bluuebunny/crossref_metadata_2025 huggingface dataset:
Decision support for the quickest detection of critical COVID-19 phases
Authors: Braca Paolo , Gaglione Domenico , Marano Stefano , Millefiori Leonardo M. , Willett Peter , Pattipati Krishna
Published: April 2021

During the course of an epidemic, one of the most challenging tasks for authorities is to decide what kind of restrictive measures to introduce and when these should be enforced. In order to take informed decisions in a fully rational manner, the onset of a critical regime, characterized by an exponential growth of the contagion, must be identified as quickly as possible. Providing rigorous quantitative tools to detect such an onset represents an important contribution from the scientific community to proactively support the political decision makers. In this paper, leveraging the quickest detection theory, we propose a mathematical model of the COVID-19 pandemic evolution and develop decision tools to rapidly detect the passage from a controlled regime to a critical one. A new sequential test—referred to as MAST (mean-agnostic sequential test)—is presented, and demonstrated on publicly available COVID-19 infection data from different countries. Then, the performance of MAST is investigated for the second pandemic wave, showing an effective trade-off between average decision delay $$\Delta$$
Δ
and risk $$R$$
R
, where $$R$$
R
is inversely proportional to the time required to declare the need to take unnecessary restrictive measures. To quantify risk, in this paper we adopt as its proxy the average occurrence rate of false alarms, in that a false alarm risks unnecessary social and economic disruption. Ideally, the decision mechanism should react as quick as possible for a given level of risk. We find that all the countries share the same behaviour in terms of quickest detection, specifically the risk scales exponentially with the delay, $$R \sim \exp {(-\omega \Delta )}$$

R
∼
exp

(
-
ω
Δ
)

, where $$\omega$$
ω
depends on the specific nation. For a reasonably small risk level, say, one possibility in ten thousand (i.e., unmotivated implementation of countermeasures every 27 years, on the average), the proposed algorithm detects the onset of the critical regime with delay between a few days to 3 weeks, much earlier than when the exponential growth becomes evident. Strictly from the quickest-detection perspective adopted in this paper, it turns out that countermeasures against the second epidemic wave have not always been taken in a timely manner. The developed tool can be used to support decisions at different geographic scales (regions, cities, local areas, etc.), levels of risk, instantiations of controlled/critical regime, and is general enough to be applied to different pandemic time-series. Additional analysis and applications of MAST are made available on a dedicated website.
Production and properties of non-cytotoxic pyomelanin by laccase and comparison to bacterial and synthetic pigments
Authors: Lorquin Faustine , Ziarelli Fabio , Amouric Agnès , Di Giorgio Carole , Robin Maxime , Piccerelle Philippe , Lorquin Jean
Published: April 2021

Pyomelanin is a polymer of homogentisic acid synthesized by microorganisms. This work aimed to develop a production process and evaluate the quality of the pigment. Three procedures have been elaborated and optimized, (1) an HGA-Mn2+ chemical autoxidation (PyoCHEM yield 0.317 g/g substrate), (2) an induced bacterial culture of Halomonas titanicae through the 4-hydroxyphenylacetic acid-1-hydroxylase route (PyoBACT, 0.55 g/L), and (3) a process using a recombinant laccase extract with the highest level produced (PyoENZ, 1.25 g/g substrate) and all the criteria for a large-scale prototype. The chemical structures had been investigated by 13C solid-state NMR (CP-MAS) and FTIR. Car–Car bindings predominated in the three polymers, Car–O–Car (ether) linkages being absent, proposing mainly C3-C6 (α-bindings) and C4-C6 (β-bindings) configurations. This work highlighted a biological decarboxylation by the laccase or bacterial oxidase(s), leading to the partly formation of gentisyl alcohol and gentisaldehyde that are integral parts of the polymer. By comparison, PyoENZ exhibited an Mw of 5,400 Da, was hyperthermostable, non-cytotoxic even after irradiation, scavenged ROS induced by keratinocytes, and had a highly DPPH-antioxidant and Fe3+-reducing activity. As a representative pigment of living cells and an available standard, PyoENZ might also be useful for applications in extreme conditions and skin protection.
Urinary microRNA biomarkers for detecting the presence of esophageal cancer
Authors: Okuda Yusuke , Shimura Takaya , Iwasaki Hiroyasu , Fukusada Shigeki , Nishigaki Ruriko , Kitagawa Mika , Katano Takahito , Okamoto Yasuyuki , Yamada Tamaki , Horike Shin-ichi , Kataoka Hiromi
Published: April 2021

Esophageal cancer (EC) including esophageal squamous cell carcinoma (ESCC) and adenocarcinoma (EAC) generally exhibits poor prognosis; hence, a noninvasive biomarker enabling early detection is necessary. Age- and sex-matched 150 healthy controls (HCs) and 43 patients with ESCC were randomly divided into two groups: 9 individuals in the discovery cohort for microarray analysis and 184 individuals in the training/test cohort with cross-validation for qRT-PCR analysis. Using 152 urine samples (144 HCs and 8 EACs), we validated the urinary miRNA biomarkers for EAC diagnosis. Among eight miRNAs selected in the discovery cohort, urinary levels of five miRNAs (miR-1273f, miR-619-5p, miR-150-3p, miR-4327, and miR-3135b) were significantly higher in the ESCC group than in the HC group, in the training/test cohort. Consistently, these five urinary miRNAs were significantly different between HC and ESCC in both training and test sets. Especially, urinary miR-1273f and miR-619-5p showed excellent values of area under the curve (AUC) ≥ 0.80 for diagnosing stage I ESCC. Similarly, the EAC group had significantly higher urinary levels of these five miRNAs than the HC group, with AUC values of approximately 0.80. The present study established novel urinary miRNA biomarkers that can early detect ESCC and EAC.
Peripheral vasoreactivity in acute ischemic stroke with hemiplegia
Authors: Wang Su Jeong , Lee Chan-Hyuk , Kang Hyun Goo , Kim Ko Woon , Kim Minjoo , Jeong Hwan-Jeong , Shin Byoung-Soo
Published: April 2021

