bluuebunny/crossref_metadata_2025 huggingface dataset:
Soluble (pro)renin receptor induces endothelial dysfunction and hypertension in mice with diet-induced obesity via activation of angiotensin II type 1 receptor
Authors: Fu Ziwei , Wang Fei , Liu Xiyang , Hu Jiajia , Su Jiahui , Lu Xiaohan , Lu Aihua , Cho Jae Min , Symons J. David , Zou Chang-Jiang , Yang Tianxin
Published: February 2021

Until now, renin–angiotensin system (RAS) hyperactivity was largely thought to result from angiotensin II (Ang II)-dependent stimulation of the Ang II type 1 receptor (AT1R). Here we assessed the role of soluble (pro)renin receptor (sPRR), a product of site-1 protease-mediated cleavage of (pro)renin receptor (PRR), as a possible ligand of the AT1R in mediating: (i) endothelial cell dysfunction in vitro and (ii) arterial dysfunction in mice with diet-induced obesity. Primary human umbilical vein endothelial cells (HUVECs) treated with a recombinant histidine-tagged sPRR (sPRR-His) exhibited IκBα degradation concurrent with NF-κB p65 activation. These responses were secondary to sPRR-His evoked elevations in Nox4-derived H2O2 production that resulted in inflammation, apoptosis and reduced NO production. Each of these sPRR-His-evoked responses was attenuated by AT1R inhibition using Losartan (Los) but not ACE inhibition using captopril (Cap). Further mechanistic exploration revealed that sPRR-His activated AT1R downstream Gq signaling pathway. Immunoprecipitation coupled with autoradiography experiments and radioactive ligand competitive binding assays indicate sPRR directly interacts with AT1R via Lysine199 and Asparagine295. Important translational relevance was provided by findings from obese C57/BL6 mice that sPRR-His evoked endothelial dysfunction was sensitive to Los. Besides, sPRR-His elevated blood pressure in obese C57/BL6 mice, an effect that was reversed by concurrent treatment with Los but not Cap. Collectively, we provide solid evidence that the AT1R mediates the functions of sPRR during obesity-related hypertension. Inhibiting sPRR signaling should be considered further as a potential therapeutic intervention in the treatment and prevention of cardiovascular disorders involving elevated blood pressure.
Time‐phased electricity package design for electricity retailers considering bounded rationality of consumers
Authors: Zhang Zhi , Lin Zhenzhi , Wen Fushuan , Yang Li , Xue Yusheng
Published: February 2021

The ever‐increasing competition in electricity retail markets has become one of the pivotal causes for electricity retailers to provide attractive packages to consumers for enhancing their market shares. Based on the current user‐side time‐of‐use electricity price mechanism in China, a bi‐level optimization model for designing a time‐phased and quantity‐incentive electricity package is proposed for electricity retailers considering bounded rationality of consumers. In the upper‐level model, the optimization objective is to maximize the electricity purchase and sale revenue of a specified retailer. In the lower‐level model, consumers are modelled as bounded rational decision‐makers whose objective is to purchase the electricity package with the highest value, considering the value of the excess electricity of the package. In addition, consumer psychology theory is introduced to describe the bounded rational responses of consumers to electricity packages. Simulations based on data of residential consumers in a city of China illustrate that by properly determining package quotas in different time periods, electricity retailers can guide consumers to change consumption time and volume, and hence, increase their revenues by increasing trading volume or reducing electricity procurement costs in forward bilateral transactions and spot markets.
Integrated control of torque and emission of a diesel engine based on LPV‐MPC
Authors: Sun Mengge , Hu Yunfeng , Xu Fang , Gao Jinwu , Chen Hong
Published: February 2021

This study presents an integrated control scheme of a diesel engine which aims to ensure quick torque response while limiting the average NOx emission below the certain specification. To start with, the sensitivity analysis is performed to recognize the key factors determined to balance emission, torque and fuel consumption. Considering the strong nonlinearity of the diesel engine, a multi‐input multi‐output (MIMO) linear parameter varying (LPV) model is developed. Unlike the conventional state‐depended LPV modelling process, the proposed LPV model is built based on a kernel function with a novel form of state‐free predictive equation so that the system outputs are directly computed. The control objective of coordinating torque tracking and emission reduction is then accomplished by designing a model predictive controller that regulates the fuel injection quantity, fuel injection angle, exhaust gas recirculation (EGR) rate and the opening degree of variable geometry turbine (VGT) valve. Finally, the developed LPV model and the MPC controller are testified with a high‐fidelity commercial diesel engine model. The results show that the LPV‐MPC controller is able to satisfy the NOx emission specification and the engine torque tracks the desired reference fast in transients, while the control variables are suitably actuated within the actuator constraints.
Image compact‐resolution and reconstruction using reversible network
Authors: Yang Jieming , Ge Hongwei , Yang Jinlong , Tong Yubing
Published: February 2021

