bluuebunny/crossref_metadata_2025 huggingface dataset:
Added value of hybrid SPECT with CT imaging for predicting poor therapeutic efficacy of 89Sr in patients with bone metastasis
Authors: Meng Ben , Song Jia , Liu Lisheng , Chen Longlan , Chen Xiaoliang
Published: December 2020

To utilize single-photon emission computed tomography/computed tomography (SPECT/CT) scanning to investigate the usefulness of nerve root compression (NRC) and radioactive cold zone lesions (RCZLs) for predicting poor therapeutic efficacy of strontium-89 chloride (Sr-89) in patients with bone metastasis. Patients with bone metastatic neoplasms who had undergone baseline bone SPECT/CT scanning before Sr-89 therapy (148 MBq Sr-89 chloride by an intravenous injection for each patient) between July 2011 and July 2018 were included. Bone SPECT/CT images were assessed by two readers independently. Associations between imaging features and therapeutic efficacy were obtained via multivariate logistic regression analysis. Of 231 patients analyzed, 50 (21.6%) had NRC at baseline. Of 31 patients who experienced poor therapeutic efficacy, 29 (93.5%) had NRC. In multivariate logistic regression analysis baseline NRC independently predicted poor therapeutic efficacy. The sensitivity of NRC for predicting poor therapeutic efficacy was 93.5%, specificity was 89.5%, positive predictive value was 58.0%, and negative predictive value was 98.9%. RCZLs were detected in17 patients (7.4%), of whom 14 experienced poor Sr-89 therapeutic efficacy. The sensitivity of the presence of RCZLs for predicting poor therapeutic efficacy was 45.2%, specificity was 98.5%, positive predictive value was 82.4%, and negative predictive value was 92.1%. After adjusting for age, bone metabolism and lesion type, the significant independent predictors of poor Sr-89 therapeutic efficacy were presence of NRC (p < 0.001) and RCZL (p = 0.001). NRC and RCZL on baseline bone SPECT/CT are reliable independent predictors of poor Sr-89 therapeutic efficacy in patients with bone metastasis. These associations may facilitate the administration of more effective therapeutic interventions.
Augmented transcripts of kidney injury markers and renin angiotensin system in urine samples of overweight young adults
Authors: Rivera Patricia , Miranda Catalina , Roldán Nicole , Guerrero Aaron , Olave Javier , Cárdenas Pilar , Nguyen Quynh My , Kassan Modar , Gonzalez Alexis A.
Published: December 2020

Obesity has been firmly established as a major risk factor for common disease states including hypertension, type 2 diabetes mellitus, and chronic kidney disease. Increased body mass index (BMI) contributes to the activation of both the systemic and intra-tubular renin angiotensin systems (RAS), which are in turn associated with increased blood pressure (BP) and kidney damage. In this cross-sectional study, 43 subjects of normal or increased body weight were examined in order to determine the correlation of BMI or body fat mass (BFM) with blood pressure, fasting blood glucose (FBG), and urinary kidney injury markers such as interleukin-18 (IL-18), connective tissue growth factor (CTGF), neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1 (KIM-1). Our results showed that: (1) subjects with increased body weight showed significantly higher BP, BFM, total body water and metabolic age; (2) BMI was positively correlated to both systolic (R2 = 0.1384, P = 0.01) and diastolic BP (R2 = 0.2437, P = 0.0008); (3) BFM was positively correlated to DBP (R2 = 0.1232, P = 0.02) and partially correlated to urine protein (R2 = 0.047, P = 0.12) and FBG (R2 = 0.07, P = 0.06); (4) overweight young adults had higher urinary mRNA levels of renin, angiotensinogen, IL-18 and CTGF. These suggest that BMI directly affects BP, kidney injury markers, and the activation of the intra-tubular RAS even in normotensive young adults. Given that BMI measurements and urine analyses are non-invasive, our findings may pave the way to developing a new and simple method of screening for the risk of chronic kidney disease in adults.
Effects of long-term antibiotic treatment on mice urinary aromatic amino acid profiles
Authors: Zhu Xuehang , Fu Bin , Dong Manyuan , Guo Yangyang , Cao Zheng , Wu Junfang
Published: December 2020

The gut microbiota–host co-metabolites are good indicators for representing the cross-talk between host and gut microbiota in a bi-direct manner. There is increasing evidence that levels of aromatic amino acids (AAAs) are associated with the alteration of intestinal microbial community though the effects of long-term microbial disturbance remain unclear. Here we monitored the gut microbiota composition and host–microbiota co-metabolites AAA profiles of mice after gentamicin and ceftriaxone treatments for nearly 4 months since their weaning to reveal the relationship between host and microbiome in long- term microbial disturbances. The study was performed employing targeted LC-MS measurement of AAA-related metabolites and 16S RNA sequence of mice cecal contents. The results showed obvious decreased gut microbial diversity and decreased Firmicutes/Bacteroidetes ratio in the cecal contents after long-term antibiotics treatment. The accumulated AAA (tyrosine, phenylalanine and tryptophan) and re-distribution of their downstreaming metabolites that produced under the existence of intestinal flora were found in mice treated with antibiotics for 4 months. Our results suggested that the long-term antibiotic treatment significantly changed the composition of the gut microbiota and destroyed the homeostasis in the intestinal metabolism. And the urinary AAA could be an indicator for exploring interactions between host and gut microbiota.
Variations in Hyoid Kinematics Across Liquid Consistencies in Healthy Swallowing
Authors: Smaoui Sana , Peladeau-Pigeon Melanie , Steele Catriona M.
Published: December 2020

Purpose

Judgments regarding hyoid movement are frequently included in evaluations of swallowing. However, the literature lacks reference values for measures of hyoid kinematics in healthy swallowing. This study explores hyoid movement across the continuum from thin to extremely thick liquids.

