Search Results (2,995)

The aim of this study was to elucidate the reproductive strategy of Camellia luteoflora, an endangered evergreen endemic to karst ecosystems. We observed and recorded its flowering phenology and flower-visiting insects, observed pollen morphology, determined pollen viability, and assessed stigma receptivity. The results showed that the flowering period of C. luteoflora started from early September to late December, with the average flowering period of individual flowers being 10–12 days. The pollen morphology of C. luteoflora was subprolate and prolate, with three germinal apertures and the fossulate exine ornamentation. Pollen viability was the highest at the initial opening stage (80.30%). In the process of pollen in vitro, the order of influence on the germination rate and pollen tube length was temperature > sucrose > calcium chloride (CaCl₂) > boric acid (H₃BO₃). The best combination for the germination rate was 24 °C, 75 g/L sucrose, 0.2 g/L CaCl₂, 0.15 g/L H₃BO₃, while that for the pollen tube length was 24 °C, 100 g/L sucrose, 0.2 g/L CaCl₂, 0.25 g/L H₃BO₃. Stigma receptivity was the strongest at the full blooming stage. The pollen/ovule ratio (P/O) was 2240, suggesting a facultative outcrossing breeding system. The outcrossing index (OCI) was 4, suggesting that the exogamous breeding system is the cross-pollination type, partially self-compatible and insect pollinator-dependent. The flower-visiting insects included bees, weevils, and ants. In summary, C. luteoflora exhibits an extended flowering period, with a prolonged overlap of stable pollen viability and stigma receptivity, suggesting a potential strategy to cope with pollination uncertainty. However, field observations recorded only a few species of potential pollinators, while the occurrence frequency of non-pollinating insects was relatively high. It is thus hypothesized that this apparent lack of effective pollinators may act as a potential barrier to successful fertilization and natural regeneration, which might also be one of the factors contributing to its endangered status. Future studies, particularly pollinator exclusion and hand-pollination experiments, are critically needed to verify whether pollinator limitation is indeed a key factor. Full article

The oxygen depletion in worldwide oceans and inland waters is becoming an increasingly prevalent problem. Here, two comparative study sites, Baltic Proper (BP) and Shuikou Reservoir (SR), were selected to identify the dynamics of dissolved oxygen (DO) and the related physicochemical response by conducting five field investigations over a one-year period. The DO concentrations were 0–9.9 mg L⁻¹ and 0.3–8.7 mg L⁻¹ in BP and SR, with average oxygen change rates of −0.016~0.014 mg L⁻¹ d⁻¹ and −0.022~0.018 mg L⁻¹ d⁻¹, respectively. Such oxygen dynamics were highly related to salinity, temperature, turbidity, and chlorophyll-a than nitrogen and phosphorus. The persistent hypoxia (i.e., DO < 2 mg L⁻¹) emerged below 63 m in BP during all sampling months where the reversal points of Brunt–Väisälä frequency N expressed in the form log₁₀[N² (s⁻²)] were −4. The seasonal hypoxia covered the downstream of SR at depths below 11.5 m in September with the highest log₁₀[N² (s⁻²)] between −3.95 and −3.64. The log₁₀[N² (s⁻²)] ≈ −4 may indicate the occurrence and development of hypoxia in both regions. In the case of the persistent and seasonal hypoxic conditions in BP and SR, the impact of temperature and turbidity on DO was opposite. Low oxygen levels in SR occurred under elevated temperature and turbidity. Additionally, under hypoxic conditions in both regions, NO₃⁻ and NH₄⁺ concentrations significantly depended on DO changes. This study contributes to the understanding of seasonal changes in oxygen dynamics in different water bodies, and highlights different oxygen conditions and physicochemical responses to the oxygen changes. Full article

