bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel hermetically sealed device to realize unconventional phonon blockade at near-micron dimensions and milliKelvin temperatures
Authors: Nema Jayant K. , Gupta Srijan , Thakkar Riya , Rajagopal Prabhu
Published: January 2021

This paper proposes a novel design for a hermetically sealable device, consisting of charged linear and nonlinear membranes driven in the gigahertz range in vacuum setting, as a source of antibunched single phonons. Constraints for effecting phonon antibunching are found using the stationary Liouville–von Neumann master equation. Using analytical calculations and material and geometry optimization, we show that sizes of the proposed system can be upscaled to the near-micrometer range in a trade-off with the system operating temperature. The results are significant to realize quantum phononics, which has much promise as a modality for sensing and computing applications.
Optimal synchronization of laser pulses in THz generation scheme with colliding plasma wakes
Authors: Timofeev I. V. , Berendeev E. A. , Annenkov V. V. , Volchok E. P. , Trunov V. I.
Published: January 2021

This paper discusses optimal conditions for setting up a laboratory experiment on the generation of narrow-band THz radiation due to the head-on collision of two plasma wakes excited by a pair of femtosecond laser pulses in a supersonic helium jet. In this case, emission of electromagnetic waves at the second harmonic of the plasma frequency is caused by nonlinear interaction of counterpropagating plasma waves having different transverse potential profiles in the focus of the laser beams. Using particle-in-cell simulations, we study how strongly the efficiency of laser-to-terahertz energy conversion in this scheme is affected by the inhomogeneous electron density profile arising during field ionization of helium, as well as by the time-delay between arrivals of laser pulses to the focal point.
The dynamics of electron holes in current sheets
Authors: Shustov Pavel I. , Kuzichev Ilya V. , Vasko Ivan Y. , Artemyev Anton V. , Gerrard Andrew J.
Published: January 2021

We present 1.5D Vlasov code simulations of the dynamics of electron holes in non-uniform magnetic and electric fields typical of current sheets and, particularly, of the Earth's magnetotail current sheet. The simulations show that spatial width and amplitude of electron holes do not substantially vary in the course of propagation, but there arises a double layer localized around the electron hole and manifested as a drop of the electrostatic potential along the electron hole. We demonstrate that electron holes produced around the neutral plane of a current sheet slow down in the course of propagation toward the current sheet boundaries. The leading contribution to electron hole braking is provided by the non-uniform magnetic field although electrostatic fields typical of the current sheets do provide a noticeable contribution. The simulations also show that electron holes with larger amplitudes are slowed faster. The simulation results suggest that some of the slow electron holes recently reported in the Earth's plasma sheet boundary layer may appear due to braking of initially fast electron holes in the course of propagation in the current sheet.
Zonal profile corrugations and staircase formation: Role of the transport crossphase
Authors: Leconte M. , Kobayashi T.
Published: January 2021

Recently, quasi-stationary structures called E × B staircases were observed in gyrokinetic simulations, in all transport channels [Dif-Pradalier et al. Phys. Rev. Lett. 114, 085004 (2015)]. We present a novel analytical theory—supported by collisional drift-wave fluid simulations—for the generation of density profile corrugations (staircase), independent of the action of zonal flows: turbulent fluctuations self-organize to generate quasi-stationary radial modulations Δθk(r,t) of the transport crossphase θk between density and electric potential fluctuations. The radial modulations of the associated particle flux drive zonal corrugations of the density profile via a modulational instability. In turn, zonal density corrugations regulate the turbulence via nonlinear damping of the fluctuations.
Chaotic spin-photonic quantum states in an open periodically modulated cavity
Authors: Yusipov I. I. , Denisov S. V. , Ivanchenko M. V.
Published: January 2021

When applied to dynamical systems, both classical and quantum, time periodic modulations can produce complex non-equilibrium states which are often termed “chaotic.” Being well understood within the unitary Hamiltonian framework, this phenomenon is less explored in open quantum systems. Here, we consider quantum chaotic states emerging in a leaky cavity when the intracavity photonic mode is coherently pumped with the pumping intensity varying periodically in time. We show that a single spin when placed inside the cavity and coupled to the mode can moderate transitions between regular and chaotic regimes—that are identified by using quantum Lyapunov exponents or features of photon emission statistics—and thus can be used to control the degree of chaos.
Coherent terahertz radiation from a nonlinear oscillator of viscous electrons
Authors: Mendl Christian B. , Polini Marco , Lucas Andrew
Published: January 2021

Compressible electron flow through a narrow cavity is theoretically unstable, and the oscillations occurring during the instability have been proposed as a method of generating terahertz radiation. We numerically demonstrate that the end point of this instability is a nonlinear hydrodynamic oscillator, consisting of an alternating shock wave and rarefaction-like relaxation flowing back and forth in the device. This qualitative physics is robust to cavity inhomogeneity and changes in the equation of state of the fluid. We discuss the frequency and amplitude dependence of the emitted radiation on physical parameters (viscosity, momentum relaxation rate, and bias current) beyond linear response theory, providing clear predictions for future experiments.
Lagrangian study of the particle transport past a lateral, open-channel cavity
Authors: Engelen L. , Perrot-Minot C. , Mignot E. , Rivière N. , De Mulder T.
Published: January 2021

