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In this introduction, we set out the central themes of the special issue. It concentrates on imperfect function-form mappings, and discusses several cases in which specific perspectival meanings are not fully predictable on the basis of a perspectivizing grammatical construction alone. We distinguish two kinds of form-function mismatches: (1) perspective-persistent phenomena, i.e. grammatically signaled deictic and/or cognitive perspective shifts which are not realized in interpretation, and (2) irregular perspective shifts, which involve either grammatically un(der)specified shifts or grammatically signaled shifts that are interpreted as mixing multiple sources of deictic and/or cognitive perspective (‘multiple-perspective constructions’). We briefly discuss and contextualize each of the contributions, and highlight their central findings.

We study the iso-manifold persistence in formulism. We employ a quasilinear iterative scheme to show that the majority of unperturbed tori give rise to invariant tori of the perturbed system starting from the same Riemannian manifold and keep the ratio of certain components of the respective frequencies. We also consider the iso-manifold Melnikov persistence.

In recent years, topological data analysis (TDA) has become a popular tool for studying 3D point clouds. Persistent homology is one of the most important tools of TDA, as it can extract the topological features hidden in a point cloud. However, the time-consuming computation of persistence diagrams severely limits the application of TDA. In this study, we propose an end-to-end TopologyNet that directly fits the output of the topological representations from the input point cloud data. TopologyNet significantly reduces the computation time of producing topological representations compared with the traditional pipeline, while maintaining a small approximating error in practical instances. For point cloud generation, we use TopologyNet as a topological branch to improve the performance of a point cloud autoencoder. Moreover, the additional topological features are used in a latent generative adversarial network to produce new point clouds.

In forensic science, knowledge and understanding of material transfer and persistence is inherent to the interpretation of trace evidence and can provide vital information on the activity level surrounding a crime. Detecting metal ions in fingermark residue has long been of interest in the field of forensic science, due to the possibility of linking trace metal ion profiles to prior activity with specific metal objects (e.g. gun or explosive handling). Unfortunately, the imaging capability to visualise trace metal ions at sufficient spatial resolution to determine their distribution within a fingermark (micron level) was not previously available. Here, we demonstrate for the first time transfer and persistence of metals in fingermarks, at micron spatial resolution, using synchrotron sourced x-ray fluorescence microscopy. Fingermarks were taken before and after brief handling of a gun barrel, ammunition cartridge case and party sparkler to demonstrate the transfer of metals. The results reveal increased metal content after contact with these objects, and critically, a differential pattern of metal ion increase was observed after handling different objects. Persistence studies indicate that these metals are removed as easily as they are transferred, with a brief period of hand washing appearing to successfully remove metallic residue from subsequent fingermarks. Preliminary work using x-ray absorption near edge structure spectroscopic mapping highlighted the potential use of this technique to differentiate between different chemical forms of metals and metal ions in latent fingermarks. It is anticipated that these findings can now be used to assist future work for the advancement of trace metal detection tests and fingermark development procedures

For years Georgia's HOPE Scholarship program provided full tuition scholarships to high-achieving students. State budgetary shortfalls reduced its generosity in 2011. Under the new rules, only students meeting more rigorous merit-based criteria would retain the original scholarship covering full tuition, now called the Zell Miller Scholarship, with other students seeing aid reductions of approximately 15 percent. We exploit the fact that two of the criteria were high school grade point average and SAT/ACT score, which students could not manipulate when the change took place. We compare already-enrolled students just above and below these cutoffs, making use of advances in multi-dimensional regression discontinuity, to estimate effects of partial aid loss. We show that, after the changes, aid flowed disproportionately to wealthier students and find no evidence that the financial aid reduction affected persistence or graduation for these students. The results suggest that high-achieving students, particularly those already in college, may be less price-sensitive than their peers.

