bluuebunny/crossref_metadata_2025 huggingface dataset:
Type II supernovae from the Carnegie Supernova Project-I
Authors: Martinez L. , Bersten M. C. , Anderson J. P. , Hamuy M. , González-Gaitán S. , Förster F. , Orellana M. , Stritzinger M. , Phillips M. M. , Gutiérrez C. P. , Burns C. , Contreras C. , de Jaeger T. , Ertini K. , Folatelli G. , Galbany L. , Hoeflich P. , Hsiao E. Y. , Morrell N. , Pessi P. J. , Suntzeff N. B.
Published: December 2021

Linking supernovae to their progenitors is a powerful method for furthering our understanding of the physical origin of their observed differences while at the same time testing stellar evolution theory. In this second study of a series of three papers where we characterise type II supernovae (SNe II) to understand their diversity, we derive progenitor properties (initial and ejecta masses and radius), explosion energy, and56Ni mass and its degree of mixing within the ejecta for a large sample of SNe II. This dataset was obtained by the Carnegie Supernova Project-I and is characterised by a high cadence of SNe II optical and near-infrared light curves and optical spectra that were homogeneously observed and processed. A large grid of hydrodynamical models and a fitting procedure based on Markov chain Monte Carlo methods were used to fit the bolometric light curve and the evolution of the photospheric velocity of 53 SNe II. We infer ejecta masses of between 7.9 and 14.8M⊙, explosion energies between 0.15 and 1.40 foe, and56Ni masses between 0.006 and 0.069M⊙. We define a subset of 24 SNe (the ‘gold sample’) with well-sampled bolometric light curves and expansion velocities for which we consider the results more robust. Most SNe II in the gold sample (∼88%) are found with ejecta masses in the range of ∼8−10M⊙, coming from low zero-age main-sequence masses (9−12M⊙). The modelling of the initial-mass distribution of the gold sample gives an upper mass limit of 21.3$ ^{+3.8}_{-0.4} $M⊙and a much steeper distribution than that for a Salpeter massive-star initial mass function (IMF). This IMF incompatibility is due to the large number of low-mass progenitors found – when assuming standard stellar evolution. This may imply that high-mass progenitors lose more mass during their lives than predicted. However, a deeper analysis of all stellar evolution assumptions is required to test this hypothesis.
Constrained stochastic LQ control on infinite time horizon with regime switching
Authors: Hu Ying , Shi Xiaomin , Xu Zuo Quan
Published: December 2021

This paper is concerned with a stochastic linear-quadratic (LQ) optimal control problem on infinite time horizon, with regime switching, random coefficients, and cone control constraint. To tackle the problem, two new extended stochastic Riccati equations (ESREs) on infinite time horizon are introduced. The existence of the nonnegative solutions, in both standard and singular cases, is proved through a sequence of ESREs on finite time horizon. Based on this result and some approximation techniques, we obtain the optimal state feedback control and optimal value for the stochastic LQ problem explicitly. Finally, we apply these results to solve a lifetime portfolio selection problem of tracking a given wealth level with regime switching and portfolio constraint.
Wellenreiten – 12 Monate COVID-19 im Maximalversorger
Authors: Fistera David , Pabst Dirk , Falk Maximilian , Anastasiou Olympia E. , Goer Stefan , Dolff Sebastian , Konik Margarethe , Herbstreit Frank , Taube Christian , Kill Clemens , Risse Joachim
Published: December 2021

Einleitung Mit weit mehr als 1400 stationär behandelten COVID-19-Patienten ist die Universitätsmedizin Essen der größte COVID-19-Versorger der Region Rhein-Ruhr. Wir präsentieren die Daten unserer Patienten aus den ersten 12 Monaten der Pandemie und die hieraus entstandenen praktischen Konzepte.

Methode Retrospektive Analyse aller 1396 stationären COVID-19-Patienten, die zwischen dem 1. März 2020 und 28. Februar 2021 versorgt wurden, im Hinblick auf Komorbiditäten, Überleben und Komplikationen im Verlauf. Es erfolgte ein Gruppenvergleich zwischen Patienten auf Normalstation und Überwachungs-/ Intensivstation.

Ergebnisse Bei einer Gesamtmortalität von 19,8 % (277/1396) starben 10,6 % (93/877) der Patienten auf Normalstation und 35,5 % (184/519) der Patienten auf Intensiv- und Überwachungsstationen im klinischen Verlauf. Hierbei waren ein Alter über 60 Jahre, Adipositas, maschinelle Beatmung, NO-Therapie, ECMO-Therapie sowie akutes Nierenversagen und Apoplex im Therapieverlauf unabhängige Prädiktoren für Mortalität.