This paper presents a Lagrangian laboratory study of the passive tracer transport in and around a lateral, open-channel (square) cavity. Using 3D-particle tracking velocimetry (PTV), the trajectories of neutrally buoyant seeding particles are measured and analyzed to investigate the processes governing the particle exchanges between the cavity and the adjacent main stream for a selected subcritical flow condition. The tracked particles are classified using a Lagrangian approach based on their start and end positions, i.e., the cavity or the main stream region. Next, the spatial distribution of the particles at the main stream–cavity interface is analyzed to distinguish the typical transport processes of the different particle classes and identify preferential zones of net particle inflow, net particle outflow, and local zigzagging across the interface. Finally, this paper investigates the influence of the zigzag motion of particles on the (net) mass exchange coefficient. Derived from the same 3D-PTV dataset, a comparison between the common Eulerian (velocity-based) and Lagrangian mass exchange coefficients suggests that the transverse velocity method overestimates the net exchange significantly because of the particle zigzag motions.
Tuning proton conductivity and energy barriers for proton transfer
Authors: Young-Gonzales Amanda R. , Paddison Stephen J. , Sokolov Alexei P.
Published: January 2021

Proton transport is critical for many technologies and for a variety of biochemical and biophysical processes. Proton transfer between molecules (via structural diffusion) is considered to be an efficient mechanism in highly proton conducting materials. Yet, the mechanism and what controls energy barriers for this process remain poorly understood. It was shown that mixing phosphoric acid (PA) with lidocaine leads to an increase in proton conductivity at the same liquid viscosity. However, recent simulations of mixtures of PA with various bases, including lidocaine, suggested no decrease in the proton transfer energy barrier. To elucidate this surprising result, we have performed broadband dielectric spectroscopy to verify the predictions of the simulations for mixtures of PA with several bases. Our results reveal that adding bases to PA increases the energy barriers for proton transfer, and the observed increase in proton conductivity at a similar viscosity appears to be related to the increase in the glass transition temperature (Tg) of the mixture. Moreover, the energy barrier seems to increase with Tg of the mixtures, emphasizing the importance of molecular mobility or interactions in the proton transfer mechanism.
Study of the influences of different factors on the charged particles absorbed by the post-arc anode during the post-arc sheath expansion process in vacuum circuit breakers
Authors: Mo Yongpeng , Shi Zongqian , Jia Shenli
Published: January 2021

The dielectric recovery process has decisive effects on the current interruption process in vacuum circuit breakers, which has attracted the special attention of researchers. In commercial vacuum interrupters, ions and electrons of the residual plasma between the contact gap are separated and then fly to the electrodes under the effect of the transient recovery voltage after current zero. During this period, the post-arc current forms. During the formation of the post-arc current, ions also enter the post-arc anode due to their thermal motion. Therefore, the number of net electrons, which form the post-arc current, is only part of the total electrons between the contact gap at current zero. During the post-arc sheath expansion process, almost all electrons in the contact gap will enter the post-arc anode under the effects of the transient recovery voltage. If the proportion of ions and electrons, which enter the post-arc anode, can be obtained, the total number of electrons and consequently the residual plasma density between the contact gap could be estimated from the integration of the post-arc current. In this paper, the influences on the absorption of charged particles by the post-arc anode of some factors, e.g., rising rate of transient recovery voltage and metal vapor, have been simulated and discussed with a one-dimensional particle in cell-Monte Carlo collision model.
The role of counterions in ionic liquid crystals
Authors: Bartsch Hendrik , Bier Markus , Dietrich S.
Published: January 2021

Previous theoretical studies of calamitic (i.e., rod-like) ionic liquid crystals (ILCs) based on an effective one-species model led to indications of a novel smectic-A phase with a layer spacing being much larger than the length of the mesogenic (i.e., liquid–crystal forming) ions. In order to rule out the possibility that this wide smectic-A phase is merely an artifact caused by the one-species approximation, we investigate an extension that accounts explicitly for cations and anions in ILCs. Our present findings, obtained by grand canonical Monte Carlo simulations, show that the phase transitions between the isotropic and the smectic-A phases of the cation–anion system are in qualitative agreement with the effective one-species model used in the preceding studies. In particular, for ILCs with mesogens (i.e., liquid–crystal forming species) carrying charged sites at their tips, the wide smectic-A phase forms, at low temperatures and within an intermediate density range, in between the isotropic and hexagonal crystal phases. We find that in the ordinary smectic-A phase, the spatial distribution of the counterions of the mesogens is approximately uniform, whereas in the wide smectic-A phase, the small counterions accumulate in between the smectic layers. Due to this phenomenology, the wide smectic-A phase could be interesting for applications, which hinge on the presence of conductivity channels for mobile ions.
Universal spatio-topological control of crystallization in sessile droplets using non-intrusive vapor mediation
Authors: Hegde Omkar , Chattopadhyay Ankur , Basu Saptarshi
Published: January 2021

