Journal articles on the topic 'Sample paths regularity'

The linear multifractional stable motion (LMSM) processes Y = {Y(t)}t∈ℝ is an α-stable (0 < α < 2) stochastic process, which exhibits local self-similarity, has heavy tails and can have skewed distributions. The process Y is obtained from the well-known class of linear fractional stable motion (LFSM) processes by replacing their self-similarity parameter H by a function of time H(t). We show that the paths of Y(t) are bounded on bounded intervals only if 1/α ≤ H(t) < 1, t ∈ ℝ. In particular, if 0 < α ≤ 1, then Y has everywhere discontinuous paths, with probability one. On the other hand, Y has a version with continuous paths if H(t) is sufficiently regular and 1/α < H(t), t ∈ ℝ. We study the Hölder regularity of the sample paths when these are continuous and establish almost sure bounds on the pointwise and uniform pointwise Hölder exponents of the (random) function Y(t,ω), t ∈ ℝ, in terms of the function H(t) and its corresponding Hölder exponents. The Gaussian multifractional Brownian motion (MBM) processes are LMSM processes when α = 2. We obtain some new results on the Hölder regularity of their paths.

We consider a stochastic boundary value elliptic problem on a bounded domain D ⊂ ℝk, driven by a fractional Brownian field with Hurst parameter H = (H1,…,Hk) ∈ [½, 1[k. First, we define the stochastic convolution derived from the Green kernel and prove some properties. Using monotonicity methods, we prove the existence and uniqueness of solution along with regularity of the sample paths. Finally, we propose a sequence of lattice approximations and prove its convergence to the solution of the SPDE at a given rate.

We analyze the solution to the linear stochastic heat equation driven by a multiparameter Hermite process of order [Formula: see text]. This solution is an element of the [Formula: see text]th Wiener chaos. We discuss various properties of the solution, such as the necessary and sufficient condition for its existence, self-similarity, [Formula: see text]-variation and regularity of its sample paths. We will also focus on the probability distribution of the solution, which is non-Gaussian when [Formula: see text].

For random fields with fractional regularity order (respectively, fractional singularity order), an orthogonal decomposition of the associated reproducing kernel Hilbert space with respect to domains with fractal boundary is derived. The approach presented is based on the theory of generalized random fields on fractional Sobolev spaces. The orthogonal decomposition derived is equivalent to the weak-sense Markov condition, in the second-order moment sense, studied in Ref. 50, and based on the concept of splitting Hilbert spaces. A mean-square fractional order differential representation on bounded domains with fractal boundary is also obtained. In the Gaussian case, the random fields studied have fractal sample paths (see Ref. 1). Examples of fractional-order differential models in the class considered are provided.

In this paper, stochastic differential equations in a Hilbert space with a standard, cylindrical fractional Brownian motion with the Hurst parameter in the interval (1/2,1) are investigated. Existence and uniqueness of mild solutions, continuity of the sample paths and state space regularity of the solutions, and the existence of limiting measures are verified. The equivalence of the probability laws for the solution evaluated at different times and different initial conditions and the convergence of these probability laws to the limiting probability are verified. These results are applied to specific stochastic parabolic and hyperbolic differential equations. The solution of a specific parabolic equation with the fractional Brownian motion only in the boundary condition is shown to have many results that are analogues of the results for a fractional Brownian motion in the domain.

Starting from the moving average representation of fractional Brownian motion, there are two different approaches to constructing fractional Lévy processes in the literature. Applying L2-integration theory, one can keep the same moving average kernel and replace the driving Brownian motion by a pure jump Lévy process with finite second moments. Alternatively, in the framework of alpha-stable random measures, the Brownian motion is replaced by an alpha-stable Lévy process and the exponent in the kernel is reparametrized by H - 1/α. We now provide a unified approach taking kernels of the form [Formula: see text], where γ can be chosen according to the existing moments and the Blumenthal–Getoor index of the underlying Lévy process. These processes may exhibit both long and short range dependence. In addition we will examine further properties of the processes, e.g., regularity of the sample paths and the semimartingale property.

The identification of diffusion processes is challenging for many real-world systems with sparsely sampled observation data. In this work, we propose a data augmentation-based sparse Bayesian learning method to identify a class of diffusion processes from sparsely sampled data. We impute latent unsampled diffusion paths between adjacent observations and construct a candidate model for the diffusion processes with the sparsity-inducing prior on model parameters. Given the augmented data and candidate model, we investigate the full joint posterior distribution of all the parameters and latent diffusion paths under a Bayesian learning framework. We then design a Markov chain Monte Carlo sampler with non-degenerate acceptance probability on system dimension to draw samples from the posterior distribution to estimate the parameters and latent diffusion paths. Particularly, the proposed method can handle sparse data that are regularly or irregularly sampled in time. Simulations on the well-known Langevin equation, homogeneous diffusion in a symmetric double-well potential, and stochastic Lotka–Volterra equation demonstrate the effectiveness and considerable accuracy of the proposed method.

