bluuebunny/crossref_metadata_2025 huggingface dataset:
Programmable photon pair source
Authors: Cui Liang , Wang Jinjin , Li Jiamin , Ma Mingyi , Ou Z. Y. , Li Xiaoying
Published: January 2022

Photon pairs produced by the pulse-pumped nonlinear parametric processes have been a workhorse of quantum information science (QIS). Engineering the spectral property of quantum states is crucial for practical QIS applications. However, photon pairs with desirable spectral properties are currently achieved with specially engineered optical hardware but with severely limited flexibility in tuning the spectral properties of the sources. Here, we demonstrate a spectrally programmable photon pair source by exploiting a two-stage nonlinear interferometer scheme with a computer-controlled phase device. The phase-control device can introduce phase shifts for spectral engineering by a programmable phase function that can be arbitrarily defined. When the phase function is properly designed, the output spectrum of the source can be freely customized and changed without replacing any hardware component in the system. Using this approach, we are able to program photon pairs with factorable positively correlated and negatively correlated spectra. In addition, we also realize a source of multi-dimensional three-channel spectrally factorable photon pairs. Our investigation provides a flexible and powerful new approach for engineering the mode profile of photon pairs and should find wide applications in QIS.
Simulation investigations on stepwise penetration of virtual anode in pseudospark discharge
Authors: Sun Guoxiang , Wang Xia , Yan Jiaqi , Shen Saikang , Shang Tianyi , Ding Weidong
Published: January 2022

Pseudospark discharge is a special low pressure discharge and has been widely used in the gas switch and electron beam sources. From experiments, when the work pressure is relatively low, the electron beam current or loop current generated by a pseudospark discharge usually has two or more peaks, which has not been fully explained. In this paper, a single-gap pseudospark discharge model is established using 2D kinetic plasma simulation code VSim to study this phenomenon. According to the simulation results, when the anode voltage is 20 kV and the helium pressure is 100 Pa, the current has two peaks, which is similar to the experimental results, accompanied by the stepwise penetration of the virtual anode. This is mainly related to the formation and disappearance of the potential barrier in the cathode hole region. The formation of the potential barrier is caused by the consumption of ions at the cathode hole, and the disappearance is caused by the increase in electrons in the cathode cavity. By classifying the electrons, it is found that the increased electrons are generated by secondary emission caused by ion bombardment on the wall of the cathode. The simulation results also show that the stepwise penetration of the virtual anode can be suppressed or eliminated by increasing the working gas pressure, the secondary electron yield of the cathode material, or the trigger intensity.
Optimizing charge-balanced pulse stimulation for desynchronization
Authors: Mau Erik T. K. , Rosenblum Michael
Published: January 2022

Collective synchronization in a large population of self-sustained units appears both in natural and engineered systems. Sometimes this effect is in demand, while in some cases, it is undesirable, which calls for control techniques. In this paper, we focus on pulsatile control, with the goal to either increase or decrease the level of synchrony. We quantify this level by the entropy of the phase distribution. Motivated by possible applications in neuroscience, we consider pulses of a realistic shape. Exploiting the noisy Kuramoto–Winfree model, we search for the optimal pulse profile and the optimal stimulation phase. For this purpose, we derive an expression for the change of the phase distribution entropy due to the stimulus. We relate this change to the properties of individual units characterized by generally different natural frequencies and phase response curves and the population’s state. We verify the general result by analyzing a two-frequency population model and demonstrating a good agreement of the theory and numerical simulations.
Hybrid nonlinear resonance in Hamiltonian systems
Authors: Ugulava A. , Chkhaidze S. , Kharshiladze O. , Mchedlishvili G.
Published: January 2022

An electronic system in an atom can be considered Hamiltonian only at times shorter than the spontaneous relaxation time. However, this time is sufficient for resonant action on the electronic system and for the implementation of the resonance inherent in Hamiltonian systems. In practice, there may be a case when it is expedient to use a hybrid approach to study nonlinear resonance, in which the classical theory can be used to calculate the action-dependent nonlinear resonance frequency, and the quantum theory can be used to calculate its correction. The use of such a hybrid approach becomes necessary when the resonant value of the action does not exceed Planck's constant many times. It is shown in the work that if the external electromagnetic field has the form of a periodic series of light pulses with a high duty cycle, then the phenomenon of nonlinear hybrid resonance leads to the appearance of a line in the low-frequency region of the electronic spectrum. The broadening of this line is determined using the rms quantum fluctuations.
Accelerated steady-state electrostatic particle-in-cell simulation of Langmuir probes
Authors: Werner Gregory R. , Robertson Scott , Jenkins Thomas G. , Chap Andrew M. , Cary John R.
Published: January 2022

