Gradually Changing Research Articles

A tale of a changing basin - a transient model of the 7.17 event leading to the Messinian Salinity Crisis

Before the Messinian Salinity Crisis (MSC) left its imprint on the sediment record of the Mediterranean Sea in the form of evaporites, the basin had already undergone significant changes. At 7.17 Ma, a drop in δ13C values, as well as a basin-wide shift in the abundance of benthic foraminifers, already attest to a sudden change in the Mediterranean conditions.This event coincides with an increase in the amplitude of the insolation curve. It thus stands to question whether a change in the freshwater budget or a change in the connection between the Mediterranean Sea and the Atlantic was the driver for this event. Answering this question would not only help to understand the event itself, but might also help to decipher the early dynamics of the MSC.With a computational box model, we investigate the response of the Mediterranean Sea to a varying freshwater budget for a wide range of restriction. The results then let us define scenarios in which we analyse how a gradually changing restriction would express itself in the basin dynamics.We find that the change in the freshwater budget alone cannot explain the changes that are attributed with the 7.2 event, but coupled with an increase in restriction most differences can be accounted for. Our results also show that a gradual change in restriction can provoke a non-linear response in the behaviour of the basin, which can appear abrupt when happening on a short enough timescale. Such a change would also enhance the influence of said changes in the freshwater budget.This tells us that the processes that most likely triggered the Messinian Salinity Crisis started much earlier and incrementally increased the restriction of the Mediterranean Sea.

Gradual change of vibration characteristics of steel truss structure

Abstract In order to investigate the gradual change law of vibration characteristics of steel truss structures under the influence of fatigue loading and uniform corrosion, this study combines the nonlinear cumulative fatigue damage rule, corrosion depth theory, and structural residual performance theory to establish a multi-level gradually changing performance transfer model. The relationship between structural performance and damage behavior is revealed, and a numerical analysis method for the gradual change phenomenon of vibration characteristics of steel truss structures is provided. A two-dimensional finite element analysis framework for gradual changes in vibration characteristics in steel truss structures has been developed and analyzed for a steel truss girder bridge. The results show that the correlation terms of vibration characteristics gradually decay with the increase of operation time, and the degree of decay is related to the severity of fatigue damage or corrosion damage, with the overall trend exhibiting a three-stage change.

Detrital zircons of the vast Triassic Snadd and De Geerdalen formations, Barents Shelf, reveal temporal changes in sediment source

Studies of detrital-zircon age distributions from Triassic sedimentary rock successions on the Arctic Barents Shelf have resulted in different provenance interpretations. Here, we provide new U–Pb/Hf detrital-zircon data from eleven samples of the Snadd and De Geerdalen formations, covering the Barents Shelf in a north–south transect, that help refine the provenance of these sedimentary rocks and show how stratigraphic variations reflect changing source regions. The sample locations cover different stratigraphic levels and geographic locations within the formations. The detrital-zircon age spectra in the lower part (lowest Ladinian and lower Carnian) are dominated by two age peaks at 300 and 540 Ma, whereas the zircon distributions in the stratigraphically younger deposits (latest Carnian and early Norian) are dominated by a 235 Ma age peak and two minor peaks at 300 and 425 Ma. The apparent relative contribution of detritus of different ages changes gradually from lower to higher stratigraphic levels, marked by an increase in both the 235 and 425 Ma age peaks, a decrease in the 300 Ma component and a progressive loss of the 540 Ma age peak. The zircon Hf-isotopic compositions display predominantly juvenile zircon populations, except for a mixed juvenile and evolved signature in the youngest Permo-Triassic grains. A regional comparison of detrital-zircon age spectra in latest Carnian/early Norian deposits extends the depositional system into the Sverdrup Basin, supporting a much larger depositional system than hitherto known. The gradual change in detrital-zircon age spectra likely represents a gradual shift in zircon provenance. We interpret these variations to reflect an early source region in the north Urals, gradually changing to a dominant source region in the Taimyr Peninsula region.

