bluuebunny/crossref_metadata_2025 huggingface dataset:
No evidence hunting bait increases American black bear population growth in Maine, USA
Authors: Morin Dana J. , Vashon Jennifer H. , O'Neal Matthew , Hostetter Nathan J. , Flaherty Elizabeth A.
Published: October 2024

American black bear (Ursus americanus) populations are increasing throughout much of North America. Use of multiple harvest methods, including hunting over bait, is intended to increase harvest success rates to meet harvest and population management objectives. However, black bear population growth can be influenced by food availability, and some speculate the use of bait may inadvertently increase bear abundance through food resource supplementation. We collected hair from black bears captured from 2005–2019 and a selection of potential food items, including those used as bait from 3 study areas in Maine, USA, with different levels of human influence. We used stable isotope analysis of the black bear hair and food item samples to evaluate the contribution of different identified food groups to the diet of individual bears. We found no evidence that greater contribution of human food resources, including bait, increased the number of cubs per litter for reproductive females or that human foods comprised a greater part of the diet in years when natural food resources were less abundant. Approximately 69% of black bear harvest occurred over bait. We found the probability of reproductive‐age females to be harvested increased with average representation of human foods with high carbon enrichment (including bait) in their diet, but the relationship was weak, likely because of sampling constraints. Additionally, the probability of being harvested was greater in years when natural food resources were scarce. We conclude that bait is not available on the landscape in large enough amounts or for a sufficient amount of time in Maine to substantially influence female reproduction. Our results indicate hunting over bait is an effective tool in a state that is attempting to maintain a stable bear population via harvest, and dispels conjecture that hunting over bait may increase cub production and offset the intention of harvest.
Transitory sensitivity in automatic chemical kinetic mechanism analysis
Authors: Johnson Matthew S. , McGill Charles J. , Green William H.
Published: October 2024

Detailed chemical kinetic mechanisms are necessary for resolving many important chemical processes. As the chemistry of smaller molecules has become better grounded and quantum chemistry calculations have become cheaper, kineticists have become interested in constructing progressively larger kinetic mechanisms to model increasingly complex chemical processes. These large kinetic mechanisms prove incredibly difficult to refine and time‐consuming to interpret. Traditional sensitivity analysis on a large mechanism can range from inconvenient to practically impossible without special techniques to reduce the computational cost. We first present a new time‐local sensitivity analysis we term transitory sensitivity analysis. Transitory sensitivity analysis is demonstrated in an example to accurately identify traditionally sensitive reactions at an 18,000x speed up over traditional sensitivities. By fusing transitory sensitivity analysis with more traditional time‐local branching, pathway, and cluster analyses, we develop an algorithm for efficient automatic mechanism analysis. This automatic mechanism analysis at a time point is able to identify the reactions a target is most sensitive to using transitory sensitivity analysis and then propose hypotheses why the reaction might be sensitive using branching, pathway, and cluster analyses. We implement these algorithms within the reaction mechanism simulator (RMS) package, which enables us to report the automatic mechanism analysis results in highly readable text formats and in molecular flux diagrams.
Variability of PAH Patterns in Upper Forest Soil (Sub)horizons—A Case Study From South‐Central Poland
Authors: Dołęgowska Sabina , Sołtys Agnieszka , Krzciuk Karina , Wideł Dariusz , Michalik Artur
Published: October 2024

Polycyclic aromatic hydrocarbons (PAHs) are a class of contaminants characterized by their persistent and toxic nature. This study examines the variability in PAH distribution patterns in the upper layers of forest soils, focusing on the influence of different characteristics of individual soil (sub)horizons. A total of 130 samples were collected from five forest areas in south‐central Poland and analyzed for the 16 priority PAHs. Samples were taken from the organic fermentative‐humic (Ofh), humic (A), and humic‐eluvial (AE) (sub)horizons. The highest mean concentrations of total PAHs were found in the subhorizon‐Ofh (Ofh—1547 μg kg−1, A—1103 μg kg−1, AE—109 μg kg−1). The PAH content was significantly correlated with SOM content and pH, but this correlation was only significant in the horizon‐A. The percentage contributions of 3‐, 4‐, 5‐, and 6‐ring compounds to the total PAHs varied among the investigated soil (sub)horizons. The subhorizon‐Ofh had the highest percentage contribution of 6‐ring PAHs, 4‐ and 5‐ring PAHs were most prevalent in the horizon‐A, while 3‐ring compounds in the horizon‐AE. The variability in PAH patterns was also reflected in individual PAH ratios (BaA/BaA+Chr, IcdP/IcdP+BghiP), confirming the different behavior of 4‐, 5‐, and 6‐ring compounds in these (sub)horizons. This suggests that the retention of PAHs in the investigated (sub)horizons is influenced by several factors, including pH, degree of SOM decomposition, and mineral fraction, each to a different extent. Our findings reveal significant knowledge gaps regarding the behavior and accumulation of PAHs in soil (sub)horizons, underscoring the need for further research.
The Inhibitory Tendency of Calamagrostis epigejos and Solidago spp. Depends on the Successional Stage in Postindustrial Vegetation
Authors: Anibaba Quadri A. , Dyderski Marcin K. , Woźniak Gabriela , Jagodziński Andrzej M.
Published: October 2024