The association between vasomotor tone of the peripheral arteries and cerebral hemisphere function has not been established. This study analyzed the peripheral vasoreactivity of patients with acute ischemic stroke and hemiplegia using a modified Raynaud scan, which is a new technology for blood flow measurement. In this retrospective case–control study, we examined patients with unilateral weakness consistent with ischemic lesions who underwent brain magnetic resonance imaging and modified Raynaud scanning within five days from the onset of symptoms. The modified Raynaud scan was used to quantify the radioactivity of the bilateral fingertips during rest and cooling-heating thermal stress conditions and estimate vasoreactivity based on the change in the blood amount per time under rest-thermal stress. The subjects were classified into the preserved and impaired groups based on their degrees of vasomotor reaction. Based on the modified Raynaud scanning, 37 (mean age = 69.1 ± 10.6) and 32 (mean age = 62.6 ± 11.8) subjects were allocated to the preserved and impaired groups, respectively. Binary logistic regression showed that the affected limb edema (odds ratio (OR) 6.15; confidence interval (CI) 1.40–26.97;p = 0.016) and anterior circulation (OR 3.68; CI 1.01–13.48;p = 0.049) were associated with impaired vasoreactivity. The modified Raynaud scans confirmed that central lesions in the anterior circulation with hemiparesis may influence the vasoreactivity of edematous peripheral arteries. These results may inform treatment and rehabilitation for stroke patients with hemiparesis.
Author Correction: Leprosy incidence and risk estimates in a 33-year contact cohort of leprosy patients
Authors: Hacker Mariana Andrea , Sales Anna Maria , Duppre Nádia Cristina , Sarno Euzenir Nunes , Moraes Milton Ozório
Published: April 2021

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Machine learning prediction of blood alcohol concentration: a digital signature of smart-breathalyzer behavior
Authors: Aschbacher Kirstin , Hendershot Christian S. , Tison Geoffrey , Hahn Judith A. , Avram Robert , Olgin Jeffrey E. , Marcus Gregory M.
Published: April 2021

Excess alcohol use is an important determinant of death and disability. Machine learning (ML)-driven interventions leveraging smart-breathalyzer data may help reduce these harms. We developed a digital phenotype of long-term smart-breathalyzer behavior to predict individuals’ breath alcohol concentration (BrAC) levels trained on data from a smart breathalyzer. We analyzed roughly one million datapoints from 33,452 users of a commercial smart-breathalyzer device, collected between 2013 and 2017. For validation, we analyzed the associations between state-level observed smart-breathalyzer BrAC levels and impaired-driving motor vehicle death rates. Behavioral, geolocation-based, and time-series-derived features were fed to an ML algorithm using training (70% of the cohort), development (10% of the cohort), and test (20% of the cohort) sets to predict the likelihood of a BrAC exceeding the legal driving limit (0.08 g/dL). States with higher average BrAC levels had significantly higher alcohol-related driving death rates, adjusted for the number of users per state B (SE) = 91.38 (15.16), p < 0.01. In the independent test set, the ML algorithm predicted the likelihood of a given user-initiated BrAC sample exceeding BrAC ≥ 0.08 g/dL, with an area under the curve (AUC) of 85%. Highly predictive features included users’ prior BrAC trends, subjective estimation of their BrAC (or AUC = 82% without the self-estimate), engagement and self-monitoring, time since the last measure, and hour of the day. In conclusion, an ML algorithm successfully quantified a digital phenotype of behavior, predicting naturalistic BrAC levels exceeding 0.08 g/dL (a threshold associated with alcohol-related harm) with good discrimination capability. This result establishes a foundation for future research on precision behavioral medicine digital health interventions using smart breathalyzers and passive monitoring approaches.
Sn14O11Br6: a promising birefringent material with a [Sn14O11Br6] layer
Authors: Lu Zixiu , Zhang Fangfang , Tudi Abudukadi , Yang Zhihua , Li Zijian , Pan Shilie
Published: April 2021

A new tin(ii)oxybromide, Sn14O11Br6 (TOB), with two-dimensional [Sn14O11Br6] layers and large birefringence.
Cytosolic delivery of gadolinium via photoporation enables improved in vivo magnetic resonance imaging of cancer cells
Authors: Harizaj Aranit , Descamps Benedicte , Mangodt Christophe , Stremersch Stephan , Stoppa Arianna , Balcaen Lieve , Brans Toon , De Rooster Hilde , Devriendt Nausikaa , Fraire Juan C. , Bolea-Fernandez Eduardo , De Wever Olivier , Willaert Wouter , Vanhaecke Frank , Stevens Christian V. , De Smedt Stefaan C. , Roman Bart , Vanhove Christian , Lentacker Ine , Braeckmans Kevin
Published: April 2021