First-principles particle-in-cell (PIC) simulation is a powerful tool for understanding plasma behavior, but this power often comes at great computational expense. Artificially reducing the ion/electron mass ratio is a time-honored practice to reduce simulation costs. Usually, this is a severe approximation. However, for steady-state collisionless, electrostatic (Vlasov–Poisson) systems, the solution with reduced mass ratio can be scaled to the solution for the real mass ratio, with no approximation. This “scaled mass” method, which works with already-existing PIC codes, can reduce the computation time for a large class of electrostatic PIC simulations by the square root of the mass ratio. The particle distributions of the resulting steady state must be trivially rescaled to yield the true distributions, but the self-consistent electrostatic field is independent of the mass ratio. This method is equivalent to “numerical timestepping,” an approach that evolves electron and ion populations with different time steps. Numerical timestepping can be viewed as a special case of the speed-limited PIC (SLPIC) method, which is not restricted to steady-state phenomena. Although the scaled-mass approach is simplest, numerical timestepping and SLPIC more easily generalize to include other effects, such as collisions. The equivalence of these new approaches is demonstrated by applying them to simulate a cylindrical Langmuir probe in electron–argon plasma, speeding up simulation by two orders of magnitude. Methods such as SLPIC can therefore play an invaluable role in interpreting probe measurements by including geometric effects, collisions, secondary emission, and non-Maxwellian distributions.
Effects of baffle on flow structure and cyclic variation in stirred tanks with Rushton turbine
Authors: Fan Ying , Sun Jiao , Jin Jie , Sun Kangfu , Zhang Hui , Chen Wenyi , Li Yibin
Published: January 2022

In order to reveal the effect of baffles on flow structure and cyclic variation stirred by Rushton turbines, particle image velocimetry experiments were performed in baffled and unbaffled stirred tanks. In a baffled tank, the peak value of time-averaged velocity obviously increases, the high velocity region enlarges significantly, and the fluctuation of fluid elements near the turbine increases significantly. In the 20° phase plane of the baffled tank, the high swirl strength region slightly enlarges, but the peak of phase-resolved swirl strength is lower. The peak value and high value regions of turbulent kinetic energy are larger in the baffled stirred tank at various phase planes. Using quadruple proper orthogonal decomposition, the flow field is decomposed into a small-scale part, a transition part, a large-scale part, and a mean part with different spatial scales. Adding the baffle, the mean part with largest spatial scale obviously increases (it is favorable for mass transfer at different liquid levels) and the transition part, which mainly includes the random fluctuation of a turbulent cascade, slightly enhances (it is conducive to diffusion). The main influence of cyclic variation for various blade passages is the flow with large-scale, and the standard deviation of time coefficients decreases by 3%–4% for the mean part and the large-scale part by adding the baffle.
Exploring optoelectronic properties of C-doped GaAs for photocathode application from first-principles calculation
Authors: Guo Xin , Shi Feng , Zhang Yijun , Zhang Ruoyu , Qiu Hongjin
Published: January 2022

In the preparation process of negative electron affinity GaAs photocathodes, the p-type doped property is beneficial to photoemission, and the doping element is usually Be or Zn. In fact, C-doped GaAs material has been widely used due to its high activation rate, extremely low diffusion coefficient, and good thermal stability, whereas the influence mechanism of the C dopant on the performance of the GaAs photocathode is still unclear. In order to investigate the substitutional effect on C-doped GaAs, electronic structures and optical properties along with angular distribution of emitted photoelectrons are obtained by utilizing first-principles calculation based on density functional theory. The results show that C-doped GaAs is more likely to form a p-type doped feature in which the C dopant forms new levels in the forbidden band and reduces the energy gap as well as increasing the absorption coefficient and decreasing the reflectivity in the visible light band. In addition, the electrons emitted from the Γ-valley for C-doped GaAs have better directivity than those for pure GaAs, which is mainly ascribed to the smaller effective electron mass in the Γ-valley.
Kuramoto model for populations of quadratic integrate-and-fire neurons with chemical and electrical coupling
Authors: Clusella Pau , Pietras Bastian , Montbrió Ernest
Published: January 2022

We derive the Kuramoto model (KM) corresponding to a population of weakly coupled, nearly identical quadratic integrate-and-fire (QIF) neurons with both electrical and chemical coupling. The ratio of chemical to electrical coupling determines the phase lag of the characteristic sine coupling function of the KM and critically determines the synchronization properties of the network. We apply our results to uncover the presence of chimera states in two coupled populations of identical QIF neurons. We find that the presence of both electrical and chemical coupling is a necessary condition for chimera states to exist. Finally, we numerically demonstrate that chimera states gradually disappear as coupling strengths cease to be weak.
Ab initio calculations in atoms, molecules, and solids, treating spin–orbit coupling and electron interaction on an equal footing
Authors: Eskridge Brandon , Krakauer Henry , Shi Hao , Zhang Shiwei
Published: January 2022

We incorporate explicit, non-perturbative treatment of spin–orbit coupling into ab initio auxiliary-field quantum Monte Carlo (AFQMC) calculations. The approach allows a general computational framework for molecular and bulk systems in which material specificity, electron correlation, and spin–orbit coupling effects can be captured accurately and on an equal footing, with favorable computational scaling vs system size. We adopt relativistic effective-core potentials that have been obtained by fitting to fully relativistic data and that have demonstrated a high degree of reliability and transferability in molecular systems. This results in a two-component spin-coupled Hamiltonian, which is then treated by generalizing the ab initio AFQMC approach. We demonstrate the method by computing the electron affinity in Pb, the bond dissociation energy in Br2 and I2, and solid Bi.
Reflectance of rhenium as a function of pressure in a diamond anvil cell
Authors: Song Jing , Chuvashova Irina , Silvera Isaac F.
Published: January 2022

