Macrocephaly Research Articles

Age Structure, Body Size, and Sexual Dimorphism in a High-Altitude Population of Pelophylax ridibundus (Pallas, 1771)

This study aimed to describe the morphological characteristics and age structure of a P. ridibundus population sampled from a high altitude. For this purpose, a total of 54 adult frogs (33 males and 21 females) were collected from Şavşat district, Artvin province, Türkiye. The samples were aged based on skeletochronology method. Furthermore, von Bertalanffy growth curve models were constructed using SVL and weight data. To assess sexual size and shape dimorphism, the measurements of 23 different morphological characters were analyzed using univariate and multivariate statistical techniques. The mean SVL and weight were found to be 78.05 mm and 60.87 g for males and 93.95 mm and 109.61 g for females. The mean age was 3.67 years and 4.05 years for males and females, respectively. The maximum age was found to be 6 years for both sexes. Growth curve models revealed a significant relationship between age, SVL, and weight. A clear female-biased sexual size dimorphism was found in all morphological characters. However, SVL-adjusted values indicated that males had larger head and limb structures resulting from evolutional and sexual pressures associated with reproduction and male–male competition. The shape dimorphism was found only in forelimbs, and it was male-biased and was related to clasping in amplexus.

The role of femoral head size in metal-on-metal hip arthroplasty: analysis of a cohort of 3813 patients with long term follow-up.

Metal-on-metal (MoM) large headed arthroplasties were suggested to decrease failure rates by means of reduced volumetric wear and enhanced implant stability. However, they caused high rates of revisions due to adverse reaction to metal debris, osteolysis, pseudotumor growth, and other issues. The study aims to present the long-term outcomes of MoM arthroplasties on a large cohort of patients, evaluatingthe impact of head sizes on survival rate. All data were retrieved from the regional joint register (Registro dell'Implantologia Protesica Ortopedica, RIPO, Italy). We include in the study all patient who underwent cementless MoM total hip arthroplasties (THAs) between 2000 and 2020, dividing them in two subgroups according to head size (<36mm, ≥36mm). Failures were recorded up to December 31, 2020. Patients lost to follow-up were excluded. A total of 3813 THAs met the inclusion/exclusion criteria. The average follow-up period is 12.4years (0-21years). 178/1625 (or 11.0%) small head MoM THAs and 265/2188 large head ones failed by the end of follow up. Large diameter heads reported lower survival rate (p-value < 0.001), with unexpected higher dislocation rate (1.0 vs. 0.4%). Moreover, large head size was found to increases the risk of metallosis (p-value < 0.0001). Gender, patient's age and the use of modular neck were not correlated with higher failure rates. MoM implants implants do not have the same reliability as other couplings, considering the significantly greater failure/complication rates. However, the knowledge of risks linked to head size is fundamental for establishing the right type of follow-up to the patient and recognize any complications early.

Multiple Paths to a Larger Mouth: Morphological Divergence in Two Island Populations of Australian Tiger Snakes (Notechis scutatus)

AbstractWe studied ontogenetic variation in skull morphology in tiger snakes sampled from mainland South Australia (Coffin Bay), mainland Western Australia (Herdsman Lake), Franklin Island, and Hopkins Island. The snakes from the two islands were selected because of their unusually large absolute body and head size, likely attained as a result of dietary constraints and strong selective pressure during thousands of years of isolation on islands. We performed geometric morphometric analysis of the skulls from these snakes to identify and precisely quantify morphological differences. Island snakes are born larger (trunk length) than mainland snakes, and consequently also tend to have larger absolute head size at birth. The heads of island snakes also show a faster relative growth rate (positive allometry) compared to those of mainland snakes, likely to cope with the large prey items found on these islands. However, the snakes from the two islands differ from each other in terms of morphological change associated with ontogeny, especially with regard to a palatal bone (ectopterygoid), which, compared to mainland snakes, is relatively longer in the snakes from Hopkins Island but shorter in the snakes from Franklin Island. Some morphological traits potentially associated with promoting a larger gape were also observed in one of the mainland populations (Herdsman Lake), consistent with standing variability for selection. Our results reveal that discernible changes in morphology and allometry in skull bones have evolved in island populations of tiger snakes in less than 10 000 years, and suggest that the large heads of island tiger snakes might develop via slightly different paths through morphospace on different islands.

