bluuebunny/crossref_metadata_2025 huggingface dataset:
Tongue- and Jaw-Specific Articulatory Changes and Their Acoustic Consequences in Talkers With Dysarthria due to Amyotrophic Lateral Sclerosis: Effects of Loud, Clear, and Slow Speech
Authors: Mefferd Antje S. , Dietrich Mary S.
Published: July 2020

Purpose

This study aimed to determine how tongue and jaw displacement changes impact acoustic vowel contrast in talkers with amyotrophic lateral sclerosis (ALS) and controls.

Method

Ten talkers with ALS and 14 controls participated in this study. Loud, clear, and slow speech cues were used to elicit tongue and jaw kinematic as well as acoustic changes. Speech kinematics was recorded using three-dimensional articulography. Independent tongue and jaw displacements were extracted during the diphthong /ai/ inkite. Acoustic distance between diphthong onset and offset in Formant 1–Formant 2 vowel space indexed acoustic vowel contrast.

Results

In both groups, all three speech modifications elicited increases in jaw displacement (typical < slow < loud < clear). By contrast, only slow speech elicited significantly increased independent tongue displacement in the ALS group (typical = loud = clear < slow), whereas all three speech modifications elicited significantly increased independent tongue displacement in controls (typical < loud < clear = slow). Furthermore, acoustic vowel contrast significantly increased in response to clear and slow speech in the ALS group, whereas all three speech modifications elicited significant increases in acoustic vowel contrast in controls (typical < loud < slow < clear). Finally, only jaw displacements accounted for acoustic vowel contrast gains in the ALS group. In controls, however, independent tongue displacements accounted for increases in vowel acoustic contrast during loud and slow speech, whereas jaw and independent tongue displacements accounted equally for acoustic vowel contrast change during clear speech.

Conclusion

Kinematic findings suggest that slow speech may be better suited to target independent tongue displacements in talkers with ALS than clear and loud speech. However, given that gains in acoustic vowel contrast were comparable for slow and clear speech cues in these talkers, future research is needed to determine potential differential impacts of slow and clear speech on perceptual measures, such as intelligibility. Finally, findings suggest that acoustic vowel contrast gains are predominantly jaw driven in talkers with ALS. Therefore, the acoustic and perceptual consequences of direct instructions of enhanced jaw movements should be compared to cued speech modification, such as clear and slow speech in these talkers.
The Advantages of Retrieval-Based and Spaced Practice: Implications for Word Learning in Clinical and Educational Contexts
Authors: Gordon Katherine R.
Published: July 2020

Purpose

Researchers in the cognitive sciences have identified several key training strategies that support good encoding and retention of target information. These strategies are retrieval-based practice, also known as learning through testing, and spaced practice. The recent resurgence of research on retrieval-based and spaced practice has been extended to investigate the effectiveness of these strategies to support learning in individuals with language disorders. The purpose of the current article is to review key principles of retrieval-based and spaced practice that can be used to support word learning in individuals within clinical and educational contexts.

Conclusion

Current research provides evidence that principles of retrieval-based and spaced practice can enhance word learning for individuals with language disorders. Current research provides guidance for clinicians on how to implement these strategies both within and across sessions to support encoding and retention of target information. Additional research should be conducted to provide a better understanding of how to optimize encoding and retention in clinical and educational contexts. Most notably, research that examines long-term retention after interventions are withdrawn would further our understanding of how these principles can be optimally applied to improve outcomes for individuals with language disorders.
ALMA Deep Field in SSA22
Authors: Umehata Hideki , Smail Ian , Swinbank A. M. , Kohno Kotaro , Tamura Yoichi , Wang Tao , Ao Yiping , Hatsukade Bunyo , Kubo Mariko , Nakanishi Kouchiro , Hayatsu Natsuki N.
Published: July 2020

Deep surveys with the Atacama Large Millimeter Array (ALMA) have uncovered a population of dusty star-forming galaxies which are faint or even undetected at optical to near-infrared wavelengths. Their faintness at short wavelengths makes the detailed characterization of the population challenging. Here we present a spectroscopic redshift identification and a characterization of one of these near-infrared-dark galaxies discovered by an ALMA deep survey. The detection of [C I](1–0) and CO(4–3) emission lines determines the precise redshift of the galaxy, ADF22.A2, to be z = 3.9913 ± 0.0008. On the basis of a multi-wavelength analysis, ADF22.A2 is found to be a massive, star-forming galaxy with a stellar mass of M∗ = 1.1−0.6+1.3 × 1011 M⊙ and SFR = 430−150+230 M⊙ yr−1. The molecular gas mass was derived to be M(H2)[CI] = (5.9 ± 1.5)×1010 M⊙, indicating a gas fraction of ≈35%, and the ratios of L[CI](1−0)/LIR and L[CI](1−0)/LCO(4−3) suggest that the nature of the interstellar medium in ADF22.A2 is in accordance with those of other bright submillimeter galaxies. The properties of ADF22.A2, including the redshift, star-formation rate, stellar mass, and depletion time scale (τdep ≈ 0.1−0.2 Gyr), also suggest that ADF22.A2 has the characteristics expected for the progenitors of quiescent galaxies at z ≳ 3. Our results demonstrate the power of ALMA contiguous mapping and line scan, which help us to obtain an unbiased view of galaxy formation in the early Universe.
Research on the Application of Emotional Design in Cultural Creative Product Design
Authors: Hou Yajing
Published: July 2020

