Typical Variations Research Articles

Insights into ‘Srdelara’ Purse Seines: Landing Composition and Trophic Relationships in the Pelagic Food Web

This study analysed commercial ‘Srdelara’ purse seine landings in the Central Eastern Adriatic from November 2020 to March 2022. The observed commercial landings demonstrated typical seasonal variations, with a peak from September to November and the lowest landings recorded from spring to early summer. Sardines dominated the purse seine landings, comprising 97.9% of the total landing, followed by anchovies at 1.3%, with occasional by-catches or other species. Biological analysis involved collecting samples of eight pelagic fish species (sardine, anchovy, round sardinella, Atlantic bonito, Atlantic horse mackerel, Atlantic mackerel, chub mackerel and bogue) captured by the aforementioned fishing gear during the study period. The length frequency distributions of the investigated fish species were predominantly unimodal, with the exception of the Atlantic horse mackerel. Moreover, the length–weight relationships indicated isometric growth for each examined species. Stable isotope analysis revealed overlapping isotopic niches among the eight analysed fish species, with estimated mean trophic positions ranging from 3.0 to 4.7, indicating consumption of prey across approximately two trophic levels. The round sardinella and bogue had the smallest isotopic niche, while Atlantic mackerel had the widest one. This study highlights the need for further research to evaluate the observed overlap among pelagic species, particularly between small and medium-sized pelagic fish, as this interaction could significantly impact their biomass. Determining the extent of this overlap is crucial for improving management strategies and ensuring the sustainability of pelagic fish stocks in the Adriatic Sea.

PHYSICS PERSPECTIVES ON HUMAN LOCOMOTION: INVESTIGATING THE MECHANICS OF WALKING PATTERNS

This study investigated the gait metric differences between males and females aged 18 to 22. Our investigation revealed some significant changes in gait metrics between the two genders. Firstly, males exhibited greater leg and step lengths than females. Males exhibited wider strides, suggesting typical anthropometric variations. Except for BMI and cadence, males had more variation in practically every other gait metric, whereas females had more variability. There was a non-significant positive connection between BMI and gait metrics such as height, stride length, and step width, with BMI having a minor effect on those measures. Overall, both genders showed a distinct pattern of variability, revealing individual variances in gait analysis across the same genders. A direct correlation was observed between the Froude number and height, indicating that individuals with a higher Froude number exhibit a more dynamic and faster walking style. This phenomenon can be ascribed to the biomechanical superiority that taller individuals may possess, enabling them to generate longer strides and achieve higher speeds. A thorough study of walking speed and gait parameters revealed difficulty in finding the right balance between stability, efficiency, and speed in human movement. Understanding these connections will help people develop more efficient training programs, assistive technologies, and more efficient and safe walking in general.

Surface Plasmon Resonance Sensor with 2D Materials for Enhanced Refractive Index Detection of Chemical Pollutants in Seawater

This paper introduces a highly sensitive, graphene-based, multilayer surface plasmon resonance (SPR) refractive index sensor is designed for the detection of chemical pollutants in seawater. The sensor structure consists of multiple layers, specifically BK7 glass, Chromium (Cr), Copper (Cu), MXene, and Graphene. SPR sensors have gained significant attention in the field of real-time chemical sensing due to their label-free detection capabilities, high sensitivity, and excellent reproducibility. In this sensor design, the refractive index (RI) of the sensing region is altered by the interaction of chemical pollutants present in the seawater. These variations in RI directly affect the excitation of surface plasmon polaritons (SPPs) at the multilayer sensor interface. This interaction forms the basis for detecting chemical pollutants, as changes in RI modulate the sensor's optical response, which can be accurately measured. The performance of the proposed sensor is thoroughly evaluated using numerical simulations based on the Transfer Matrix Method (TMM). The simulations are carried out over a refractive index range of 1.329 to 1.433, covering the typical RI variations caused by chemical pollutants in seawater. The sensor demonstrated exceptional performance, achieving a maximum sensitivity of 186deg/RIU at an operational wavelength of 633nm. Additionally, the sensor is exhibited a high detection accuracy (DA) of 1.5deg⁻¹ and a figure of merit (FOM) of 205 RIU⁻¹, highlighting its ability to precisely distinguish small changes in refractive index. These results emphasize the potential of this graphene-based SPR sensor configuration for high-performance detection of chemical pollutants, making it an excellent candidate for environmental monitoring applications. Its robust design, combined with its high sensitivity and accuracy, positions it as a promising solution for addressing challenges in seawater pollution detection and monitoring.