A Dual Detection Head YOLO Model With Its Application in Wheat Ear Recognition

The spike number(SN) per unit area is an important indicator for measuring wheat yield. The use of AI to detect and count wheat ears is increasingly valued by researchers. In order to improve the accuracy of wheat ear recognition, the model is deployed on limited mobile devices to achieve accurate estimation of wheat yield. This paper proposes a lightweight hybrid design network Wheat-YoloNet based on improved YOLOv8 for wheat ear recognition. On the basis of the YOLOv8 network structure, we only retain small and large object detection heads, reducing the number of network parameters while ensuring detection performance. We added CBAM attention mechanism module to Backbone to improve the feature extraction performance of the model and introduce Wise-IoU to balance the samples. Compared with the YOLOv8n baseline model, the improved model has reduced parameter count by 33.3%, outperforming other comparison object detection algorithms, and can be deployed and run on devices with limited computing power.

Risk assessment method for civil aircraft approach and landing at high plateau based on QAR data

Civil aircraft approach and landing at high altitude is a high-risk stage of plateau flight. In order to effectively implement the risk identification and grade judgment of approach and landing at high altitude, an LSTM-DNN deep learning risk assessment method based on variable fuzzy recognition with weights removed is proposed. This method is first based on the high-altitude flight data recorded by the quick access recorder (QAR), and draws on the civil aircraft flight quality monitoring project specification (FOQA) consultation notice and industry QAR monitoring standards. Combined with the indicator importance analysis and Delphi expert survey, five key monitoring items are extracted as the risk assessment indicators of civil aircraft approach and landing at high altitude, including large heading change during landing, low track, large descent rate during 2000-1000 ft approach, vertical acceleration at touchdown, and large descent rate during 500-50ft approach. Then, in order to overcome the subjective bias of the evaluation indicator weight, the weight of the evaluation indicator is determined by the weight removal method, and the risk grade membership function is constructed based on the variable fuzzy recognition method. Finally, a risk assessment model for civil aircraft approach and landing at high altitude based on LSTM-DNN is established. Taking the Chengdu-Lhasa approach and landing segment as an example, the QAR data was extracted to train and test the risk assessment model, and the results were compared with those of Logistic multivariate regression, support vector machine (SVM) and other evaluation methods. The results show that the average recognition rate of the LSTM-DNN deep learning model based on variable fuzzy recognition with weights removed reaches 94.18%, and the highest can reach 94.79%, which verifies the objective effectiveness of the risk assessment method.

Investigating the after effect of head-tracked movement on externalization for varying sound sources in binaural synthesis.

Binaural audio reproduction aims to create a realistic auditory experience for the listener through headphones. However, front and rear sound sources are often internalized (perceived inside the head) rather than externalized (perceived outside the head). Previous studies have shown that large head movements can significantly improve externalization, and that this improvement can persist even after head movements have stopped. This study examined how head-tracked movements influence the perception of sound externalization depending on the nature of the sound sources. The stimuli consisted of a first ``head movement" part during which the participants had to either perform a head movement or stay still, followed by a "rating" part where they evaluated externalization without moving. The sound sources during the ``rating" part could be similar, slightly different, or very different from the source during the head movement part. Results demonstrated that head-tracked movements effectively heightened externalization perception for all types of sources immediately after the movement. The type of source (female voice, male voice, or pink noise) did not affect perceived externalization. These findings suggest that the externalization enhancement induced by head-tracked movement persists after the movement ends even when encountering a different sound source.

Analysis of variable speed operating range of centrifugal pump with large flow and wide head variation

Abstract The advantages of variable speed centrifugal pump include its broad operating range, wide operating efficiency zone, high operational stability, and regulative characteristics of input power. When pump station has characteristics such as large flow rate changes, large pump head changes, the conventional fixed speed centrifugal pump cannot meet requirements of safe and stable operation under characteristic pump conditions. In order to ensure the safe and stable operation of the pump station within the operation range, the variable speed operation strategy of centrifugal pumps is adopted to enhance its wide amplitude adjustment capability and efficient operation. This paper uses an 8MW centrifugal pump with wide head range in China to analyze the factors that influence the operating range of pump unit in detail. The results indicate that the variable speed pump unit’s safe and effective operating range is determined by the cavitation margin, hump margin, speed range, and pump maximum input power. The hydraulic design can improve the hump safety margin and cavitation characteristics of the operating zone, and then expand the operating range of the pump unit. Meanwhile, increasing the static suction head, reducing the hump margin, controlling pump head amplitude, and appropriately increasing the maximum input power limit are the best ways to extend centrifugal pump’s operating range and improve its adjustable capability. The results can provide reference for parameter selection and hydraulic design of large variable centrifugal pump in the future.

