bluuebunny/crossref_metadata_2025 huggingface dataset:
Methodology for processing expert judgments based on fuzzy weighted summation
Authors: Sudakov V , Sivakova T
Published: September 2020

The paper is devoted to the development and research of a new technique for fuzzy ranking of alternatives. The authors of this approach suggest dividing the criteria space into fuzzy preference areas. A criterion for the proximity of fuzzy preference ratings is also formulated. The scientific novelty of the proposed approach lies in the proposed procedure for clarifying the level of preference based on fuzzy weighted summation, for alternatives with close fuzzy levels of preference. The solution of the problem in this statement makes it possible to increase the distinguishability of alternatives by preference. Two approaches to the construction of membership functions of fuzzy preferences were investigated: the first method - choosing the type of membership function and then entering the parameters of the membership function; the second method is entering the characteristic points of the membership function and constructing a piecewise polynomial approximation. After entering preferences and presetting, this method allows ranking an arbitrary number of alternatives in a mode close to real time. In cases of high dimensionality of the vector criterion and optimized parameters of the domain model, as well as in the presence of complex algorithmic rules, the solution of such problems is of high scientific importance. In the public domain at http://ws-dss.com one can use this method - fuzzy ranking based on preference areas. The proposed approach was implemented (tested) on the problem of selecting an electronic pilot tablet.
Structure of a viscoplastic fluid flow in a pipe with a given obstruction shape
Authors: Ryltsev I , Shrager G
Published: September 2020

In this paper, we present a study of the axisymmetric steady-state laminar flow of a viscoplastic fluid in a pipe with variable cross section. Mathematical formulation of the problem is written in terms of stream function and vorticity variables in a cylindrical coordinate system. Rheological behavior of the medium is described by the Shvedov-Bingham model. Coordinate transformation is carried out to implement a numerical algorithm. The problem is solved numerically using the finite-difference method and the false transient method. This paper demonstrates the effect of Reynolds number, Bingham number, and geometric parameters of a flow domain on the flow structure.
Stability of the flow with an over-compressed detonation wave in a duct of variable cross section
Authors: Egoryan A J , Valiyev Kh F
Published: September 2020

The stability of stationary flows of an ideal gas in ducts of variable cross section with an over-compressed detonation wave is studied. The combustible mixture before the wave and the combustion products after it are perfect gases. A numerical-analytical method has been developed to analyse the stability of stationary flows with over-compressed detonation waves. The calculations performed, demonstrating its effectiveness, revealed examples of stable flows with over-compressed detonation wave in ducts of variable cross section.
Hierarchical database management model with uncertain parameters
Authors: Korotkova T I , Mokhov A A
Published: September 2020

Decision making in large technical, biological, economic and other systems always requires the creation of a complex information system. This implies the need to create sophisticated software for the safe storage of information, its updating and management. At the same time, there should be a convenient and easy to use interface that provides the user with all the necessary functions without unnecessary actions. In conditions of uncertainty, the volume of information becomes even greater. A central coordination system must exist to avoid data inconsistencies and redundancies and to increase the reliability of information storage in the database management system (DBMS). In this article, we propose using a database with a hierarchical structure. In such databases, it is possible to quickly update information at each level separately, without accumulating excessive amounts of information for the entire system.
Improvement of the Landau-Teller model for CO2 on the basis of the Chapman–Enskog method
Authors: Kustova E , Lukasheva A , Mekhonoshina M
Published: September 2020

Vibrational relaxation of carbon dioxide in the three-temperature kinetic-theory approach is studied. The focus is on the evaluation of the vibrational energy production terms in the coupled symmetric-bending and asymmetric modes. Using the generalized Chapman – Enskog method, the energy production terms are expressed as functions of the gas temperature, vibrational temperatures of CO2 modes and probabilities of corresponding transitions. It is shown that a modification of the Landau–Teller formula can be obtained from the rigorous theoretical expressions using several limiting assumptions. Whereas VT relaxation in the bending mode can be described by the Landau–Teller approximation with a satisfactory accuracy, its application to the inter-mode exchange requires introducing relaxation times depending on the vibrational temperatures of the modes involved to the transitions.
The influence of chemical reaction models on shock heated flow parameters in CO2/CO/O2/O/C mixture
Authors: Kosareva A , Nagnibeda E , Savelev A
Published: September 2020

In the present paper non-equilibrium flows of CO2/CO/O2/O/C mixture behind shock waves is studied taking into account vibrational excitation of CO2, CO, O2 molecules. The kinetic scheme includes vibrational energy transitions, dissociation, recombination and exchange chemical reactions. The problem is solved in the five-temperature kinetic theory approximation. The equations for vibrational temperatures of symmetric–bending and asymmetric CO2 modes and for diatomic species are coupled to the gas dynamic equations and applied to study flow parameters in the relaxation zone behind shock waves. Different models for one-temperature and multi-temperature rates of chemical reactions are used in calculations and the influence of exchange reactions and reaction models on flow parameters in the relaxation zone behind the shock wave is studied in the paper.
Effect of aspect ratio and end plates on rotational oscillations of thick plates in air flow
Authors: Shmigirilov R V , Ryabinin A N
Published: September 2020

