bluuebunny/crossref_metadata_2025 huggingface dataset:
Type-C Simulations of Centrifuge Tests from LEAP-ASIA-2019 Using SANISAND-Sf
Authors: Reyes Andrés , Barrero Andrés R. , Taiebat Mahdi
Published: February 2024

This chapter presents Type-C numerical simulations of prototype-scale centrifuge tests on gently sloped liquefiable deposits of Ottawa F65 sand for the LEAP-ASIA-2019 project. The simulations aim to assess the performance of the numerical modeling approach and a SANISAND-type constitutive model for large post-liquefaction shear deformation of sands. The constitutive model is calibrated against cyclic torsional shear tests conducted at different relative density levels and cyclic shear stress amplitudes. The laboratory-determined hydraulic conductivity of sand is doubled and kept constant during the dynamic stage of the analyses to account for the increase in permeability experienced during liquefaction. The simulations successfully capture the acceleration response and excess pore water pressure generation and dissipation of the slope deposit when soil liquefaction is observed. However, accurately modeling lateral displacements remains challenging in most cases. The results provide insights into the capabilities and limitations of the adopted Type-C numerical simulations, numerical modeling approach, and constitutive model.
LEAP-ASIA-2019 Numerical Simulations Using a Strain Space Multiple Mechanism Model for a Liquefiable Sloping Ground
Authors: Tanaka Yoshikazu , Sahare Anurag , Ueda Kyohei , Yuyama Waka , Iai Susumu
Published: February 2024

This chapter presents the numerical simulations using a strain space multiple mechanism model on a liquefiable sloping ground during earthquake excitation which are compared with the results obtained from the centrifuge tests conducted at different centrifuge facilities as a part of LEAP-ASIA-2019 with an effort to validate the generalized scaling laws. The constitutive model parameters were determined based on the results of cyclic torsional shear tests. One of the key objectives of this chapter is to assess the differences arising in the soil system responses depending on the three different predictors when using the same constitutive model. For this purpose, the soil constitutive model parameters were calibrated differently, and all the predictors were able to capture the important features of saturated sand during undrained cyclic shearing. This was followed by the numerical simulations of the centrifuge data, which showed no predominant differences in the simulated results due to the different soil constitutive model parameters. However, the amount of shear-induced dilatancy experienced by the sand during cyclic shearing was found out to be different among predictors. It is also highlighted that predictors may achieve the ideal measured results either by performing numerical simulations in model scale or in prototype scale.
LEAP-ASIA-2019 Centrifuge Test Simulation at UNINA
Authors: Fasano Gianluca , Chiaradonna Anna , Bilotta Emilio
Published: February 2024

This chapter describes the numerical simulations carried out at the University of Napoli Federico II in the framework of the LEAP-ASIA-2019 Simulation Exercise. An advanced critical state compatible, bounding surface plasticity model for sand has been adopted and calibrated on the available cyclic laboratory test data. The calibration has been finalized to catch the cyclic strength of the investigated sand. Centrifuge test simulations have been performed by means of the finite element code PLAXIS, which is a commercial code well widespread in the community of geotechnical practitioners. Type-C simulations highlighted the capability of the numerical model to reasonably predict the time histories of acceleration and excess pore water pressure measured during the experimental tests.
LEAP-ASIA-2019 Centrifuge Test Simulations of Liquefiable Sloping Ground
Authors: Qiu Zhijian , Elgamal Ahmed
Published: February 2024

Numerical simulations of a liquefiable sloping ground for LEAP-ASIA-2019 centrifuge tests are presented. The simulations are performed using a pressure-dependent constitutive model implemented with the characteristics of dilatancy, cyclic mobility, and associated shear deformation. The soil model parameters are determined based on a series of stress-controlled cyclic torsional shear tests of Ottawa F-65 sand with relative density Dr = 60% during calibration phase. Computational framework for the seismic response analysis is discussed and the computed results are presented for all selected centrifuge experiments during Type-C phase. Measured time histories of these experiments are reasonably captured. It is demonstrated that the pressure-dependent constitutive model as well as the overall employed computational framework has the potential to predict the response of the liquefiable sloping ground, and subsequently realistically evaluates the performance of an equivalent soil system subjected to seismically induced liquefaction.
LEAP-ASIA-2019 Simulations at Tsinghua University
Authors: Wang Rui , Zhu Tong , Zhou Chuang , Zhang Jian-Min
Published: February 2024

This chapter presents the constitutive model calibration and numerical simulations of centrifuge shaking table tests for LEAP-ASIA-2019, at Tsinghua University. A plasticity model that can provide unified description for the behavior sand at different states under both monotonic and cyclic loading, with focus on the large post-liquefaction shear deformation, is calibrated and used in this study. New undrained cyclic torsional shear test results for Ottawa F65 sand provided in the most recent phase of the LEAP project are used in the calibration process. Typical results for acceleration, excess pore pressure, and displacement for one of the tests are presented in detail, showing that the numerical simulation is able to capture the liquefaction related behavior in the tests well. Comparisons between the simulation and test residual displacement results for the five different tests show conflicting results. The simulations for the two RPI tests under different centrifuge acceleration levels with different stress states and input motion frequencies generally show adequate agreement with test results, exhibiting the constitutive model and numerical simulation method’s wide applicability range. However, the simulation results for the KyU tests are significantly different to the test results.
Dynamic Torsional Shear Tests of Ottawa F-65 Sand for LEAP-ASIA-2019
Authors: Vargas Ruben R. , Ueda Kyohei , Uemura Kazuaki
Published: February 2024