A comparative performance study of terminal control strategy for the multi-split backplane cooling system in data centers

Multi-split backplane cooling, a typical rack-level cooling technology, has the advantage of solving local hot-spot problems with huge energy-saving potential. These systems adopt the multi-split mode, and the operation effect is affected by terminal control performance. However, there are factors in the operation process, such as superheat degree (SH), rack airflow, evaporating/condensing pressures, etc., which improve the control complication, particularly under large head load differences among different terminals. Therefore, appreciative control strategies for outlet air temperatures of terminal evaporators, including single-loop control limited by minimum stable superheat degree (SLC) and fan/electronic expansion valve (EEV) double-loop control (DLC), are proposed considering that cooling performance can be affected by both refrigerant flow and airflow. Then, comparative simulation studies are carried out to evaluate energy efficiency, control effect, and feasibility under the condition of different server heat distribution characteristics. Results indicate that the DLC strategy achieves 23% higher energy efficiency than the SLC strategy with a better temperature control effect when the inlet air temperature (IAT) difference between terminal evaporators is within ±5K. The SLC strategy has better reliability by more stable control of SH at IATs below 42°C, but it may lead to cooling failure when IATs exceed 42°C. An insufficient liquid supply problem may happen to the evaporator adopting the DLC strategy when the IAT is too high, which can be solved by adjusting the pressure differential between the evaporator and condenser. Moreover, the DLC system exhibits intense coupling effects, and how to decouple it is worthy of further study.

Clinical Use of Bedside Portable Ultra-Low-Field Brain Magnetic Resonance Imaging in Patients on Extracorporeal Membrane Oxygenation: Results From the Multicenter SAFE MRI ECMO Study.

Early detection of acute brain injury (ABI) at the bedside is critical in improving survival for patients with extracorporeal membrane oxygenation (ECMO) support. We aimed to examine the safety of ultra-low-field (ULF; 0.064-T) portable magnetic resonance imaging (pMRI) in patients undergoing ECMO and to investigate the ABI frequency and types with ULF-pMRI. This was a multicenter prospective observational study (SAFE MRI ECMO study [Assessing the Safety and Feasibility of Bedside Portable Low-Field Brain Magnetic Resonance Imaging in Patients on ECMO]; NCT05469139) from 2 tertiary centers (Johns Hopkins, Baltimore, MD and University of Texas-Houston) with specially trained intensive care units. Primary outcomes were safety of ULF-pMRI during ECMO support, defined as completion of ULF-pMRI without significant adverse events. Of 53 eligible patients, 3 were not scanned because of a large head size that did not fit within the head coil. ULF-pMRI was performed in 50 patients (median age, 58 years; 52% male), with 34 patients (68%) on venoarterial ECMO and 16 patients (32%) on venovenous ECMO. Of 34 patients on venoarterial ECMO, 11 (22%) were centrally cannulated and 23 (46%) were peripherally cannulated. In venovenous ECMO, 9 (18%) had single-lumen cannulation and 7 (14%) had double-lumen cannulation. Of 50 patients, adverse events occurred in 3 patients (6%), with 2 minor adverse events (ECMO suction event; transient low ECMO flow) and one serious adverse event (intra-aortic balloon pump malfunction attributable to electrocardiographic artifacts). All images demonstrated discernible intracranial pathologies with good quality. ABI was observed in 22 patients (44%). Ischemic stroke (36%) was the most common type of ABI, followed by intracranial hemorrhage (6%) and hypoxic-ischemic brain injury (4%). Of 18 patients (36%) with both ULF-pMRI and head computed tomography within 24 hours, ABI was observed in 9 patients with a total of 10 events (8 ischemic, 2 hemorrhagic events). Of the 8 ischemic events, pMRI observed all 8, and head computed tomography observed only 4 events. For intracranial hemorrhage, pMRI observed only 1 of them, and head computed tomography observed both (2 events). Our study demonstrates that ULF-pMRI can be performed in patients on ECMO across different ECMO cannulation strategies in specially trained intensive care units. The incidence of ABI was high, seen in 44% of ULF-pMRI studies. ULF-pMRI imaging appears to be more sensitive to ABI, particularly ischemic stroke, compared with head computed tomography.