Satellite-derived soil moisture (SM) products have become an important information source for the study of land surface processes in hydrology and land monitoring. Characterizing and estimating soil memory and persistence from satellite observations is of paramount relevance, and has deep implications in ecology, water management, and climate modeling. In this work, we address the problem of SM persistence estimation from microwave sensors using several autocorrelation metrics that, unlike traditional approaches, build on accurate estimates of the autocorrelation function from nonuniformly sampled time series. We show how the choice of the autocorrelation estimator can have a dramatic impact on the SM persistence metrics derived thereof, particularly given the nonuniform nature of satellite observations, yet this fact has been overlooked to a large extent in literature. We give empirical evidence of performance using ground-based SM measurements, as well as L-band Soil Moisture and Ocean Salinity (SMOS) and C-band [Advanced Microwave Scanning Radiometer-2 (AMSR2), Advanced Scatterometer (ASCAT)] remotely sensed SM data. Experiments along transects allow us to scrutinize the inter-method consistency and the spatial-temporal characteristics of autocorrelation estimators. This motivates the introduction of novel measures of spatial-temporal autocorrelation and allows us to retrieve improved persistence estimates. Results over the Iberian Peninsula indicate the SM persistence patterns captured by L- and C-band microwave sensors over semiarid regions exhibit spatially concurrent patterns of persistence and support their combination in long-term data records. We conclude that accounting for the nonuniform nature of the satellite time series using robust autocorrelation estimations allows providing improved measures and spatial descriptions of SM persistence.

This study aims to investigate the relationship of the persistence of metopic suture (PMS), frontal sinus volume (FSV), and olfactory fossa depth (OFD).Tomography scans of 1,603 patients aged 18-65 years were evaluated for the presence of PMS. In the study, 74 PMS cases and 74 controls were included. The appearance of each individual's frontal sinus was classified as aplasia, hypoplasia, or normal. Two observers independently measured the lateral lamella length (LLL), OFD, and FSV. Interobserver agreement was evaluated with the intraclass correlation coefficient (ICC) and Cohen's kappa coefficient (κ).The prevalence of PMS was found to be 4.99% [95% confidence interval (CI): 4.03-6.17]. The PMS group had five times higher hypoplasia/aplasia than the controls (52.70%, 95% CI: 41.48-63.66 and 10.81%, 95% CI: 5.58-19.91, respectively; p0.001). An "almost perfect" agreement was detected among observers for the frontal sinus appearance classification: κ=0.807, p0.001. The ICC of continuous measurements for OFD, LLL, and FSV, respectively, presented "excellent" reliability: 0.956, 0.958, and 0.981, with p0.001 for each. LLL was shorter, OFD was shallower, and FSV was smaller in the PMS group than the control group (p0.001). There was a moderate positive correlation between OFD, LLL, and FSV (r=0.306, r=0.302).This study interprets that the presence of PMS is related frontal sinus development and volume. With PMS, a smaller FS, shorter lateral lamella, and shallower olfactory fossa may be expected.Bu çalışma, persistan metopik sütür (PMS) ile olfaktör fossa derinliği (OFD), ve frontal sinüs volümü (FSV) arasındaki ilişkiyi araştırmayı amaçlamaktadır.Yaşları 18-65 arasında değişen 1.603 hastanın tomografileri PMS varlığı açısından değerlendirildi. Yetmiş dört PMS olgusu ve 74 kontrol çalışmaya dahil edildi. Her bireyin frontal sinüs görünümü aplazi, hipoplazi veya normal olarak sınıflandırıldı. Lateral lamella uzunluğu (LLU), OFD ve FSV ölçümleri iki gözlemci tarafından bağımsız olarak yapıldı. Gözlemciler arası uyum değerlendirilirken, sürekli değişkenler için sınıf içi korelasyon katsayısı (ICC) ve Cohen’s kappa katsayısı (κ) kullanıldı.PMS prevalansı %4,99 [güven aralığı (GA) %95: 4,03-6,17] olarak bulundu. Hipoplazi/aplazi, PMS grubunda kontrol grubuna göre beş kat daha fazlaydı (sırasıyla %52,70; GA %95: 41,48-63,66 ve %10,81; GA %95: 5,58-19,91, p0,001). Frontal sinüs görünüm sınıflandırması için gözlemciler arasında “mükemmel” bir uyum tespit edildi: κ=0,807, p0,001. OFD, LLU ve FSV için ICC “mükemmel” güvenilirlik sundu: Her biri için sırasıyla 0,956, 0,958 ve 0,981 ve p0,001. PMS grubunda, LLU daha kısaydı, OFD daha sığdı ve FSV, kontrol grubuna göre daha küçüktü (her biri için p0,001). OFD, LLU ve FSV arasında orta derecede pozitif korelasyon vardı (r=0,306, r=0,302).Bu çalışmanın sonucunda, PMS’nin frontal sinüs gelişimi ve volümü ile ilişkili olduğu bulunmuştur. PMS varlığında daha küçük bir FS, daha kısa lateral lamella ve daha az derin olfaktör fossa beklenebilir.