The Liquefaction Experiments and Analysis Projects (LEAP) is an international collaborative project that aims to verify, validate, and quantify the uncertainty of numerical liquefaction models. Within this project, a series of hollow cylinder cyclic torsional shear tests were performed at the Disaster Prevention Research Institute facility at Kyoto University. These tests focused on examining how the relative density affects the cyclic response of Ottawa F-65 sand. The obtained results will contribute to a dependable database for the ongoing and future verification and validation processes of liquefaction models. This paper presents the details of the model preparation and test results, as well as a brief discussion on the influence of the relative density and the tests’ repeatability.
LEAP-ASIA-2019 Centrifuge Test at KAIST
Authors: Manandhar Satish , Kim Seong-Nam , Kim Dong-Soo
Published: February 2024

Since Niigata and Alaska earthquakes in 1964, the dangers of liquefaction are well established, and research into liquefaction has been actively performed. In this context, Liquefaction Experiments and Analysis Projects (LEAP) was launched to provide high-quality experimental data on soil liquefaction using laboratory testing and centrifuge modeling and then validating numerical models to improve predictions. The purpose of LEAP-ASIA-2019, which is one of the LEAP programs, was to fill the gaps and further extend/establish/confirm the trends obtained in the previous LEAP-UCD-2017 program. Further, the validity of the generalized scaling law was also tested for liquefaction simulation using different 1-g and centrifuge scaling factors. During LEAP-ASIA-2019, KAIST performed two model tests (Model A and Model B) with the same target relative density (Dr = 85%) and input motion intensity of 0.3g. Models A and B were identical in construction but were tested under different centrifugal accelerations to verify the generalized scaling factors. This paper describes the experimental procedure in detail and the responses of dense model grounds to strong base shaking in terms of ground accelerations, excess pore pressure, surface displacements, stress-strain behavior, and CPT profiles. Further, discussion on the generalized scaling law and the effect of shaking history on the model behavior are also presented.
Global conformal blocks via shadow formalism
Authors: Belavin Vladimir , Cabezas J. Ramos
Published: February 2024

Abstract

We study 𝔰𝔩2 and 𝔰𝔩3 global conformal blocks on a sphere and a torus, using the shadow formalism. These blocks arise in the context of Virasoro and 𝒲3 conformal field theories in the large central charge limit. In the 𝔰𝔩2 case, we demonstrate that the shadow formalism yields the known expressions in terms of conformal partial waves. Then, we extend this approach to the 𝔰𝔩3 case and show that it allows to build simple integral representations for 𝔰𝔩3 global blocks. We demonstrate this construction on two examples: the four-point block on the sphere and the one-point torus block.
Endonasal-endoskopische anteriore Schädelbasischirurgie
Authors: Schmitz Lisa , Betz Christian S. , Stölzel Katharina
Published: February 2024

Hintergrund

Die erweiterte endonasal-endoskopische Chirurgie („extended endoscopic endonasal surgery“, EEES) ist ein wesentlicher Bestandteil der Behandlung diverser pathologischer Veränderungen der vorderen Schädelbasis. Neben einer deutlichen Steigerung der Lebensqualität der betroffenen Patiente:innen und einem geringeren Komplikationsprofil als bei der offenen Schädelbasischirurgie sind die therapeutischen Ergebnisse bei richtiger Indikationsstellung vergleichbar.

Material und Methoden

Es erfolgte eine retrospektive Datenerhebung aller endonasal-endoskopischen Schädelbasiseingriffe, die im Zeitraum von Juni 2018 bis November 2022 am universitären Schädelbasiszentrum Hamburg unter Führung der Klinik für Hals‑, Nasen- und Ohrenheilkunde durchgeführt wurden.

Ergebnisse

Insgesamt 50 Fälle wurden identifiziert. Dabei handelte es sich in 56 % (28/50) um maligne Tumoren, in 24 % (12/50) um benigne pathologische Veränderungen mit direkter Schädelbasisbeteiligung sowie in 20 % (10/50) um anteriore Schädelbasisdefekte mit Rhinoliquorrhö. In 94 % (47/50) der Fälle konnte das präoperativ gesteckte Ziel des Eingriffs (repräsentative Biopsie, vollständige Resektion, Verschluss des Schädelbasisdefekts) erreicht werden. Komplikationen vom Grad III oder höher nach Clavien-Dindo traten in 4/50 Fällen auf. Im Beobachtungszeitraum wurden n = 5 Olfaktoriusneuroblastome diagnostiziert, von denen alle ausschließlich und erfolgreich endoskopisch operiert wurden.