AbstractWe study how to sample paths of a random walk up to the first time it crosses a fixed barrier, in the setting where the step sizes are independent and identically distributed with negative mean and have a regularly varying right tail. We introduce a desirable property for a change of measure to be suitable for exact simulation. We study whether the change of measure of Blanchet and Glynn (2008) satisfies this property and show that it does so if and only if the tail index α of the right tail lies in the interval (1, 3/2).

Fractional Lévy processes generalize fractional Brownian motion in a natural way. We go a step further and extend the usual fractional Riemann-Liouville kernel to a regularly varying function. We call the resulting stochastic processes generalized fractional Lévy processes (GFLPs) and show that they may have short or long memory increments and that their sample paths may have jumps or not. Moreover, we define stochastic integrals with respect to a GFLP and investigate their second-order structure and sample path properties. A specific example is the Ornstein-Uhlenbeck process driven by a time-scaled GFLP. We prove a functional central limit theorem for such scaled processes with a fractional Ornstein-Uhlenbeck process as a limit process. This approximation applies to a wide class of stochastic volatility models, which include models where possibly neither the data nor the latent volatility process are semimartingales.

Fractional Lévy processes generalize fractional Brownian motion in a natural way. We go a step further and extend the usual fractional Riemann-Liouville kernel to a regularly varying function. We call the resulting stochastic processes generalized fractional Lévy processes (GFLPs) and show that they may have short or long memory increments and that their sample paths may have jumps or not. Moreover, we define stochastic integrals with respect to a GFLP and investigate their second-order structure and sample path properties. A specific example is the Ornstein-Uhlenbeck process driven by a time-scaled GFLP. We prove a functional central limit theorem for such scaled processes with a fractional Ornstein-Uhlenbeck process as a limit process. This approximation applies to a wide class of stochastic volatility models, which include models where possibly neither the data nor the latent volatility process are semimartingales.

Abstract. Multifractional Brownian motions have become popular as flexible models in describing real-life signals of high-frequency features in geoscience, microeconomics, and turbulence, to name a few. The time-changing Hurst exponent, which describes regularity levels depending on time measurements, and variance, which relates to an energy level, are two parameters that characterize multifractional Brownian motions. This research suggests a combined method of estimating the time-changing Hurst exponent and variance using the local variation of sampled paths of signals. The method consists of two phases: initially estimating global variance and then accurately estimating the time-changing Hurst exponent. A simulation study shows its performance in estimation of the parameters. The proposed method is applied to characterization of atmospheric stability in which descriptive statistics from the estimated time-changing Hurst exponent and variance classify stable atmosphere flows from unstable ones.

Within a multicultural society, healthcare professionals (HPs) need to implement specific care pathways to meet the needs of patients with different cultural backgrounds who regularly present themselves in healthcare facilities in Italy. This study intends to examine the experiences and representations lived by HPs who deal with the care and management of foreign immigrant patients living in Italy, with chronic diseases. For this goal, a survey was conducted on a sample of 54 HPs recruited in hospital and outpatient facilities. The survey was analyzed with a quantitative analysis method. The results underlined that it is necessary to provide specific training paths to work with chronic immigrant patients, standardizing the training of medical staff both in hospitals and clinics, and providing for other types of professionals specialized in relations with foreign patients, to respond to all requests from foreign users, and not just healthcare ones. This study proposes a new survey model aimed at obtaining in-depth information on the representation of HPs towards the health and well-being of chronic immigrant patients, to provide concrete answers to the needs of the foreign population, providing for the collaboration of several specialised professionals.

Abstract Motivation Driver (epi)genomic alterations underlie the positive selection of cancer subpopulations, which promotes drug resistance and relapse. Even though substantial heterogeneity is witnessed in most cancer types, mutation accumulation patterns can be regularly found and can be exploited to reconstruct predictive models of cancer evolution. Yet, available methods can not infer logical formulas connecting events to represent alternative evolutionary routes or convergent evolution. Results We introduce PMCE, an expressive framework that leverages mutational profiles from cross-sectional sequencing data to infer probabilistic graphical models of cancer evolution including arbitrary logical formulas, and which outperforms the state-of-the-art in terms of accuracy and robustness to noise, on simulations. The application of PMCE to 7866 samples from the TCGA database allows us to identify a highly significant correlation between the predicted evolutionary paths and the overall survival in 7 tumor types, proving that our approach can effectively stratify cancer patients in reliable risk groups. Availability and implementation PMCE is freely available at https://github.com/BIMIB-DISCo/PMCE, in addition to the code to replicate all the analyses presented in the manuscript. Supplementary information Supplementary data are available at Bioinformatics online.