The dual problem of image super‐resolution (SR), which is referred to as compact‐resolution (CR), and the corresponding image reconstruction are studied. These two problems have been studied independently by the researchers. In this study, a novel model for image CR and the corresponding reconstruction using the reversible network has been proposed. The reversible network has two properties, the first property, lossless information forwarding, which makes the compact‐resolved image retain more information from the original HR image. The second property, bidirectional mapping, by which the forward and reverse propagation of a reversible network can be utilised to implement image CR and reconstruction, respectively, i.e. using the reverse process of image CR to guide the reconstruction. In addition, the utilisation of a reversible network may reduce the size of the model. The superiority of the proposed model was demonstrated by comparing its performance with the state‐of‐the‐art methods on four well‐known benchmark datasets.
Low‐complexity block tree image coder for visual sensor networks
Authors: Lone Mohd Rafi , Khan Ekram
Published: February 2021

The wavelet block tree coding (WBTC) algorithm is an efficient wavelet‐based image coder. In this coder, multiple spatial orientation trees are combined together to make a single block tree. It uses three ordered lists to keep track of significant/insignificant coefficients and sets while coding, which increases its memory requirement as well as computational complexity. Also, it uses memory inefficient conventional discrete wavelet transform (DWT) to compute the transformed coefficients. In this study, a Low‐Complexity Block Tree Coding (LCBTC) algorithm that uses two state‐tables and two very small lists, is proposed. Similar to WBTC, it also uses sorting and refinement passes in each bit‐plane. However, it encodes the coefficients in block‐tree manner using depth‐first search approach to reduce the computational complexity. It uses DWT coefficients obtained from modified fractional wavelet filter (MFrWF) rather than conventional DWT, which further reduces the overall memory and complexity of the image coder. The simulation results show that the memory requirement and computational complexity of LCBTC is much less than WBTC and other state‐of‐the‐art coding algorithms. These features make the image coder a better candidate for compression in memory constrained and real‐time visual sensor networks.
Automated classification system for drowsiness detection using convolutional neural network and electroencephalogram
Authors: Balam Venkata Phanikrishna , Sameer Venkata Udaya , Chinara Suchismitha
Published: February 2021

Detecting drowsiness in drivers while driving is extremely important to avoid possible accidents and reduce the fatality rate due to drivers sleeping at the wheel. A real‐time alert generation when the driver might possibly go into sleepy state is essential to safeguard any unwarranted incidents. Wearable sensors to monitor vehicle movement and camera‐based systems to monitor driver behaviour are commonly used to detect driver drowsiness. Due to the fact that electroencephalogram (EEG) signals have the ability to monitor the mood of humans and are easily obtainable, many different EEG‐based drowsiness detection systems have been proposed to date. In this study, a novel deep learning architecture based on a convolutional neural network (CNN) is proposed for automated drowsiness detection using a single‐channel EEG signal. To improve the generalization performance of the proposed method, subject‐wise, cross‐subject‐wise, and combined‐subjects‐wise validations have been employed. The whole of the work is carried over pre‐recorded sleep state EEG data obtained from benchmarked dataset. The experimental results show a superior detection capability compared to the existing state–of–the–art drowsiness detection methods using single‐channel EEG signals.
An underlying universal pattern in galaxy halo magnetic fields
Authors: Myserlis Ioannis , Contopoulos Ioannis
Published: February 2021

Magnetic fields in galaxy halos are in general very difficult to observe. Most recently, the Continuum HAlos in Nearby Galaxies – an EVLA Survey (CHANG-ES) Collaboration investigated the radio halos of 35 nearby edge-on spiral galaxies in detail and detected large-scale magnetic fields in 16 of them. We used the CHANG-ES radio polarization data to create rotation measure maps for all galaxies in the sample and stack them with the aim of amplifying any underlying universal toroidal magnetic field pattern in the halo above and below the disk of the galaxy. We discovered a large-scale magnetic field in the central region of the stacked galaxy profile, which is attributable to an axial electric current that universally outflows from the center, both above and below the plane of the disk. A similar symmetry-breaking has also been observed in astrophysical jets, but never before in galaxy halos. This is an indication that galaxy halo magnetic fields are probably not generated by pure magnetohydrodynamic processes in the central regions of galaxies. One such promising physical mechanism is the Cosmic Battery operating in the innermost accretion disk around the central supermassive black hole. We anticipate that our discovery will stimulate a more general discussion on the origin of astrophysical magnetic fields.
New low-mass members of Chamaeleon I and ϵ Cha
Authors: Kubiak K. , Mužić K. , Sousa I. , Almendros-Abad V. , Köhler R. , Scholz A.
Published: February 2021

Aims. The goal of this paper is to increase the membership list of the Chamaeleon star-forming region and the ϵ Cha moving group, in particular for low-mass stars and substellar objects. We extended the search region significantly beyond the dark clouds.

Methods. Our sample has been selected based on proper motions and colours obtained from Gaia and 2MASS. We present and discuss the optical spectroscopic follow-up of 18 low-mass stellar objects in Cha I and ϵ Cha. We characterize the properties of objects by deriving their physical parameters from spectroscopy and photometry.

Results. We add three more low-mass members to the list of Cha I and increase the census of known ϵ Cha members by more than 40%, thereby spectroscopically confirming 13 new members and relying on X-ray emission as youth indicator for 2 more. In most cases the best-fitting spectral template is from objects in the TW Hya association, indicating that ϵ Cha has a similar age. The first estimate of the slope of the initial mass function in ϵ Cha down to the substellar regime is consistent with that of other young clusters. We estimate our initial mass function (IMF) to be complete down to ≈0.03 M⊙. The IMF can be represented by two power laws: for M < 0.5 M⊙ α = 0.42 ± 0.11 and for M > 0.5 M⊙ α = 1.44 ± 0.12.