Climate change has been and will be accompanied by widespread changes in surface temperature. It is clear that these changes include global-wide increases in mean surface temperature and changes in temperature variance that are more regionally-dependent1–3. It is less clear whether they also include changes in the persistence of surface temperature. This is important as the effects of weather events on ecosystems and society depend critically on the length of the event. Here we provide an extensive survey of the response of surface temperature persistence to climate change over the twenty-first century from the output of 150 simulations run on four different Earth system models, and from simulations run on simplified models with varying representations of radiative processes and large-scale dynamics. Together, the results indicate that climate change simulations are marked by widespread changes in surface temperature persistence that are generally most robust over ocean areas and arise due to a seemingly broad range of physical processes. The findings point to both the robustness of widespread changes in persistence under climate change, and the critical need to better understand, simulate and constrain such changes. A survey of climate change simulations from different models indicates widespread changes in surface temperature persistence under global warming that may be attributable to a broad range of physical processes.

In this paper we develop some KAM techniques to prove the persistence of lower dimensional elliptic-type degenerate invariant tori with prescribed frequencies in Hamiltonian systems. The proof is based on a formal KAM theorem, which allows us to solve the equation of equilibrium points and choose the parameter of small divisors after the KAM iteration, instead of in each KAM step. The proof is also based on the Leray–Schauder continuation theorem, which insures the existence of a path of real roots of an approximating odd-order real polynomial which depends continuously on parameters. This result is very important for us to tackle the Melnikov condition in the elliptic-type degenerate case.

In this paper, we develop a rumor spreading model by introducing white noise into the model. We establish sufficient conditions for the existence and uniqueness of an ergodic stationary distribution of the positive solutions to the stochastic model by constructing a suitable stochastic Lyapunov function, which provides us a good description of persistence. Finally, we provide some numerical simulations to illustrate the analytical results.

In this paper, we investigate the relationship between upper ocean heat content (OHC) and El Niño–Southern Oscillation (ENSO) sea surface temperature (SST) anomalies mainly using the neutral recharge oscillator (NRO) model both analytically and numerically. Previous studies showed that spring OHC, which leads SST by 6–12 months, represents a major source of predictability for ENSO. It is suggested that this seasonality is caused by the seasonally varying growth rate in SST anomalies. Moreover, a shortened ENSO period will lead to a reduced SST predictability from OHC, with the most significant decrease occurring in the latter half of the calendar year. The cross-correlation relationship between OHC and ENSO SST anomalies is further identified in the damped and self-excited version of the recharge oscillator model. Finally, we suggest that the seasonal growth rate of ENSO anomalies is the cause of the seasonality in the effectiveness of OHC as a predictor in ENSO forecasting, particularly as it relates to the boreal spring persistence barrier and associated spring predictability barrier. We also explain the shorter lead time between spring OHC and ENSO SST anomalies after the turn of the twenty-first century in terms of the apparent higher frequency of the ENSO period.

Tree-ring width is one of the most widely used proxy in paleoclimatological studies. Due to various environmental and biological processes, however, the associated reconstructions often suffer from overestimated low-frequency variability. In this study, a new correction approach is proposed using fractional integral techniques that corrects for the overestimated long-term persistence in tree-ring width based hydroclimatic reconstructions. Assuming the high frequency interannual climate variability is well recorded by tree rings, the new approach is able to (i) extract the associated short-term forcing signals of various climate conditions from the reconstructions, and (ii) simulate the long-term impacts of these short-term forcings by setting a proper fractional integral order in the fractional integral statistical model (FISM). In this way, the overestimated long-term persistence, as well as the associated low-frequency variability in tree-ring width based reconstructions can be corrected. We apply this approach to a recently published dataset of precipitation field reconstructions over China covering the past half millennium and removed the redundant, non-precipitation related long-term persistence. Compared to the original reconstruction with multi-century long-term dry conditions in western China, the corrected reconstruction considerably shortened the wet/dry periods to decadal scales. In view of the widespread non-climatic/mixed-climatic signals in tree-ring widths, this new approach may serve as a useful post-processing method to reconsider previous reconstructions. It may even be combined with the current detrending approaches by upgrading the pre-whitening methods.