Nanoparticle-sensitized photoporation for safe and efficient cytosolic delivery of gadolinium chelates, enabling high-contrast in vivo cell tracking of cells by magnetic resonance imaging.
Novel SrGd2Al2O7:Mn4+, Nd3+, and Yb3+ phosphors for c-Si solar cells
Authors: Xu Yonghui , Zhang Liang , Dong Langping , Yin Shuwen , Wu Xiudi , You Hongpeng
Published: April 2021

Novel NIR phosphors possess broadband absorption in the UV-Vis region and strong NIR emission, matching well with the spectral response of the c-Si solar cell and having a potential application for the c-Si solar cell.
Reinforcement of a BiVO4 anode with an Fe2O3 underlayer for photoelectrochemical water splitting
Authors: Ho-Kimura SocMan , Luo Wenjun
Published: April 2021

An Fe2O3/BiVO4 heterojunction was found to be successfully formed by placing a haematite underlayer on a BiVO4 anode. This composite anode has a significant improvement in PEC photocurrent in the low bias region.
Characterization of tolloid-mediated cleavage of the GDF8 procomplex
Authors: McCoy Jason C. , Goebel Erich J. , Thompson Thomas B.
Published: April 2021

Growth differentiation factor 8 (GDF8), a.k.a. myostatin, is a member of the larger TGFβ superfamily of signaling ligands. GDF8 has been well characterized as a negative regulator of muscle mass. After synthesis, GDF8 is held latent by a noncovalent complex between the N-terminal prodomain and the signaling ligand. Activation of latent GDF8 requires proteolytic cleavage of the prodomain at residue D99 by a member of the tolloid family of metalloproteases. While tolloid proteases cleave multiple substrates, they lack a conserved consensus sequence. Here, we investigate the tolloid cleavage site of the GDF8 prodomain to determine what residues contribute to tolloid recognition and subsequent proteolysis. Using sequential alanine mutations, we identified several residues adjacent to the scissile bond, including Y94, that when mutated, abolish tolloid-mediated activation of latent GDF8. Using the astacin domain of Tll1 (Tolloid Like 1) we determined that prodomain mutants were more resistant to proteolysis. Purified latent complexes harboring the prodomain mutations, D92A and Y94A, impeded activation by tolloid but could be fully activated under acidic conditions. Finally, we show that co-expression of GDF8 WT with prodomain mutants that were tolloid resistant, suppressed GDF8 activity. Taken together our data demonstrate that residues towards the N-terminus of the scissile bond are important for tolloid-mediated activation of GDF8 and that the tolloid-resistant version of the GDF8 prodomain can function dominant negative to WT GDF8.
Dual-band beam steering THz antenna using active frequency selective surface based on graphene
Authors: Yang Yao-Jia , Wu Bian , Zhao Yu-Tong , Chi-Fan
Published: April 2021

A dual-band independently beam steering THz antenna is presented, which is composed of a broadband omnidirectional monopole source antenna surrounded by six hexagonal active frequency selective surface (AFSS) screens with switchable filtering response in two bands. By controlling the chemical potential from 0 eV to 0.5 eV, the AFSS screen can achieve the conversion between high transmission (ON state) and almost total reflection (OFF state) at two frequency ranges independently. Therefore, the radiation beams of the THz antenna in two bands can be steered from 360° large angle scanning and omnidirectional radiation with flexible combinations.
Januskinase-Inhibitoren in der Kinderrheumatologie
Authors: Kühn Alexander , Horneff Gerd
Published: April 2021

Mit der Entwicklung von Januskinase (JAK)-Inhibitoren, einer neuen Klasse von „targeted synthetic (ts) disease modifying antirheumatic drugs (DMARDs)“, wurden innovative therapeutische Perspektiven geschaffen. Im Gegensatz zu Biologika, die als Antikörper oder Fusionsprotein ein einzelnes Zytokin extrazellulär, einen Zytokinrezeptor oder ein Oberflächenmolekül auf der Zelle blockieren, wirken JAK-Inhibitoren intrazellulär und vor allem breiter. Durch Inhibition von Tyrosinkinasen (JAK 1–3, Tyk 2) können sie den Signalweg von >50 Zytokinen unterbinden. Die JAK-Inhibitoren erweitern damit die Behandlungsoptionen bei rheumatischen Erkrankungen. Studien zu rheumatischen Erkrankungen bei Erwachsenen und erste Daten bei Kindern und Jugendlichen weisen auf eine im Vergleich zu Biologika gleichwertige oder sogar bessere Effektivität hin. In aktuell laufenden und zukünftigen Studien wird sich herausstellen, welche „Jakinibs“ die beste Wirkung-Nebenwirkungs-Relation aufweisen.
Distinct Prognostic Factors in Sporadic and Multiple Endocrine
Neoplasia Type 1-Related Pancreatic Neuroendocrine Tumors
Authors: Kfir Sapir Kon , Halperin Reut , Percik Ruth , Uri Inbal , Halpern Naama , Shlomai Gadi , Laish Ido , Tirosh Amir , Tirosh Amit
Published: April 2021