Conclusions. We find similarities between ϵ Cha and the southernmost part of Lower Centaurus Crux (LCC A0), which lie at similar distances and share the same proper motions. This suggests that ϵ Cha and LCC A0 may have been born during the same star formation event
Exploring the radial evolution of interplanetary coronal mass ejections using EUHFORIA
Authors: Scolini C. , Dasso S. , Rodriguez L. , Zhukov A. N. , Poedts S.
Published: February 2021

Context. Coronal mass ejections (CMEs) are large-scale eruptions coming from the Sun and transiting into interplanetary space. While it is widely known that they are major drivers of space weather, further knowledge of CME properties in the inner heliosphere is limited by the scarcity of observations at heliocentric distances other than 1 au. In addition, most CMEs are observed in situ by a single spacecraft and in-depth studies require numerical models to complement the few available observations.

Aims. We aim to assess the ability of the linear force-free spheromak CME model of the EUropean Heliospheric FORecasting Information Asset (EUHFORIA) to describe the radial evolution of interplanetary CMEs in order to yield new contexts for observational studies.

Methods. We modelled one well-studied CME with EUHFORIA, investigating its radial evolution by placing virtual spacecraft along the Sun–Earth line in the simulation domain. To directly compare observational and modelling results, we characterised the interplanetary CME signatures between 0.2 and 1.9 au from modelled time series, exploiting techniques that are traditionally employed to analyse real in situ data.

Results. Our results show that the modelled radial evolution of the mean solar wind and CME values is consistent with the observational and theoretical expectations. The CME expands as a consequence of the decaying pressure in the surrounding solar wind: the expansion is rapid within 0.4 au and moderate at larger distances. The early rapid expansion was not sufficient to explain the overestimated CME radial size in our simulation, suggesting this is an intrinsic limitation of the spheromak geometry applied in this case. The magnetic field profile indicates a relaxation on the part of the CME structure during propagation, while CME ageing is most probably not a substantial source of magnetic asymmetry beyond 0.4 au. Finally, we report a CME wake that is significantly shorter than what has been suggested by observations.

Conclusions. Overall, EUHFORIA provides a consistent description of the radial evolution of solar wind and CMEs, at least close to their centres. Nevertheless, improvements are required to better reproduce the CME radial extension.
Inactivation of Herpes Simplex Virus by Photosensitizing Anthraquinones Isolated from Heterophyllaea pustulata
Authors: Mugas M. Laura , Marioni Juliana , Martinez Florencia , Aguilar Juan J. , Cabrera José L. , Contigiani Marta S. , Konigheim Brenda S. , Núñez-Montoya Susana C.
Published: February 2021

Heterophyllaea pustulata is a phototoxic plant from Argentina. Aerial parts extracts, high in photosensitizing anthraquinones, have shown in vitro antiviral activity. The purpose of this study was to study the antiherpetic activity of the main purified anthraquinones, even evaluating their competence as photodynamic sensitizers to photo-stimulate the antiviral effect. In vitro antiviral activity against Herpes Simplex virus type I and the photo-inactivation of viral particle were studied by the Neutral Red uptake test and observation of the cytopathic effect. Rubiadin 1-methyl ether and 5,5′-bisoranjidiol produced a significant effect (≥ 80% inhibition) with minimal damage to host cells (subtoxic concentration). Anthraquinones with poor antiherpetic activity at its maximum noncytotoxic concentration showed an important photo-stimulated effect, such is the case of soranjidiol and 5,5′-bisoranjidiol (28.0 ± 6.3 vs. 81.8 ± 2.1% and 15.5 ± 0.3
vs. 89.8 ± 1.7%, respectively). The study also proved the decrease of viral particles, necessary to reduce infection. Therefore, photosensitizing anthraquinones from natural resources could be proposed to develop new treatments for localized viral lesions with antimicrobial photodynamic therapy.
Poststationäre Weiterbehandlung von Patienten mit ICD-Diagnosen F3 und F4 in Psychiatrie und Psychosomatik (PfAD-Studie)
Authors: Bichescu-Burian Dana , Jaeger Susanne , Steinert Tilman , Uhlmann Carmen , Flammer Erich
Published: February 2021

Ziel Untersuchung poststationärer Behandlungswege und ihrer Prädiktoren.

Methode In einer prospektiven naturalistischen Studie wurden 320 Erwachsene, die in 4 stationären Settings behandelt wurden, bei Aufnahme, Entlassung und zu 2 Nachbeobachtungszeitpunkten untersucht. Mit standardisierten Instrumenten wurden soziodemografische und klinische Daten sowie Wege im Versorgungssystem im Halbjahr vor und im Jahr nach der Indexbehandlung erhoben. Deskriptive Analysen und logistische Regressionsmodelle wurden angewandt.

