bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serum IgG levels in children 6 months after SARS-CoV-2 infection and comparison with adults
Authors: Bloise Silvia , Marcellino Alessia , Testa Alessia , Dilillo Anna , Mallardo Saverio , Isoldi Sara , Martucci Vanessa , Sanseviero Maria Teresa , Del Giudice Emanuela , Iorfida Donatella , Ventriglia Flavia , Lubrano Riccardo 
Published: May 2021

AbstractSince the outbreak of SARS-CoV-2 among the population has occurred quite recently, there is a lack of evidence on the long-term duration of antibody response, especially in children. It is therefore crucial to clarify this aspect, considering its implications in the development of successful surveillance strategies, therapies, and vaccinations. The aim of this study was to assess the antibody response in a children group after SARS-CoV-2 infection, and to compare it with that of their parents affected by SARS-CoV-2 infection. We enrolled 12 children and their parents, both groups being affected by COVID-19 in April 2020. In the children’s group, we collected real-time RT-PCR cycle threshold (Ct) values and gene characterization of first nasal-throat swab at the time of diagnosis (T0); 30 days after the diagnosis (T30), we performed blood tests to detect anti-SARS-CoV-2 IgM and IgG. Finally, 180 days after the diagnosis (T180), we measured anti-SARS-CoV-2 IgG in both children and parents. In children, antibody levels declined significantly at 180 days (T180) after first measurement (T30). There were no significant differences in IgG level related to age, sex, and clinical manifestations. We found a significant correlation between IgG titers at T30 and Ct value of gene N. Children showed a lower level of antibodies against SARS-CoV-2 at T180 compared to their parents.Conclusion: Antibody responses in children waned 180 days after SARS-CoV-2 infection, and at the same time, their parents showed a different antibody response to the virus. These results highlight that serological tests should be used with caution in surveillance strategies among the general population.

What is known:• Currently is not known how long antibody response will be maintained or if it protects from reinfection.• Recent reports in adults suggest that antibodies to SARS-CoV-2 declined several months after infection, but data are missing in pediatric age.

What is new:• We showed that antibody responses to SARS-CoV-2 wane several months after infection also in children with quantitative differences in antibody levels between children and adults.• In this context, serological tests should be used with caution in surveillance strategies.
Burnout amongst neurosurgical trainees in the UK and Ireland
Authors: Salloum Nadia Liber , Copley Phillip Correia , Mancuso-Marcello Marco , Emelifeonwu John , Kaliaperumal Chandrasekaran 
Published: May 2021

Abstract
Introduction
Burnout is becoming an increasingly recognised phenomenon within the medical profession. This study aims to investigate the presence of burnout amongst neurosurgical trainees in the UK and Ireland as well as investigating potential exacerbating and protective factors.

Method
An online survey was sent to all neurosurgical trainees in the UK and Ireland via the British Neurosurgical Trainees’ Association (BNTA) mailing list. Responding participants anonymously completed the Copenhagen Burnout Inventory (CBI) and answered questions about known risk factors for burnout including workplace environment, workplace bullying, time spent on leisure activities and sleep and reported likelihood of leaving neurosurgery. We also collated data on responders’ demographics. We compared CBI scores for participants with and without risk factors to determine correlation with CBI.

Results
There were 75 respondents (response rate 42%) from a range of ages and all training grades, 72% of whom were male. The median CBI score was 38.85 (IQR 17.76). Participants showed a higher degree of personal and workplace burnout (median CBIs of 47.02, IQR 25.00; and 49.14, IQR 19.64, respectively) compared with patient-related burnout (median CBI 18.67, IQR 25.00). Participants with the following self-reported risk factors were significantly more likely to have higher CBIs: workplace bullying (p = 0.01), getting on less well with colleagues (p < 0.05), working longer hours (p < 0.05) and insufficient sleep, exercise and leisure time (all p < 0.01). Those with higher CBI scores were more likely to consider leaving neurosurgical training (p = 0.01).