In THA, Large Metal Heads in Thin Polyethylene Liners Versus Standard Metal Heads Did Not Differ for Liner Wear or Most PROs at 5 Years

In THA, Large Metal Heads in Thin Polyethylene Liners Versus Standard Metal Heads Did Not Differ for Liner Wear or Most PROs at 5 Years

Performance analysis of a novel multi-machine compensable pumped hydro compressed air energy storage system

Many pumped hydro compressed air energy storage systems suffer from large head variations in the hydraulic machinery. To address this defect, this study proposes a multi-machine compensable pumped hydro compressed air energy storage system and reveals its operational, energy, exergy, and economic performances. First, the energy, exergy, and economic models of the system are established. Second, the operational characteristics of each component are analyzed. Third, the energy, exergy, and economic performances of the system are presented. Finally, the impact of operating pressure on the energy and exergy performance is analyzed. The results indicate that air pressure variations of 0.300 MPa/0.256 MPa in Tank 1 are reduced to head variations of 11.0 m/12.7 m at the hydraulic machinery, respectively. Furthermore, the round-trip efficiency, exergy efficiency, and energy storage density reached were 0.672, 0.694, and 0.038 kW·h/m3, respectively. The most significant work wastage and exergy loss occurred in Tanks 1 and 2, contributing to 48.5 % and 37.5 % of the total, respectively. As the operating pressure increases, the round-trip and exergy efficiencies decrease, and the energy storage density increases. In this study, the head amplitude at the hydraulic machinery under charging and discharging conditions was reduced by nearly 2/3 and 1/2, respectively.

A new miniaturized species of leaf chameleon, genus Brookesia, from a littoral forest fragment in eastern Madagascar

The number of species of miniaturized chameleons of the genus Brookesia, subgenus Evoluticauda, known to science has witnessed a dramatic increase over the past 15 years, due to the discovery of multiple microendemic species of very strong genetic divergence. So far, no described Evoluticauda species are known from the littoral forest of Madagascar’s east coast, one of the most threatened habitat types of the island. Here, we report on the discovery of a new species of Evoluticauda occurring in the littoral forest at Ankanin’ny Nofy, a touristic site at about sea level and close to Vohibola forest where probably the same species occurs. The new species, Brookesia nofy sp. nov., is sister to B. ramanantsoai which occurs in mid-altitude and highland forests (800–1300 m a.s.l.) at a similar latitude of eastern Madagascar, but differs from this species by an enormous genetic divergence in both mitochondrial and nuclear genes (8.1–9.4% uncorrected pairwise distance in the 16S rRNA gene, 1.8–2.5% in c-mos), a relatively shorter tail, a different arrangement of cephalic ridges, and probably smaller body size and relatively larger head. The discovery of B. nofy sp. nov. emphasizes the importance of conserving Madagascar’s last remaining fragments of littoral forest.

Research on the gap value and optimization of 500 kV large span tower head

Research on the gap value and optimization of 500 kV large span tower head

Assessing the influence of dose modulation on water equivalent diameter estimation in pediatric head CT imaging

Pediatric head computed tomography (CT) scans necessitate precise determination of radiation dose to optimize image quality while minimizing patient exposure. This study explores the influence of head size variation on radiation dose and image quality using phantom and patients set, aiming to investigate the efficacy of Automatic Exposure Control (AEC) in dose modulation. Image noise and radiation dose were assessed using with and without AEC, maintaining a constant tube current of 180 mA. The correlation between CT dose index volume (CTDIvol) and water-equivalent diameter (Dw) was examined across 134 image sets, revealing an exponential relationship indicative of AEC's contribution to elevated radiation exposure in larger heads. Furthermore, a slice-based analysis demonstrated a consistent variation in tube current along the slice location, effectively modulated by Dw. However, discrepancies in tube current were observed in the caudal region, suggesting the influence of factors beyond section size. Refinement of analysis improved curve fitting, highlighting the importance of section size in dose modulation. AEC proved essential in maintaining image quality consistency across slices, with inactive AEC resulting in lower image noise in cranial slices. These findings highlight the significance of AEC-based dose modulation in pediatric head CT to ensure optimal image quality while minimizing radiation exposure, emphasizing the need for comprehensive understanding and implementation of AEC systems from different manufacturers.