The steady oscillations of elastically fixed thick plates in the air flow are considered. The oscillation amplitudes are measured using the strain gauge method. In experiments, the aspect ratio varies. Some of the experiments were performed with end plates. Steady-state oscillation amplitude increases with an increase in plate aspect ratio. In the presence of end plates, the oscillation amplitude linearly depends on the Strouhal number. Increasing the aspect ratio of the thick plate from 5 to 7 does not lead to a significant change in the amplitude of oscillations.
On the formation of a vortex couple in fluid
Authors: Gushchin V A , Smirnova I A
Published: September 2020

The task of forming a vortex couple in a homogeneous non-viscous fluid is investigated numerically. One of the latest variants of the Splitting Method for Incompressible Fluid (SMIF) developed by the authors is used to solve the problem. The finite difference scheme of the method has the following properties: the second order of approximation on spatial variables, minimal scheme viscosity and dispersion, monotony. It is shown that vortex couple is formed only at relatively short distances between the centers of vortexes. As this distance increases, the couple is formed longer in time. In the future, it is planned to take into account the impact of viscosity on this formation.
Issues of controlling the motion of a space object by the impact of the ion beam
Authors: Kulkov V M , Markin N N , Egorov Yu G
Published: September 2020

The problem of controlling the trajectory motion of space objects (SO) using particle beams interacting with the surface of the SO is considered. The source of high-energy particles can be an ion thruster mounted on board a spacecraft (SC). To evaluate the control forces, a model is presented that reflects the mechanism of interaction of the ion beam with the surface of the SO. The motion control for the center of mass of the “SC - SO” system is provided due to the thrust vectoring capability of the service spacecraft electric propulsion system (EPS). Mutual motion control of the SC and SO is ensured by controlling the position of the service spacecraft relative to the SO in the orbital coordinate system. In this paper, expressions for an asymptotically stable control process ensuring the transportation of SO with the specified characteristics are derived.
Study of the low-power krypton-operated stationary plasma thruster plume
Authors: Kim V P , Merkurev D V , Shilov E A , Zakharchenko V S , Kalyazin V G
Published: September 2020

The paper presents the results of experimental studies of the plume of low power stationary plasma thruster SPT-40 model, operating with krypton at discharge power of about 250 W, and with xenon at discharge power of about 200 W. A comparative analysis of the SPT -40 model plume characteristics was carried out that revealed significant differences in the distributions of current density of accelerated ions in the angle of deviation of the measurement directions from the thruster axis and in the distributions of average ion energies in the plume when operating with the above propellants. The flow parameters were measured by a multigrid probe – the retarding potential analyzer (RPA). This devise moved along the semicircular trajectory in a plane that included the thruster axis. The distance from the thruster exit plane to the RPA was equal to 6-7 outer diameters of the thruster-accelerating channel; at such distance, we can consider the thruster as a point source. The measurements were carried out at different operating modes in the propellant consumption and discharge voltage, and it is shown that during the SPT-40 model operation with xenon and krypton the half-angle of the plume divergence was about 70 degrees in the discharge voltage range 150-200 V and it decreased with the discharge voltage growth.
Biharmonic spline interpolation of spatial dose rate distribution in the minimum dose trajectory optimization problem
Authors: Starchenko A E
Published: September 2020

In this paper issues relating to geostationary orbit (GEO) insertion trajectory optimization is considered. The article discusses the GEO transfer trajectory optimization for a spacecraft with an electric propulsion (EP) system with the purpose of reduction of ionizing radiation dose absorbed by onboard systems from the Earth’s radiation belts. The considering trajectory optimization technique is based on the Pontryagin’s maximum principle and the method of numerical continuation. Much attention is paid to smooth approximation of the dose rate dependence on spatial coordinates using biharmonic splines interpolation. The proposed method makes it possible to abandon the methodological simplification of averaging the radiation dose rate over circular orbits to effectively solve this class of problems and directly consider the dependence of the dose rate on time and geographical longitude. Using as an example the minimum time problem for a test transfer, the errors in calculating the dose at the end of the transfer both by the proposed method and by the method of averaging over circular orbits are estimated. The proposed method turned out to be more than 13 times more accurate than the analogue. It can be applied in transfer trajectory optimization problems of an EP spacecraft in order to minimize the total accumulated ionizing radiation dose.
The use of CFD calculations for the solution of the control problem of applying protective coatings of varying thickness
Authors: Borisov S A , Glukhovskaya Ju I , Dobrovolskiy S V , Podporin I V
Published: September 2020