The present work showcases a mechanism of asymmetric solvent depletion using vapor-mediated interaction that can non-intrusively regulate the site of crystal precipitation. In general, the flow pattern inside a drying sessile saline droplet leads to circumferential deposition of salt crystals at the end of evaporation. Instead, we show that our proposed approach can manipulate the spatial location of crystal precipitation. The introduction of a pendant ethanol droplet near the sessile saline droplet’s vicinity creates an asymmetric ethanol vapor gradient around the sessile drop. The differential adsorption of ethanol vapor on the surface of the saline droplet gives rise to a spatial surface tension gradient. This, in turn, enhances the internal convection [∼O (102–103)] within the saline droplet. The vigorous and non-uniform flow promotes targeted contact line depinning, ensuring preferential segregation of the salt crystals. Using this methodology, we can inhibit crystal formation at selected locations and favorably control its deposition in definite regions. The interplay of flow hydrodynamics and the associated contact line motion governs this phenomenon marked by the inception and growth of crystals at a preferential site. The universal character of such a phenomenon is verified for a variety of salt solutions on the glass substrate. Tweaking of contact line motion using vapor mediation can be used as a strategic tool for controlling the salt crystallization sites for various potential applications starting from water purification to portable diagnostics, fouling, and scaling, particularly in cases that require the separation of unwarranted solutes from solvents.
ACTL6A promotes repair of cisplatin-induced DNA damage, a new mechanism of platinum resistance in cancer
Authors: Xiao Yang , Lin Fang-Tsyr , Lin Weei-Chin
Published: January 2021

Significance

Platinum resistance remains as a major issue in the therapy for many types of cancer. However, the mechanisms of resistance have not been fully elucidated.
ACTL6A
gene is frequently amplified in several types of cancer such as lung squamous cell carcinoma, ovarian cancer, and esophageal cancer. ACTL6A is a subunit shared by multiple complexes, including SWI/SNF, INO80, and NuA4/TIP60. We unveil a new role for ACTL6A in repairing cisplatin-induced DNA damage, providing a novel mechanism for cisplatin resistance. We also show that the action of ACTL6A in the repair of cisplatin-induced DNA lesions is through the SWI/SNF remodeling complex. Furthermore, we demonstrate that an HDAC inhibitor can abolish cisplatin resistance caused by ACTL6A overexpression.
Active feedforward control of flexural waves in an Acoustic Black Hole terminated beam
Authors: Cheer J , Hook K , Daley S
Published: January 2021

Acoustic Black Holes (ABHs) are structural features that are typically realised by introducing a tapering thickness profile into a structure that results in local regions of wave-speed reduction and a corresponding enhancement in the structural damping. In the ideal theoretical case, where the ABH tapers to zero thickness, the wave-speed reaches zero and the wave entering the ABH can be perfectly absorbed. In practical realisations, however, the thickness of the ABH taper and thus the wave-speed remain finite. In this case, to obtain high levels of structural damping, the ABH is typically combined with a passive damping material, such as a viscoelastic layer. This paper investigates the potential performance enhancements that can be achieved by replacing the complementary passive damping material with an active vibration control (AVC) system in a beam-based ABH, thus creating an active ABH (AABH). The proposed smart structure thus consists of a piezo-electric patch actuator, which is integrated into the ABH taper in place of the passive damping, and a wave-based, feedforward AVC strategy, which aims to minimise the broadband flexural wave reflection coefficient. To evaluate the relative performance of the proposed AABH, an identical AVC strategy is also applied to a beam with a constant thickness termination. It is demonstrated through experimental implementation, that the AABH is able to achieve equivalent broadband performance to the constant thickness beam-based AVC system, but with a lower computational requirement and a lower control effort, thus offering significant practical benefits.
Numerical modeling of non-stationary heat problems in a two-phase medium
Authors: Gladkikh V S , Ilin V P , Petukhov A V , Krylov A M
Published: January 2021

The simulation of thermal fields and melting permafrost is an important step for engineering construction in many regions of Russia. Water-ice phase transitions in a 3D complicated computation domain must be taken into account. The enthalpy statement with an implicit finite volume method was used to create a good discretization and a local mesh refinement to focus an area near the oil well. System of linear algebraic equations is solved using the iterative conjugate residual or conjugate gradient method in Krylov subspaces with the incomplete factorization algorithm in the Eisenstat modification as a preconditioner. A special high-parallel version of matrix generation and solving a system of the linear algebraic equations code have been developed and then efficiency has been estimated. The performance results of the developed code and temperature fields for different wells configuration (1 well and 4 wells placed as squared) during 5 years have been presented. The results validation was based on the comparison with previous papers and other algorithms. The results of simulations are close those to presented by other authors.
Nested Alternating - Triangular Incomplete Factorization Methods
Authors: Gololobov S V , Il’in V P , Krylov A M , Petukhov A V
Published: January 2021

