bluuebunny/crossref_metadata_2025 huggingface dataset:
A low-complexity orthogonal time frequency space modulation method for underwater acoustic communication
Authors: ZHANG Yang , ZHANG Qunfei , WANG Yingjie , HE Chengbing , SHI Wentao
Published: December 2021

Compared with the orthogonal frequency division multiplexing (OFDM) modulation, the orthogonal time frequency space(OTFS) modulation has a lower peak-to-average power ratio. It can effectively resist the time selective fading caused by the Doppler effect and has significant performance advantages over doubly dispersive channels. However, the conventional OTFS linear minimum mean square error (LMMSE) method has a high complexity and is not easy to process in real time. In order to solve this problem, we propose a low-complexity equalization algorithm with infinite norm constraints based on the optimal coordinate reduction. The equalization algorithm not only obtains the optimal solution through a certain number of iterations and avoids direct matrix inversion but also equalizes infinite norm constraints to improve the symbol detection performance gains. At the same time, the OTFS delay-Doppler channel matrix we utilize is sparse and the two-norm squares of each column vector equally reduces the complexity of optimal coordinate descent. Finally, the simulation in the underwater acoustic communication scenario we designed verify the effectiveness of the proposed equalization algorithm. The simulation results show that the performance of the proposed equalization algorithm is close to that of the LMMSE method, while its low complexity is ensured.
Analysis of comprehensive sensitivity evaluation of aircraft system based on FTA-AHP
Authors: FENG Yunwen , SONG Zhicen , LU Cheng , LIU Xiaofei
Published: December 2021

Aiming at the lack of unified evaluation index for the sensitivity analysis of fault tree of the system, the Analytic Hierarchy Process(AHP) is introduced into Fault Tree Analysis(FTA), and an FTA-AHP method is proposed to generate the comprehensive sensitivity evaluation index of the system. Firstly, the reliability analysis model of the system fault tree is established, and three indexes including probabilistic sensitivity, relative sensitivity and structural sensitivity, are calculated by using the traditional sensitivity analysis method. Then, combined with the analytic hierarchy process, the weight coefficients were determined according to the sensitivity analysis results above and the type of the minimum cut set, and the comprehensive sensitivity evaluation and analysis of the system fault tree were carried out. Finally, the case verification shows that compared with the traditional method, the comprehensive sensitivity ranking results have less repeatability, and the factors are considered comprehensively, which is convenient for decision makers to make judgment. The synthetic sensitivity evaluation model developed provides support for system reliability analysis.
Investigation on effects of time-frequency characteristics of ship airwake on helicopter flight characteristics
Authors: DENG Jinghui
Published: December 2021

A conventional helicopter flight dynamics model, which can be coupled with ship airwake date, is developed in this study. In the method, the ship airwake data is obtained by the high-accuracy DES model, and a strategy which can transmit CFD data to the flight dynamics model is established based on the "one-way" coupling idea. Then, the SFS2 ship model and UH-60A helicopter are chosen as a combination to investigate the influences of the spatial and temporal characteristics of ship airwake from the aspects of control margins and unsteady level. The time-averaged simulation results show that for the counterclockwise-rotor helicopter, although pilot could have more collective pitch margin under crosswind condition compared to the headwind condition, he might possess much less pedal margin due to the sidewash in the airflow. The unsteady results indicate that the unsteady loading level of the helicopter would increase significantly under the crosswind condition compared to the headwind condition due to the increase of turbulent density in the airwake. Furthermore, for the conventional helicopter, the disturbances on the forces and moments which along the rotor hub (i.e., thrust and yaw moment) are the critical factors that increasing the pilot workload during the landing procedure.
Neurodynamik – Diagnostik und Behandlung bei zervikaler Radikulopathie
Authors: Hirschmann Eike , Albasini Alfio
Published: December 2021

Die Nervenwurzelkompression, die oft mit einer zervikalen Radikulopathie einhergeht, kann auch die Dynamik des Nervensystems beeinflussen. Es gibt verschiedene Techniken, die bei der Diagnose und Therapie einer dysfunktionalen Neurodynamik sinnvoll sind. Doch welcher Test ist der geeignetste? Für diese Entscheidung ist unter anderem sinnvoll, die Irritierbarkeit des Systems in den Clinical-Reasoning-Prozess einzubeziehen.
Konservative Rehabilitation nach Fraktur im Bereich der Halswirbelsäule – ein Fallbericht
Authors: Danler Andreas
Published: December 2021

Nackenschmerz ist einer der häufigsten Gründe, warum Patient(inn)en Physiotherapie in Anspruch nehmen. Liegt eine traumatische Fraktur im Bereich der Halswirbelsäule den Schmerzen zugrunde, kommt es häufig zu einer operativen Versorgung. Dieses Fallbeispiel beschreibt den Rehabilitationsprozess eines jungen Mannes nach einer erlittenen Fraktur im Bereich der Halswirbelsäule, die konservativ versorgt wurde. Im Mittelpunkt der Physiotherapie standen vertrauensbildende Maßnahmen, computergestützte Untersuchungsmethoden der Beweglichkeit, manualtherapeutische Interventionen und eine graduierte Trainingstherapie. Darüber hinaus wurde der Patient in Bezug auf den Rehabilitationsprozess interviewt.
Der Effekt von Action Observation Therapy auf die Extension nach einer vorderen Kreuzbandplastik: eine randomisierte kontrollierte Pilotstudie
Authors: Doutressoulles Benoit , Richter Michael
Published: December 2021

Eine bekannte Komplikation nach einer Plastik des vorderen Kreuzbandes (VKB) ist das Extensionsdefizit (ED). Ziel dieser Studie war, zu erforschen, ob eine zusätzlich zu den klassischen Streckübungen eingesetzte einmalige Anwendung der „Action Observation Therapy“ (AOT) die Extension des Kniegelenks nach einer VKB-Plastik deutlicher verbessert als eine Therapiesitzung ohne AOT.