Ergebnisse Stationäre Behandlungen nach Entlassung aus der Indexbehandlung waren mehrheitlich geplante Weiterbehandlungen. Fast alle Patienten wurden ambulant nachbehandelt. Hauptprädiktoren für stationäre Behandlung nach Indexbehandlung und für ambulante Psychotherapie waren das Index-Setting (Psychiatrie/Psychosomatik) sowie vorbestehende und geplante Behandlungen.

Schlussfolgerung Die Behandlungswege in Psychiatrie und Psychosomatik entsprechen der vorgegebenen Indikation, verlaufen aber meist getrennt voneinander und zeigen wenig Überschneidung.
1-Year Evaluation of OT Bridge Abutments for Immediately Loaded Maxillary Fixed Restorations: A Multicenter Study
Authors: Acampora Rosario , Montanari Marco , Scrascia Roberto , Ferrari Emiliano , Pasi Massimo , Cervino Gabriele , Meloni Silvio Mario , Lumbau Aurea Immacolata , Xhanari Erta , Koshovari Alba , Tallarico Marco
Published: February 2021

Objective  Preliminary data on survival and success rates of immediately loaded, maxillary, screw-retained, implant-supported, fixed restorations delivered on narrow and low-profile OT Equator abutments (OT Bridge, Rhein’83) were evaluated.

Materials and Methods This retrospective study evaluated data collected from patients rehabilitated with OT Bridge prosthetic concept between November 2017 and February 2019 in six different centers. Outcome measures were implant and prosthetic survival rates, biological and technical complications, marginal bone loss (MBL), oral health impact profile (OHIP), bleeding on probing, and plaque index.

Results A total of 76 implants were inserted in 14 patients. Patients were followed for a mean period of 15.8 months (range = 12–24). All the patients receive OT Equator (Rhein'83) as intermediate abutments. One year after loading, one implant failed (1.3%). None of the prosthesis failed. One prosthetic complication was experienced in one patient. Three out of 76 implants were connected to the prosthetic framework using only the Seeger system, without screw. Difference in OHIP values was statistically significant (71.9 ± 8.5; p = 0.000). One year after loading, MBL was 0.21 ± 0.11 mm and p-value was 0.000. One year after loading, 8.7% of the examined implant sites present positive bleeding on probing, while 6.4% of the implant sites presented plaque.

Conclusion The OT Equator abutments (Rhein'83) showed successful results when used to support maxillary fixed dental prosthesis delivered on four to six implants. High implant and prosthetic survival rates, very low complications, high patient satisfaction, and good biological parameters, including only 0.2 mm of bone remodeling were experienced one year after function. Further studies are needed to confirm these preliminary results.
Evaluation and Medical Management of Uncomplicated Diverticulitis
Authors: Langenfeld Sean J.
Published: February 2021

Uncomplicated diverticulitis is common, and its evaluation and treatment have evolved over time. Most patients present in a nontoxic manner with localized pain, leukocytosis, and reliable findings on computed tomography (CT). Healthy and stable patients are typically treated in the outpatient setting with very high rates of success. Recently, the necessity of antibiotic therapy has come into question, and several alternative agents have emerged, with the jury still out on their relative roles in diverticular disease. Currently, colonoscopy is still recommended after the resolution of an index episode of uncomplicated diverticulitis, and recurrence rates remain low. Several diet and lifestyle modifications have been shown to impact the rates of diverticulitis recurrence.
Management of Traumatic Cervical Spondyloptosis
Authors: Rai Hitesh Inder Singh , Garg Kanwaljeet , Agrawal Deepak
Published: February 2021

Traumatic cervical spondyloptosis is a 3-column fracture-dislocation resulting in a highly unstable spine requiring urgent reduction, stabilization, and fixation. Since its occurrence is not that common, there are a lot of controversies concerning its management. A holistic approach has been proposed regarding the management of traumatic cervical spondyloptosis.
Endonasal FLI Approach for Rhinoplasty with Modified Cottle Low Strip Septoplasty
Authors: López-Ulloa Fausto , Jasso-Ramírez Elizabeth , Friedman Oren
Published: February 2021

To date, an endonasal approach has not been described that combines different incisions to provide exposure of all of the key anatomical structures, allowing for adequate, comprehensive visualization of the nasal architecture including the complete quadrangular cartilage and its extension with the upper lateral cartilages, including the caudal septal border from the ventral border and anterior nasal spine to the anterior septal angle, the scroll, and internal nasal valve.

The endonasal approach that Fausto Lopez-Infante designed, the FLI technique, combines several basic known endonasal incisions that together allow excellent access and great visualization of the intranasal surgical field, enables extensive septal work, and preserves the natural anatomy of the dorsum as well as the tip support structures.

