bluuebunny/crossref_metadata_2025 huggingface dataset:
The “Maggie” filament: Physical properties of a giant atomic cloud
Authors: Syed J. , Soler J. D. , Beuther H. , Wang Y. , Suri S. , Henshaw J. D. , Riener M. , Bialy S. , Rezaei Kh. S. , Stil J. M. , Goldsmith P. F. , Rugel M. R. , Glover S. C. O. , Klessen R. S. , Kerp J. , Urquhart J. S. , Ott J. , Roy N. , Schneider N. , Smith R. J. , Longmore S. N. , Linz H.
Published: November 2021

Context. The atomic phase of the interstellar medium plays a key role in the formation process of molecular clouds. Due to the line-of-sight confusion in the Galactic plane that is associated with its ubiquity, atomic hydrogen emission has been challenging to study.

Aims. We investigate the physical properties of the “Maggie” filament, a large-scale filament identified in H I emission at line-of-sight velocities, vLSR ~−54 km s−1.

Methods. Employing the high-angular resolution data from The H I/OH Recombination line survey of the inner Milky Way (THOR), we have been able to study H I emission features at negative vLSR velocities without any line-of-sight confusion due to the kinematic distance ambiguity in the first Galactic quadrant. In order to investigate the kinematic structure, we decomposed the emission spectra using the automated Gaussian fitting algorithm GAUSSPY+.

Results. We identify one of the largest, coherent, mostly atomic H I filaments in the Milky Way. The giant atomic filament Maggie, with a total length of 1.2 ± 0.1 kpc, is not detected in most other tracers, and it does not show signs of active star formation. At a kinematic distance of 17 kpc, Maggie is situated below (by ≈500 pc), but parallel to, the Galactic H I disk and is trailing the predicted location of the Outer Arm by 5−10 km s−1 in longitude-velocity space. The centroid velocity exhibits a smooth gradient of less than ±3 km s−1 (10 pc)−1 and a coherent structure to within ±6 km s−1. The line widths of ~10 km s−1 along the spine of the filament are dominated by nonthermal effects. After correcting for optical depth effects, the mass of Maggie’s dense spine is estimated to be 7.2−1.9+2.5 × 105 M⊙. The mean number density of the filament is ~4 cm−3, which is best explained by the filament being a mix of cold and warm neutral gas. In contrast to molecular filaments, the turbulent Mach number and velocity structure function suggest that Maggie is driven by transonic to moderately supersonic velocities that are likely associated with the Galactic potential rather than being subject to the effects of self-gravity or stellar feedback. The probability density function of the column density displays a log-normal shape around a mean of ⟨NH I⟩ = 4.8 × 1020 cm−2, thus reflecting the absence of dominating effects of gravitational contraction.

Conclusions. While Maggie’s origin remains unclear, we hypothesize that Maggie could be the first in a class of atomic clouds that are the precursors of giant molecular filaments.
Revisiting the explodability of single massive star progenitors of stripped-envelope supernovae
Authors: Zapartas E. , Renzo M. , Fragos T. , Dotter A. , Andrews J. J. , Bavera S. S. , Coughlin S. , Misra D. , Kovlakas K. , Román-Garza J. , Serra J. G. , Qin Y. , Rocha K. A. , Tran N. H. , Xing Z. P.
Published: November 2021

Stripped-envelope supernovae (Types IIb, Ib, and Ic) that show little or no hydrogen comprise roughly one-third of the observed explosions of massive stars. Their origin and the evolution of their progenitors are not yet fully understood. Very massive single stars stripped by their own winds (≳25−30 M⊙ at solar metallicity) are considered viable progenitors of these events. However, recent 1D core-collapse simulations show that some massive stars may collapse directly into black holes after a failed explosion, with a weak or no visible transient. In this Letter, we estimate the effect of direct collapse into a black hole on the rates of stripped-envelope supernovae that arise from single stars. For this, we compute single-star MESA models at solar metallicity and map their final state to their core-collapse outcome following prescriptions commonly used in population synthesis. According to our models, no single stars that have lost their entire hydrogen-rich envelope are able to explode, and only a fraction of progenitors left with a thin hydrogen envelope do (IIb progenitor candidates), unless we use a prescription that takes the effect of turbulence into account or invoke increased wind mass-loss rates. This result increases the existing tension between the single-star paradigm to explain most stripped-envelope supernovae and their observed rates and properties. At face value, our results point toward an even higher contribution of binary progenitors to stripped-envelope supernovae. Alternatively, they may suggest inconsistencies in the common practice of mapping different stellar models to core-collapse outcomes and/or higher overall mass loss in massive stars.
Multifilter photometry of Solar System objects from the SkyMapper Southern Survey
Authors: Sergeyev A. V. , Carry B. , Onken C. A. , Devillepoix H. A. R. , Wolf C. , Chang S.-W.
Published: November 2021

Context. The populations of small bodies of the Solar System (asteroids, comets, and Kuiper Belt objects) are used to constrain the origin and evolution of the Solar System. Their orbital distribution and composition distribution are both required to track the dynamical pathway from their formation regions to their current locations.

Aims. We aim to increase the sample of Solar System objects (SSOs) that have multifilter photometry and compositional taxonomy.