13 Proband(inn)en mit ED nach einer VKB-Plastik wurden in eine AOT-Gruppe (n = 8) und eine Kontrollgruppe (n = 5) randomisiert. Jede Gruppe erhielt eine Therapiesitzung. Die Therapie bestand aus dem Betrachten eines Videos, gefolgt von aktiven Extensionsübungen, wobei das Video der AOT-Gruppe Extensionsübungen und das der Kontrollgruppe Landschaftsaufnahmen zeigte. Primäres Outcome war das Bewegungsausmaß der aktiven Extension, als sekundäre Outcomes wurden das Bewegungsausmaß der passiven Extension und die Heel-Height Difference (HHD) gemessen. Die Messungen erfolgten direkt vor und nach der Behandlung.

Die aktive Extension verbesserte sich sowohl in der AOT-Gruppe (von ∅ –2,0° (± 6,3) auf ∅ 0,8° (± 3,9), p = 0,036) als auch in der Kontrollgruppe (von ∅ –8,2° (± 5,5) auf ∅ –5,6° (± 4,7), p = 0,049). Die aktive Extension war in der AOT-Gruppe nach der Intervention signifikant besser als in der Kontrollgruppe (p = 0,023). Für die passive Extension und die HHD gab es keine signifikanten Unterschiede zwischen beiden Gruppen.

Bei Patient(inn)en nach einer VKB-Plastik zeigte sich in der Gruppe mit AOT eine bessere aktive Knieextension als in der Kontrollgruppe ohne AOT. Weitere Arbeiten mit einer größeren Stichprobe und einer längeren Verlaufskontrolle sind notwendig, um diese Ergebnisse zu bestätigen.
Telemonitoring with Electronic Devices in Patients with a Single Ventricle Anatomy
Authors: Zartner Peter A. , Mini Nathalie , Momcilovic Diana , Schneider Martin B. , Dittrich Sven
Published: December 2021

Background A growing number of patients with a single ventricle anatomy, who had a Fontan palliation as a child, are now reaching adulthood. Many need an epimyocardial pacemaker system with an optional telemonitoring (TM) unit, which evaluates the collected data and sends it via Internet to the patient's physician. There are no data on the reliability and clinical relevance of these systems in this patient group.

Methods We analyzed data in 48 consecutive patients (mean age 18 years, standard deviation 9 years) with a Fontan or Fontan-like palliation who received a cardiac implantable electronic device with a TM unit from Biotronik (Home Monitoring) or Medtronic (CareLink) between 2005 and 2020 with regard to the reliability and clinical relevance of the downloaded data.

Results The observation period was from 4 months to 14 years (mean 7 years, standard deviation 3.9 years). A total of 2.9 event messages (EMs)/patient/month and 1.3 intracardiac electrogram recordings/patient/month were received. Two patients died during follow-up. The combination of regularly arriving statistical data and 313 clinically relevant EMs led to the modification of antiarrhythmic or diuretic medication, hospitalization with cardioversion or ablation, and cortisone therapy to avoid exit block in 21 (44%) patients.

Conclusion TM is an instrument to receive functional and physiologic parameters of our Fontan patients. It provides the ability to respond early for signs of system failure, or arrhythmia, even if the patient is not experiencing any problems. It is a useful tool to manage this difficult patient population without frequent hospital visits.
Preoperative Classification System Used to Determine Release Performed during Endoscopic Brow Lift
Authors: Freeman M. Sean
Published: December 2021

The techniques presented in article will allow the facial plastic specialist to use the anatomy of each individual patient as a guide for the surgical release of the brow performed during endoscopic brow lift. The author presents his 15 years of experience in which he developed this approach. Five different surgical releases of the brow will be demonstrated and discussed in terms of which patients would best benefit from which release. Adopting this approach has made the predictability of the authors brow lift results much better and therefore improved patient satisfaction. This concept has not been described in the literature and the author firmly believes using a preoperative anatomical approach is a better way to approach endoscopic brow lift surgery.
Racial and Ethnic Disparities in Cesarean Morbidity
Authors: Kern-Goldberger Adina R. , Booker Whitney , Friedman Alexander , Gyamfi-Bannerman Cynthia
Published: December 2021

Objective Maternal race and ethnicity have been identified as significant independent predictors of obstetric morbidity and mortality in the United States. An appreciation of the clinical contexts in which maternal racial and ethnic disparities are most pronounced can better target efforts to alleviate these disparities and improve outcomes. It remains unknown whether cesarean delivery precipitates these divergent outcomes. This study assessed the association between maternal race and ethnicity and cesarean complications.