In spontaneously vegetated postindustrial areas, we have limited knowledge of whether the known inhibitory tendencies of herbaceous species—Calamagrostis epigejos and Solidago spp.—vary across successional stages. Our study fills this knowledge gap to assess the inhibitory role of the invasive alien and expansive native species with known behavior from the literature. Specifically, we hypothesized: (i) there will be an inhibitory effect of these species on diversity across successional classes; (ii) the effect of a species will depend on the successional class due to abiotic requirements of plant communities in each successional class. We recorded vascular plant species and their abundance across 400 plots on post‐coal mine heaps in Upper Silesia, Poland. We classified spoil heaps into three successional classes (early‐stage; mid‐stage; late‐stage). We calculated plant community taxonomic, functional, and phylogenetic diversity and, using generalized linear mixed‐effects models, we estimated predictors of diversity indices across successional classes. While we found no limiting effects of these species on diversity indices across successional classes, the effects of a species depended on the successional stage. We found the impacts of Calamagrostis and Solidago cover on diversity indices in the mid‐successional stage. This implies that the early‐successional stage is controlled by the lottery (random) model of community assembly. However, in the mid‐successional stage, the competitive exploitation mechanism is evident, resulting in declines in diversity indices. Thus, the impacts of Calamagrostis and Solidago on diversity indices are evident in the mid‐successional stage.
Association Between Health Behaviors and Mental Health Among Airline Pilots
Authors: Wilson Daniel , Driller Matthew , Johnston Ben , Gill Nicholas
Published: October 2024

Background

Lifestyle behaviors including physical activity, sleep, nutrition, smoking, and alcohol consumption are independently associated with health, yet the relationship between these behaviors and mental health has not been explored among airline pilots. The aim of this study was to measure the association between health behaviors and mental health.

Methods

A cross‐sectional study was conducted among 502 airline pilots. The primary outcome measure was the mental component score (MCS), derived from the Short Form Health Survey 12v2. We collected information regarding age, sex, ethnicity, height, body mass, alcohol consumption, tobacco smoking status, moderate‐to‐vigorous physical activity (MVPA), fruit and vegetable intake, and sleep duration.

Results

After controlling for demographic and anthropometric parameters, MVPA, fruit and vegetable intake, and sleep duration were positively correlated with MCS (p ≤ 0.001), and alcohol consumption and tobacco smoking were negatively correlated with MCS (p ≤ 0.001). Multiple linear regression analyses revealed alcohol consumption was the strongest predictor of MCS (β = −0.308, p ≤ 0.001), followed by smoking (β = −0.236, p ≤ 0.001), MVPA (β = 0.233, p ≤ 0.001), sleep (β = 0.148, p ≤ 0.001), and fruit and vegetable intake (β = 0.097, p = 0.003).

Conclusion

The results suggest that greater physical activity, sleep duration, and fruit and vegetable intake are associated with better mental health. Meanwhile, excessive alcohol consumption and tobacco smoking undermine mental health status.
ASLO Opportunities for Students and Early Career Professionals in Aquatic Sciences
Authors: Franco‐Santos Rita M , Bizic Mina , Chen Robert F , Cuker Benjamin , Davis Jeanette , Falkenberg Laura J , Gradoville Mary R , Kambikambi Manda , Kemp Paul F , Kreuser Abigail , Peck Erin K , Schieler Brittany M
Published: October 2024

Students and early career researchers/professionals (ECRs) must increasingly acquire a variety of skills and expand their collaborative networks to become more competitive as they apply for jobs and grants. Funding for skills training and overall availability of opportunities can, however, pose a challenge to this career plan. The Association for the Sciences of Limnology and Oceanography (ASLO) is proud to support the professional development of member and non‐member students and ECRs by offering a myriad of skill‐building programs. These include opportunities to: receive mentoring, travel to ASLO events, expand networks, conduct outreach projects, research exchanges, and internships, better understand scientific publishing, and exercise leadership within the society. In addition, ASLO recognizes the contribution of member students and ECRs to their communities, field, and to the society. Participation in ASLO‐sponsored programs can, thus, assist in the successful transition of students to ECRs, and of ECRs to independent researchers.
Augmented reality experiences: Consumer‐centered augmented reality framework and research agenda
Authors: Barta Sergio , Gurrea Raquel , Flavián Carlos
Published: October 2024

Since the launch of Pokémon Go, augmented reality (AR) has been one of the main research areas within new technologies. Integrating digital elements into the physical world presents exceptional opportunities for different sectors, enabling enhanced interactions and experiences. This study conducts a systematic review of AR literature, highlighting the main theories, theoretical frameworks, and research methodologies employed. It also classifies the main types of AR devices and the diverse contexts in which they are applied. Through a comprehensive thematic analysis, four principal areas of current research are identified: (1) media characteristics and consumer outcomes, (2) psychological influential factors and outcomes, (3) AR app features and technology adoption, and (4) recommendations for implementation in the industry and advantages. Furthermore, the study provides key insights and introduces the consumer‐centered AR framework. The article concludes by proposing a future research agenda, highlighting prospective studies that can contribute from the perspective of the content, context, device, and consumer, as well as avenues for future research from a methodological perspective.
Hepatitis B Virus X Protein Contributes to Hepatocellular Carcinoma via Upregulation of KIAA1429 Methyltransferase and mRNA m6A Hypermethylation of HSPG2/Perlecan
Authors: Sivasudhan Enakshi , Zhou Jingxian , Ma Jiongming , Wang Yuanyuan , Liu Siying , Khan Faez Iqbal , Lu Zhiliang , Meng Jia , Blake Neil , Rong Rong
Published: October 2024