Method

Participants were 39 healthy adults under the age of 60 years (19 men) who underwent videofluoroscopy involving three sips each of 20% w/v thin barium and six sips each of slightly, mildly, moderately, and extremely thick barium. Half of the thickened stimuli were prepared using xanthan gum; and half, with a starch-based thickener. Sip volume was derived from pre- and post-sip cup weights. Hyoid position was tracked frame-by-frame relative to the anterior–inferior corner of C4. Measures of peak hyoid position (along the
XY
axis) were normalized to a C2–C4 scalar, and measures of time-to-peak position, speed, and time-to-peak speed were derived. As a first step, Spearman's correlations confirmed the influence of sip volume on these hyoid measures. Linear mixed-effects models then explored the effects of stimulus, sip volume, and task repetition on the dependent variables.

Results

The data set comprised 975 swallows with available hyoid tracking data. Sip volume was correlated with peak hyoid
XY
position (

r
s

= .15,
p
< .01), time-to-peak position (

r
s

= −.15,
p
< .05), and speed (

r
s

= .13,
p
< .01). No significant differences in hyoid kinematics were found across stimuli.

Conclusion

Measures of hyoid movement in healthy swallowing remain stable across the range from thin to extremely thick liquids with no systematic alterations in hyoid position or kinematics.
Tailoring Effective Behavior Management Strategies for Speech-Language Pathologists
Authors: Chow Jason C. , Zimmerman Kathleen N. , Senter Reed
Published: December 2020

Purpose

Many speech-language pathologists (SLPs) experience challenging behaviors during service delivery and also report minimal training in effective behavior management strategies. The purpose of this tutorial is to present low-effort behavior management strategies that SLPs can adopt, adapt, and implement.

Method

After providing an overall rationale for effective behavior management strategies, we present two evidence-based behavior management strategies aimed at improving positive behavior and engagement. We provide descriptions, steps, and applied examples for implementing visual activity schedules and behavior-specific praise. We include three implementation scenarios and resources for SLPs to access specifically tailored to speech-language pathology practice.

Conclusions

Visual activity schedules and behavior-specific praise are two flexible behavior management strategies that can be collaboratively created by SLPs and educators and implemented during a variety of instructional arrangements during speech and language therapy. Implementing evidence-based behavior management strategies may improve students' engagement and achievement in speech and language-focused outcomes.
Psychosocial Adversity in Early Childhood and Language and Literacy Skills in Adolescence: The Role of Speech-Language Pathology in Prevention, Policy, and Practice
Authors: Snow Pamela C.
Published: December 2020

Purpose

This clinical focus article outlines key forms of childhood maltreatment (various types of abuse and neglect) and their co-occurrence with other developmental risk factors, such as parental poverty, living in crime-prone communities, and disrupted educational experiences, to focus on their implications for language and literacy skills in adolescence. Children exposed to psychosocial adversity early in life experience a range of poor outcomes in adolescence, relative to their typically developing peers, and language and literacy skills are particularly vulnerable skill sets in the face of this adversity.

Conclusions

The continuum from disrupted schooling to child protection and youth justice involvement is emphasized, and the expanding scope of practice for speech-language pathology at all stages of prevention, assessment, and intervention is outlined. Greater advocacy by speech-language pathologists is needed so that policy makers and practitioners in other service sectors have a better appreciation of the importance of language and literacy skills in early life.
Cyber‐physical reliability of dynamic line rating ICT failures in OHL networks
Authors: Kopsidas K. , Cruzat C. , Ni M.
Published: December 2020

The integration of information and communication technologies in power networks enables greater flexibility through Smart Grids and increased network adequacy and reliability. Information and communication technology's functionality and design diversity within the cyber‐physical power system should be explicitly defined to quantify the risk of information and communication technology failures. The purpose of this paper is to quantify the cyber‐physical reliability risk introduced by the information and communication technology deployed for dynamic line rating implementations, which are usually installed in adverse environments and have a higher failure risk than indoor information and communication technology installations. This cyber‐physical reliability study employs a modified sequential Monte Carlo approach with a Markov state space to capture the dynamic line rating‐information and communication technology functionality. The method integrates the additional dynamic line rating states within the overhead line operating states, which allows quantifying the risk of dynamic line rating failures against the risk of traditional probabilistic line rating uprating practices. Results from IEEE 24‐bus and 14‐bus network reliability studies indicate that dynamic line rating‐information and communication technology failures (a) increase generation costs in the 24‐bus transmission network with high generation flexibility, while (b) they reduce the reliability of the 14‐bus network with small generation diversity and multiple load points. Such results can provide insightful recommendations on the quality of dynamic line rating‐information and communication technology infrastructure and inform utility's investment planning processes and maintenance practices.
An effective weighted vector median filter for impulse noise reduction based on minimizing the degree of aggregation
Authors: Meng Xiangxi , Lu Tongwei , Min Feng , Lu Tao
Published: December 2020