In recent years, cultural creative products as an important branch of cultural creative industries, have been widespread concern and promotion. It is not only a cultural heritage, but also the crystallization of the wisdom of designers, and it is one of the important means of cultural heritage and spread. The creative design is the interpretation of cultural heritage and the refinement of cultural spirit, and it needs to combine the characteristics of the present era and the series of cultural re-design activities carried out by the social aesthetic. The product design needs not only to embody the functionality of the product, but also to the inheritance of cultural spirit, and to pay more attention to people’s sense of identity and belonging to the culture. Based on the three-level theory of emotional design proposed by Professor Donald Arthur Norman, this paper analyzes its specific application in the design of cultural and creative products, in order to establish the emotional design criteria of cultural and creative products centered on user experience. It aims to help consumers establish a sense of design identity and cultural identity for cultural and creative products, and put cultural confidence into practice.
Time Requirement and Feasibility of a Systematic Quality Peer Review of Reporting in Radiology
Authors: Maurer Martin H. , Brönnimann Michael , Schroeder Christophe , Ghadamgahi Ehssan , Streitparth Florian , Heverhagen Johannes T. , Leichtle Alexander , de Bucourt Maximilian , Meyl Tobias Philipp
Published: July 2020

Objective To estimate the human resources required for a retrospective quality review of different percentages of all routine diagnostic procedures in the Department of Radiology at Bern University Hospital, Switzerland.

Materials and Methods Three board-certified radiologists retrospectively evaluated the quality of the radiological reports of a total of 150 examinations (5 different examination types: abdominal CT, chest CT, mammography, conventional X-ray images and abdominal MRI). Each report was assigned a RADPEER score of 1 to 3 (score 1: concur with previous interpretation; score 2: discrepancy in interpretation/not ordinarily expected to be made; score 3: discrepancy in interpretation/should be made most of the time). The time (in seconds, s) required for each review was documented and compared. A sensitivity analysis was conducted to calculate the total workload for reviewing different percentages of the total annual reporting volume of the clinic.

Results Among the total of 450 reviews analyzed, 91.1 % (410/450) were assigned a score of 1 and 8.9 % (40/450) were assigned scores of 2 or 3. The average time (in seconds) required for a peer review was 60.4 s (min. 5 s, max. 245 s). The reviewer with the greatest clinical experience needed significantly less time for reviewing the reports than the two reviewers with less clinical expertise (p < 0.05). Average review times were longer for discrepant ratings with a score of 2 or 3 (p < 0.05). The total time requirement calculated for reviewing all 5 types of examination for one year would be more than 1200 working hours.

Conclusion A retrospective peer review of reports of radiological examinations using the RADPEER system requires considerable human resources. However, to improve quality, it seems feasible to peer review at least a portion of the total yearly reporting volume.

Key Points: 

Citation Format
Retroperitoneal Fibrosis and its Differential Diagnoses: The Role of Radiological Imaging
Authors: Peisen Felix , Thaiss Wolfgang Maximilian , Ekert Kaspar , Horger Marius , Amend Bastian , Bedke Jens , Nikolaou Konstantin , Kaufmann Sascha
Published: July 2020

Background Retroperitoneal fibrosis is a rare disease with an incidence of 0–1/100 000 inhabitants per year and is associated with chronic inflammatory fibrosis of the retroperitoneum and the abdominal aorta. This article sheds light on the role of radiological imaging in retroperitoneal fibrosis, names various differential diagnoses and provides an overview of drug and surgical treatment options.

Methods A literature search for the keywords “retroperitoneal fibrosis” and “Ormond’s disease” was carried out in the PubMed database between January 1, 1995 and December 31, 2019 (n = 1806). Mainly original papers were selected, but also reviews, in English and German language, with a focus on publications in the last 10 years, without excluding older publications that the authors believe are relevant to the topic discussed in the review (n = 40).

Results and Conclusion Ormond’s disease is a rare but important differential diagnosis for nonspecific back and flank pain. Imaging diagnostics using CT or MRI show a retroperitoneal mass, which must be differentiated from lymphoma, sarcoma, multiple myeloma and Erdheim-Chester disease. Patients have an excellent prognosis under adequate therapy. FDG-PET/CT or FDG-PET/MRT should be considered as potential modalities, as hybrid imaging can evaluate both the morphological changes and the inflammation.

Key Points: 

Citation Format
Minimal Stabilization Time for Ultra-short Heart Rate Variability Measurements in Professional Soccer
Authors: Forner-Llacer Francisco , Aranda-Malaves Rodrigo , Aranda Malavés Rafael , Calleja-Gonzalez Julio , Perez-Turpin Jose Antonio , Gonzalez-Rodenas Joaquin
Published: July 2020