The paper analyzes the results of simulation of a supersonic air flow about simple 3D forms in order to use them for applying protective coatings to the surface with varying thickness by means of cold gas-dynamic spaying. To calculate the results, an aerodynamic analysis is performed in SolidWorks Flow Simulation software environment. Air flow zones on a streamlined surface with various characteristics (pressure, temperature, geometric shape, etc.) are analyzed, and possible methods of determination the boundaries of these zones are considered. For the solution of the control problem of applying protective coatings of varying thickness, the displacement behaviour of the movable nozzle with a small cross section is considered.
On solving the warehouse procession optimization problem using a tuple of heuristics
Authors: Gainanov D N , Korablev I G , Rasskazova V A
Published: September 2020

The paper is a review of the present-day problem about the logistic optimization of both two-dimensional and three-dimensional warehouses with m cranes. A tuple of heuristic algorithms is proposed to solve the NP-hard problem with minimizing the total execution time of a set of jobs using m cranes. The described optimization approaches are applicable to both two- and three-dimensional warehouses. As part of the numerical results, results regarding the solution of applied problems are shown. The ability to train the proposed model allows one to select the best heuristic settings for a specific warehouse based on real world data sets. Another important feature of the model is the ability to distribute the power and parallel execution of three independent processes: the ant colony optimization algorithm to construct a successful sequence of jobs, the algorithm to search the optimal set of heuristic weights of ki
, and the algorithm to solve the planning problem.
H-infinity approach to design optimal output control for the aggregated interpolation model of helicopter motion
Authors: Kudryavtseva I , Efremov A , Panteleev A
Published: September 2020

This paper presents the problem of designing a feedback control of the aggregated model describing helicopter flight dynamics under the influence of exogenous factors based on the H-infinity approach. The original nonlinear equations of dynamics are assumed to be linearized regarding to several flight modes that characterize with a set of precisely specified flight conditions such as an attitude of an aircraft, its forward speed and turn rate. Matrices of the linearized systems are dependent on the speed of the aircraft. Due to that the aggregated model comprises eight submodels corresponding to flight modes when the speed varies from hover to 140 kts in a certain regular interval. The proposed principle of designing includes two stages: on the first stage the feedback control input is selected for each submodel separately so that the H-infinity norm of the value functional with respect to the H-infinity norm of disturbances is minimum; on the second one the interpolation technique lying in the expansion of matrices in the basis of finite functions is applied. The solution method is experienced on three helicopter models: ZD559-Lynx, the twin engine, utility helicopter in the 4.5 -ton category; S123-Bo105, the twin engine helicopter in the 2.5 ton class; SA330-Puma, the twin engine, medium-support helicopter in the 6-ton category.
Use of fuzzy areas of preference in tasks of multi – criteria evaluation of freight air transport
Authors: Sudakov V , Sivakova T
Published: September 2020

This paper shows how, based on the theory of fuzzy sets, the problem of multi-criteria selection of cargo planes is solved. It is proposed to determine fuzzy preference intervals on the scales of aircraft efficiency criteria. At the same time it is allowed to intersect such intervals taking into account the limitations on the maximum and minimum degree of belonging of criterion values. For combinations of fuzzy intervals, Decision Maker makes its judgments on a fuzzy preference scale. The resulting aircraft efficiency model is checked for coverage of all points of the criterion space with a level of preference not lower than the specified one. This model can be used to estimate any number of cargo aircraft in automatic mode. Both clear and fuzzy criterion values can be submitted to the model input, and then the method allows to build the functions of aircraft belonging to all areas of preference. The software implementation of this model can be used to make decisions about the purchase, manufacture, repair of certain types of aircraft and to determine which types of aircraft should be decommissioned.
Analyzing models of air equilibrium composition calculation
Authors: Emelyanov V N , Karpenko A G , Tolstoguzov S S , Volkov K N
Published: September 2020

The atmospheric composition behind a normal shock ahead of a hypersonic vehicle differs from the atmosphere ahead of the shock. Various models of air equilibrium composition are compared, analysis of areas of these models applicability is performed. Numerical simulations of flow in a channel with a step are performed using models of perfect gas and high-temperature air. The results computed with both models are compared.
Studying the applicability of a pulsed magnetic field to biological tissues
Authors: Podolskaya N , Kovalev K , Popov V
Published: September 2020

In biomedicine, there are still a number of issues to be solved and studied. One of them is the treatment of cancer and the problem of gene modification by a non-invasive method. The authors propose a method of using a magnetic field (MF) to solve these issues, in particular, the use of magnetic field strength and eddy currents when exposed to biological tissue. The article describes the mathematical calculations and an experiment model necessary to consider the reactions of healthy and cancer cells to MF. The article highlights prospects for the development of this area.
The strength tests of thin-walled composite shells under non-stationary loads of different physical nature
Authors: Ostrik A V , Bakulin V N , Nikolaev D N
Published: September 2020