We consider several versions of incomplete nested factorization methods for solving the large systems of linear algebraic equations (SLAEs) with sparse matrices which arise in grid approximations of the multi-dimensional boundary value problems. Our approach is based on the two-level iterative process in the Krylov subspaces in 3D case. Corresponding hierarchical incomplete factorization is applied to the block tridiagonal matrix structure. At the upper level, the diagonal blocks correspond to 2D grid subproblems which are factorized in the line-by-line framework. Instead of the low and upper triangular matrix factors, the alternating triangular matrices are used, which allows to apply the parallel counter sweeping approaches. The improvement of preconditioners is made by means of generalized compensation principles. To solve SLAE iterative conjugate direction methods in Krylov subspaces are applied. The efficiency of the proposed methods are demonstrated on the set of representative test problems.
Preconditioning methods based on spanning tree algorithms
Authors: Perevozkin D V , Omarova G A
Published: January 2021

The work continues the research performed by Chen and Toledo as a follow-up to Vaidya’s talk. The preconditioners being discussed are based on spanning tree algorithms where the input is the graph arising from the matrix of the system of linear algebraic equations (SLAE). The methods are considered in application to solving various SLAEs with real symmetric and non-symmetric matrices. The research shows that the application area of the preconditioners in question may significantly differ from the domain indicated in the literature.
Sign language recognition through Leap Motion controller and input prediction algorithm
Authors: Enikeev D G , Mustafina S A
Published: January 2021

The sign recognition systems are aimed to help deaf people communicate with society. In this paper we proposed our own concept of sign language recognition, which is based on a co-operative deep learning neural network, a text input prediction algorithm and a feedback from the user. We have pointed out the complexity of the Russian sign language and conceived the fingerspelling recognition. The method utilizes the natural properties of fingerspelling in order to increase the accuracy and recognition performance by predicting the ongoing letter. We also provide a detailed review of data acquisition in the related works. From a hardware perspective, we suggest using Leap Motion controller.
The PCA-seq method applied to analyze of the dynamics of COVID-19 epidemic indicators
Authors: Efimov V M , Polunin D A , Kovaleva V Y , Efimov K V
Published: January 2021

In time series analysis using the SSA method, a univariate series is converted into the multivariate one by shifts. The resulting trajectory matrix is subjected to principal component analysis (PCA). However, the principal components can also be computed using the PCA-Seq method if segments of the original series are selected as objects. The matrix of Euclidean distances between the objects can be obtained using any method, which offers additional opportunities for time series analysis compared to the conventional SSA. In this study, the PCA-Seq method was used to analyze the dynamics of COVID-19 epidemic indicators.
The least-squares collocation method in the mechanics of deformable solids
Authors: Golushko Sergey , Shapeev Vasily , Belyaev Vasily , Bryndin Luka , Boltaev Artem , Gorynin Arseniy
Published: January 2021

The paper is devoted to the application of the least-squares collocation method for solving the two- and one-dimensional problems in the mechanics of deformable solids. Calculation results of the deflections of isotropic and orthotropic elastic plates within the framework of various theories are presented. This paper shows that approximate solutions obtained by the hp-version of the least-squares collocation method converge with a high order and agree with analytical solutions of test problems with a high degree of accuracy. Numerical and mathematical modeling of three-point bending of composite beams was carried out taking into account nonlinear stress-strain relationships, multi-modulus behavior, and incipient fracture. It was found that the simulation results are in good agreement with the results of mechanical tests of three-point bending of composite beams.
On analytical and numerical solutions of inverse problems of the mechanics of composites
Authors: Golushko Sergey
Published: January 2021

A number of statements of inverse problems of rational and optimal design of composite structures are considered. The problem of maintenance of a momentless state of a composite shell with respect to parameters’ choice of reinforcement is solved. The problem of optimum design of composite pressure vessels is investigated.
On a singular value decomposition of the normal Radon transform operator acting on 3D 2-tensor fields
Authors: Polyakova A P , Svetov I E
Published: January 2021

We consider the problem of reconstructing the potential part of a symmetric 2-tensor field defined in a unit ball by its known values of the normal Radon transform. To solve the problem, a singular value decomposition of the normal Radon transform operator is constructed. The basis functions and fields using the Jacobi, Gegenbauer polynomials and spherical harmonics are constructed.
On nonconvex optimal control problems
Authors: Strekalovsky A S
Published: January 2021

The paper addresses the general optimal control (OC) problem with inequality constraints and a cost functional of Bolza given by d.c. functions with respect to the state in the terminal and integrand parts of the functionals. First, we reduce the original OC problem with inequality constraints to the one without constraints with the help of the Exact Penalization Theory. Further, we show that the auxiliary (penalized) problem also possesses the state-DC-structure. Employing this property, we develop the new Global Optimality Conditions (GOCs) and discuss some its features allowing to construct the new schemes of local and global searchers. Finally we elucidate the relations of the GOCs to the classical OC theory, in particular, to the Pontryagin’s maximum principle.
Integer linear models of network planning
Authors: Lyakhov O A
Published: January 2021