Socio-Demographic Influences on Dietary Habits and Nutritional Awareness: A Case Study of Polish Biathlon Association National Team Members.

This study investigated the influence of sociodemographic factors on the dietary habits of athletes of the Polish Biathlon Association. Focusing on age, education, employment status, and gender, this research assesses food choices, meal preparation, and nutritional awareness within a structured sports environment. A cross-sectional survey of 54 athletes was conducted using a modified "Eating Habits of Poles" questionnaire to explore food selection, preparation methods, consumption patterns, and nutritional perspectives. This focus on biathletes emphasizes their distinct dietary needs, which arise from the demanding combination of endurance and precision in their sport, providing valuable insights for tailored dietary strategies to enhance their performance and overall health. The results indicate that age, education, and employment status significantly influence Polish biathletes' dietary habits and nutritional awareness. Older athletes (under 23 years) demonstrated significantly higher nutritional awareness regarding modern dietary trends (p = 0.015). In contrast, 50% of higher-education athletes were more engaged in meal planning and healthier food choices than those with elementary education (p = 0.031). Employment status also played a role; 70% of the athletes were students who exhibited more convenience-based food choices, whereas 30% were employed and maintained more structured eating patterns (p = 0.008). Minimal gender differences were found, with 50% of male and 50% of female athletes showing similar dietary habits, likely due to standardized nutrition programs provided to all athletes. This indicates a potential need for further research to determine whether professional dietary support can effectively address typical gender-related variations in food behavior and lead to improvements in dietary outcomes. This study highlights the importance of targeted nutrition education and professional support for optimizing the nutritional habits of professional athletes. This emphasizes that socio-demographic factors such as age, education, and employment status significantly shape these behaviors, underscoring the need for personalized nutritional strategies within athletic programs.

Incorporating Diurnal and Meter-Scale Variations of Ambient CO2 Concentrations in Development of Direct Air Capture Technologies.

To be implemented on climate-relevant scales, direct air capture of CO2 (DAC) will require large capital-intensive facilities and careful attention to cost minimization. In making decisions among potential sites for DAC facilities, all of the factors that will impact process cost and efficiency should be considered. In this paper we focus on a factor that has previously received little attention in the DAC community, namely variations in atmospheric conditions on hourly time scales and length scales of meters. We present data curated from extensive previous studies of biosphere-atmosphere fluxes with observations of CO2 concentration, temperature, and relative humidity (RH) with hourly resolution from many sites in North America. These include locations where typical diurnal variations in CO2 concentration during summer months exceeds 150 ppm. These variations are larger than the seasonal variations that exist between averaged CO2 concentrations in winter and summer, and they are highly correlated with diurnal variations in temperature and RH. Diurnal variations are dependent on the height above ground at which CO2 concentrations are measured, with smaller variations existing at heights of 10 m or more than at ground level. We illustrate the potential implications of these short-term variations for the operation and optimization of a DAC process with process-level calculations for a specific adsorption-based process using amine-rich adsorbents.

Seasonal variation and demographic characteristics of acute tonsillitis and peritonsillar abscess in ENT practices in Germany (2019-2023).