Schlussfolgerung

In den vergangenen Jahren hat sich das Spektrum der endoskopisch resezierbaren pathologischen Veränderungen der anterioren Schädelbasis stetig erweitert. Insbesondere mittellinienbezogene Tumoren wie das Olfaktoriusneuroblastom oder iatrogene/idiopathische Schädelbasisdefekte mit Liquorrhö werden mit sehr guten Ergebnissen vollständig endoskopisch therapiert. Nichtsdestotrotz ergeben sich auch Limitationen für diese Technik. Aufgrund der hohen Varianz des Umfangs frontobasaler Eingriffe, der Ausdehnung und der komplexen Anatomie sowie der sich überschneidenden Zuständigkeiten der Fachdisziplinen ist die Etablierung von zertifizierten Schädelbasiszentren und die Bündelung der frontobasalen Chirurgie an diesen Zentren von hoher Relevanz für die Qualitätssicherung.
A novel step-by-step procedure for the kinematic calibration of robots using a single draw-wire encoder
Authors: Boschetti Giovanni , Sinico Teresa
Published: February 2024

Robot positioning accuracy is a key factory when performing high-precision manufacturing tasks. To effectively improve the accuracy of a manipulator, often up to a value close to its repeatability, calibration plays a crucial role. In the literature, various approaches to robot calibration have been proposed, and they range considerably in the type of measurement system and identification algorithm used. Our aim was to develop a novel step-by-step kinematic calibration procedure — where the parameters are subsequently estimated one at a time — that only uses 1D distance measurement data obtained through a draw-wire encoder. To pursue this objective, we derived an analytical approach to find, for each unknown parameter, a set of calibration points where the discrepancy between the measured and predicted distances only depends on that unknown parameter. This reduces the computational burden of the identification process while potentially improving its accuracy. Simulations and experimental tests were carried out on a 6 degrees-of-freedom robot arm: the results confirmed the validity of the proposed strategy. As a result, the proposed step-by-step calibration approach represents a practical, cost-effective and computationally less demanding alternative to standard calibration approaches, making robot calibration more accessible and easier to perform.
Supercritical melt flow in high-speed laser welding and its interdependence with the geometry of the keyhole and the melt pool
Authors: Reinheimer Eveline N. , Berger Peter , Hagenlocher Christian , Weber Rudolf , Graf Thomas
Published: February 2024

The advent of undercuts and humping limits the applicable speed of deep-penetration laser welding. Recent findings additionally show that a significant change of the keyhole’s shape is associated with the occurrence of undercuts. Considering that undercuts and humping are melt flow–induced defects, this leads to the question of how the geometry of the keyhole and the melt pool influence the melt flow and vice versa. In this work, the Froude number was used to characterize the melt flow around a keyhole. X-ray images of the keyhole and cross-sections of the weld were therefore used to determine the geometrical boundaries of the melt flow, to estimate the average melt velocity around the keyhole, and finally determine its Froude number. The flow around a cylindrically shaped keyhole was found to always be subcritical, whereas supercritical melt flow was observed around the elongated keyholes that are formed at higher welding speed. The findings may be interpreted in the sense that the elongation of the keyhole is a consequence of a supercritical stream of the melt flowing underneath and around the keyhole. This perception is consistent with the long-known experience that humping may be avoided by reducing the flow speed of the melt by widening the melt pool surrounding the keyhole (e.g., by means of beam shaping) and suggest a new explanation for the elongation of the keyhole at increased welding speed.
Nash implementation of supermajority rules
Authors: Amorós Pablo
Published: February 2024

A committee of n experts from a university department must choose whom to hire from a set of m candidates. Their honest judgments about the best candidate must be aggregated to determine the socially optimal candidates. However, experts’ judgments are not verifiable. Furthermore, the judgment of each expert does not necessarily determine his preferences over candidates. To solve this problem, a mechanism that implements the socially optimal aggregation rule must be designed. We show that the smallest quota q compatible with the existence of a q-supermajoritarian and Nash implementable aggregation rule is $$q=n-\left\lfloor \frac{n-1}{m}\right\rfloor$$

q
=
n
-

n
-
1

m

. Moreover, for such a rule to exist, there must be at least $$m\left\lfloor \frac{n-1}{m}\right\rfloor +1$$

m

n
-
1

m

+
1

impartial experts with respect to each pair of candidates.
Impact of Mannitol Bladder Distension in the Intraoperative Detection of Ureteral Kinking During Pelvic Floor Surgery
Authors: Barba Marta , Cola Alice , Costa Clarissa , Frigerio Matteo
Published: February 2024

Introduction and Hypothesis

Ureteral injuries are the most feared complications of gynecological surgery and therefore intraoperative recognition is of the utmost importance. Intraoperative cystoscopy represents the diagnostics of choice to investigate ureteral patency thanks to the direct visualization of ureteral flows after administration of infusion mediums. In this study, we aimed to compare the diagnostic performance of saline versus mannitol intraoperative cystoscopy in terms of false negatives in a large cohort of patients.

Methods

We retrospectively analyzed data of patients who underwent vaginal hysterectomy and high uterosacral ligament suspension for POP. Patients were divided in two groups based on the use of saline or mannitol medium for intraoperative cystoscopy. Postoperative daily control of serum creatinine was performed until discharge, as well as urinary tract imaging, in symptomatic patients.

Results

A total of 925 patients underwent vaginal hysterectomy followed by high USL suspension for POP. Saline and mannitol medium were used in 545 patients and 380 patients respectively. Postoperative ureteral injuries were identified in 12 patients, specifically in 2% of the saline group and in 0.3% of the mannitol group.