Study Design We conducted a retrospective cohort study from a multicenter observational cohort of women undergoing cesarean delivery. Nulliparous women with non-anomalous singleton gestations who underwent primary cesarean section were included. Race/ethnicity was categorized as non-Hispanic White, non-Hispanic Black, Hispanic, Asian, Native American, or unknown. The primary outcome was a composite of maternal cesarean complications including hysterectomy, uterine atony, blood transfusion, surgical injury, arterial ligation, infection, wound complication, and ileus. A composite of neonatal morbidity was evaluated as a secondary outcome. We created a multivariable logistic regression model adjusting for selected demographic and obstetric variables that may influence the likelihood of the primary outcome.

Results A total of 14,570 women in the parent trial met inclusion criteria with an 18.8% incidence of the primary outcome (2,742 women). After adjusting for potential confounding variables, maternal surgical morbidity was found to be significantly higher for non-Hispanic Black (adjusted odds ratios [aORs] 1.96, 95% confidence intervals [CIs] 1.63–2.35) and Hispanic (aOR 1.66, 95% CI 1.37–2.01) women as compared with non-Hispanic white women. Neonatal morbidity was similarly found to be significantly associated with the Black race and Hispanic ethnicity.

Conclusion In this cohort, the odds of cesarean-related maternal and neonatal morbidity were significantly higher for non-Hispanic Black and Hispanic women. These findings suggest race as a distinct risk factor for cesarean complications, and efforts to alleviate disparities should highlight cesarean section as an opportunity for improvement in outcomes.

Key Points
Esophageal Interventions in Infants Born with Esophageal Atresia: A Comprehensive Analysis of a National Database
Authors: König Tatjana T. , Gianicolo Emilio , Frankenbach Luisa , Wittenmeier Eva , Muensterer Oliver J.
Published: December 2021

Introduction Esophageal atresia (EA) is a rare malformation that often requires a series of procedures, including surgical primary anastomosis, staged repair, and endoscopic procedures. Actual numbers and trends in interventions and variety in treatment strategies remain unclear.

Materials and Methods Data from the German federal bureau of statistics containing all EA-related inpatient procedures encoded from 2005 until 2018 were analyzed for children during the first year of life. The sum of esophageal anastomoses and replacements was used to calculate an estimate of incidence of EA.

Results Over 14 years, 12,627,888 inpatient cases were recorded in infants in Germany. The mean incidence of EA was 1 per 4,217 live births. On average, 163.3 (95% confidence interval [CI]: 150.8–176.1) esophageal anastomoses, 11.2 (95% CI: 8.7–13.7) esophageal lengthening procedures, and 6.7 (95% CI: 5.42–8.00) esophageal replacements were recorded annually. Overall, 187.8 (95% CI: 147.1–200.4) endoluminal treatments (ballon dilatation, bougienage, stent placement, or injection) were performed per 100 anastomoses. Over the years, bougienage was increasingly replaced by ballon dilatation as primary treatment. Boys had a significantly higher number of esophageal procedures than girls, but the incidence of endoscopic treatments in relation to anastomoses was the same for both genders.

Conclusion The low incidence of EA in relation to a relatively large number of units treating those patients in Germany may pose challenges for maintaining competency and training of all specialists involved. The number of esophagoscopic treatments for esophageal stricture per anastomosis is lower than previously estimated.
Patients Report Infrequent Counseling by Physicians and Inadequate Knowledge about Inflammatory Bowel Disease and Reproductive Health Issues
Authors: Rao Aarti K. , Zikos Thomas A. , Garay Gotzone , Lee Ko-Eun , Streett Sarah E.
Published: December 2021

Objective Inflammatory bowel disease (IBD) reproductive health counseling is associated with higher knowledge, lower voluntary childlessness, greater medication adherence during pregnancy, and improved outcomes of pregnancy. Our aims were to assess counseling and knowledge about IBD and reproductive health in a tertiary care IBD patient population.

Study Design We anonymously surveyed women and men ages 18 to 45 cared for at the Stanford IBD clinic about reproductive health and administered the CCPKnow questionnaire. STATA was used to summarize descriptive statistics and compare categorical variables using Fisher's exact test.

Results Of the 100 patients (54% women) who completed the survey, only 33% reported prior reproductive health counseling. Both men and women considered not having a child due to IBD (31% women, 15% men) and most (83%) had no prior counseling. A minority of patients had an adequate (≥8/17) CCPKnow score (45% women, 17% men). The majority of women with prior pregnancy had pre-existing IBD (67%), yet many did not seek gastrointestinal (GI) care (38% preconception, 25% during pregnancy) and 33% stopped/changed medications, with 40% not discussing this with a physician. Prior counseling was significantly associated with education level (p = 0.013), biologic use (p = 0.003), and an adequate CCPKnow score (p = 0.01). Overall, 67% of people wanted more information on IBD and reproductive health.

Conclusion In an educated tertiary care cohort, the majority of patients had low CCPKnow scores and rates of IBD reproductive health counseling. Many patients with IBD prior to pregnancy reported no GI care preconception or during pregnancy and stopped/changed medications without consulting a physician. There is an urgent need for proactive counseling by gastroenterologists and obstetricians on IBD and reproductive health.