Peritonsillar abscess (PTA) is a common soft tissue infection of the head and neck. It remains unclear to what extent inflammatory diseases of the palatine tonsils or other infections contribute to the development of PTA. This study examines the demographic characteristics and seasonal variations of acute tonsillitis (aT) and PTA in ENT practices in Germany using a practice database. Retrospective analysis based on data from the German-wide IQVIA™ Disease Analyzer database for the period 2019 to 2023. Data include diagnoses of aT (ICD-10: J03) and PTA (ICD-10: J36) as well as patient demographics (age, sex). Seasonal variations were identified by analysing the monthly diagnosis rates. The Pearson correlation between the monthly case numbers of aT and PTA was determined. 59,934 cases of aT and 5,024 cases of PTA were recorded. The mean age was 30.3 years (aT) and 39.4 years (PTA). The proportion of female patients was 60% (aT) and 49% (PTA). Both diagnoses showed seasonal variations with peaks in winter and spring and a decline in summer, although the decline was less pronounced for PTA. The monthly case numbers of aT and PTA showed high correlations between r = 0.75 (2019) and r = 0.94 (2020). The average correlation for the period 2019-2023 was r = 0.81. During the coronavirus pandemic, a significant decrease in the case numbers of both diseases was observed, while the typical seasonal variations disappeared. After the pandemic, the case numbers increased to higher levels than before the pandemic. aT and PTA both show seasonal variations with peaks in winter and spring and a decline in summer. The correlation between the variations of aT and PTA could be related to a partly common aetiology or to the specific sample of the practice database. The attenuation of seasonal variation during the coronavirus pandemic illustrates the impact of COVID-19 on the incidence of other diseases and on the use of healthcare pathways by patients.

A Monograph on Anatomy and Variants of Hepatic Resectional Surgery

BACKGROUND: The liver anatomy appears to be very complex due to the enormous number of vascular and biliary branches as well as the fact that the underlying pathology frequently distorts the anatomy. To prevent damage during surgical or invasive procedures, it is advised to be aware of the arteries’ typical structure and variations. Hepatic surgeons, general surgeons, transplant surgeons, interventional radiologists, and other medical specialists who treat liver problems must have this knowledge. MATERIALS AND METHODS: We have retrospectively evaluated the PubMed databases, Embase, and the Cochrane Library by applying various combinations of subject-related terms. The search terms identified with the medical subject heading were “Anatomy, right hepatectomy, resection, variants.” The databases were used to collect the literature published since 1991. RESULTS: Results delineated that 91.6% of patients had a single right hepatic vein, 81% shared a trunk with their middle hepatic vein (MHV) and left hepatic vein (LHV), and 19% had separate MHV and LHV drainage into the inferior vena cava. Overall prevalences of the abnormal hepatic artery, abnormal right hepatic artery (aRHA), abnormal left hepatic artery (aLHA), and combined aRHA/aLHA were found to be 27.41%, 15.63%, 16.32%, and 4.53%, respectively. The most common variation (type 2) is the so-called “portal vein (PV) trifurcation,” in which the main PV divides into the left PV, the right anterior PV, and the right posterior PV. The right posterior sectoral duct joins the left hepatic duct with a supraportal course, the right posterior sectoral duct joins the right anterior sectoral duct with an infraportal course, the trifurcation variation of the biliary tree, retroportal course, and the left lateral segmental ducts caudal to the umbilical portion of the PV are examples of variant biliary anatomy encountered in PV variations. Duplication of the common bile duct is a very uncommon congenital biliary system defect. CONCLUSION: It is very crucial for surgeon to have abreast knowledge of the tributaries, their anatomy, and variations to limit blood loss and operative morbidities.

High-Resolution WRF Modeling of Wind and Thermal Regimes with LCZ in Almaty, Kazakhstan

This study evaluates the effectiveness of the Weather Research and Forecasting (WRF) model in simulating high-resolution atmospheric conditions for Almaty, Kazakhstan, a city prone to stagnant winter air. While the previously used Bougeault and Lacarrere scheme for parameterizing the planetary boundary layer was applied in high-resolution modeling, the number of vertical levels was increased, and a detailed local climate zones (LCZs) map was included. Ground-based observations from meteorological stations and monitoring stations, remote sensing data, and radiosonde measurements are used to verify the model. Comparison results with ground-based observations show that the WRF model with the LCZ map provides a better representation of the wind and thermal regimes of Almaty compared to the three-class land use map, including in high resolution. A good correspondence of wind direction is demonstrated by comparing the modeling results with pollutant transport plumes recorded by remote sensing data. In addition, a good correlation was found between land surface temperature from satellite data and air temperature simulated by WRF with a resolution of 333 m. A comparison of simulated data and aerological measurements confirmed that downscaling did not have a significant impact on boundary layer calculations. Analysis of turbulent processes showed that the adopted model effectively describes the attenuation and dissipation of turbulent kinetic energy and reflects the typical diurnal variations of meteorological processes in the atmosphere of Almaty in the anticyclonic winter period. The results of high-resolution WRF modeling can form the basis for the development of a hybrid system capable of modeling atmospheric processes at the building level.