Pancreatic neuroendocrine tumors (PNET) may develop sporadically or in the
context of hereditary syndromes. In patients with multiple endocrine neoplasia
type 1 (MEN1), PNET is the leading cause of death. Our aim was to compare the
mortality risk in sporadic and MEN1-related PNETs and identify high-risk
populations. A retrospective Surveillance, Epidemiology, and End Results
database analysis of patients with PNET was used. Patients with MEN1 were
defined by syn/metachronous pituitary adenoma. Clinical data were
retrieved, and all-cause mortality (ACM) risk was compared in univariate and
multivariable analyses. The cohort included 569 patients (46.6% males)
with sporadic (n=542) and MEN1-related (n=27) PNETs. Age at
diagnosis of MEN1-related PNET was significantly younger than with sporadic
PNETs (mean age 49.2±16.7 vs. 61.6±12.7 years, respectively; p
< 0.001). Survival analysis showed a trend for a better outcome
in patients with MEN1-related vs. sporadic PNET (Log-rank, p=0.09) and
in subgroup analysis for patients with advanced disease (p=0.08).
Furthermore, among patients followed expectantly, those with MEN1-related PNET
had lower ACM risk than their sporadic counterparts (p=0.08).
Multivariable analysis demonstrated lower ACM risk in patients diagnosed with
MEN1 (hazard ratio 0.35, 95% confidence interval 0.11–1.2,
p=0.09), further supporting the trend detected in the univariate
analysis. In conclusion, our study demonstrates the distinct clinical profile of
patients with MEN1-related PNET compared to sporadic disease and emphasizes the
expertise required to accurately manage patients with PNET in this rare context.
The cautious decision-making required before embarking on surgical intervention
is further emphasized in this robust analysis of a large cancer database.
The Volatility Effect in China
Authors: Blitz David , Hanauer Matthias X. , van Vliet Pim
Published: April 2021

This paper shows that low-risk stocks significantly outperform high-risk stocks in the local China A-share market. The main driver of this low-risk anomaly is volatility, and not beta. A Fama–French style VOL factor is not explained by the Fama–French–Carhart factors, and has the strongest stand-alone performance among all these factors. Our findings are robust across sectors and over time, and consistent with previous empirical evidence for the US and international markets. Moreover, the VOL premium exhibits excellent investability characteristics, as it involves a low turnover and remains strong when applied to only the largest and most liquid stocks. Our results imply that the volatility effect is a highly pervasive phenomenon, and that explanations should be able to account for its presence in highly institutionalized markets, such as the US, but also in the Chinese market where private investors dominate trading.
Hamiltonian systems, Toda lattices, solitons, Lax pairs on weighted Z-graded graphs
Authors: Mograby Gamal , Derevyagin Maxim , Dunne Gerald V. , Teplyaev Alexander
Published: April 2021

We consider discrete one-dimensional nonlinear equations and present the procedure of lifting them to Z-graded graphs. We identify conditions that allow one to lift one-dimensional solutions to solutions on graphs. In particular, we prove the existence of solitons for static potentials on graded fractal graphs. We also show that even for a simple example of a topologically interesting graph, the corresponding non-trivial Lax pairs and associated unitary transformations do not lift to a Lax pair on the Z-graded graph.
Trajectory and attitude study of a skipping stone
Authors: Tang Jie , Zhao Kun , Chen Huatao , Cao Dengqing
Published: April 2021

Although skipping stones seems like a time-honored pastime, an in-depth study of this game is of vital importance for the understanding of the water landing of space flight re-entry vehicles and aircraft, hull slamming, antitorpedo and antisubmarine water entry, etc. This study is devoted to scrutinize the motion rules involved in stone skipping theoretically and experimentally. A new physical model of the skipping stones is first developed by the Lagrange equation, in which both the Magnus effect and gyro effect are taken into consideration. Then, based on the theoretical model, the motion mechanism of a disk under the coupling effect of translation and spinning is revealed. The physical mechanism of the “trout” regime and trajectory deflection are discussed during the continuous bounce. Motion rules of the attitude and trajectory involved in the stone-skipping phenomenon are also presented. Furthermore, an experimental setup is established to verify the theoretical analysis, where for convenience in analyzing, an aluminum disk is employed instead of a real stone. Finally, the theoretical and experimental results are analyzed synthetically. The results reveal that (a) appropriate attack angles and horizontal velocities are the key factors in generating sufficient hydrodynamic forces to satisfy the conditions of bounce (a>3.80g); (b) the gyro effect can guarantee the stability of the attack angle, which creates favorable conditions for the continuous bounce of the stone; and (c) the trajectory deflection results from the combination of the gyro effect and the Magnus effect. In the low-spin zone (Ω<18 rot s−1), the Magnus effect plays a dominant role in the trajectory deflection, while in the high-spin zone (Ω>18 rot s−1), the gyro effect plays the vital role. Besides, the deflection direction of trajectory is controlled by the rotational direction of the stone (clockwise or counterclockwise).
Optoelectronic intelligence
Authors: Shainline Jeffrey M.
Published: April 2021

General intelligence involves the integration of many sources of information into a coherent, adaptive model of the world. To design and construct hardware for general intelligence, we must consider principles of both neuroscience and very-large-scale integration. For large neural systems capable of general intelligence, the attributes of photonics for communication and electronics for computation are complementary and interdependent. Using light for communication enables high fan-out as well as low-latency signaling across large systems with no traffic-dependent bottlenecks. For computation, the inherent nonlinearities, high speed, and low power consumption of Josephson circuits are conducive to complex neural functions. Operation at 4 K enables the use of single-photon detectors and silicon light sources, two features that lead to efficiency and economical scalability. Here, I sketch a concept for optoelectronic hardware, beginning with synaptic circuits, continuing through wafer-scale integration, and extending to systems interconnected with fiber-optic tracts, potentially at the scale of the human brain and beyond.
Radiation hardened H-diamond MOSFET (RADDFET) operating after 1 MGy irradiation
Authors: Yamaguchi Takahiro , Umezawa Hitoshi , Ohmagari Shinya , Koizumi Hitoshi , Kaneko Junichi H.
Published: April 2021