Methods. We searched for moving objects in the SkyMapper Southern Survey. We used the predicted SSO positions to extract photometry and astrometry from the SkyMapper frames. We then applied a suite of filters to clean the catalog from false-positive detections. We finally used the near-simultaneous photometry to assign a taxonomic class to objects.

Results. We release a catalog of 880 528 individual observations, consisting of 205 515 known and unique SSOs. The catalog completeness is estimated to be about 97% down to V = 18 mag and the purity is higher than 95% for known SSOs. The near-simultaneous photometry provides either three, two, or a single color that we use to classify 117 356 SSOs with a scheme consistent with the widely used Bus-DeMeo taxonomy.

Conclusions. The present catalog contributes significantly to the sample of asteroids with known surface properties (about 40% of main-belt asteroids down to an absolute magnitude of 16). We will release more observations of SSOs with future SkyMapper data releases.
Experimental Pullout Capacity of Screw Piles in Dry Gypseous Soil
Authors: Karkush Mahdi O. , Mukhlef Omar J.
Published: November 2021

Screw piles are widely used in supporting structures subjected to pullout forces, such as power towers and offshore structures, and this research investigates their performance in gypseous soil of medium relative density. The bearing capacity and displacement of a single screw pile model inserted in gypseous soil with various diameters (D = 20, 30, and 40) mm are examined in this study. The soil used in the testing had a gypsum content of 40% and the bedding soil had a relative density of 40%. To simulate the pullout testing in the lab, a physical model was manufactured with specific dimensions. Three steel screw piles with helix diameters of 20, 30, and 40 mm are used, with a total length of 500 mm. The helix is continuous over the pile's embedded depth of 400 mm. The results of tests revealed that decreasing the length to diameter (H/D) ratio resulted in a higher pullout capacity of screw piles and a lower corresponding displacement.
Settlement of Ring Footing Resting on Geocell Reinforced Sandy Soil under Cyclic Load
Authors: Fattah Mohammed Y. , Al-Neami Mohammed A. , Mohammed Sadan A.
Published: November 2021

Ring footings are widely used as a foundation for water tanks, television antennas, silos, chimneys, oil storage tanks, etc. This paper is conducted to study the ring footing model's experimental cyclic behavior and circular footing resting on sandy soil reinforced with geocell. A group of ninety-six test models has been tested to investigate shallow footings' behavior beneath a cyclic loading of various loading rates. Four shapes of footing sand with three relative densities, two embedment depths of footing, two loading rates, and two widths of geocell were used. It was founded that as the footing depth increases, the settlement of soil due to cyclic loading decreases. Generally, when other variables are maintained to be the same, the footing bearing capacity increases when the foundation depth increases. The footing rebounds to some degree during the decay period of the load. The presence of geocell at the footing depth equals 100 mm will provide more improvement in all footing models more than using it at the surface, especially in ring 2 where the radius ratio is 0.4.
Effect of Spacing between Stone Columns on the Behavior of Soft Soil
Authors: Al-Kazzaz Zeena A. , Al-Obaydi Moataz A.
Published: November 2021

Soil improvement by stone columns is extensively used, especially for the soft ones. This is because of their efficiency and no environmental impact. Several factors affect its efficiency in improving the mechanical properties of the soil, and the most important of these factors are the spacing, length, and diameter of the stone columns. In this study, the finite element method was used to study the impact of the spacing between the stone columns on the amount of settlement and the bearing capacity of the soil. The study comprises three different spaces (s) that were taken in relation to the columns’ diameter (d), which are (s/d= 3, 4, and 5). In addition, three types of the sectional shape of column involved circular, rectangular, and square sections with different lengths of (L/d=2, 4, 6, 8, and 10). The results showed that the spacing between the stone columns is effective when the vertical load is greater than 30 kN/m2, and below this, there is no effect of the spacing. In general, the settlement decreases, and the bearing capacity increases with the decrease in the spacing between the stone columns. The spacing becomes a more pronounced effect with the longer length of the stone columns. All sections of the stone columns with a short length of (L/d=2) showed the same settlement of 271 mm at a distance (s/d=5), which decreases by 7.4, 6.6, and 8.9% at a distance (s/d=3) for the circular, rectangular and square sections respectively. In the case of long columns (L/d=10), the settlement at (s/d=3) improves by about 27.5% which drop to about 18% at (s/d=5). A slight improvement in the soil's bearing capacity is associated with decreases in the spacing between the stone columns. The improvements in the bearing of soil treated with short columns (L/d=2) are 6.0, 6.5, and 4.7% for circular, rectangular, and square sections, respectively, when changing the distance from (s/d=5) to (s/d=3). Whereas they become greater when increasing the columns’ length to (L/d=10) to be 7.9, 9.2, and 6.4%.
Bearing Capacity Behavior of Skirted Foundations on Unsaturated Soils
Authors: Mohammed Muthana S. , Mahmood Mahmood R. , Al-Wakel Saad F. A.
Published: November 2021