Wetlands are an important part of coastal ecosystems but are under increasing pressure from climate change-induced sea-level rise and flooding, in addition to development pressures associated with increasing human populations. The change in tidal events and their intensity due to sea-level rise is also reshaping and challenging the vitality of existing wetland systems, requiring more intensive localized studies to identify future-focused restoration and conservation strategies. To support this endeavor, this study utilizes tide gauge datasets from the Australian Bureau of Meteorology (BOM) for maximum sea-level (Hmax) prediction and Landsat Collection surface reflectance datasets obtained from the United States Geological Survey (USGS) database to detect and project patterns of change in the Maroochy River floodplain of Queensland, Australia. This study developed an efficient hybrid deep learning model combining a Convolutional Neural Network and Bidirectional Long Short-Term Memory (CNNBiLSTM) architecture for the prediction of maximum sea-level and tidal events. The proposed model significantly outperformed three benchmark models (Multiple Linear Regression (MLR), Support Vector Regression (SVR), and CatBoost) in achieving a high correlation coefficient (r = 0.9748) for maximum sea-level prediction. To further address the increasing frequency and intensity of tidal events linked to sea-level rise, a CNNBiLSTM classification model was also developed, achieving 96.72% accuracy in predicting extreme tidal occurrences. This study identified a significant positive linear increase in sea-level rise of 0.016 m/year between 2014 and 2024. Wetland change detection using Landsat imagery along the Maroochy River floodplain also identified a substantial vegetation loss of 395.64 hectares from 2009 to 2023. These findings highlight the strong potential of integrating deep learning and remote sensing for improved prediction and assessment of sea-level extremes and coastal ecosystem changes. The study outcomes provide valuable insights for informing not only conservation and restoration activities but also for providing localized projections of future change necessary for the progression of effective climate adaptation and mitigation strategies. Full article

This study updates the climatology of lake-effect (LE) snowfall over Lake Champlain by analyzing radar and surface data from nine winter seasons spanning 2015 to 2024. A filtering approach was applied to isolate periods with favorable LE conditions, and events were manually classified using criteria consistent with a previous climatology from 1997 to 2006. A total of 64 LE events were identified and compared across the two periods to evaluate potential changes associated with regional warming. Despite a substantial reduction in lake ice cover during the recent decades, no increase in LE frequency or duration was observed. Instead, warming has shifted the seasonal distribution of events, with fewer early-season cases and more late-season occurrences. LE events also exhibited shorter durations and higher minimum temperatures and dew points. These findings suggest that warming may constrain LE snowfall development over small lakes such as Champlain, in contrast to intensification trends reported for larger lake systems. The analysis also highlights a rarely documented transitional band type that migrated along the lake axis during synoptic shifts. Results underscore the value of observational climatologies for detecting emerging snowfall behaviors in response to climate variability. Full article

In this paper, the natural frequencies of pure bending, axial–bending, and torsional-bending coupled modes of CFRP Anisogrid cylindrical shell-beams supporting non-structural masses and inertias at the boundaries are firstly analytically investigated and, secondly, verified by FEM. Indeed, the design of shell-beam elements in various engineering applications is driven by the minimum frequency value that is necessary to achieve in order not to compromise the proper functionality of the assembly for which these elements are designed. In turn, this minimum frequency depends on the geometry, mass, and dynamics of the main components of the assembly. A typical point in space applications is to control the lowest frequency of the spacecraft body, commonly supported by a shell structure, in order to avoid the occurrence of resonance issues that may be induced by dynamic loads during the launch phase. As a rule, to keep the lowest frequency sufficiently high, in conjunction with non-structural masses, means to increase the stiffness and the mass of the load-carrying structure and, ideally, to identify the most efficient solution. In order to effectively address this topic, the analytical models of the natural frequencies of Anisogrid cylindrical shell-beams are finally introduced into an optimization routine as constraints on the fundamental frequency. This approach allows us to readily explore the various Anisogrid configurations and find the best candidate solutions in the framework of preliminary design. Full article