One of the tasks of modern education is to prepare future specialists for competition. At the same time, the em-pathy and humanistic values of representatives of socionomic professions make them relatively more vulnera-ble to the stress of competition, including the need to regularly maintain their competitive ability. Objective: to study students’ readiness to compete and to develop psychological means of its development. Methods: “The level of competitiveness”, “The level of ability to self-learning and self-education” (V.I. Andreev); correlation analysis. Sample: 46 students studying socionomic professions. Results: The prevalence of students’ average level of competitiveness and ability to self-education is revealed. A set of psychological education measures is developed, contributing to the formation of adequate ideas about competition, about the qualities that hinder self-education and competitiveness, the formation of skills of organization of developmental leisure and self-regulation in stressful situations, the development of productive solutions and the implementation of competi-tive interaction. Available methods are used, recommended for the activities of the psychological service and in the teaching of special courses in psychology.

The present study is a follow-up of a prior study examining a broad range of longitudinal predictors of dimensional positive mental health (PMH) and negative mental health (NMH), using cross-cultural data from the Bochum Optimism and Mental Health (BOOM) study. The present study sought to expand prior findings on positive mental health predictors to a longer longitudinal timeframe. The analysis, specifically, tests our prior model using a third time point, The following positive constructs were examined in relation to later positive mental health: resilience, social support, social rhythm, family affluence, physical health and expectations for fertility. Negative predictors depression, anxiety, and stress were also examined in relation to time 3 positive mental health. Participants included university student samples from Germany (N = 591) and China (N = 8,831). Structural equation modeling was used to examine the effects of predictors on mental health. In China, three of the six salutogenic predictors (social rhythm regularity, positive mental health, resilience) at baseline were predictive of positive mental health at both follow-ups with generally small, but significant effects. Social support at baseline predicted more, and stress and anxiety predicted less positive mental health at follow-up 1, with generally small effects. Depression at baseline predicted less positive mental health at follow-up 2. In Germany, two of the six salutogenic predictors (positive mental health, social support) at baseline were predictive of positive mental health at both follow-ups, with generally small effects. Pathogenic predictors were not predictive of positive mental health at either follow-up. According to multi group analysis, the paths from positive mental health baseline to positive mental health follow-up 1 (FU1) as well as the path positive mental health FU1 to positive mental health follow-up 2 (FU2) were found to differ between Germany and China. All other paths could be seen as equivalent in Germany and China. Results indicate prediction of positive mental health over an extended period of time, and in particular by salutogenic predictors. Pathogenic predictors were also (negatively) predictive of PMH, but with more mixed results, underscoring the differential prediction of PMH from salutogenic and pathogenic factors.

Abstract Irrigation water extracted from the Yellow River plays a key role in water resource management in the Yinchuan Plain (YCP), arid Northwest China. Investigating the soluble matters (ion and gas) of groundwater provides information to explain the unconfined shallow aquifer recharge and groundwater mineralization processes after long-term flood irrigation activity. Environmental tracing with the elements, 2H, 18O, 3H, and CFCs, combining geochemistry using major ions and selected trace elements, was conducted for 43 water samples from September to October 2019 in the YCP. Evaporite and silicate weathering dominate the shallow unconfined groundwater geochemical compositions. Water–rock interactions control the mineralization characteristics regularly along the groundwater flow paths from the southwest toward the northeast. Stable isotopes suggest that Yellow River water and precipitation in winter and/or from Helan Mountainous area are the main recharge sources. The shallow unconfined aquifer mixed young (post-1940) and old (pre-1940) water with young water ratios from 53.1 to 73.5% inferred from the CFC concentrations and 3H activities. Water reinfiltrations extracted from the Yellow River and from the old groundwater are confirmed. Lateral flow recharge for the shallow unconfined aquifer is less indistinctive than that from the water re-infiltration in the plain areas.

Purpose: The study explores the structure of intellectual capital and how it influences firm performance of Kompas 100 Index companies using the VAIC model. Method: As research samples, 29 companies from the Kompas 100 index that were listed on the Indonesian Stock Exchange were employed. The data came from annual reports that were released between 2017 and 2021. A multiple regression analysis was used to create the regression model for this study. Findings: It can be observed that VAIC has a significant positive effect on both ROA and ROE. Based on each component of VAIC, it is clear that HCE, SCE, and CEE have a positive and significant impact on firm performance. By setting spesific targets and regularly monitoring these neasures, businesses can identify areas for improvement and make informed decisions to enhance their firm performance. Novelty: The findings are especially significant for policymakers that want to emphasize the value of Intellectual Capital and create a system for disclosing Intellectual Capital. This study also offers up new paths for future research that will take into consideration the dynamic nature of the relationship between Intellectual Capital and Firm Performance and account for endogeneity. Keywords: Human Capital Efficency; Structural Capital Efficiency; Capital Employed Efficiency; Value Added Intellectual Coefficient