Although the surface conductivity of a hydrogen-terminated diamond (H-diamond) enables production of high-performance field effect transistors (FETs), the total ionizing dose effect is yet to be clarified for H-diamond FETs. We fabricated a RADiation hardened H-terminated Diamond metal–oxide–semiconductor FET (RADDFET) using an oxide gate dielectric deposited at high temperatures. This paper describes its stable operation after 1 MGy irradiation. H-diamond films were prepared using microwave plasma assisted chemical vapor deposition with a p+ layer for reduction of contact resistance. The Al2O3 passivation layer was deposited by atomic layer deposition at 450 °C to achieve operation in high-temperature environment; then a RADDFET was fabricated on them using a Ru electrode. Several current–voltage characteristics were compared before irradiation and after certain dose levels up to 1 MGy. Before they were irradiated in air, the dose rate was measured using a cellulose triacetate film dosimeter. Even after an irradiation level of 1 MGy, the off-current at gate bias voltage (VG) of 3 V was more than six orders of magnitude lower than the on-current at VG of −6 V. Variation of the drain current density (JDS) in the measurements was less than 2%. The threshold voltage shifted approximately 1.7 V with 3 kGy of x ray irradiation, but no marked degradation was confirmed at higher levels. The subthreshold swings were 238, 215, and 264 mV/decade, respectively, after irradiation of 100 kGy, 300 kGy, and 1 MGy. These results indicate that the RADDFET was very stable at higher doses after initial stabilization.
Structure and dynamical properties of two-dimensional dusty plasmas on one-dimensional periodic substrates
Authors: Feng Yan , Li Wei , Reichhardt C. , Reichhardt C. J. O. , Murillo M. S.
Published: April 2021

In the presence of the substrate, various structural and dynamical properties of two-dimensional dusty plasma (2DDP) were investigated using Langevin dynamical simulations. This paper reviews a series of results of the structural and dynamical properties of 2DDP modified by one-dimensional periodic substrates (1DPSs) as follows. First, when the depth of the 1DPS increases gradually, it is found that the static structural order of 2DDP along each potential well of the 1DPS increases first and then decreases gradually. When the width of the 1DPS increases gradually, the particle arrangement in each potential well of the 1DPS changes from one straight row gradually to two rows, including the stable zigzag structure. Second, when there are two rows in each potential well of the 1DPS, the phonon spectra are split into two branches, corresponding to the breathing and sloshing modes, respectively. In addition, due to the pure repulsion between dust particles, from the obtained phonon spectra, the sloshing wave propagates backward at small wave numbers. Third, the calculated mean square displacement shown that, at the intermediate timescale between the initial ballistic and final diffusive motions, the particle motion tends to be more subdiffusive while the depth of the 1DPS increases. While the width of the 1DPS increases gradually, the long-time diffusive motion first increases, then decreases, and finally increases again, exhibiting the oscillation-like diffusion, due to the stable zigzag structure. Finally, when an external direct-current driving force is applied on all particles of 2DDP, three different depinning phases are discovered, which are the pinned, disordered plastic flow, and moving ordered states, respectively, as the driving force increases from zero. In addition, the continuous/discontinuous property of the phase transition between these different depinning states is investigated, showing that the transition property is modulated by the depth of the applied 1DPS.
Ultra-broadband sound absorption of a hierarchical acoustic metamaterial at high temperatures
Authors: Li Zhendong , Wang Zhonggang , Guo Zichao , Wang Xinxin , Liang Xifeng
Published: April 2021

We develop a hierarchical acoustic metamaterial with ultra-broadband sound absorption and promising applications at high temperatures as a super sound absorber. The proposed metamaterial is constructed through tailoring structural configurations by vertex-based hierarchy. The hierarchical design enables the acoustic metamaterial to achieve an excellent successive absorption spectrum in the low- to mid-frequency range from 0.58 kHz to 2.04 kHz in the first order and 0.64 kHz to 3.42 kHz in the second order, respectively. The sound absorption performance at high temperatures is predicted by means of theoretical and numerical approaches, and the models are validated by experimental measurements at room temperature. This work provides insight and opportunities into the role of structural hierarchy in designing acoustic metamaterials equipped with extraordinary absorption properties, illustrating an unprecedented capability of the hierarchical acoustic metamaterial.
Investigation of thermocapillary migration of nanodroplets using molecular dynamics
Authors: Frank M. , Lappa M. , Capobianchi P.
Published: April 2021

Molecular dynamics is used to investigate the thermocapillary motion of a water nanodroplet suspended in benzene subjected to a constant temperature gradient. This framework lets us identify the average behavior of the fluid particles by revealing their mean evolution. We connect such statistics to the behavior of the temporally evolving nanodroplet, thereby providing a microphysical foundation to existing macroscopic models that rely on the assumption of continuum. It is shown that, despite the significant Brownian effects, the droplet exhibits the macrophysical expected behavior, i.e., it migrates toward the direction of the imposed temperature gradient. Thermophoretic effects are negligible and the functional relationships involved in such a process well resemble those of available analytical results. Additionally, we provide molecular dynamics calculations of the viscosity, thermal conductivity, and interfacial tension of benzene [using the Optimized Potentials for Liquid Simulations—All Atom (OPLSAA) molecular model] and water using the Transferable Intermolecular Potential with 4 Points (TIP4P) model at different temperatures and pressures. These findings will serve as a good reference for future simulations of similar molecular models.
Role of octahedral deformation in the broad-band emission in Mn-doped lead halide perovskite: First-principles investigation for the case of CsPbX3 (X = Cl, Br, I)
Authors: Song Lingting , Huang Le , Xiao Wenbo , Li Jingbo
Published: April 2021