Mechanical action of energy fluxes of different physical nature is proposed to be simulated by one-side non-stationary loading. A set of gas-dynamic devices for generation of loads of the required space-time distribution is described. Two new explosive devices for formation of low-impulse loads of microsecond duration are proposed. The methods to measure the parameters of thin-walled composite constructions under dynamic and pulse loads are considered. Time deformation profiles of fiberglass cylindrical shell under low-impulse load of microsecond duration are given. The use of wire or foil sensors for the measurement of deformations gives close results when investigating the shell stage of deformation of fiberglass thin-walled constructions.
How to reduce the probability of erroneous decisions in the systems of collective intelligence
Authors: Protasov V , Potapova Z , Akhobadze G
Published: September 2020

This work discusses and solves the methodological problem of reducing the probability of erroneous decisions when solving local problems by groups of intelligent agents. Intellectual agents can be carriers of both natural and artificial intelligence. The basic method of the new information technology is based on the theory of evolutionary decision reconciliation developed by the authors. The method is built on the original use of genetic algorithms in which intelligent agents perform the fitness function based on their knowledge and skills. The technology is based on the knowledge model proposed during the work, the Rasch model, and the mathematical apparatus of the Condorcet theorem. A theorem that allows finding the conditions under which the probability of an erroneous solution tends to zero, is formulated and proved. The results of using the theory for objects recognition from images by a group of neural networks are presented. A significant decrease in the probability of errors of the first kind is obtained in comparison with the classical methods. It is proposed to use the technology of evolutionary decision reconciliation to solve local problems in medical diagnostics, banking, and other fields.
Distributed computing based on Container-component model
Authors: Semenov A
Published: September 2020

Cloud computing focuses on scalability, elasticity, and cost-efficiency of the service. In this context, shifting towards the concept of “algorithm as a service” is a contemporary issue. The three main drivers of it includes, machine learning, artificial intelligence, and Digital Earth. The following assumption was made throughout the article, that algorithm as a service is endowed with a key property of fractal, which provides the corresponding scalability and elasticity. The article focuses on the design of elastic algorithms based on Container-component simulation model. The model has fractal property. The application of the model to design gradient ascent algorithm as a service is presented.
Influence of the angular momentum on definition of pressure
Authors: Prozorova E
Published: September 2020

The paper studies the impact of angular momentum in aerodynamic on the problem of flowing liquid near the surface. In a modified theory, the laws of conservation in integral form remain the same, but the divergent and rotational components are not separate. In this theory, the order of different equations is increased. The correspondence between the potential flow with velocity circulation, Newton law and Euler equations with different values of pressure on coordinate axis are discussed for potential flow. As an example of the influence of the angular momentum, the problem of fluid motion between two closely spaced parallel plates is considered.
Research of a two-phase steam system during its flow in the pipe and a device for measuring dryness steam
Authors: Kaplan B Y , Motorin A A , Stupitsky E L
Published: September 2020

Water steam is widely applied in various fields of industry and heat power engineering. The article shows a wide application of water steam in heat-and-power engineering. In this regard, the issue of preserving and controlling the dryness of steam during its transportation via steam lines remains relevant. Quite detailed theoretical studies of steam parameters during its flow in the pipe have been performed. A comparative analysis of steam velocity and temperature plots depending on certain flow parameters and accepted approximations is performed. The analysis presented that gas-dynamic and thermodynamic processes can be considered approximately. This does not play a fundamental role in the general patterns of dropping liquid. As a result of numerical studies of the steam condensation kinetics, the specific volume and density of drop condensate along the pipe section are determined. The obtained results and the proposed methodological approach for determining the parameters of steam were used in the development and further improvement of the device for measuring the dryness of steam, the original construction of which was proposed earlier by one of the authors. The article presents the functional diagram and layout of the measuring unit of the gauge.
Multiple antenna gyro-GNSS attitude determination system
Authors: Zharkov M V , Veremeenko K K , Kuznetsov I M , Pronkin A N
Published: September 2020

Attitude determination system is one of the most important system to control the moving object of any type. GNSS attitude determination systems have been actively developed in the last decade. Such systems have obvious drawbacks associated with the need for the visibility of a sufficient number of satellites. GNSS/Inertial integration is the best way to reduce satellite visibility dependence. The new concept of multiple antenna integrated inertial-satellite system design is proposed. System structure allows to exclude accelerometers from inertial measurement unit replacing it with gyro unit only. An important feature of the system is the availability of the initialization mode in motion and in conditions of limited satellite visibility. System performance was estimated in simulation and car test.
Spectral method for solving linear Caputo fractional stochastic differential equations
Authors: Rybakov K , Yushchenko A
Published: September 2020