With (Qt)t denoting the stationary workload process in a queue fed by a Lévy input process (Xt)t, this paper focuses on the asymptotics of rare event probabilities of the type P(Q0 > pB, QTB > qB) for given positive numbers p and q, and a positive deterministic function TB. We first identify conditions under which the probability of interest is dominated by the ‘most demanding event’, in the sense that it is asymptotically equivalent to P(Q > max{p, q}B) for large B, where Q denotes the steady-state workload. These conditions essentially reduce to TB being sublinear (i.e. TB/B → 0 as B → ∞). A second condition is derived under which the probability of interest essentially ‘decouples’, in that it is asymptotically equivalent to P(Q > pB)P(Q > qB) for large B. For various models considered in the literature, this ‘decoupling condition’ reduces to requiring that TB is superlinear (i.e. TB / B → ∞ as B → ∞). This is not true for certain ‘heavy-tailed’ cases, for instance, the situations in which the Lévy input process corresponds to an α-stable process, or to a compound Poisson process with regularly varying job sizes, in which the ‘decoupling condition’ reduces to TB / B2 → ∞. For these input processes, we also establish the asymptotics of the probability under consideration for TB increasing superlinearly but subquadratically. We pay special attention to the case TB = RB for some R > 0; for light-tailed input, we derive intuitively appealing asymptotics, intensively relying on sample path large deviations results. The regimes obtained can be interpreted in terms of the most likely paths to overflow.

With (Q t ) t denoting the stationary workload process in a queue fed by a Lévy input process (X t ) t , this paper focuses on the asymptotics of rare event probabilities of the type P(Q 0 &gt; pB, Q T B &gt; qB) for given positive numbers p and q, and a positive deterministic function T B . We first identify conditions under which the probability of interest is dominated by the ‘most demanding event’, in the sense that it is asymptotically equivalent to P(Q &gt; max{p, q}B) for large B, where Q denotes the steady-state workload. These conditions essentially reduce to T B being sublinear (i.e. T B /B → 0 as B → ∞). A second condition is derived under which the probability of interest essentially ‘decouples’, in that it is asymptotically equivalent to P(Q &gt; pB)P(Q &gt; qB) for large B. For various models considered in the literature, this ‘decoupling condition’ reduces to requiring that T B is superlinear (i.e. T B / B → ∞ as B → ∞). This is not true for certain ‘heavy-tailed’ cases, for instance, the situations in which the Lévy input process corresponds to an α-stable process, or to a compound Poisson process with regularly varying job sizes, in which the ‘decoupling condition’ reduces to T B / B 2 → ∞. For these input processes, we also establish the asymptotics of the probability under consideration for T B increasing superlinearly but subquadratically. We pay special attention to the case T B = RB for some R &gt; 0; for light-tailed input, we derive intuitively appealing asymptotics, intensively relying on sample path large deviations results. The regimes obtained can be interpreted in terms of the most likely paths to overflow.

<p><strong><em>Background:</em></strong><em> </em><em>Diabetes Mellitus (DM) causes a decrease in quality of life in all domains. The most often overlooked cause of DM patients is not carrying out physical activity regularly. </em><strong><em>Purpose:</em></strong><em> </em><em>The purpose of this study was to determine the effect of healthy pathways on the quality of life of type 2 D</em><em>M</em><em> patients in the Health Center in Kotabumi North Lampung in 2017.</em><em> </em><strong><em>Methods:</em></strong><em> </em><em>This study used quasi-experimental pre-post test design with a control group. The number of samples consisted of treatment groups and control groups, each group of 22 respondents. The treatment group was the respondents who carried out healthy walks of intervention, then measured the quality of life of patients with type 2 diabetes mellitus, while the control group did not carry out healthy walking activities. Data analysis uses t test dependent. </em><strong><em>Results:</em></strong><em> </em><em>The results showed that there was an effect of healthy pathways on the quality of life of patients with type 2 diabetes mellitus in the health centers in Kotabumi, North Lampung (p = 0.007). <strong>Conclusions</strong></em><strong><em>:</em></strong><em> Healthy paths improve the quality of life for patients with type 2 diabetes, including aspects of physical health, psychological health, social and environmental relations. </em></p><p><strong>Latar Belakang:</strong> Penyakit Diabetes Mellitus (DM) menyebabkan penurunan kualitas hidup disemua domain. Penyebab yang paling sering diabaikan penderita DM adalah tidak melaksanakan aktivitas fisik secara teratur. <strong>Tujuan: </strong>Tujuan penelitian ini untuk mengetahui pengaruh jalan sehat terhadap kualitas hidup penderita DM tipe 2 di Puskesmas wilayah Kotabumi Lampung Utara Tahun 2017. <strong>Metode:</strong> Penelitian ini menggunakan <em>kuasi eksperimen pre post test design </em> dengan kelompok kontrol. Jumlah sampel terdiri atas kelompok perlakuan dan kelompok kontrol masing-masing kelompok 22 responden. Kelompok perlakuan adalah responden yang dilakukan intervensi jalan sehat, kemudian dilakukan pengukuran kualitas hidup penderita DM tipe 2, sedangkan kelompok kontrol tidak melakukan kegiatan jalan sehat. Analisis data menggunakan <em>t </em><em>test dependent</em>. <strong>Hasil:</strong> Hasil penelitian menunjukkan terdapat pengaruh jalan sehat terhadap kualitas hidup penderita DM tipe 2 di Puskesmas wilayah Kotabumi Lampung Utara (p=0,007). <strong>Simpulan:</strong> Jalan sehat meningkatkan kualitas hidup penderita DM tipe 2 meliputi aspek kesehatan fisik, kesehatan psikologis, hubungan sosial dan lingkungan.</p>