One of the most important factors for designing a safe foundation is the amount of bearing soil capacity and allowable settlement according to the type of structure. Therefore, in geotechnical engineering, the aim is to improve foundations' bearing capacity in many ways, some of which are expensive, and the other section is difficult to implement in some sites. Skirted foundations consider as an ideal solution to improve cost-wise soil tolerance by reducing materials and installation time. At present, there are several applications, including offshore platforms, bridges, turbines, oil installations, and high-load facilities. This paper investigates the behavior of carrying capacity of skirted foundations through experimental models on the sand. To examine the effect of various saturation conditions, various ratios of length to width of the footing base at different relative densities and different conditions for saturations dry, saturated, and partially saturated soils are considered. It was found that the magnitude of soil bearing enhances with increasing ratios of length to the width of the base of the footings for all cases. The increase in performance ratio increased linearly to 1.5 in footing depth (D/B) and then decreased according to the test results after this point.
Investigation the Opportunity of BIM with Agile Management Approach in Iraqi Construction Projects
Authors: Ahmed Ghassan A. , Altaie Meervat R.
Published: November 2021

The construction industry in Iraq suffers from many problems, perhaps the most important of which is the delay in time and the increase in costs. Therefore, it was necessary to try to adopt a new methodology that would help in overcoming these problems. It was suggested to combine building information modeling with the agile management approach because this technique and methodology is modern and helps in reducing time and cost and improving quality. This paper aims to know the status of using Building Information Modeling (BIM) and Agile Project management (APM) in Iraq and to shed light on the merging of this integration, explaining the benefits, difficulties, and workflow practices, finding the most influencing factors on the time, cost and quality of the project. For a comprehensive understanding, the literature was reviewed for each of BIM and Agile separately, and an initial field survey was conducted to diagnose the factors of greatest importance, and a second field survey was conducted to know the effect of the factors identified from the initial questionnaire on time, cost and quality. The results indicated the weak use of BIM in Iraq, where the non-use rate reached more than 60% and the rate may reach 75%. The agile methodology from the field survey sample is not used in this paper. The benefits that have been presented deserve to be overcome.
Selecting Appropriate Delivery System for Implementation of Green Buildings
Authors: Tamur Shaymaa T. , Erzaij Kadhim R.
Published: November 2021

Green buildings are considered more efficient than traditional buildings due to the incorporated techniques and the multidisciplinary specializations required to comply with their specifications, in addition to the advanced commissioning, which undergoes before handing over the buildings to the owners to ensure requirements conformance. As a result, the appropriate selection of a project delivery system acts as the essential factor that affects the performance of the project. This research aims at building a system that helps to select the best method to implement green buildings. Through studying the recent research approaches in project delivery systems, the factors that affect the selection of the optimal implementation method for green buildings have been identified; expert interviews have been done to study and analyze the main influential factors that affect the selection of the best method for implementing green buildings. The results of interviews indicate that the main influential factors are as follows: The occurrence of economic crises in the country, availability of financial capacity for the contractor and the owner, the lack of previous experience in similar projects, hiring an incompetent contractor, differences between design drawings among all disciplines, and providing qualified contractors, subcontractors, suppliers and craftsmen with sufficient qualifications early in the project. Depending on these main factors, a software system is built to choose the best delivery system for green building projects. This research encourages future works to focus on the quality and performance of green buildings and lays out the foundation for academic researchers to explore new techniques for evaluating the project delivery systems as well as supporting the decision-makers to choose the best.
Previous Research Works on Reinforced Concrete Curved Beams
Authors: Khaleel W. H. , Talal A. A. , Baidaa N. H. , Abdul-Razzaq K. S. , Dawood A. A.
Published: November 2021

The current research work summarizes some previous research works on horizontally curved beams. Because of curvature, torsional effects in the analysis and design should be included. Diameter of ring beam, number of supports, beam width, compressive strength of the concrete, and bearing plate width. Which can be summarized from previous studies is that increasing diameter of ring by about 25-75% decreases the capacity load by about 14-36%, while increasing number of supports by about 33-100%, beam width by about 25-75%, compressive strength of concrete by about 24-76%, and bearing plate width by about 25-75% increases the capacity load by about 62-189%, 25-75%, 24-76%, and 5-16%, respectively due to the beam section increase and/or its properties. Frequently, reinforced concrete deep ring beams exhibit shear failure in a manner similar to straight beams. Strut and tie model (STM) and plastic analysis are useful tools for efficiently analyzing ring or curved deep beams. In addition, the nonlinear three-dimensional finite element modeling is typical for predicting the deep curved beams strength and behavior.
Effect of Large Openings on the Behavior of Reinforced Concrete Continuous Deep Beams under Static and Repeated Load
Authors: Khalaf Mohammed R. , Al-Ahmed Ali Hussein A.
Published: November 2021

This paper aims to investigate the behavior of the existence of large openings on reinforced concrete continuous deep beams (RCCDBs) under static and limited cycles of repeated load. The experimental work included testing seven RCCDBs. One of these beams was solid subjected to static load, while the other beams having external shear spans, internal shear spans, and mid-span openings subjected to static and fifteen cycles of repeated loading. The range of the repeated loading was varied between a lower level and an upper level, equal to 30 and 70 percent, respectively, of the ultimate load of the beam subjected to static load. All test specimens were tested under five-point bending. For beams with large openings, 160×160 mm (which represents 40% of the overall depth of the section) openings were created symmetrically at various locations. Experimental results showed that the maximum ultimate loads of beams with large openings were decreased by about 36% for beams with large openings locating at interior shear spans compared to a solid beam. However, the maximum reduction in ultimate load of the beam with a large opening subjected to repeated load was about 6%.
Annual variation of atmospheric electricity diurnal variation maximum in Kamchatka
Authors: Smirnov Sergey
Published: November 2021