Key Points
Vena Cava Thrombosis after Congenital Diaphragmatic Hernia Repair: Multivariate Analysis of Potential Risk Factors
Authors: Kiblawi Rim , Zoeller Christoph , Pirr Sabine , Hofmann Alejandro D. , Ure Benno , Dingemann Jens
Published: December 2021

Introduction The treatment of newborns with congenital diaphragmatic hernia (CDH) is associated with a significant complication rate. Information on major thrombotic complications and their incidence in newborns with CDH is lacking. The aims of our analysis were to evaluate the frequency of vena cava thrombosis and to determine its predictors within a consecutive series of patients with CDH.

Materials and Methods We retrospectively analyzed charts of all neonates of our department that underwent CDH repair from 2007 to 2021, focusing on vena cava thrombosis. Vena cava thrombosis was diagnosed sonographically and classified as complete or partial venous occlusion. Complete occlusion was confirmed by cavography. Variables evaluated were CDH side, liver position, central vein line, surgical approach, and extracorporeal membrane oxygenation (ECMO). Univariate and multivariate tests were utilized.

Results Among 57 neonates who underwent CDH repair, vena cava thrombosis was diagnosed in 14 (24.6%), seven of whom had complete occlusion of the vena cava. Factors associated with vena cava thrombosis were femoral or saphenous venous catheter (p = 0.044), right sided CDH (p = 0.027) and chylothorax (p < 0.0001). ECMO was not associated with vena cava thrombosis. Seven patients (50%) with vena cava thrombosis were treated interventionally with angioplasty and seven (50%) conservatively with anticoagulation only. Mortality was not higher in patients with compared with patients without vena cava thrombosis.

Conclusion The incidence of vena cava thrombosis in newborns with CDH in our series is high. Routine postoperative abdominal sonography focusing on vena cava thrombosis is mandatory in all patients with CDH. Patients who developed vena cava thrombosis were more likely to develop chylothorax after CDH repair. Considering the good outcome of medical therapy of partial vena cava thrombosis, it may be discussed whether low dose anticoagulation may be provided to all newborns with CDH.
Pilot project purgatory? Assessing automated vehicle pilot projects in U.S. cities
Authors: McAslan Devon , Najar Arevalo Farah , King David A. , Miller Thaddeus R.
Published: December 2021

Pilot projects have emerged in cities globally as a way to experiment with the utilization of a suite of smart mobility and emerging transportation technologies. Automated vehicles (AVs) have become central tools for such projects as city governments and industry explore the use and impact of this emerging technology. This paper presents a large-scale assessment of AV pilot projects in U.S. cities to understand how pilot projects are being used to examine the risks and benefits of AVs, how cities integrate these potentially transformative technologies into conventional policy and planning, and how and what they are learning about this technology and its future opportunities and risks. Through interviews with planning practitioners and document analysis, we demonstrate that the approaches cities take for AVs differ significantly, and often lack coherent policy goals. Key findings from this research include: (1) a disconnect between the goals of the pilot projects and a city’s transportation goals; (2) cities generally lack a long-term vision for how AVs fit into future mobility systems and how they might help address transportation goals; (3) an overemphasis of non-transportation benefits of AV pilots projects; (4) AV pilot projects exhibit a lack of policy learning and iteration; and (5) cities are not leveraging pilot projects for public benefits. Overall, urban and transportation planners and decision makers show a clear interest to discover how AVs can be used to address transportation challenges in their communities, but our research shows that while AV pilot projects purport to do this, while having numerous outcomes, they have limited value for informing transportation policy and planning questions around AVs. We also find that AV pilot projects, as presently structured, may constrain planners’ ability to re-think transportation systems within the context of rapid technological change.
Social work practices and enabling the integration of students from war and conflict zones
Authors: Snoubar Yaser
Published: December 2021

Until recently, few studies have examined international students’ social issues and well-being from war and conflict zones. A significant proportion of international students in Turkey have arrived from countries actively engaged in conflict; however, it is unclear how social work procedures have effectively addressed students’ needs and ability to cope after migrating. This quantitative study aimed to identify the challenges and well-being issues of 63 Syrian students who have recently integrated into Turkey. The investigation took place at Ankara Yildirim Beyazit University in Turkey, during the 2017–2018 academic year. The research is based on two measurement scales and a questionnaire. Results were analyzed using independent t-test samples and found that social workers faced challenges in integrating the students. A lack of participation in social activities and cultural challenges are common problems faced by these students. Traditional support methods were effective strategies for overcoming new social environments. The effectiveness of social work intervention is reviewed further.
VIZSLA—Versatile Ice Zigzag Sublimation Setup for Laboratory Astrochemistry
Authors: Bazsó Gábor , Csonka István Pál , Góbi Sándor , Tarczay György
Published: December 2021

In this article, a new multi-functional high-vacuum astrophysical ice setup, VIZSLA (Versatile Ice Zigzag Sublimation Setup for Laboratory Astrochemistry), is introduced. The instrument allows for the investigation of astrophysical processes both in a low-temperature para-H2 matrix and in astrophysical analog ices. In the para-H2 matrix, the reaction of astrochemical molecules with H atoms and H+ ions can be studied effectively. For the investigation of astrophysical analog ices, the setup is equipped with various irradiation and particle sources: an electron gun for modeling cosmic rays, an H atom beam source, a microwave H atom lamp for generating H Lyman-α radiation, and a tunable (213–2800 nm) laser source. For analysis, an FT-IR (and a UV–visible) spectrometer and a quadrupole mass analyzer are available. The setup has two cryostats, offering novel features for analysis. Upon the so-called temperature-programmed desorption (TPD), the molecules, desorbing from the substrate of the first cryogenic head, can be mixed with Ar and can be deposited onto the substrate of the other cryogenic head. The efficiency of the redeposition was measured to be between 8% and 20% depending on the sample and the redeposition conditions. The well-resolved spectrum of the molecules isolated in an Ar matrix serves a unique opportunity to identify the desorbing products of a processed ice. Some examples are provided to show how the para-H2 matrix experiments and the TPD–matrix-isolation recondensation experiments can help understand astrophysically important chemical processes at low temperatures. It is also discussed how these experiments can complement the studies carried out by using similar astrophysical ice setups.
Accurate parameterization of the kinetic energy functional
Authors: Kumar Shashikant , Borda Edgar Landinez , Sadigh Babak , Zhu Siya , Hamel Sebastian , Gallagher Brian , Bulatov Vasily , Klepeis John , Samanta Amit
Published: December 2021