Genomic Evolution in Pseudomonas fluorescens as a Result of Gradual Temperature Changes

As climate change continues to affect global temperatures, organisms will need to not only adapt but evolve to survive the changing climate conditions. Temperature selection experiments were performed on Pseudomonas fluorescens to select for growth at lower temperatures. The P. fluorescens temperature selection experiment selected for cells that can grow at a new minimum temperature which is over 20˚C lower than the optimal growth temperature (25-30˚C). Previous experiments established the low end of P. fluorescens’s growth temperature as 4˚C. The genomes of the newly selected and reference strains of P. fluorescens were sent for sequencing, and the results showed differences in protein sequence between the two strains. This experiment is a model for evolution as a result of gradual temperature change (similar to climate change) over generations, and the resulting genomic changes recorded show which protein families could evolve as an organism adapts to a gradually changing temperature.

A Trade-Off between Robustness to Environmental Fluctuations and Speed of Evolution.

AbstractUnderstanding how a species' life history affects its capacity to cope with environmental changes is important in the context of rapid climate changes. Reinterpreting previous results from a well-developed theoretical framework, we show that a trade-off exists between a species' ability to genetically adapt to long-term gradual environmental changes and its ability to demographically resist short-term environmental perturbations, causing variation in its vital rates. Surprisingly, this important insight has not been made formally explicit before. Choosing archetypal life histories along the fast-slow pace-of-life continuum and modeling their eco-evolutionary dynamics, we further show that long-lived species have larger demographic robustness to interannual fluctuations but limited trait evolutionary responses in gradually changing environments. In contrast, short-lived species had larger evolvability but reduced demographic robustness. This trade-off bears heavily on extinction probabilities of populations tracking fast trait changes in stochastic environments. Faster trait evolution in short-lived species came at the expense of their higher sensitivity to short-term fluctuations, causing higher extinction rates than for long-lived species. Long-lived species persisted better on short timescales but built maladaptation and an extinction debt over time. This work shows how modeling species' eco-evolutionary dynamics can help to assess species vulnerability to environmental changes.

Confidence intervals for point-of-stabilization of content uniformity.

Within the framework of continuous pharmaceutical manufacturing, we are interested in statistical modeling of the initial behavior of the production line. Assuming a gradually changing sequence of a suitable product quality characteristic (e.g., the content uniformity), we estimate the so-called point-of-stabilization (PoSt) and construct corresponding confidence regions based on appropriate asymptotic distributions and bootstrap. We investigate linear, quadratic, and nonlinear gradual change models both in homoscedastic and heteroscedastic setup. We propose a new nonlinear Emax gradual change model and show that it is applicable even if the true model is linear. Asymptotic distribution of the PoSt estimator is known only in a homoscedastic linear and quadratic model and, therefore, bootstrap approximations are used to construct one-sided PoSt confidence intervals.

Two kinds of sudden gains in brief psychotherapy

Objective Sudden gains (SGs) are known to predispose to good outcome in psychotherapy, especially in brief treatment. However, some SGs may be illusory, in the sense that they arise from measurement error in the context of gradual change. We examined change before, during, and after SGs that were either true or illusory. Method In a sample of 1,867 university students treated with brief psychotherapy, we simulated session data as gradually changing score sequences, identified artifactual SGs therein, and utilized the simulated data to categorize actual participant SGs as either illusory or true. Results During treatment, participants with illusory SGs (N = 42) improved as much as did participants with true SGs (N = 67). Moreover, late in treatment participants with SGs and their matched controls improved at similar rates. True SGs were preceded by more distress and were larger than illusory SGs. Among participants with true SGs, very large SGs were more likely to reverse later in treatment. Conclusions Relatively small SGs may reflect measurement error. When brief psychotherapy patients deteriorate early in treatment but then suddenly experience substantial improvement, little further change is to be expected.

Diverse gas composition controls the Moby-Dick gas hydrate system in the Gulf of Mexico

AbstractIn marine basins, gas hydrate systems are usually identified by a bottom simulating reflection (BSR) that parallels the seafloor and coincides with the base of the gas hydrate stability zone (GHSZ). We present a newly discovered gas hydrate system, Moby-Dick, located in the Ship Basin in the northern Gulf of Mexico. In the seismic data, we observe a channel-levee complex with a consistent phase reversal and a BSR extending over an area of ∼14.2 km2, strongly suggesting the presence of gas hydrate. In contrast to classical observations, the Moby-Dick BSR abnormally shoals 150 m toward the seafloor from west to east, which contradicts the northward-shallowing seafloor. We argue that the likely cause of the shoaling BSR is a gradually changing gas mix across the basin, with gas containing heavier hydrocarbons in the west transitioning to methane gas in the east. Our study indicates that such abnormal BSRs can be controlled by gradual changes in the gas mix influencing the shape of the GHSZ over kilometers on a basin scale.