Impulse noise is regarded as an outlier in the local window of an image. To detect noise, many proposed methods are based on aggregated distance, including spatially weighted aggregated distance, n nearest neighbour distance, local density, and angle‐weighted quaternion aggregated distance. However, these methods ignore the weight of each pixel or have limited adaptability. This study introduces the concept of degree of aggregation and proposes a weighting method to obtain the weight vector of the pixels by minimizing the degree of aggregation. The weight vector obtained gives larger components on the signal pixels than on the noisy pixels. Then it is fused with the aggregated distance to form a weighted aggregated distance that can reasonably characterise the noise and signal. The weighted aggregated distance, along with an adaptive segmentation method, can effectively detect the noise. To further enhance the effect of noise detection and removal, an adaptive selection strategy is incorporated to reduce the noise density in the local window. At last, noisy pixels detected are replaced with the weighted channel combination optimization values. The experimental results exhibit the validity of the proposed method by showing better performance in terms of both objective criteria and visual effects.
The effect of a dynamo-generated field on the Parker wind
Authors: Jakab P. , Brandenburg A.
Published: December 2020

Context.Stellar winds are an integral part of the underlying dynamo, the motor of stellar activity. The wind controls the star’s angular momentum loss, which depends on the magnetic field geometry which, in turn, varies significantly in time and latitude.

Aims.Here we study basic properties of a self-consistent model that includes simple representations of both the global stellar dynamo in a spherical shell and the exterior in which the wind accelerates and becomes supersonic.

Methods.We numerically solved an axisymmetric mean-field model for the induction, momentum, and continuity equations using an isothermal equation of state. The model allows for the simultaneous generation of a mean magnetic field and the development of a Parker wind. The resulting flow is transonic at the critical point, which we arranged to be between the inner and outer radii of the model. The boundary conditions are assumed to be such that the magnetic field is antisymmetric about the equator, that is to say dipolar.

Results.At the solar rotation rate, the dynamo is oscillatory and ofα2type. In most of the domain, the magnetic field corresponds to that of a split monopole. The magnetic energy flux is largest between the stellar surface and the critical point. The angular momentum flux is highly variable in time and can reach negative values, especially at midlatitudes. At a rapid rotation of up to 50 times the solar value, most of the magnetic field is lost along the axis within the inner tangential cylinder of the model.

Conclusions.The model reveals unexpected features that are not generally anticipated from models that are designed to reproduce the solar wind: highly variable angular momentum fluxes even from just anα2dynamo in the star. A major caveat of our isothermal models with a magnetic field produced by a dynamo is the difficulty to reach small enough plasma betas without the dynamo itself becoming unrealistically strong inside the star.
Health Claims für Lebensmittel – Was geschieht mit den Botanicals?
Authors: Armbrüster Nicole
Published: December 2020

Mit der Health-Claims-Verordnung sollte ein europaweit einheitlicher Rechtsrahmen geschaffen werden, um den Verbraucher vor unbelegten und nicht genehmigten gesundheitsbezogenen Angaben über Lebensmittel zu schützen. Eine von der EU-Kommission durchgeführte Evaluierung zeigt nun deutlich, dass der Verbraucherschutz noch immer gegen Null geht, denn die Bewertung der gesundheitsbezogenen Angaben zu pflanzlichen Stoffen in Lebensmitteln ist bis heute ausgesetzt. Die Einführung „traditioneller Health Claims“ kann hier keine Lösung darstellen, sondern würde die Zukunft traditioneller pflanzlicher Arzneimittel gefährden. Geltendes EU-Recht muss endlich umgesetzt werden.
Methoxyfluran beim traumaassoziierten Schmerz – Fallberichte und Literaturüberblick
Authors: Bowl Marianne , Mann Valesco , Martens Florian , Marx Frank , Sander Michael , Little Simon
Published: December 2020

Um den Handlungsspielraum bei der Versorgung von traumainduzierten Akutschmerzen für das ärztliche und nichtärztliche Rettungsdienstpersonal zu erweitern, etablierten wir einen Algorithmus zur Versorgung von traumainduzierten Akutschmerzen. Das seit 2018 in Deutschland zugelassene Methoxyfluran (Penthrox) verwenden wir als Analgetikum für mittelstarke bis starke Schmerzen bei Erwachsenen ohne Bewusstseinseinschränkung. Methoxyfluran ist selbst titrierend, schnell anflutend, inhalativ, nebenwirkungsarm. Neben einem Literaturüberblick über die jahrzehntelange Erfahrung mit dessen prähospitalem Einsatz im Ausland werden 2 Fallbeispiele aus unserer klinischen Praxis vorgestellt. Methoxyfluran ist ein Nichtopioid und kann von geschultem nichtärztlichen Rettungsdienstpersonal angewendet werden. Die Applikationsform ermöglicht eine Schmerztherapie ohne Zeitverlust, bis ein intravenöser Zugang für eine additive Therapie etabliert wird.
24-Stunden-Luftrettung in Baden-Württemberg – Ergebnisse der ersten 12 Monate
Authors: Merz Sabine , Dörges Volker , Reifferscheid Florian
Published: December 2020