We concern on the problem of finding the solution to the linear Caputo fractional stochastic differential equation with additive and multiplicative noise. It is proposed to apply the spectral method based on the spectral form of mathematical description. This method provides both an explicit form of the solution as the orthogonal series with random coefficients and a continuous-time approximation of this solution as the partial sum. Earlier, the spectral method has been applied for solving linear (non-fractional) stochastic differential equations. The proposed method is demonstrated on the modeling fractional Ornstein– Uhlenbeck process described by a linear Caputo fractional stochastic differential equation with additive noise.
Application of Walsh series to represent iterated Stratonovich stochastic integrals
Authors: Rybakov K
Published: September 2020

The goal of the paper is to represent iterated Stratonovich stochastic integrals using orthonormal expansions of functions by the Walsh series, to construct an algorithm for modeling iterated Stratonovich stochastic integrals, and to test this algorithm by numerical experiments. Obtained results may be used in the constructing high-order numerical methods based on the Taylor –Stratonovich expansion and the Taylor– It^o expansion. Therefore, they can be applied in a lot of problems of physics, engineering, economics and finance, when it is necessary to solve numerically stochastic differential equations.
The possibility of draining the boundary layer from the hypersonic nozzle
Authors: Ruleva L B , Solodovnikov S I
Published: September 2020

Hypersonic aerodynamic shock tube is used for comparison (validation) of the developed computer codes for the calculation of aerothermodynamics. Experiments in vacuum chamber of hypersonic aerodynamic shock tube showed the significant boundary layer in the nozzle. An increase in the boundary layer was observed with an increase in the length of the inner surface of the nozzle. Easy method to decrease the boundary layer of the nozzle was suggested. Areas of pressure field near hypersonic nozzle with a reduced pressure in the moment of quasi-stationary flow from the nozzle were determined experimentally.
Increasing hypersonic aerodynamic shock tube working time duration
Authors: Panasenko A V , Ruleva L B , Solodovnikov S I
Published: September 2020

Longer working time of the hypersonic aerodynamic shock tube has been demonstrated by applying modelling and experiment. This facility is a short-term installation. It is used to validate the results of aerothermodynamic characteristics of aircraft modelling calculated using national computational codes. Numerical modeling and experimental data results are compared. Quasi-stationary state of the gas flow in operating time of the installation requires sufficient time. A review of publications about increasing the working time of shock tubes for initiation of high-speed gas flows was made. Some models of shock tubes with longer working time have been selected for discussion. The computational studies for hypersonic aerodynamic shock tube showed a positive trend for one of the operating modes. A simulation for a regular and lengthened shock tube facilities was carried out, taking the flow as in viscous medium and using Euler equations. The effectiveness of lengthening the low pressure channel section of the facility was shown by modelling. The low pressure chamber was elongated by 3m to the existing hypersonic aerodynamic shock tube.
Heat flow measurements on high-speed aircraft models
Authors: Ruleva L B , Solodovnikov S I
Published: September 2020

The functionality of “Hypersonic aerodynamic shock tube” facility was expanded to obtain more complete validation of developed computer codes for the prospective high-speed aircraft aerothermodynamics description. The method of luminescent temperature converters was applied in the laboratory installation. Measuring of temperature fields on the surface of models installed in the aerodynamic unit when they have ambient air flow at Mach numbers M=5-7, have been implemented. The calorimetric type heat flow sensor was selected among existing heat flow sensors as it based on microsecond inertia, miniaturization, and relative ease of manufacturing. The sensitive elements of the calorimetric sensors were manufactured for the laboratory installation. The ability of the manufactured sensors to work and the dependence of the response time from the thickness of the heat-receiving surface were revealed.
Probable delirium is a presenting symptom of COVID-19 in frail, older adults: a cohort study of 322 hospitalised and 535 community-based older adults
Authors: Zazzara Maria Beatrice , Penfold Rose S , Roberts Amy L , Lee Karla A , Dooley Hannah , Sudre Carole H , Welch Carly , Bowyer Ruth C E , Visconti Alessia , Mangino Massimo , Freidin Maxim B , El-Sayed Moustafa Julia S , Small Kerrin S , Murray Benjamin , Modat Marc , Graham Mark S , Wolf Jonathan , Ourselin Sebastien , Martin Finbarr C , Steves Claire J , Lochlainn Mary Ni
Published: September 2020

Background

Frailty, increased vulnerability to physiological stressors, is associated with adverse outcomes. COVID-19 exhibits a more severe disease course in older, comorbid adults. Awareness of atypical presentations is critical to facilitate early identification.

Objective

To assess how frailty affects presenting COVID-19 symptoms in older adults.

Design

Observational cohort study of hospitalised older patients and self-report data for community-based older adults.

Setting

Admissions to St Thomas’ Hospital, London with laboratory-confirmed COVID-19. Community-based data for older adults using the COVID Symptom Study mobile application.

Subjects

Hospital cohort: patients aged 65 and over (n = 322); unscheduled hospital admission between 1 March 2020 and 5 May 2020; COVID-19 confirmed by RT-PCR of nasopharyngeal swab. Community-based cohort: participants aged 65 and over enrolled in the COVID Symptom Study (n = 535); reported test-positive for COVID-19 from 24 March (application launch) to 8 May 2020.