Conclusions

The use of mannitol instead of saline as a bladder distension medium was able to significantly reduce the occurrence of postoperative ureteral sequelae.
Complexity of the (Connected) Cluster Vertex Deletion Problem on H-free Graphs
Authors: Le Hoang-Oanh , Le Van Bang
Published: February 2024

The well-known Cluster Vertex Deletion problem (cluster-vd) asks for a given graph G and an integer k whether it is possible to delete a set S of at most k vertices of G such that the resulting graph $$G-S$$

G
-
S

is a cluster graph (a disjoint union of cliques). We give a complete characterization of graphs H for which cluster-vd on H-free graphs is polynomially solvable and for which it is $$\textsf{NP}$$
NP
-complete. Moreover, in the $$\textsf{NP}$$
NP
-completeness cases, cluster-vd cannot be solved in sub-exponential time in the vertex number of the H-free input graphs unless the Exponential-Time Hypothesis fails. We also consider the connected variant of cluster-vd, the Connected Cluster Vertex Deletion problem (connected cluster-vd), in which the set S has to induce a connected subgraph of G. It turns out that connected cluster-vd admits the same complexity dichotomy for H-free graphs. Our results enlarge a list of rare dichotomy theorems for well-studied problems on H-free graphs.
The foraging ecology of green turtles (Chelonia mydas) in New Caledonia
Authors: Read Tyffen C. , Wantiez Laurent , Keller Florent , Werry Jonathan M. , van de Merwe Jason P. , Meager Justin J. , Chateau Olivier , Farman Richard , Limpus Colin J.
Published: February 2024

Green sea turtles (Chelonia mydas) face many threats from anthropogenic activity and are listed as Endangered on the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species. They spend the majority of their lives in coastal foraging areas, and show strong fidelity to narrow foraging ranges. Understanding the foraging ecology of green turtles is therefore important for their management and conservation. Using stable isotopes analysis (n = 200) and identification of stomach contents (n = 21), this study investigated the foraging ecology of four distinct green turtle foraging aggregations (Goro, Isle of Pines, Ouen Island and Uo/Mato Islands) within the Grand Lagon Sud. This World Heritage Area located in New Caledonia supports regionally important nesting and foraging green turtle populations. The δ13C and δ15N values of skin samples ranged from − 19.3 to  − 7.3‰ and 2.8–15.9‰, respectively. Metrics of isotopic niche and regression analyses were used to assess the degree of omnivory, trophic diversity and potential ontogenetic diet shifts in the different aggregations of foraging green turtles in this location. Each of the four sites and four age-classes had distinct isotopic niches, with evidence of omnivory and ontogenetic shifts, particular in new recruits and juveniles, and at Goro and Uo/Mato Islands. This was generally supported by the stomach contents analyses of a small number of green turtles opportunistically sampled from traditional ceremonies. This study provides important information on the foraging ecology of green turtles in New Caledonia, supporting management outcomes in this region. This collaboration with the tribes of the Grand Lagon Sud is also the first step towards the integrated management of the resource.
Dose-dependent effect of lamotrigine on quetiapine serum concentration in patients using instant release tablets
Authors: Hole Kristine , Lorentsen Silje K , Nordby Karoline L , Slettvik Marie , Sørum Ida TG , Molden Espen , Haslemo Tore
Published: February 2024

Purpose

Lamotrigine was previously reported to reduce serum concentration of quetiapine. The aim of this study was to investigate whether lamotrigine dose or quetiapine formulation was of importance for the drug interaction.

Methods

Patients combining lamotrigine with quetiapine (cases) were included retrospectively from a routine therapeutic drug monitoring (TDM) service, as were a control group of patients using quetiapine without any interacting drugs. The case and control groups were divided into groups using immediate release (IR) and extended release (XR) quetiapine. The case group was further split into high-dose (> 200 mg/day) and low-dose (≤ 200 mg/day) lamotrigine users. Quetiapine concentration-to-dose (C/D) ratio and metabolite-to-parent ratio (MPR) were compared between the control group and dose-separated case groups using ANOVA test and t-tests.

Results

In total, 406 patients were included. The mean C/D ratio of IR quetiapine was 46% lower in the high-dose lamotrigine group compared with the control group (P < 0.001), while no interaction effect was present in the low dose lamotrigine group (P = 0.7). Regardless of lamotrigine dose, there was no difference in quetiapine C/D ratio for patients using the XR formulation (P = 0.4). The quetiapine MPR was unaffected regardless of formulation and lamotrigine dose (P ≥ 0.06).

Conclusion

The effect of lamotrigine in reducing quetiapine concentration is only significant for patients using quetiapine IR tablets who are treated with lamotrigine doses > 200 mg/day. Because of high variability in the interaction effect, TDM of quetiapine should be recommended during co-prescription of high-dose lamotrigine.
Dissipativity in Infinite Horizon Optimal Control and Dynamic Programming
Authors: Angeli David , Grüne Lars
Published: February 2024

In this paper we extend dynamic programming techniques to the study of discrete-time infinite horizon optimal control problems on compact control invariant sets with state-independent best asymptotic average cost. To this end we analyse the interplay of dissipativity and optimal control, and propose novel recursive approaches for the solution of so called shifted Bellman Equations.
Construction of viral-based expression vectors for high-level production of human interferon alpha 2b in plants
Authors: Sindarovska Yana , Kuchuk Mykola
Published: February 2024

Human interferon (hINF) alpha 2b is clinically important pharmaceutical product included in combinatory therapy against chronic hepatitis C and B and complex therapy against several cancer diseases. Here, we created the genetic constructions, based on genome elements of potato virus X (PVX), carrying the infα2b gene for transient expression in plant cells. The created plasmid vector constructions were tested through Agrobacterium-mediated transient gene expression method in two plant species—Nicotiana benthamiana and Ocimum basilicum (sweet basil). Production of recombinant hINF alpha 2b was more efficient in N. benthamiana than that in O. basilicum plants. The average yield of hINF alpha 2b produced in N. benthamiana plants was 0.56 mg/g of fresh leaf weight (FW) or 6% of the total soluble cell proteins (TSP). The maximal level reached up to 1.2 mg/g FW or 9% TSP. We estimated that about 0.67 mg of hINF can be obtained from one N. benthamiana plant. The yield of hINF alpha 2b obtained with the PVX-based expression cassette was about 80 times higher than the yield of hINF alpha 2b obtained with a simple expression cassette in which the infα2b gene was controlled by the 35S promoter of cauliflower mosaic virus.