The absence of a reliable formulation of the kinetic energy density functional has hindered the development of orbital free density functional theory. Using the data-aided learning paradigm, we propose a simple prescription to accurately model the kinetic energy density of any system. Our method relies on a dictionary of functional forms for local and nonlocal contributions, which have been proposed in the literature, and the appropriate coefficients are calculated via a linear regression framework. To model the nonlocal contributions, we explore two new nonlocal functionals—a functional that captures fluctuations in electronic density and a functional that incorporates gradient information. Since the analytical functional forms of the kernels present in these nonlocal terms are not known from theory, we propose a basis function expansion to model these seemingly difficult nonlocal quantities. This allows us to easily reconstruct kernels for any system using only a few structures. The proposed method is able to learn kinetic energy densities and total kinetic energies of molecular and periodic systems, such as H2, LiH, LiF, and a one-dimensional chain of eight hydrogens using data from Kohn–Sham density functional theory calculations for only a few structures.
Vertical field inhomogeneity associated with threading dislocations in GaN high electron mobility transistor epitaxial stacks
Authors: Wohlfahrt Markus , Uren Michael J. , Yin Yidi , Lee Kean Boon , Kuball Martin
Published: December 2021

A measurement technique combining Kelvin-probe force microscopy with substrate bias is developed and demonstrated on AlGaN/GaN-on-Si device structures under conditions relevant to the effect of off-state drain bias stress in transistors. For a high substrate bias, the measurements show a significantly lowered surface potential surrounding a small proportion of dislocations imaged with atomic force microscopy (AFM), laterally extending on a scale of up to a micrometer. Both the density and the size of those features increase with substrate bias; however, conductive AFM measurements under the same bias conditions showed no leakage reaching the surface associated with those features. Our model considers localized conductive paths that end a certain distance below the 2D electron gas electrically “thinning” the epitaxy and, therefore, deforming the potential and increasing the electric field under off-state stress bias. The conclusion is that the vertical electric field in the buffer is laterally highly non-uniform with an enhanced vertical field in the vicinity of those dislocations. This non-uniformity redirects the substrate bias stress from the buffer to the channel with potential consequences for breakdown.
Spectral properties of polycrystalline MoS2 films grown by RF magnetron sputtering
Authors: Jarosiński Ł. , Kollbek K. , Marciszko-Wiąckowska M. , Gajewska M. , Jeleń P. , Szaciłowski K. , Przybylski M.
Published: December 2021

Molybdenum disulfide (MoS2) polycrystalline thin films of different thicknesses have been deposited by radio frequency magnetron sputtering and then post-annealed. The resonant and non-resonant Raman spectra consist of broadened, insignificantly shifted peaks, pointing out that the atomic structure of MoS2 in thin films is preserved. X-ray diffraction and high-resolution transmission electron microscopy suggest that the mean crystallite size of MoS2 thin films ranges from 2.8 to 4.2 nm with increasing film thickness. The blue shift in the optical absorption spectra with the decreasing mean crystallite size and decreasing layer thickness provides tailorability of the bandgap. The increase in the effective bandgap from 1.6 to 1.9 eV is apparent with the reduction in film thickness from 24 to 1.5 nm. It can be seen that even for thick films, whose thickness can be compared to the bulk sample, the value of the effective bandgap is higher than 1.2 eV, as reported for bulk MoS2. It is presumed that this effect could be attributed to the quantum size effect exerted by two types of energy barriers: grain boundaries and layer surfaces. The experimentally measured bandgap of MoS2 thin films is compared with the predictions of the effective mass approximation and the hyperbolic band approximation models for the crystallites building up the films.
Evidence of the dominant production mechanism of ammonia in a hydrogen plasma with parts per million of nitrogen
Authors: Ellis J. , Köpp D. , Lang N. , van Helden J. H.
Published: December 2021

Absolute ground state atomic hydrogen densities were measured, by the utilization of two-photon absorption laser induced fluorescence, in a low-pressure electron cyclotron resonance plasma as a function of nitrogen admixtures—0 to 5000 ppm. At nitrogen admixtures of 1500 ppm and higher, the spectral distribution of the fluorescence changes from a single Gaussian to a double Gaussian distribution; this is due to a separate, nascent contribution arising from the photolysis of an ammonia molecule. At nitrogen admixtures of 5000 ppm, the nascent contribution becomes the dominant contribution at all investigated pressures. Thermal loading experiments were conducted by heating the chamber walls to different temperatures; this showed a decrease in the nascent contributions with increasing temperature. This is explained by considering how the temperature influences recombination coefficients, and from which, it can be stated that the Langmuir–Hinshelwood recombination mechanism is dominant over the Eley–Rideal mechanism.
Simulating the nematic-isotropic phase transition of liquid crystal model via generalized replica-exchange method
Authors: Takemoto Kengo , Ishii Yoshiki , Washizu Hitoshi , Kim Kang , Matubayasi Nobuyuki
Published: December 2021