Chronic hepatitis B virus (HBV) remains to be the most common risk factor of hepatocellular carcinoma (HCC). While previous work has primarily focussed on understanding the direct and indirect mechanisms of Hepatitis B virus X protein (HBx)‐mediated hepatocarcinogenesis, from genetic and epigenetic perspectives, its influence on RNA modification mediated onset of liver malignancies is less well understood. This study explored the role of HBV‐encoded HBx in altering the m6A methylome profile and its implications on the pathogenesis of HCC. We established HBx‐expressing stable HCC cell lines, Huh7‐HBx and HepG2‐HBx, and explored the transcriptomic and epitranscriptomic profiles by RNA‐seq and MeRIP‐seq, respectively. Preliminary results suggest that HBx promotes liver cell proliferation, migration, survival and overall m6A methylation in HCC cells and is involved in modulating the extracellular matrix. We show that HBx mediates liver cell transformation by upregulating KIAA1429 methyltransferase. HBx also drives the expression and hypermethylation of the extracellular matrix protein HSPG2/Perlecan and promotes tumourigenesis. Furthermore, we observed a potential interaction between KIAA1429 and HSPG2 in HCC liver cancer cells and demands further investigation.
Progressive cancer targeting by programmable aptamer‐tethered nanostructures
Authors: Mohammadi Fatemeh , Zahraee Hamed , Zibadi Farkhonde , Khoshbin Zahra , Ramezani Mohammad , Alibolandi Mona , Abnous Khalil , Taghdisi Seyed Mohammad
Published: October 2024

Scientific research in recent decades has affirmed an increase in cancer incidence as a cause of death globally. Cancer can be considered a plurality of various diseases rather than a single disease, which can be a multifaceted problem. Hence, cancer therapy techniques acquired more accelerated and urgent approvals compared to other therapeutic approaches. Radiotherapy, chemotherapy, immunotherapy, and surgery have been widely adopted as routine cancer treatment strategies to suppress disease progression and metastasis. These therapeutic approaches have lengthened the longevity of countless cancer patients. Nonetheless, some inherent limitations have restricted their application, including insignificant therapeutic efficacy, toxicity, negligible targeting, non‐specific distribution, and multidrug resistance. The development of therapeutic oligomer nanoconstructs with the advantages of chemical solid‐phase synthesis, programmable design, and precise adjustment is crucial for advancing smart targeted drug nanocarriers. This review focuses on the significance of the different aptamer‐assembled nanoconstructs as multifunctional nucleic acid oligomeric nanoskeletons in efficient drug delivery. We discuss recent advancements in the design and utilization of aptamer‐tethered nanostructures to enhance the efficacy of cancer treatment. Valuably, this comprehensive review highlights self‐assembled aptamers as the exceptionally intelligent nano‐biomaterials for targeted drug delivery based on their superior stability, high specificity, excellent recoverability, inherent biocompatibility, and versatile functions.
How Does AI Affect the Pay Gap Within Firms: Mechanism Analysis Based on Personnel Structure and Corporate Investment
Authors: Wu Qiang
Published: October 2024

This study examines how AI impacts the internal pay gap within enterprises. Using data from listed companies in China and a panel data two‐way fixed effect model, findings reveal that AI widens pay gap, with executives in AI‐applied companies earning 0.327 times more than average employees. AI increases executive pay while hindering employee salary growth, especially in nonmanufacturing and private firms. Labor substitution AI reduces employee compensation growth, whereas labor enhancement AI boosts executive pay without affecting employee compensation. AI also influences personnel structure and enterprise investment in fixed assets and R&D, highlighting its “job substitution effect” and “productivity effect”.
Clinical, Preclinical, and Educational Applications of Robotic‐Assisted Flap Reconstruction and Microsurgery: A Systematic Review
Authors: Awad Laura , Bollen Edward , Reed Benedict , Langridge Benjamin J. , Jasionowska Sara , Nikkhah Dariush , Butler Peter E. M. , Ponniah Allan
Published: October 2024

Introduction

Microsurgery and super‐microsurgery allow for highly technical reconstructive surgeries to be performed, with repairs of anatomical areas of less than 1 mm. Robotic‐assisted surgery might allow for further advances within microsurgery, providing higher precision, accuracy, and scope to operate in previously inaccessible anatomical areas. However, robotics is not well‐established within this field.

We provide a summary of the clinical and preclinical uses of robotics within flap reconstruction and microsurgery, educational models, and the barriers to widespread implementation.

Methods

A systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses was conducted of PubMed, Medline, and Embase. Preclinical, educational, and clinical articles were included.

Results

One thousand five hundred and forty‐two articles were screened; 87 articles met the inclusion criteria across flap harvest, flap/vessel pedicle dissection, vascular anastomosis, and nerve repair. The literature presents several potential benefits to the surgeon and patient such as high cosmetic satisfaction, minimally invasive access with reduced scarring (flap harvest), and low complication rates. Lack of haptic feedback was reported by authors to not impede the ability to perform vessel anastomosis; however, this required further investigation. A steep learning curve was identified, particularly for microsurgeons embarking upon robotic‐assisted surgery.