Regional Classification of Courtyard Houses across Maharashtra

Sensitivity to the regional context and an inductive approach is essential to realise the intentions behind the Maharashtrian traditional house forms. This research focuses on development of the House form in Maharashtra, aiming to establish the principle behind the generic form and the typical variations in 5 traditional regions that comprises the present day state of Maharashtra, that is Desh, Khandesh, Marathwada, Vidharbha and Konkan. Spatial and distinct architectural styles of the WADA has been taken under here along the exploration of technology adopted for construction. However, this would not be an exhaustive account of all aspects related to this issue which includes sociocultural and political determinants as well. Keywords: Wada Architecture, Vaastu Shastra, Indian traditional architecture, context, cardinal orientation, sustainability.

Scalar field dark matter: impact of supernova-driven blowouts on the soliton structure of low-mass dark matter haloes

ABSTRACT We present the first study on the gravitational impact of supernova feedback in an isolated soliton and a spherically symmetric dwarf scalar field dark matter (SFDM) halo of virial mass $1\times 10^{10}\,\mathrm{M_\odot }$. We use a boson mass $m=10^{-22}\,\mathrm{eV\,c^{-2}}$ and a soliton core $r_\mathrm{ c} \approx 0.7$ kpc, comparable to typical half-light radii of Local Group dwarf galaxies. We simulate the rapid gas removal from the centre of the soliton by a concentric external time-dependent Hernquist potential. We explore two scenarios of feedback blowouts: (i) a massive single burst and (ii) multiple consecutive blowouts injecting the same total energy to the system, including various magnitudes for the blowouts in both scenarios. In all cases, we find one single blowout has a stronger effect on reducing the soliton central density. Feedback leads to central soliton densities that oscillate quasi-periodically for an isolated soliton and stochastically for an SFDM halo. The range in the density amplitude depends on the strength of the blowout; however, we observe typical variations of a factor of $\geqslant$2. One important consequence of the stochastic fluctuating densities is that, if we had no prior knowledge of the system evolution, we can only know the configuration profile at a specific time within some accuracy. By fitting soliton profiles at different times to our simulated structures, we found the (1$\sigma$) scatter of their time-dependent density profiles. For configurations within the 1$\sigma$ range, we find the inferred boson mass is typically less than 20 per cent different from the real value used in our simulations. Finally, we compare the observed dynamical masses of field dwarf galaxies in our Local Group with the implied range of viable solitons from our simulations and find good agreement.

Identifying diversity of patient anatomy through automated image analysis of clinical ultrasounds.

Central venous catheterization (CVC) carries inherent risks which can be mitigated through the use of appropriate ultrasound-guidance during needle insertion. This study aims to comprehensively understand patient anatomy as it is visualized during CVC by employing a semi-automated image analysis method to track the internal jugular vein and carotid artery throughout recorded ultrasound videos. The ultrasound visualization of 50 CVC procedures were recorded at Penn State Health Milton S. Hershey Medical Center. The developed algorithm was used to detect the vessel edges, calculating metrics such as area, position, and eccentricity. Results show typical anatomical variations of the vein and artery, with the artery being more circular and posterior to the vein in most cases. Notably, two cases revealed atypical artery positions, emphasizing the algorithm's precision in detecting anomalies. Additionally, dynamic vessel properties were analyzed, with the vein compressing on average to 13.4%of its original size and the artery expanding by 13.2%. This study provides valuable insights which can be used to increase the accuracy of training simulations, thus enhancing medical education and procedural expertise. Furthermore, the novel approach of employing automated data analysis techniques to clinical recordings showcases the potential for continual assessment of patient anatomy, which could be useful in future advancements.

24-h continuous non-invasive multiparameter home monitoring of vitals in patients with Rett syndrome by an innovative wearable technology: evidence of an overlooked chronic fatigue status.