We have measured the reflectance of rhenium in the visible region to pressures up to 100 GPa in a diamond anvil cell (DAC). By photographing the reflecting surface, we visually show that there are challenges to obtaining accurate values in a DAC for several reasons, including cupping of the diamonds and roughening of the surface with the increase in pressure. We propose some useful procedures, such as careful alignment of the incident light and using thin gaskets to minimize cupping of the diamonds as well as measurement in the central region of the diamond culet. We also show that knowledge of the reflectance of rhenium can overcome the problem of absorption of light by diamonds when studying the reflectance of materials at high pressure in a DAC.
Limitation in velocity of converging shock wave
Authors: Chefranov Sergey G. , Krasik Yakov E. , Rososhek Alexander
Published: January 2022

The commonly applied self-similar solution of the problem of the converging shock wave (shock) evolution with constant compression of the medium behind the shock front results in an unlimited increase in the medium velocity in the vicinity of the implosion. In this paper, the convergence of cylindrical shocks in water is analyzed using the mass conservation law, when the water compression behind the shock front is a variable. The model predicts a finite range of radii, which depends on the adiabatic index of water and where the increase in pressure exceeds the sum of the change in the kinetic and internal energy densities behind the shock front. In this range of radii, only the finite increase in the shock and water flow velocities is realized.
Spin dynamics driven by ultrafast laser-induced heating of iron garnet in high magnetic fields
Authors: Dolgikh I. A. , Formisano F. , Prabhakara K. H. , Logunov M. V. , Zvezdin A. K. , Christianen P. C. M. , Kimel A. V.
Published: January 2022

Femtosecond laser excitation heats a ferrimagnetic iron garnet across the compensation temperature and decreases the magnetizations of the constituting Fe3+ sublattices. Here, we explore the heat-induced magnetization dynamics in the ferrimagnet at different points in the H-T phase diagram. For magnetic field strengths high enough to promote a state with non-collinear magnetizations of the sublattices, the dynamics occurs on a sub-ns timescale, governed by the effective spin–lattice interaction throughout the whole Brillouin zone of the spin excitations. When the field is low and the magnetizations are collinear, the heating alone is not sufficient to initiate the dynamics. In that case, the dynamics can only start after the magnetizations experience an initial kick, which occurs on the timescale of the spin–lattice interaction in the center of the Brillouin zone, leading to a substantial delay of the response of the spins to the thermal excitation.
MOCVD growth of MgGa2O4 thin films for high-performance solar-blind UV photodetectors
Authors: Hou Qichao , Liu Kewei , Han Dongyang , Zhu Yongxue , Chen Xing , Li Binghui , Liu Lei , Shen Dezhen
Published: January 2022

Epitaxial MgGa2O4 thin films with a bandgap of 5.18 eV were grown on the c-plane sapphire substrate by using metal organic chemical vapor deposition. The structure, optical, electronic, and optoelectronic properties of MgGa2O4 thin films have been investigated before and after high-temperature annealing in an oxygen or nitrogen atmosphere. In particular, the O2-annealed MgGa2O4 thin film reveals a high crystalline quality and a low concentration of oxygen vacancies. Moreover, a quick response speed (tr = 20 ns, td = 400 ns), a low dark current (∼17 pA at 10 V), and a high UV/Visible rejection ratio (>105) can be demonstrated in the O2-annealed MgGa2O4 photodetector, indicating the excellent solar-blind ultraviolet (SBUV) photodetection characteristics. The effect of annealing atmosphere on the photoelectric properties of the film and its physical mechanism were studied. This research provides an effective way to realize high-performance SBUV photodetectors and opens up the application of MgGa2O4 spinel in the field of semiconductor optoelectronic and microelectronic devices.
Moving boundary truncated grid method for electronic nonadiabatic dynamics
Authors: Lu Chun-Yaung , Lee Tsung-Yen , Chou Chia-Chun
Published: January 2022

The moving boundary truncated grid method is developed to study the wave packet dynamics of electronic nonadiabatic transitions between a pair of diabatic potential energy surfaces. The coupled time-dependent Schrödinger equations (TDSEs) in the diabatic representation are integrated using adaptive truncated grids for both the surfaces. As time evolves, a variable number of grid points fixed in space are activated and deactivated without any advance information of the wave packet dynamics. Essential features of the truncated grid method are first illustrated through applications to three one-dimensional model problems, including the systems of single avoided crossing, dual avoided crossing, and extended coupling region with reflection. As a demonstration for chemical applications, the truncated grid method is then employed to study the dynamics of photoisomerization of retinal in rhodopsin described by a two-electronic-state two-dimensional model. To demonstrate the capability of the truncated grid method to deal with the electronic nonadiabatic problem in high dimensionality, we consider a multidimensional electronic nonadiabatic system in two, three, and four dimensions. The results indicate that the correct grid points are automatically activated to capture the growth and decay of the wave packets on both of the surfaces. Therefore, the truncated grid method greatly decreases the computational effort to integrate the coupled TDSEs for multidimensional electronic nonadiabatic systems.
A general statistical mechanical model for fluid system thermodynamics: Application to sub- and super-critical water
Authors: Zanetti-Polzi Laura , Daidone Isabella , Amadei Andrea
Published: January 2022