The application of integer linear programming for accurate solutions in project management is considered. The proposed network models for building schedules include works (operations) performed continuously and with interrupts. Examples of building optimal makespans using well known software for solving integer programming problems are given.
Coordinate basis adaptation of cataloging of unified immovable complexes included into the Russian-Chinese initiative project “One Belt – One Way” (by example railway transport)
Authors: Portnov A M
Published: January 2021

Coordinate support is a fundamental basis to study the characteristics of objects and phenomena which occur in the surrounding space. Parameterization of the characteristics is impossible if the rules for describing objects either within themselves or concerning their topological properties are not established. The rules for the metric description of the terrain objects at the level of general state geodetic and cartographic support tasks are determined. Nevertheless, there are quite important tasks to describe some elements of the sets for which the established rules are not considered as optimal, so it will be a more efficient solution to switch to alternative parameters of metric systems. Such objects include linear objects (such as real estate, buildings, natural objects) on the Earth’s surface which are characterized by a significant accumulation of errors in their description in the established coordinate systems (projections). If considered applied, there is some certain necessity to determine (calculate) the optimal rules (parameters) in a number of cases in order to form the metric system of their description for the design and departmental cataloging.
Preferential attachment in the citation network of scientific articles
Authors: Scherbakova N G , Bredikhin S V
Published: January 2021

We study the citation network of scientific articles in the hypothesis that the likelihood of connecting to a node depends on the node’s degree, a mechanism called the preferential attachment. We show that the rate at which articles acquire citations linearly depends on the number of citations already received and we find the functional form of the dependence basing on the analysis of the dynamic source data. We also investigate the effect of the article age on receiving citations and show that there is the exponential decay of interest to old articles. Nevertheless the distribution of citations has the power-law form.
Statistical filtering algorithms based on the maximum cross section method for stochastic systems with regime switching
Authors: Averina T , Rybakov K
Published: January 2021

New statistical algorithms are formed to estimate the state vector of stochastic systems with regime switching. These algorithms are based on the particle method, i.e., on numerical methods for solving stochastic differential equations, methods for modeling conditional Markov processes with a finite set of states, and methods for calculating weights. An important part of proposed algorithms is the use of the maximum cross section method and its modification, which allows the exact simulation of the regime switching process. This paper continues the authors’ research in the field of statistical methods and algorithms of the analysis and filtering for continuous-time stochastic systems.
A discontinuous particle method for the inviscid Burgers’ equation
Authors: Bogomolov S V , Filippova M A , Kuvshinnikov A E
Published: January 2021

The discontinuous particle method for simple problems associated with gas dynamics is under consideration. The origin of the method is based on the micro-model describing the movement of particles with prescribed velocities. We show that with the micro-model the inviscid Burgers’ equation is solved in a weak sense. Numerical experiments have confirmed a low viscosity of the method: the solution is smeared by only one particle.
Method for optimizing the shell of open pit mines based on parallel computing
Authors: Petrov D V , Mikhelev V M , Petrova E V
Published: January 2021

One of the main stages in design of mineral development process is solution of finding optimal open pit problem. It is necessary to take into account the spatial distribution of mineral components and the allowable slope angles of the sides during solving this problem. The basis for performing calculations to optimize the extraction of reserves is a digital block model of the mineral deposit. The larger and more accurate block model of the ore deposit requires more computationally complex calculation process. In this regard, using of parallel computing in this area is very relevant. The importance of solving this problem determined by the need to have an accurate model of the open pit at various stages of its development. This model depends from current cost of useful components and the costs of their extraction. This task formulated as the Ultimate Pit Problem (UPIT). Existing approaches for solving this problem does not use modern high-performance computing approaches. This complicates analysis of large models using existing methods. The long data processing time makes it difficult to increase the accuracy of the constructed quarry models, which in turn negatively affects decision-making on the field development plan and entails lost profit. In this paper analysed the methods of computer modelling open pits from the position of parallelizing computations during profit optimization and proposes a mathematical formulation of the problem of searching for open pit limits based on block extraction order graph.
Geotechnical properties of lateritic soil stabilized with sugarcane straw ash
Authors: Olowofoyeku A , Ofuyatan O , Oluwafemi J , Iroaganachi P
Published: January 2021

An increase in population with the demand of a wider road and also maintenance of transportation infrastructure has been alarming over the past few decades. Owing to this fact investigation will be carried out on laterite soil to improve the geotechnical properties of the soil to be able to stabilize the soil to withstand the load coming on it. In this investigation agricultural waste (sugarcane straw ash) will be used at varying percentage of 0, 4, 8, 10 and 12 to stabilized the laterite soil and improve the properties of the soil. The result indicates that with the increase of SCSA in the soil sample at 4% proportion ratio the soil strength is increased and at 12% it reduced drastically. The result of the tests shows that the strength of the soil is good when 4% SCSA are added. The optimum substitute increased the load bearing capacity of the soil thereby making an improvement to the lateritic soil.
Numerical approximation of second-order boundary value problems via hybrid boundary value method
Authors: Akinlabi G. O. , Busari A. A. , Abatan O. G. , Odunlami O. A.
Published: January 2021