Im Jahr 2017 wurde die Luftrettung in Baden-Württemberg durch die Implementierung eines Dual-Use-Rettungshubschraubers 24/7 ergänzt. Im Oktober 2017 erhielt der Luftrettungsstandort Christoph 11 in Villingen-Schwenningen die Beauftragung. Dies war nur unter Einhaltung abgestimmter und angepasster Verfahren möglich, die insbesondere für den Nachtflug notwendig waren. Die Arbeit zeigt Ergebnisse der ersten 12 Monate hinsichtlich der Einsatzindikationen und der Anforderung durch die Leitstellen sowie dem Einsatzaufkommen am Tag und in der Nacht. Ebenso wird die Bedeutung zeitgerechter Alarmierung und Versorgung von Notfallpatienten durch die Luftrettung in der Nacht beschrieben.
Wirksamkeit von Phytotherapeutika in der psychiatrischen Behandlung
Authors: Anheyer Dennis , Haller Heidemarie , Klose Petra , Schröter Marleen , Dobos Gustav , Cramer Holger
Published: December 2020

Hintergrund: Der Einsatz von Phytotherapeutika hat in den letzten Jahren auch in der Behandlung psychiatrischer Erkrankungen erheblich an Bedeutung gewonnen.

Methodik: Dieser narrative Überblick fasst die bisherige Evidenzlage zu Wirkungen und Nebenwirkungen pflanzlicher Arzneimittel bei der Behandlung von depressiven Störungen, Angstzuständen, Schlafstörungen und Hyperaktivitäts- und Aufmerksamkeitsstörungen auf Basis von Metaanalysen und systematischen Übersichtsarbeiten zusammen.

Ergebnisse: Bei der Behandlung von leichten bis mittelschweren depressiven Episoden ist Johanniskraut evidenzbasiert und gut verträglich. Wechselwirkungen mit anderen Medikamenten sollten unbedingt beachtet werden. Für andere Phytotherapeutika ist die Datenlage bisher weniger ausreichend, um konkrete Aussagen treffen zu können.

Schlussfolgerungen: Phytotherapeutika stellen in der Behandlung psychiatrischer Erkrankungen möglicherweise eine gute Alternative oder Ergänzung zu konventionellen Psychopharmaka dar. Sie sind im Vergleich oft nebenwirkungsärmer, gut verträglich und haben eine große therapeutische Breite. Weitere randomisiert kontrollierte Studien sind allerdings dringend indiziert.
Familien mit Kindern psychisch kranker Eltern: Ein Überblick über ambulante, familienorientierte Komplexangebote im deutschsprachigen Raum
Authors: Pohl Sina , Carvalho Fernando Silvia , Leggemann Michael , Driessen Martin
Published: December 2020

Ziel Ziel der vorliegenden Übersichtsarbeit ist es, alle im deutschsprachigen Raum bekannten ambulanten, familienorientierten Komplexangebote für Kinder psychisch kranker Eltern anhand definierter Minimalanforderungen zu identifizieren und einen Überblick über deren Struktur, Inhalt und Wirksamkeitsnachweise zu geben.

Methodik Die Angebote wurden mittels Internet- und Literaturrecherche identifiziert. Bei Erfüllung der definierten Kriterien, wurden die Anbieter kontaktiert und um die Teilnahme an einer schriftlichen oder telefonischen Befragung gebeten.

Ergebnisse Insgesamt konnten 512 Angebote identifiziert werden, von denen 46 als familienorientiertes Komplexangebot einzustufen waren. Nur wenige Angebote wurden bisher systematisch evaluiert.

Schlussfolgerung Es besteht eine Vielzahl an Interventionen für die Kinder psychisch kranker Eltern, familienorientierte Komplexangebote sind jedoch bisher selten. Zudem besteht ein erheblicher Bedarf an Evaluationsstudien.
Synthesis of Indolo[1,2-a]quinoxalinones through Palladium/Copper-Cocatalyzed Oxidative Isocyanide-Insertion Cyclization of Indoles and Hydrolysis of Enamines
Authors: Sha Xuan , Ren Jie , Ji Fei , Hu Yi-ran , Zhao Yun-yi , Wu Shi-ying , Yang Rui , Chen Yao
Published: December 2020

A novel Pd/Cu-cocatalyzed isocyanide-insertion cyclization of indoles and hydrolysis of enamines has been developed for the construction of indolo[1,2-a]quinoxalinones. A secondary amine group on the N-phenylindole skeleton acts as an important directing groups that participates in activation of the C(2)-position of the indole and the subsequent isocyanide-insertion cyclization. The fragile generated enamine bond is easily hydrolyzed by the acid medium to give the corresponding quinoxalinone skeleton. This regioselective and high-yielding transformation, which avoids the use of hazardous CO gas, might be extendable to syntheses of natural polycyclic products.
Ambulatory Clinician's Guide to Inpatient Service: An Innovative Rapid Onboarding Strategy for the COVID-19 Pandemic
Authors: Altman Richard L. , Anstett Tyler , Simpson Jennifer R. , Del Pino-Jones Amira , Lin Chen-Tan , Pell Jonathan
Published: December 2020

Background and Significance When hospitals are subject to prolonged surges in patients, such as during the coronavirus disease 2019 (COVID-19) pandemic, additional clinicians may be needed to care for the rapid increase of acutely ill patients. How might we quickly prepare a large number of ambulatory-based clinicians to care for hospitalized patients using the inpatient workflow of the electronic health record (EHR)?

Objectives The aim of the study is to create a successful training intervention which prepares ambulatory-based clinicians as they transition to inpatient services.