Methods

Multivariable logistic regression analysis performed on age-matched samples from hospital and community-based cohorts to ascertain association of frailty with symptoms of confirmed COVID-19.

Results

Hospital cohort: significantly higher prevalence of probable delirium in the frail sample, with no difference in fever or cough. Community-based cohort: significantly higher prevalence of possible delirium in frailer, older adults and fatigue and shortness of breath.

Conclusions

This is the first study demonstrating higher prevalence of probable delirium as a COVID-19 symptom in older adults with frailty compared to other older adults. This emphasises need for systematic frailty assessment and screening for delirium in acutely ill older patients in hospital and community settings. Clinicians should suspect COVID-19 in frail adults with delirium.
Composite grid designs for adaptive computer experiments with fast inference
Authors: Plumlee M , Erickson C B , Ankenman B E , Lawrence E
Published: September 2020

Experiments are often used to produce emulators of deterministic computer code. This article introduces composite grid experimental designs and a sequential method for building the designs for accurate emulation. Computational methods are developed that enable fast and exact Gaussian process inference even with large sample sizes. We demonstrate that the proposed approach can produce emulators that are orders of magnitude more accurate than current approximations at a comparable computational cost.
Chronic stress induces significant gene expression changes in the prefrontal cortex alongside alterations in adult hippocampal neurogenesis
Authors: Musaelyan Ksenia , Yildizoglu Selin , Bozeman James , Du Preez Andrea , Egeland Martin , Zunszain Patricia A , Pariante Carmine M , Fernandes Cathy , Thuret Sandrine
Published: September 2020

Adult hippocampal neurogenesis is involved in stress-related disorders such as depression, posttraumatic stress disorders, as well as in the mechanism of antidepressant effects. However, the molecular mechanisms involved in these associations remain to be fully explored. In this study, unpredictable chronic mild stress in mice resulted in a deficit in neuronal dendritic tree development and neuroblast migration in the hippocampal neurogenic niche. To investigate molecular pathways underlying neurogenesis alteration, genome-wide gene expression changes were assessed in the prefrontal cortex, hippocampus and the hypothalamus alongside neurogenesis changes. Cluster analysis showed that the transcriptomic signature of chronic stress is much more prominent in the prefrontal cortex compared to the hippocampus and the hypothalamus. Pathway analyses suggested huntingtin, leptin, myelin regulatory factor, methyl-CpG binding protein and brain-derived neurotrophic factor as the top predicted upstream regulators of transcriptomic changes in the prefrontal cortex. Involvement of the satiety regulating pathways (leptin) was corroborated by behavioural data showing increased food reward motivation in stressed mice. Behavioural and gene expression data also suggested circadian rhythm disruption and activation of circadian clock genes such as Period 2. Interestingly, most of these pathways have been previously shown to be involved in the regulation of adult hippocampal neurogenesis. It is possible that activation of these pathways in the prefrontal cortex by chronic stress indirectly affects neuronal differentiation and migration in the hippocampal neurogenic niche via reciprocal connections between the two brain areas.
Variants inPPP2R2BandIGF2BP3are associated with higher tau deposition
Authors: Ramanan Vijay K , Wang Xuewei , Przybelski Scott A , Raghavan Sheelakumari , Heckman Michael G , Batzler Anthony , Kosel Matthew L , Hohman Timothy J , Knopman David S , Graff-Radford Jonathan , Lowe Val J , Mielke Michelle M , Jack Clifford R , Petersen Ronald C , Ross Owen A , Vemuri Prashanthi
Published: September 2020