Lead contamination remains a critical global concern due to its persistent toxicity, bioaccumulative nature, and widespread occurrence in water, food, and industrial environments. The accurate, cost-effective, and rapid detection of lead ions (Pb²⁺) is essential for protecting public health and ensuring environmental safety. Among the available techniques, potentiometric sensors, particularly ion-selective electrodes (ISEs), have emerged as practical tools owing to their simplicity, portability, low power requirements, and high selectivity. This review summarizes recent progress in lead-selective potentiometry, with an emphasis on electrode architectures and material innovations that enhance analytical performance. Reported sensors achieve detection limits as low as 10⁻¹⁰ M, broad linear ranges typically spanning 10⁻¹⁰–10⁻² M, and near-Nernstian sensitivities of ~28–31 mV per decade. Many designs also demonstrate reproducible responses in complex matrices. Comparative analysis highlights advances in traditional liquid-contact electrodes and modern solid-contact designs modified with nanomaterials, ionic liquids, and conducting polymers. Current challenges—including long-term stability, calibration frequency, and selectivity against competing metal ions—are discussed, and future directions for more sensitive, selective, and user-friendly Pb²⁺ sensors are outlined. Full article

Very little is known about goose-beaked whales (Ziphius cavirostris) and Sowerby’s beaked whales (Mesoplodon bidens), especially off the western coast of Ireland, due to their elusive behaviors. This study aimed to characterize the acoustics of these beaked whales and investigate whether temporal patterns may affect their occurrences. Using passive acoustic monitoring (PAM), beaked whale bioacoustic clicks were manually analyzed, revealing different click frequency ranges than expected. Double clicks and echoes produced by both beaked whale species were also present, which have previously been infrequently observed in these species. The occurrence of beaked whales and the presence of double clicks and echoes were further investigated, along with how the diel cycle may affect these click characteristics. Hourly presence of goose-beaked whale double clicks and echoes was found to have significance for both day and night. There was no significance found for Sowerby’s beaked whale double clicks and echoes for day and night, along with the hourly occurrences of both beaked whales and the occurrence of other beaked whales. These findings highlight the need for future research on PAM and beaked whale acoustics, which could aid in better monitoring of their presence to address the impacts of human activities. Full article

The phenomenon of surface freezing in lakes, rivers, and reservoirs, has been an essential part of Poland’s winter landscape for centuries. It plays critical ecological roles, such as regulating heat balance and influencing the state of biocenoses. Due to progressive climate warming, we have observed significant changes in ice cover duration, thickness, and timing in recent decades. Ice phenomena on rivers are temporary. They strongly depend on air temperature, which has recently been increasing worldwide. This paper analyzes the variability of ice phenomena formation in selected river profiles of the central Vistula River catchment, central Poland. The research period covers the years 1968–2016. The data come from the Institute of Meteorology and Water Management-State Research Institute (IMGW-PIB). The duration (including the dates of occurrence and disappearance of the phenomenon) and the frequency of occurrence of ice phenomena over the long-term were determined with particular attention to ice cover. The long-term occurrence of ice phenomena shows a decreasing trend (shorter duration, later onset dates) with a simultaneous increase in the average air temperature during the winter half of the hydrological year. Full article

The objective of this study was to evaluate the temporal trend of suicide deaths and the disparities in the occurrence of suicide death between Indigenous and non-Indigenous populations. This ecological study analyzed deaths from intentionally self-inflicted injuries in the southern region of Brazil (states of Paraná, Santa Catarina, and Rio Grande do Sul) from 2010 to 2019. The variables analyzed included annual frequency of events, age, sex, marital status, and education level. Descriptive analysis, association measures, and verification of temporal trends were performed. The average age-standardized suicide mortality rate for both populations was approximately 9.0 per 100,000 inhabitants, with a predominance among males (80%), single individuals (65%), and youth (37%). When only the state of Paraná was considered, the mortality rate during the period was 12.41 among the Indigenous population versus 6.94 per 100,000 inhabitants in the non-Indigenous population. In this state, the probability of suicide death was found to be almost twice as high among Indigenous men and women, with 13 times greater odds of death among Indigenous children and youth. A statistically significant temporal increase in the number of cases was observed only in the non-Indigenous population. An annual seasonal pattern of events among Indigenous individuals was suggested. The findings indicate a high suicide rate among the Indigenous population, particularly in Paraná, especially among young, single individuals, with a growing trend over the years. Full article