Hybrid Boundary Value Method (HyBVM) is a new scheme, which is based on Linear Multistep Method (LMM). The HyBVM is the hybrid version of the Boundary Value Methods (BVMs) which are methods derived to overcome the limitations of the LMMs. This new scheme shares the same characteristic with the Runge Kutta method as data are utilized at off-step points. In this work, we apply this method to two second order Boundary Value Problems (BVPs) with mixed boundary conditions and the results are efficient when compared to other BVMs in literature.
Optimization and analysis of the packet switched network with focus on the 3G network
Authors: Oje A. A. , Edeki S. O.
Published: January 2021

A class of computer communications network that groups and passes data in the form of s mall packets is referred to as the PSN.. This research aimed at analyzing the Network output on 3 G Network, which is using Packet Switching. The Performance indices observed include the Received Signal Code Power (RSCP), the Energy per Chip to Spectral Noise density ratio, Handover Success Rate, and the Throughput. These indices were used to define the Coverage, accessibility, and data throughput of the Network.
Coupled method for the solution of a one-dimensional heat equation with axial symmetry
Authors: Edeki S. O. , Ogunniyi P. O. , Imaga O. F.
Published: January 2021

In this article, we implement the Projected Differential Transform Method (PDTM) coupled with Laplace Transform Method (LTM), hereby referred to as LPDTM, to solve a one-dimensional heat model (equation) with axial symmetry. Using the proposed framework (LPDTM), the exact solution (results) are obtained with convenience. It is noted that the suggested methodology performs very well and gives rapidly converging series solutions with less computational activities.
Nudging health care workers towards a flu shot: reminders are accepted but not necessarily effective. A randomized controlled study among residents in general practice in France
Authors: Barbaroux Adriaan , Benoit Laurie , Raymondie Romain A , Milhabet Isabelle
Published: January 2021

Background

A nudge corresponds to any procedure that influences choice architecture, without using persuasion or financial incentives. Nudges are effective in increasing vaccination with heterogeneous levels of acceptability.

Objective

To evaluate the effectiveness and acceptability of a nudge promoting influenza vaccination for general practice trainees, also called residents.

Methods

The hypothesis was that a reminder would be efficient and accepted and that prior exposure to a nudge increases its acceptability. Residents were randomly divided into three parallel experimental arms: a nudge group, a no-nudge group and a control group in order to evaluate the Hawthorne effect. The nudge consisted of providing a paper form for the free delivery of the vaccine and contacts for occupational health services.

Results

The analysis included 161 residents. There was a strong consensus among the residents that it is very acceptable to nudge their peers and patients. Acceptability was better with residents exposed to the nudge and with residents included in step 1 (Hawthorne effect). The nudge did not increase vaccination coverage.

Conclusion

The failure of this nudge highlights the importance of matching an intervention to the population’s needs. The experimental approach is innovative in this context and deserves further attention.

ClinicalTrials.gov pre-registration

NCT03768596
Evolution of Chi motifs in Proteobacteria
Authors: Buton Angélique , Bobay Louis-Marie
Published: January 2021

Homologous recombination is a key pathway found in nearly all bacterial taxa. The recombination complex not only allows bacteria to repair DNA double-strand breaks but also promotes adaption through the exchange of DNA between cells. In Proteobacteria, this process is mediated by the RecBCD complex, which relies on the recognition of a DNA motif named Chi to initiate recombination. The Chi motif has been characterized in Escherichia coli and analogous sequences have been found in several other species from diverse families, suggesting that this mode of action is widespread across bacteria. However, the sequences of Chi-like motifs are known for only five bacterial species: E. coli, Haemophilus influenzae, Bacillus subtilis, Lactococcus lactis, and Staphylococcus aureus. In this study, we detected putative Chi motifs in a large dataset of Proteobacteria and identified four additional motifs sharing high sequence similarity and similar properties to the Chi motif of E. coli in 85 species of Proteobacteria. Most Chi motifs were detected in Enterobacteriaceae and this motif appears well conserved in this family. However, we did not detect Chi motifs for the majority of Proteobacteria, suggesting that different motifs are used in these species. Altogether these results substantially expand our knowledge on the evolution of Chi motifs and on the recombination process in bacteria.
SPECIALIZED TRANSDUCTION WITH Λplac5: INVOLVEMENT OF THE RecE AND RecF RECOMBINATION PATHWAYS
Authors: Porter Ronald D
Published: January 2021