Fazit Die Mortalität unseres Kollektivs auf Normal- bzw. Intensivstationen liegt im Rahmen international publizierter Daten. Sowohl die hohe Rate von Komplikationen bei schwerem Verlauf als auch die große Bedeutung einfacher Komorbiditäten kann eindrücklich gezeigt werden. Das mittlere Alter der Patienten ist mit 60 Jahren auf Normalstation und 63 Jahren auf Intensivstationen überraschend niedrig. Maximaler Patienten- und Personalschutz, eine rasche und effektive Teststrategie im Rahmen der primären Triage, standardisierte Abläufe von der Notaufnahme bis zur Intensivstation sowie eine dynamische tagesaktuelle Anpassung der Ressourcen können eine hohe Versorgungsqualität, auch während der Pandemie, sichern.
Antimicrobial Formulation of Chrysopogon zizanioides Essential Oil in an Emulsified Lotion for Acne
Authors: Kurrimboccus Fadilah , Orchard Ané , Danckwerts Michael Paul , van Vuuren Sandy
Published: December 2021

Acne is a skin condition arising from excess sebum production and microbial overgrowth within the pilosebaceous unit. Several commercial essential oils have shown promising activity against acne-related pathogens. Due to their volatility and thermal instability, the formulation of essential oils into commercial products remains a pharmaceutical challenge. Thus, this study aimed to develop a viable anti-acne topical treatment as an oil-in-water emulsified lotion to overcome these challenges. Chrysopogon zizanioides (vetiver) displayed noteworthy antimicrobial activity with a mean minimum inhibitory concentration of 0.14 mg/mL against Cutibacterium acnes, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. Emulsified lotions containing C. zizanioides were developed through the hydrophilic-lipophilic balance approach. At tested hydrophilic-lipophilic balance values of 8, 9, and 10, C. zizanioides emulsified
lotions displayed maximum stability at hydrophilic-lipophilic balance 9 with a minimum change in mean droplet size and polydispersity index of 20.61 and 33.33%, respectively, over 84 days. The C. zizanioides emulsified lotion at optimum hydrophilic-lipophilic balance 9 completely inhibited the growth of C. acnes and killed S. aureus, S. epidermidis, and S. pyogenes within 24 h. Additionally, the lotion retained antimicrobial activity against these test micro-organisms over the 84-day stability test period. Thus, the C. zizanioides emulsified lotion demonstrated physical stability and antimicrobial efficiency, making it an ideal natural product anti-acne treatment.
Impact of the COVID 19 Pandemic on Radiological Imaging in Germany
Authors: Schmidbauer Martina , Grenacher Lars , Juchems Markus S. , Memmel Erik , Lauenstein Thomas , Schreyer Andreas G. , Verloh Niklas , Becker Claus , Vogl Thomas J. , Wessling Johannes , Wacker Frank K. , Ringe Kristina Imeen
Published: December 2021

Purpose To analyze the impact of the COVID-19 pandemic in 2020 on the radiological imaging volume in Germany.

Materials und Methods In this retrospective multicenter study, we analyzed CT and MRI examinations of 7 radiology institutes across Germany from January to December 2020. The imaging volume was compared to 2019 (Wilcoxon-Mann-Whitney test). Modality, patient service locations, and examined body parts were assessed in consideration of time periods of the pandemic. In addition, correlation with the incidence of SARS-CoV-2 cases and associated death was performed (Spearman-test).

Results In total, in 2020, imaging volume declined by 4 % (n = 8314) compared with 2019 (p < 0.05). The hard lockdown during the first pandemic wave (calendar week 12–16, March 22 – April 19) revealed the highest decrease with 29 % (n = 894, p < 0.01), with the greatest decrease in CT (36 % vs. MRI 26 %), outpatients (38 %, p < 0.01), and imaging of the spine and extremities (51–72 %, < 0.05 – p < 0.01). Examinations referred from the emergency department (–13 %, p < 0.05) and CT of the chest (–16 %, p < 0.05) were least affected. With the end of the first wave, gradual normalization of the imaging volume was observed and persisted until the end of the observation period. A reduction of imaging volume negatively correlated with the incidence of SARS-CoV-2-positive cases and associated deaths (r = 0.28 and 0.49, p < 0.05 and p < 0.001).

Conclusion The COVID-19 pandemic was associated with a significant temporary decline in imaging volume. After the first lockdown period, a quick recovery was observed with radiologic imaging examinations steadily approaching prior-year figures.

Key points: 

Citation Format
Cytochalasan Alkaloids as TRAIL Sensitizers from an Endophytic Fungus
Chaetomium sp.
Authors: Gao Ying , Mao Ruihua , Liu Ye , Zhou Ming , Ruan Hanli
Published: December 2021

Two new cytochalasans with a rare 6/6/5/5/7 pentacyclic ring system, named
chaetoconvosins C−D (1−2), together with two known congeners
(3−4), were isolated from the fermentation of an endophytic
fungus, Chaetomium sp. SG-01, harbored in the fibrous roots of
Schisandra glaucescens Diels. Their structures including the absolute
configuration were elucidated by extensive spectroscopic (HRESIMS, NMR, and ECD)
and X-ray crystallographic analyses. The TRAIL-resistance-overcoming activity of
1–4 in a TRAIL-resistant HT29 colorectal cancer cell line was
evaluated, which revealed that co-treatment of 1–4 at 50 µM
with TRAIL (150 ng/mL) reduced the HT29 cell viability by 19.0%, 24.1%, 17.9%,
and 15.5%, respectively, compared to treatment with 1–4 alone.
Tinnitus Activities Treatment with Total and Partial Masking
Authors: Tyler Richard S. , Stocking Christina , Ji Haihong , Witt Shelley , Mancini Patricia C.
Published: December 2021