Conclusion

Robotic‐assisted surgery can potentially enhance microsurgery and flap reconstruction, with feasibility demonstrated within this review, up to anastomosis of 0.4 mm in diameter. However, there is a lack of sufficiently powered comparative studies, required to strengthen this statement. To increase accessibility to robotic surgery for plastic and reconstructive surgeons, educational opportunities must be developed with standardized assessment of skill acquisition.
Unfractionated Heparin Administered Every 8 h Outperforms 12 Hourly Administration for Venous Thromboembolism Prophylaxis in Reconstructive Head and Neck Tumor Patients: A 12 Year Retrospective Cohort Study
Authors: Cevik Jevan , Newland David P. , Cheong Edward , Shadid Omar , Pang Siyuan , Nagpal Sakshar , Cabalag Miguel , Ramakrishnan Anand
Published: October 2024

Background

Venous thromboembolism (VTE), comprising deep vein thrombosis (DVT) and pulmonary embolism (PE), poses a significant risk of morbidity and mortality in surgical patients, especially those undergoing head and neck cancer surgery with microvascular free flap reconstruction. These patients are at a heightened risk of VTE due to numerous patient and surgical risk factors. VTE chemoprophylaxis guidelines in these patients are limited due to a distinct paucity of research. This study aims to contribute to this scarcity of information, providing guidance for surgeons.

Methods

This retrospective cohort study evaluated the efficacy and safety of subcutaneous unfractionated heparin administered every 8 h versus every 12 h for postoperative VTE prophylaxis in patients undergoing head and neck resections with immediate free flap reconstruction. Data was collected from hospital medical records between January 2010 to December 2021. Patient demographics, operative details, and outcomes, including incidence of VTE and bleeding complications, were analyzed.

Results

Among 622 patients, those receiving heparin every 8 h (n = 393) demonstrated a significantly lower rate of VTE (0.8%) compared to 12‐hourly group (n = 229; 3.9%) (p = 0.006). Additionally, there were no significant differences in the rates of postoperative hematoma between the two groups (9.4% versus 7.9% respectively, p = 0.510).

Conclusion

Our study suggests that an increased daily dose of unfractionated heparin every 8 h for VTE chemoprophylaxis is superior to a 12‐hourly regimen with comparable bleeding profiles. Further multicentre, prospective studies are needed to validate these results and compare the efficacy and safety of unfractionated heparin with other agents such as low‐molecular‐weight heparin in this patient group.
Noise‐assisted hybrid attention networks for low‐dose PET and CT denoising
Authors: Xue Hengzhi , Yao Yudong , Teng Yueyang
Published: October 2024

Background

Positron emission tomography (PET) and computed tomography (CT) play a vital role in tumor‐related medical diagnosis, assessment, and treatment planning. However, full‐dose PET and CT pose the risk of excessive radiation exposure to patients, whereas low‐dose images compromise image quality, impacting subsequent tumor recognition and disease diagnosis.

Purpose

To solve such problems, we propose a Noise‐Assisted Hybrid Attention Network (NAHANet) to reconstruct full‐dose PET and CT images from low‐dose PET (LDPET) and CT (LDCT) images to reduce patient radiation risks while ensuring the performance of subsequent tumor recognition.

Methods

NAHANet contains two branches: the noise feature prediction branch (NFPB) and the cascaded reconstruction branch. Among them, NFPB providing noise features for the cascade reconstruction branch. The cascaded reconstruction branch comprises a shallow feature extraction module and a reconstruction module which contains a series of cascaded noise feature fusion blocks (NFFBs). Among these, the NFFB fuses the features extracted from low‐dose images with the noise features obtained by NFPB to improve the feature extraction capability. To validate the effectiveness of the NAHANet method, we performed experiments using two public available datasets: the Ultra‐low Dose PET Imaging Challenge dataset and Low Dose CT Grand Challenge dataset.

Results

As a result, the proposed NAHANet achieved higher performance on common indicators. For example, on the CT dataset, the PSNR and SSIM indicators were improved by 4.1 dB and 0.06 respectively, and the rMSE indicator was reduced by 5.46 compared with the LDCT; on the PET dataset, the PSNR and SSIM was improved by 3.37 dB and 0.02, and the rMSE was reduced by 9.04 compared with the LDPET.

Conclusions

This paper proposes a transformer‐based denoising algorithm, which utilizes hybrid attention to extract high‐level features of low dose images and fuses noise features to optimize the denoising performance of the network, achieving good performance improvements on low‐dose CT and PET datasets.
Performance evaluation of a small‐animal PET scanner with 213 mm axis using NEMA NU 4‐2008
Authors: Wei Qing , Wang Yingjie , Huang Xianchao , Li Daowu , Zheng Yushuang , Wang Peilin , Sun Xiaoli , Chai Pei , Han Xiaorou , Liu Shuangquan , Feng Baotong , Zhou Wei , Zeng Xiangtao , Zhu Meiling , Zhang Zhiming , Wei Long
Published: October 2024

Background

Long‐axis positron emission tomography (PET) has emerged as one of the recent research directions in PET due to its ability to significantly enhance sensitivity and counting performance for low‐dose imaging, rapid imaging, and whole‐body dynamic imaging.

Purpose

The PET system presented in this study is a long‐axis animal PET based on lutetium–yttrium orthosilicate and silicon photomultiplier, designed for whole‐body imaging in rats. It features a diameter of 143 mm and an axial length of 213.3 mm. This study evaluated the performance of this PET system in accordance with the National Electrical Manufacturers Association (NEMA) NU 4‐2008 standards.

Methods

The performance evaluation was conducted according to the NEMA NU 4‐2008 standards in terms of spatial resolution, sensitivity, counting rate performance, scatter fraction (SF) and image quality. In addition, a rat imaging study was conducted to assess the imaging capability of this PET system.