AbstractThe sample paths of white noise are proved to be elements of certain Besov spaces with dominating mixed smoothness. Unlike in isotropic spaces, here the regularity does not get worse with increasing space dimension. Consequently, white noise is actually much smoother than the known sharp regularity results in isotropic spaces suggest. An application of our techniques yields new results for the regularity of solutions of Poisson and heat equation on the half space with boundary noise. The main novelty is the flexible treatment of the interplay between the singularity at the boundary and the smoothness in tangential, normal and time direction.

AbstractBy the work of P. Lévy, the sample paths of the Brownian motion are known to satisfy a certain Hölder regularity condition almost surely. This was later improved by Ciesielski, who studied the regularity of these paths in Besov and Besov-Orlicz spaces. We review these results and propose new function spaces of Besov type, strictly smaller than those of Ciesielski and Lévy, in which the sample paths of the Brownian motion almost surely lie. In the same spirit, we review and extend the work of Kamont, who investigated the same question for the multivariate Brownian sheet and function spaces of dominating mixed smoothness.

Abstract In this paper, we investigate the regularity properties and determine the almost sure multifractal spectrum of a class of random functions constructed as sums of pulses with random dilations and translations. In addition, the continuity moduli of the sample paths of these stochastic processes are investigated.

AbstractIn light of recent work on particles fluctuating in linear viscoelastic fluids, we study a linear stochastic partial-integro-differential equation with memory that is driven by a stationary noise on a bounded, smooth domain. Using the framework of generalized stationary solutions introduced in McKinley and Nguyen (SIAM J Math Anal 50(5):5119–5160, 2018), we provide conditions on the differential operator and the noise to obtain the existence as well as Hölder regularity of the stationary solutions for the concerned equation. As an application of the regularity results, we compare to analogous classical results for the stochastic heat equation. When the 1d stochastic heat equation is driven by white noise, solutions are continuous with space and time regularity that is Hölder $$(1/2-\epsilon )$$ ( 1 / 2 - ϵ ) and $$(1/4-\epsilon )$$ ( 1 / 4 - ϵ ) respectively. When driven by colored-in-space noise, solutions can have a range of regularity properties depending on the structure of the noise. Here, we show that the particular form of colored-in-time memory that arises in viscoelastic diffusion applications, satisfying what is called the Fluctuation–Dissipation relationship, yields sample paths that are Hölder $$(1/2-\epsilon )$$ ( 1 / 2 - ϵ ) and $$(1/2-\epsilon )$$ ( 1 / 2 - ϵ ) in space and time.

We study ordinary differential equations (ODEs) with vector fields given by general Schwartz distributions, and we show that if we perturb such an equation by adding an “infinitely regularizing” path, then it has a unique solution and it induces an infinitely smooth flow of diffeomorphisms. We also introduce a criterion under which the sample paths of a Gaussian process are infinitely regularizing, and we present two processes which satisfy our criterion. The results are based on the path-wise space–time regularity properties of local times, and solutions are constructed using the approach of Catellier–Gubinelli based on nonlinear Young integrals.

AbstractWe develop a multilevel Monte Carlo (MLMC)-FEM algorithm for linear, elliptic diffusion problems in polytopal domain $${\mathcal {D}}\subset {\mathbb {R}}^d$$ D ⊂ R d , with Besov-tree random coefficients. This is to say that the logarithms of the diffusion coefficients are sampled from so-called Besov-tree priors, which have recently been proposed to model data for fractal phenomena in science and engineering. Numerical analysis of the fully discrete FEM for the elliptic PDE includes quadrature approximation and must account for (a) nonuniform pathwise upper and lower coefficient bounds, and for (b) low path-regularity of the Besov-tree coefficients. Admissible non-parametric random coefficients correspond to random functions exhibiting singularities on random fractals with tunable fractal dimension, but involve no a-priori specification of the fractal geometry of singular supports of sample paths. Optimal complexity and convergence rate estimates for quantities of interest and for their second moments are proved. A convergence analysis for MLMC-FEM is performed which yields choices of the algorithmic steering parameters for efficient implementation. A complexity (“error vs work”) analysis of the MLMC-FEM approximations is provided.

Abstract Motivated by insurance applications, we propose a new approach for the validation of real-world economic scenarios. This approach is based on the statistical test developed by Chevyrev and Oberhauser ((2022) Journal of Machine Learning Research, 23(176), 1–42.) and relies on the notions of signature and maximum mean distance. This test allows to check whether two samples of stochastic processes paths come from the same distribution. Our contribution is to apply this test to a variety of stochastic processes exhibiting different pathwise properties (Hölder regularity, autocorrelation, and regime switches) and which are relevant for the modelling of stock prices and stock volatility as well as of inflation in view of actuarial applications.

