Introduction

This special themed section examines the multilayered engagements between Africa and the Soviet Union as a central, if overlooked, global encounter of the mid-twentieth century. We call this worldview and the entanglements it generated the “African-Soviet Modern,” an asymmetrical combination of aspiration, materiality, and practice that was rooted in diverse African states and in the Soviet Union. As an analytical category, the African-Soviet Modern speaks to the gap between the grand rhetorical and ideological scope of the Cold War moment and the relatively discrete channels in which it materialized, which gave this mode of thinking a particular vitality and instability. African-Soviet entanglements unfolded in an expansive and uneven geography that incorporated diverse regions of Africa, the USSR, and beyond. Avoiding the temporal and spatial silos of either Soviet or African history, the four essays in this section focus on the spaces where African and Soviet students, politicians, and scientists interacted with one another, creating “connected chronologies” and complementary archives of evidence. Weaving together documentary and oral sources, these articles recover a global entanglement that was energized by unbounded political, economic, and technological aspiration, but that produced an uneven material footprint in newly independent African states.

Analysis of on-pack messages for e-liquids: a discrete choice study

BackgroundPolicymakers wishing to encourage smokers unable to quit to switch to using electronic nicotine delivery systems (ENDS) also need to consider how to deter ENDS use among non-smokers. We examined whether reduced-risk messages could increase ENDS’ appeal among smokers and if increased-risk messages could decrease appeal among susceptible non-smokers, occasional and former smokers.MethodologyAn online discrete choice experiment tested three attributes: information message, nicotine content (0 mg or 3 mg) and flavour (tobacco, menthol or fruit). The sample comprised 352 current smokers, 118 occasional and former smokers, and 216 ENDS-susceptible never smokers. Smokers viewed reduced-risk messages that encouraged switching to ENDS, while other groups viewed increased-risk messages that discouraged ENDS use. All groups saw a typical addiction warning. We analysed the data by estimating multinomial logit regression and adjusted latent class analysis models.ResultsRelative to no message, reduced risk-messages increased the appeal of ENDS uptake among one class of smokers (33.5%) but decreased appeal among other smokers. However, among all smokers, reduced-risk messages increased preference more than a dissuasive addiction warning. By contrast, among occasional or former smokers, and susceptible non-smokers, all information messages discouraging ENDS use, including an addiction warning, decreased preference relative to no message.ConclusionsOn-pack relative-risk messages about ENDS could make transition more attractive to smokers while increased-risk messages could deter ENDS uptake among susceptible non-smokers, occasional and former smokers. Communicating diverse messages via discrete channels could recognise heterogeneity among and between smokers and non-smokers.

Communication Learning via Backpropagation in Discrete Channels with Unknown Noise

This work focuses on multi-agent reinforcement learning (RL) with inter-agent communication, in which communication is differentiable and optimized through backpropagation. Such differentiable approaches tend to converge more quickly to higher-quality policies compared to techniques that treat communication as actions in a traditional RL framework. However, modern communication networks (e.g., Wi-Fi or Bluetooth) rely on discrete communication channels, for which existing differentiable approaches that consider real-valued messages cannot be directly applied, or require biased gradient estimators. Some works have overcome this problem by treating the message space as an extension of the action space, and use standard RL to optimize message selection, but these methods tend to converge slower and to inferior policies. In this paper, we propose a stochastic message encoding/decoding procedure that makes a discrete communication channel mathematically equivalent to an analog channel with additive noise, through which gradients can be backpropagated. Additionally, we introduce an encryption step for use in noisy channels that forces channel noise to be message-independent, allowing us to compute unbiased derivative estimates even in the presence of unknown channel noise. To the best of our knowledge, this work presents the first differentiable communication learning approach that can compute unbiased derivatives through channels with unknown noise. We demonstrate the effectiveness of our approach in two example multi-robot tasks: a path finding and a collaborative search problem. There, we show that our approach achieves learning speed and performance similar to differentiable communication learning with real-valued messages (i.e., unlimited communication bandwidth), while naturally handling more realistic real-world communication constraints. Content Areas: Multi-Agent Communication, Reinforcement Learning.

Simulation of digital corrector of intersymbol signal distortions in the information transmission channel

A method of modeling a digital corrector of intersymbol distortions of signals in the information transmission channel, determining the optimal values of the weighting correctors when passing a sequence of random binary signals, checking the efficiency by determining the number of demodulation errors in signal distortion by noise. The demodulator adaptation model is shown, which is reduced to the calculation of the weighted sum of 4 samples of the input signal and the comparison of the obtained sum with the threshold. The basic operations on adaptation of weight coefficients of the corrector of the signals distorted by intersymbol interference at various types of transfer function of the channel of transfer of discrete signals are defined. The algorithm of the program for calculation of number of errors of demodulation at signal distortion by noises of intersymbol interference is offered. The calculation of the corrector optimization criterion is performed by the method of coordinate descent with the possibility of visualizing the iterative procedure of calculating the corrector optimization criterion at the selected values of the correction coefficients and calculation accuracy. The formation of the input and output signal is carried out using the built-in inverse fast Fourier transform function of the mathematical package MathCAD. The mathematical model of the digital corrector, which is a kind of FIR filter, allows us to investigate the effectiveness of compensation between character distortion and stationary linear distortion of information signals provided in discrete channels of information message transmission. The initial data for the calculation of the digital corrector are the readings of the pulse response, taken at time intervals in accordance with the conditions of Kotelnikov's theorem. To solve the system of linear algebraic equations when finding the coefficients of the digital corrector, the vector - matrix method of calculation and programming operators of the MathCAD system are used.