The main aims of this study were: 1) to compare 1-minute RMSSD measurements using different stabilization times between them and also with the criterion; and 2) to determine the agreement between every 1-minute RMSSD measurement with the criterion in professional soccer players. Seven hundred eighteen HRV measurements from professional soccer players were taken. HRV was calculated from 5 to 10 minutes (criterion) and from 1-minute windows with different pre-stabilization times. Friedman and post-hoc tests were applied to compare 1-minute and criterion measurements. Effect size was considered to describe magnitude of change. To determine agreement, Spearman’s correlation was applied, and Bland–Altman analysis was also done between each ultra-short HRV time window and the 5-minute HRV criterion period. The 1-minute HRV without any pre-stabilization time was the only one different from all the other 1-minute measurements that included 1 or more minutes of pre-stabilization (p<0.001). One-minute HRV measurements with 1 or more minutes of pre-stabilisation were highly correlated with those for the criterion period. One-minute HRV without pre-stabilization showed the lowest correlation and the highest bias from the criterion. It is concluded that 1-minute HRV measurements with a prior 1-minute or longer pre-stabilization time are valid to measure HRV in professional male soccer players.
DNVF Memorandum Gesundheitskompetenz (Teil 1) – Hintergrund,
Relevanz, Gegenstand und Fragestellungen in der
Versorgungsforschung
Authors: Ernstmann Nicole , Bauer Ullrich , Berens Eva-Maria , Bitzer Eva Maria , Bollweg Torsten Michael , Danner Martin , Dehn-Hindenberg Andrea , Dierks Marie Luise , Farin Erik , Grobosch Sandra , Haarig Frederik , Halbach Sarah , Hollederer Alfons , Icks Andrea , Kowalski Christoph , Kramer Ursula , Neugebauer Edmund , Okan Orkan , Pelikan Jürgen , Pfaff Holger , Sautermeister Jochen , Schaeffer Doris , Schang Laura , Schulte Hilde , Siegel Achim , Sundmacher Leonie , Vogt Dominique , Vollmar Horst Christian , Stock Stephanie
Published: July 2020

Mehr als die Hälfte der deutschen Bevölkerung hat Schwierigkeiten
im Umgang mit Gesundheitsinformationen. Es ist eine wichtige Aufgabe der
Versorgungsforschung zu untersuchen, wie sich die Professionen und
Organisationen des Gesundheitssystems dieser Herausforderung stellen
können. Das DNVF Memorandums Gesundheitskompetenz (Teil 1) nimmt
Begriffsbestimmungen der individuellen und organisationalen Gesundheitskompetenz
vor, präsentiert den nationalen und internationalen Forschungsstand und
stellt ethische Aspekte der versorgungsbezogenen Gesundheitskompetenzforschung
dar. Weiterhin wird die Relevanz der Gesundheitskompetenzforschung in
verschiedenen Lebensphasen, bei unterschiedlichen Personengruppen sowie in
verschiedenen Kontexten der Gesundheits- und Krankenversorgung erarbeitet. Vor
diesem Hintergrund werden zentrale Forschungsgegenstände und
zukünftige Forschungsdesiderata abgeleitet.
Flattening the COVID-19 Curve: The Impact of Contact Restrictions on
the Infection Curve in Germany
Authors: Valentowitsch Johann
Published: July 2020

Although Germany is coping well with the coronavirus crisis, many voices are
currently being raised that fundamentally question the success of the contact
restriction strategy to contain the virus. I show in this study that there is no
justification for such criticism. In fact, contact restrictions have flattened
the infection curve and were possibly decisive for the good German performance
in the crisis.
COVID-19: …Order!
Authors: Wildner Manfred
Published: July 2020

Die schnarrende Stimme John Bercows, Speaker des Britischen Unterhauses, wird noch eine Weile erinnert werden. Seine „Order!“-Rufe während der hitzigen Brexit-Debatten des Jahres 2019 und sein Verweis auf parlamentarische Regeln aus dem Jahr 1604, welcher eine wiederholte Abstimmung über einen unveränderten Brexit-Antrag verhinderte, verschafften ihm allerdings auch etliche Animositäten. Notwendig waren seine beherzten Zwischenrufe in diesen turbulenten Zeiten allemal, der sonst übliche Sitz im Oberhaus im Anschluss an seine Zeit als Sprecher wurde ihm allerdings verwehrt. Dass die Corona-Krise neue Turbulenzen zeitgleich zu den Austrittsverhandlungen hervorbringen würde, kam für das Vereinigte Königreich ebenso überraschend wie für die Europäische Union. Dass in Deutschland diese turbulenten Zeiten bisher vergleichsweise gut bewältigt wurden – bisher ohne erkennbare Einschränkungen einer bestmöglichen gesundheitlichen Versorgung zumindest bei COVID-19-Patienten – ist eine erhebliche Leistung von vielen. Eine der Stimmen in den COVID-19-Turbulenzen, welche in zeitgeschichtlicher Erinnerung bleiben werden, ist die des Generaldirektors der Weltgesundheitsorganisation (WHO) Tedros Adhanom Ghebreyesus von Mitte März 2020: „Man kann ein Feuer nicht blind bekämpfen und wir können dieser Pandemie nicht Einhalt gebieten, wenn wir nicht wissen, wer infiziert ist. Wir haben eine einfache Botschaft für alle Länder: testen, testen, testen. Testen Sie jeden Verdachtsfall. Bei einem positiven Testergebnis isolieren Sie diesen und finden Sie die Kontaktpersonen“ 1. Diese Botschaft verbreitete sich nachfolgend in verkürzter Form als kulturelles Mem „testen, testen, testen“ gleichsam selbst viral über das Internet und andere Kommunikationskanäle. Innerhalb Deutschlands wurde dieser Botschaft jedenfalls entsprochen: Waren in den ersten 10 Kalenderwochen des Jahres 2020 insgesamt 125 000 Abstrichuntersuchungen mittels Reverse-Transkriptase-Polymerase-Kettenreaktion (RT-PCR) vorgenommen worden, wurden bereits einen Monat nach diesem Aufruf wöchentlich etwa 400 000 Testungen durchgeführt. Der Anteil an positiven Befunden sank von etwa 9% um etwa den Faktor 10 auf 1% zwei Monate später 2.
Kostenvergleichsanalyse von flexiblen HNO-Endoskopen
Authors: Becker Sven , Thum Katharina , Philipp Julia , Hagemann Jan , Eckrich Jonas , Ernst Benjamin
Published: July 2020