Doping manganese ions (Mn2+) in lead halide perovskites (LHPs) has been proven to be an efficient strategy to achieve excellent light-emitting performance. A self-trapped exciton on a MnX6 (X = Cl, Br, I) octahedron and associated energy transfer play critical roles in the broad-band emission of Mn-doped LHPs. In this work, we performed first-principles study on the effect of octahedral MnX6 deformation on the light emission in Mn-doped LHPs. It is revealed that the broad-band luminescence peak is associated with Mn 3d orbitals. Our results revealed that octahedral MnX6 deformation, which enhances the dispersion of the associated bands, plays an important role in the broad-band emission in Mn-doped LHPs. Furthermore, octahedral MnX6 deformation shows dependence on the halogen element and structural phase of LHPs. Our results proved that tuning octahedral MnX6 deformation is an efficient way to achieve the regulation of the luminescence performance of Mn-doped LHPs. Our predictive results may inspire further studies on the applications of doped Mn perovskites.
Time-dependent switching of the photon entanglement type using a driven quantum emitter–cavity system
Authors: Seidelmann T. , Reiter D. E. , Cosacchi M. , Cygorek M. , Vagov A. , Axt V. M.
Published: April 2021

The cascaded decay in a four-level quantum emitter is a well-established mechanism to generate polarization-entangled photon pairs, the building blocks of many applications in quantum technologies. The four most prominent maximally entangled photon pair states are the Bell states. In a typical experiment based on an undriven emitter, only one type of Bell state entanglement can be observed in a given polarization basis. Other types of Bell state entanglement in the same basis can be created by continuously driving the system by an external laser. In this work, we propose a protocol for time-dependent entanglement switching in a four-level quantum emitter–cavity system that can be operated by changing the external driving strength. By selecting different two-photon resonances between the laser-dressed states, we can actively switch back and forth between the different types of Bell state entanglement in the same basis as well as between entangled and nonentangled photon pairs. This remarkable feature demonstrates the possibility to achieve a controlled, time-dependent manipulation of the entanglement type that could be used in many innovative applications.
An alternative form of the fundamental plasma emission through the coalescence of Z-mode waves with whistlers
Authors: Ni Sulan , Chen Yao , Li Chuanyang , Sun Jicheng , Ning Hao , Zhang Zilong
Published: April 2021

Plasma emission (PE), i.e., electromagnetic radiation at the plasma frequency and its second harmonic, is a general process occurring in both astrophysical and laboratory plasmas. The prevailing theory presents a multi-stage process attributed to the resonant coupling of beam-excited Langmuir waves with ion-acoustic waves. Here, we examine another possibility of the fundamental PE induced by the resonant coupling of Z-mode and whistler (W) waves. Earlier studies have been controversial in the plausibility and significance of such process in plasmas. In this study, we show that the matching condition of three-wave resonant interaction (Z + W → O) can be satisfied over a wide regime of parameters based on the magnetoionic theory, demonstrate the occurrence of such process, and further evaluate the rate of energy conversion from the pumped Z or W mode to the fundamental O mode with particle-in-cell simulations of wave pumping. The study presents an alternative form of the fundamental PE, which could possibly play a role in various astrophysical and laboratory scenarios with both Z and W modes readily excited through the electron cyclotron maser instability.
Off-wall boundary conditions for large-eddy simulation based on near-wall turbulence prediction
Authors: Wang Hai-Ning , Huang Wei-Xi , Xu Chun-Xiao
Published: April 2021

Wall-modeled large-eddy simulation (LES) is currently the only affordable technique toward the eddy-resolving simulation of high-Reynolds number wall turbulence. Treatment of near-wall region in LES has drawn much attention in recent studies of wall turbulence and computational fluid dynamics. Traditional wall models typically relate the wall stress to the velocity through prescribed algebraic relations or the thin boundary layer equation. In the present study, we developed a new method for the treatment of near-wall region in LES based on the off-wall boundary conditions. The method combines the minimum flow units [Yin et al., “Prediction of near-wall turbulence using minimal flow unit,” J. Fluid Mech. 841, 654–673 (2018)] and the predictive inner–outer (PIO) model for wall turbulence [Marusic et al., “Predictive model for wall-bounded turbulent flow,” Science 329, 193–196 (2010)]. Fluctuating near-wall velocity field is predicted in real time to supply boundary conditions on the off-wall boundary. This method does not assume any velocity profile of the flow, but rather exploits the well-established universality of near-wall turbulence, and incorporates turbulent structures in the boundary conditions. We derived the expressions of the velocity and the subgrid-scale (SGS) stress boundary conditions in combination with the PIO model, and proved that the modulation effect and the fluctuating part of the SGS stress are not necessary for the off-wall boundary conditions. Through comparisons with other wall models, the current method is found to induce a shorter transition zone in the wall-normal direction. The validity and robustness of the method are verified by the reasonable simulation results of channel flows under different computational parameters.
Fin-shaped AlGaN/GaN high electron mobility magnetoresistive sensor device
Authors: Xia Lingxi , Ren Kailin , Huang Chih-Fang , Liang Yung C.
Published: April 2021