We propose in this paper a theoretical model for fluid state thermodynamics based on modeling the fluctuation distributions and, hence, the corresponding moment generating functions providing the free energy of the system. Using the relatively simple and physically coherent gamma model for the fluctuation distributions, we obtain a complete theoretical equation of state, also giving insight into the statistical/molecular organization and phase or pseudo-phase transitions occurring under the sub- and super-critical conditions, respectively. Application to sub- and super-critical fluid water and a comparison with the experimental data show that this model provides an accurate description of fluid water thermodynamics, except close to the critical point region where limited but significant deviations from the experimental data occur. We obtain quantitative evidence of the correspondence between the sub- and super-critical thermodynamic behaviors, with the super-critical water pseudo-liquid and pseudo-gas phases being the evolution of the sub-critical water liquid and gas phases, respectively. Remarkably, according to our model, we find that for fluid water the minimal subsystem corresponding to either the liquid-like or the gas-like condition includes an infinite number of molecules in the sub-critical regime (providing the expected singularities due to macroscopic phase transitions) but only five molecules in the super-critical regime (coinciding with the minimal possible hydrogen-bonding cluster), thus suggesting that the super-critical regime be characterized by the coexistence of nanoscopic subsystems in either the pseudo-liquid or the pseudo-gas phase with each subsystem fluctuating between forming and disrupting the minimal hydrogen-bonding network.
Permutationally invariant polynomial regression for energies and gradients, using reverse differentiation, achieves orders of magnitude speed-up with high precision compared to other machine learning methods
Authors: Houston Paul L. , Qu Chen , Nandi Apurba , Conte Riccardo , Yu Qi , Bowman Joel M.
Published: January 2022

Permutationally invariant polynomial (PIP) regression has been used to obtain machine-learned potential energy surfaces, including analytical gradients, for many molecules and chemical reactions. Recently, the approach has been extended to moderate size molecules with up to 15 atoms. The algorithm, including “purification of the basis,” is computationally efficient for energies; however, we found that the recent extension to obtain analytical gradients, despite being a remarkable advance over previous methods, could be further improved. Here, we report developments to further compact a purified basis and, more significantly, to use the reverse differentiation approach to greatly speed up gradient evaluation. We demonstrate this for our recent four-body water interaction potential. Comparisons of training and testing precision on the MD17 database of energies and gradients (forces) for ethanol against numerous machine-learning methods, which were recently assessed by Dral and co-workers, are given. The PIP fits are as precise as those using these methods, but the PIP computation time for energy and force evaluation is shown to be 10–1000 times faster. Finally, a new PIP potential energy surface (PES) is reported for ethanol based on a more extensive dataset of energies and gradients than in the MD17 database. Diffusion Monte Carlo calculations that fail on MD17-based PESs are successful using the new PES.
Customizing Web 2.0 tools to writing pedagogy
Authors: Karimi Mohammad Nabi , Asadnia Fatemeh
Published: January 2022

In this study, we explored L2 writing teachers’ professional
development in terms of Web 2.0-mediated writing pedagogy within the
technological pedagogical content knowledge (TPACK) framework. Using
reflective journals and in-depth interviews, we found that in an online L2
writing teacher education course, the writing teachers learned that, for
their instruction to be effective, they need to purposefully design Web
2.0-mediated writing tasks, guide learners’ use of Web 2.0 tools, and
develop collaborative writing procedures for Web 2.0-based task completion.
The participants further highlighted the importance of adaptive L2 writing
instruction/assessment, learner-oriented writing instruction, their
mediatory roles as writing facilitators, selection of Web 2.0 tools for
writing pedagogy, and digital tools as writing e-portfolios.
Cross-jurisdictional linguistic cooperation in multilingual federations
Authors: von Busekist Astrid
Published: January 2022

Political federations or quasi-federations characterised by linguistic diversity have developed various strategies to strike a balance between mobility and inclusion of (internal and external) migrants. This chapter first looks at the comparative performance of linguistic management and coordination between the central state and federal entities, mainly comparing Canada and the US, while exploring possible comparisons with India, in order to provide the EU with examples of language policies in large economic and political unions. We show that the experimental potential of sub-state entities, the cooperation between the public and the private sector, and reciprocity among sub-units are key to achieving linguistic non domination (Section 1). It then suggests mobility and inclusion equilibria via linguistic subsidiarity and reciprocity for the EU (Section 2). It concludes by introducing a new tool, a ‘language passport’ we have called Linguapass (Section 3). The expected benefits of Linguapass on an individual level are to recognise and document the linguistic skills of migrants in official and non-official languages and hence to facilitate their mobility and inclusion; on a collective level, commitment to equal and reciprocal accreditation and funding of Linguapass by the EU as a whole, as well as by European regions and some large existing language clusters, is a novel form of equitable and feasible language cooperation and coordination.
Justifying language policies in mobile societies
Authors: Carey Brian , Shorten Andrew
Published: January 2022