Hintergrund Die hygienische, richtliniengetreue Wiederaufbereitung von komplexen Instrumenten wie flexiblen HNO-Endoskopen mit und ohne Arbeitskanal stellt Kliniken und Praxen zunehmend vor große Herausforderungen. Ziel der vorliegenden Studie war es daher, die Kosten für ein wiederaufbereitbares Endoskopie-System mit 2 Einweg-Endoskopie-Systemen zu vergleichen und daraus mögliche strategische Überlegungen abzuleiten.

Methodik Hierzu wurde eine Kostenvergleichsanalyse bzw. Kostenminimierungsanalyse des an der Hals-, Nasen-, Ohrenklinik und Poliklinik der Universitätsmedizin Mainz vorgehaltenen Endoskopie-Systems mit 2 Einweg-Endoskopie-Systemen der Firma Ambu und Karl Storz durchgeführt.

Ergebnisse Die Berechnung der Gesamtkosten des wiederaufbereitbaren Endoskopie-Systems ergab einen Gesamtbetrag von 23,03 € pro Untersuchung (11,60 € Investitionskosten + 5,09 € Reparaturkosten + 6,34 € Wiederaufbereitungskosten). Das Einweg-Endoskopie-System der Firma Ambu schlug mit 120,43 € pro Untersuchung (120,00 € Anschaffungskosten + 0,43 € Lagerungskosten) zu Buche. Das Einweg-Endoskopie-System der Firma Karl Storz kostete 223,44 € pro Untersuchung (Investitionskosten für Monitor 3,01 € + 220,00 € Anschaffungskosten + 0,43 € Lagerungskosten).

Diskussion Flexible HNO-Einweg-Endoskope verursachen im Vergleich zu konventionellen, wiederaufbereitbaren Systemen höhere Kosten. Aus medizinischer, aber auch ökonomischer Sicht bieten sie jedoch auch Vorteile.

Schlussfolgerung Ein guter Mix aus wiederaufbereitbaren Endoskopie-Systemen und Einweg-Systemen, z. B. zur Behandlung von Patienten mit Besiedelung durch kritische Erreger, erscheint daher sinnvoll.
Post-Cesarean Peritonitis Caused by Hysterorrhaphy Dehiscence with
Puerperal Acute Abdomen Syndrome
Authors: Pavoković Dino , Cerovac Anis , Ljuca Dženita , Habek Dubravko
Published: July 2020

We present an overview of the case of a patient with early hysterorrhaphy
dehiscence (uteroperitoneal fistula) with endomyometritis and post-cesarean
section peritonitis and puerperal acute abdomen in a 35-year-old puerpera. A
exploratory relaparotomy, necrectomy, and resuture of the dehiscent part of the
hysterotomy were performed with placement of hemostatic sponges on the same
portion of the uterus with good recovery.
The Myth of May Thurner
Authors: Toonder Irwin M.
Published: July 2020

Less invasive contemporary endovenous techniques with improved stents have made treatment of the May Thurner Syndrome(MTS) more accessible and safer. However, clear criteria for the accurate diagnosis remain obscure. All imaging modalities are performed with patients in a supine position were compression of the left Common Iliac Vein is seen in both asymptomatic and symptomatic patients. There is no clear threshold value. There are no validated hemodynamic criteria. This leads to the necessity of additional information such as measurements performed in an upright position as well as greater scrutiny in detecting fibrous wall thickening and spurs as well as identifying the presence of venous collaterals. Moreover, those contemplating treating MTS should not only identify specific symptoms, but also should consider that patient complaints may be related to a more complex presentation of pelvic congestion.
Specifications Grading: What It Is, and Lessons Learned
Authors: Leslie Paula , Lundblom Erin
Published: July 2020

Traditional point-based grading is failing students entering a competency-based workforce: Employers require concrete skills and knowledge, not “high” grades. In the specifications approach, learning outcomes are explicitly linked to the grading system. The basic components of the approach include clear alignment of learning outcomes to certification standards, bundled sequences of assessments tied to basic and advanced competency/learning outcomes, pass/fail grading with no partial credit, opportunities to revise unacceptable work, and detailed expectations of performance on assessments. This article describes the specifications approach and provides examples highlighting how to (1) align course learning objectives with a grading system, (2) implement a pass/fail approach even for complex assessment, (3) define specifications, (4) create and sequence bundles of assessments, and (5) provide instructor support through feedback and tokens.
Is There an Additional Value in Detecting Anticardiolipin and Anti-β2 glycoprotein I IgA Antibodies in the Antiphospholipid Syndrome?
Authors: Chayoua Walid , Yin Dong-mei , Kelchtermans Hilde , Moore Gary W. , Gris Jean-Christophe , Musiał Jacek , Zuily Stéphane , ten Cate Hugo , de Laat Bas , Devreese Katrien M. J.
Published: July 2020

Background Anticardiolipin (aCL) and anti-β2 glycoprotein I (aβ2GPI) immunoglobulin A (IgA) antiphospholipid antibodies (aPL) have shown to associate with thrombosis and pregnancy morbidity. However, inclusion of IgA aPL in the classification criteria of the antiphospholipid syndrome (APS) has been debated. We investigated the value of aCL and aβ2GPI IgA aPL in the detection of thrombosis and pregnancy morbidity in addition to the current aPL panel for APS.