Nitrogen-doped titanium dioxide nanorod array memristors with synaptic features and tunable memory lifetime for neuromorphic computing

Titanium dioxide memristors are promising next generation devices for neuromorphic computing, which can mimic synapses of human brain. With respect to meet satisfactory performance, gradual conductance changes and stability of cycling are essential. In this work, nitrogen-doped titanium dioxide nanorod arrays (N-TiO2 NARs) memristors with high performance have been fabricated using a hydrothermal process. The X-ray photo electron spectra confirm the existence of Ti‒N bonds, with uniform distribution of nitrogen confirmed by elemental mapping. The bidirectional gradually changing conductance and endurance of over 8000 cycles have been achieved. The ratio of high resistance state (HRS) and low resistance state (LRS) exceeds 16. The synaptic features, such as potentiation, depression, paired pulse facilitation (PPF), experience-learning and STDP have been achieved using continuous sweeping voltage and pulse trains respectively. It is possible to emulate the learning processes by stimulating the memristor using pulses of different amplitude, duration and interval. By manipulating the stimulation pulse duration, voltage and current compliance, memory lifetimes (MLTs) can be tuned from seconds to tens of thousands of seconds. These transitional processes are associated with anion vacancy creation/accumulation and diffusion. Those synaptic features and tunable MLTs provide a promising approach for neuromorphic computing.

Online Marketing Communication Trends in Slovak Hotel Industry

Abstract Research purpose. Traditionally used communication mix as a part of company’s marketing strategy, including advertising, sales promotion, personal sales and public relations, is gradually changing and expanding. Thanks to the development of new information-communication technologies, all these tools are constantly being transformed into the conditions of the Internet. This fact also affects consumer’s lifestyle, and thus, their buying behaviour. As a large part of consumers are almost always online via fixed internet, WIFI or within data, companies in various sectors, especially in service sector such as hotel industry, have a better opportunity to reach a specific target group with online marketing communication. The main goal of the article is to provide a literature review on online marketing communication from the viewpoint of several foreign and domestic authors, analyse its trends in hotel industry and propose measures for the efficient online marketing communication in Slovak hotels. Design/Methodology/Approach. To achieve the main goal of the article, general scientific methods as well as statistical methods such as descriptive statistics were used. The primary data were obtained from the questionnaire survey focused on the determination of the online marketing communication trends in the hotel industry by Slovak consumers. The size of the basic set was determined by using demographic statistics of the Statistical Office of the Slovak Republic and was consisted of inhabitants living in the Slovak Republic older than 15 years. In total, 390 respondents participated in the marketing survey. The survey took the form of computer-assisted web interviewing respecting the ICC/ESOMAR (International code on Market, Opinion and Social Research and Data Analytics). For the processing of the survey data, the quantitative assessment method was applied. The secondary data included domestic and foreign scientific works, statistical databases and annual companies reports. Findings. Gradual changes in society, including the advent of new communication technologies, have an impact on the changing attitudes and behaviour of consumers, especially represented by the new generations, who prefer communication with companies in the online environment. However, there is still a large number of companies in Slovakia, including the hotel industry, that underestimate the power of online marketing communication, and their activity in the online environment such as social media is often inadequate. Based on the analysis and results of the questionnaire survey, it is thus clear that implementation of online marketing communication in business strategy of Slovak hotels brings many benefits, including brand building, improving relationships with customers and increasing their brand loyalty. Originality/Value/Practical implications. Finally, measures for the efficient implementation of online marketing communication in the specific Slovak conditions are proposed, and opportunities for future research are recommended.

Spatial and temporal shift in the factors affecting the population dynamics of Calanus copepods in the North Sea.