Atmospheric electric field diurnal variation measured in fair weather conditions over the ocean surface has a typical form which is called a unitary variation. It is associated with the global time and occurs simultaneously all over the planet. However, the diurnal variation, measured over the ground, depends on many local factors. The diurnal variation maximum of the electric field potential gradient, measured at Paratunka observatory, has the maximum close in time to the unitary variation maximum. In the paper we show that this maximum is determined by local conditions and is associated in time with the sunrise. The diurnal variation maximum of the electric field potential gradient, measured at Paratunka observatory in fair weather conditions, has annual variation coinciding with the annual variation of local sunrise.
Analysis of manifestation of joint acoustic and electric responses of near-surface sedimentary rocks on the deformation by earthquake seismic waves in the South of Kamchatka
Authors: Mishchenko Mikhail , Rulenko Oleg , Marapulets Yuriy
Published: November 2021

We continue the investigation of earlier discovered joint acoustic and electric responses of near-surface sedimentary rocks on the deformation by earthquake seismic waves. The appearance and absence of this response in earthquakes with the energy class of more than 11.0, which occurred from June 2017 to May 2021 by the eastern coast of Kamchatka in the latitude band of 51.7-54.0° N, are under consideration. From those earthquakes we selected 52 events, the seismic waves of which had rock acoustic response at Karymshina site, IKIR FEB RAS. Occurrences of joint acoustic and electric responses of rocks and manifestations of their low-frequency and high-frequency acoustic responses were analyzed. Applying the nonparametric correlation Spearman analysis, statistically significant relation between the energy class of the earthquakes under consideration and the distance from hypocenter to the observation site was discovered.
An adaptive finite element DtN method for the elastic wave scattering by biperiodic structures
Authors: Bao Gang , Jiang Xue , Li Peijun , Yuan Xiaokai
Published: November 2021

Consider the scattering of a time-harmonic elastic plane wave by a bi-periodic rigid surface. The displacement of elastic wave motion is modeled by the three-dimensional Navier equation in an unbounded domain above the surface. Based on the Dirichlet-to-Neumann (DtN) operator, which is given as an infinite series, an exact transparent boundary condition is introduced and the scattering problem is formulated equivalently into a boundary value problem in a bounded domain. An a posteriori error estimate based adaptive finite element DtN method is proposed to solve the discrete variational problem where the DtN operator is truncated into a finite number of terms. The a posteriori error estimate takes account of the finite element approximation error and the truncation error of the DtN operator which is shown to decay exponentially with respect to the truncation parameter. Numerical experiments are presented to illustrate the effectiveness of the proposed method.
Impact of Hypothyroidism on Tomography and Biomechanics in Keratoconus – Cross-Sectional and Longitudinal Assessment within the Homburg Keratoconus Center at the Time of
Inclusion and after 1 Year
Authors: Razafimino Sonia , Flockerzi Elias , Zemova Elena , Munteanu Christian , Seitz Berthold
Published: November 2021

Background and Purpose The etiology of keratoconus (KC) is probably multifactorial but remains essentially unknown. Previous scientific observations have suggested that
hypothyroidism might play a role in the development and progression of KC. The purpose of this study was to analyze the tomographic and biomechanical parameters in KC patients with or
without hypothyroidism.

Methods Twenty-eight patients with KC and hypothyroidism (HT group) and fifty-six KC patients without thyroid dysfunction (WHT group) with matching gender and age were analyzed. Mean
age was 40.3 years (range 14 – 57) in the HT group and 40.3 years (range 14 – 57) in the WHT group. Routine ophthalmic examinations consisted of corneal tomography and biomechanical
parameters. We extracted the following KC parameters from the Pentacam (Pentacam HR, Oculus, Wetzlar, Germany): Keratoconus Index (KI), maximum keratometry (Kmax), astigmatism,
and thinnest pachymetry (TP). From the ocular response analyzer (ORA, Reichert Ophthalmic Instruments, Depew, NY, USA), we extracted corneal hysteresis (CH), corneal resistance factor (CRF),
and KC match index (KMI).

Results The comparison of the tomographic and biomechanical values from cross-sectional and longitudinal analyses showed no significant differences between the HT and WHT groups.