The nematic-isotropic (NI) phase transition of 4-cyano-4′-pentylbiphenyl was simulated using the generalized replica-exchange method (gREM) based on molecular dynamics simulations. The effective temperature is introduced in the gREM, allowing for the enhanced sampling of configurations in the unstable region, which is intrinsic to the first-order phase transition. The sampling performance was analyzed with different system sizes and compared with that of the temperature replica-exchange method (tREM). It was observed that gREM is capable of sampling configurations at sufficient replica-exchange acceptance ratios even around the NI transition temperature. A bimodal distribution of the order parameter at the transition region was found, which is in agreement with the mean-field theory. In contrast, tREM is ineffective around the transition temperature owing to the potential energy gap between the nematic and isotropic phases.
Zn-doped NiSe2@Ni(OH)2 nanocomposites as binder-free electrodes for asymmetric supercapacitors with impressive performance
Authors: Lei Xueyan , Fu Zhengping , Xiang Bin , Lu Yalin
Published: December 2021

The low stability and poor activities of transition metal selenides (TMSs) in alkaline electrolyte limit their application in supercapacitors. Metal doping and hybridization of various electroactive materials with different properties are utilized to enhance the electrochemical performance of TMSs by optimizing their electronic structure and providing rich electrochemical active sites. Herein, we report a simple two-step hydrothermal method for the growth of Zn-doped NiSe2 and Ni(OH)2 nanocomposites on Ni foam [Zn–NiSe2/Ni(OH)2]. The resulting material delivers high specific capacity (1525.8 C g−1/564.7 mA h g−1 at 6 A g−1 and 1220 C g−1 at 10 A g−1) in a three-electrode system. A Zn–NiSe2/Ni(OH)2//porous carbon (PC) aqueous asymmetric supercapacitor (ASC) was built by utilizing Zn–NiSe2/Ni(OH)2 as the positive electrode and PC as the negative electrode. This Zn–NiSe2/Ni(OH)2//PC ASC shows an energy density of 75.8 W h kg−1 at a power density of 916.1 W kg−1 and achieves a specific capacity retention of 100% after 25 000 cycles at 10 A g−1. These results reveal that the Zn doping and the hybridization of NiSe2 with Ni(OH)2 can obtain impressive electrochemical properties in ASCs.
Enhancing energy storage performances in an ultra-wide temperature range via interface engineering and thermal management for silicon-integrated dielectric capacitors
Authors: Jin Jing , Ma Chuansheng , Hu Guangliang , Lu Lu , Liang Zhongshuai , Zhao Wanli , Liu Yutong , Ma Chunrui , Liu Ming
Published: December 2021

High-performance silicon-integrated dielectric thin film capacitors with superior thermal stability are strongly attractive for application in integrated circuits and electronic devices. Here, by combining interface engineering with thermal management, lead-free 0.85BaTiO3-0.15Bi(Mg0.5Zr0.5)O3 (BT-BMZ) dielectric thin film capacitors were integrated on Si, HfO2-buffered Si (HfO2/Si), and graphene-buffered HfO2/Si (G/HfO2/Si) substrates. Benefiting from not only high-quality interface between HfO2 and Si but also the heat dissipation effect of the graphene layer, an ultra-high energy storage density up to 102 J/cm3 with an efficiency of 74.57% was obtained in BT-BMZ/G/HfO2/Si at room temperature. More importantly, the optimized capacitor exhibited an ultra-stable energy density of 52.1 J/cm3 (±10%) with high efficiency (over 70%) in a wide temperature range of –100 to 175 °C, greatly broadening the working temperature in comparison to BT-BMZ/Si (–100 to 100 °C). The present research provides a scalable strategy to enhance energy storage performance of dielectric capacitors, especially at elevated temperatures.
Step consistency active control method for inertial piezoelectric actuator using embedded strain gauges
Authors: Cheng Jianfei , Deng Jie , Liu Yingxiang , Zhang Shijing , Lu Fei , Tian Xinqi , Chen Weishan
Published: December 2021

Inertial piezoelectric actuators (IPAs) are widely used in micro–nano manipulation, biomedicine, and other fields as the simple structure and excitation signal. However, the step consistency is difficult to guarantee in a large stroke range due to the limited machining accuracy of the mover and inherent roll back, which limits the practical application in these precision fields. Therefore, a step consistency active control method for IPAs is proposed based on bending hybrid motions, which uses embedded strain gauges as the force sensors to acquire the pressure between the mover and the actuator. The IPA is driven by horizontal bending motion, and the pressure can be dynamically adjusted by vertical bending motion to ensure the constant pressure and achieve a constant step. Experiments results show that the maximum standard deviation of the step is 0.41 µm under the active control of 350 Vp–p and 1 Hz driving voltage within 2 mm stroke range in 500 driving cycles, and the maximum standard deviation of the step is 1.14 µm under the non-active control with the same conditions, which show that the proposed method evidently improves the step consistency of IPA in a large stroke range.
Emission spectroscopy of negative hydrogen ion sources: From VUV to IR
Authors: Wünderlich D. , Briefi S. , Friedl R. , Fantz U.
Published: December 2021