The swap in abundance between two Calanus species in the North Sea during the 1980s constitutes a quintessential example of regime shift, with important ecosystemic and economic repercussions because these copepods constitute a major component of the diet of larval and juvenile cods. It is hypothesized that this transition was driven by gradual changes in primary productivity, the North Atlantic Oscillation (NAO) and sea surface temperatures (SST), and yet how these factors contribute to the population dynamics of these two species and the overall regime shift remains unclear. Here, we combine a highly resolved and spatially structured longitudinal dataset with population dynamics theory-based models to obtain a thorough and more detailed description of populations' responses to the regime shift observed in the North Sea. Our analyses highlight that this transition exhibits a clear spatial structure and involved a decoupling between the dynamics of Calanus finmarchicus and the NAO in western regions and between Calanus helgolandicus and SST in the eastern regions of the North Sea. Consequently, the observed switch in abundance between these species reflects the interaction between species-specific attributes, a well-defined spatial structure with a marked east-west axis and a decoupling between the ecological drivers and Calanus population dynamics following the shift. Succinctly, we suspect that higher water temperatures have favored C. helgolandicus and resulted in restrictive conditions for C. finmarchicus, eventually overshadowing the effects of NAO detected in historical records. Overall, our study illustrates how population dynamics theory can be successfully employed to disentangle the complex and multifactorial nature of a regime shift in response to gradually changing environmental conditions.

Biodiversity of insect pests of rice in India

Insect pests of rice are affected by climate change directly through physiological effects due to changes in temperature and precipitation and indirectly through effects due to changes in the quality of host plants. Species that depend on each other like plants and insects that pollinate them, do not always adapt to changes at the same time. The environmental changes alter both the timings and rate of interactions with food plants, competitors and natural enemies. Loss of genetic variability in the newly established host range tends to influence the ability of insect populations to adapt the changing climatic conditions involving new food plants, competitors and natural enemies. It is interesting to mention that the insect pest scenario of the crop gradually changing with gradual changes in crop cultivation practices and climate change, especially the higher temperature. Several major pests have become minor and many minor pests attained the status of major pests. There are records of many new pests shifting the host and also some invasive pests due to change in their habitat. There are many good examples of such changing insect pest scenario in rice crops.

Meso/Micro-texture analysis of the landslide-dam outburst sediments in the Upper Jinsha River, SE Tibetan Plateau

Outburst sediments are widely distributed in the Upper Jinsha River in the Southeastern (SE) Tibetan Plateau. In order to understand the sedimentary characteristics of these sediments, gravel fabric, particle size distribution and quartz sand surface textures were used to analyze the mesotextures and microtextures of the Xuelongnang outburst sediments. It was determined that these sediments usually have a short transport distance, and are distributed over a distance of approximately 3.5 km. The gravel fabric and particle size distribution analysis represent the different mesotextures with different transport distances and suggest gradually changing hydrodynamic conditions. The statistical data of quartz surface textures exhibit the transformation process of quartz sands by outburst flood. The variation from abundant sub-angular shapes (> 75%); to common V-shaped percussion cracks, solution crevasse, medium relief, and chatter marks (50% to 75%); to rare meandering ridge, underwater polished surface, large conchoidal fracture (> 100 μm), directional etch pits, and crystalline overgrowths (< 5%), present the features in different combinations to other sedimentary environments. The microtexture characteristics of landslide-dam outburst deposits are also consistent with those of the mesotextures. As the distance from the residual dam increased, the quartz grain microtextures showed gradual or abrupt changes, such as increased frequencies of V-shaped percussion cracks, decreased frequencies of the adhering particles, and growth of the solution crevasses. These findings could potentially be used as a discriminant mark to distinguish outburst sediment from other types of sediments, e.g., subaqueous, eolian, glacial, etc.

On ray tracing for sharp changing media.

Ray tracing is an integral part of modern imaging and inversion techniques. Several methods have been proposed depending on the requirements of the application. Some algorithms are best applied to fast changing material properties, like an interface between two differing media, while others are well suited to media with gradually changing properties, like composite materials. In this paper, an enhanced numerical algorithm for ray tracing is presented. Focus is given to solutions involving ordinary differential equations with initial-value conditions. The proposed algorithm is the result of a combination of two classical implementations and the authors show that it is well suited for media with both sharp and gradual changes in the index of refraction. Additionally, the authors present an application of ray path computation by using the technique known as the shooting method.