This technique and approach to nasal surgery are based on an understanding of anatomy, allow standardization of the surgery, and make it reproducible. It is an outstanding option with excellent cosmetic and functional results.
120 Years of Dorsal Preservation in Rhinoplasty
Authors: Ng Chew Lip , D'Souza Alwyn Ray
Published: February 2021

Dorsal preservation techniques in rhinoplasty are experiencing a renaissance in recent years. New techniques and modifications to existing techniques are being described at an intensifying pace. Dorsal preservation, however, is not a new concept and was first described over 120 years ago. It is timely that we conduct a review of the key techniques and concepts of dorsal preservation in rhinoplasty that had been published over the past 120 years, at a moment in which we consider as a revival of this school of thought.
A Prospective Study on the Incidence and Outcome of Cranial Nerve Injuries in Patients with Traumatic Brain Injuries
Authors: Basheer Noufal , Varghese Jenimol Chacko , Kuruvilla Rojan , Alappat Jacob P. , Mathew Jim
Published: February 2021

Background Posttraumatic cranial nerve injuries are not uncommon and can occur by shearing forces, rapid acceleration/deceleration, or injury to the skull base. The incidence of cranial nerve injury in craniocerebral trauma varies between 5 and 23 percent in various literature.

Methodology A prospective study was conducted on the incidence and outcome of cranial nerve injuries (CNI) in 256 consecutive cases of traumatic brain injuries (TBI). Patients over the age of 5 years with a follow-up of 6 months in the period from September 2017 to November 2018 in our institution were sampled.

Results A total of 256 patients were included in our study. The incidence of CNI in TBI patients was 14.8% (38 patients). Facial nerve was the most common cranial nerve to be involved, followed by olfactory nerve and vestibulocochlear nerve. Cranial nerve injury was more common in patients with severe head injury (p < 0.005), younger age group, associated base of skull fractures (p < 0.001), and facial fractures (p < 0.005). Twenty-eight patients (73.7%) had a delayed presentation of CNI (p < 0.001). Of the 73.6% patients who recovered, 16 (42%) patients had partial recovery, while 12 (31%) patients had complete recovery. Younger age group (p < 0.05) and delayed onset of deficit (p < 0.001) were associated with significant better outcome.

Conclusions CNI are a major cause of morbidity in TBI patients. All patients admitted with TBI should be examined meticulously for CNI on follow-up.
Arrow-Shot Injury to Pediatric Spinal Cord
Authors: Singh Vijayveer , Thanvi Sharad
Published: February 2021

Penetrating spinal cord injuries (PSCI) in cervical region are extremely rare in pediatric population. Most injuries in pediatric population are accidental due to gunshot or a stab injury with a sharp or pointed object. Gun shots may result into a severe wound which is usually fatal and may result in death, quadriplegia, or serious long-term disability. Stab injuries are less severe and may result in neurological sequalae. In this paper, an unusual case of pediatric arrow shot partial cervical cord injury is reported which was managed by aggressive neurosurgical management. The arrow lodged in the cervical cord was very near to the vertebral artery leading to parapariesis which recovered well without any complications. Diagnostic imaging at admission included radiographs, computed tomography (CT), and CT angiography of the cervical region. The patient underwent early surgical intervention with removal of foreign body from the cord and subsequent dural suturing.
Approach to Emergent Neurotrauma-related Neurosurgical Procedures in Patients with Hepatic Disease
Authors: Mendoza-Avendaño María , Ramírez-Carvajal Ana , Barreto-Herrera Iván , Muñoz-Báez Karen , Ramos-Villegas Yancarlos , Shrivastava Adesh , Janjua Tariq , Moscote-Salazar Luis Rafael , Agrawal Amit
Published: February 2021

Liver diseases constitute a group of pathologies of extraordinary importance, because of the large number of patients who suffer from these as well as the consequences that they can have on these individuals if they undergo any surgical procedure. Therefore, these patients have greater risk of suffering unfavorable outcomes than a healthy person undergoing emergency neurosurgical procedures (ENP) for neurotrauma. For this reason, there is a need to classify these patients according to their surgical risk based on risk factors secondary to the concurrent hepatic derangements. Among the possible tools that allow us to stage patients with liver disease are the Child–Turcotte–Pugh (CTP) and model for end-stage liver disease (MELD) scales, which have proven utility in effectively predicting the outcomes, including morbidity and mortality in hepatic disease patients who are undergoing surgery. They also help to predict the risk of complications such as intracranial hemorrhage secondary to coagulopathy due to hepatic derangement.
A colossus with feet of clay? Assessing Germany’s prevalence in European Union lawmaking
Authors: Kirpsza Adam
Published: February 2021

The distributive bargaining literature argues that Germany prevails in the European Union due to its superior power resources. This paper tests this expectation empirically by assessing Germany’s success on actual EU legislation with three sources of data: Council voting records (2009–2019), decision outcomes on the most controversial proposals (1999–2009) and the outcomes of the Eurozone reform (2010–2015). The results provide no support for Germany’s prevalence in daily EU lawmaking. This country is found to cast a substantive number of contestations in the Council and attain significantly lower bargaining success than other member states on key EU secondary legislation. The paper suggests that such poor showing stems from a high extremity and intensity of Germany’s preferences. Generally, this study contributes to the scholarly knowledge by refuting the narrative that Germany dictates actual EU legislation and challenging the distributive bargaining argument that states with greater power resources are more successful in the EU.
Attenuation of waves in glasses better understood through computer simulations
Authors: Johnson-Groh Mara
Published: February 2021

Predicting wave attenuation rates in glasses has been shown to be possible by studying sample-to-sample fluctuations of its elastic moduli, rather than its spatial fluctuations.
Delay-induced uncertainty for a paradigmatic glucose–insulin model
Authors: Karamched Bhargav , Hripcsak George , Albers David , Ott William
Published: February 2021