Conclusion
We identified a high burnout incidence in a cohort representative of UK neurosurgical trainees, although our results may have been skewed somewhat by selection bias. We determined potential risk factors for burnout related to specific workplace stressors and time for non-work activities. In the future, changes to training curricula should address these issues, aiming to improve training, enhance patient care and reduce attrition rates.
Electronic structure and reactivity of tirapazamine as a radiosensitizer
Authors: Romero José , Maihom Thana , Limão-Vieira Paulo , Probst Michael 
Published: May 2021

AbstractTirapazamine (TP) has been shown to enhance the cytotoxic effects of ionizing radiation in hypoxic cells, thus making it a candidate for a radiosensitizer. This selective behavior is often directly linked to the abundance of O2. In this paper, we study the electronic properties of TP in vacuum, micro-hydrated from one up to three molecules of water and embedded in a continuum of water. We discuss electron affinities, charge distribution, and bond dissociation energies of TP, and find that these properties do not change significantly upon hydration. In agreement with its large electron affinity, and bond breaking triggered by electron attachment requires energies higher than 2.5 eV, ruling out the direct formation of bioactive TP radicals. Our results suggest, therefore, that the selective behavior of TP cannot be explained by a one-electron reduction from a neighboring O2 molecule. Alternatively, we propose that TP’s hypoxic selectivity could be a consequence of O2 scavenging hydrogen radicals.
Discrete element modelling of rockfill railway embankments
Authors: de Frias Lopez Ricardo , Larsson Stefan , Silfwerbrand Johan 
Published: May 2021

AbstractThere is a need of reducing the uncertainty in traffic loading-induced settlements within railway embankments. A previously developed model for unbound stone-based materials has been implemented for modelling rockfill embankments. Particles were represented by simple breakable tetrahedral clumps of spheres with four asperities each. Both corner breakage and particle splitting were allowed. Embankments with heights between 2 and 10 m were generated by successive dumping and compaction of layers of clumps on top of each other, mimicking the construction of real embankments. Cyclic loading of the embankments representing railway traffic, for both breakable and unbreakable assemblies, was carried out. Results show that the mechanical response is marked by a substantial degree of uncertainty exacerbated by particle degradation, especially for intermediate to high embankments. An analysis of particle rotation showed that particle rearrangement mostly accumulates in the top layers, resulting in a lack of influence of embankment height on settlements. Breakage, even being of (very) limited magnitude, had a statistically significant effect. Good agreement with common geostatic theories predicting horizontal pressures was also observed. Regarding resilient response, linear stiffening with embankment height is observed with a minor influence of breakage. All in all, it is shown that the specific scale, boundary and stress conditions of embankments results in a behaviour deviating from that observed under triaxial conditions. Therefore, the key contribution is showing that it is possible to realistically model high rockfill embankments under a large number of loading cycles and furthermore including degradation, something not attempted to date.
Graphic abstract
Clinical evaluation of rapid point-of-care antigen tests for diagnosis of SARS-CoV-2 infection
Authors: Koeleman Johannes G. M. , Brand Henk , de Man Stijn J. , Ong David S. Y. 
Published: May 2021

AbstractThe RT-qPCR in respiratory specimens is the gold standard for diagnosing acute COVID-19 infections. However, this test takes considerable time before test results become available, thereby delaying patients from being diagnosed, treated, and isolated immediately. Rapid antigen tests could overcome this problem. In the first study, clinical performances of five rapid antigen tests were compared to RT-qPCR in upper respiratory specimens from 40 patients with positive and 40 with negative RTq-PCR results. In the second study, the rapid antigen test with one of the best test characteristics (Romed) was evaluated in a large prospective collection of upper respiratory specimens from 900 different COVID-19-suspected patients (300 emergency room patients, 300 nursing home patients, and 300 health care workers). Test specificities ranged from 87.5 to 100.0%, and test sensitivities from 55.0 to 80.0%. The clinical specificity of the Romed test was 99.8% (95% CI 98.9–100). Overall clinical sensitivity in the study population was 73.3% (95% CI 67.9–78.2), whereas sensitivity in the different patient groups varied from 65.3 to 86.7%. Sensitivity was 83.0 to 86.7% in patients with short duration of symptoms. In a population with a COVID-19 prevalence of 1%, the negative predictive value in all patients was 99.7%. There is a large variability in diagnostic performance between rapid antigen tests. The Romed rapid antigen test showed a good clinical performance in patients with high viral loads (RT-qPCR cycle threshold ≤30), which makes this antigen test suitable for rapid identification of COVID-19-infected health care workers and patients.
Usability evaluation of a virtual reality smartphone app for a living museum
Authors: Othman Mohd Kamal , Nogoibaeva Altynai , Leong Lai San , Barawi Mohamad Hardyman 
Published: May 2021