The effects of Botulinum toxin on the detection of gradual changes in facial emotion

When we feel sad or depressed, our face invariably “drops”. Conversely, when we try to cheer someone up, we might tell them “keep your smile up”, so presupposing that modifying the configuration of their facial muscles will enhance their mood. A crucial assumption that underpins this hypothesis is that mental states are shaped by information originating from the peripheral neuromotor system — a view operationalised as the Facial Feedback Hypothesis. We used botulinum toxin (BoNT-A) injected over the frown area to temporarily paralyse muscles necessary to express anger. Using a pre-post treatment design, we presented participants with gradually changing videos of a face morphing from neutral to full-blown expressions of either anger or happiness and asked them to press a button as soon as they had detected any change in the display. Results indicate that while all participants (control and BoNT-A) improved their reaction times from pre-test to post-test, the BoNT-A group did not when detecting anger in the post-test. We surmise that frown paralysis disadvantaged participants in their ability to improve the detection of anger. Our finding suggests that facial feedback causally affects perceptual awareness of changes in emotion, as well as people’s ability to use perceptual information to learn.

Symbolic regression in dynamic scenarios with gradually changing targets

Symbolic regression is a machine learning task: given a training dataset with features and targets, find a symbolic function that best predicts the target given the features. This paper concentrates on dynamic regression tasks, i.e. tasks where the goal changes during the model fitting process. Our study is motivated by dynamic regression tasks originating in the domain of reinforcement learning: we study four dynamic symbolic regression problems related to well-known reinforcement learning benchmarks, with data generated from the standard Value Iteration algorithm. We first show that in these problems the target function changes gradually, with no abrupt changes. Even these gradual changes, however, are a challenge to traditional Genetic Programming-based Symbolic Regression algorithms because they rely only on expression manipulation and selection. To address this challenge, we present an enhancement to such algorithms suitable for dynamic scenarios with gradual changes, namely the recently introduced type of leaf nodes called Linear Combination of Features. This type of leaf node, aided by the error backpropagation technique known from artificial neural networks, enables the algorithm to better fit the data by utilizing the error gradient to its advantage rather than searching blindly using only the fitness values. This setup is compared with a baseline of the core algorithm without any of our improvements and also with a classic evolutionary dynamic optimization technique: hypermutation. The results show that the proposed modifications greatly improve the algorithm ability to track a gradually changing target.

One Century of Forest Monitoring Data in Switzerland Reveals Species- and Site-Specific Trends of Climate-Induced Tree Mortality.

Climate-induced tree mortality became a global phenomenon during the last century and it is expected to increase in many regions in the future along with a further increase in the frequency of drought and heat events. However, tree mortality at the ecosystem level remains challenging to quantify since long-term, tree-individual, reliable observations are scarce. Here, we present a unique data set of monitoring records from 276 permanent plots located in 95 forest stands across Switzerland, which include five major European tree species (Norway spruce, Scots pine, silver fir, European beech, and sessile and common oak) and cover a time span of over one century (1898–2013), with inventory periods of 5–10 years. The long-term average annual mortality rate of the investigated forest stands was 1.5%. In general, species-specific annual mortality rates did not consistently increase over the last decades, except for Scots pine forests at lower altitudes, which exhibited a clear increase of mortality since the 1960s. Temporal trends of tree mortality varied also depending on diameter at breast height (DBH), with large trees generally experiencing an increase in mortality, while mortality of small trees tended to decrease. Normalized mortality rates were remarkably similar between species and a modest, but a consistent and steady increasing trend was apparent throughout the study period. Mixed effects models revealed that gradually changing stand parameters (stand basal area and stand age) had the strongest impact on mortality rates, modulated by climate, which had increasing importance during the last decades. Hereby, recent climatic changes had highly variable effects on tree mortality rates, depending on the species in combination with abiotic and biotic stand and site conditions. This suggests that forest species composition and species ranges may change under future climate conditions. Our data set highlights the complexity of forest dynamical processes such as long-term, gradual changes of forest structure, demography and species composition, which together with climate determine mortality rates.