Medical practice in the intensive care unit is based on the assumption that physiological systems such as the human glucose–insulin system are predictable. We demonstrate that delay within the glucose–insulin system can induce sustained temporal chaos, rendering the system unpredictable. Specifically, we exhibit such chaos for the ultradian glucose–insulin model. This well-validated, finite-dimensional model represents feedback delay as a three-stage filter. Using the theory of rank one maps from smooth dynamical systems, we precisely explain the nature of the resulting delay-induced uncertainty (DIU). We develop a framework one may use to diagnose DIU in a general oscillatory dynamical system. For infinite-dimensional delay systems, no analog of the theory of rank one maps exists. Nevertheless, we show that the geometric principles encoded in our DIU framework apply to such systems by exhibiting sustained temporal chaos for a linear shear flow. Our results are potentially broadly applicable because delay is ubiquitous throughout mathematical physiology.
Dynamic economic dispatch problem in hybrid wind based power systems using oppositional based chaotic grasshopper optimization algorithm
Authors: Mandal Barun , Roy Provas Kumar
Published: February 2021

This article introduces a relatively current method named grasshopper optimization algorithm (GOA) for explaining power system based dynamic economic load dispatch (DELD) problem. However, like other optimization approaches, GOA suffers from premature convergence and a slow convergence rate. Thus, to boost the convergence mobility of GOA, oppositional based learning (OBL) is merged with the GOA approach. Moreover, another improvization, namely, chaotic concept, is also integrated with the GOA to improve its solution quality. The suggested oppositional based chaotic grasshopper optimization algorithm (OCGOA) method is applied to handle the DELD problem in the most efficient manner. Among the renewable energies, intermittent wind energy (WE) is the most sustainable one and remains technically and economically advantageous for electrical energy generation. The thermal and wind based power systems are hybridized, so that power generation is distributed among the operating units in an equivalent manner such that overall cost and loss part are optimized until all practical constraints are fulfilled. The production cost of the unpredictable wind generation power is further incorporated in the operational cost by employing a probability density function (PDF) formula. The precision and performance of the suggested GOA and OCGOA approaches are validated on 6-unit and 10-unit DELD systems for conventional and wind based energy systems. The efficacy and performance of the suggested OCGOA is judged by comparing it with conventional GOA and other presently developed meta-heuristic optimization techniques found in the literature.
Birth and destruction of collective oscillations in a network of two populations of coupled type 1 neurons
Authors: Jüttner Benjamin , Henriksen Christian , Martens Erik A.
Published: February 2021

We study the macroscopic dynamics of large networks of excitable type 1 neurons composed of two populations interacting with disparate but symmetric intra- and inter-population coupling strengths. This nonuniform coupling scheme facilitates symmetric equilibria, where both populations display identical firing activity, characterized by either quiescent or spiking behavior, or asymmetric equilibria, where the firing activity of one population exhibits quiescent but the other exhibits spiking behavior. Oscillations in the firing rate are possible if neurons emit pulses with non-zero width but are otherwise quenched. Here, we explore how collective oscillations emerge for two statistically identical neuron populations in the limit of an infinite number of neurons. A detailed analysis reveals how collective oscillations are born and destroyed in various bifurcation scenarios and how they are organized around higher codimension bifurcation points. Since both symmetric and asymmetric equilibria display bistable behavior, a large configuration space with steady and oscillatory behavior is available. Switching between configurations of neural activity is relevant in functional processes such as working memory and the onset of collective oscillations in motor control.
Experimental and calculational investigation of laser-heated additive manufactured foams
Authors: Jones O. S. , Kemp G. E. , Langer S. H. , Winjum B. J. , Berger R. L. , Oakdale J. S. , Belyaev M. A. , Biener J. , Biener M. M. , Mariscal D. A. , Milovich J. L. , Stadermann M. , Sterne P. A. , Wilks S. C.
Published: February 2021

Foam materials are starting to find application in laser-heated Hohlraums used to drive inertial confinement fusion implosions. Foams made using additive manufacturing (AM) techniques are now available and may have advantages over traditional chemical (aerogel) foams. Here, we present new experimental data on laser-heated AM foams. Samples of four different types of printed AM foams were heated using a single 527 nm laser beam at the Jupiter Laser Facility. The laser pulse was ∼180 J square pulse with an FWHM of 1.6 ns and a peak intensity of 3–4 × 1014 W/cm2. The foam densities ranged from 12 to 93 mg/cc (all supercritical for 527 nm light). We measured the backscattered light (power and spectrum), the transmitted light, side-on x-ray images, and the Ti K-shell emission that was used to infer the time-integrated temperature. The fraction of backscattered light was 6%–15% of the input laser energy. The pure carbon foam sample had less backscatter than a C8H9O3 foam of similar density, which was consistent with multi-fluid calculations that predicted less ion heating for the C8H9O3 foam. The level of backscatter and the thermal front speeds for the AM foams were similar to values measured for stochastic (aerogel) foams under similar conditions.
Oscillatory flow around a vertical wall-mounted cylinder: Flow pattern details
Authors: Jang H. K. , Ozdemir C. E. , Liang J.-H. , Tyagi M.
Published: February 2021