Several aspects of the recombination resulting from λplac5 transduction were investigated in strains of Escherichia coliK-12 that use the RecE or RecF recombination pathways. In a RecBC pathway strain, F42lac recombination with λplac5 is 20- to 50-fold higher than chromosomal lac times λplac5 recombination, and this recombination enhancement is largely dependent on constitutive expression of F42lac fertility functions. Here, it was observed that F42lac fertility functions do not effect the ability of F42lac to recombine with λplac5 in a RecE or RecF pathway strain. Therefore, the enhancement observed in a Rec+ (or RecBC pathway) strain is directly dependent on the recBC gene product. The end product of recombination between λplac5 and either F42lac or chromosomal lac in RecE and RecF pathway strains was monitored by scoring for addition and substitution transductants. It was observed that the percentage of addition transductants was lower in all cases for RecE and RecF pathway strains as compared with RecBC pathway or a recB strain. It is concluded that the introduction of sbcA or sbcB into a recB strain produces a change in recombination mechanism that is reflected in the nature of the end product of recombination.
CENTROMERE ORIENTATION OF QUADRIVALENTS OF HETEROZYGOUS TRANSLOCATIONS AND AN AUTOPLOID OF GOSSYPIUM HIRSUTUM L
Authors: Endrizzi J E , Ray D T , Gathman A C
Published: January 2021

Cytological observations of quadrivalents of heterozygous translocations in Gossypium hirsutum L. demonstrate that, in addition to alternate-1 and alternate-2 orientations, a third alternate orientation (alternate-3), which occurs as a three-dimensional, V-type configuration, can be identified.—Two additional types of disjunctions, the centromere orientations of which are rotational modifications of either adjacent or alternate configurations, were also observed in quadrivalents of a translocation heterozygote. These two types are rare, and both appear in the form of the Roman numeral X. The X and the alternate-3 types also occur in quadrivalents of an autoploid of G. hirsutum.—The two X types, along with adjacent-1, adjacent-2, alternate-1 and alternate-2 orientations, represent the six possible types of planar 2 x 2 random orientation of the four centromeres of a quadrivalent. Including the three-dimensional alternate-3 type, there are seven types of orientation.
A COMPARISON OF MUTATION RATES FOR SPECIFIC LOCI AND CHROMOSOME REGIONS IN DYSGENIC HYBRID MALES OF DROSOPHILA MELANOGASTER
Authors: Simmons Michael J , Raymond John D , Johnson Nancy A , Fahey Thomas M
Published: January 2021

The mutation rates of specific loci and chromosome regions were estimated for two types of dysgenic hybrid males. These came from crosses between P or Q males and M females in the P-M system of hybrid dysgenesis. The M × P hybrids were the more mutable for each of the loci and chromosome regions tested. The Beadex locus was highly mutable in these hybrids but did not mutate at all in the sample of gametes from the M × Q hybrids. The singed locus had 75% of the mutability of Beadex in the M × P hybrids; it was also mutable in the M × Q hybrids. The white locus was only slightly mutable in the M × P hybrids and not at all mutable in the M × Q hybrids. The mutations in singed and white probably arose from the insertion of P elements into these loci; the mutations at Beadex probably involved the action of a P element located near this locus on the X chromosome of the P strain that was used in the experiments. Mutations in two chromosome regions, one including the zeste-white loci and the other near the miniature locus, were much more frequent in the M × P hybrids than in the M × Q hybrids. These mutations also probably arose from P element insertions. The implication is that insertion mutations occur infrequently in the M × Q hybrids, possibly because most of the P elements they carry are defective. In M × P hybrids, there is variation among loci with respect to P elements mutagenesis, indicating that P elements possess a degree of insertional specificity.
THE EVOLUTION OF MULTIGENE FAMILIES UNDER INTRACHROMOSOMAL GENE CONVERSION
Authors: Nagylaki Thomas
Published: January 2021

A model for the evolution of the probabilities of genetic identity within and between loci of a multigene family in a finite population is formulated and investigated. Unbiased intrachromosomal gene conversion, equal crossing over between tandemly repeated genes, random genetic drift and mutation to new alleles are incorporated. Generations are discrete and nonoverlapping; the diploid, monoecious population mates at random. Formulas for the equilibrium values of the probabilities of identity and a cubic equation for the rate of convergence are deduced. Numerical examples indicate the following. The amount of homology at equilibrium generally decreases as the mutation rate, the population size and the number of repeats increase; it may increase or decrease with increasing crossover rate. The intralocus homology has an intermediate minimum, whereas the interlocus homology increases, as the rate of gene conversion increases. The intralocus homology decreases, whereas the interlocus homology increases, as the proportion of symmetric heteroduplexes increases. The characteristic convergence time can be sufficiently short to imply that intrachromosomal gene conversion may be an important mechanism for maintaining sequence homogeneity among repeated genes. The convergence time decreases as the conversion rate and the proportion of symmetric heteroduplexes increase; although exceptions occur, it generally increases as the population size and the number of repeats increase; it may increase or decrease with increasing crossover rate.
EXPRESSION OF A DNA REPLICATION GENE CLUSTER IN BACTERIOPHAGE T4: GENETIC LINKAGE AND THE CONTROL OF GENE PRODUCT INTERACTIONS
Authors: Gerald W L , Karam J D
Published: January 2021