A conception of linguistic justice refers to a set of moral principles that can provide guidance about a society’s language policies. By the lights of a recently prominent strand of liberal political theory, such a conception will be legitimate if and only if it meets certain standards of public justification. Amongst other things, this means that it must be arrived at by way of a legitimate procedure and its principles must be ones that no one could reasonably reject. This chapter explores the potential of this ideal for mobile and multilingual societies in Europe by developing three arguments. First, we argue that in order to be legitimate, a conception of linguistic justice must be justifiable to a relevant constituency and that, in EU member states, this includes mobile Europeans as well as the citizens of member states. Second, we argue that, in circumstances of linguistic diversity, the requirements of public justification generate a presumption in favour of multilingual deliberative procedures. Third, we argue that when selecting principles of justice we ought to prioritise the interests of the least advantaged, and that doing so will often mean that only a multilingual language regime is acceptable.
Language use in international retirement migration
Authors: Gustafson Per , Laksfoss Cardozo Ann Elisabeth
Published: January 2022

Most research on migration and language has examined labour, refugee or family migrants. International retirement migration provides a different perspective on mobility, inclusion and multilingualism. The present chapter examines language use, linguistic challenges and linguistic strategies in the context of retirement migration from Scandinavia to the Alicante province in Spain. Interviews with retired migrants and local key persons showed that retirees often found it difficult to learn the local language, but that a range of other linguistic strategies were available to them. These strategies involved using either their native language or English. Use of the native language occurred in expatriate communities and in settings where interpretation or translation was available. Intercomprehension among retirees speaking different Scandinavian languages was also observed. A final native language strategy was exit – a temporary or in some cases permanent return to the retiree’s (former) home country. The chapter summarises these observations in a typology of linguistic strategies. It also highlights a number of context-specific conditions for these strategies in the case under study – the presence of well-established expatriate communities, the association between retirement migration and tourism, and the widespread use of English as a lingua franca. Given this particular linguistic landscape, Scandinavian retirees were mostly able to manage everyday communication without knowing much Spanish. Serious language-related problems appeared in specific situations, mainly related to health and elderly care, contacts with legal authorities, certain housing-related matters, and emergencies.
Lernaean knots and band surgery
Authors: Belousov Yu. , Karev M. , Malyutin A. , Miller A. , Fominykh E.
Published: January 2022

The paper is devoted to a line of the knot theory related to the conjecture on the additivity of the crossing number for knots under connected sum. A series of weak versions of this conjecture are proved. Many of these versions are formulated in terms of the band surgery graph also called the

H
(
2
)

H(2)

-Gordian graph.
Quaternionic Grassmannians and Borel classes in algebraic geometry
Authors: Panin I. , Walter C.
Published: January 2022

The quaternionic GrassmannianH Gr⁡(r,n)\operatorname {H Gr}(r,n)is the affine open subscheme of the usual Grassmannian parametrizing those2r2r-dimensional subspaces of a2n2n-dimensional symplectic vector space on which the symplectic form is nondegenerate. In particular, we haveHPn=H Gr⁡(1,n+1)\operatorname {HP}^n = \operatorname {H Gr}(1,n+1). For a symplectically oriented cohomology theoryAA, including oriented theories but also the HermitianK\operatorname {K}-theory, Witt groups, and algebraic symplectic cobordism, we have<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper A left-parenthesis upper H upper P Superscript n Baseline right-parenthesis equals upper A left-parenthesis p t right-parenthesis left-bracket p right-bracket slash left-parenthesis p Superscript n plus 1 Baseline right-parenthesis">A(HPn)=A(pt)[p]/(pn+1)A(\operatorname {HP}^n) = A(\operatorname {pt})[p]/(p^{n+1}). Borel classes for symplectic bundles are introduced in the paper. They satisfy the splitting principle and the Cartan sum formula, and they are used to calculate the cohomology of quaternionic Grassmannians. In a symplectically oriented theory the Thom classes of rank22symplectic bundles determine Thom and Borel classes for all symplectic bundles, and the symplectic Thom classes can be recovered from the Borel classes.

The cell structure of theH Gr⁡(r,n)\operatorname {H Gr}(r,n)exists in cohomology, but it is difficult to see more than part of it geometrically. An exception isHPn\operatorname {HP}^nwhere the cell of codimension 2i2iis a quasi-affine quotient ofA4n−2i+1\mathbb {A}^{4n-2i+1}by a nonlinear action ofGa\mathbb {G}_a.
Refashioning the uneasy relationship between older people and geriatric medicine
Authors: O’Neill Desmond
Published: January 2022

A notable feature of most medical specialties is close joint working between patient advocacy groups and specialist societies in furthering improvements in policy and services. While growing old is not a disease, nor too is being a child, and the engagement of advocacy and international bodies such as UNICEF with paediatricians is well established and recognised. Yet almost eight decades after the founding of geriatric medicine, it is clear that this type of relationship does not hold for the advocacy bodies representing those we serve, as well as the wider constituency of older people.