Methods We created a training guide with embedded videos that describes the workflow of an inpatient clinician. We delivered this intervention via an e-mail hyperlink, a static hyperlink inside of the EHR, and an on-demand hyperlink within the EHR.

Results In anticipation of the first peak of inpatients with COVID-19 in April 2020, the training manual was accessed 261 times by 167 unique users as clinicians anticipated being called into service. As our institution has not yet needed to deploy ambulatory-based clinicians for inpatient service, usage data of the training document is still pending.

Conclusion We intend that our novel implementation of a multimedia, highly accessible onboarding document with access from points inside and outside of the EHR will improve clinician performance and serve as a helpful example to other organizations during the COVID-19 pandemic and beyond.
Post-Cesarean Opioid Use after Implementation of Enhanced Recovery after Surgery Protocol
Authors: MacGregor Caitlin A. , Neerhof Mark , Sperling Mary J. , Alspach David , Plunkett Beth A. , Choi Alexandria , Blumenthal Rebecca
Published: December 2020

Objective This study aimed to evaluate whether implementation of an enhanced recovery after surgery (ERAS) protocol is associated with lower maternal opioid use after cesarean delivery (CD).

Study Design We performed a pre- and postimplementation (PRE and POST, respectively) study of an ERAS protocol for cesarean deliveries. ERAS is a multimodal, multidisciplinary perioperative approach. The four pillars of our protocol include education, pain management, nutrition, and early ambulation. Patients were counseled by their outpatient providers and given an educational booklet. Pain management included gabapentin and acetaminophen immediately prior to spinal anesthesia. Postoperatively patients received scheduled acetaminophen and ibuprofen. Oxycodone was initiated as needed 24 hours after spinal analgesia. Preoperative diet consisted of clear carbohydrate drink consumed 2 hours prior to scheduled operative time with advancement as tolerated immediately postoperation. Women with a body mass index (BMI) <40 kg/m2 and scheduled CD were eligible for ERAS. PRE patients were randomly selected from repeat cesarean deliveries (RCDs) at a single site from October 2017 to September 2018, BMI <40 kg/m2, without trial of labor. The POST cohort included women who participated in ERAS from October 2018 to June 2019. PRE and POST demographic and clinical characteristics were compared. Primary outcome was total postoperative morphine milligram equivalents (MMEs). Secondary outcomes included length of stay (LOS) and maximum postoperative day 2 (POD2) pain score.

Results All women in PRE (n = 70) had RCD compared with 66.2% (49/74) in POST. Median total postoperative MMEs were 140.0 (interquartile range [IQR]: 87.5–182.5) in PRE compared with 0.0 (IQR: 0.0–72.5) in POST (p < 0.001). Median LOS in PRE was 4.02 days (IQR: 3.26–4.27) compared with 2.37 days (IQR: 2.21–3.26) in POST (p < 0.001). Mean maximum POD2 pain score was 5.28 (standard deviation [SD] = 1.86) in PRE compared with 4.67 (SD = 1.63) in POST (p = 0.04).

Conclusion ERAS protocol was associated with decreased postoperative opioid use, shorter LOS, and decreased pain after CD.

Key Points
Will Remdesivir Reshape Cardiovascular Practice in COVID 19 Era?
Authors: Idhrees A. Mohammed , Suthakaran Prasanna Karthik , Valooran George Jose , Bashir Mohamad
Published: December 2020

Infection with the novel coronavirus, SARS-CoV2, produces the clinical syndrome COVID-19. COVID-19 is a systemic illness inducing hyperinflammation and cytokine storm affecting multiple organs including the myocardium which is reflected in elevated cardiac biomarkers such as troponin, lactate dehydrogenase, and creatinine kinase MB. Furthermore, COVID-19 has been implicated in increased predilection to thromboembolic phenomena. Hence, mortality in patients with associated cardiovascular disease has been higher compared with the cohort with no cardiovascular comorbidity. It is entirely unknown how remdesivir will change the facet of cardiovascular medicine and surgery. In the present constantly changing climate, this review of remdesivir and its association with cardiovascular disease is comprehensive as of June 17, 2020 and it highlights the science behind this drug and its potential implications to cardiovascular practice.
A high temperature dual-mode quartz crystal microbalance technique for erosion and thermal desorption spectroscopy measurements
Authors: Stadlmayr Reinhard , Szabo Paul Stefan , Biber Herbert , Koslowski Hans Rudolf , Kadletz Elisabeth , Cupak Christian , Wilhelm Richard Arthur , Schmid Michael , Linsmeier Christian , Aumayr Friedrich
Published: December 2020

An improved quartz crystal microbalance measurement method is described, which allows us to determine erosion, implantation, and release rates of thin films, during changing temperatures and up to 700 K. A quasi-simultaneous excitation of two eigenmodes of the quartz resonator is able to compensate for frequency drifts due to temperature changes. The necessary electronics, the controlling behavior, and the dual-mode temperature compensation are described. With this improved technique, quantitative in situ temperature-programmed desorption measurements are possible and the quartz crystal microbalance can be used for quantification of thermal desorption spectroscopy measurements with a quadrupole mass spectrometer. This is demonstrated by a study of the retention and release behavior of hydrogen isotopes in fusion-relevant materials. We find that more than 90% of the deuterium implanted into a thin film of beryllium is released during a subsequent temperature ramp up to 500 K.
A novel four-step feedback procedure for rapid control of chaotic behavior of the logistic map and unstable traffic on the road
Authors: Kumari S. , Chugh R.
Published: December 2020