The target parameters of negative ion sources regarding the current of extracted negative ions, the current of co-extracted electrons, the pulse duration, the duty cycle, and the availability of the system can be rather strict. Knowledge of plasma parameters such as the electron temperature and the electron density and also properties of molecules or photon fluxes can provide essential insights into the ion source physics needed for reaching the target parameters. Emission spectroscopy is a non-invasive tool enabling access to line-of-sight averaged values of plasma parameters. This paper gives an overview of the application of emission spectroscopy in the visible range, extended for long wavelengths to the near-IR and for short wavelengths to the vacuum ultraviolet (VUV)/UV range. The amount of information to be gained from measured emission spectra is directly correlated with the effort invested for calibrating the system. Examples are given, ranging from simple monitoring to the complex evaluation of molecular spectra and the determination of highly energetic photon fluxes in the VUV/UV range. Additional emphasis is laid on the population models needed for the interpretation of measured spectra.
Thermal control of transonic shock-boundary layer interaction over a natural laminar flow airfoil
Authors: Sengupta Tapan K. , Roy Arkadyuti Ghosh , Chakraborty Ardhendu , Sengupta Aditi , Sundaram Prasannabalaji
Published: December 2021

Implicit large eddy simulations are performed to show control of shock and boundary layer interaction over a natural laminar flow airfoil by harmonic heat transfer on the suction surface at a free-stream Mach number M∞=0.72 and angle of attack of α=0.38°, for which experimental/flight test results exist. Surface heat flux is added in a time-periodic manner with the exciter strip located at different locations in the vicinity of the shock location at x/c≈0.49 for the flow without any control. Four cases of localized excitation with Gaussian distribution centered at x/c=0.45, 0.48, 0.50, and 0.55 on the airfoil surface are considered, with a width of 10% chord. The effects of unsteady heat flux on shock strength, location, and modification of its structure are demonstrated by instantaneous and time-averaged flow quantities. Detailed vortical and entropy contour plots and numerical Schlieren indicate flow features, such as creation and propagation of Kutta waves and their interactions with the shock wave. Time-averaged load distributions reveal a shift in the location and strength of the shock, with altered lift and drag time histories. The Fourier transforms of lift and drag coefficients help explain the alteration of the strength and structures of the shock-induced unsteadiness. The imposed excitation results in an improvement of aerodynamic efficiency (lift to drag ratio). The numerical simulations follow the algorithm developed in Sengupta et al. [Comput. Fluids 88, 19–37 (2013)].
Ohmic contact on low-doping-density p-type GaN with nitrogen-annealed Mg
Authors: Lu Shun , Deki Manato , Wang Jia , Ohnishi Kazuki , Ando Yuto , Kumabe Takeru , Watanabe Hirotaka , Nitta Shugo , Honda Yoshio , Amano Hiroshi
Published: December 2021

We have demonstrated a fabrication process for the Ohmic contact on low-doping-density p-type GaN with nitrogen-annealed Mg. An Ohmic contact with a contact resistance of 0.158 Ω cm2 is realized on p−-GaN ([Mg] = 1.3 × 1017 cm−3). The contact resistance of p-type GaN with higher Mg concentration ([Mg]=1.0 × 1019 cm−3) can also be reduced to 2.8 × 10−5 Ω cm2. A localized contact layer is realized without any etching or regrowth damage. The mechanism underlying this reduced contact resistance is studied by scanning transmission electron microscopy with energy dispersive x-ray spectroscopy and secondary ion mass spectrometry, representing a mutual diffusion of Ga and Mg atoms on the interface. Reductions in the barrier height and surface depletion width with the nitrogen-annealed Mg layer are confirmed by XPS and Hall effect measurements qualitatively.
Accurate scaling functions of the scaled Schrödinger equation
Authors: Nakatsuji Hiroshi , Nakashima Hiroyuki , Kurokawa Yusaku I.
Published: December 2021

The scaling function g of the scaled Schrödinger equation (SSE) is generalized to obtain accurate solutions of the Schrödinger equation (SE) with the free complement (FC) theory. The electron–nuclear and electron–electron scaling functions, giA and gij, respectively, are generalized. From the relations between SE and SSE at the inter-particle distances being zero and infinity, the scaling function must satisfy the collisional (or coalescent) condition and the asymptotic condition, respectively. Based on these conditions, general scaling functions are classified into “correct” (satisfying both conditions), “reasonable” (satisfying only collisional condition), and “approximate but still useful” (not satisfying collisional condition) classes. Several analytical scaling functions are listed for each class. Popular functions riA and rij belong to the reasonable class. The qualities of many electron–electron scaling functions are examined variationally for the helium atom using the FC theory. Although the complement functions of FC theory are produced generally from both the potential and kinetic operators in the Hamiltonian, those produced from the kinetic operator were shown to be less important than those produced from the potential operator. Hence, we used only the complement functions produced from the potential operator and showed that the correct-class gij functions gave most accurate results and the reasonable-class functions were less accurate. Among the examined correct and reasonable functions, the conventional function rij was worst in accuracy, although it was still very accurate. Thus, we have many potentially accurate “correct” scaling functions for use in FC theory to solve the SEs of atoms and molecules.
Solarity and connectedness of sets in the space

and in finite-dimensional polyhedral spaces
Authors: Tsar’kov I. G.
Published: December 2021

Generalized

-piecewise functions constructed from given monotone path-connected boundedly compact subsets of the space

are studied. They are shown to be monotone path-connected suns. In finite-dimensional polyhedral spaces, luminosity points of sets admitting a lower semicontinuous selection of the metric projection operator are investigated. An example of a non-

-connected sun in a four-dimensional polyhedral normed space is constructed.