AbstractThis paper elaborates the empirical evidence of a usability evaluation of a VR and non-VR virtual tour application for a living museum. The System Usability Scale (SUS) was used in between participants experiments (Group 1: non-VR version and Group 2: VR version) with 40 participants. The results show that the mean scores of all components for the VR version are higher compared to the non-VR version, overall SUS score (72.10 vs 68.10), usability score (75.50 vs 71.70), and learnability (58.40 vs 57.00). Further analysis using a two-tailed independent t test showed no difference between the non-VR and VR versions. Additionally, no significant difference was observed between the groups in the context of gender, nationality, and prior experience (other VR tour applications) for overall SUS score, usability score, and learnability score. Α two-tailed independent t test indicated no significant difference in the usability score between participants with VR experience and no VR experience. However, a significant difference was found between participants with VR experience and no VR experience for both SUS score (t(38) = 2.17, p = 0.037) and learnability score (t(38) = 2.40, p = 0.021). The independent t test results indicated a significant difference between participant with and without previous visits to SCV for the usability score (t(38) = −2.31, p = 0.027), while there was no significant differences observed in other components. It can be concluded that both versions passed based on the SUS score. However, the sub-scale usability and learnability scores indicated some usability issue.
Design and dynamic analysis of integrated architecture for vibration energy harvesting including piezoelectric frame and mechanical amplifier
Authors: Duan Xiangjian , Cao Dongxing , Li Xiaoguang , Shen Yongjun 
Published: May 2021

AbstractVibration energy harvesters (VEHs) can transform ambient vibration energy to electricity and have been widely investigated as promising self-powered devices for wireless sensor networks, wearable sensors, and applications of a micro-electro-mechanical system (MEMS). However, the ambient vibration is always too weak to hinder the high energy conversion efficiency. In this paper, the integrated frame composed of piezoelectric beams and mechanical amplifiers is proposed to improve the energy conversion efficiency of a VEH. First, the initial structures of a piezoelectric frame (PF) and an amplification frame (AF) are designed. The dynamic model is then established to analyze the influence of key structural parameters on the mechanical amplification factor. Finite element simulation is conducted to study the energy harvesting performance, where the stiffness characteristics and power output in the cases of series and parallel load resistance are discussed in detail. Furthermore, piezoelectric beams with variable cross-sections are introduced to optimize and improve the energy harvesting efficiency. Advantages of the PF with the AF are illustrated by comparison with conventional piezoelectric cantilever beams. The results show that the proposed integrated VEH has a good mechanical amplification capability and is more suitable for low-frequency vibration conditions.
Heart Rate Variability Reactivity to Food Image Stimuli is Associated with Body Mass Index
Authors: Chang Jung-Chi , Huang Wei-Lieh , Liu Chao-Yu , Tseng Meg Mei-Chih , Yang Cheryl C. H. , Kuo Terry B. J. 
Published: May 2021