Results

The average energy resolution of the PET system was 12.87%, the average coincidence timing resolution was 751 ps. The FWHM of spatial resolution reconstructed by filtered back projection and 3D‐OSEM‐PSF algorithm at 5 mm radial offset from the axial center were 1.65 and 0.88 mm. The peak absolute sensitivity measured by a point source at the center of the field of view was evaluated as 6.71% (361–661 keV) and 10.31% (250–750 keV). For the mouse‐like phantom, the SF was 11.0% and the peak noise equivalent counting rate (NECR) was 1193 kcps at 94.2 MBq (2.54 mCi). For the rat‐like phantom, the SF was 26.8% and the NECR was 682.5 kcps at 78.6 MBq (2.12 mCi).

Conclusions

The performance measurement results demonstrate that this PET system exhibits high sensitivity and count rate performance, making it potential for high‐quality whole‐body dynamic imaging of rats.
Necessity and impact of specialization of large foundation model for medical segmentation tasks
Authors: Nguyen Eric , Liu Hengjie , Ruan Dan
Published: October 2024

Background

Large foundation models, such as the Segment Anything Model (SAM), have shown remarkable performance in image segmentation tasks. However, the optimal approach to achieve true utility of these models for domain‐specific applications, such as medical image segmentation, remains an open question. Recent studies have released a medical version of the foundation model MedSAM by training on vast medical data, who promised SOTA medical segmentation. Independent community inspection and dissection is needed.

Purpose

Foundation models are developed for general purposes. On the other hand, stable delivery of reliable performance is key to clinical utility. This study aims at elucidating the potential advantage and limitations of landing the foundation models in clinical use by assessing the performance of off‐the‐shelf medical foundation model MedSAM for the segmentation of anatomical structures in pelvic MR images. We also explore the simple remedies by evaluating the dependency on prompting scheme. Finally, we demonstrate the need and performance gain of further specialized fine‐tuning.

Methods

MedSAM and its lightweight version LiteMedSAM were evaluated out‐of‐the‐box on a public MR dataset consisting of 589 pelvic images split 80:20 for training and testing. An nnU‐Net model was trained from scratch to serve as a benchmark and to provide bounding box prompts for MedSAM. MedSAM was evaluated using different quality bounding boxes, those derived from ground truth labels, those derived from nnU‐Net, and those derived from the former two but with 5‐pixel isometric expansion. Lastly, LiteMedSAM was refined on the training set and reevaluated on this task.

Results

Out‐of‐the‐box MedSAM and LiteMedSAM both performed poorly across the structure set, especially for disjoint or non‐convex structures. Varying prompt with different bounding box inputs had minimal effect. For example, the mean Dice score and mean Hausdorff distances (in mm) for obturator internus using MedSAM and LiteMedSAM were {0.251 ± 0.110, 0.101 ± 0.079} and {34.142 ± 5.196, 33.688 ± 5.306}, respectively. Fine‐tuning of LiteMedSAM led to significant performance gain, improving Dice score and Hausdorff distance for the obturator internus to 0.864 ± 0.123 and 5.022 ± 10.684, on par with nnU‐Net with no significant difference in evaluation of most structures. All segmentation structures benefited significantly from specialized refinement, at varying improvement margin.

Conclusion

While our study alludes to the potential of deep learning models like MedSAM and LiteMedSAM for medical segmentation, it highlights the need for specialized refinement and adjudication. Off‐the‐shelf use of such large foundation models is highly likely to be suboptimal, and specialized fine‐tuning is often necessary to achieve clinical desired accuracy and stability.
Algorithms to reduce the edge effect and improve the flood histogram quality of a PET detector consisting of two pixelated crystal arrays
Authors: Cong Longhan , Kuang Zhonghua , Ren Ning , Sang Ziru , Liu Zheng , Niu Ming , Xie Siwei , Peng Qiyu , Yang Yongfeng
Published: October 2024

Purpose

The performance of detectors is key for a PET scanner to achieve high spatial resolution and high sensitivity. This work aims to develop flood histogram generating algorithms to reduce the edge effect and improve the crystal identification of a PET detector consisting of two optically coupled pixelated scintillator detectors.

Methods

The PET detector consists of two optically coupled detectors, each consisting of a 23×23 LYSO crystal array with a crystal size of 1.0×1.0×20 mm3 read out by an 8×8 SiPM array with a pixel size of 3.0×3.0 mm2. The SiPM array is read out with a resistor network circuit to obtain four position encoding energy signals. A novel center of gravity (COG) positioning algorithm using six signals from the two detectors was proposed and compared to the traditional COG algorithms using either four or eight signals from the detectors. The raised‐to‐the‐power (RTP) method was applied to the three COG algorithms for the PET detector. Different powers of the RTP from 1.0 to 2.5 were evaluated.

Results

The proposed COG algorithm significantly improves the crystal identification at the junction of the two detectors as compared to the COG algorithm using four signals of each detector, and improves the crystal identification at the center of the two detectors as compared to the COG algorithm using eight signals from both detectors. The RTP method significantly improves the overall flood histogram qualities of the two COG algorithms using either eight or six signals from the two detectors, and the two COG algorithm provide similar flood histogram quality when a power of 1.5 is used.