NOISE IMMUNITY OF THE ALGEBRAIC GEOMETRIC CODES

Linear block noise-immune codes constructed according to algebraic curves (algebraic geometric codes) are considered, their design properties are evaluated, algorithms of construction and decoding are studied. The energy efficiency of the transmission of discrete messages by M-ary orthogonal signals in the application of algebraic geometric codes is studied; the achievable energy gain from the use of noise-immune coding is estimated. The article shows that in discrete channels without memory it is possible to obtain a significant energy gain, which increases with the transition to long algebraic geometric codes constructed from curves with a large number of points relative to the genus of the curve. It is found that the computational complexity of implementing algebraic geometric codes is comparable to other known noise-immune codes, for example, Reed-Solomon codes and others. Thus, high energy efficiency in combination with the acceptable computational complexity of implementation confirms the prospects of algebraic geometric codes use in modern telecommunication systems and networks to improve the noise immunity of data transmission channels.

Modeling Discrete Channels Based on Gilbert Model using MATLAB Software

Examining the state of discrete channels requires the study of the physical and mathematical characteristics of these channels. The Gilbert model allows for the determination of the channel state for detecting and correcting errors mainly in discrete channels. In the Gilbert model, the channel can be in two cases. It is a good case that there are no errors, and in the worst case, an error with px is likely to occur. The need for error-free channels for discrete channels, as well as the use of discrete channels for data transmission, as well as the use of Virtual programs for error detection and correction. The article deals with the use of Gilbert's model to detect and correct errors in discrete channels, and to combat noise in providing reliability and resilience of information. In addition, Gilbert's model is based on the modeling of the discrete channels using the MATLAB software and the removal of detected errors by a virtual model.

Third Reel

This chapter assesses how, in Shivers (1975), David Cronenberg uses image and sound as discrete channels to extend narrative space and alter the significance of the visual information with the context provided by the aural. By coupling visual pleasure to aural infodump, Cronenberg not only smooths the audience's experience of a passage of pure exposition, but also qualifies their enjoyment in a way that produces a comic shudder. The chapter then considers exploitation cinema and exploitation film spectatorship. The film's association of a desiring female subject with fear raises the question of whether one is watching a misogynist film. The chapter also reflects on Cronenberg's Canadian liberalism. Moreover, it looks at the most significant evaluations of Shivers.

Dynamic microscale flow patterning using electrical modulation of zeta potential

The ability to move fluids at the microscale is at the core of many scientific and technological advancements. Despite its importance, microscale flow control remains highly limited by the use of discrete channels and mechanical valves, and relies on fixed geometries. Here we present an alternative mechanism that leverages localized field-effect electroosmosis to create dynamic flow patterns, allowing fluid manipulation without the use of physical walls. We control a set of gate electrodes embedded in the floor of a fluidic chamber using an ac voltage in sync with an external electric field, creating nonuniform electroosmotic flow distributions. These give rise to a pressure field that drives the flow throughout the chamber. We demonstrate a range of unique flow patterns that can be achieved, including regions of recirculating flow surrounded by quiescent fluid and volumes of complete stagnation within a moving fluid. We also demonstrate the interaction of multiple gate electrodes with an externally generated flow field, allowing spatial modulation of streamlines in real time. Furthermore, we provide a characterization of the system in terms of time response and dielectric breakdown, as well as engineering guidelines for its robust design and operation. We believe that the ability to create tailored microscale flow using solid-state actuation will open the door to entirely new on-chip functionalities.

Nonlinear transfer and temporal gain control in ON bipolar cells

The separation of visual input into discrete channels begins at the photoreceptor to bipolar cell synapse. Current models of the ON pathway describe the time-varying membrane voltage of ON bipolar cells as a linear function of light fluctuations. While this linearity holds under some visual conditions, stimulating the retina with full-field, high contrast flashes reveals a number of nonlinearities already present in the input current of ON bipolar cells. First, we show that the synaptic input to ON bipolar cells is asymmetric in response to equal flashes of opposite polarity. Next, we show that this asymmetry emerges because the responses to dark flashes increase linearly with contrast, whereas responses to bright flashes are highly rectified. We also describe how the outward current saturates in response to dark flashes of increasing duration. Furthermore, varying the inter-flash interval between a pair of high contrast flashes reveals a rapid, transient form of gain control that modulates both the amplitude and time course of the flash response. We develop a phenomenological model that captures the primary features of the ON bipolar cell response at high contrast. Finally, we discuss the implications of these nonlinearities in our understanding of how retinal circuitry shapes the visual signal.

Principles for reducing the phase shift between instantaneous analogue and discrete signals and the corresponding values in the sampled values (SV) stream of a digital substation

There are numerous publicly available articles on digital substations, including those dedicated to current and voltage measurements, time synchronization, test systems development, principles of substation design, and other aspects of this topic. But the phase shift between instantaneous signals and the corresponding values in the SV (sampled values) stream has been little discussed. We can list the following principles to reduce the phase shift between instantaneous analogue and discrete signals and the corresponding values in the SV stream. 1) Exclusion from the device, of non-essential elements that introduce additional propagation delays of analogue and discrete signals, provided that such exclusion does not adversely affect the device performance or characteristics. 2) Reduction of the delay time for the other device elements to the minimum values. 3) Adjustment of the delay time of some device elements or addition of special delay elements to equalize the time of signal propagation over analogue and discrete channels. 4) Consideration of the total delay time of signal propagation over analogue and discrete channels and adjustment of the time stamp in the SV frame. The article provides examples of application of these principles in signal generation and measuring devices and phase shift meters.