Gaidropsarus mauritanicus (Gadiformes, Gaidropsaridae) a new three-bearded rockling from a deep-water coral ecosystem with a genetically verified biogeographical distribution of the genus and notes to its ecology and behavior.

Gaidropsarus mauritanicus sp. nov. is described from one specimen collected using a grab sample from the Tanoûdêrt Canyon (ca. 20° N) off Mauritania at a depth of 595 m. The new species was further observed during eight remotely operated vehicle (ROV) dives along the Mauritanian slope southwards down to the Tiguent Coral Mound Complex (~17° N) in a bathymetric range between 613 and 416 m. It can be distinguished from congeners by a combination of characteristics, including large eyes (38.1% head length [HL]), large head (25.8% standard length [SL]), elongated pelvic fins (35.7% SL), low number of vertebrae (44), and coloration (pinkish with a dorsal darker brownish hue and bright blotches along the dorsal-fin base). A species-delimitation analysis performed with available cytochrome c oxidase subunit 1 (COI) sequences affiliated to the genus Gaidropsarus additionally supported the validity of the new species. Video analyses showed a deep-water coral-associated and protection-seeking behavior, which may explain why the species has remained undescribed until now. Additional ROV footage from separate deep-water coral sites in the North Atlantic and Mediterranean Sea further highlights the ecological behavior and hidden diversity of bathyal three-bearded rocklings. Here, we additionally discuss the biogeographical distribution of all genetically verified Gaidropsarus spp. in combination with genetic data and morphological characters. G. mauritanicus sp. nov. is closely related to a species from Tasmania (43° S), a geographical point furthest among the studied samples, which may hint to an important influence of (paleo-) oceanography on the distributions of Gaidropsarus species.

Individual dietary specialization and intraspecific morphological divergence of an endemic fish species: the case of Glanidium ribeiroi in the Iguassu ecoregion

ABSTRACT Because of the importance of information about endemic species and global biodiversity ecoregion, we tested the hypothesis that individuals of Glanidium ribeiroi (endemic species in the Iguassu ecoregion) are specialists and that this specialization decreases with increasing body size, especially concerning the size of the mouth and head, which can be limiting for the quantity and size of prey consumed by smaller individuals. Fish sampling was conducted monthly using gill nets and longlines from 2013 to 2016 in the main channel of the Iguaçu River and two tributaries. We observed the consumption of aquatic insects by smaller individuals and seeds, unidentified fish, and Decapoda by larger individuals. Individual dietary specialization was high and related to head width. The morphological traits of smaller-sized individuals were related to displacement and movement (larger peduncle), and the larger-sized individuals were related to high performance in the exploitation and prey acquisition (larger head and mouth, dorsal eyes, longer intestines). Our results highlight the importance of assessing individual variations within a population, favoring an understanding of population dynamics. In addition, morphological differences may imply differences in the use of habitat and food resources between individuals of larger and smaller body sizes and influence individual specialization.

Chimeric Versus Multiple Simultaneous Free Flaps for Head and Neck Reconstruction.

To describe our experience with chimeric flaps and to assess the surgical outcomes and postoperative complications associated with chimeric flaps compared to multiple flaps. Patients undergoing chimeric and multiple simultaneous free tissue transfer between June 2016 and October 2023 were retrospectively reviewed. The primary outcome of interest was the complication rate. Major complications required takeback to the operating room, hospital readmission, or transfer to the intensive care unit. Minor complications were managed conservatively. Secondary outcomes included operative time, length of hospitalization, and flap survival. Academic tertiary care center. Our analysis included 113 patients (chimeric n = 38, multiple n = 75). We found no significant difference in operative times or minor complications. Chimeric flaps were associated with a shorter length of hospitalization. The major complication rate was higher for chimeric flaps (42.1% vs 22.7%, P = .03), but each cohort only had 1 instance of total flap loss. The complexity of large head and neck defects poses a reconstructive challenge for microvascular surgeons. Our findings suggest that chimeric and multiple flaps both produce acceptable complication rates when used appropriately. Differences in complication rates may reflect differences in utilization. The chimeric flap remains a valuable option for those with prior radiation or radical resection, but it remains unclear the degree to which they lessen the inherent risk of postoperative complications within this population. Each technique must be weighed in context of the patient's reconstructive profile and the institution's surgical capabilities to optimize long-term outcomes.