Key points

• PVX-based expression vectors provide efficient transient expression of infα2b gene

• N. benthamiana plants can produce human interferon alpha 2b at high levels

• The yield of the hINF α2b reached up to 1.2 mg/g of fresh leaf weight
A new and promiscuous α/β hydrolase from Acinetobacter tandoii DSM 14970 T inactivates the mycotoxin ochratoxin A
Authors: Sánchez-Arroyo Ana , Plaza-Vinuesa Laura , Abeijón-Mukdsi María Claudia , de las Rivas Blanca , Mancheño José Miguel , Muñoz Rosario
Published: February 2024

The presence of ochratoxin A (OTA) in food and feed represents a serious concern since it raises severe health implications. Bacterial strains of the Acinetobacter genus hydrolyse the amide bond of OTA yielding non-toxic OTα and L-β-phenylalanine; in particular, the carboxypeptidase PJ15_1540 from Acinetobacter sp. neg1 has been identified as an OTA-degrading enzyme. Here, we describe the ability to transform OTA of cell-free protein extracts from Acinetobacter tandoii DSM 14970 T, a strain isolated from sludge plants, and also report on the finding of a new and promiscuous α/β hydrolase (ABH), with close homologs highly distributed within the Acinetobacter genus. ABH from A. tandoii (AtABH) exhibited amidase activity against OTA and OTB mycotoxins, as well as against several carboxypeptidase substrates. The predicted structure of AtABH reveals an α/β hydrolase core composed of a parallel, six-stranded β-sheet, with a large cap domain similar to the marine esterase EprEst. Further biochemical analyses of AtABH reveal that it is an efficient esterase with a similar specificity profile as EprEst. Molecular docking studies rendered a consistent OTA-binding mode. We proposed a potential procedure for preparing new OTA-degrading enzymes starting from promiscuous α/β hydrolases based on our results.

Key points

• AtABH is a promiscuous αβ hydrolase with both esterase and amidohydrolase activities

• AtABH hydrolyses the amide bond of ochratoxin A rendering nontoxic OTα

• Promiscuous αβ hydrolases are a possible source of new OTA-degrading enzymes
EANM practice guidelines for an appropriate use of PET and SPECT for patients with epilepsy
Authors: Traub-Weidinger Tatjana , Arbizu Javier , Barthel Henryk , Boellaard Ronald , Borgwardt Lise , Brendel Matthias , Cecchin Diego , Chassoux Francine , Fraioli Francesco , Garibotto Valentina , Guedj Eric , Hammers Alexander , Law Ian , Morbelli Silvia , Tolboom Nelleke , Van Weehaeghe Donatienne , Verger Antoine , Van Paesschen Wim , von Oertzen Tim J. , Zucchetta Pietro , Semah Franck
Published: February 2024

Epilepsy is one of the most frequent neurological conditions with an estimated prevalence of more than 50 million people worldwide and an annual incidence of two million. Although pharmacotherapy with anti-seizure medication (ASM) is the treatment of choice, ~30% of patients with epilepsy do not respond to ASM and become drug resistant. Focal epilepsy is the most frequent form of epilepsy. In patients with drug-resistant focal epilepsy, epilepsy surgery is a treatment option depending on the localisation of the seizure focus for seizure relief or seizure freedom with consecutive improvement in quality of life. Beside examinations such as scalp video/electroencephalography (EEG) telemetry, structural, and functional magnetic resonance imaging (MRI), which are primary standard tools for the diagnostic work-up and therapy management of epilepsy patients, molecular neuroimaging using different radiopharmaceuticals with single-photon emission computed tomography (SPECT) and positron emission tomography (PET) influences and impacts on therapy decisions. To date, there are no literature-based praxis recommendations for the use of Nuclear Medicine (NM) imaging procedures in epilepsy. The aims of these guidelines are to assist in understanding the role and challenges of radiotracer imaging for epilepsy; to provide practical information for performing different molecular imaging procedures for epilepsy; and to provide an algorithm for selecting the most appropriate imaging procedures in specific clinical situations based on current literature. These guidelines are written and authorized by the European Association of Nuclear Medicine (EANM) to promote optimal epilepsy imaging, especially in the presurgical setting in children, adolescents, and adults with focal epilepsy. They will assist NM healthcare professionals and also specialists such as Neurologists, Neurophysiologists, Neurosurgeons, Psychiatrists, Psychologists, and others involved in epilepsy management in the detection and interpretation of epileptic seizure onset zone (SOZ) for further treatment decision. The information provided should be applied according to local laws and regulations as well as the availability of various radiopharmaceuticals and imaging modalities.
Utilizing fully-automated 3D organ segmentation for hepatic steatosis assessment with CT attenuation-based parameters
Authors: Yoo Jeongin , Joo Ijin , Jeon Sun Kyung , Park Junghoan , Yoon Soon Ho
Published: February 2024

Objectives

To investigate the clinical utility of fully-automated 3D organ segmentation in assessing hepatic steatosis on pre-contrast and post-contrast CT images using magnetic resonance spectroscopy (MRS)-proton density fat fraction (PDFF) as reference standard.