Tau deposition is a key biological feature of Alzheimer’s disease that is closely related to cognitive impairment. However, it remains poorly understood why certain individuals may be more susceptible to tau deposition while others are more resistant. The recent availability of in vivo assessment of tau burden through positron emission tomography provides an opportunity to test the hypothesis that common genetic variants may influence tau deposition. We performed a genome-wide association study of tau-positron emission tomography on a sample of 754 individuals over age 50 (mean age 72.4 years, 54.6% men, 87.6% cognitively unimpaired) from the population-based Mayo Clinic Study of Aging. Linear regression was performed to test nucleotide polymorphism associations with AV-1451 (18F-flortaucipir) tau-positron emission tomography burden in an Alzheimer’s-signature composite region of interest, using an additive genetic model and covarying for age, sex and genetic principal components. Genome-wide significant associations with higher tau were identified for rs76752255 (P = 9.91 × 10−9, β = 0.20) in the tau phosphorylation regulatory gene PPP2R2B (protein phosphatase 2 regulatory subunit B) and for rs117402302 (P  = 4.00 × 10−8, β = 0.19) near IGF2BP3 (insulin-like growth factor 2 mRNA-binding protein 3). The PPP2R2B association remained genome-wide significant after additionally covarying for global amyloid burden and cerebrovascular disease risk, while the IGF2BP3 association was partially attenuated after accounting for amyloid load. In addition to these discoveries, three single nucleotide polymorphisms within MAPT (microtubule-associated protein tau) displayed nominal associations with tau-positron emission tomography burden, and the association of the APOE (apolipoprotein E) ɛ4 allele with tau-positron emission tomography was marginally nonsignificant (P  = 0.06, β = 0.07). No associations with tau-positron emission tomography burden were identified for other single nucleotide polymorphisms associated with Alzheimer’s disease clinical diagnosis in prior large case–control studies. Our findings nominate PPP2R2B and IGF2BP3 as novel potential influences on tau pathology which warrant further functional characterization. Our data are also supportive of previous literature on the associations of MAPT genetic variation with tau, and more broadly supports the inference that tau accumulation may have a genetic architecture distinct from known Alzheimer’s susceptibility genes, which may have implications for improved risk stratification and therapeutic targeting.
Persistence of Racial Inequities in Receipt of Influenza Vaccination Among Nursing Home Residents in the United States
Authors: Bardenheier Barbara H , Baier Rosa R , Silva Joe B , Gravenstein Stefan , Moyo Patience , Bosco Elliott , Ogarek Jessica , van Aalst Robertus , Chit Ayman , Loiacono Matthew , Zullo Andrew R
Published: September 2020

Background

We sought to determine if racial differences in influenza vaccination among nursing home (NH) residents during the 2008–2009 influenza season persisted in 2018–2019.

Methods

We conducted a cross-sectional study of NHs certified by the Centers for Medicare & Medicaid Services during the 2018–2019 influenza season in US states with ≥1% Black NH residents and a White–Black gap in influenza vaccination of NH residents (N = 2 233 392) of at least 1 percentage point (N = 40 states). NH residents during 1 October 2018 through 31 March 2019 aged ≥18 years and self-identified as being of Black or White race were included. Residents’ influenza vaccination status (vaccinated, refused, and not offered) was assessed. Multilevel modeling was used to estimate facility-level vaccination status and inequities by state.

Results

The White–Black gap in influenza vaccination was 9.9 percentage points. In adjusted analyses, racial inequities in vaccination were more prominent at the facility level than at the state level. Black residents disproportionately lived in NHs that had a majority of Blacks residents, which generally had the lowest vaccination. Inequities were most concentrated in the Midwestern region, also the most segregated. Not being offered the vaccine was negligible in absolute percentage points between White residents (2.6%) and Black residents (4.8%), whereas refusals were higher among Black (28.7%) than White residents (21.0%).

Conclusions

The increase in the White–Black vaccination gap among NH residents is occurring at the facility level in more states, especially those with the most segregation.
The Impact of Aging on Spatial Abilities in Deaf Users of a Sign Language
Authors: Luna Stéphanie , Joubert Sven , Blondel Marion , Cecchetto Carlo , Gagné Jean-Pierre
Published: September 2020

Research involving the general population of people who use a spoken language to communicate has demonstrated that older adults experience cognitive and physical changes associated with aging. Notwithstanding the differences in the cognitive processes involved in sign and spoken languages, it is possible that aging can also affect cognitive processing in deaf signers. This research aims to explore the impact of aging on spatial abilities among sign language users. Results showed that younger signers were more accurate than older signers on all spatial tasks. Therefore, the age-related impact on spatial abilities found in the older hearing population can be generalized to the population of signers. Potential implications for sign language production and comprehension are discussed.
An assessment of adherence to CARE reporting standards by case reports published in European Heart Journal – Case Reports in 2018
Authors: Freer Rosie , Rowett Alexandra , Camm C Fielder
Published: September 2020

Background

Case reports are subject to significant variation in their content, and the absence of pertinent case details can limit their benefit to the medical community. To aid this, a reporting standard (CARE) has been developed. Case reports published in European Heart Journal – Case reports (EHJ-CR) are subject to specific checks by editors to confirm compliance with the CARE reporting standard. However, a degree to which case reports published by EHJ-CR comply with the CARE reporting standards has not been established.

Methods

Case reports published in EHJ-CR during 2018 were reviewed for compliance with the CARE reporting standards. Two authors assessed each article for compliance with each of the 31 criteria.

Results

In 2018, 130 case reports/series were published by EHJ-CR. The median number of CARE criteria achieved by each article was 21 (interquartile range 21–25) out of 31. CARE criteria with the highest adherence were timeline inclusion, a clear and well-referenced discussion, and declaration of competing interests, all present in 100% of articles. In contrast, some aspects were poorly adhered to including patient perspective, and details of funding sources. There was no difference in overall compliance with aspects of the CARE standard between diagnostic and interventional case reports. However, lower compliance was seen for the discussion of diagnostic challenges in interventional studies (19%), when compared to diagnostic studies (44%). The continent of authorship and month submitted did not affect CARE adherence.