Sleep is disturbed in Rett syndrome (RTT), a rare and progressive neurodevelopmental disorder primarily affecting female patients (prevalence 7.1/100,000 female patients) linked to pathogenic variations in the X-linked methyl-CpG-binding protein 2 (MECP2) gene. Autonomic nervous system dysfunction with a predominance of the sympathetic nervous system (SNS) over the parasympathetic nervous system (PSNS) is reported in RTT, along with exercise fatigue and increased sudden death risk. The aim of the present study was to test the feasibility of a continuous 24 h non-invasive home monitoring of the biological vitals (biovitals) by an innovative wearable sensor device in pediatric and adolescent/adult RTT patients. A total of 10 female patients (mean age 18.3 ± 9.4 years, range 4.7-35.5 years) with typical RTT and MECP2 pathogenic variations were enrolled. Clinical severity was assessed by validated scales. Heart rate (HR), respiratory rate (RR), and skin temperature (SkT) were monitored by the YouCare Wearable Medical Device (Accyourate Group SpA, L'Aquila, Italy). The average percentage of maximum HR (HRmax%) was calculated. Heart rate variability (HRV) was expressed by consolidated time-domain and frequency-domain parameters. The HR/LF (low frequency) ratio, indicating SNS activation under dynamic exercise, was calculated. Simultaneous continuous measurement of indoor air quality variables was performed and the patients' contributions to the surrounding water vapor partial pressure [PH2O (pt)] and carbon dioxide [PCO2 (pt)] were indirectly estimated. Of the 6,559.79 h of biovital recordings, 5051.03 h (77%) were valid for data interpretation. Sleep and wake hours were 9.0 ± 1.1 h and 14.9 ± 1.1 h, respectively. HRmax % [median: 71.86% (interquartile range 61.03-82%)] and HR/LF [median: 3.75 (interquartile range 3.19-5.05)] were elevated, independent from the wake-sleep cycle. The majority of HRV time- and frequency-domain parameters were significantly higher in the pediatric patients (p ≤ 0.031). The HRV HR/LF ratio was associated with phenotype severity, disease progression, clinical sleep disorder, subclinical hypoxia, and electroencephalographic observations of multifocal epileptic activity and general background slowing. Our findings indicate the feasibility of a continuous 24-h non-invasive home monitoring of biovital parameters in RTT. Moreover, for the first time, HRmax% and the HR/LF ratio were identified as potential objective markers of fatigue, illness severity, and disease progression.

Optimal control strategies for PMSM with a decoupling super twisting SMC and inductance estimation in the presence of saturation

This paper deals with optimal control strategies robustified by a decoupling super-twisting sliding mode control (ST-SMC) for permanent magnet synchronous machines (PMSM). In general, ST-SMC is a robust method for controlling systems and guarantees asymptotic convergence in cases where the upper bound of model uncertainties such as disturbances and parametric uncertainties is not known a priori, if the upper bound of the derivative is known. The proposed optimal control strategy is designed for a constant torque reference whose control is implemented in two control regions: maximum torque per ampere (MTPA) and flux-weakening control. In the proposed analysis, the operating point of the motor can also be in the saturation region, which makes the estimation of Ld and Lq in the proposed optimization procedure of particular interest and also important for the decoupling control implemented with ST-SMC. To compensate for typical parameter variations, adaptive parameter estimation is introduced into the control system using an extended Kalman filter (EKF) in combination with a bivariate polynomial. In order to be able to make an assessment of the control performance of the ST-SMC, a comparison with a conventional PI controller is shown at the end of the paper. Measured results using hardware in the loop (HIL) to validate the results and their detailed discussion and analysis are included.

Comparative Study of Performance Metrics for Smart Inverter Control in Solar PV-Based EV Charging Stations

Photovoltaic (PV) panels harness sunlight as a clean and renewable energy source, providing a sustainable alternative to fossil fuels. In India, PV technology is gaining traction due to its environmental benefits and governmental support. This study analyzes typical PV generation profiles, identifying daily and seasonal variations influenced by factors like cloud cover. Additionally, it investigates the effectiveness of three EV charging strategies—uncontrolled, smart, and vehicle-to-home (V2H)—using rule-based and Model Predictive Control (MPC) algorithms. Simulations reveal that MPC consistently outperforms rule-based control in reducing household costs, with V2H charging showing potential for cost savings during peak electricity pricing. However, the efficacy of control strategies varies across seasons, suggesting the need for adaptive optimization approaches.