Methods We included 1,068 patients from eight European medical centers: 259 thrombotic APS patients, 122 obstetric APS patients, 204 non-APS thrombosis patients, 33 non-APS obstetric patients, 60 APS patients with unspecified clinical manifestations, 196 patients with autoimmune diseases, and 194 controls. aCL and aβ2GPI IgG/M/A were detected with four commercial assays and lupus anticoagulant was determined by the local center.

Results Positivity for IgA aPL was found in 17 to 26% of the patients with clinical manifestations of APS and in 6 to 13% of the control population. Both aCL and aβ2GPI IgA were significantly associated with thrombosis and pregnancy morbidity. Isolated IgA positivity was rare in patients with clinical manifestations of APS (0.3–5%) and not associated with thrombosis and/or pregnancy morbidity. Addition of IgA to the current criterion panel did not increase odds ratios for thrombosis nor pregnancy morbidity.

Conclusion aCL and aβ2GPI IgA are associated with clinical manifestations of APS. However, isolated IgA positivity was rare and not associated with thrombosis or pregnancy morbidity. These data do not support testing for aCL and aβ2GPI IgA subsequent to conventional aPL assays in identifying patients with thrombosis or pregnancy morbidity.
Uniform regularity for a two-phase model with magneto field and a related system
Authors: Fan Jishan , Nakamura Gen , Tang Tong
Published: July 2020

This paper proves some uniform regularity estimates for a two-phase model with a magnetic field and a related system in Td.
Low- and high-frequency nature of oblique filamentation modes. I. Linear theory
Authors: Ghizzo A. , Del Sarto D. , Sarrat M.
Published: July 2020

The solution of the linear dispersion relation of electromagnetic oblique instabilities, for two counterstreaming electron beams, is investigated by using an extended fluid approach that includes the full dynamics of the pressure tensor. Numerical solutions of the simplified polynomial formulation so obtained are analyzed and compared to full kinetic solutions. They correspond to two classes of eigenmodes: low- and high-frequency oblique modes of resonant character. Coexistence of several oblique modes in neighboring regions of the wave vector plane, having close growth-rates, leads to the possibility of a transition starting from a low wave number mode to an oblique mode of high values in wave numbers. For such counterstreaming plasmas, the oblique instability may strengthen and amplify the filamentation process of the distribution function in velocity space, a property of the Vlasov equation. In addition to its simplicity, useful for solving the dispersion relation in the linear regime and for identifying kinetic solutions difficult to calculate otherwise, this extended fluid model is helpful in gaining insight into the fundamental properties of Vlasov theory, which are possibly relevant to kinetic heating processes.
Limiting output voltage of isentropic energy-emissive harvesters
Authors: Fernández J. J.
Published: July 2020

In emissive-energy harvesters, electrons from a hot contact are injected into a colder emitter at the high energy εn and then are extracted from it to another hot contact at the lower energy εp. In this work, we prove that the open-circuit voltage of emissive-energy harvesters can be deduced assuming isentropic electron transport conditions between the cell hot contacts and the emitter. We also show that in real emissive-energy harvesters, where the electronic transport is irreversible, the open-circuit voltage is always more negative than the one obtained assuming reversible conditions. The equations introduced in this work are used to obtain the working properties of energy-emissive harvesters using a model that includes a particle balance. A general conclusion is found in this work: the open-circuit voltages of energy-emissive harvesters calculated in previous works are never reached by real ones.
Substrate effect on the photoluminescence of chemical vapor deposition transferred monolayer WSe2
Authors: Liu Dongqi , Yan Xiao-Qing , Guo Hao-Wei , Liu Zhi-Bo , Zhou Wen-Yuan , Tian Jian-Guo
Published: July 2020

The substrate effect is an important issue in the properties of two-dimensional transition metal dichalcogenides (2D TMDs). Quantitatively determining the dependence of the photoluminescence (PL) emission properties and the excitonic behavior of single-layer 2D materials in a specific dielectric environment would provide helpful guidance for the rational design of substrates for high performance 2D TMD PL emission devices. Here, using a WSe2 monolayer on different substrates as a model system, it is demonstrated that the PL emission intensities can drastically change depending on the substrate effect. From the analysis of the excitonic behavior, the results reveal that the spectral weight between the neutral and charged excitons in the PL spectra is significantly modified by the substrate types, and the weight factor is dependent on the laser excitation density. The charged exciton binding energy is obviously negatively related to the substrate dielectric constant. Furthermore, the change trends of the binding energy of the monolayer WSe2 on different substrates are basically the same for the increase of the excitation density. These results suggest that the choice of the substrate plays a significant role in the modulation of the PL properties and exciton states of atomically thin WSe2; hence, substrate engineering should be carefully considered in the design of future 2D devices.
Comparison of the performance of a high voltage generator insulated by gas or liquid dielectric
Authors: Antonini P. , Borsato E. , Carugno G. , Dal Corso F. , Facco A. , Fanin C. , Gallo C. S. , Galatá A. , Gobbo R. , La Torre L. , Montecassiano F. , Pegoraro M. , Poggi M. , Zotto P.
Published: July 2020

