Imperfect Reversal Research Articles

Deep Learning for Predictive Analytics in Reversible Steganography

Deep learning is regarded as a promising solution for reversible steganography. There is an accelerating trend of representing a reversible steo-system by monolithic neural networks, which bypass intermediate operations in traditional pipelines of reversible steganography. This end-to-end paradigm, however, suffers from imperfect reversibility. By contrast, the modular paradigm that incorporates neural networks into modules of traditional pipelines can stably guarantee reversibility with mathematical explainability. Prediction-error modulation is a well-established reversible steganography pipeline for digital images. It consists of a predictive analytics module and a reversible coding module. Given that reversibility is governed independently by the coding module, we narrow our focus to the incorporation of neural networks into the analytics module, which serves the purpose of predicting pixel intensities and a pivotal role in determining capacity and imperceptibility. The objective of this study is to evaluate the impacts of different training configurations upon predictive accuracy of neural networks and provide practical insights. In particular, we investigate how different initialisation strategies for input images may affect the learning process and how different training strategies for dual-layer prediction respond to the problem of distributional shift. Furthermore, we compare steganographic performance of various model architectures with different loss functions.

Gasoline demand in the United States: An asymmetric economic analysis

Gasoline price in the United States has been characterized by extreme instability throughout the last two decades. Empirical literature commonly presumes a perfect symmetric reaction from consumers. However, there are reasons to believe that gasoline demand reductions following the price increases will not be entirely reversed by a price cut or vice versa. Using U.S. aggregate data and data of nine U.S. states’ gasoline consumers during the period 1986–2021, we examine gasoline demand’s asymmetry or imperfect reversibility to changes in gasoline prices. Instrumental variables are used to correct the potential endogeneity of gasoline prices. The finding indicates that at the national level, the demand of gasoline responds asymmetrically to price changes, suggesting possible imperfect reversibility in consumer behavior. However, the results differ across the states analyzed. This finding helps predict energy consumption and assist tax policy decisions and pricing strategy.

Kelp Forests: Catastrophes, Resilience, and Management

Resilient kelp forests provide foundation habitat for marine ecosystems and are indicators of the ecosystems’ sustainable natural capital. Loss of resilience and imperfectly reversible catastrophic shifts from kelp forests to urchin barrens, due to pollution or loss of a top predator, are part of an ecological tipping point phenomenon, and involve a loss in sustainable natural capital. Management controls to prevent or reverse these shifts and losses are classified in a number of ways. Systemic controls eliminate the cause of the problem. Symptomatic controls use leverage points for more direct control of the populations affected, urchin harvesting or culling, or kelp enhancement. There is a distinction between ongoing structural (press) controls versus temporary or intermittent perturbation (pulse) controls, and one between shift preventing versus shift reversing or restorative controls. Adaptive management and the options it creates both focus on reductions in uncertainty and control policies with the flexibility to take advantage of those reductions. The various management distinctions are most easily understood by modeling the predator-urchin-kelp marine ecosystem. This paper develops a mathematical model of the ecosystem that has the potential for two different catastrophic shifts between equilibria. Pulse disturbances, originating from exogenous abiotic factors or population dynamics elsewhere in the metacommunity, can activate shifts. A measure of probabilistic resilience is developed and used as part of an assessment of the ecosystem’s sustainable stock of natural capital. With perturbation outcomes clustered around the originating equilibrium, hysteresis is activated, resulting imperfect reversibility of catastrophic shifts, and a loss in natural capital. The difficulty of reversing a shift from kelp forest to urchin barren, with an associated loss in sustainable natural capital, is an example. Management controls are modeled. I find that systemic and symptomatic, and press and pulse, controls can be complementary. Restorative controls tend to be more difficult or costly than preventative ones. Adaptive management, favoring flexible, often preventative, controls, creates option value, lowering control costs and/or losses in sustainable natural capital. Two cases are used to illustrate, Tasmania, Australia and Haida Gwaii, Canada.

Imperfect reversibility of fuel demand for road transport: Asymmetric and hysteretic effects of income and price changes in Korea

Existing literature lacks empirical evidence of the potential nonlinear effects of income and price on transport fuel demand. This paper fills this gap by investigating whether the demand responses to income and price changes are asymmetric and hysteretic. To this end, we decompose both income and price into two- and three-component series (one- and two-threshold cases). In the one-threshold case, demand effects for income are symmetric, but asymmetric for fuel price. The results of the two-threshold case show hysteretic effects for price but not for income. More specifically, the results reveal that small price changes do not significantly influence fuel demand for road transport, but substantial increases and cuts in price asymmetrically affect fuel demand, supporting the presence of an inaction band. These findings lead to the conclusion that income has linear demand effects, but demand effects for fuel price are nonlinear; therefore, disregarding nonlinearities in fuel price changes can be restrictive.

Retail promotion with price cut and the imperfect price responses of orange juice demand in the U.S.

AbstractThe purpose of this study is to investigate imperfect price reversibility and measure price sensitivity incorporated with the effect of trade promotions for refrigerated 100% orange juice (OJ). Using a price decomposition method with distributed lags, we test imperfect reversibility and asymmetric price responses. Empirical models consisted of prices coupled with promotions and prices decoupled from promotions to determine the effect of trade promotions on retail prices. The results showed that the demand for OJ was imperfectly price reversible when we used prices coupled with promotion, and asymmetric price responses were found in not from concentrated OJ demand. Prices coupled with promotions were more elastic than prices decoupled from promotions. The demand for OJ was influenced by both current and previous information. Dynamic adjustments toward price and promotions may result in irreversibility. Competitions with price reduction increase sales in the short run, but frequent promotions may lead to lower reference prices that eventually weaken consumer willingness to purchase at regular prices without promotions. [EconLit citations: C32, Q11, Q13].