A good magnetic field sensor should exhibit high sensitivity, low power consumption, and low output offset to accurately detect small fields. In this work, the high sensitivity in magnetoresistance variation (ΔR) is achieved by the AlGaN/GaN fin-shaped high electron mobility structure, in comparison to that of planar structures. A physical based analysis is presented to describe the influence of the fin width dimension on the ΔR dependency under magnetic fields. The sensitivity is expressed as a function of geometric parameters, electron mobility, and two-dimensional electron sheet density, with relaxation of polarization, shoulder density distribution, and sidewall trapped charges considered. Devices were fabricated, and a high sensitivity is observed in laboratory measurements on devices at narrower fin widths. At the fin width of 50 nm, the measured device has a sensitivity of 0.76 Ω/μΤ2 at the magnetic flux of 85 μΤ. The sensor's power consumption is as low as 48 μW, and the minimum magnetic flux detectable is at 20 μΤ.
A compact and stable incidence-plane-rotating second harmonics detector
Authors: Kim S. H. , Jung S. , Seok B. , Kim Y. S. , Park H. , Otsu T. , Kobayashi Y. , Kim C. , Ishida Y.
Published: April 2021

We describe a compact and stable setup for detecting the optical second harmonics, in which the incident plane rotates with respect to the sample. The setup is composed of rotating Fresnel rhomb optics and a femtosecond ytterbium-doped fiber laser source operating at the repetition frequency of 10 MHz. The setup including the laser source occupies an area of 1 m2 and is stable so that the intensity fluctuation of the laser harmonics can be less than 0.2% for 4 h. We present the isotropic harmonic signal of a gold mirror of 0.5 pW and demonstrate the integrity and sensitivity of the setup. We also show the polarization-dependent six-fold pattern of the harmonics of a few-layer WSe2, from which we infer the degree of local-field effects. Finally, we describe the extensibility of the setup to investigate the samples in various conditions such as cryogenic, strained, ultrafast non-equilibrium, and high magnetic fields.
Two-color two-dimensional terahertz spectroscopy: A new approach for exploring even-order nonlinearities in the nonperturbative regime
Authors: Woerner Michael , Ghalgaoui Ahmed , Reimann Klaus , Elsaesser Thomas
Published: April 2021

Nonlinear two-dimensional terahertz (2D-THz) spectroscopy at frequencies of the emitted THz signal different from the driving frequencies allows for exploring the regime of (off-)resonant even-order nonlinearities in condensed matter. To demonstrate the potential of this method, we study two phenomena in the nonlinear THz response of bulk GaAs: (i) The nonlinear THz response to a pair of femtosecond near-infrared pulses unravels novel fourth- and sixth-order contributions involving interband shift currents, Raman-like excitations of transverse-optical phonon and intervalence-band coherences. (ii) Transient interband tunneling of electrons driven by ultrashort mid-infrared pulses can be effectively controlled by a low-frequency THz field with amplitudes below 50 kV/cm. The THz field controls the electron–hole separation modifying decoherence and the irreversibility of carrier generation.
Direct imaging of fluorescence enhancement in the gap between two gold nanodisks
Authors: Lin Hung-Ju , Xiang Hengyang , Xin Chenghao , Hu Zhelu , Billot Laurent , Gredin Patrick , Mortier Michel , Chen Zhuoying , González Maria-Ujué , García-Martín Antonio , Aigouy Lionel
Published: April 2021

We present an analysis of the optical coupling between two gold nanodisks by near-field fluorescence microscopy. This is achieved by simultaneously scanning and measuring the light emitted by a single Er3+/Yb3+ doped nanocrystal glued at the end of an atomic force microscope tip. The excitation of the nanocrystal was performed at λ = 975 nm via upconversion, and fluorescence was detected in the visible part of the spectrum at λ = 550 nm. For an isolated nanodisk, the near-field presents a two-lobe pattern oriented along the direction of the incident polarization. For two nanodisks with a sizable separation distance (385 nm) illuminated with the polarization along the interparticle axis, we observe a negative effect of the coupling with a slight decrease in fluorescence in the gap. For smaller gap values (195, 95, and 55 nm), a strong increase in fluorescence is observed as well as a reduced spatial localization of the field as the distance decreases. Finally, when the disks touch each other (0 nm), the dipolar–dipolar interaction between them disappears and no fluorescence enhancement occurs. A new plasmon mode is created at another wavelength. Our experimental results are in good agreement with numerical simulations of the near-field intensity distribution at the excitation wavelength on the surface of the structures. Combining fluorescence mapping and far-field scattering spectroscopy should be of strong interest to develop bio-chemical sensors based on field enhancement effects.
The effect of information about climate risk on property values
Authors: Hino Miyuki , Burke Marshall
Published: April 2021

Significance

Understanding whether markets efficiently price environmental risk is critical to policy design, particularly as key climate risks change rapidly. We conduct a nationwide analysis of the extent to which the US housing market prices information about flood risk contained in publicly available flood maps. Using data on millions of home sales, we find that information in these maps is not fully capitalized in property values. Lack of information appears to contribute to underpricing: More sophisticated commercial buyers and more risk-aware buyers respond more to floodplain information. This underpricing increases incentives to develop in hazardous places. Enhanced communication of flood risk could help ensure such risk is appropriately reflected in market outcomes.
Role of baits in reducing amount of insecticide usage in urban environment - mini review.
Authors: Partho Dhang Partho Dhang
Published: April 2021