A module of a wireless high voltage generator was tested immersed in both gaseous and liquid environments providing electrical insulation. The overall performance of the module as well as a detailed performance of the key components are reported, and a comparison between the results in gas and liquid is given. The tests performed on the liquid dielectric show that it is a valid alternative to high pressure gas electrical insulation.
Unraveling the abnormal dependence of phase stability on valence electron concentration in Ni–Mn-based metamagnetic shape memory alloys
Authors: Yan Hai-Le , Liu Hao-Xuan , Zhao Ying , Jia Nan , Bai Jing , Yang Bo , Li Zongbin , Zhang Yudong , Esling Claude , Zhao Xiang , Zuo Liang
Published: July 2020

Valence electron concentration (e/a) dependence of phase transition temperature TM, i.e., a higher e/a leading to an elevated TM, is a well-accepted criterion for the Ni–Mn-based alloys. However, this tendency is not always obeyed by certain alloy systems, such as the Ni2Mn(Ga, Z) alloys (Z = Si, Ge, and Sn). The origin of this abnormal behavior remains uncovered. In this work, by first-principles calculations, the origin of the abnormal e/a dependence of phase stability in the Ni2MnGa1−xSix (x = 0–1) alloys is elucidated through examining the electronic structure, phonon, and magnetism. We find that the abnormal e/a dependence of phase stability intrinsically originated from the chemical composition change. The composition variation brings about a reduction of the minority-spin electronic states near the Fermi energy and the weakness of the Fermi surface nesting. Moreover, the substitution of Si for Ga leads to a decreased magnetization of austenite and an increased magnetization of martensite, which also makes a non-negligible contribution to the abnormal phase stability. The conclusions drawn for the Ni2MnGa1−xSix alloys can be well extended to understand the structural transition in other abnormal alloying systems, such as the Ni2MnGa1−xZx alloys (Z = Ge and Sn). This work clarifies the origin of the abnormal dependence of phase stability on e/a in the Ni–Mn-based alloys and provides solid knowledge for the design of advanced magnetic shape memory alloys.
Elastic instability in graphite single crystal under dynamic triaxial compression: Effect of strain-rate on the resulting microstructure
Authors: Lafourcade Paul , Denoual Christophe , Maillet Jean-Bernard
Published: July 2020

We focus on the behavior of graphite under triaxial loading at a constant strain-rate using large scale molecular dynamics simulations. Buckling patterns (chevrons) in graphite nucleate from an elastic instability strongly related to the material anisotropy and subsequently grow until the first diamond nuclei appear. We show that the phase transition completely inhibits the growth of chevrons in buckled graphite, the diamond grain size being determined by the size of chevrons at the onset of nucleation. Cubic-diamond clusters nucleate within chevrons of buckled graphite and grow until the parent phase is entirely transformed. This phenomenon leads to nano-structured diamond polycrystals, with orientations of interfaces given by those of the buckled material right before the nucleation process. The buckled graphite microstructure is shown to strongly influence the final microstructure/size of nano-diamonds.
Spectral narrowing of parametrically pumped thermomechanical noise
Authors: Miller James M. L. , Shin Dongsuk D. , Kwon Hyun-Keun , Shaw Steven W. , Kenny Thomas W.
Published: July 2020

We derive the displacement noise spectrum of a parametrically pumped resonator below the onset for self-excited oscillations. We extend the fluctuation-dissipation response of a thermomechanical-noise-driven resonator to the case of degenerate parametric pumping as a function of pump magnitude and frequency while properly accounting for the quadrature-dependence of the parametric thermal noise squeezing. We use measurements with a microelectromechanical cantilever to corroborate our model.
Gyrokinetic studies of fast ion precession driven drift instability in reversed shear plasmas
Authors: Kang B. J. , Kim Y. J. , Angioni C. , Hahm T. S.
Published: July 2020

A new electron drift instability driven by resonance with precession reversed fast trapped ions in reversed magnetic shear tokamak plasmas is identified from gyrokinetic simulations. Results from the initial value GKW code and eigenmode analysis in the ballooning space are in broad agreement with predictions from the local analytic theory [B. J. Kang and T. S. Hahm, Phys. Plasmas 26, 042501 (2019)].
Ab initio study of band gap properties in metastable BC8/ST12 SixGe1−x alloys
Authors: Wagner J. , Núñez-Valdez M.
Published: July 2020

The cubic Ia3¯ (BC8) and tetragonal P43212 (ST12) high pressure modifications of Si and Ge are attractive candidates for application in optoelectronic, thermoelectric, or plasmonic devices. SixGe1−x alloys in BC8/ST12 modifications could help overcome the indirect and narrow bandgaps of the pure phases and enable tailoring for specific use-cases. Such alloys have experimentally been found to be stable at ambient conditions after release from high pressure synthesis; however, their fundamental properties are not known. In this work, we employ ab initio calculations based on density functional theory (DFT) to investigate the electronic properties of these compounds as a function of composition x. We obtain the effective band structures of intermediate alloys by constructing special quasi-random structures (SQSs) and unfolding their band structure to the corresponding primitive cell. Furthermore, we show that the indirect bandgap of the ST12 Ge end-member can be tuned to become direct at xSi≈0.16. Finally, our investigations also demonstrate that the BC8 modification, on the other hand, is insensitive to compositional changes and is a narrow direct bandgap semiconductor only for the case of pure Si.
A broadband wavelet implementation for rapid ultrasound pulse-echo time-of-flight measurements
Authors: Sturtevant Blake T. , Velisavljevic Nenad , Sinha Dipen N. , Kono Yoshio , Pantea Cristian
Published: July 2020