Abstract Background There are many counseling and sound therapy approaches to treat tinnitus. Counseling approaches range from providing information using directive or collaborative approaches. Sound therapies include strategies that use background sounds to
totally or partially mask tinnitus to reduce the prominence of or decrease the loudness or annoyance of the tinnitus. Purpose We evaluated the effectiveness of tinnitus activities treatment (TAT) in two groups, those without hearing aids (HA) and those who were provided with
HA. In both groups, comparisons were made among those receiving (1) counseling only, (2) counseling and partial masking, and (3) counseling and total masking. Research Design Participants were provided with HA or not, based on their choice, and then randomly assigned to one
of the three groups. The Tinnitus Handicap Questionnaire (THQ) was used as the primary measure. Results For those without HA, significant benefits were obtained for 8 out of 22 participants in the counseling group, 8 of 13 in the total masking group, and 8 of 24 in the partial
mask group. The average decrease in the THQ was 15% for the counseling group, 25% for the total mask, and 14% for the partial masking group. For those with HA; significant benefits were obtained for 5 of 16 in the counseling group, 3 of 14 in the total mask group, and 6 of 13 in the partial
mask group. The average decrease in the THQ score was 12% for counseling, 13% for total masking, and 16% for partial masking. No significant differences among groups were observed. Conclusion Individual differences were large. Many benefited from their treatment, but some did
not. We believe this was likely influenced by their expectations.
Effects of the Configuration of Hearing Loss on Consonant Perception between Simulated Bimodal and Electric Acoustic Stimulation Hearing
Authors: Yoon Yang-Soo , Whitaker George , Lee Yune S.
Published: December 2021

Abstract Background Cochlear implant technology allows for acoustic and electric stimulations to be combined across ears (bimodal) and within the same ear (electric acoustic stimulation [EAS]). Mechanisms used to integrate speech acoustics may be different between
the bimodal and EAS hearing, and the configurations of hearing loss might be an important factor for the integration. Thus, differentiating the effects of different configurations of hearing loss on bimodal or EAS benefit in speech perception (differences in performance with combined acoustic
and electric stimulations from a better stimulation alone) is important. Purpose Using acoustic simulation, we determined how consonant recognition was affected by different configurations of hearing loss in bimodal and EAS hearing. Research Design A mixed design
was used with one between-subject variable (simulated bimodal group vs. simulated EAS group) and one within-subject variable (acoustic stimulation alone, electric stimulation alone, and combined acoustic and electric stimulations). Study Sample Twenty adult subjects (10 for
each group) with normal hearing were recruited. Data Collection and Analysis Consonant perception was unilaterally or bilaterally measured in quiet. For the acoustic stimulation, four different simulations of hearing loss were created by band-pass filtering consonants with
a fixed lower cutoff frequency of 100 Hz and each of the four upper cutoff frequencies of 250, 500, 750, and 1,000 Hz. For the electric stimulation, an eight-channel noise vocoder was used to generate a typical spectral mismatch by using fixed input (200‐7,000 Hz)
and output (1,000‐7,000 Hz) frequency ranges. The effects of simulated hearing loss on consonant recognition were compared between the two groups. Results Significant bimodal and EAS benefits occurred regardless of the configurations of hearing loss and hearing
technology (bimodal vs. EAS). Place information was better transmitted in EAS hearing than in bimodal hearing. Conclusion These results suggest that configurations of hearing loss are not a significant factor for integrating consonant information between acoustic and electric
stimulations. The results also suggest that mechanisms used to integrate consonant information may be similar between bimodal and EAS hearing.
Pediatric Arabic Closed-Set Word-Recognition Test: Development and Evaluation of Psychometric Characteristics
Authors: Garadat Soha N. , Alkharabsheh Ana'am , Almasri Nihad A. , Hagr Abdulrahman
Published: December 2021

Abstract Background Speech audiometry materials are widely available in many different languages. However, there are no known standardized materials for the assessment of speech recognition in Arabic-speaking children. Purpose The aim of the study
was to develop and validate phonetically balanced and psychometrically equivalent monosyllabic word recognition lists for children through a picture identification task. Research Design A prospective repeated-measure design was used. Monosyllabic words were chosen from children's
storybooks and were evaluated for familiarity. The selected words were then divided into four phonetically balanced word lists. The final lists were evaluated for homogeneity and equivalency. Study Sample Ten adults and 32 children with normal hearing sensitivity were recruited.
Data Collection and Analyses Lists were presented to adult subjects in 5 dB increment from 0 to 60 dB hearing level. Individual data were then fitted using a sigmoid function from which the 50% threshold, slopes at the 50% points, and slopes at the 20 to 80% points
were derived to determine list psychometric properties. Lists were next presented to children in two separate sessions to assess their equivalency, validity, and reliability. Data were subjected to a mixed design analysis of variance. Results No statistically significant difference
was found among the word lists. Conclusion This study provided an evidence that the monosyllabic word lists had comparable psychometric characteristics and reliability. This supports that the constructed speech corpus is a valid tool that can be used in assessing speech recognition
in Arabic-speaking children.
Consumer Ratings of the Most Desirable Hearing Aid Attributes
Authors: Manchaiah Vinaya , Picou Erin M. , Bailey Abram , Rodrigo Hansapani
Published: December 2021