The interaction between surface gravity waves and a vertical wall-mounted rigid cylindrical structure such as a pier or vegetation involves various interdependent physical phenomena including the scouring process and the vertical mixing and horizontal dispersion of materials. As a step toward understanding this interaction, detailed flow fields of sinusoidal oscillatory flow passing a vertical wall-mounted cylinder are numerically investigated for three different wave conditions. With a moderately wide range of the Keulegan–Carpenter number from 6 to 20, numerical simulations are systematically performed, and the data are extensively investigated to determine the dynamic characteristics of the oscillatory flow past a wall-mounted cylinder. In this study, three-dimensional unsteady incompressible Navier–Stokes equations are solved using the open-source software, OpenFOAM®. Grid-convergence tests are conducted, and the undisturbed oscillating Stokes boundary-layer determined by numerical simulations is validated by a good agreement with the analytical solution. Flow details in the form of profiles, streamlines, and contours of calculated turbulence fields are presented. Coherent structure dynamics is illustrated using iso-surfaces of the Q-criterion. The synthesis of various flow variables presents a mechanistic view of the bed shear and processes responsible for scour near the cylinder-wall junction.
Generalized non-ideal treatment and growth rates analysis of drift waves instabilities in a collisions-free magnetized dusty plasma
Authors: Puerta J. , Martin P. , Maass F. , Puerta J. B. , Brito J.
Published: February 2021

Dust acoustic wave propagation in weak magnetized homogeneous dusty plasmas has been extensively and successfully studied by different authors. Here, it is analyzed the behavior of electrostatic drift waves of very low frequency, appearing as due to the motion of plasma particles across the static magnetic field and the inhomogeneity introduced by the distribution of the particles in the dusty plasma generating the well-known diamagnetic effect. To study this situation, the kinetic Vlasov model in plasmas will be used. However, these models tend to behave unstably driven by the quasi-equilibrium of the diamagnetic current arising by the heavier species of dusty plasma particles. While other authors have used a standard state equation, such as the Van der Waals one, here, a more accurate model has been chosen as the equation of Ree and Hoover, a state equation that can be considered as a new form of the state equation. Together with the multipole approximation of the dispersion function, Z53 [P. Martin et al., J. Math. Phys. 21, 280–283 (1980)] allows a new derivation to obtain the simplest form of the dispersion relation in the form of a polynomial with complex coefficients. This mathematical approach was realized successfully and allowed straightforward calculus of the growth rate due to the drift unstable mode. This problem has been extensively analyzed in this work, including the non-ideal effect of dusty plasmas. These unstable modes are well discriminated and plotted as a function of the density of the grains in dusty plasma and their radius. Temperature gradients and charge fluctuation have been ignored.
DECaNT: Simulation tool for diffusion of excitons in carbon nanotube films
Authors: Belling S. W. , Li Y. C. , Davoody A. H. , Gabourie A. J. , Knezevic I.
Published: February 2021

We present the numerical tool DECaNT (Diffusion of Excitons in Carbon NanoTubes) that simulates exciton transport in thin films of carbon nanotubes. Through a mesh of nanotubes generated using the Bullet Physics C++ library, excitons move according to an ensemble Monte Carlo algorithm, with the scattering rates that account for tube chirality, orientation, and distance. We calculate the diffusion tensor from the position–position correlation functions and analyze its anisotropy and dependence on the film composition, morphology, and defect density.
Machine-learning-assisted electron-spin readout of nitrogen-vacancy center in diamond
Authors: Qian Peng , Lin Xue , Zhou Feifei , Ye Runchuan , Ji Yunlan , Chen Bing , Xie Guangjun , Xu Nanyang
Published: February 2021

Machine learning is a powerful tool in finding hidden data patterns for quantum information processing. Here, we introduce this method into the optical readout of electron-spin states in diamond via single-photon collection and demonstrate improved readout precision at room temperature. The traditional method of summing photon counts in a time gate loses all the timing information crudely. We find that changing the gate width can only optimize the contrast or the state variance, not both. In comparison, machine learning adaptively learns from time-resolved fluorescence data and offers the optimal data processing model that elaborately weights each time bin to maximize the extracted information. It is shown that our method can repair the processing result from imperfect data, reducing 7% in spin readout error while optimizing the contrast. Note that these improvements only involve recording photon time traces and consume no additional experimental time, and they are, thus, robust and free. Our machine learning method implies a wide range of applications in the precision measurement and optical detection of states.
Elastic moduli fluctuations predict wave attenuation rates in glasses
Authors: Kapteijns Geert , Richard David , Bouchbinder Eran , Lerner Edan
Published: February 2021