Conclusion

The novel positioning algorithms reduce the edge effect and improve the flood histogram quality for a PET detector consisting of two optically coupled detectors, each consisting of a pixelated scintillator crystal array and a SiPM array with highly multiplexed four signal readout. The positioning algorithms can be used in a PET scanner to improve the spatial resolution and sensitivity.
Single‐shot echo planar time‐resolved imaging for multi‐echo functional MRI and distortion‐free diffusion imaging
Authors: Dong Zijing , Wald Lawrence L. , Polimeni Jonathan R. , Wang Fuyixue
Published: October 2024

Purpose

To develop a single‐shot SNR‐efficient distortion‐free multi‐echo imaging technique for dynamic imaging applications.

Methods

Echo planar time‐resolved imaging (EPTI) was first introduced as a multi‐shot technique for distortion‐free multi‐echo imaging. This work aims to develop single‐shot EPTI (ss‐EPTI) to achieve improved robustness to motion/physiological noise, increased temporal resolution, and higher SNR efficiency. A new spatiotemporal encoding that enables reduced phase‐encoding blips and minimized echo spacing under the single‐shot regime was developed, which improves sampling efficiency and enhances spatiotemporal correlation in the k‐TE space for improved reconstruction. A continuous readout with minimized deadtime was employed to optimize SNR efficiency. Moreover, k‐TE partial Fourier and simultaneous multi‐slice acquisition were integrated for further acceleration.

Results

ss‐EPTI provided distortion‐free imaging with densely sampled multi‐echo images at standard resolutions (e.g., ˜1.25 to 3 mm) in a single‐shot. Improved SNR efficiency was observed in ss‐EPTI due to improved motion/physiological‐noise robustness and efficient continuous readout. Its ability to eliminate dynamic distortions—geometric changes across dynamics due to field changes induced by physiological variations or eddy currents—further improved the data's temporal stability. For multi‐echo fMRI, ss‐EPTI's multi‐echo images recovered signal dropout in short‐ regions and provided TE‐dependent functional information to distinguish non‐BOLD noise for further tSNR improvement. For diffusion MRI, it achieved shortened TEs for improved SNR and provided images free from both B0‐induced and diffusion‐encoding‐dependent eddy‐current‐induced distortions with multi‐TE diffusion metrics.

Conclusion

ss‐EPTI provides SNR‐efficient distortion‐free multi‐echo imaging with comparable temporal resolutions to ss‐EPI, offering a new acquisition tool for dynamic imaging.
First in‐vivo magic angle directional imaging using dedicated low‐field MRI
Authors: Ristic Mihailo , Chappell Karyn E. , Lanz Harry , McGinley John , Gupte Chinmay , Amiras Dimitris
Published: October 2024

Purpose

To report the first in‐vivo results from exploiting the magic angle effect, using a dedicated low‐field MRI scanner that can be rotated about two axes. The magic angle directional imaging (MADI) method is used to depict collagen microstructures with 3D collagen tractography of knee ligaments and the meniscus.

Methods

A novel low‐field MRI system was developed, based on a transverse field open magnet, where the magnet can be rotated about two orthogonal axes. Sets of volume scans at various orientations were obtained in healthy volunteers. The experiments focused on the anterior cruciate ligament (ACL) and the meniscus of the knee. The images were co‐registered, anatomical regions of interest (ROIs) were selected and the collagen fiber orientations in each voxel were estimated from the observed image intensity variations. The 3D collagen tractography was superimposed on conventional volume images.

Results

The MADI method was successfully employed for the first time producing in‐vivo results comparable to those previously reported for excised animal specimens using conventional MRI. Tractography plots were generated for the ACL and the menisci. These results are consistent with the known microstructure of collagen fibers in these tissues.

Conclusion

Images obtained using low‐field MRI with 1 mm3 resolution were of sufficient quality for the MADI method, which was shown to produce high quality in‐vivo information of collagen microstructures. This was achieved using a cost effective and sustainable low‐field magnet making the technique potentially accessible and scalable, potentially changing the way we image injuries or disease in joints.
Age‐specific optimization of the T2‐weighted MRI contrast in infant and toddler brain
Authors: Wu Jiani , Qin Fenjie , Tian Fengyu , Li Haotian , Yong Xingwang , Liu Tingting , Zhang Hongxi , Wu Dan
Published: October 2024

Purpose

In 0–2‐year‐old brains, the T2‐weighted (T2w) contrast between white matter (WM) and gray matter (GM) is weaker compared with that in adult brains and rapidly changes with age. This study aims to design variable‐flip‐angle (VFA) trains in 3D fast spin‐echo sequence that adapt to the dynamically changing relaxation times to improve the contrast in the T2w images of the developing brains.

Methods

T1 and T2 relaxation times in 0–2‐year‐old brains were measured, and several age groups were defined according to the age‐dependent pattern of T2 values. Based on the static pseudo‐steady‐state theory and the extended phase graph algorithm, VFA trains were designed for each age group to maximize WM/GM contrast, constrained by the maximum specific absorption rate and overall signal intensity. The optimized VFA trains were compared with the default one used for adult brains based on the relative contrast between WM and GM. Dice coefficient was used to demonstrate the advantage of contrast‐improved images as inputs for automatic tissue segmentation in infant brains.

Results

The 0–2‐year‐old pool was divided into groups of 0–8 months, 8–12 months, and 12–24 months. The optimal VFA trains were tested in each age group in comparison with the default sequence. Quantitative analyses demonstrated improved relative contrasts in infant and toddler brains by 1.5–2.3‐fold at different ages. The Dice coefficient for contrast‐optimized images was improved compared with default images (p < 0.001).

