Global propagation of massive quantum fields in the plane gravitational waves and electromagnetic backgrounds

The behavior of massive quantum fields in the general plane wave spacetime and external, non-plane, electromagnetic waves is studied. The asymptotic conditions, the ``in" (``out") states and the cross sections are analysed. It is observed that, despite of the singularities encountered, the global form of these states can be obtained: at the singular points the Dirac delta-like behavior emerges and there is a discrete change of phase of the wave function after passing through each singular point. The relations between these phase corrections and local charts are discussed. Some examples of waves of infinite range (including the circularly polarized ones) are presented for which the explicit form of solutions can be obtained. All these results concern both the scalar as well as spin one-half fields; in latter case the change of the spin polarization after the general sandwich wave has passed is studied.

Optimal Planning of the Mobile Cargo Ropeway Repair Strategy

The focus of this research is to increase the reliability of mobile cargo ropeways formed by autonomous self-propelled transport units. The article deals with the development of a method for forming an effective technical and economic strategy for the restoration during planned repairs of those structural elements of transport units that can lead to critical failures of the ropeway. The method involves predicting the kinetics of the probability of failure-free operation of the ropeway during the entire life of its operation on the basis of predicting the failure-free operation of key elements of the transport units, the failure of which leads to an emergency disruption of the ropeway. In the process of integrating the system of Chapman-Kolmogorov differential equations, its periodic reformation is performed at the time of planned repairs, which allows us to take into account the need for a discrete change in the probability of failure-free operation of the restored structural elements. As a criterion for the optimality of the repairs strategy, the condition for obtaining the minimum total cost of repairs is used, while ensuring the average probability of failure-free operation. The formation of such an optimal strategy includes planning the schedules, number, time points, volume and cost of restoration work. The effectiveness of the repair strategy is determined by the total number of planned repairs and the minimum permissible probability of critical failure of structural elements. Conditions have been established under which further improvement of the level of ropeway reliability becomes an economically unprofitable task.

Creating a climate changed future with the sea level rise interactive- fiction game ‘Lagos2199’

Story-based futures serve an important role in climate change scenario development. Stories are particularly useful in exploring sea level rise possibilities, since we know many coastal areas are specifically vulnerable to accelerating rises in sea level. This discrete change in coastline is different from most other climate change impacts, and offers a clear basis for scientifically-informed, future scenarios. We demonstrate this with a creative world-building effort set in Lagos, Nigeria, in the year 2199. Further, we employ story-based scenario development, and create a learning-oriented, web-based game that allows users to experience stories in an open-ended, text-based adventure style. This collaborative process blended scientific research, story-telling, and artistic co-creation to iteratively construct the game ‘Lagos2199’. The first use-case of Lagos2199 is documented herein, with corresponding survey results from the student users. This work has three core conclusions. First, the unique reality that sea level rise will literally re-draw maps can be leveraged as an entry-point for world-building and scenario development of the future. Second, such a scenario can be blended with storytelling, art, and music to create a multi-dimensional, immersive exploration of ecological and social change. Third, this kind of game experience can serve an important pedagogical role in climate change education. Providing the next generation of citizens with fluency in both climate change impacts and how society will interact with such impacts, is critical for providing adaptive capacity over the coming decades and centuries of accelerating global change.

OPTICAL SIGHTS WITH INTERCHANGEABLE MAGNIFICATION

The article notes the development trend of optical sights made with a discrete change in magnification. Using two optical schemes in ideal components as an example, we consider the possibility of deviating from the classical approaches to the implementation of a discrete change in magnification to improve the performance of devices relative to existing analogs.

CORRECTION OF THE QUALITY OF CURRENT OF THE ELECTRIC NETWORK WITH A THYRISTOR REGULATOR OF AC VOLTAGE WITH ACTIVE-INDUCTIVE LOAD

The use of the AC voltage control method is considered. In this method, the improvement of the current quality of the supply network is achieved by a discrete change of the inductance in the network current flow circuit. In this method, it is proposed to use a circuit with counter-parallel thyristors and the neutral wire. The dependences of the harmonic coefficient and the current distortion coefficient of the electric network on the values of the regulated voltage are constructed. The obtained dependences prove the effectiveness of the proposed regulator. The required number of reactor sections is determined and the proper inductance of their windings to provide the values ​​of the harmonics coefficient that does not exceed 7% while adjusting the voltage depth of 50% on the active-inductive load. References 9, 3 figures 3, table.