We present a new four-step feedback procedure to study the full dynamics of a nonlinear dynamical system, namely, the logistic map. We show that by using this procedure, the chaotic behavior of the logistic map can be controlled easily and rapidly or the system can be made stable for higher values of the population growth parameter. We utilize various dynamical techniques (orbit evolution, time series analysis, bifurcation diagrams, and Lyapunov exponents) to analyze the dynamics of the logistic map. Additionally, we adopt the switching strategy to control chaos or to increase the stability performance of the logistic map. Finally, we propose a modified traffic control model to enable rapid control of unexpected traffic on the road. The results of this model are supported by a physical interpretation. The model is found to be more efficient than existing models of Lo and Cho [J. Franklin Inst. 342, 839–851 (2005)] and Ashish et al. [Nonlinear Dyn. 94, 959–975 (2018)]. This work provides a novel feedback procedure that facilitates rapid control of chaotic behavior and increases the range of stability of dynamical systems.
Topological materials by molecular beam epitaxy
Authors: Brahlek Matthew , Lapano Jason , Lee Joon Sue
Published: December 2020

Topology appears across condensed matter physics to describe a wide array of phenomena which could alter, augment, or fundamentally change the functionality of many technologies. Linking the basic science of topological materials to applications requires producing high-quality thin films. This will enable combining dissimilar materials while utilizing dimensionality, symmetry, and strain to create or control the electronic phase, as well as platforms to fabricate novel devices. Yet, one of the longstanding challenges in the field remains understanding and controlling the basic material properties of epitaxial thin films. The aim of this Perspective article is to discuss how understanding the fundamental properties of topological materials grown by molecular beam epitaxy (MBE) is key to deepening the knowledge of the basic physics, while developing a new generation of topological devices. A focus will be on the MBE growth of intrinsic materials, creation, and control of superconducting and magnetic topological phases. Addressing these questions in the coming decade will undoubtedly uncover many surprises as new materials are discovered and their growth as high-quality thin films is refined.
Reconstruction and uncertainty quantification of lattice Hamiltonian model parameters from observations of microscopic degrees of freedom
Authors: Valleti Mani , Vlcek L. , Ziatdinov Maxim , Vasudevan Rama K. , Kalinin Sergei V.
Published: December 2020

The emergence of scanning probe and electron beam imaging techniques has allowed quantitative studies of atomic structure and minute details of electronic and vibrational structure on the level of individual atomic units. These microscopic descriptors, in turn, can be associated with local symmetry breaking phenomena, representing the stochastic manifestation of the underpinning generative physical model. Here, we explore the reconstruction of exchange integrals in the Hamiltonian for a lattice model with two competing interactions from observations of microscopic degrees of freedom and establish the uncertainties and reliability of such analysis in a broad parameter-temperature space. In contrast to other approaches, we specifically specify a loss function inherent to thermodynamic systems and utilize it to estimate uncertainty in simulated realizations of different models. As an ancillary task, we develop a machine learning approach based on histogram clustering to predict phase diagrams efficiently using a reduced descriptor space. We further demonstrate that reconstruction is possible well above the phase transition and in the regions of parameter space when the macroscopic ground state of the system is poorly defined due to frustrated interactions. This suggests that this approach can be applied to the traditionally complex problems of condensed matter physics such as ferroelectric relaxors and morphotropic phase boundary systems, spin and cluster glasses, and quantum systems once the local descriptors linked to the relevant physical behaviors are known.
Characterizing the optical response of ultra-low-noise far-infrared 60–110 μm transition edge sensors
Authors: Williams E. A. , Withington S. , Goldie D. J. , Thomas C. N. , Ade P. A. R. , Sudiwala R.
Published: December 2020

Far-infrared Transition Edge Sensors (TESs) are being developed for the SAFARI grating spectrometer on the cooled-aperture space telescope SPICA. In support of this work, we have devised a cryogenic (90 mK) test facility for carrying out precision optical measurements on ultra-low-noise TESs. Although our facility is suitable for the whole of the SAFARI wavelength range, 34 µm–230 µm, we focus on a representative set of measurements at 60 µm–110 µm using a device having a noise equivalent power of 0.32 aW Hz−1/2. The system is able to perform a range of measurements: (i) dark electrical characterization, (ii) optical efficiency with respect to a partially coherent beam having a modal composition identical to that of an ideal imaging telescope, (iii) optical saturation and dynamic range, (iv) fast optical transient response to a modulated thermal source, and (v) optical transient response in the presence of high-level background loading. We describe dark measurements to determine the operating characteristics of a TES and then compare the predicted optical behavior with the measured optical behavior. By comparing electrical and optical transient responses, we were able to observe thermalization in the device. We comment on the challenge of eliminating stray light.
Generalized mode-coupling theory of the glass transition. II. Analytical scaling laws
Authors: Luo Chengjie , Janssen Liesbeth M. C.
Published: December 2020