Metabolic Patterning on a Chip: Towards in vitro Liver Zonation of Primary Rat and Human Hepatocytes

An important number of healthy and diseased tissues shows spatial variations in their metabolic capacities across the tissue. The liver is a prime example of such heterogeneity where the gradual changes in various metabolic activities across the liver sinusoid is termed as “zonation” of the liver. Here, we introduce the Metabolic Patterning on a Chip (MPOC) platform capable of dynamically creating metabolic patterns across the length of a microchamber of liver tissue via actively enforced gradients of various metabolic modulators such as hormones and inducers. Using this platform, we were able to create continuous liver tissues of both rat and human origin with gradually changing metabolic activities. The gradients we have created in nitrogen, carbohydrate and xenobiotic metabolisms recapitulated an in vivo like zonation and zonal toxic response. Beyond its application in recapitulation of liver zonation in vitro as we demonstrate here, the MPOC platform can be used and expanded for a variety of purposes including better understanding of heterogeneity in many different tissues during developmental and adult stages.

Electromagnetic absorption and thermoelastic analysis of a functionally graded wave absorber

Purpose As a good absorbing material candidate, a functionally graded wave absorber can be tailored to satisfy the impedance match principle by gradually changing material property. The paper aims to discuss these issues. Design/methodology/approach The electromagnetic wave absorption properties are discussed. An analysis model is proposed to provide an insight into its mechanical characteristics during wave absorption. Considering the energy-converting and thermal deformation properties, the thermoelastic behaviors of an absorber are analyzed by numerical method. The effects of material and geometrical properties are discussed in detail. Findings The results demonstrate that absorbing effect of graded composite is enhanced. Good performance of low reflectance and high absorption with gentle thermal stress distribution can be obtained by proper designing of the gradient absorber. Originality/value Functionally graded materials exhibit a progressive compositional gradient change along certain dimension of structures, which can be used as absorbing materials for the gradual change of material property tailored to satisfy the principle of impedance match. The design of functionally graded absorbing materials usually should consider not only the electromagnetic performance, but also the mechanical properties simultaneously. Therefore, few investigations have addressed the mechanical characteristics of absorbers. This paper presents some studies on the electromagnetic, especially mechanical behaviors during electromagnetic wave absorption. It is helpful to provide mechanical reference for designing an absorber.

Spatial and temporal dynamics of forest aboveground carbon stocks in response to climate and environmental changes

Climate change, especially global warming due to rising atmospheric carbon dioxide (CO2) concentration, has attracted much attention in the past century. Increasing efforts have been made to find solutions to mitigate the CO2 emission and sequester the existing CO2 in the atmosphere into land-based ecosystems. Forest ecosystems are the best effective way to fix the atmospheric CO2 by photosynthesis and allocate to tree biomass and into soils. Meanwhile, trees or forests will also respond to gradually increasing CO2 concentration and environment changes. It is important to quantify the dynamic interaction between the changing environment and activities of carbon (C) accumulation by forests with a proper method and also assess the status of the forest C stocks in response to climate and environmental changes. Estimation of forest aboveground C stock still experiences much uncertainty, even for the same forest ecosystem such as in the tropics, due to the different methods used. Most of the work has been based on inventory data and allometric equations to estimate biomass and calculate C stock by multiplying a C content coefficient. Great uncertainties exist because of the representativeness of the allometric equations, the differences in C content for different tree species, and the spatial heterogeneous nature of C distribution in the forest ecosystems. The development of remote sensing has stimulated applications of the technology in estimating forest aboveground C stocks at a larger scale. Remote sensing can reduce the uncertainty of spatial variations caused by extrapolation with the inventory methods, but it has the limitation of lacking the ability to express the processes involved in C accumulation and their responses to the changing environment. Tree growth and climate change information embedded in tree rings can be a good supplement to interpret the results acquired by the remote sensing technique. The application of remote sensing techniques offers a practical method for C stock estimates in forest ecosystems in the context of spatial variations. However, the long-term responses of forest C accumulation to the gradually changing environment and climate are still not well understood. Integrated study of combining remote sensing and ecological research techniques in forest ecosystems is necessary for future study to explore the mechanisms of interaction between forest development and the gradual changing environment and also to assess the C sequestration status and potential of forest ecosystems under climate change.