Geriatricians are an extraordinary resourceful and imaginative group, and a more effective promotion of our role as guardians of the longevity dividend is vital to a more positive and mutually beneficial relationship with older people and society. This will require a redirection of our focus to a more critical stance on our origins as a discipline, our relationship with ageing across the lifespan and with older people and a fuller engagement with the broader concepts of gerontology in training and research to develop a refreshed articulacy for, the opportunities arising from gerontologically attuned healthcare.
Characterization of biofilm structure and properties via processing of 2D optical coherence tomography images in BISCAP
Authors: Narciso Diogo A C , Pereira Ana , Dias Nuno O , Melo Luis F , Martins F G
Published: January 2022

Motivation

Processing of Optical Coherence Tomography (OCT) biofilm images is currently restricted to a set of custom-made MATLAB scripts. None of the tools currently available for biofilm image processing (including those developed for Confocal Laser Scanning Microscopy—CLSM) enable a fully automatic processing of 2D OCT images.

Results

A novel software tool entitled Biofilm Imaging and Structure Classification Automatic Processor (BISCAP) is presented. It was developed specifically for the automatic processing of 2D OCT biofilm images. The proposed approach makes use of some of the key principles used in CLSM image processing, and introduces a novel thresholding algorithm and substratum detection strategy. Two complementary pixel continuity checks are executed, enabling very detailed pixel characterizations. BISCAP delivers common structural biofilm parameters and a set of processed images for biofilm analysis. A novel biofilm ‘compaction parameter’ is suggested. The proposed strategy was tested on a set of 300 images with highly satisfactory results obtained. BISCAP is a Python-based standalone application, not requiring any programming knowledge or property licenses, and where all operations are managed via an intuitive Graphical User Interface. The automatic nature of this image processing strategy decreases biasing problems associated to human-perception and allows a reliable comparison of outputs.

Availability and implementation

BISCAP and a collection of biofilm images obtained from OCT scans can be found at: https://github.com/diogonarciso/BISCAP.

Supplementary information

Supplementary data are available at Bioinformatics online.
State-dependent signatures of anti-N-methyl-d-aspartate receptor encephalitis
Authors: von Schwanenflug Nina , Krohn Stephan , Heine Josephine , Paul Friedemann , Prüss Harald , Finke Carsten
Published: January 2022

Traditional static functional connectivity analyses have shown distinct functional network alterations in patients with anti-N-methyl-d-aspartate receptor encephalitis. Here, we use a dynamic functional connectivity approach that increases the temporal resolution of connectivity analyses from minutes to seconds. We hereby explore the spatiotemporal variability of large-scale brain network activity in anti-N-methyl-d-aspartate receptor encephalitis and assess the discriminatory power of functional brain states in a supervised classification approach. We included resting-state functional magnetic resonance imaging data from 57 patients and 61 controls to extract four discrete connectivity states and assess state-wise group differences in functional connectivity, dwell time, transition frequency, fraction time and occurrence rate. Additionally, for each state, logistic regression models with embedded feature selection were trained to predict group status in a leave-one-out cross-validation scheme. Compared to controls, patients exhibited diverging dynamic functional connectivity patterns in three out of four states mainly encompassing the default-mode network and frontal areas. This was accompanied by a characteristic shift in the dwell time pattern and higher volatility of state transitions in patients. Moreover, dynamic functional connectivity measures were associated with disease severity and positive and negative schizophrenia-like symptoms. Predictive power was highest in dynamic functional connectivity models and outperformed static analyses, reaching up to 78.6% classification accuracy. By applying time-resolved analyses, we disentangle state-specific functional connectivity impairments and characteristic changes in temporal dynamics not detected in static analyses, offering new perspectives on the functional reorganization underlying anti-N-methyl-d-aspartate receptor encephalitis. Finally, the correlation of dynamic functional connectivity measures with disease symptoms and severity demonstrates a clinical relevance of spatiotemporal connectivity dynamics in anti-N-methyl-d-aspartate receptor encephalitis.
A case report of severe cardioinhibitory reflex syncope associated with coronavirus disease 2019
Authors: Beil Johannes , Gatti Alessia , Leonhard Bruch , Schroer Hinrich
Published: January 2022

Background

Coronavirus disease 2019 (COVID-19) has been recognized as a disease with a broad spectrum of clinical manifestations. In this report, we illustrate an extraordinary case of severe cardioinhibitory reflex syncope with prolonged asystole associated with COVID-19.