AbstractA system of edge cracks was applied to polished (010) surfaces of K-rich gem-quality alkali feldspar by diffusion-mediated cation exchange between oriented feldspar plates and a Na-rich NaCl–KCl salt melt. The cation exchange produced a Na-rich layer at and beneath the specimen surface, and the associated strongly anisotropic lattice contraction lead to a tensile stress state at the specimen surface, which induced fracturing. Cation exchange along the newly formed crack flanks produced Na-enriched diffusion halos around the cracks, and the associated lattice contraction and tensile stress state caused continuous crack growth. The cracks nucleated with non-uniform spacing on the sample surface and quickly attained nearly uniform spacing below the surface by systematic turning along their early propagation paths. In places, conspicuous wavy cracks oscillating several times before attaining their final position between the neighboring cracks were produced. It is shown that the evolution of irregularly spaced towards regularly spaced cracks including the systematic turning and wavyness along the early propagation paths maximizes the rate of free energy dissipation in every evolutionary stage of the system. Maximization of the dissipation rate is suggested as a criterion for selection of the most probable evolution path for a system undergoing chemically induced diffusion mediated fracturing in an anisotropic homogeneous brittle material.

Nowadays, caves are increasingly being transformed into tourist attractions by constructing paths, electricity, water infrastructure, and the introduction of light, thereby becoming affected by various disturbances that alter their inherent equilibrium. Conservation of these sensitive environments should be a priority from the moment of their opening. All parameters, including the potential changes around artificial lights, such as lampenflora, should be monitored. Lampenflora in show caves in Serbia has been done for several years in the Lazar and Resava caves, of which the Lazar cave was monitored for over 6 years. This work aimed to compare lampenflora of these two caves, considering samples taken in the year 2021 at the beginning and the end of the official tourist season. Artificial light created favorable conditions for the proliferation of phototrophs, and lampenflora developed in both caves. Considering the community type, epiliths and endoliths were present in both localities. The difference is that endoliths in the Lazar Cave covered more significant areas of substratum, constantly spreading, thus posing a more significant threat to cave substratum and structures. One of the problematic genera was Chlorella, which can switch from an autotrophic to a mixotrophic, and finally to a heterotrophic lifestyle, thus making lampenflora dangerous and hard to deal with. Lampenflora in the Lazar Cave was developed over a large area of the cave substratum, while in Resava Cave, it was usually localized near artificial lights. When caves were compared based on phototrophic microorganism composition, using multivariate analysis, all morphological groups of Cyanobacteria (coccoid, simple trichal, and heterocystous) were more related to the Resava cave and Chlorophyta and Bacillariophyta to the Lazar Cave (based on diversity and number of sampling sites on which they are found). In the Lazar and Resava cave, Cyanobacteria dominated at the beginning of the tourist season and Chlorophyta at the end. Mosses were present, too, with the difference that the moss protonema was more characteristic of Lazar Cave in many places. In contrast, developed mosses were frequently found in Resava Cave near reflectors. In addition to the analysis of phototrophic microorganisms, ecological parameters, primary production, and biofilm parameters were measured, showing seasonal or sampling site variations. We hope that monitoring will be performed more regularly in the future and that it will include a more significant number of show caves for their conservation.

