22, 2020. Forty-four pediatric intracranial infections undergoing neurosurgical intervention were identified within the review period. After exclusion of postsurgical and cardioembolic causes, 33 sinogenic intracranial infections were included (16 before and 17 after 2020, with a mean annualized incidence of 0.25 vs 0.37 cases per 100,000 children, respectively; p > 0.05). The most frequent organisms identified were Streptococcus milleri (n = 19), polymicrobial (n = 4), and S. aureus (n = 3). No significant differences in antimicrobial profile, susceptibility, parenchymal involvement, or clinical outcome were identified between the pre- and post-COVID-19 groups. No statistically significant differences in the epidemiology of pediatric intracranial infection have occurred in the state of Queensland, Australia, before and after March 22, 2020, and the COVID-19 pandemic.

Synergistic patient factors are driving recent increased pediatric urgent care demand.

We aimed to use the high fidelity urgent care patient data to model the factors that have led to the increased demand at our local pediatric urgent care centre. The dataset for this retrospective cohort study was obtained from our local healthcare centre's national reporting data for pediatric urgent care visits from 2006 to 2022. Variables analyzed included: basic patient demographics, chief complaint, triage urgency, date and time of registration/discharge, discharge diagnosis, and discharge destination. Statistical analysis of non-linear trends was summarized by locally estimated scatterplot smoothing splines. For machine learning, we used the tidymodels R package. Models were validated in training using k-fold cross validation with k = 5. We used univariate linear regression as a baseline model. After the data was standardized, correlation and homoscedasticity were evaluated between all parameter permutations. This dataset consisted of 164,660 unique visits to our academic centre's pediatric urgent care. Over the study period, there was an overall substantial increase in the number of urgent care visits per day, with a rapid increase beyond previous levels in 2021 and further in 2022. The increased length of stay trend was consistent across presenting complaint categories. The proportion of patients without primary care in 2022 was 2.5 times higher than in 2013. A random forest machine learning model revealed the relative importance of features to predicting a visit in 2022 were: longer stay, later registration in the day, diagnosis of an infectious illness, and younger age. This study identified a combination of declining primary care access, circulating viral infections, and shifting chief complaints as factors driving the recent increase in frequency and duration of visits to our urgent care service.

Model test on the effects of shield machine cutterhead vibration on tunnel face stability in sandy ground

Face stability is one of the essential problems in shield tunneling. When tunneling in cobble stratum or mixed face ground conditions, significant cutting-induced cutterhead vibration would occur and affect the face stability. To reveal the mechanism and effect of vibration on the tunnel face stability, a transparent tunnel model with a movable vibration exciter was designed and a series of model tests were performed under different vibration magnitudes Aa and frequencies f. Meanwhile, particle image velocimetry was used to reveal the displacement field and the failure pattern of the tunnel face. The test results indicate that the cutting-induced vibration produces a significant reduction effect on the tunnel face stability, as expressed by the increase of the face support pressure and the failure zone when the vibration magnitude and frequency increase. Compared with the static unloading conditions, the width of the failure wedge Lwt increased by about 5.75% and 35.66% for the loose and dense sand, respectively, under dynamic unloading conditions (Aa = 0.2 g, f = 10 Hz). The limit support pressure increased up to about 0.20γD at a vibration of 0.3 g and 50 Hz, much larger than those of static conditions, which were about 0.08γD–0.09γD. An observable self-stabilizing arch can be formed in dense sand under static unloading conditions, while under dynamic unloading conditions, the long-time stable soil arch would not occur. The contributions of this paper could provide an insightful understanding of the effects of cutterhead vibration on tunnel face stability.

Characterization of underwater manipulator based on the fluid-structure interaction under pulsating flow

Abstract Underwater manipulators are taking on an increasingly significant function in marine biological fishing operations. Under the action of the ocean flow field, vortex-induced vibration will be induced, which will cause fatigue damage or even fracture of the underwater manipulator. Based on the Ansys fluid-solid coupling software, this paper simulates the vortex-induced vibration response characterizations of underwater manipulators under pulsating flow conditions. The pulsation flow at the entrance is realized by changing the velocity amplitude and pulsation frequency. The influence laws of pulsating frequency and amplitude on the CL , CD, and wake vortex shedding are investigated. The results showed that the CL and CD of the underwater manipulator increased by 133.33 % and 39.18 %, respectively, with an increase in the pulsation parameter. Additionally, with the increase of pulsating frequency, the banded vortex behind the underwater manipulator is gradually obvious, and the energy in the vortex is also increasing.

The heat is on: reduced detection of floral scents after heatwaves in bumblebees.

Global climate change disrupts key ecological processes and biotic interactions. The recent increase in heatwave frequency and severity prompts the evaluation of physiological processes that ensure the maintenance of vital ecosystem services such as pollination. We used experimental heatwaves to determine how high temperatures affect the bumblebees' ability to detect floral scents. Heatwaves induced strong reductions in antennal responses to floral scents in both tested bumblebee species (Bombus terrestris and Bombus pascuorum). These reductions were generally stronger in workers than in males. Bumblebees showed no consistent pattern of recovery 24 h after heat events. Our results suggest that the projected increased frequency and severity of heatwaves may jeopardize bumblebee-mediated pollination services by disrupting the chemical communication between plants and pollinators. The reduced chemosensitivity can decrease the bumblebees' abilities to locate food sources and lead to declines in colonies and populations.