Conclusion The severity of KC based on tomographical and biomechanical parameters does not seem to depend on the presence of hypothyroidism.
Initiating a New Era of Cardiovascular Diagnosis and Therapy in Acute Aortic Syndromes: The Mainz–Essen Experience (Part I)—Imaging and Biomarkers
Authors: Bossone Eduardo , Gorla Riccardo , Ranieri Brigida , Russo Valentina , Jakob Heinz , Erbel Raimund
Published: November 2021

Acute aortic syndromes (AAS) encompass a group of life-threatening medical conditions (acute aortic dissection [AAD], intramural hematoma, and penetrating aortic ulcer) with a common pathophysiological pathway. Due to overlapping symptoms and signs with other cardiovascular emergencies, the diagnosis remains challenging resulting in time delays and related increased in-hospital and long-term morbidity and mortality. The Cardiovascular Department of Johannes Gutenberg University in Mainz at West-German Heart Centre in Essen (Germany) first described (in 1984) AAD by transesophageal echocardiography, AAD diagnostic features, and furtherly explored the implementation of “invasive” imaging techniques, namely, intravascular ultrasound and intraluminal phased-array imaging. Furthermore, pioneer studies were undertaken on the biomarker and imaging interplay, namely, D-dimer and F-fluorodeoxyglucose positron emission tomography/computed tomography. We discuss the unique 35-year-long Mainz–Essen experience on the diagnostic and prognostic role of serological and imaging biomarkers in AAS.
Clinical Longevity of Indirect Composite Resin Inlays and Onlays: An Up to 9-Year Prospective Study
Authors: Galiatsatos Aristidis , Galiatsatos Panagiotis , Bergou Dimitra
Published: November 2021

Objective This clinical study evaluated the clinical performance of composite resin inlays and onlays over 9 years.

Materials and Methods Sixty composite resin inlays and onlays were placed in 32 patients, aged 20 to 60 years, by a single operator using the same clinical procedure. The restorations were examined for fracture rate; esthetics; and patient acceptance and marginal integrity, including caries, marginal discoloration, tooth integrity, and surface texture. All restorations were evaluated at the time of placement and 3, 6, and 9 years after placement by using the modified U.S. Public Health Service criteria.

Results At the 3-year follow-up, an Alpha score was given to 88.4% of restorations, while a Bravo score was given to the remaining 11.6%. There was not any failure. At the 6-year follow-up, the success rate of the restorations was 100% without failure. None of the restorations was scored with Delta (D). An Alpha score was given to 60% of the restorations, a Bravo score was assigned to 35%, and a Charlie score was 5% of the restorations. Overall, the success rate of the restorations at 9-year follow-up was 85% and the failure rate was 15%. An Alpha score was given to 15% of the restorations, a Bravo score was given to 50%, a Charlie score was assigned to 20%, and a D score was given to 15% of the restorations.

Conclusion Indirect resin composite inlays and onlays showed acceptable long-term clinical results. The success rate of the restorations at 9-year follow-up was 85% and the failure rate was 15%.
Neuronale Netze: Mit künstlicher Intelligenz der Leukämie auf der Spur
Authors: Reisinger Kathrin
Published: November 2021

Forscher am Nationalen Centrum für Tumorerkrankungen Dresden haben ein Computersystem entwickelt, das mithilfe künstlicher Intelligenz eine akute myeloische Leukämie (AML) präzise erkennen kann. Ärzte und Informatiker des Uniklinikums und der TU Dresden entwickelten künstliche neuronale Netze, die sie mit digitalen Bilddaten von Knochenmarkausstrichen trainierten.
Reproductive Governance in a Fragile and Population-Dense Context: Family Planning Policies, Discourses, and Practices in Burundi
Authors: Schwarz Joëlle , Manirakiza René , Merten Sonja
Published: November 2021

This article describes the reproductive governance deployed in Burundi, which promotes fertility control through uptake of modern contraceptives as a solution to the economic hardship and land pressure of individuals and communities. Using a qualitative approach, we explore how women and couples in rural Burundi set their preferences, choices and practices of family planning, and how they relate with the government discourse. We describe how reproductive practices are complex and modulated by social and material factors and power dynamics. We argue that the current hegemonic discourse—largely supported by external donors—adopts a depoliticised and technocratic approach to family planning that aligns with neoliberal development frameworks, leaving existing power dynamics and resources distribution issues unexamined and unaddressed. By situating reproductive navigation in context, we show how medicalisation of reproduction is not fully enacted, and partly resisted by women and other actors.
Intrinsic electronic noise strength significantly alters a period doubling cascade to chaos
Authors: del Rio Ezequiel , Velarde Manuel G. , Chetverikov Alexander P. , Ebeling Werner , Sergeev Konstantin S.
Published: November 2021

For universality in the approach, it is customary to appropriately rescale problems to a single or a set of dimensionless equations with dimensionless quantities involved or to rescale the experimental setup to a suitable size for the laboratory conditions. Theoretical results and/or experimental findings are supposed to be valid for both the original and the rescaled problems. Here, however, we show in an analog computer model nonlinear system how the experimental results depend on the scale factor. This is because the intrinsic noise in the experimental setup remains constant as it is not affected by the scale factor. The particular case considered here offers a genuine noise-level effect in significantly altering a period-doubling cascade to chaos besides producing an expected truncated cascade. By monitoring with increasing value a significant parameter in the dynamics of the problem when searching for its solution, the system alien to the noise (or better said with a negligible noise level) follows a period-doubling cascade from period one to period two to period four to period eight and, eventually, chaos. However, if the intrinsic noise strength significantly enters the evolution, there appears a parallel sequence of period doublings different from the one found in the previous case.
Global Mittag-Leffler stability and existence of the solution for fractional-order complex-valued NNs with asynchronous time delays
Authors: Li Hui , Kao YongGui
Published: November 2021