Abstract Background Modern hearing aids have various features and functionalities, such as digital wireless streaming, bilateral connectivity, rechargeability, and specialized programs, which allow for a multitude of hearing aid attributes (e.g., comfort, reliability,
and clarity). Consumers likely vary greatly in their preferences for these hearing aid attributes. Their preferences might be related to various demographic and hearing loss characteristics. Purpose The purposes of this study were to describe which hearing aid attributes consumers
find desirable when choosing their hearing aids and to explore factors that might predict preferences. Research Design Cross-sectional. Study Sample 14,993. Intervention Not applicable. Data Collection and Analysis In this retrospective
study, hearing aid attribute preferences were evaluated from consumers who answered questions in the Help Me Choose tool on the HearingTracker.com Web site. Chi-squared tests and correlation analyses were used to identify potential relationships between attribute preference and respondent
characteristics. Cluster analysis with Partitioning Around Medoids (PAM) was used to identify patterns of attribute preferences. Results Of the 21 hearing aid attributes queried, the four most favorably rated were improved ability to hear friends and family in quiet and in
noisy settings, physical comfort, and reliability, with 75 to 88% of respondents rating these attributes as very or extremely important. Type of hearing loss, technology level preference, and mobile phone brand were significantly associated with preferences for all 21 hearing aid attributes.
PAM cluster analysis unveiled two unique user groups based on their preference to hearing aid attributes. One-third of the respondents preferred high-end technology and favored all types of advanced attributes. The other two-thirds of users predominantly preferred either advanced or best match
and were more selective about which attributes were most important to them. Conclusion Patterns in preferences to hearing aid attributes help identify unique subgroups of consumers. Patient preferences for specific hearing aid attributes, in addition to audiologic characteristics,
could help audiologists in recommending hearing aids for their patients.
Computed Tomography–Guided Microcoil Localization of Pulmonary Nodules: Effects of Multiple Punctures
Authors: Tian Ye , An Jianli , Zou Zibo , Dong Yanchao , Wu Jingpeng , Chen Zhuo , Niu Hongtao
Published: December 2021

Background The aim of the study is to analyze the effect of multiple punctures in computed tomography (CT)-guided microcoil localization of pulmonary nodules with other risk factors for common complications.

Methods Consecutive patients who underwent CT-guided microcoil localization and subsequent video-assisted thoracoscopic surgery (VATS) between January 2020 and February 2021 were enrolled. Nodules successfully located after only one puncture were defined as the single puncture group, and nodules requiring two or more punctures were defined as the multiple puncture group. Binary logistic regression analysis was performed to assess the relationship between the number of punctures and pneumothorax and intrapulmonary hemorrhage.

Results A total of 121 patients were included. There were 98 (68.1%) pulmonary nodules in the single puncture group compared with 46 (31.9%) nodules in the multiple puncture group. The frequencies of pneumothorax and intrapulmonary hemorrhage were higher in the multiple puncture group than in the single puncture group (p = 0.019 and <0.001, respectively). Binary logistic regression demonstrated that independent risk factors for developing pneumothorax included lateral positioning of the patient (p < .001) and prone positioning (p = 0.014), as well as multiple punctures (p = 0.013). Independent risk factors for intrapulmonary hemorrhage included the distance between the distal end of the coil and the surface of the pleura (p = 0.033), multiple punctures (p = 0.003), and passage through the pulmonary vasculature (p < 0.001).

Conclusion Multiple punctures resulted in an increased incidence of pneumothorax and intrapulmonary hemorrhage compared with single puncture during CT-guided microcoil localization of pulmonary nodules and were independently associated with both pneumothorax and intrapulmonary hemorrhage.
Long-Term Follow-up from the Treatment and Crossover Arms of a Randomized Controlled Trial of an Absorbable Nasal Implant for Dynamic Nasal Valve Collapse
Authors: Bikhazi Nadim , Ow Randall A. , O'Malley Ellen M. , Perkins Nora , Sidle Douglas M. , Stolovitzky Pablo
Published: December 2021

We report the long-term safety and efficacy outcomes of the treatment and crossover arms of a randomized controlled trial evaluating an absorbable nasal implant to address dynamic nasal valve collapse. Participants were adults with severe/extreme nasal airway obstruction primarily due to nasal valve insufficiency who had implant placement. Follow-up visits were at 3, 6, 12, 18, and 24 months post implant. Visits included collection of the following patient-reported outcome measures: nasal obstructive symptom evaluation (NOSE), nasal obstruction visual analog scale (VAS), and the Epworth Sleepiness Scale (ESS). Adverse events were evaluated at each visit. One-hundred-eleven participants with implants were followed. Of the 111, 90 completed the 12-month visit and 70 completed the 24-month visit. NOSE responder rates are greater than 80% at all follow-ups through 24 months. Mean reduction from baseline in NOSE scores is ≥30 points and statistically significant (p <0.001) at all time points through 24 months. Mean VAS score reduction is ≥29.7 points and statistically significant (p <0.001) at all time points. The subgroup of participants with baseline ESS values >10 experienced statistically significant (p <0.001) and clinically meaningful reductions at all postimplant periods, suggesting that the reduction in nasal symptoms may reduce daytime sleepiness for patients who have problems with sleep quality. No serious device-/procedure-related adverse events were reported. Implant migration/retrieval rate was 4.5% (10/222) of total implants or 9% of participants (10/111). The implant is safe and effective for dynamic nasal valve collapse in patients with severe/extreme nasal obstruction and provides durable symptom improvement 24 months after placement.
Factors Related to the Delayed Cure of Hemifacial Spasm after Microvascular Decompression: An Analysis of 175 Consecutive Patients
Authors: Sato Yosuke , Shimizu Katsuyoshi , Iizuka Kazuki , Irie Ryo , Matsumoto Masaki , Mizutani Tohru
Published: December 2021