Short-term outcomes with routine use of size ≥40 femoral heads in THA: A retrospective cohort study

BackgroundUsing larger femoral heads during total hip arthroplasty (THA) may result in a more stable hip. Greater volumetric wear and frictional torque, however, may result in increased postoperative complications. The purpose of this study was to compare outcomes of patients with femoral head size ≥40 mm compared to those with femoral head size <40 mm. Materials and methodsA retrospective chart review of 504 THAs performed by a single surgeon at a single institution from 2009 to 2016 was conducted. Following exclusions, 131 THAs were identified with femoral heads ≥40 mm and 348 THAs were identified with femoral heads <40 mm. In addition to demographic data, all postoperative complications were recorded. Plain radiographs were used to rule out/in periprosthetic osteolysis and/or acetabular loosening. Chi-square tests and Student's t-tests were used to compare categorical and continuous variables, respectively. ResultsMean follow-up period for the entire cohort was 5.5 years. Complications with ≥40 mm femoral heads included 1 superficial infection and 1 deep periprosthetic joint infection (PJI). There were no cases of dislocation, osteolysis, acetabular loosening, or trunnionosis. In contrast, complications with <40 mm femoral heads included 9 dislocations and 7 PJIs. ConclusionThe routine use of large femoral heads (≥40-mm) during THA appears to be a safe option for patients at short-term clinical follow-up. Notably, 0 patients had a clinical course complicated by dislocation, osteolysis, acetabular loosening, or trunnionosis. Level of evidenceLevel III Retrospective Cohort Study.

Does habitat modification impact morphology, performance, and inflammatory responses in an amphibian with limited dispersal capacity (Lisssotriton helveticus)?

The environment of an organism exerts selective pressures that affect mobility, feeding, reproduction as well as predator-prey and conspecific interactions. Land use changes induced by human activities modify these selective pressures and may result in the adaptation of organisms. Amphibians are ectotherms that typically show a biphasic life cycle with an aquatic and terrestrial phase, which makes them particularly sensitive to environmental change. We studied the impact of habitat modifications on palmate newt populations in the Ile de France region across four types of habitats: urban, mixed, agricultural, and natural with at least two replicates for each habitat type. We measured the morphology of newts using callipers, quantified maximal running and swimming speed and acceleration using high-speed video recordings, and quantified the swelling of the hind limb linked to an inflammatory reaction. Our results show that in urban habitats, newts are larger and heavier and have a better body condition. Females, moreover, have a larger head in natural habitats, possibly due to diet specialisation of females during the breeding season. In mixed and agricultural habitats, newts have longer limbs and show a tendency to run faster, possibly associated with the selective pressures on movement in mixed habitats. Differences in inflammatory responses were observed between sexes but not habitat types. Overall, our results show differences in morphology and trends for differences in performance in newts living in different habitats suggesting that animals are adapting to human-induced changes in their environment.

Isolation of lytic bacteriophages and their relationships with the adherence genes of Staphylococcus saprophyticus

ObjectiveThis study aimed to introduce a lytic bacteriophage against Staphylococcus saprophyticus from wastewater in Gorgan, northern Iran.ResultsThe vB_SsapS-46 phage was isolated from urban wastewater and formed round and clear plaques on bacterial culture. It was visualized by electron microscopy and had a large head (approximately 106 nm) and a long tail (approximately 150 nm), indicating that it belongs to the Siphoviridae family. The host range of vB_SsapS-46 was determined using a spot test on 35 S. saprophyticus clinical isolates, and it was able to lyse 12 of the 35 clinical isolates (34%). Finally, the relationship between phage sensitivity and adherence genes was assessed, revealing no significant correlation between phage sensitivity and the frequency of adherence genes. The vB_SsapS-46 phage can be used alone or in a mixture in future studies to control urinary tract infections caused by this bacterium, especially in the elimination of drug-resistant pathogens.