Conclusions

There was good compliance with the CARE reporting standards by case reports published in EHJ-CR. A number of specific areas for improvement have been identified which will be considered by the editorial board of EHJ-CR.
The drivers of Italian exports and product market entry: 1862–1913
Authors: Timini Jacopo
Published: September 2020

Between its unification and WWI, Italy’s changing export composition echoed its economic transformation. In this paper, I decompose Italian export growth in its margins and then analyze the determinants of Italian exports and product market entry (and exit). To do so, I use two different databases (aggregate and product-level bilateral trade data) and methodologies (gravity and logit models). Besides confirming some well-known empirical and historical facts for the Italian case (gravity variables hold; trade follows a Heckscher–Olhin pattern), the regression results offer a new perspective on two distinctive features of its history: trade policy and emigration. These two factors are positively associated with Italian exports and product market entry. These findings also have additional implications for the role of emigration on the course of the Italian economy: accounting for the trade channel, its overall effect may be larger than previously thought.
Sugar Maple, Red Maple, and Yellow Birch Growth and Mortality in Even-Aged Adirondack Northern Hardwoods
Authors: Nyland Ralph D , Bevilacqua Eddie , Ruff David A , Kiernan Diane H
Published: September 2020

Tree diameter growth models for northern hardwoods commonly used large data sets representing a composite of stands with varying management histories, structural characteristics, and age distributions. Yet common predictor variables like diameter can show differences in growth patterns for stands with different age structures and management histories. To address that, we modeled growth and mortality for sugar maple, red maple, and yellow birch in thinned even-aged Adirondack northern hardwoods. Findings indicate that change in diameter depends on initial diameter for sugar maple, with the rate decreasing exponentially from the largest size class to the smallest. Initial diameter did not prove significant with red maple and yellow birch in these thinned stands, perhaps because of the limited sample of trees of small diameter. Stand relative density and time since treatment affected growth for all three species. Those variables also proved significant for predicting mortality of sugar maple. Analyses revealed fewer losses of sugar and red maples among the larger diameter classes, but no relationship with diameter for yellow birch. Plot relative density did not affect mortality with red maple, but time after thinning had a significant effect on survival of all species.
Model Predictions of Postwildfire Woody Fuel Succession and Fire Behavior Are Sensitive to Fuel Dynamics Parameters
Authors: Kennedy Maureen C , Johnson Morris C , Harrison Sarah C
Published: September 2020

Computer models used to predict forest and fuels dynamics and wildfire behavior inform decisionmaking in contexts such as postdisturbance management. It is imperative to understand possible uncertainty in model predictions. We evaluated sensitivity of the Fire and Fuels Extension to the Forest Vegetation Simulator predictions to parameters that determine dynamics of standing dead trees (snags) and surface woody fuels. Predicted peak coarse and fine woody fuels were not sensitive to the decomposition rate of snags but were sensitive to decomposition rate of surface fuels regardless of initial snag density. Predictions of coarse woody fuel were sensitive to the snag fall rate when there was a higher initial density of snags. Fire behavior predictions were most sensitive to whether stylized fuel models or modeled fuels were used in calculations. When modeled fuels were used, fire behavior predictions were sensitive to the decomposition rate of surface fuels. Although this analysis does not inform the accuracy of model predictions, it does show where there is potential uncertainty in predictions of woody fuels succession and associated fire behavior. It is likely that any model that predicts postdisturbance fuel succession will also be sensitive to parameters that control snag dynamics and fuel decomposition.
Mixture of Triclopyr and Imazapyr More Effective than Triclopyr Alone for Hardwood Forest Stand Improvement
Authors: Turner Mark A , Gulsby William D , Harper Craig A
Published: September 2020

Treatment of individual trees in hardwood stands typically is conducted with herbicides that have no soil activity, such as triclopyr. However, triclopyr is not effective on some tree species. Applying a mixture of triclopyr and imazapyr would broaden the spectrum of species controlled, but nontarget mortality may be problematic as imazapyr may affect other trees through soil activity. We applied herbicide via girdle-and-spray as part of a forest stand improvement treatment in four upland hardwood stands in the Upper Coastal Plain of Alabama. We compared effects of using triclopyr alone with a mixture of triclopyr and imazapyr 18 months posttreatment. Only one untreated sweetgum (Liquidambar styraciflua) out of 440 trees was killed in the stands treated with the herbicide mixture (0.5 percent nontarget mortality rate). Nontarget mortality did not differ between treatments. However, the herbicide mixture controlled hickory (Carya spp.) and sourwood (Oxydendrum arboreum) better than triclopyr alone, with 56 percent of hickory treated with triclopyr still alive 18 months later, compared with 0 percent of hickory treated with the mixture. Our results indicate a mixture of triclopyr and imazapyr provides better control than triclopyr alone, and there is minimal risk to nontarget tree species in hardwood stands when used according to label recommendations.