Detailed studies assessing the factors related to delayed cure of hemifacial spasm (HFS) after microvascular decompression (MVD) are sparse. We aimed to evaluate the effect of 11 clinical factors on the time until the patient became spasm free after MVD. We enrolled 175 consecutive patients with HFS who underwent MVD between 2012 and 2018. The end point was defined as the time point at which the patient became spasm free based on the outpatient interview. Patients were divided into six groups depending on when they became spasm free after the operation, as follows: <7 days (n = 62), 7 days to 1 month (n = 28), 1 to 3 months (n = 38), 3 to 6 months (n = 25), 6 to 12 months (n = 17), and >12 months (n = 5). The median time to become spasm free after MVD was 30.0 days. Association of 11 factors (age, sex, laterality, number of offending arteries, vertebral artery compression, number of compression sites, compression at root detachment zone, preoperative Botox treatment, indentation of the brain stem on preoperative magnetic resonance image, transposition, and interposition) with spasm-free rate was assessed using the Cox's proportional hazards model. Spasm-free rate curve after MVD for the significant factor was obtained using the Kaplan–Meier method. In univariate and multivariate analyses, nontransposition was significantly related to delayed HFS cure after MVD (hazard ratio [HR], 0.60; 95% confidence interval [CI], 0.42, 0.87; p = 0.0068 and HR, 0.60; CI, 0.43, 0.85; p = 0.042, respectively). The spasm-free rate was higher in the transposition than in the nontransposition group (p = 0.0013). As shortening the time until spasm free after MVD improves patients' quality of life, transposition should be recommended. Prediction of spasm-free time could relieve the anxiety of postoperative patients.
Anode power deposition in applied field magnetoplasmadynamic thruster
Authors: Wu Peng , Wang Yibai , Li Yong , Chen Zhiyuan , Zhu Tao , Tang Haibin
Published: December 2021

Applied field magnetoplasmadynamic thrusters (AF-MPDTs) are one of the potential thrusters for high power space propulsion. However, the high anode power deposition limits the improvement in the thruster’s efficiency. According to previous research studies, the anode voltage drop is supposed to be the main factor of the anode power deposition in AF-MPDTs without considering the effect of the centrifugal force. Actually, the centrifugal force cannot be neglected when the magnetic field is high, where the anode voltage drop is not the only dominant factor of the anode power deposition. Due to the significant centrifugal force, there might be no obvious shortage of charge carriers near the anode surface in AF-MPDTs with propellant injection between the cathode and anode. The electrons will be compressed to the anode surface instead of the cathode. In order to investigate the reason for the anode power deposition in AF-MPDTs, a model considering the effect of the centrifugal force is established. The calculated anode power deposition shows good agreement with the corresponding experimental data. In addition, when the magnetic field is high, the viscous heating cannot be neglected, which is as significant as the anode sheath heating and Joule heating. Finally, in order to reduce the anode power deposition, a magnetic field distribution with a high value near the cathode and a low value near the anode is proposed. According to the evaluation by the model, the anode power deposition can be reduced by 30% via the new magnetic field when the magnetic field exceeds 0.1 T.
Optimal efficiency of high-frequency chest wall oscillations and links with resistance and compliance in a model of the lung
Authors: Brunengo Michaël , Mitchell Barrett R. , Nicolini Antonello , Rousselet Bernard , Mauroy Benjamin
Published: December 2021

Chest physiotherapy is a set of techniques used to help the draining of the mucus from the lung in pathological situations. The choice of the techniques and their adjustment to the patients or to the pathologies remain as of today largely empirical. High-frequency chest wall oscillation (HFCWO) is one of these techniques, performed with a device that applies oscillating pressures on the chest. However, there is no clear understanding of how HFCWO devices interact with the lung biomechanics. Hence, we study idealized HFCWO manipulations applied to a mathematical and numerical model of the biomechanics of the lung. The lung is represented by a fluid–structure interaction model based on an airway tree that is coupled to a homogeneous elastic medium. We show that our model is driven by two dimensionless numbers that drive the effect of the idealized HFCWO manipulation on the model of the lung. Our model allows us to analyze the stress applied to an idealized mucus by the air–mucus interaction and by the airway walls deformation. This stress behaves as a buffer and has the effect of reducing the stress needed to overcome the idealized mucus yield stress. Moreover, our model predicts the existence of an optimal range of the working frequencies of HFCWO. This range is in agreement with the frequencies actually used by practitioners during HFCWO maneuvers. Finally, our model suggests that analyzing the mouth airflow during HFCWO maneuvers could allow us to estimate the compliance and the hydrodynamic resistance of the lung of a patient.
Graphene nanostructures for input–output bioelectronics
Authors: Garg Raghav , Roman Daniel San , Wang Yingqiao , Cohen-Karni Devora , Cohen-Karni Tzahi
Published: December 2021