Artiklis analüüsitakse nõukogudeaegsete ajakirjanike tsensuurimeenutusi. Analüüsi aluseks on 57 eluloolist intervjuud aastatest 2015–2016. Põhiküsimus on, kuidas tõlgendavad ajakirjanikud nõukogude tsensuuri veerand sajandit pärast selle lõppemist. Uurimismeetodina on kasutatud raamistamise analüüsi (frame/framing analysis). Ajakirjanikud raamistasid tsensuuritemaatikat eelkõige neljal moel: ajakirjanik kui tsensuuriteadlik tegutseja; salastatud tsensuur; vähetähtis tsensuur; totter tsenseerimine. Intervjueeritud rõhutasid enese teadlikkust süsteemist ning leidsid, et kogenud ja tark ajakirjanik leppis tsensuuriga kui paratamatusega ja oskas keelde ennetavalt arvestada. Nad ei tõlgendanud seda aga mitte tsensuurile allumisena, vaid tsensuurist eemalseismisena. This article studies Soviet era journalists’ recollections of censorship. The analysis is based on 57 face-to-face biographical interviews with press, radio and television journalists which were conducted in 2015–2016 (the total length of interviews is 99 hours, 5% deal with the topic of censorship). The main question of the article is how do journalists interpret Soviet censorship twenty-five years after its end. Firstly, what do they remember or recall. Secondly, to which extent can these recollections be considered a source of truth, and how do they deviate from the truth. Thirdly, how do journalists interpret censorship and their relations with censorship, in particular, their relations with resistance to censorship. The method of frame analysis is used. Soviet censorship was designed to regulate all spheres of life but, at the same time, to be invisible (according to the Constitution, freedom of speech and of the press was guaranteed to Soviet citizens). The complex and intertwined censorship system can be divided into two parts: ideological control and concealment of state secrets. The ideological control, or party censorship was based on ideological correctness, defined and controlled by the Communist Party and the KGB (Committee for State Security). Guidance on what is ideologically dangerous and forbidden was given by the Central Committee of the Estonian Communist Party through its propaganda and agitation department. The rules were not always precise and specific, many guidelines were oral and not documented. Party censorship was executed on the individual publication level by editors-in-chief, whose task was to ensure that the correct ideological line was followed. State secrets were the responsibility of Glavlit, whose task was to check that the press did not disclose military, state or economic secrets. Their work was based on regularly updated lists of data which were forbidden to be published. For example, in 1976, the list of banned data consisted of 176 pages. The existence and contents of the list of banned data was a secret, only a limited circle of accountable persons (including editorial leaders, but not lower ranking journalists) were allowed to know its content. Four main conclusions can be drawn based on the analysed interviews. The journalists’ recollections of censorship cannot be regarded as objective truth. Recollections are contradictory both in minor details and in fundamental issues. Based on the recollections, no definite conclusions can be drawn about the entire censorship system, but they can be used to understand how specific bans functioned and specific censors acted. Journalists preferred to interpret censorship narrowly, as a ban on publishing state secrets. Ideological party control, exercised by editors-in-chief and party functionaries, was interpreted not as a censorship, but as a routine part of the Soviet editing process. In doing so, the journalists distanced themselves from censorship and the censorship process. Journalists placed themselves and the editors outside of the censorship system. Censorship was performed by “others”, in particular, by Glavlit officials and the persons who had to communicate with these officials. Journalists framed censorship in four ways: a journalist as a wise, censorship-conscious agent; secretive censorship; unimportant censorship; ridiculous bans. Journalists focused on self-agency, they did not interpret themselves as the victims of circumstance, but as skilfully coping professionals who knew the system and chose ‘doublethink’ to deal with it. Thus the self-superiority dominated – journalists set themselves above censorship. In addition, a number of journalists described the Soviet censorship in a neutral way, without expressing a clear negative or positive attitude towards it and without taking a side. They described, explained and exemplified the bygone phenomenon and the remote past. The interviewed journalists framed the experience of the Soviet-era censorship differently from how the editors of cultural magazines have done in their memoires. Among the editors of cultural magazines, the pathos of resistance dominated, while the so-called regular journalists among the studied sample represented the pathos of adaptation. The interviewed journalists emphasized their awareness of the system, its way of functioning and its boundaries. They found that an experienced and wise journalist accepted censorship as an inevitability of Soviet life and was able proactively to take bans into account. They did not, however, interpret it as being subjected to censorship, but as avoiding censorship. Thus, journalists distanced themselves from the scale of adaptation/resistance to censorship and described themselves as bystanders.