Generalized mode-coupling theory (GMCT) constitutes a systematically correctable, first-principles theory to study the dynamics of supercooled liquids and the glass transition. It is a hierarchical framework that, through the incorporation of increasingly many particle density correlations, can remedy some of the inherent limitations of the ideal mode-coupling theory (MCT). However, despite MCT’s limitations, the ideal theory also enjoys several remarkable successes, notably including the analytical scaling laws for the α- and β-relaxation dynamics. Here, we mathematically derive similar scaling laws for arbitrary-order multi-point density correlation functions obtained from GMCT under arbitrary mean-field closure levels. More specifically, we analytically derive the asymptotic and preasymptotic solutions for the long-time limits of multi-point density correlators, the critical dynamics with two power-law decays, the factorization scaling laws in the β-relaxation regime, and the time-density superposition principle in the α-relaxation regime. The two characteristic power-law-divergent relaxation times for the two-step decay and the non-trivial relation between their exponents are also obtained. The validity ranges of the leading-order scaling laws are also provided by considering the leading preasymptotic corrections. Furthermore, we test these solutions for the Percus–Yevick hard-sphere system. We demonstrate that GMCT preserves all the celebrated scaling laws of MCT while quantitatively improving the exponents, rendering the theory a promising candidate for an ultimately quantitative first-principles theory of glassy dynamics.
Deciphering chaos in evolutionary games
Authors: Mukhopadhyay Archan , Chakraborty Sagar
Published: December 2020

A discrete-time replicator map is a prototype of evolutionary selection game dynamical models that have been very successful across disciplines in rendering insights into the attainment of the equilibrium outcomes, like the Nash equilibrium and the evolutionarily stable strategy. By construction, only the fixed-point solutions of the dynamics can possibly be interpreted as the aforementioned game-theoretic solution concepts. Although more complex outcomes like chaos are omnipresent in nature, it is not known to which game-theoretic solutions they correspond. Here, we construct a game-theoretic solution that is realized as the chaotic outcomes in the selection monotone game dynamic. To this end, we invoke the idea that in a population game having two-player–two-strategy one-shot interactions, it is the product of the fitness and the heterogeneity (the probability of finding two individuals playing different strategies in the infinitely large population) that is optimized over the generations of the evolutionary process.
Transitions between electron emission and gas breakdown mechanisms across length and pressure scales
Authors: Garner Allen L. , Meng Guodong , Fu Yangyang , Loveless Amanda M. , Brayfield Russell S. , Darr Adam M.
Published: December 2020

This Perspective outlines theoretical, simulation, and experimental studies linking electron emission and gas breakdown. Many studies have investigated field emission-driven microscale gas breakdown, including recent reviews [Garner et al., IEEE Trans. Plasma Sci. 48, 808–824 (2020); Fu et al., Plasma Res. Express 2, 013001 (2020)]. This Perspective focuses on generalizing field emission-driven microscale gas breakdown to consider the contribution of other forms of electron emission, specifically thermionic and space-charge limited. Recent theoretical studies have unified thermionic, field, and space-charge limited emission with and without collisions to derive “nexuses” where the individual solutions match, indicating transitions in the mechanisms. Reducing device size to nanoscale at atmospheric pressure leads to a transition from field emission to space-charge limited emission for nitrogen at ∼250 nm. This Perspective summarizes the derivation of these nexuses and future extensions. We next describe simulation and theoretical studies for field emission-driven microscale gas breakdown and highlight how the nexus theory may be integrated to account for temperature, space-charge, and pulse parameters. Finally, we summarize the development of optical techniques to assess microscale gas breakdown and recent nanoscale experiments at atmospheric pressure that suggest that space-charge may begin to contribute to field emission prior to gas breakdown. We highlight the combination of theory, simulation, and experiment to link electron emission and gas breakdown mechanisms across length, pressure, and temperature scales for applications that include vacuum electronics, pulsed power, and medicine.
A transient electromagnetic disturbance testing system based on low-frequency-compensated symmetric TEM horn antenna
Authors: Zhou Yi , Xie Yan-zhao , Wang Shao-fei , Zhang Dao-zhong , Yang Jie
Published: December 2020

A transient electromagnetic disturbance (TED) testing system with an adjustable direction of polarization is developed in terms of a low-frequency-compensated symmetric transverse electromagnetic (TEM) horn antenna in this paper. TEM horn antennas are deficient in the low-frequency radiation, which would lead to a very narrow pulse width and cannot be directly applied in radiation tests of TED, especially the TED with abundant low-frequency components such as fast transient overvoltage and high-altitude electromagnetic pulse. To address this problem, a theoretical radiation model and a design principle of the back-loading method are proposed to compensate for the low-frequency performance. After the optimization of the structure according to the simulated results, a TED testing system with the aperture width of 0.9 m and the length of 1.8 m is built. The rise time of the electric field measured at the center of the aperture is 2.39 ns, the pulse width is 27.65 ns, and the peak field is over 50 kV/m, which can meet the requirements of relative standards. The dimension of the working volume is estimated as 0.4 × 0.5 × 0.5 m3 according to the field distribution.
A dual memristive Wien-bridge chaotic system with variable amplitude and frequency
Authors: Jiang Yanling , Yuan Fang , Li Yuxia
Published: December 2020