The ability to manipulate the electrophysiology of electrically active cells and tissues has enabled a deeper understanding of healthy and diseased tissue states. This has primarily been achieved via input/output (I/O) bioelectronics that interface engineered materials with biological entities. Stable long-term application of conventional I/O bioelectronics advances as materials and processing techniques develop. Recent advancements have facilitated the development of graphene-based I/O bioelectronics with a wide variety of functional characteristics. Engineering the structural, physical, and chemical properties of graphene nanostructures and integration with modern microelectronics have enabled breakthrough high-density electrophysiological investigations. Here, we review recent advancements in 2D and 3D graphene-based I/O bioelectronics and highlight electrophysiological studies facilitated by these emerging platforms. Challenges and present potential breakthroughs that can be addressed via graphene bioelectronics are discussed. We emphasize the need for a multidisciplinary approach across materials science, micro-fabrication, and bioengineering to develop the next generation of I/O bioelectronics.
Numerical simulation of a confined cavitating gas bubble driven by ultrasound
Authors: Mifsud Jacqueline , Lockerby Duncan A. , Chung Yongmann M. , Jones Gordon
Published: December 2021

This work investigates the flow disturbance generated by an ultrasonically driven gas bubble confined in a narrow gap over one acoustic cycle. Here, we provide a more accurate representation of ultrasonic cleaning by implementing a volume-of-fluid model in OpenFOAM that simulates the ultrasound as a sinusoidally time-varying pressure boundary condition. A modified Rayleigh–Plesset equation is solved to select an acoustic forcing that instigates bubble collapse. Simulations reveal the interaction between the inflow from the acoustic forcing and the flow deflected by the confining walls intensifies the strength of the self-piercing micro-jet(s), and consequently of the unsteady boundary layer flow, compared to the traditional collapse near a single rigid wall. Depending on the gap height and the position of bubble inception inside the gap, three distinct collapse regimes involving dual-jets or directed-jets are identified, each resulting in a different shear-stress footprint on the confining boundaries. Plots of the spatiotemporal evolution of the shear flow (that is difficult to measure experimentally) reveal peak shear-stress magnitudes at collapse that are double those reported for an undriven laser-induced bubble in similar geometric confinement. This twofold increase is attributed to the ultrasonic signal driving the collapse. Surprisingly, in our simulations we have not encountered a transferred-jet regime previously observed for an unforced bubble collapsing in a similar configuration. This unexpected finding highlights the different physics involved in modeling acoustically driven bubbles compared with the conventional laser-induced bubbles used in experiments.
Tunable plasmon–polarizmon resonance and hotspots in metal–silicon core–shell nanostructures
Authors: Nayfeh Ammar , Rezk Ayman , Elhalawany Noha , Al Ruqeishi Majid , Kocyigit Adem , Bahceci Ersin , Nayfeh Munir Hasan
Published: December 2021

Metal nanostructures create near-field super hotspots under light irradiation with a range limited to a few nanometers. The intense field in the spot affords enhanced nonlinear optical processes, such as Raman spectroscopy. The intense field, however, can cause heavy distortion and thermal damage to the molecular specimen as well as heavy convolution with the metal electronic structure. In this work, we simulate concentric layered silicon–metal core–shell (and its inverse) nanostructures that may alleviate the disadvantages of the pure metal environment. Our results using Mie and finite-difference time-domain scattering studies show that, in addition to the super hotspot at the gold–silicon interface, there emerges a super hotspot at the silicon–vacuum interface, whose intensities anti-correlate and are tuned by tuning the silicon thickness. Moreover, the plasmonic resonance red shifts with the thickness of the silicon shell, reaching a terminal wavelength of ∼840 nm. These features are understood in terms of induced polarization charge at the silicon–metal and silicon–vacuum interfaces, which for high κ materials (13.32) can be significant. The metal–silicon system creates plasmon–polarizmon hotspots tunable in strength and wavelength content that can be designed to alleviate high field damage, useful for Raman scattering and photovoltaic applications. The integrated metal–silicon system also promises field enhancement of visible luminescence of silicon nanoparticles, useful for imaging and tracking applications.
Optical Coherence Elastography Techniques
Authors: Chin Lixin , Wijesinghe Philip , Oldenburg Amy L. , Kennedy Brendan F.
Published: December 2021

Tissue mechanical properties determine the relationship between an applied mechanical load and the resulting deformation of the sample. In optical coherence elastography (OCE), the objective is to spatially resolve tissue mechanical properties from often incomplete and noisy measurements of the load and deformation. This is achieved by solving an inverse problem, using a model of elasticity that reasonably describes the behavior of tissue. Incorporating more parameters into the model (such as heterogeneity, anisotropy, nonlinearity, or viscoelasticity) than are needed in a given application can unnecessarily complicate the inverse problem. Also, how the load is applied can enhance certain tissue responses, and the validity of an elasticity model, and, thus, allow for the characterization of tissue in different regimes. A successful OCE technique offers a good match between the load application method, and the tissue mechanical properties of interest, and employs a reasonably complete but simplified mechanical model that provides a noise-robust inversion. OCE techniques can be classified into two broad categories: those inducing and subsequently tracking propagating mechanical waves, and those applying and assuming a uniaxial load, and tracking the deformation in response. With a brief introduction to the former, this chapter focuses on the latter group, describes the most prominent of these techniques, and presents an overview of studies that have successfully extracted mechanical properties in tissue-like media.
WASP integrates substrate topology and cell polarity to guide neutrophil migration
Authors: Brunetti Rachel M. , Kockelkoren Gabriele , Raghavan Preethi , Bell George R.R. , Britain Derek , Puri Natasha , Collins Sean R. , Leonetti Manuel D. , Stamou Dimitrios , Weiner Orion D.
Published: December 2021