Materials and methods

This retrospective study analyzed 362 adult potential living liver donors with abdominal CT scans and MRS-PDFF. Using a deep learning-based tool, mean volumetric CT attenuation of the liver and spleen were measured on pre-contrast (liver(L)_pre and spleen(S)_pre) and post-contrast (L_post and S_post) images. Agreements between volumetric and manual region-of-interest (ROI)-based measurements were assessed using the intraclass correlation coefficient (ICC) and Bland–Altman analysis. Diagnostic performances of volumetric parameters (L_pre, liver-minus-spleen (L-S)_pre, L_post, and L-S_post) were evaluated for detecting MRS-PDFF ≥ 5% and ≥ 10% using receiver operating characteristic (ROC) curve analysis and compared with those of ROI-based parameters.

Results

Among the 362 subjects, 105 and 35 had hepatic steatosis with MRS-PDFF ≥ 5% and ≥ 10%, respectively. Volumetric and ROI-based measurements revealed ICCs of 0.974, 0.825, 0.992, and 0.962, with mean differences of −4.2 HU, −3.4 HU, −1.2 HU, and −7.7 HU for L_pre, S_pre, L_post, and S_post, respectively. Volumetric L_pre, L-S_pre, L_post, and L-S_post yielded areas under the ROC curve of 0.813, 0.813, 0.734, and 0.817 for MRS-PDFF ≥ 5%; and 0.901, 0.915, 0.818, and 0.868 for MRS-PDFF ≥ 10%, comparable with those of ROI-based parameters (0.735–0.818; and 0.816–0.895, Ps = 0.228–0.911).

Conclusion

Automated 3D segmentation of the liver and spleen in CT scans can provide volumetric CT attenuation-based parameters to detect and grade hepatic steatosis, applicable to pre-contrast and post-contrast images.

Clinical relevance statement

Volumetric CT attenuation-based parameters of the liver and spleen, obtained through automated segmentation tools from pre-contrast or post-contrast CT scans, can efficiently detect and grade hepatic steatosis, making them applicable for large population data collection.

Key Points

• Automated organ segmentation enables the extraction of CT attenuation-based parameters for the target organ.

• Volumetric liver and spleen CT attenuation-based parameters are highly accurate in hepatic steatosis assessment.

• Automated CT measurements from pre- or post-contrast imaging show promise for hepatic steatosis screening in large cohorts.

Graphical abstract
One-year clinical outcomes of MR-guided stereotactic body radiation therapy with rectal spacer for patients with localized prostate cancer
Authors: Poon Darren M. C. , Yuan Jing , Wong Oi Lei , Yang Bin , Tse Mei Yan , Lau Ka Ki , Chiu Sin Ting , Chiu Peter Ka-Fung , Ng Chi Fai , Chui Ka Lun , Kwong Yiu Ming , Ma Wai Kit , Cheung Kin Yin , Chiu George , Yu Siu Ki
Published: February 2024

Background and purpose

This prospective study aimed to investigate adaptive magnetic resonance (MR)-guided stereotactic body radiation therapy (MRgSBRT) with rectal spacer for localized prostate cancer (PC) and report 1-year clinical outcomes.

Materials and methods

Thirty-four consecutive patients with low- to high-risk localized PC that underwent 5-fraction adaptive MRgSBRT with rectal spacer were enrolled. The dosimetric comparison was performed on a risk- and age-matched cohort treated with MRgSBRT but without a spacer at a similar timepoint. Clinician-reported outcomes were based on Common Terminology Criteria for Adverse Events. Patient-reported outcomes were based on the Expanded Prostate Cancer Index Composite (EPIC) questionnaire at baseline, acute (1–3 months), subacute (4–12 months), and late (> 12 months) phases.

Results

The median follow-up was 390 days (range 28–823) and the median age was 70 years (range 58–82). One patient experienced rectal bleeding soon after spacer insertion that subsided before MRgSBRT. The median distance between the midline of the prostate midgland and the rectum after spacer insertion measured 7.8 mm (range 2.6–15.3), and the median length of the spacer was 45.9 mm (range 16.8–62.9) based on T2-weighted MR imaging. The use of spacer resulted in significant improvements in target coverage (V100% > 95% = 98.6% [range 93.4–99.8] for spacer vs. 97.8% [range 69.6–99.7] for non-spacer) and rectal sparing (V95% < 3 cc = 0.7 cc [range 0–4.6] for spacer vs. 4.9 cc [range 0–12.5] for non-spacer). Nine patients (26.5%) experienced grade 1 gastrointestinal toxicities, and no grade ≥ 2 toxicities were observed. During the 1-year follow-up period, EPIC scores for the bowel domain remained stable and were the highest among all other domains.