Renew is an awkward word. Its prefix seems to make its idea of something 'new' impossible. And everyday experience further underlines the contradiction. My first memory of using the word 'renew' was related to the anxiety of library overdue books: renewing those books was a pragmatic way to avoid the impending fines. This is a useful starting point for pondering any cultural moment of renewal. Renew describes the impetus towards change while acknowledging the past's weighted effect on producing any transformation. It articulates a challenged continuity rather than a break or discontinuity with a particular past. Where I would like to take this idea of renewal is into the realm of cultural studies and its continuing intellectual project through two efforts or essays. Essay 1: Recombinant Culture There are no doubt many ways to characterise the value of cultural studies. What I want to emphasise here is how cultural studies worked to transform the basic conceptualisation of culture itself. These are familiar paths but to identify some of the principal intellectual traits for rethinking and fundamentally renewing the definition of culture: the contested terrain of the popular; the hegemonic restructuring of culture through winning and building of consent as a moving and transforming force; and the concentration on the making of the "other" and the "other's" process of piecing together cultural sense Through all these paths the real power of cultural studies has been its ability to migrate into disciplines and work to renew their internal directions through challenge. Although naturalised homes for cultural studies have been found in media and communication programmes, this has been partly possible through their roughly contemporaneous emergence and partly through this sister intellectual project's capacity to deal seriously with popular culture. Where renewal has been more brazenly articulated is in sites such as geography and its turn to culture and space issues, English and its transformation of its object of study, or musicology with its rereading of popular music and its cadence of cultural meaning and, to a lesser extent sociology and history. What cultural studies has been is a migrating source of renewal across the humanities and social sciences. The core of cultural studies, which is much more difficult to define except in a listing of key concepts and strategies of cultural engagement through intellectual work (of which I provided only a partial list above), has not necessarily gone through this same pattern of renewal over the last 20 years. What I would like to propose here is a moment of rethinking what constitutes cultural studies. This goes beyond Richard Johnson's historical reading of what is cultural studies. Using a new metaphor to describe its approach may begin this renewal of the core. Cultural studies can be rearticulated in terms of its capacity at recombining. As I have indicated, cultural studies has worked to juxtapose its redefinitions of the cultural against and over these 19th century disciplines and has produced quite dramatic shifts in approaches within the disciplines and across the disciplines. Recombining then is the intellectual practice of cultural studies. It generally analyses the form of recombinations that emerge on the contemporary scene. Some have labelled this process hybridisation -- the work of Iain Chambers and Lydia Curti identifies the movements through borders and boundaries both physical and psychical. As a practice, cultural studies can debate and discuss the moments of rupture of the continuous (what previous approaches might call the ideological and naturalised veneer of historical continuity), but with the comprehension of how the rupture negotiates with the past and its ideological weight. In other words, cultural studies' practice is one of perpetual renewal through its study of recombinant culture. These moments of recombination can be seen in the structure of identity and cultural politics, where the stable structures of identity serve as much as political tactics as structures. Most visibly, recombinant culture can be the way to understand how new technologies are used and reformed through use by different cultural communities. Popular music provides a model for this continuous flow of recombining for both renewal and a shifted cultural significance. Sounds are sampled; past songs are layered into a significantly different music and use in current dance music. Recombinant culture may also be studied from the perspective of cultural industries and their efforts to incorporate new technologies into different forms in order to reconstitute audiences in ways that in their distinctiveness produce value that is exchangeable as capital. Understanding the constant negotiation of recombinant culture is where cultural studies should relocate its energies and renew its vitality. Essay 2: Refocussing on Cultural Production One of the successes of cultural studies is its well-developed reading of the practices of reception. The active audience approach has led to understanding how audiences use and contextualise cultural forms. Specifically studies in television, popular music and, to a lesser degree, film have benefitted from this rereading of popular culture and audiences. Clearly underdeveloped in cultural studies is an analysis of production. Yet the massive work on the active audience approach is fundamentally a study of cultural production, albeit in the terminology of reception. What is embedded in the active audience reading of cultural forms is the audience's will to produce the text. This reproduction of the text by the audience not only transforms the text, but also points to the very desire (by cultural studies' research itself in the same way that the researcher's reading of a subculture's political and cultural will was refracted through sartorial style and a cultural politics of street appropriation) for the will to produce in the audience. There is a moment in our recombinant culture that certain technologies have intensified the will to produce, if not production itself. The Internet and the World Wide Web have provided cultural studies a clear shift towards a production ethos that has altered the formal boundaries of what constitutes production. The user of the Internet actively plays the role of producer and audience, not just in terms of a heightened pattern of interactivity but in the regularity and routineness with which Websites appear as part of the general system of cultural production. Because all Websites are distributed and disseminated in one system or network the delineations that used to give television networks their nearly exclusive voice and image of authority are not as easily made via the Internet. This moment of production flux and the cultural politics it has generated is already contested as large media corporations work to differentiate content and "quality" so that websites are hierarchised into different registers of cultural value. What I am arguing for here is a renewal of study that now looks at a different starting point in the cycles of production and consumption for cultural studies. Production in this recombinant culture always implies a process of reception and recontextualisation of the past meanings into current objectives and directions. Cultural studies needs to investigate this current blending of production and consumption more vigorously. For instance, how does Napster shift the play of the production outwards into a myriad of possible recombining producer/consumers who make their music available for others? How is the large music publisher Bertelsmann engaging in a process of capitalising in some way on this process of dissemination through their negotiations with Napster? We are seeing enacted in this one case the changing landscape of cultural production and cultural consumption where the product, the property and the service are no longer clearly defined in either industrially or culturally agreed-upon standards. New media culture in general is operating on different criteria of cultural production and cultural consumption: products seem to be continually in process and in that process include their consumers into the process of production. This is clearly evident in the development of computer games as they include their core "audience" in transforming and improving their "product". The digitalisation of cultural forms has permitted the development of "soft-products": that is, products that can be changed and recombined and are therefore not so easily end-products but as entities are continually in process. Because cultural studies has such a well-developed understanding of the process of the transformation of meaning through its study of active reception, it is particularly valuable in interpreting how this recombinant culture is operating in and through new technologies. In a sense, cultural studies can be deployed in making sense of this transformed cultural economy. Through a shift in focus from consumption to production (but fundamentally working with the same insights about cultural meaning, activity and production), the intellectual project of cultural studies can successfully renew itself. Citation reference for this article MLA style: P. David Marshall. "Renewing Cultural Studies." M/C: A Journal of Media and Culture 3.6 (2000). [your date of access] <http://www.api-network.com/mc/0012/studies.php>. Chicago style: P. David Marshall, "Renewing Cultural Studies," M/C: A Journal of Media and Culture 3, no. 6 (2000), <http://www.api-network.com/mc/0012/studies.php> ([your date of access]). APA style: P. David Marshall. (2000) Renewing Cultural Studies. M/C: A Journal of Media and Culture 3(6). <http://www.api-network.com/mc/0012/studies.php> ([your date of access]).