This paper is dedicated to exploring the global Mittag-Leffler stability of fractional-order complex-valued (CV) neural networks (NNs) with asynchronous time delays, which generates exponential stability of integer-order (IO) CVNNs. Here, asynchronous time delays mean that there are different time delays in different nodes. Two new inequalities concerning the product of two Mittag-Leffler functions and one novel lemma on a fractional derivative of the product of two functions are given with a rigorous theoretical proof. By utilizing three norms, several novel conditions are concluded to guarantee the global Mittag-Leffler stability and the existence and uniqueness of an equilibrium point. Considering the symbols of the matrix elements, the properties of an M-matrix are extended to the general cases, which introduces the excitatory and inhibitory impacts on neurons. Compared with IOCVNNs, exponential stability is the special case of our results, which means that our model and results are general. At last, two numerical experiments are carried out to explain the theoretical analysis.
Ultrafast optical-field-induced photoelectron emission in a vacuum nanoscale gap: An exact analytical formulation
Authors: Luo Yi , Zhang Peng
Published: November 2021

By exactly solving the one-dimensional time-dependent Schrödinger equation, we construct an analytical solution for nonlinear photoelectron emission in a nanoscale metal–vacuum–metal junction driven by a single-frequency laser field, where the impact of image and space charges is neglected. Based on the analytical formulation, we examine the photoelectron energy spectra and emission current under various laser fields and vacuum gap distances. Our calculation shows the transition from direct tunneling to multiphoton induced electron emission as gap distance increases. In the multiphoton regime, the photoemission current density oscillatorily varies with the gap distance, due to the interference of electron waves inside the gap. Our model reveals the energy redistribution of photoelectrons across the two interfaces between the gap and the metals. Additionally, we find that decreasing the gap distance (before entering the direct tunneling regime) tends to extend the multiphoton regime to higher laser intensity. This work provides clear insights into the underlying photoemission mechanisms and spatiotemporal electron dynamics of ultrafast electron transport in nanogaps and may guide the future design of advanced ultrafast nanodevices, such as photoelectron emitters, photodetectors, and quantum plasmonic nanoantennas.
Sub-50 cm/s surface recombination velocity in InGaAsP/InP ridges
Authors: Andrade Nicolas M. , Hooten Sean , Kim Yunjo , Kim Jeehwan , Yablonovitch Eli , Wu Ming C.
Published: November 2021

The III–V InP/InGaAsP/InGaAs material family is important for photonic devices due to its optical emission and absorption in the 1.55 and 1.3 μm telecommunication bands for optical interconnects. However, InGaAsP/InGaAs generally suffer from relatively high surface recombination velocity—compared to Si [Das et al., in 2020 47th IEEE Photovoltaic Specialists Conference (PVSC) (IEEE, Calgary, AB, 2020), pp. 1167–1170] and InP [Joyce et al., Nano Lett. 12, 5325–5330 (2012)], which reduces the efficiency and can increase the noise in nanophotonic devices. Here, we demonstrate an efficient method to passivate the surface using a combination of sulfur-saturated ammonium sulfide and atomic layer deposition. After annealing, the surface passivation led to a surface recombination velocity as low as 45 cm/s, corresponding to a >180× increase in the photoluminesence of a nanoscale light-emitting device with 200 nm width.
Bifurcations in rotating spherical shell convection under the influence of differential rotation
Authors: Feudel Fred , Feudel Ulrike
Published: November 2021

The bifurcations of thermal convection in a rotating spherical shell heated from the inner sphere and driven by the buoyancy of a central gravity field are studied numerically. This model of spherical Rayleigh–Bénard convection describes large-scale convection in planets and in the outer zones of celestial bodies. In this work, the influence of an additionally imposed differential rotation of the inner sphere with respect to the outer one on the heat transfer and, more generally, on the whole bifurcation structure is investigated. In addition to numerical simulations, path-following techniques are applied in order to compute both stable and unstable solution branches. The dynamics and the heat transfer are essentially determined by a global bifurcation, which we have identified as a homoclinic bifurcation that consists of a collision of a stable modulated rotating with an unstable rotating wave.
Osmotic pressure and swelling behavior of ionic microcapsules
Authors: Alziyadi Mohammed O. , Denton Alan R.
Published: November 2021

Ionic microcapsules are hollow shells of hydrogel, typically 10–1000 nm in radius, composed of cross-linked polymer networks that become charged and swollen in a good solvent. The ability of microcapsules to swell/deswell in response to changes in external stimuli (e.g., temperature, pH, and ionic strength) suits them to applications, such as drug delivery, biosensing, and catalysis. The equilibrium swelling behavior of ionic microcapsules is determined by a balance of electrostatic and elastic forces. The electrostatic component of the osmotic pressure of a microcapsule—the difference in the pressure between the inside and outside of the particle—plays a vital role in determining the swelling behavior. Within the spherical cell model, we derive exact expressions for the radial pressure profile and for the electrostatic and gel components of the osmotic pressure of a microcapsule, which we compute via Poisson–Boltzmann theory and molecular dynamics simulation. For the gel component, we use the Flory–Rehner theory of polymer networks. By combining the electrostatic and gel components of the osmotic pressure, we compute the equilibrium size of ionic microcapsules as a function of particle concentration, shell thickness, and valence. We predict concentration-driven deswelling at relatively low concentrations at which steric interactions between particles are weak and demonstrate that this response can be attributed to crowding-induced redistribution of counterions. Our approach may help to guide the design and applications of smart stimuli-responsive colloidal particles.
Wave-packet behaviors of the defocusing nonlinear Schrödinger equation based on the modified physics-informed neural networks
Authors: Zhang Sheng , Lan Peng , Su Jing-Jing
Published: November 2021