The results of this study bear on the relationship between genetic linkage and control of interactions between the protein products of different cistrons. In T4 bacteriophage, genes 45 and 44 encode essential components of the phage DNA replication multiprotein complex. T4 gene 45 maps directly upstream of gene 44 relative to the overall direction of reading of this region of the phage chromosome, but it is not known whether these two genes are cotranscribed. It has been shown that a nonsense lesion of T4 gene 45 exerts a cis-dominant inhibitory effect on growth of a missense mutant of gene 44 but not on growth of phage carrying the wild-type gene 44 allele. In previous work, we confirmed these observations on polarity of the gene 45 mutation but detected no polar effects by this lesion on synthesis of either mutant or wild-type gene 44 protein. In the present study, we demonstrate that mRNA for gene 44 protein is separable by gel electrophoresis from gene 45-protein-encoding mRNA. That is, the two proteins are not synthesized from one polycistronic message, and the cis-dominant inhibitory effect of the gene 45 mutation on gene 44 function is probably expressed at a posttranslational stage. We propose that close genetic linkage, whether or not it provides shared transcriptional and translational regulatory signals for certain clusters of functionally related cistrons, may determine the intracellular compartmentalization for synthesis of proteins encoded by these clusters. In prokaryotes, such linkage-dependent compartmentation may minimize the diffusion distances between gene products that are synthesized at low levels and are destined to interact.
FORMATION OF CHROMOSOME REARRANGEMENTS BY P FACTORS IN DROSOPHILA
Authors: Engels William R , Preston Christine R
Published: January 2021

We studied a collection of 746 chromosome rearrangements all induced by the activity of members of the P family of transposable elements in Drosophila melanogaster. The chromosomes ranged from simple inversions to complex rearrangements. The distribution of complex rearrangement classes was of the kind expected if each rearrangement came about from a single multibreak event followed by random rejoining of chromosome segments, as opposed to a series of two-break events. Most breakpoints occurred at or very near (within a few hundred nucleotide pairs) the sites of preexisting P elements, but these elements were often lost during the rearrangement event. There were also a few cases of apparent gain of P elements. In cases in which both breakpoints of an inversion retained P elements, that inversion was capable of reverting at high frequencies to the original sequence or something close to it. This reversion occurred with sufficient precision to restore the function of a gene, held-up-b, which had been mutated by the breakpoint. However, some of the reversions had acquired irregularities at the former breakpoints that were detectable either by standard cytology or by molecular methods. The revertants themselves retained the ability to undergo further rearrangements depending on the presence of P elements. We interpret these results to rule out the simplest hypotheses of rearrangement formation that involve cointegrate structures or homologous recombination. The data provide a general picture of the rearrangement process and its possible relationship to transposition.
FUNCTIONAL INTERCHANGEABILITY OF DNA REPLICATION GENES IN SALMONELLA TYPHIMURIUM AND ESCHERICHIA COLI DEMONSTRATED BY A GENERAL COMPLEMENTATION PROCEDURE
Authors: Maurer Russell , Osmond Barbara C , Shekhtman Eugene , Wong Annette , Botstein David
Published: January 2021

Twenty-four genes from Salmonella typhimurium that affect DNA replication were isolated from a λ-Salmonella genomic library by lysogenic complementation of temperature-sensitive mutants of Salmonella or E. coli, using a new plaque complementation assay. The complementing λ clones, which make red plaques in this assay, and noncomplementing mutant derivatives, which make uncolored plaques, were used to further characterize the temperature-sensitive Salmonella mutants and to establish the functional similarity of E. coli and Salmonella DNA replication genes. For 17 of 18 E. coli mutants representing distinct loci, a Salmonella gene that complemented the mutant was found. This result indicates that single Salmonella replication proteins are able to function in otherwise all E. coli replication complexes and suggests that the detailed properties of Salmonella and E. coli replication proteins are very similar. The other seven Salmonella genes that were cloned were unrelated functionally to any E. coli genes examined. —As an aid to the derivation of chromosomal mutations affecting some of the cloned genes, a general method was developed for placing a transposon in the Salmonella chromosome in a segment corresponding to cloned DNA. Chromosomal mutations were derived in Salmonella affecting a gene (dnaA) that was cloned by complementation of an E. coli mutant by using the transposon-encoded drug resistance as a selectable marker in local mutagenesis.
GENETIC CONTROL OF MEIOSIS IN RICE, ORYZA SATIVA L. III. EFFECT OF DS GENES ON GENETIC RECOMBINATION
Authors: Kitada Kunio , Omura Takeshi
Published: January 2021

The recombination frequency as influenced by five independent recessive ds genes was measured on three segments of different chromosomes of rice, Oryza sativa L. Each ds gene in the homozygous condition resulted in an almost equally reduced recombination frequency in the three segments. When the mean reduction in recombination frequency was related to the reduction of chiasma frequency, the five ds genes were divided into two types: in one type the reduction of chiasma frequency almost corresponded to the mean reduction of recombination frequency, and in the other the chiasma frequency was greatly reduced in comparison with the mean reduction of recombination frequency. Three of the five ds genes were found to belong to the former group. In both types, normal synaptonemal complexes were observed in pachytene cells homozygous for ds genes. This finding suggests that ds genes do not affect the formation of synaptonemal complexes which are regarded as the prerequisite structure for crossing over.