Conclusions

MRgSBRT with rectal spacer for localized PC showed exceptional tolerability with minimal gastrointestinal toxicities and satisfactory patient-reported outcomes. Improvements in dosimetry, rectal sparing, and target coverage were achieved with a rectal spacer. Randomized trials are warranted for further validation.
WaveNets: physics-informed neural networks for full-field recovery of rotational flow beneath large-amplitude periodic water waves
Authors: Chen Lin , Li Ben , Luo Chenyi , Lei Xiaoming
Published: February 2024

We formulate physics-informed neural networks (PINNs) for full-field reconstruction of rotational flow beneath nonlinear periodic water waves using a small amount of measurement data, coined WaveNets. The WaveNets have two NNs to, respectively, predict the water surface, and velocity/pressure fields. The Euler equation and other prior knowledge of the wave problem are included in WaveNets loss function. We also propose a novel method to dynamically update the sampling points in residual evaluation as the free surface is gradually formed during model training. High-fidelity data sets are obtained using the numerical continuation method which is able to solve nonlinear waves close to the largest height. Model training and validation results in cases of both one-layer and two-layer rotational flows show that WaveNets can reconstruct wave surface and flow field with few data either on the surface or in the flow. Accuracy in vorticity estimate can be improved by adding a redundant physical constraint according to the prior information on the vorticity distribution.
Use of Vitex agnus-castus in patients with menstrual cycle disorders: a single-center retrospective longitudinal cohort study
Authors: Höller Martina , Steindl Hubert , Abramov-Sommariva Dimitri , Kleemann Julia , Loleit Alexey , Abels Christoph , Stute Petra
Published: February 2024

Purpose

To evaluate clinical characteristics, quality of life (QoL) and effectiveness in patients with menstrual cycle disorders (MCDs) including abnormal uterine bleeding, dysmenorrhea and mastodynia/mastalgia related to premenstrual syndrome taking the Vitex agnus-castus (VAC) products Cyclodynon® or Mastodynon® in a real-world setting.

Methods

A single-center retrospective longitudinal cohort study (3 ± 1 months), using data obtained from healthcare data archive and telephone interviews. The main study variables were changes in bleeding, menstrual pain, breast tenderness and patients’ QoL.

Results

Data from 1700 women with a mean age of 30.2 years (± 6.3) were analyzed. The most common MCDs were dysmenorrhea (43.8%) and mastodynia/mastalgia (21.1%). Three-month treatment with VAC extract substantially decreased the percentage of patients with irregular cycle (from 9.1% to 0.1%) and breast tenderness (from 39.9% to 0.8%). Improvement in bleeding intensity, frequency and menstrual pain was experienced by 83.4%, 79.2%, and 85.2% of the patients, respectively. When analyzed by disease category, these parameters improved in almost all dysmenorrhea patients, while they improved to a lesser extent in mastodynia/mastalgia patients. QoL improved in all aspects, but was reported by a higher proportion of dysmenorrhea patients compared to mastodynia/mastalgia patients. Treatment was overall well tolerated with a favorable safety profile.

Conclusion

These real-world data demonstrate the effectiveness of the VAC-containing products Cyclodynon® and Mastodynon® in the three-month treatment of MCDs, with a pronounced improvement in key disease symptoms and QoL. Intriguingly, while QoL was generally greatly improved, the response to VAC therapy varied depending on the type of underlying MCD.
Strong posterior contraction rates via Wasserstein dynamics
Authors: Dolera Emanuele , Favaro Stefano , Mainini Edoardo
Published: February 2024

In Bayesian statistics, posterior contraction rates (PCRs) quantify the speed at which the posterior distribution concentrates on arbitrarily small neighborhoods of a true model, in a suitable way, as the sample size goes to infinity. In this paper, we develop a new approach to PCRs, with respect to strong norm distances on parameter spaces of functions. Critical to our approach is the combination of a local Lipschitz-continuity for the posterior distribution with a dynamic formulation of the Wasserstein distance, which allows to set forth an interesting connection between PCRs and some classical problems arising in mathematical analysis, probability and statistics, e.g., Laplace methods for approximating integrals, Sanov’s large deviation principles in the Wasserstein distance, rates of convergence of mean Glivenko–Cantelli theorems, and estimates of weighted Poincaré–Wirtinger constants. We first present a theorem on PCRs for a model in the regular infinite-dimensional exponential family, which exploits sufficient statistics of the model, and then extend such a theorem to a general dominated model. These results rely on the development of novel techniques to evaluate Laplace integrals and weighted Poincaré–Wirtinger constants in infinite-dimension, which are of independent interest. The proposed approach is applied to the regular parametric model, the multinomial model, the finite-dimensional and the infinite-dimensional logistic-Gaussian model and the infinite-dimensional linear regression. In general, our approach leads to optimal PCRs in finite-dimensional models, whereas for infinite-dimensional models it is shown explicitly how the prior distribution affect PCRs.
Oral Candida carriage and resistance against common antifungal agents in hematopoietic stem cell transplantation recipients
Authors: Mauramo Matti , Tonoz Nurgül , Halter Jörg , Joseph Betsy , Waltimo Tuomas
Published: February 2024

Purpose

Allogeneic hematopoietic stem cell transplant (HSCT) recipients receiving long-term and high-dose immunosuppressive medications suffer commonly from oral candida infections. This prospective cohort study examined oral fungal carriage in HSCT recipients and screened the susceptibility against commonly used antifungal agents. An increasing oral occurrence of Candida spp. and the development of resistance against clinically administered fluconazole were hypothesized.

Methods

Two hundred HSCT recipients were included and followed up for 2 years post-HSCT. Oral microbiological specimens were analyzed with matrix-assisted laser desorption/ionization-time of flight mass spectrometry assays (MALDI-TOF). The colorimetric method was applied for the susceptibility testing by commercially available Sensititre YeastOne (SYO®, TREK Diagnostics Systems, Thermo-Fisher, UK).