Investigated in this paper is the defocusing nonlinear Schrödinger (NLS) equation, which is used for describing the wave-packet dynamics in certain weakly nonlinear media. With the physics-informed neural networks (PINNs), we modify the corresponding loss function in the existing literature and obtain two types of dark solitons, type-I and type-II solitons. It is demonstrated that the modified loss function presents higher-precision wave-packet behaviors based on fewer initial and boundary data. Taking type-I solitons into consideration, we find that when only a small fraction of initial and boundary data are given, the prediction accuracy of the wave packets will be increased one or two orders of magnitude at least if the modification term of the loss function is introduced. Furthermore, for the inverse problem, the modified loss function provides a better estimate of the nonlinear coefficient of the NLS equation based on fewer observed data of the wave packets. For type-II solitons, we compare the required data and predicted results of the PINNs with those of the conventional time-splitting finite difference (TSFD) method and reveal that achieving the same precision of the wave-packet behavior, the PINNs with the modified loss functions require only one tenth of the amount of the initial and boundary data of the TSFD method. Besides, both unmodified and modified loss functions are exploited for predicting the behaviors of Gaussian wave packets, and it is observed that the predicted result of the modified loss function agrees with the high-precision solution of the time-splitting Fourier pseudospectral method, whereas the unmodified loss function fails.
In situ synchrotron x-ray diffraction studies monitoring mechanochemical reactions of hard materials: Challenges and limitations
Authors: Rathmann Tobias , Petersen Hilke , Reichle Steffen , Schmidt Wolfgang , Amrute Amol P. , Etter Martin , Weidenthaler Claudia
Published: November 2021

In situ monitoring of mechanochemical reactions of soft matter is feasible by synchrotron diffraction experiments. However, so far, reactions of hard materials in existing polymer milling vessels failed due to insufficient energy input. In this study, we present the development of a suitable setup for in situ diffraction experiments at a synchrotron facility. The mechanochemical transformation of boehmite, γ-AlOOH, to corundum, α-Al2O3, was chosen as a model system. The modifications of the mill’s clamping system and the vessels themselves were investigated separately. Starting from a commercially available Retsch MM 400 shaker mill, the influence of the geometrical adaptation of the setup on the milling process was investigated. Simply extending the specimen holder proved to be not sufficient because changes in mechanical forces need to be accounted for in the construction of optimized extensions. Milling vessels that are suitable for diffraction experiments and also guarantee the required energy input as well as mechanical stability were developed. The vessels consist of a steel body and modular polymer/steel rings as x-ray transparent windows. In addition, the vessels are equipped with a gas inlet and outlet system that is connectable to a gas analytics setup. Based on the respective modifications, the transformation of boehmite to corundum could be observed in an optimized setup.
Computational optimal transport for molecular spectra: The fully discrete case
Authors: Seifert Nathan A. , Prozument Kirill , Davis Michael J.
Published: November 2021

The use of computational optimal transport is investigated as a tool for comparing two molecular spectra. Unlike other techniques for comparing molecular spectra in a pattern-recognition framework, transport distances simultaneously encode information about line positions and intensities. In addition, it is shown that transport distances are a useful alternative to Euclidean distances as Euclidean distances are based on line-by-line comparisons, while transport distances reflect broader features of molecular spectra and adequately compare spectra with different resolutions. This paper includes a tutorial on the use of optimal transport and investigates several well-chosen examples to illustrate the utility of computational optimal transport for comparing molecular spectra.
Electronic spectra of positively charged carbon clusters—C2n+ (n = 6–14)
Authors: Buntine Jack T. , Cotter Mariah I. , Jacovella Ugo , Liu Chang , Watkins Patrick , Carrascosa Eduardo , Bull James N. , Weston Luke , Muller Giel , Scholz Michael S. , Bieske Evan J.
Published: November 2021

Electronic spectra are measured for mass-selected C2n+(n = 6–14) clusters over the visible and near-infrared spectral range through resonance enhanced photodissociation of clusters tagged with N2 molecules in a cryogenic ion trap. The carbon cluster cations are generated through laser ablation of a graphite disk and can be selected according to their collision cross section with He buffer gas and their mass prior to being trapped and spectroscopically probed. The data suggest that the C2n+(n = 6–14) clusters have monocyclic structures with bicyclic structures becoming more prevalent for C22+ and larger clusters. The C2n+ electronic spectra are dominated by an origin transition that shifts linearly to a longer wavelength with the number of carbon atoms and associated progressions involving excitation of ring deformation vibrational modes. Bands for C12+, C16+, C20+, C24+, and C28+ are relatively broad, possibly due to rapid non-radiative decay from the excited state, whereas bands for C14+, C18+, C22+, and C26+ are narrower, consistent with slower non-radiative deactivation.
Integration of high permittivity BaTiO3 with AlGaN/GaN for near-theoretical breakdown field kV-class transistors
Authors: Rahman Mohammad Wahidur , Kalarickal Nidhin Kurian , Lee Hyunsoo , Razzak Towhidur , Rajan Siddharth
Published: November 2021