Conclusion

An effective strategy was proposed to improve the 3D T2w contrast in 0–2‐year‐old brains.
Small Strain Stiffness of Sand‐Rubber Mixtures With Particle Size Disparity Effect
Authors: Liu Deyun , Yin Zhen‐Yu
Published: October 2024

This study systematically investigates the small‐strain stiffness of sand‐rubber mixtures, focusing on combined particle disparity—both larger sand with smaller rubber and smaller sand with larger rubber—using the discrete element method. The effectiveness of various state variables in capturing stiffness behavior across different rubber contents and size disparities (SDs) is evaluated. Conventional state variables developed for natural sands, such as void ratio and mechanical void ratio were found to be less effective in describing the small‐strain stiffness characteristics of sand‐rubber mixtures due to distinct properties of rubber. This study then demonstrates that the stiffness contribution of rubber materials could be negligible, emphasizing that particle property disparity is more significant than SD between sand and rubber materials. Therefore, an adapted state variable, considering only active sand particles, shows improved performance for capturing the correlation between small‐strain stiffness with increasing rubber contents, suggesting its potential utility over conventional variables. Additionally, a refined void ratio, including inactive sand particles but excluding rubber, offers a practical alternative for capturing small‐strain stiffness in experimental and engineering practices, aligning with previous experimental observations. These findings underscore the need for developing more effective state variables that accurately reflect the interactions within heterogeneous materials like sand‐rubber mixtures.
Water Intake in Drinks and Food: How Should We Advise Patients With Lower Urinary Tract Dysfunction on Their Water Intake and/or Urine Output, as a Cornerstone of Lifestyle Interventions? ICI‐RS 2024
Authors: Gammie Andrew , Khullar Vik , Rantell Angie , Cotterill Nikki , Abrams Paul , Song Qi‐Xiang , Smith Matthew , Sinha Sanjay
Published: October 2024

Context

Water intake in drinks and food is essential for life. Multiple guidelines exist to help give recommendations for healthy water intake and urine output, but few of these are specific to patients with lower urinary tract symptoms.

Methods

A debate held at the International Consultation on Incontinence—Research Society meeting, held in Bristol in June 2024, considered ways to improve this situation.

Results and Conclusion

There are challenges in measuring both total water intake and also urine output, but we suggest that urine output may be the most helpful measure to focus on for future guidelines for patients.
Efficacy of Biofeedback Therapy for Giggle Incontinence in Children: How Many Sessions Are Required?
Authors: Canbaz Furkan Adem , Gerçel Gonca , Sağ Sefa
Published: October 2024

Introduction

Giggle incontinence (GI) is characterized by the sudden and involuntary expulsion of urine coinciding with episodes of laughter. The underlying pathophysiology of this condition remains unclear, and various treatment approaches are employed. The objective of this study is to assess the effectiveness of biofeedback (BF) therapy in treating GI and ascertain the requisite number of therapy sessions needed for efficacy.

Methods

Medical records of children treated with BF therapy for GI between November 2022 and November 2023 were retrospectively analyzed. The success of treatment was assessed after four and eight sessions, as well as following three maintenance sessions. Treatment outcomes were evaluated using the scoring system recommended by the International Children's Continence Society (ICCS), which categorizes responses into three levels: no response (Score 0), partial response (Score 1), and complete response (Score 2).

Results

Thirteen patients were initially diagnosed with GI. Of these, 10 patients were included in the study as three discontinued treatments. The cohort comprised an equal gender distribution with five females (50.0%) and five males (50.0%). The mean age of patients was 8.9 ± 3.3 (range 5–16) years. Two out of ten patients had a history of previous treatment for overactive bladder, while three had received treatment for primary monosymptomatic nocturnal enuresis. Following the completion of all BF sessions, the rate of complete response was observed at 80.0% (n = 8), while the partial response rate accounted for 10.0% (n = 1). Statistical analysis revealed significant differences in response scores after four and eight sessions (p < 0.01) as well as between the results after eight sessions and the completion of maintenance sessions (p < 0.01).

Conclusion

BF therapy demonstrates a high success rate in managing GI. Completion of at least eight BF therapy sessions enhances the probability of a successful outcome in the treatment of GI. Additionally, it has been observed that maintenance sessions contribute to the increased efficacy of the treatment.
Graph Regularized Sparse L2,1 Semi‐Nonnegative Matrix Factorization for Data Reduction
Authors: Rhodes Anthony , Jiang Bin , Jiang Jenny
Published: October 2024

Non‐negative Matrix Factorization (NMF) is an effective algorithm for multivariate data analysis, including applications to feature selection, pattern recognition, and computer vision. Its variant, Semi‐Nonnegative Matrix Factorization (SNF), extends the ability of NMF to render parts‐based data representations to include mixed‐sign data. Graph Regularized SNF builds upon this paradigm by adding a graph regularization term to preserve the local geometrical structure of the data space. Despite their successes, SNF‐related algorithms to date still suffer from instability caused by the Frobenius norm due to the effects of outliers and noise. In this paper, we present a new SNF algorithm that utilizes the noise‐insensitive norm. We provide monotonic convergence analysis of the SNF algorithm. In addition, we conduct numerical experiments on three benchmark mixed‐sign datasets as well as several randomized mixed‐sign matrices to demonstrate the performance superiority of SNF over conventional SNF algorithms under the influence of Gaussian noise at different levels.
On some energy‐based variational principles in non‐dissipative magneto‐mechanics using a vector potential approach
Authors: Gebhart Philipp , Wallmersperger Thomas
Published: October 2024