AbstractAppetitive control is driven by the hedonic response to food and affected by several factors. Heart rate variability (HRV) signals have been used to index autonomic activity and arousal levels towards visual stimuli. The current research aimed to examine the influence of body mass index (BMI), disordered eating behaviors, and sex on the HRV reactivity to food in a nonclinical sample. Thirty-eight healthy male and sixty-one healthy female participants completed questionnaires assessing disordered eating symptoms. HRV was recorded when the participants received visual stimuli of high-calorie food, neutral and negative emotional signals. Generalized estimating equation models were used to investigate the associations between HRV, BMI, disordered eating behaviors, and sex across the three stimulus types. Male participants demonstrated a higher ratio of low-frequency power to high-frequency power (LF/HF) than females across all the stimulus types. An increase in LF/HF reactivity to food signals was observed in all the study subjects. The moderation effect of BMI on LF/HF in response to food signals was also observed. Our study suggests that body weight may play a role in the interaction between sympathetic activity and food stimuli; however, how the interaction between sympathetic activity and food stimuli contributes to diet control warrants further investigation.
Stimulation of de novo glutathione synthesis by nitrofurantoin for enhanced resilience of hepatocytes
Authors: Wijaya Lukas S. , Rau Carina , Braun Theresa S. , Marangoz Serif , Spegg Vincent , Vlasveld Matthijs , Albrecht Wiebke , Brecklinghaus Tim , Kamp Hennicke , Beltman Joost B. , Hengstler Jan G. , van de Water Bob , Leist Marcel , Schildknecht Stefan 
Published: May 2021

AbstractToxicity is not only a function of damage mechanisms, but is also determined by cellular resilience factors. Glutathione has been reported as essential element to counteract negative influences. The present work hence pursued the question how intracellular glutathione can be elevated transiently to render cells more resistant toward harmful conditions. The antibiotic nitrofurantoin (NFT) was identified to stimulate de novo synthesis of glutathione in the human hepatoma cell line, HepG2, and in primary human hepatocytes. In intact cells, activation of NFT yielded a radical anion, which subsequently initiated nuclear-factor-erythroid 2-related-factor-2 (Nrf2)-dependent induction of glutamate cysteine ligase (GCL). Application of siRNA-based intervention approaches confirmed the involvement of the Nrf2-GCL axis in the observed elevation of intracellular glutathione levels. Quantitative activation of Nrf2 by NFT, and the subsequent rise in glutathione, were similar as observed with the potent experimental Nrf2 activator diethyl maleate. The elevation of glutathione levels, observed even 48 h after withdrawal of NFT, rendered cells resistant to different stressors such as the mitochondrial inhibitor rotenone, the redox cycler paraquat, the proteasome inhibitors MG-132 or bortezomib, or high concentrations of NFT. Repurpose of the antibiotic NFT as activator of Nrf2 could thus be a promising strategy for a transient and targeted activation of the endogenous antioxidant machinery.
Influence of biological origin on the tensile properties of cellulose nanopapers
Authors: Kontturi Katri S. , Lee Koon-Yang , Jones Mitchell P. , Sampson William W. , Bismarck Alexander , Kontturi Eero 
Published: May 2021

Abstract
Cellulose nanopapers provide diverse, strong and lightweight templates prepared entirely from sustainable raw materials, cellulose nanofibers (CNFs). Yet the strength of CNFs has not been fully capitalized in the resulting nanopapers and the relative influence of CNF strength, their bonding, and biological origin to nanopaper strength are unknown. Here, we show that basic principles from paper physics can be applied to CNF nanopapers to illuminate those relationships. Importantly, it appeared that ~ 200 MPa was the theoretical maximum for nanopapers with random fibril orientation. Furthermore, we demonstrate the contrast in tensile strength for nanopapers prepared from bacterial cellulose (BC) and wood-based nanofibrillated cellulose (NFC). Endemic amorphous polysaccharides (hemicelluloses) in NFC act as matrix in NFC nanopapers, strengthening the bonding between CNFs just like it improves the bonding between CNFs in the primary cell wall of plants. The conclusions apply to all composites containing non-woven fiber mats as reinforcement.

Graphic abstract
Computing mixed strategies equilibria in presence of switching costs by the solution of nonconvex QP problems
Authors: Liuzzi G. , Locatelli M. , Piccialli V. , Rass S. 
Published: May 2021