Imperfect reversibility of air transport demand: Effects of air fare, fuel prices and price transmission

There are recent evidence that air transport demand may not have a perfectly reversible relationship with income and jet fuel prices, as is assumed in most demand models. However, it is not known if the imperfectly reversible effects of jet fuel price are a result of asymmetries in the supply side, i.e., asymmetries in cost pass through from fuel prices to air fare, or of demand side behavioral asymmetries whereby people value gains and losses differently. This paper uses US time series data and decomposes air fare and fuel price into three component series to develop an econometric model of air transport demand that is capable of capturing the potential imperfectly reversible relationships and test for the presence or absence of reversibility. We find that air transport demand shows asymmetry with respect to air fare, indicating potential imperfect reversibility in consumer behavior. We also find evidence of asymmetry and hysteresis in cost pass-through from jet fuel prices to air fare, showing rapid increases in airfare when fuel prices increases but a slower response in the opposite direction.

The asymmetric effects of income and fuel price on air transport demand

Forecasts of passenger demand are an important parameter for aviation planners. Air transport demand models typically assume a perfectly reversible impact of the demand drivers. However, there are reasons to believe that the impacts of some of the demand drivers such as fuel price or income on air transport demand may not be perfectly reversible. Two types of imperfect reversibility, namely asymmetry and hysteresis, are possible. Asymmetry refers to the differences in the demand impacts of a rising price or income from that of a falling price or income. Hysteresis refers to the dependence of the impacts of changing price or income on previous history, especially on previous maximum price or income. We use US time series data and decompose each of fuel price and income into three component series to develop an econometric model for air transport demand that is capable of capturing the potential imperfectly reversible relationships and test for the presence or absence of reversibility. We find statistical evidence of asymmetry and hysteresis – for both, prices and income – in air transport demand. Implications for policy and practice are then discussed.

Absence of exponential sensitivity to small perturbations in nonintegrable systems of spins 1/2

We show that macroscopic nonintegrable lattices of spins 1/2, which are often considered to be chaotic, do not exhibit the basic property of classical chaotic systems, namely, exponential sensitivity to small perturbations. We compare chaotic lattices of classical spins and nonintegrable lattices of spins 1/2 in terms of their magnetization responses to an imperfect reversal of spin dynamics known as Loschmidt echo. In the classical case, magnetization is exponentially sensitive to small perturbations with a characteristic exponent equal to twice the value of the largest Lyapunov exponent of the system. In the case of spins 1/2, magnetization is only power-law sensitive to small perturbations.

A New Statistical Model and a Redefinition of Isotopic Ratio

Ultra-microanalysis of isotopes is required to clarify the origin, structure, and history of extremely small samples, for example micrometeorites and aerosols. However, a decrease in the number of measured atoms reveals a serious problem in the concept of isotopic ratio. The first fundamental defect of the isotopic ratio concept is imperfect reversibility of numerator and denominator, leading to two isotopic compositions inconsistent with each other. Secondly, the probability distribution of isotopic ratio is not the same as the binominal distribution, indicating that the mean isotopic ratio is systematically higher than the true isotopic ratio. Since these demerits should be avoided in ultra-microanalysis as much as possible, isotopic abundance or relative isotopic abundance should be used rather than isotopic ratio. The concept of isotopic ratio is, however, widely used in geochemical and cosmochemical fields, making it very difficult to abandon. Therefore, the potential uncertainty of isotopic ratio and the gap between the obtained isotopic ratio and the true one deriving from the number of sampling atoms and the isotopic ratio are vigorously evaluated here. In addition, a confirmation requirement for confirming an anomalous isotopic ratio is provided. The statistical model shown in the present work clearly indicates that the major isotope must be set as the denominator of isotopic ratio, i.e. isotopic ratio must be below 1, to reduce the effects of distorted probability distribution of isotopic ratio. In the precise measurement of isotopes, the potential error and disagreement with the true value must be tested when the number of sampled atoms is extremely few. Serious problems have not been occurred in research up to the present even in the case of NanoSIMS measurements, but this is because a sufficient number of atoms was analyzed and only extremely large isotopic anomalies were investigated. The correction and evaluation methods established in this paper will be required for accurate ultra-microanalysis.

Single-Transition Coherence Transfer by Adiabatic Cross Polarization in NMR

Spin-state selective coherence transfer between single-transition coherences in a scalar-coupled two-spin system may be achieved by employing highly selective, constant amplitude radio frequency fields. We extend this method by employing amplitude-modulated pulses to achieve an adiabatic transfer, as shown in the picture (I=intensity). Different limiting cases are considered. The imperfect reversibility of the transfer reveals deviations from adiabaticity.

Single-Transition Coherence Transfer by Adiabatic Cross Polarization in NMR

Spin-state selective coherence transfer between single-transition coherences in a scalar-coupled two-spin system may be achieved by employing highly selective, constant amplitude radio frequency fields. We extend this method by employing amplitude-modulated pulses to achieve an adiabatic transfer, as shown in the picture (I=intensity). Different limiting cases are considered. The imperfect reversibility of the transfer reveals deviations from adiabaticity.