Case summary

A 35-year-old male patient presented to the emergency department with a 10-day history of postural syncope and fever. Electrocardiogram monitoring during positional change revealed reflex syncope with cardioinhibitory response, exhibiting sinus bradycardia, subsequent asystole, and syncope. The patient tested positive for severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) and was admitted to the intensive care unit where temporary transvenous pacing was necessary because of prolonged episodes of asystole. Work-up included extensive cardiac and neurological diagnostic testing, but did not yield any structural abnormalities. Although temporary pacing was able to abort syncope, a decision was made to hold off on permanent pacing as the most likely aetiology was felt to be temporary cardioinhibitory reflex syncope associated with COVID-19. The patient was discharged with mild symptoms of orthostatic intolerance and responded well to education and lifestyle modification. Outpatient follow-up with repeat tilt testing after 3 and 6 months initially showed residual inducible syncope but was eventually normal and the patient remained asymptomatic.

Discussion

We believe that autonomic imbalance with a strong vagal activation due to acute SARS-CoV-2 infection played a pivotal role in the occurrence of transient syncope in this patient’s condition. Although pacemaker implantation would have been a reasonable alternative, a watch-and-wait approach should be considered in similar instances.
Hobo Economicus*
Authors: Leeson Peter T , Hardy R August , Suarez Paola A
Published: January 2022

The central implication of maximising behaviour amid competition is that rates of return tend toward equality. We test that implication in a market whose participants have the traits that behavioural economics suggests should make it hardest to find evidence of maximisation: the market for panhandling at Metrorail stations in Washington, District of Columbia. We find that stations with more panhandling opportunities attract more panhandlers and that cross-station differences in hourly panhandling receipts are statistically indistinguishable from zero. Panhandling rates of return thus tend toward equality. Extreme ‘behavioural’ traits do not prevent maximisation in this market.
Swiss Job Market Monitor: A Rich Source of Demand-Side Micro Data of the Labour Market
Authors: Buchmann Marlis , Buchs Helen , Busch Felix , Clematide Simon , Gnehm Ann-Sophie , Müller Jan
Published: January 2022

The Swiss Job Market Monitor (SJMM) is a data collection of job ads for a national labour market from 1950 onwards. It is a prime example for demonstrating how to turn digital data into a high-quality social science data set. It is also exemplary for combining digital data with historically grown job ads data to provide a comparable time series covering the past 70 years. Paying close attention to sampling procedures, coverage, and key variables, the Data Brief shows how the SJMM profits from opportunities offered by computational social science and computational linguistics to navigate a wholly new set of challenges involved in creating such a data set. It closes with a discussion of new research opportunities this data set is opening for investigating the labour market as a core institution of modern society.
The effectiveness of mindfulness-based stress reduction for school teachers: a cluster-randomized controlled trial
Authors: Bonde Emilie H , Fjorback Lone O , Frydenberg Morten , Juul Lise
Published: January 2022

Background

Teaching has been found to be one of the most stressful occupations. Hence, current interest in reducing stress and enhancing the well-being of teachers is strong. Mindfulness-based stress reduction (MBSR) is documented to be effective in reducing stress and increasing well-being. This study investigated the effectiveness of delivering MBSR to lower secondary school teachers as a part of a teacher-training programme.

Methods

This study was a nested trial within the parallel cluster-randomized controlled trial, Stress-free Everyday LiFe for Children and Adolescents REsearch (SELFCARE). Schools were recruited from all five geographical regions in Denmark between May 2018 and May 2019. One to three teachers from each school were allowed to participate. At baseline, 110 schools, representing 191 lower secondary school teachers, were cluster-randomized to intervention or a wait-list control group. The intervention group received MBSR during 2019 and the wait-list control group during 2020. Data were collected at baseline and after 3  and 6 months. The primary outcome was measured by Cohen’s Perceived Stress Scale (PSS). Data were analyzed using a mixed-effect linear regression model and bootstrapped for cluster effects.

Results

At 3 months, the intervention group statistically significantly reduced their PSS score 1.7 [95% confidence interval (CI) 0.04–3.3] points more than did the wait-list control group. At 6 months, the intervention group had statistically significantly reduced their mean PSS score 2.1 (95% CI: 0.5–3.8) points more than the wait-list control group.

Conclusion

It is possible to reduce perceived stress among lower secondary school teachers by delivering MBSR as part of a teacher-training programme.
A nonfunctional copy of the salmonid sex-determining gene (sdY) is responsible for the “apparent” XY females in Chinook salmon, Oncorhynchus tshawytscha
Authors: Bertho Sylvain , Herpin Amaury , Jouanno Elodie , Yano Ayaka , Bobe Julien , Parrinello Hugues , Journot Laurent , Guyomard René , Muller Thomas , Swanson Penny , McKinney Garrett , Williamson Kevin , Meek Mariah , Schartl Manfred , Guiguen Yann
Published: January 2022