This study presents a comprehensive statistical analysis of ionospheric midnight collapse events over Arecibo, based on incoherent scatter radar (ISR) observations collected between 1971 and 2019. A total of 224 nights with valid measurements were examined to characterize the timing, intensity, and seasonal variation of these collapse events. The results showed that midnight collapses occurred on 94.6% of the nights, with the highest occurrence rate observed during spring and winter. The first collapse typically began between 22:00 and 00:00 LT, lasted for 1–4 h, initiated at altitudes between 350 and 400 km, and involved a vertical collapse of 50–100 km. A second collapse was identified on 18.8% of nights, occurring predominantly between 01:00 and 02:00 LT, with a notably higher frequency during winter. Compared to the first collapse, the second collapse tended to originate at lower altitudes and exhibited faster collapse rates. Seasonal patterns in the vertical ion drift ($V_z$) were also identified, with winter events characterized by a persistently downward $V_z$ throughout the night. Further decomposition of $V_z$ into field-aligned ($V_{ap}$) and perpendicular ($V_{pn}$) components indicated that $V_{ap}$ played a dominant role in modulating $V_z$, particularly on nights with double collapses. Analysis of meridional wind variations revealed that nighttime changes in $V_{ap}$ were largely controlled by meridional wind, suggesting a strong coupling between thermospheric wind dynamics and field-aligned ion motion. These findings suggest that variations in $V_z$, primarily driven by meridional-wind-controlled changes in $V_{ap}$, are a key driver of ionospheric midnight collapse events at Arecibo. Full article

Spacecraft and satellites are equipped with cryogenic storage systems to maintain instruments and engines at optimal operating temperatures. However, in cryogenic storage tanks, the steep temperature gradient along the pipeline (arising from sections inside and outside the tank) may induce instability in stored gases such as helium or hydrogen, leading to large-amplitude, self-excited thermoacoustic oscillations, known as Taconis oscillations. Taconis oscillations not only cause structural damage to pipelines, jeopardizing the safety of the cryogenic storage system, but also produce significant heat leakage and boil-off losses of cryogens. This study employs computational fluid dynamics (CFD) to simulate Taconis oscillations within a U-shaped cryogenic helium pipeline. The flow dynamics and acoustic field characteristics of the cryogenic helium pipeline are first analyzed. Fast Fourier transform and wavelet transform are employed to characterize the Taconis oscillations. A subsequent parametric study investigates the influence of the location and magnitude of temperature gradients on the dynamic behavior of Taconis oscillations. Simulation results reveal that the onset temperature gradient is at a minimum when the temperature gradient is applied at one-quarter of the cryogenic pipeline. To prevent the occurrence of Taconis oscillations, the transition between the warm and cold sections should be away from one-quarter of the cryogenic helium pipe. Moreover, increasing the temperature gradient leads to the emergence of multiple oscillation modes and an upward shift in their natural frequencies. This research gives deeper insights into the dynamics of thermally induced thermoacoustic oscillations in cryogenic pipelines, providing guidelines for improving the efficiency and safety of cryogenic storage systems in aerospace engineering. Full article

Energy raw materials are the basis of the economic system. From this emerges the need to examine in more detail how various uncertainty indices interact with the dynamic of spillover connectedness among energy markets. The TVP-VAR model is used to investigate connectedness among US, European, and Indian oil and gas markets and the S&P carbon allowances Eua index. Following this, the wavelet decomposition technique is used to capture the dynamic correlations between uncertainty indices (GPR and VIX) and connectedness indices. First, the results indicate that energy market spillovers are time-varying and crisis-sensitive. Second, the time–frequency dependence among uncertainty indices and connectedness indices is more marked and can change with the occurrence of unexpected events and geopolitical conflicts. The VIX index shows a positive dependence on total dynamic connectedness in the mid-long-term, while the GPR index has a long-term effect only after 2020. The analysis of the interdependence among the connectedness of each market and the uncertainty indices is more heterogeneous. Political tensions and geopolitical risks are, therefore, causal factors of energy prices. Given their strategic and economic importance, policy makers and investors should establish a risk warning mechanism and try to avoid the transmission of spillovers as much as possible. Full article