In this paper, a first-order generalized memristor and a polynomial memristor are designed to construct a dual memristive Wien-bridge chaotic system. The proposed system possesses rich dynamic characteristics, including alternating between the periodic state and the chaotic state, variable amplitude and frequency, coexisting attractors, and a locally sustained chaotic state. The dynamic behaviors are obtained and investigated by using Lyapunov exponents, bifurcation diagrams, phase portraits, time-domain waveforms, frequency spectra, and so on. The presented chaotic system is implemented by using a digital signal processing platform. Finally, the National Institute of Standards and Technology test is conducted in this paper. Since the system has rich dynamic behaviors, it has great potential value in encryption engineering fields.
Fluid dynamics simulations show that facial masks can suppress the spread of COVID-19 in indoor environments
Authors: Khosronejad Ali , Santoni Christian , Flora Kevin , Zhang Zexia , Kang Seokkoo , Payabvash Seyedmehdi , Sotiropoulos Fotis
Published: December 2020

The coronavirus disease outbreak of 2019 has been causing significant loss of life and unprecedented economic loss throughout the world. Social distancing and face masks are widely recommended around the globe to protect others and prevent the spread of the virus through breathing, coughing, and sneezing. To expand the scientific underpinnings of such recommendations, we carry out high-fidelity computational fluid dynamics simulations of unprecedented resolution and realism to elucidate the underlying physics of saliva particulate transport during human cough with and without facial masks. Our simulations (a) are carried out under both a stagnant ambient flow (indoor) and a mild unidirectional breeze (outdoor), (b) incorporate the effect of human anatomy on the flow, (c) account for both medical and non-medical grade masks, and (d) consider a wide spectrum of particulate sizes, ranging from 10 µm to 300 µm. We show that during indoor coughing some saliva particulates could travel up to 0.48 m, 0.73 m, and 2.62 m for the cases with medical grade, non-medical grade, and without facial masks, respectively. Thus, in indoor environments, either medical or non-medical grade facial masks can successfully limit the spreading of saliva particulates to others. Under outdoor conditions with a unidirectional mild breeze, however, leakage flow through the mask can cause saliva particulates to be entrained into the energetic shear layers around the body and transported very fast at large distances by the turbulent flow, thus limiting the effectiveness of facial masks.
Consumptive coagulopathy of severe yellow fever occurs independently of hepatocellular tropism and massive hepatic injury
Authors: Bailey Adam L. , Kang Liang-I , de Assis Barros D’Elia Zanella Luiz Gonzaga Francisco , Silveira Cássia G. T. , Ho Yeh-Li , Foquet Lander , Bial Greg , McCune Broc T. , Duarte-Neto Amaro Nunes , Thomas Archana , Raué Hans-Peter , Byrnes Kathleen , Kallas Esper G. , Slifka Mark K. , Diamond Michael S.
Published: December 2020

Significance

Fatal cases of yellow fever are preceded by the development of hemorrhagic complications. While yellow fever virus is known to infect hepatocytes, the relationship between hepatocyte infection and the development of hemorrhage is currently undefined. Here, we identified high concentrations of D-dimer in the blood of yellow fever patients, indicative of a process that involves the activation and consumption of clotting factors. We then developed a mouse model in which only transplanted human hepatocytes could be infected at high levels. By examining clotting parameters in this model, we determined that hepatocyte infection alone is insufficient to cause the activation and consumption of coagulation factors observed in severe cases of yellow fever in humans and nonhuman primates.
Perpendicular magnetic anisotropy in half-metallic thin-film Co2CrAl
Authors: Carlile Ryan , Herran Juliana , Poddar Shashi , Montgomery Eric J , Kharel Parashu , Shand Paul M , Lukashev Pavel V
Published: December 2020

Magnetocrystalline anisotropy (MCA) is one of the key parameters investigated in spin-based electronics (spintronics), e.g. for memory applications. Here, we employ first-principles calculations to study MCA in thin film full Heusler alloy Co2CrAl. This material was studied in the past, and has been reported to exhibit half-metallic electronic structure in bulk geometry. In our recent work, we showed that it retains a 100% spin-polarization in thin-film geometry, at CrAl atomic surface termination. Here, we show that the same termination results in a perpendicular magnetic anisotropy, while Co surface termination not only destroys the half-metallicity, but also results in in-plane magnetization orientation. In addition, for films thicker than around 20 nm the contribution from magnetic shape anisotropy may become decisive, resulting in in-plane magnetization orientation. To the best of our knowledge, this is one of the first reports of half-metallic thin-film surfaces with perpendicular magnetic anisotropy. This result may be of interest for potential nano-device applications, and may stimulate a further experimental study of this and similar materials.
Graphene oxide/graphene hybrid film with ultrahigh ammonia sensing performance
Authors: Hue Nguyen The , Wu Qiang , Liu Weihua , Bu Xiangrui , Wu Haiyang , Wang Chang , Li Xin , Wang Xiaoli
Published: December 2020

In this paper, a novel ammonia detection hybrid film is proposed based on a graphene oxide (GO)/graphene stack, which shows excellent sensing characteristics at room temperature. It is attributed to the cooperation of GO layer serving as molecular capture layer while graphene serving as conductive layer. GO layer is obtained on chemical vapor deposited graphene film by a simple drop-casting method. The prepared GO/graphene hybrid film is directly transferred to the target substrate without any additional transfer vehicle to reduce possible contamination. The success of the transfer depends on the mechanical strength of GO layer. The thickness of GO layer can scale down to 55 nm while sustaining the transfer process. The best ammonia gas sensing performance is obtained at about 275 nm GO layer thickness and the ammonia detection limit is calculated to be 1.5 ppb. In conclusion, the ammonia gas sensing performance of GO/graphene hybrid film can be significantly improved through GO layer thickness optimization.