Results

The prevalence of oral Candida spp. carriage increased statistically significantly after a year post-HSCT being 30, 26, 35, 44, and 47%, pre-HSCT, 3, 6, 12, and 24 months post-HSCT, respectively. Altogether, 169 clinical oral Candida strains were isolated. Fourteen Candida spp. were identified, and C. albicans was predominant in 74% of the isolates pre-HSCT with a descending prevalence down to 44% 2 years post-HSCT. An increasing relative proportion of non-albicans species post-HSCT was evident. No development of resistance of C. albicans against fluconazole was found. Instead, a shift from C. albicans towards non-albicans species, especially C. dubliensis, C. glabrata, and relatively seldom found C. krusei, was observed.

Conclusion

Oral Candida carriage increases after HSCT. Instead of the expected development of resistance of C. albicans against fluconazole, the relative proportion of non-albicans strains with innate resistance against azole-group antifungals increased.
Robust generation expansion planning in power grids under renewable energy penetration via honey badger algorithm
Authors: Abou El-Ela Adel A. , El-Sehiemy Ragab A. , Shaheen Abdullah M. , Shalaby Ayman S. , Mouwafi Mohamed T.
Published: February 2024

Robust reliability Generation Expansion Planning (GEP) turns out to be a crucial step for an efficient energy management system in a modern power grid, especially under renewable energy employment. The integration of all such components in a GEP model makes it a large-scale, nonlinear, and mixed-variable mathematical modeling problem. In this paper, the presence of wind energy uncertainty is analyzed. Both long and short-term uncertainties are incorporated into the proposed GEP model. The first step concerns the impact of long-term wind uncertainties through the annual variations of the capacity credit of two real sites in Egypt at Zafaranh and Shark El-ouinate. The second step deals with the short-term uncertainties of each wind site. The wind speed uncertainty of each wind site is modeled by probability distribution function. Then, wind power is estimated from the wind power curve for each wind site and Monte-Carlo Simulation is performed. Fast Gas Turbine and/or Pump Hydro Storage are incorporated to cope with short-term uncertainties. Sensitivity analysis is implemented for 3, 6, and 12 stages as short and long planning horizons to minimize the total costs with wind energy penetration and emission reduction over planning horizons. Also, a novel Honey Badger Algorithm (HBA) with model modifications such as Virtual Mapping Procedure, Penalty Factor Approach, and the Modified of Intelligent Initial Population Generation is utilized for solving the proposed GEP problem. The obtained results are compared with other algorithms to ensure the superior performance of the proposed HBA. According to the results of the applicable test systems, the proposed HBA performs better than the others, with percentage reductions over CSA, AO, BES, and PSO ranging up to 4.2, 2.72, 2.7, and 3.4%, respectively.
Multimodal meta-learning through meta-learned task representations
Authors: Vettoruzzo Anna , Bouguelia Mohamed-Rafik , Rögnvaldsson Thorsteinn
Published: February 2024

Few-shot meta-learning involves training a model on multiple tasks to enable it to efficiently adapt to new, previously unseen tasks with only a limited number of samples. However, current meta-learning methods assume that all tasks are closely related and belong to a common domain, whereas in practice, tasks can be highly diverse and originate from multiple domains, resulting in a multimodal task distribution. This poses a challenge for existing methods as they struggle to learn a shared representation that can be easily adapted to all tasks within the distribution. To address this challenge, we propose a meta-learning framework that can handle multimodal task distributions by conditioning the model on the current task, resulting in a faster adaptation. Our proposed method learns to encode each task and generate task embeddings that modulate the model’s activations. The resulting modulated model become specialized for the current task and leads to more effective adaptation. Our framework is designed to work in a realistic setting where the mode from which a task is sampled is unknown. Nonetheless, we also explore the possibility of incorporating auxiliary information, such as the task-mode-label, to further enhance the performance of our method if such information is available. We evaluate our proposed framework on various few-shot regression and image classification tasks, demonstrating its superiority over other state-of-the-art meta-learning methods. The results highlight the benefits of learning to embed task-specific information in the model to guide the adaptation when tasks are sampled from a multimodal distribution.
Biosensor for ATP detection via aptamer-modified PDA@POSS nanoparticles synthesized in a microfluidic reactor
Authors: Kibar Güneş , Şahinoğlu O. Berkay , Kılınçlı Betül , Erdem E. Yegan , Çetin Barbaros , Özalp V. Cengiz
Published: February 2024

This study introduces aptamer-functionalized polyhedral oligomeric silsesquioxane (POSS) nanoparticles for adenosine triphosphate (ATP) detection where the POSS nanoparticles were synthesized in a one-step, continuous flow microfluidic reactor utilizing thermal polymerization. A microemulsion containing POSS monomers was generated in the microfluidic reactor which was designed to prevent clogging by using a continuous oil flow around the emulsion during thermal polymerization. Surfaces of POSS nanoparticles were biomimetically modified by polydopamine. The aptamer sequence for ATP was successfully attached to POSS nanoparticles. The aptamer-modified POSS nanoparticles were tested for affinity-based biosensor applications using ATP as a model molecule. The nanoparticles were able to capture ATP molecules successfully with an affinity constant of 46.5 $$\upmu $$
μ
M. Based on this result, it was shown, for the first time, that microfluidic synthesis of POSS nanoparticles can be utilized in designing aptamer-functionalized nanosystems for biosensor applications. The integration of POSS in biosensing technologies not only exemplifies the versatility and efficacy of these nanoparticles but also marks a significant contribution to the field of biorecognition and sample preparation.