It's not easy being green: Comparing typical skin colouration among amphibians with colour abnormalities associated with chromatophore deficits.

Amphibians can obtain their colour from a combination of several different pigment and light reflecting cell types called chromatophores, with defects in one or several of the cells leading to colour abnormalities. There is a need for better recording of colour abnormalities within wild amphibian populations, as this may provide baseline data that can be used to determine changes in environmental conditions and population dynamics, such as inbreeding. In this study, we provide records of several types of chromatophore deficiencies, including those involving iridophores, xanthophores and melanophores, among two Australian tree frog species; the green and golden bell frog, Litoria aurea, and the eastern dwarf tree frog, L. fallax. We explore these colour abnormalities in terms of the chromatophores that have likely been affected and associated with their expression, in combination with typical colour phenotypes, colour variations and colour changes for these species. We intend for our photographs to be used as a visual guide that addresses the need for more accessible information regarding the physical manifestation of different chromatophore defects among amphibians.

A New Rotating Axes Method for Processing High-Resolution Horizontal Velocity Measurements on EM-APEX floats

Abstract A new rotating axes method (RAM) is developed to improve the vertical resolution of the horizontal current velocity measurements u at EM-APEX floats. Unlike the traditional harmonic fitting method (HFM), which yields u averaged in 50-s intervals, RAM decodes and interprets 1-Hz measurements of horizontal seawater velocity , and averages in 12-s windows for removing wind waves with a typical peak frequency ∼ 0.12 Hz. Estimates of u from RAM agree with those from HFM but with a higher vertical resolution of ∼1.5 m, 4 times better than HFM. Note that extracting float signals due to seawater motion needs to assume slow-varying voltage offset ΔΦoffset. The typical variations of estimated ΔΦoffset do not affect the results of u significantly. Estimates of u are excluded when ΔΦoffset fluctuates strongly in time and scatter significantly. RAM is applied to float measurements taken near Mien-Hua Canyon, Taiwan. Composite vertical shear spectra Ψ computed using u from RAM exhibit a spectral slope of −1, as expected for the saturated internal waves in the vertical fine-scale range. The RAM provides EM-APEX float’s horizontal velocity measurements into fine vertical scales and will help improve our understanding of energy cascade from internal wave breaking and shear instability into turbulence mixing.

Cardiorespiratory patterns of male South American sea lions (Otaria flavescens) resting on land.

The goal of this study was to characterize the cardiorespiratory patterns of male South American sea lions (SASLs, Otaria flavescens) resting on land. We recorded respiratory and heart rate (n = 360 individuals studied) by observing the nostrils, chest movements and the impact of the heart on the thoracic wall. The sea lions breathe apneustically with a pause on inspiration, representing 74% of the respiratory cycle. The mean breathing frequency was 3.2 ± 1.0breathsmin-1, with a breathing cycle presenting periods of bradypneas, tachypneas, and long-term post-inspiratory pauses. The normal heart rate (nHR) was 73.4 ± 14.5beats min-1 and no significant differences were observed between age classes. All animals showed variability in HR in relation to respiratory phases (Inspiration: 101.2 ± 18.4beatsmin-1; post-inspiratory pause: 73.4 ± 14.5beatsmin-1; expiration: 64.6 ± 17.7beatsmin-1), consistent with respiratory sinus arrhythmia (RSA). The mean HR (measured during all respiratory phases) was 79.9 ± 22.7beatsmin-1, and was significantly different between age classes. The total duration of respiratory cycle, and duration of both inspiration and expiration, decreased with an increment in ambient temperature, with no variation in the pause duration. Heart rate during pause and expiration was significantly higher during high temperatures. Similar changes in cardiorespiratory patterns have been reported in other pinnipeds. Our results showed ontogenetic differences in development and typical variations with environmental and behavioral variables.