A broadband wavelet approach to ultrasonic pulse-echo time-of-flight measurements is described. The broadband approach significantly reduces the time required for frequency-dependent pulse-echo measurements, enabling studies of dynamic systems ranging from biological systems to solid-state phase transitions. The described broadband approach is demonstrated in parallel with the more traditional frequency stepping approach to perform ultrasound time-of-flight measurements inside a large volume Paris–Edinburgh press in situ at a synchrotron source. The broadband wavelet data acquisition process was found to be 1–2 orders of magnitude faster than the stepped-frequency approach, with no compromise on data quality or determined results.
Size and shape effects on the measured peak temperatures of nanoscale hotspots
Authors: Pickel Andrea D. , Dames Chris
Published: July 2020

As device length scales trend downward, small feature sizes and steep temperature gradients require thermometers with increasingly fine spatial resolution in order to capture the true peak temperature. Here, we develop analytical expressions for the true and measured temperature rises as a function of thermometer size for Gaussian, disk-shaped, and rectangular surface heat sources. We find that even a thermometer the same size as the hotspot can underestimate the true peak temperature rise by more than 15%, and this error frequently exceeds 75% and can approach 90% for certain geometries when the thermometer is ten times larger than the measured hotspot. We show that a thermometer with resolution approximately two times smaller than the hotspot size is required to measure the peak temperature rise with less than 5% error for several common hotspot geometries. We also experimentally demonstrate that a 50 × 50 × 50 nm3 individual upconverting NaYF4:Yb3+,Er3+ nanoparticle thermometer captures the peak temperature rise due to laser heating more accurately than conventional diffraction limited optical techniques that our modeling results show would underestimate this value. In contrast to apparent self-heating effects that spuriously increase the nanoparticle thermometry signal at high excitation intensities, we measure true laser heating, as confirmed by comparing measurements on glass and diamond substrates.
Intensity dependent deflection spectroscopy for the characterization of absorption mechanisms in semiconductors
Authors: Dickmann Walter , Götze Tom , Bieler Mark , Kroker Stefanie
Published: July 2020

We report on a simple method for the characterization of optical absorption in semiconductors at photon energies below the bandgap energy. Therefore, we perform spatially resolved and intensity dependent deflection spectroscopy to measure the local optical absorption. To separate the absorption mechanisms, we take advantage of different intensity scaling of these mechanisms and extract the material parameters by fitting intensity dependent absorption to a physical model. This model takes into account relevant optical absorption processes like linear absorption from defect states, two-photon absorption, and the Franz–Keldysh effect. The method is exemplarily carried out for GaAs, Si, and CdTe. The literature values of the two-photon absorption coefficient are reproduced and the strength of the Franz–Keldysh effect in CdTe is determined for the first time as CFK=[8.7,…,16.9]×1013m−1s−1/2.
Analytic gradients for spin multiplets in natural orbital functional theory
Authors: Mitxelena Ion , Piris Mario
Published: July 2020

Analytic energy gradients with respect to nuclear motion are derived for non-singlet compounds in the natural orbital functional theory. We exploit the formulation for multiplets in order to obtain a simple formula valid for any many-electron system in its ground mixed state with a total spin S and all possible spin projection Sz values. We demonstrate that the analytic gradients can be obtained without resorting to linear response theory or involving iterative procedures. A single evaluation is required, so integral derivatives can be computed on-the-fly along the calculation, thus improving the effectiveness of screening by the Schwarz inequality. The results for small- and medium-sized molecules with many spin multiplicities are shown. Our results are compared with the experimental data and accurate theoretical equilibrium geometries.
Experimental observation of ferroelectricity in ferrimagnet MnCr2S4
Authors: Wang J. X. , Lin L. , Zhang C. , Guo H. F. , Liu J.-M.
Published: July 2020

Ferrimagnetic spinel compounds AB2X4 (A and B are the magnetic transition elements) are considered to be promising candidates for multiferroics with large magnetization and polarization. In this work, we synthesize polycrystalline spinel MnCr2S4 and characterize the magnetic and ferroelectric properties. Two well-defined ferroelectric phase transitions are demonstrated. The first one occurs at the Cr3+ ferromagnetic phase transition temperature of TC = 65 K, and the other takes place at the Yafet–Kittel (YK) magnetic phase transition temperature of TYK ≈ 5 K. It is suggested that ferroelectricity in the YK phase is driven by the noncollinear triangular YK spin orders and can be greatly tuned by an external magnetic field. Between TYK and TC ranges, another opposite electric polarization sublattice appears, which is enhanced by the external magnetic field just near TC, revealing that this opposite electric polarization is likely related to magnetostriction and the magnetic field can enhance the lattice distortions near TC. Thus, this work paves the way for exploiting ferrimagnetic multiferroicity although more studies are needed to clarify the ferroelectricity mechanism in the Cr3+ ferromagnetic phase.
Analytical approach and numerical simulation of hydrodynamic forces in immersion optics
Authors: Hänel Erik , Ziegler Fabian
Published: July 2020