The disorder-induced attenuation of elastic waves is central to the universal low-temperature properties of glasses. Recent literature offers conflicting views on both the scaling of the wave attenuation rate Γ(ω) in the low-frequency limit (ω → 0) and its dependence on glass history and properties. A theoretical framework—termed Fluctuating Elasticity Theory (FET)—predicts low-frequency Rayleigh scattering scaling in đ spatial dimensions, Γ(ω) ∼ γ ω đ+1, where γ = γ(Vc) quantifies the coarse-grained spatial fluctuations of elastic moduli, involving a correlation volume Vc that remains debated. Here, using extensive computer simulations, we show that Γ(ω) ∼ γω3 is asymptotically satisfied in two dimensions ( đ = 2) once γ is interpreted in terms of ensemble—rather than spatial—averages, where Vc is replaced by the system size. In doing so, we also establish that the finite-size ensemble-statistics of elastic moduli is anomalous and related to the universal ω4 density of states of soft quasilocalized modes. These results not only strongly support FET but also constitute a strict benchmark for the statistics produced by coarse-graining approaches to the spatial distribution of elastic moduli.
Absence of a Dirac gap in ferromagnetic Crx(Bi0.1Sb0.9)2−xTe3
Authors: Kim Chung Koo , Denlinger Jonathan D. , Kundu Asish K. , Gu Genda , Valla Tonica
Published: February 2021

Magnetism breaks the time-reversal symmetry expected to open a Dirac gap in 3D topological insulators that consequently leads to the quantum anomalous Hall effect. The most common approach of inducing a ferromagnetic state is by doping magnetic 3d elements into the bulk of 3D topological insulators. In Cr0.15(Bi0.1Sb0.9)1.85Te3, the material where the quantum anomalous Hall effect was initially discovered at temperatures much lower than the ferromagnetic transition, TC, the scanning tunneling microscopy studies have reported a large Dirac gap of ∼20–100 meV. The discrepancy between the low temperature of quantum anomalous Hall effect (≪TC) and large spectroscopic Dirac gaps (≫TC) found in magnetic topological insulators remains puzzling. Here, we used angle-resolved photoemission spectroscopy to study the surface electronic structure of the pristine and potassium doped surface of Cr0.15(Bi0.1Sb0.9)1.85Te3. Upon potassium deposition, the p-type surface state of the pristine sample was turned into an n-type, allowing the spectroscopic observation of Dirac point. We find a gapless surface state, with no evidence of a large Dirac gap reported in tunneling studies.
The scaling of kinetic and transport behaviors in the solution-phase chemistry of a plasma–liquid interface
Authors: Delgado Hernan E. , Brown Gabriel H. , Bartels David M. , Rumbach Paul , Go David B.
Published: February 2021

The reactions at a plasma–liquid interface often involve species such as the solvated electron or the hydroxyl radical, which initiate the reduction or oxidation of solution-phase reactants (so-called scavengers) or are consumed by their own second-order recombination. Here, the mathematical scaling of the reaction–diffusion equations at the interface is used to obtain a characteristic time that can be used to determine the transition from highly efficient scavenger reduction or oxidation to lower efficiencies due to transport limitations. The characteristic time (tc) is validated using numerical solutions of the reaction–diffusion equations. When the scavenger kinetics are faster than second-order recombination, this characteristic transition time scales proportionally with the scavenger diffusivity (Ds) and the square of the scavenger bulk concentration (SB) and inversely proportional to the electron flux (J) squared; that is, tc = DsSB2F2/J2, where F is Faraday's constant. However, when the scavenger kinetics are comparable or slower than second-order recombination, this scaling does not hold. Extending this analysis to three-dimensional systems shows that the profile of the electron flux on the surface affects the spatial location where reactions are most effective. Finally, the assessment of the implications of these behaviors for the reactor design highlights how effectively controlling the electron flux and solution transport may be necessary to improve the efficiency of scavenger reactions.
3D structure–property correlations of electronic and energy materials by tomographic atomic force microscopy
Authors: Song Jingfeng , Zhou Yuanyuan , Huey Bryan D.
Published: February 2021

The ever-increasing complexity in the structure and design of functional materials systems and devices necessitates new imaging approaches with 3D characterization capabilities and nanoscale resolution. This Perspective provides a brief review of the tomographic atomic force microscopy technique and its recent applications in the 3D nanocharacterization of energy and electronic materials including hybrid perovskites, CdTe, and ferroelectric BiFeO3, and filamentary resistive memories as model systems. We also propose several challenges and opportunities for further developing and applying this emerging approach for investigating fundamental and applied phenomena in a broader scope of functional materials.
Stability of generalized Kolmogorov flow in a channel
Authors: Romanò Francesco
Published: February 2021

The Kolmogorov flow is a paradigmatic model flow used to investigate the transition from laminar to turbulent regimes in confined and, especially, in unbounded domains. It represents a solution of the forced Navier–Stokes equation, where the forcing term is sinusoidal. The resulting velocity profile is also sinusoidal with the same wavenumber of the forcing term. In this study, we generalize the Kolmogorov flow making use of a generic forcing term defined by a Fourier series that bridges the classical Kolmogorov flow to an arbitrary even-degree power-law profile. Thereafter, we perform a linear stability analysis on the power-law profiles for exponents, α=2, 4, 6, 8, and 10, and the corresponding generalized Kolmogorov flows, varying the truncation index K of the Fourier series. Several neutral stability curves are computed numerically for wall-bounded flows and the relevant critical conditions are compared in terms of critical Reynolds number, critical wavelength, and eigenspectrum at criticality. The most dangerous perturbations are thoroughly characterized, and we identify three qualitatively different most dangerous modes, depending on α, K, the Reynolds number, and the perturbation wavelength.