To control their movement, cells need to coordinate actin assembly with the geometric features of their substrate. Here, we uncover a role for the actin regulator WASP in the 3D migration of neutrophils. We show that WASP responds to substrate topology by enriching to sites of inward, substrate-induced membrane deformation. Superresolution imaging reveals that WASP preferentially enriches to the necks of these substrate-induced invaginations, a distribution that could support substrate pinching. WASP facilitates recruitment of the Arp2/3 complex to these sites, stimulating local actin assembly that couples substrate features with the cytoskeleton. Surprisingly, WASP only enriches to membrane deformations in the front half of the cell, within a permissive zone set by WASP’s front-biased regulator Cdc42. While WASP KO cells exhibit relatively normal migration on flat substrates, they are defective at topology-directed migration. Our data suggest that WASP integrates substrate topology with cell polarity by selectively polymerizing actin around substrate-induced membrane deformations in the front half of the cell.
Carbon nanotube/glycerol embedded low cost flexible sensor for large deflection sensing of continuum manipulators
Authors: Bhattacherjee Saptak , Chatterjee Sananda , Bhaumik Subhasis
Published: December 2021

Large deflection sensing is highly crucial for proper positioning and control of continuum robots during robot assisted minimally invasive surgery (MIS). Existing techniques suffer from eletromagnetic noise susceptibility, harmful radiation exposure, limited range, bio-incompatibility and necessity of expensive instruments. In the present study, we propose a multi-walled carbon nanotubes/polyglycerol based low cost, flexible and biocompatible sensor which could allow safer, faster and accurate angular deflection measurement of continuum robots for biomedical applications. Experimental results demonstrate that the sensor is stretchable up to 100%, provides a gauge factor up to 11.65, have response time around 8 ms, durability of −0.14% for cyclic loading and unloading and show very small creep up to

±
0.0008
 
(
±
2.88
%
)

. Furthermore, the sensor can measure continuum robot deflection up to

±

150

∘

with a sensitivity of 666.67 ohms/degree, with a maximum error of 1.67% and maximum hysteresis of 1.41%. Thus, wide range, low cost, fast response, and biocompatibility justify the potential of the proposed sensor for large deflection sensing of continuum robots during robot assisted MIS.
Targeted drug delivery vehicles mediated by nanocarriers and aptamers for posterior eye disease therapeutics: barriers, recent advances and potential opportunities
Authors: Zhang Tingting , Jin Xin , Zhang Nan , Jiao Xinyi , Ma Yuanyuan , Liu Rui , Liu Boshi , Li Zheng
Published: December 2021

Nanomedicine and aptamer have excellent potential in giving play to passive and active targeting respectively, which are considered to be effective strategies in the retro-ocular drug delivery system. The presence of closely adjoined tissue structures in the eye makes it difficult to administer the drug in the posterior segment of the eye. The application of nanomedicine could represent a new avenue for the treatment, since it could improve penetration, achieve targeted release, and improve bioavailability. Additionally, a novel type of targeted molecule aptamer with identical objective was proposed. As an emerging molecule, aptamer shows the advantages of penetration, non-toxicity, and high biocompatibility, which make it suitable for ocular drug administration. The purpose of this paper is to summarize the recent studies on the effectiveness of nanoparticles as a drug delivery to the posterior segment of the eye. This paper also creatively looks forward to the possibility of the combined application of nanocarriers and aptamers as a new method of targeted drug delivery system in the field of post-ophthalmic therapy.
‘Why don’t you just tell us what light really is?’ Easy-to-implement teaching materials that link quantum physics to nature of science
Authors: Stadermann Kirsten , Goedhart Martin
Published: December 2021

High school students’ difficulties with quantum physics (QP) are partly due to their limited understanding of the nature of science (NOS). The essence of QP can only be understood with informed views about NOS aspects such as the role of models and the relevance of controversies between physicists. Inversely, QP is an ideal topic for teaching aspects of NOS. However, secondary school textbooks seldom support teachers to explicitly address NOS in QP. Drawing on a five year research program, including observations of students and teachers, we present teaching resources that link NOS aspects with QP. Our materials support active and reflective learning activities, while being adaptable to teachers’ individual needs and affordances. We hope to inspire teachers to address NOS in their QP lessons.
Graphical analysis of the movements of a line-following robot
Authors: Santos Paulo José Sena dos , Vargas Josemar de Siqueira , Cé Amanda Vogel , Perfeito Correia Tiago Fernandes , Dias Weslley de Oliveira , Tiedt Rodrigo Sérgio
Published: December 2021

The difficulties in the interpretation of graphs in kinematics have been studied since the 1980s. To try to reduce students’ learning problems, the researchers point to the need for different didactic strategies, some with the use of new technologies. In this context, we present an experimental proposal that uses a line-following robot based on Arduino to teach graph interpretation in movements with constant velocity.
Actual vs textbook transformers
Authors: Cross Rod
Published: December 2021

The current in the secondary coil of a transformer acts to oppose the flux generated by current in the primary coil, by Lenz’s law. According to most physics textbooks, the total flux is then zero, so transformers should stop working. Something is missing in the textbook accounts.
Biophysical compartment models for single-shell diffusion MRI in the human brain: a model fitting comparison
Authors: Davis Andrew D , Hassel Stefanie , Arnott Stephen R , Hall Geoffrey B , Harris Jacqueline K , Zamyadi Mojdeh , Downar Jonathan , Frey Benicio N , Lam Raymond W , Kennedy Sidney H , Strother Stephen C
Published: December 2021