Many salmonids have a male heterogametic (XX/XY) sex determination system, and they are supposed to have a conserved master sex-determining gene (sdY) that interacts at the protein level with Foxl2 leading to the blockage of the synergistic induction of Foxl2 and Nr5a1 of the cyp19a1a promoter. However, this hypothesis of a conserved master sex-determining role of sdY in salmonids is challenged by a few exceptions, one of them being the presence of naturally occurring “apparent” XY Chinook salmon, Oncorhynchus tshawytscha, females. Here, we show that some XY Chinook salmon females have a sdY gene (sdY-N183), with 1 missense mutation leading to a substitution of a conserved isoleucine to an asparagine (I183N). In contrast, Chinook salmon males have both a nonmutated sdY-I183 gene and the missense mutation sdY-N183 gene. The 3-dimensional model of SdY-I183N predicts that the I183N hydrophobic to hydrophilic amino acid change leads to a modification in the SdY β-sandwich structure. Using in vitro cell transfection assays, we found that SdY-I183N, like the wild-type SdY, is preferentially localized in the cytoplasm. However, compared to wild-type SdY, SdY-I183N is more prone to degradation, its nuclear translocation by Foxl2 is reduced, and SdY-I183N is unable to significantly repress the synergistic Foxl2/Nr5a1 induction of the cyp19a1a promoter. Altogether, our results suggest that the sdY-N183 gene of XY Chinook females is nonfunctional and that SdY-I183N is no longer able to promote testicular differentiation by impairing the synthesis of estrogens in the early differentiating gonads of wild Chinook salmon XY females.
New insights into the regulatory roles of glutathione in NLRP3-inflammasome-mediated immune and inflammatory responses
Authors: Zhang Tianli , Tsutsuki Hiroyasu , Li Xiaoyan , Sawa Tomohiro
Published: January 2022

Glutathione (GSH) is the most abundant non-protein thiol (-SH) in mammalian cells. Its synthesis and metabolism serve to maintain cellular reduction–oxidation (redox) homeostasis, which is important for multiple cellular processes including proliferation, differentiation and death. An accumulating body of evidence suggests that the essential roles of GSH extended far beyond its oxidant and electrophile scavenger activities and regulatory role in the lifespan of cells. Recent findings revealed that altered GSH levels are closely associated with a wide range of pathologies including bacterial and viral infections, neurodegenerative diseases and autoimmune disorders, all of which are also characterized by aberrant activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome. As a result of these findings, GSH was assigned a central role in influencing the activation of the NLRP3 inflammasome. To expand on our recent advances in understanding this process, we discuss here the emerging roles of GSH in activation of the NLRP3 inflammasome, and the therapeutic potential of GSH in its associated pathologies.
Planning and Professional Assistance as Factors Influencing Private Forest Landowner Best Management Practice Implementation
Authors: Wilson David C , Kilgore Michael A , Snyder Stephanie A
Published: January 2022

Virtually all states have developed best management practices (BMPs) to mitigate potential adverse effects associated with timber harvesting. This study examined how BMP implementation on Minnesota’s family forest lands varied according to whether the land had a forest management plan, the timber sale was administered by a forester, or a written timber harvesting contract was used. Analysis of field monitoring data from 174 commercial timber harvesting sites on family forest lands found that BMP implementation is only modestly influenced by a forest management plan, supervising forester, or timber harvesting contract. Supervision of a forester had the greatest influence, with six guidelines implemented differently. In contrast, differences were found for just two BMPs with a forest management plan and only one with a written timber harvesting contract. When timber sales were administered by a forester, forest management guidelines generally related to management of the land-water interface were implemented to a higher standard, with significant increases observed for avoidance of infrastructure in filter strips, use of water diversion and erosion control structures, avoiding unnecessary wetland and waterbody crossings, and slash management. Higher timber utilization efficiency (within leave tree guidelines) was also found when a professional forester supervised the timber sale.

Study Implications: We examine how BMP implementation on family forest lands varies with three types of supervisory and planning assistance: a forest management plan for the property, sale administration by a professional forester, and a written timber harvesting contract. Field monitoring data from 174 commercial timber harvests on family forest lands indicate that BMP implementation is only modestly influenced by any single form of assistance. Supervision by a forester had the greatest influence, increasing use of four guidelines related to management of the land-water interface. Results may help to inform best practices for landowner assistance and planning.
An evolutionary channel for CO-rich and pulsating He-rich subdwarfs
Authors: Miller Bertolami M M , Battich T , Córsico A H , Althaus L G , Wachlin F C
Published: January 2022

Recently, a new class of hot subluminous stars strongly enriched in C and O has been discovered (CO-sdOs). These stars show abundances very similar to those observed in PG1159 stars but at lower temperatures. Moreover, it has been recently suggested that C and O enrichment might be the key ingredient driving the pulsations in He-rich hot subdwarf stars (He-sdBVs). Here, we argue that these two types of rare stars can be explained by a variant of one of the main channels forming hot subdwarf stars. The scenario involves the formation and merging of a He-core white dwarf and a less massive CO-core white dwarf. We have constructed simple merger models and computed their subsequent evolution. The merger products are in agreement with the surface parameters and composition of CO-sdOs. In addition, we have performed simulations including the effects of element diffusion and the excitation of pulsations. These simulations show that less massive merger products can form stellar structures that have surface parameters, abundances, and pulsation periods similar to those displayed by He-sdBVs. We conclude that the proposed scenario, or some variant of it, offers a very plausible explanation for the formation of CO-sdOs, pulsating He-sdBs, and low-luminosity PG1159 stars.