This contribution covers the variational‐based modeling of non‐dissipative magneto‐mechanical systems using a vector potential approach and the thorough analysis and discussion of corresponding conforming finite element methods. Since the construction of divergence‐free finite element spaces explicitly enforcing the Coulomb gauge poses some major challenges, we propose some primal and mixed variational principles that ensure well posedness of the problem and allow to seek the vector potential in unconstrained function spaces. The performance of these methods is assessed in two comparative benchmark studies. The focus of both studies lies on the accurate approximation of field quantities in systems with material discontinuities and re‐entrant corners.
Macroscopic properties of solid oxide fuel cell electrodes via microstructure‐based numerical homogenization
Authors: Langner Eric , Semenov Artem , Makradi Ahmed , Gouttebroze Sylvain , Belouettar Salim , Wallmersperger Thomas
Published: October 2024

Due to climate change, sustainable and energy‐efficient power supply is urgently required. To increase the performance of solid oxide fuel cells, the effects of the microstructure of their porous electrodes need to be studied. Therefore, real tomography images are used to (i) characterize specific geometrical features such as the two‐point correlation function or the tortuosity and (ii) determine the effective conductivities (thermal, ionic, electronic) and the effective permeability. The temperature‐dependent and anisotropic physical properties based on the first‐order homogenization method are described by the dissipation potential. The results can be used in macroscopic fuel cell simulations to bridge the gap between the micro and macro scale and to gain a better understanding of which characteristics of electrode microstructures are favorable for higher efficiency.
Prenatal Diagnosis of Warsaw Breakage Syndrome: Fetal Compound Heterozygous Variants in the DDX11 Gene Associated With Growth Restriction, Cerebral, and Extra‐Cerebral Malformations
Authors: Kratochwila C. , Pomar L. , Lebon S. , Gengler C. , Pavlidou D. C. , Good J.‐M. , Kumps C. , Sichitiu J.
Published: October 2024

Warsaw Breakage Syndrome (WABS) is a rare autosomal recessive cohesinopathy characterized by growth retardation and congenital anomalies. This report aims to highlight the prenatal diagnosis of WABS through ultrasound findings and genetic testing. We report a case of prenatal diagnosis of WABS in a 24‐week gestation fetus exhibiting microcephaly, delayed sulcation, short corpus callosum, cerebellar vermis hypoplasia and intrahepatic portal‐systemic shunts. The couple had a history of a prior pregnancy termination due to severe intrauterine growth restriction and cerebral malformations. Whole exome sequencing revealed compound heterozygous pathogenic variants [NM_030653.4:c.1403dupT, p.(Ser469Valfs*32) and c.1672C>T, p.(Arg558*)] in the DDX11 gene, consistent with WABS. The same pathogenic variants were identified in the prior terminated fetus upon subsequent analysis. Postmortem examination of the proband confirmed the prenatal ultrasound findings. This case expands the understanding of the prenatal phenotypic spectrum of WABS by identifying specific cerebral and extracerebral anomalies associated with pathogenic variants in the DDX11 gene. Incorporating advanced genetic diagnostics like whole exome sequencing into prenatal care provides valuable information for genetic counseling and management of rare genetic disorders.
Integrative physiological and transcriptome analysis unravels the mechanism of low nitrogen use efficiency in burley tobacco
Authors: Feng Yuqing , Zhao Yuanyuan , Ma Yanjun , Chen Xiaolong , Shi Hongzhi
Published: October 2024

Burley tobacco, a chlorophyll‐deficient mutant with impaired nitrogen use efficiency (NUE), generally requires three to five times more nitrogen fertilization than flue‐cured tobacco to achieve a comparable yield, which generates serious environmental pollution and negatively affects human health. Therefore, exploring the mechanisms underlying NUE is an effective measure to reduce environmental pollution and an essential direction for burley tobacco plant improvement. Physiological and genetic factors affecting tobacco NUE were identified using two tobacco genotypes with contrasting NUE in hydroponic experiments. Nitrogen use inefficient genotype (TN90) had lower nitrogen uptake and transport efficiencies, reduced leaf and root biomass, lower nitrogen assimilation and photosynthesis capacity, and lower nitrogen remobilization ability than the nitrogen use efficient genotype (K326). Transcriptomic analysis revealed that genes associated with photosynthesis, carbon fixation, and nitrogen metabolism are implicated in NUE. Three nitrate transporter genes in the leaves (NPF2.11, NPF2.13, and NPF3.1) and three nitrate transporter genes (NPF6.3, NRT2.1, and NRT2.4) in roots were down‐regulated by nitrogen starvation, all of which showed lower expression in TN90 than in K326. In addition, the protein–protein interaction (PPI) network diagram identified eight key genes (TPIP1, GAPB, HEMB, PGK3, PSBO, PSBP2, PSAG, and GLN2) that may affect NUE. Less advantageous changes in nitrogen uptake, nitrogen assimilation in combination with nitrogen remobilization, and maintenance of photosynthesis in response to nitrogen deficiency led to a lower NUE in TN90. The key genes (TPIP1, GAPB, PGK3, PSBO, PSBP2, PSAG, and GLN2) were associated with improving photosynthesis and nitrogen metabolism in tobacco plants grown under N‐deficient conditions.