Clinically oriented studies commonly acquire diffusion MRI (dMRI) data with a single non-zero b-value (i.e. single-shell) and diffusion weighting of b = 1000 s mm−2. To produce microstructural parameter maps, the tensor model is usually used, despite known limitations. Although compartment models have demonstrated improved fits in multi-shell dMRI data, they are rarely used for single-shell parameter maps, where their effectiveness is unclear from the literature. Here, various compartment models combining isotropic balls and symmetric tensors were fitted to single-shell dMRI data to investigate model fitting optimization and extract the most information possible. Full testing was performed in 5 subjects, and 3 subjects with multi-shell data were included for comparison. The results were tested and confirmed in a further 50 subjects. The Markov chain Monte Carlo (MCMC) model fitting technique outperformed non-linear least squares. Using MCMC, the 2-fibre-orientation mono-exponential ball and stick model (

BS

ME

2

) provided artifact-free, stable results, in little processing time. The analogous ball and zeppelin model (

BZ

2

) also produced stable, low-noise parameter maps, though it required much greater computing resources (50 000 burn-in steps). In single-shell data, the gamma-distributed diffusivity ball and stick model (

BS

GD

2

) underperformed relative to other models, despite being an often-used software default. It produced artifacts in the diffusivity maps even with extremely long processing times. Neither increased diffusion weighting nor a greater number of gradient orientations improved

BS

GD

2

fits. In white matter (WM), the tensor produced the best fit as measured by Bayesian information criterion. This result contrasts with studies using multi-shell data. However, in crossing fibre regions the tensor confounded geometric effects with fractional anisotropy (FA): the planar/linear WM FA ratio was 49%, while

BZ

2

and

BS

ME

2

retained 76% and 83% of restricted fraction, respectively. As a result, the

BZ

2

and

BS

ME

2

models are strong candidates to optimize information extraction from single-shell dMRI studies.
Magneto- and electrophosphene thresholds in the retina: a dosimetry modeling study
Authors: Nissi Janita , Laakso Ilkka
Published: December 2021

Objective. Sensations of flickering light produced by time-varying magnetic fields or electric currents are called magneto- or electrophosphenes. Phosphene thresholds have been used in international guidelines and standards as an estimate of the thresholds of exposure that produce effects in the central nervous system (CNS). However, the estimated threshold values have a large range of uncertainty. Approach. Phosphene thresholds were approximated by simulating five phosphene threshold experiments. Retinal electric fields and currents induced by electric and magnetic stimulation were calculated using the finite element method and 14 anatomically realistic computational models of human heads. Main results. The radial component of retinal current density was determined to be in the range of 6.0–20.6 mA m−2. This study produces more accurate estimates for threshold current density in the retina using detailed anatomical models and the estimates had a reduced range of uncertainty compared to earlier studies. Significance. The results are useful for studying the mechanisms of retinal phosphenes and for the development of exposure limits for the CNS.
Bayesian on-line anticipation of critical transitions
Authors: Heßler Martin , Kamps Oliver
Published: December 2021

The design of reliable indicators to anticipate critical transitions in complex systems is an important task in order to detect imminent regime shifts and to intervene at an early stage to either prevent them or mitigate their consequences. We present a data-driven method based on the estimation of a parameterized nonlinear stochastic differential equation that allows for a robust anticipation of critical transitions even in the presence of strong noise which is a characteristic of many real world systems. Since the parameter estimation is done by a Markov chain Monte Carlo approach, we have access to credibility bands allowing for a better interpretation of the reliability of the results. We also show that the method can yield meaningful results under correlated noise. By introducing a Bayesian linear segment fit it is possible to give an estimate for the time horizon in which the transition will probably occur based on the current state of information. This approach is also able to handle nonlinear time dependencies of the parameter that controls the transition. The method can be used as a tool for on-line analysis to detect changes in the resilience of the system and to provide information on the probability of the occurrence of critical transitions in future. Additionally, it can give valuable information about the possibility of noise induced transitions. The discussed methods are made easily accessible via a flexibly adaptable open source toolkit named ‘antiCPy’ which is implemented in the programming language Python.
Reflective and transmissive cross-polarization converter for terahertz wave in a switchable metamaterial
Authors: Jiang Yuanyuan , Zhang Man , Wang Weihua , Song Zhengyong
Published: December 2021

Utilizing the phase transition characteristic of vanadium dioxide, we present a metamaterial configuration to achieve both reflective and transmissive cross-polarization converters. When vanadium dioxide is metal, the design behaves as a reflective cross-polarization converter. It consists of metallic grating, topas spacer, and vanadium dioxide film. Polarization conversion ratio is more than 90% in the frequency range from 4.80 THz to 13.13 THz. When vanadium dioxide is insulator, the design behaves as a transmissive cross-polarization converter using cascaded metallic gratings with rotation angle 45°. High-efficiency broadband cross-polarization wave conversion is achieved in the frequency band of 0.50–4.75 THz. Effect of oblique incidence is studied on polarization conversion. Results tell that cross-polarization conversion is better when incident angle is in the range of 0°–40°. The designed metamaterial may have a certain inspiration for the research of terahertz multifunctional polarization converter.