Bibliography: 14 titles.
A Chisini Theorem for almost generic covers of the projective plane
Authors: Kulikov Vik. S.
Published: December 2021

Results related to Chisini’s Conjecture and contained in (Izv. Math.
63:6 (1999), 1139–1170) and (Izv. Math.
65:1 (2001), 71–74) are extended to the case of almost generic covers of the projective plane.

Bibliography: 11 titles.
Vinogradov’s sieve and an estimate for an incomplete Kloosterman sum
Authors: Korolev M. A.
Published: December 2021

We refine a bound for a short Kloosterman sum with a prime modulususing the so-called Vinogradov sieve. The number of terms in the sum can be less than an arbitrarily small fixed power of.

Bibliography: 26 titles.
Topological classification of billiards bounded by confocal quadrics in three-dimensional Euclidean space
Authors: Belozerov G. V.
Published: December 2021

We study billiards on compact connected domains in

bounded by a finite number of confocal quadrics meeting in dihedral angles equal to

. Billiards in such domains are integrable due to having three first integrals in involution inside the domain. We introduce two equivalence relations: combinatorial equivalence of billiard domains determined by the structure of their boundaries, and weak equivalence of the corresponding billiard systems on them. Billiard domains in

are classified with respect to combinatorial equivalence, resulting in 35 pairwise nonequivalent classes. For each of these obtained classes, we look for the homeomorphism class of the nonsingular isoenergy 5-manifold, and we show this to be one of three types: either

, or

, or

. We obtain 24 classes of pairwise nonequivalent (with respect to weak equivalence) Liouville foliations of billiards on these domains restricted to a nonsingular energy level. We also define bifurcation atoms of three-dimensional tori corresponding to the arcs of the bifurcation diagram.

Bibliography: 59 titles.
On the cohomology rings of partially projective quaternionic Stiefel manifolds
Authors: Zhubanov G. E. , Popelenskii F. Yu.
Published: December 2021

The quaternionic Stiefel manifold

is the total space of a fibre bundle over the corresponding Grassmannian

. The group

acts freely on the fibres of this bundle. The quotient space is called the quaternionic projective Stiefel manifold. Its real and complex analogues were actively studied earlier by a number of authors. A finite group acting freely on the three-dimensional sphere also acts freely and discretely on the fibres of the quaternionic Stiefel bundle. The corresponding quotient spaces are called partially projective Stiefel manifolds.

The cohomology rings of partially projective quaternionic Stiefel manifolds with coefficients in

, where

is prime, are calculated.

Bibliography: 14 titles.
Application of an economic evaluation approach to making regulatory decisions regarding access to medicines: advantages, challenges and recommendations
Authors: Parkinson Bonny , Cutler Henry
Published: December 2021

Initially patients require a prescription to access most new medicines. Some medicines may later be reclassified, allowing patients to access them without a prescription. Currently, Australian Therapeutic Goods Administration guidelines regarding reclassification decisions focus on patient risk rather than on potential benefits to patient health and the healthcare system. We conducted two extensive case studies demonstrating an economic evaluation approach to medicine reclassification in Australia, which were presented at various conferences and to key stakeholders. This article discusses the advantages and challenges of using an economic evaluation approach to inform medicine reclassification decisions. Advantages identified include systematically and transparently synthesising evidence from multiple sources; predicting the overall expected impact of reclassification on health outcomes and costs before it occurs; considering a broader range of risks and benefits; aggregation of health impacts into a single measure (quality-adjusted life years); identification of drivers of uncertainty; insight into the effects of different regulatory decisions; and improved consistency of evidence. Challenges include data availability and quality, estimating behavioural changes, model complexity, the lack of an incremental cost-effectiveness ratio threshold, and funding of economic analyses. We recommend that regulatory decision makers use an economic evaluation approach to help inform reclassification decisions, although economic evaluation results should be considered as part of the broader body of evidence. Ultimately, the use of an economic evaluation approach will contribute to helping decision makers maximise population health outcomes in an efficient way. What is known about the topic? In the past, decisions regarding medicine reclassification have generally been made using a deliberative approach focusing on patient risk. However, there are also potential benefits to patient health and effects on the healthcare system. Increasing awareness of these benefits have led to the development of alternative approaches to decision making, including an economic evaluation approach. What does this paper add? This article discusses the advantages and challenges of using an economic evaluation approach to inform medicine reclassification decisions compared with alternative approaches. What are the implications for practitioners? Economic evaluation results should be considered as part of the broader body of evidence regarding the types of health impacts, the extent of the available evidence, who will be affected, and the role of medical practitioners and pharmacists in mitigating any risks. However, awareness of the advantages and challenges of this approach in advance will help mitigate some of the challenges and increase acceptance of the economic evaluation results by decision makers and stakeholders.