AbstractIn this paper we address game theory problems arising in the context of network security. In traditional game theory problems, given a defender and an attacker, one searches for mixed strategies which minimize a linear payoff functional. In the problems addressed in this paper an additional quadratic term is added to the minimization problem. Such term represents switching costs, i.e., the costs for the defender of switching from a given strategy to another one at successive rounds of a Nash game. The resulting problems are nonconvex QP ones with linear constraints and turn out to be very challenging. We will show that the most recent approaches for the minimization of nonconvex QP functions over polytopes, including commercial solvers such as and , are unable to solve to optimality even test instances with $$n=50$$

n
=
50

variables. For this reason, we propose to extend with them the current benchmark set of test instances for QP problems. We also present a spatial branch-and-bound approach for the solution of these problems, where a predominant role is played by an optimality-based domain reduction, with multiple solutions of LP problems at each node of the branch-and-bound tree. Of course, domain reductions are standard tools in spatial branch-and-bound approaches. However, our contribution lies in the observation that, from the computational point of view, a rather aggressive application of these tools appears to be the best way to tackle the proposed instances. Indeed, according to our experiments, while they make the computational cost per node high, this is largely compensated by the rather slow growth of the number of nodes in the branch-and-bound tree, so that the proposed approach strongly outperforms the existing solvers for QP problems.
Female reproductive organs of Brassica napus are more sensitive than male to transient heat stress
Authors: Chen Sheng , Saradadevi Renu , Vidotti Miriam S. , Fritsche-Neto Roberto , Crossa Jose , Siddique Kadambot H. M. , Cowling Wallace A. 
Published: May 2021

AbstractOilseed rape (Brassica napus L.) is sensitive to heat stress during the reproductive stage, but it is not clear whether the male and female reproductive organs differ in their sensitivity to heat stress. In this study, full diallel crossing experiments were conducted among four genotypes of B. napus under control, moderate and high heat stress conditions for five days immediately before and two days after crossing. General combining ability (GCA), specific combining ability (SCA) and reciprocal effects were analyzed to evaluate the genetic basis of heat stress tolerance in male and female reproductive organs. High female temperature (Tf) and high male temperature (Tm) reduced the number of fertile pods and seeds set per floret, and the significant Tf × Tm interaction indicated that female reproductive organs were more sensitive to heat stress than male reproductive organs. There were no overall GCA, SCA or reciprocal effects across all combinations of Tf and Tm. However, a significant reciprocal × Tf effect was found, suggesting that genotypes differed in their ability to set fertile pods and seeds as Tf increased. The relative heat tolerance of G1 as a female increased as Tf increased, and the relative heat tolerance of G2 as a male decreased as Tf increased. In summary, reciprocal diallel crossing has demonstrated that female reproductive organs of B. napus are more sensitive than male to transient heat stress at the early flowering stage, and genotypes differ in relative heat tolerance in the male and female reproductive organs as Tf increases.
Physiological and environmental control of seed germination timing in Mediterranean mountain populations of Gundelia tournefortii
Authors: Mattana Efisio , Gómez-Barreiro Pablo , Hani Nizar Youssef , Abulaila Khaled , Ulian Tiziana 
Published: May 2021

AbstractFruit and seed morphology interact with embryo physiology and environmental conditions to control seed germination timing. This interaction plays a pivotal role in ecosystems with narrow windows for seedling establishment, such as the Mediterranean mountains. In this study, we investigated the germination responses of the secondary capitula (disseminules) ofGundelia tournefortiifrom East Mediterranean mountain populations. When incubated at 15 °C, intact capitula did not reach 20% of final germination, with or without the addition in the germination substrate of GA3(250 mg L−1), while extracted fruits reached 50% of germination, which increased to ca. 70% when treated with GA3. Cold stratification enhanced final germination of the capitula at 15 °C to ca. 65%, although almost half of the initially sown capitula germinated during the second month of stratification at 5 °C. During the stratification at 5 °C, peak puncture force needed to pierce the basal part of the capitula decreased linearly and capitula started germinating after one month, which corresponded to a peak puncture force of 0.41–0.35 N. These findings highlight the presence of mechanical and hormonal components of physiological seed dormancy. The morphology of the disseminules controls seed germination timing, by interacting with cold winter temperatures and starting seed germination only in early winter. These findings not only provide new insights on the reproduction from seeds of this plant, but by highlighting high germination of cold-stratified intact capitula, can also support plant propagation programmes for this key wild edible species, very important for food security and the livelihoods of local communities in the East Mediterranean region.