The recent shift of human focus towards urban living has created opportunities for a few species of insects such as cockroaches, flies, mosquitoes, bed bugs, ticks, fleas, ants and termites to thrive. Consequent to this a need for insecticides has emerged, increasing chances of mass human exposure to insecticides. To counter this risk, usage of insecticide baits has recently become popular worldwide. Baits are target-specific and effective in killing insect pests directly through ingestion, but also through an indirect process termed 'transfer effect or secondary effect'. However, the most significant aspect of insect bait is the reduction of insecticide use within human vicinity, thus cutting down the chances of exposure to the unsuspecting population.
Structural and functional aspects, kinetic properties, specificity and diverse interactions of α-amylase inhibitors.
Authors: Rimaljeet Kaur Rimaljeet Kaur , Gupta A. K. , Narinder Kaur Narinder Kaur
Published: April 2021

Alpha-amylase inhibitors (α-Als) belong to the family of defence proteins which impede the digestion through their action on digestive α-amylases. These inhibitors have natural roles in the control of endogenous α-amylase activity or in defence against pathogens and pests. Certain inhibitors have been reported to act as antinutritional factors. The α-Als have been classified into seven different protein structural families that show remarkable structural diversity, leading to different modes of inhibition and different specificity profiles against various α-amylases. Specificity of inhibition is an important issue as the introduced inhibitor in transgenics should not adversely affect its own α-amylases. The present review addresses the diverse group of α-Als, various modes of inhibition during different enzyme-inhibitor interactions, kinetic properties, specificity and homology among different α-Als with the focus on exploring the diversity in characteristics of various α-Als. In addition, potential of transgenics with α-Als has also been discussed for insect resistance and controlling infestation.
What FXYDs fix
Authors: Habeck Michael , Poulsen Hanne
Published: April 2021

Na,K ATPases are modulated by FXYD subunits. What do the FXYDs affect, how do they do it, and what are their physiological impacts?
Generalized Additive Poisson Models for Quantifying Geological Factors Effect on The Earthquake Risk Mapping
Authors: Mukhti Tessy Octavia , Choiruddin Achmad , Purhadi
Published: April 2021

Cluster-type point process models are the popular model for modeling the arrangement of locations of earthquake occurrences. When a spatial trend is presence due to e.g. geological factors, the log-linear intensity of the point process is often considered to exploit inhomogeneity due to such factors. However, this could be a major drawback, especially in seismology when the relation between the intensity of earthquake occurrences and environmental covariates is not log-linear. In this paper, we consider the Cauchy cluster process with a log-additive intensity model to quantify two effects in modeling the distribution of locations of major earthquakes in Sulawesi-Maluku: (1) spatial trend due to geological covariates such as subduction zones, faults, and volcanoes and (2) clustering effect due to seismic activities. The Cauchy cluster process could detect the clustering effect even when the aftershocks are extremely distant to the mainshocks while log-additive intensity is a more flexible model to study inhomogeneity due to the environment. To estimate the parameters, we apply two-step estimation procedure, in the first step, we estimate the regression parameter corresponding to effects of the geological variables by maximum composite likelihood by involving penalized iteratively re-weighted least squares (PIRLS) technique, and in the second step, we obtain the cluster estimates by maximum second order composite likelihood. The results show that the active faults and volcanoes are significant covariates that trigger earthquakes, the estimated mainshock intensity is around 78, and the aftershocks are distributed around it with a distance of 15.2 km due to mainshock activity.
Examination of the dominant factor affecting the mixing in the microchannel
Authors: Kravtsova A Y , Ianko P E , Kashkarova M V , Bilsky A V , Kravtsov Y V
Published: April 2021

The effect of the input flowrate ratio and the Reynolds numbers in range from 10 to 300 on the mixing of liquids in a T-type micromixer was examined. Linear trends of mixing efficiency change on the ratio of input flowrates and Reynolds number are approximated. The most effective mixing (the mixing coefficient reaches 0.86) was obtained at Reynolds numbers 186 and 300 and the input flowrate ratio R = 1. It is determined that with equal input flowrate ratio, as the Reynolds number increases from 10 to 300, the mixing efficiency rises sharply: from 0.2 to 0.8 (for 0.5 < R < 1). Variation of the ratio of input flowrates at low Reynolds numbers in the range from 10 to 120 can lead to a significant increase in the mixing of liquids (Re = 47, the growth mixing from 0.22 to 0.67). With Reynolds numbers 186 and 300, as the input flowrate ratio increases from 0.1 to 1, the mixing ratio rises from 0.25–0.30 to 0.85–0.90.
Methodology of investigation of binary liquids in the unstable states
Authors: Rutin S B , Igolnikov A A
Published: April 2021

This work is devoted to the development of a measurement methodology for a new object in the thermophysics of extreme states – a partially-soluble binary liquid, which is short-term transferred to the region of unstable states above the diffusional spinodal. On an example of PPG-425/water solution having the lower critical solution temperature, the key hypothesis of the study on the general measurability of the properties of unstable solutions has been confirmed. The heating rate was varied from 105 to 106 K/s, and the pressure was varied from units of MPa to 100 MPa. The superheat of the solution with respect to the diffusional spinodal was up to 150 degrees. The conditions for the transition from measurements on pure components to measurements on the solution are formulated. The characteristic thermal patterns of the decay of unstable states depending on pressure and heating rate are revealed. The possibility of using this binary solution as a promising coolant in processes with powerful local heat release is assumed.