In this Letter, we discuss AlGaN/GaN HEMTs integrated with high permittivity BaTiO3 dielectric to enable enhanced breakdown characteristics. We show that using high permittivity BaTiO3 dielectric layers in the gate and drain access regions prevents premature gate breakdown, leading to average breakdown fields exceeding 3 MV/cm at a gate-to-drain spacing of 4 μm. The higher breakdown fields enable a high power figure of merit above 2.4 GW/cm2 in devices with a gate-to-drain spacing of 6 μm. This work demonstrates that electrostatic engineering using high-permittivity dielectrics can enable AlGaN/GaN HEMTs in approaching the material breakdown field limits.
Production of ultracold CaCCH and SrCCH molecules by direct laser cooling: A theoretical study based on accurate ab initio calculations
Authors: Xia Wensha , Ma Haitao , Bian Wensheng
Published: November 2021

Laser cooling of polyatomic molecules to the ultracold regime may enable some new science and technology applications; however, the related study is still at its very early stage. Here, by means of accurate ab initio and dynamical calculations, we identify two new candidate tetratomic molecules that are suitable for laser cooling and demonstrate the feasibility and advantage of two laser cooling schemes that are able to produce ultracold CaCCH and SrCCH molecules. The internally contracted multiconfiguration reference configuration interaction method is applied, and excellent agreement is achieved between the computed and experimental spectroscopic data. We find that the X2Σ1/2+→A2Π1/2 transitions for both candidates feature diagonal Franck–Condon factors, short radiative lifetimes, and no interference from intermediate electronic states. In addition, the crossings with higher electronic states do not interfere. We further construct feasible laser cooling schemes for CaCCH and SrCCH, each of which allows scattering 104 photons for direct laser cooling. The estimated Doppler temperatures for both CaCCH and SrCCH are on the order of μK.
Significant phonon anharmonicity drives phase transitions in CsPbI3
Authors: Gu Hong-Yang , Yin Wan-Jian , Gong Xin-Gao
Published: November 2021

Due to its high chemical stability and high power conversion efficiency as a solar cell absorber, the inorganic halide perovskite, CsPbI3, is considered one of the most promising competitors to its hybrid organic-inorganic counterpart, CH3NH3PbI3. However, the phase transition from the photoactive black phase to the inactive yellow phase is a remarkable limitation that harms long-term phase stability. In particular, the phase transitions follow different pathways as the temperature increases and/or decreases, a phenomenon that is anomalous and remains poorly understood. In this study, we systematically calculated the temperature-dependent free energy of CsPbI3 in different crystal phases (α, β, γ, δ) by considering the phonon contribution to the Gibbs free energy. It is found that the free energy results from calculations that include harmonic phonons cannot reproduce experimental observations. Alternatively, we utilized the renormalized phonon quasiparticle approach to derive the free energies of different CsPbI3 phases at finite temperatures. Based on these calculated free energies, whose derivations included the anharmonic effect, we observed phase-transition processes consistent with experimental results. The analysis of the temperature effect on the phonon frequencies further demonstrated that anharmonic effects in the CsPbI3 had a significant influence on its phase transitions.
Application of circular economy principles to pastoral farming: development of an assessment framework
Authors: Burggraaf V. T. , Mazzetto A. M. , Romera A. J. , Mercer G. J. K. , Ledgard S. F.
Published: November 2021

Context Circular economy principles are being adopted to design out waste, use resources more efficiently and maintain ecosystem health. Aims This study developed a framework to assess the ‘circularity’ of pastoral farms, using a New Zealand dairy farm as a case study. Methods Key resource inputs and environmental impacts to assess for the farming system were determined. Nitrogen and phosphorus flows were assessed using the OVERSEER® model, to then determine their circularity on the basis of the material circularity indicator. Life-cycle assessment was used to determine the carbon footprint and fossil fuel depletion associated with the farm. Single-use plastic disposal was calculated on the basis of farm purchases and end-points of packaging. Key results MCI circularity scores were 0.46 for nitrogen, 0.48 for phosphorus and total circularity 0.46, which could be improved by focusing on reducing the high rates of mineral fertiliser use and large losses of nitrogen to water and the atmosphere. Although the farm’s cradle-to-farm-gate fossil fuel resource depletion footprint (1.16 MJ/kg fat- and protein-corrected milk) was low compared with other New Zealand and European dairy farms, its carbon footprint of 0.85 kg carbon dioxide-equivalent/kg fat and protein corrected milk was high for New Zealand, with enteric methane emissions and inputs of supplementary feeds being the major sources. Plastic waste was a minor source of waste compared with nutrients, but the key sources were identified. Conclusions and implications This framework could be used and adapted to assess the circularity of nutrients in pastoral farming systems and help identify key areas to reduce the depletion of critical resources and negative environmental impacts. Further development and testing are required for a range of farming systems.