Background/Objectives. Heart rate variability (HRV) is the variability in the beat-by-beat heart period. Primary focal hyperhidrosis (PFHH) is a disease characterized by excessive sweat production, strongly affecting social life. Several authors define this condition as a dysautonomic disorder, mainly driven by exaggerated sympathetic activity. The aim of the study was to demonstrate a possible cardiac involvement in the disease. Other outcomes were the occurrence of dysautonomic disorders after surgery and its possible correlation with baseline characteristics. Methods. This observational, controlled trial enrolled patients with a confirmed clinical diagnosis of severe PFHH candidates to thoracoscopic sympathetic chain clamping. Before and after surgery, ECG was obtained using KardiaMobile 6L (AliveCor^®, Mountain View, CA, USA) device with a five-minute recording and HRV was analyzed using Kubios HRV Premium (Kubios©) software. Results. 111 patients were compared to 222 healthy control subjects. No differences were seen in HRV analysis between the two groups at baseline (time-domain p > 0.05, frequency-domain p > 0.05, autonomic indexes p > 0.05). When comparing autonomic function indexes in patients before and after the surgical procedure, no differences were seen in frequency-domain HRV analysis, but a blunted increase in SNS index (0.2 vs. 1.38, p 0.02). No development of systemic dysautonomic disorders nor significant compensatory hyperhidrosis were seen after the surgery. Conclusions. This study shows that PFHH is a peripheral autonomic nervous system derangement, rather than central. Sympathetic chain clamping resulted safe and effective in improving patients’ conditions, with no risks of dysautonomic disorders. Full article

The aim of this study is to provide a systematic account of structural discourse markers operating at a conversational macro-level in German Palliative Care interactions, focusing on their frequency, distribution, co-occurrence, and speaker-group-specific usage. By combining qualitative approaches from conversation analysis and interactional linguistics with quantitative methods from corpus linguistics, discourse markers are analyzed together as a functional category from multiple analytical perspectives to enhance the overall understanding of the use of discourse markers. The analysis reveals a functional distribution across different transition points in conversation: Whereas the German so most frequently appears in openings and transitions to non-verbal activities, gut and okay predominate in topic shifts and conversation closings. However, gut and okay differ in their composition of discursive functions, although discourse structuring emerges as the second most frequent function in both cases, an observation that stands in contrast to the continued neglect of this function in standard dictionary entries. The institutional asymmetries inherent in medical interactions are reflected in the finding that both doctors and caregivers use significantly more structural discourse markers than patients and their relatives. Differences between physicians’ and caregivers’ use of discourse markers can be attributed to their different professional roles and communicative responsibilities. Full article

China’s media governance policies play a crucial role in shaping media ecology and promoting the modernization of national governance capacity. This study employed the Latent Dirichlet Allocation (LDA) model and co-occurrence network analysis to systematically analyze the thematic content of national-level media governance policies issued in China between 1996 and 2024, and to examine the evolution of policy themes from a triple logical synergy perspective. In consideration of the socio-economic context and governance issues, this study has categorized the evolution of media governance policies into four distinct phases. This study used the LDA model to extract high-frequency words and built a co-occurrence network to explore the structural relationship among these words, with a synergy framework to analyze the thematic evolution across periods. The findings indicate that China’s media governance policies over the past three decades have been the result of stage-by-stage adjustments under the synergistic influences of technological drivers, social demands, and governance philosophies. Media governance constitutes a pivotal component in the modernization of China’s national governance capacity. A comprehensive analysis of the evolution of policy themes reveals the internal pattern of media governance in China. Full article