Immersion microscopy optics may include liquid droplets (e.g., water) to control the light pathway and the numerical aperture of an optical system. Changing the distances between the optical system and an object slide for image focusing also changes the shape (especially the diameter) of the droplet and the surface energy, thus leading to forces acting on both optics and object slides. We examine these effects analytically and derive a numerical model using numerical integration of a recursive integral to predict the force resulting from a liquid droplet changing its shape in the system. Our solutions show that an alteration of the distance leads to a time-dependency of the droplet surface, which is reflected in the corresponding surface and meniscus energies. With this, we can calculate the hydrostatic force that pulls both optical surfaces closer to each other and simulate the time-dependent equilibration of the system.
Excitonic coupling effect on the circular dichroism spectrum of sodium-pumping rhodopsin KR2
Authors: Fujimoto Kazuhiro J. , Inoue Keiichi
Published: July 2020

We investigate the role of excitonic coupling between retinal chromophores of Krokinobacter eikastus rhodopsin 2 (KR2) in the circular dichroism (CD) spectrum using an exciton model combined with the transition density fragment interaction (TDFI) method. Although the multimer formation of retinal protein commonly induces biphasic negative and positive CD bands, the KR2 pentamer shows only a single positive CD band. The TDFI calculation reveals the dominant contribution of the Coulomb interaction and negligible contributions of exchange and charge-transfer interactions to the excitonic coupling energy. The exciton model with TDFI successfully reproduces the main features of the experimental absorption and CD spectra of KR2, which allow us to investigate the mechanism of the CD spectral shape observed in the KR2 pentamer. The results clearly show that the red shift of the CD band is attributed to the excitonic coupling between retinal chromophores. Further analysis reveals that the weak excitonic coupling plays a crucial role in the shape of the CD spectrum. The present approach provides a basis for understanding the origin of the KR2 CD spectrum and is useful for analyzing the mechanism of chromophore–chromophore interactions in biological systems.
Hot electron and thermal effects in plasmonic photocatalysis
Authors: Mascaretti Luca , Naldoni Alberto
Published: July 2020

Surface plasmons have shown increasingly widespread applications in the last decade, especially in the field of solar energy conversion, recently leading to the use of metal nanoparticles as plasmonic photocatalysts. The latter offers great potential in overcoming traditional catalysts by providing localized heating and unconventional reaction pathways leading to improved product selectivity. A complete understanding of the underlying mechanisms remains, however, elusive due to the close resemblance between thermal and non-thermal effects, both leading to enhanced reaction rates. In this tutorial, we will introduce the basic physics of surface plasmons and the interaction mechanisms with surrounding molecules. We will then discuss the main strategies to evaluate photothermal effects and the main signatures of hot electron-driven processes. These aspects will be covered in specific examples of plasmonic photocatalysis for energy-relevant chemical reactions in the case of colloidal suspensions and at the solid/gas interphase in solid pellets, which involve different thermal constraints and thus different experimental strategies to reveal the effects of localized heating and hot electrons.
Thermal radiation dominated heat transfer in nanomechanical silicon nitride drum resonators
Authors: Piller Markus , Sadeghi Pedram , West Robert G. , Luhmann Niklas , Martini Paolo , Hansen Ole , Schmid Silvan
Published: July 2020

Nanomechanical silicon nitride (SiN) drum resonators are currently employed in various fields of applications that arise from their unprecedented frequency response to physical quantities. In the present study, we investigate the thermal transport in nanomechanical SiN drum resonators by analytical modeling, computational simulations, and experiments for a better understanding of the underlying heat transfer mechanism causing the thermal frequency response. Our analysis shows that radiative heat loss is a non-negligible heat transfer mechanism in nanomechanical SiN resonators, limiting their thermal responsivity and response time. This finding is important for optimal resonator designs for thermal sensing applications as well as cavity optomechanics.
How to “measure” a structural relaxation time that is too long to be measured?
Authors: Berthier L. , Ediger M. D.
Published: July 2020

It has recently become possible to prepare ultrastable glassy materials characterized by structural relaxation times, which vastly exceed the duration of any feasible experiment. Similarly, new algorithms have led to the production of ultrastable computer glasses. Is it possible to obtain a reliable estimate of a structural relaxation time that is too long to be measured? We review, organize, and critically discuss various methods to estimate very long relaxation times. We also perform computer simulations of three dimensional ultrastable hard spheres glasses to test and quantitatively compare some of these methods for a single model system. The various estimation methods disagree significantly, and non-linear and non-equilibrium methods lead to a strong underestimate of the actual relaxation time. It is not yet clear how to accurately estimate extremely long relaxation times.
Effect of periodic perturbations on the turbulence statistics in a backward-facing step flow
Authors: Li Zhuoyue , Zhang Di , Liu Yakun , Wu Chuijie , Gao Nan
Published: July 2020

Turbulence budget for natural and periodically perturbed backward-facing step flows was studied using particle image velocimetry data, aiming to provide more evidence for the mechanisms of the turbulence production under perturbation. The flow has a Reynolds number of 9630 based on the step height. A synthetic jet actuator deployed at the step corner was used to perturb the flow with a wide range of parameters including different frequencies and amplitudes. The results show that the sizes of the turbulence production terms are enhanced with efficiency when flow is perturbed at a frequency near the shear layer mode frequency. The enhancement is associated with vortical structures produced by the perturbation. The length scale of the structures is similar to the step height. In contrast, the low-frequency perturbation (with a frequency which is 25% of the shear layer mode frequency) has less impact on the turbulence production despite the large amplitude vertical flapping motion of the whole shear layer and large increases in the streamwise Reynolds normal stress occur.