Advanced plant-wide control design tools applied to the fluid catalytic cracker-fractionator benchmark

In this work two advanced multivariable control structure design tools are applied on the recently appeared fluid catalytic cracking (FCC)-fractionator benchmark process. Indeed, the partial least squares-based sum of squared deviations (PLS-based SSD) approach and the control allocation (CA) with measurement combination procedure are proposed here to develop new control policies. The minimally invasive feature of PLS-based SSD, allows to obtain an open-loop steady-state model of the process by using closed-loop normal data and to perform a performance/feasibility assessment of the already installed control structure. In this regard, the procedure identified some global integrity problems of the industrial-based control structure proposed in previous works and, therefore, new plant-wide control structures (with different sizing and input/output pairings) were proposed, where the SSD indexes have improved in the range of 50% to 90% and the matrix conditioning guaranteed. The proposed control structures were dynamically tested under typical set point and disturbance variations.

Minimally invasive presigmoid retrolabyrinthine suprameatal approach (PRSA): A cadaveric study for accessing premeatal anterior inferior cerebellar artery (AICA) aneurysms.

The surgical management of aneurysms involving the proximal third of the anterior inferior cerebellar artery (AICA) usually necessitates complex and invasive approaches, thus posing major challenges. We aimed to investigate the infratentorial presigmoid retrolabyrinthine suprameatal approach (PRSA) as a surgical corridor for premeatal AICA aneurysms. We performed 10 PRSA dissections in five cadaveric heads. Twelve morphometric parameters were measured, analyzed, and categorized into pre-procedural, intra-procedural, and additional parameters. The typical anatomic-radiological characteristics and variations were evaluated, and the related anatomical and radiological parameters were analyzed to predict surgical accessibility. Preoperative anatomic-radiological parameters provide valuable information to select patients with favorable anatomy that may offer appropriate surgical accessibility to the premeatal AICA through a PRSA corridor. The position of the basilar artery from the midline determines the degree of accessibility to the origin of AICA through the infratentorial PRSA. The PRSA for targeting proximal AICA aneurysms was also compared to other surgical approaches based on the available current literature. Premeatal AICA aneurysms can be accessed and clipped through the infratentorial PRSA corridor. This would allow surgeons to avoid the sacrifice of hearing and balance as compared to other available invasive alternative approaches. The selection of the appropriate patients should be based on the individualized preoperative radiological characteristics for both the vascular and bony anatomy.

Experimental Study on the Compressive Strength and Fatigue Life of Cement Concrete under Temperature Differential Cycling

Concrete, as an engineering material with extremely wide applications, is widely used in various infrastructure projects such as bridges, highways, and large buildings. However, structures such as highways and bridges often need to be situated in variable and harsh service environments for long periods. They not only face cyclic reciprocating vehicle loads but also have to contend with the effects of temperature cycling. Therefore, studying the impact and mechanism of temperature differential cycling on the compressive strength and fatigue life of cement concrete has certain theoretical significance and practical value. This study employed a comprehensive experimental design to investigate cement concrete specimens subjected to typical temperature variations (20–60 °C) and different numbers of temperature differential cycling (0, 60, 120, 180, 240, 300). Axial compressive strength tests, ultrasonic tests, and compressive fatigue tests were conducted. The axial compressive strength test measured the compressive strength of the cement concrete. It was found that with an increase in the number of temperature differential cycling, the compressive strength exhibited a trend of an initial increase followed by a decrease: at 60 cycles, the strength increased by 10.8%, gradually declined; returned to near-initial strength at 120 cycles, and continued decreasing, reaching a decline of 19.4% at 300 cycles. The ultrasonic test measured the ultrasound velocity of the concrete specimens after different temperature differential cycling. It revealed a decreasing trend in ultrasound velocity with an increase in times of temperature differential cycling, showing a strong linear relationship between the ultrasound velocity loss and strength loss, confirming the correlation between the degree of concrete strength degradation and internal damage. The compressive fatigue test analyzed the fatigue life variation in cement concrete under different times of temperature differential cycling and stress levels, showing good adherence to the Weibull distribution pattern. Based on the approximation assumptions of log-normal distribution and the Weibull distribution, the Weibull distribution parameters for the compressive fatigue life of cement concrete under temperature differential cycling were obtained.