Preprints in motion: tracking changes between posting and journal publication

Amidst the COVID-19 pandemic, preprints in the biomedical sciences are being posted and accessed at unprecedented rates, drawing widespread attention from the general public, press and policymakers for the first time. This phenomenon has sharpened longstanding questions about the reliability of information shared prior to journal peer review. Does the information shared in preprints typically withstand the scrutiny of peer review, or are conclusions likely to change in the version of record? We assessed preprints that had been posted and subsequently published in a journal between 1st January and 30th April 2020, representing the initial phase of the pandemic response. We utilised a combination of automatic and manual annotations to quantify how an article changed between the preprinted and published version. We found that the total number of figure panels and tables changed little between preprint and published articles. Moreover, the conclusions of 6% of non-COVID-19-related and 15% of COVID-19-related abstracts undergo a discrete change by the time of publication, but the majority of these changes do not reverse the main message of the paper.

Modeling Behavior as Dynamic Sequential States: Introduction to the Special Issue

This special issue of Evaluation and The Health Professions focuses on applications and extensions of latent transition analysis (LTA), a longitudinal parameterization of the latent class (LC) model. LTA is a model of discrete or qualitative change over time among potentially complex states (e.g., patterns of recent drug use or abuse experiences), commonly referred to as latent classes, latent profiles, or latent statuses. Frequently, researchers will distinguish the term “classes” for cross-sectional studies and with LTA use “statuses” to indicate the concept of “dynamic change” with individuals shifting in their response patterns and associated statuses over time. It goes without saying that LTA models are underutilized, although quite flexible. This special issue showcases articles that apply LTA and extend the capabilities of this approach to modeling discrete change in new ways.

Evaluation of metrological reliability of measuring instruments by method of generating functions

An article deals with problems related to the assessment of metrological reliability of measuring instruments by method of generating functions. Metrological reliability of measuring instruments is the most important characteristic that determines the accuracy and reliability of physical quantities measurements. In the suggested article, a confidence indicator is proposed as an evaluation of metrological reliability. The quantitative value of confidence indicator can be estimated by means of the method of generating functions. This is a scientific novelty of the work. Relevance of the problem of assessing the measuring instruments metrological reliability evaluation is substantiated in this paper since the current trend towards structural and functional complexity of measuring instruments may lead to decreasing of their reliability and, in particular, metrological reliability. The main goal of this work is to systematize the problems of reliability of measuring instruments and evaluate their metrological reliability using the method of generating functions. On the base of selected mathematical model of the evolution of error of measurement and proposed indicator of metrological reliability means of the method of generating functions allow to carry out metrological forecast of variability of the error of measurement depending on time. The model of gradual failures with a discrete change of the error over time, which is typical for a certain class of measuring instruments, for example, measuring time intervals, was chosen as a model for the evolution of the error of measuring instruments. The method of generating functions used for evaluating the metrological reliability of measuring instruments has made it possible to increase the efficiency of the algorithm for quantitative evaluation of metrological reliability of measuring instruments by simplifying the mathematical operations that underlie it.

Down regulation of vestibular balance stabilizing mechanisms to enable transition between motor states

The neural control of transition between posture and movement encompasses the regulation of reflex-stabilizing mechanisms to enable motion. Optimal feedback theory suggests that such transitions require the disengagement of one motor control policy before the implementation of another. To test this possibility, we investigated the continuity of the vestibular control of balance during transitions between quiet standing and locomotion and between two standing postures. Healthy subjects initiated and terminated locomotion or shifted the distribution of their weight between their feet, while exposed to electrical vestibular stimuli (EVS). The relationship between EVS and ground reaction forces was quantified using time-frequency analyses. Discontinuities corresponding to null coherence periods were observed preceding the onset of movement initiation and during the step preceding locomotion termination. These results show humans interrupt the vestibular balance stabilizing mechanisms to transition between motor states, suggesting a discrete change between motor control policies, as predicted by optimal feedback theory.