In this paper, we will consider the wave-breaking mechanism and persistence property of the solution for the weakly dissipative shallow water equation. A wave breaking will arise as soon as the initial value decay faster than the solitary waves at infinity. Therefore, the wave-breaking phenomena is studied by three different methods we provided, which extends the information of this equation. Since the presence of the weakly dissipative term, the equation loses the conservation law $$E=\int _{\mathbb {R}}u^2+u_x^2\mathrm{d}x$$ . This difficulty has been solved by establishing the energy inequality. The main idea of the first two methods is to construct the Riccati-type differential inequality to show that the solution of the equation blows up in finite time. The last method depends on the introduction of two families of Lyapunov functions. In addition, we exhibit the persistence results of the solution in weighted $$L^p$$ -spaces.

Traffic accidents involve great costs both at an economic and a human level. This demands that governments implement strategies to reduce their number and impact. The knowledge of the nature of the phenomenon through the study of time series of accidents enables the design of suitable policies for the desired objectives to be achieved. Thus, this paper deals with the analysis of the statistical properties of the number of road accidents on Spanish roads by using time series techniques based on the concept of fractional integration. The results indicate that the series examined display very low degrees of persistence, with the orders of integration being around 0 and thus showing a short memory pattern. This implies that shocks will be transitory, disappearing fast, and requiring strong policy measures in the case of positive shocks that reduce the number of deaths if we want to maintain that effect in the long run. pre-print 1174 KB

One simple but relatively neglected solution to the notorious coincidence puzzle of the statue and the piece of clay claims that the property of being a statue is a phase sortal property that the p...

International audience; The paper formulates the concept of persistence of excitation for discrete-time linear switched systems, and provides sufficient conditions for an input signal to be persistently exciting. Persistence of excitation is formulated as a property of the input signal, and it is not tied to any specific identification algorithm. The results of the paper rely on realization theory and on the notion of Markov-parameters for linear switched systems.

Binary mixtures of semiflexible polymers with the same chain length, but different persistence lengths, separate into two coexisting different nematic phases when the osmotic pressure of the lyotropic solution is varied. Molecular Dynamics simulations and Density Functional Theory predict phase diagrams either with a triple point, where the isotropic phase coexists with two nematic phases or a critical point of unmixing within the nematic mixture. The difference in locally preferred bond angles between the constituents drives this unmixing without any attractive interactions between monomers.

Record-breaking rainfall occurred over East Asia during the summer of 2020. However, in which aspect the summer of 2020 can be differentiated from the other years remains to be quantified. To this end, this study employs Markov chain analysis to quantify summer rainfall variability over East Asia using three Markov descriptors for heavy precipitation events of over 10 mm day−1: frequency, persistence, and entropy (i.e., irregularity). It is found that the heavy rainfall during the summer of 2020 can be attributed to an anomalously high frequency of rainfall in the central China and Japan and greater rainfall persistence over eastern China and Korea. Empirical orthogonal functions (EOFs) are used to analyze interannual variation in the descriptors using a few primary modes. For the summer 2020 period, the first and second modes for frequency account for the enhanced frequency over central China, and this is linked to sea surface temperature anomalies over the North Pacific, the equatorial eastern Pacific, and tropical Indian Ocean. For persistence, the first mode dominates the anomalous rainfall persistence observed during the summer of 2020. Similar but weak behavior can be also seen by the modes for entropy.

In this work, we investigate some qualitative properties of a stochastic dynamical model for tuberculosis with case detection. Using appropriately formulated stochastic Lyapunov functions, we derive sufficient conditions for the existence (and uniqueness) of an ergodic stationary distribution of the positive solutions of the model, guaranteeing persistence of the disease in the presence of case detection. We also obtained conditions that will allow for the eradication of the disease from the population. Using numerical simulations, we were able to illustrate the analytical results obtained herein.

Knowledge of the mechanisms governing transfer, persistence, and recovery of trace evidence, together with background prevalence in the population of interest, and other task relevant information, is key for the forensic interpretation and reconstruction of what happened at the activity level. Up to now, this informational "toolkit" has largely been developed through empirical forensic studies on specific trace materials such as glass, textile fibers, and soil. Combined with the identified systemic siloing between disciplines, while valuable, such research tends to be very material-dependent, introducing specific parameters and interpretations that may have actually impeded the recognition of underlying foundational factors applicable to most material types. In Australia, there has been a renewed interest in developing a discipline-independent framework for the interpretation and/or reconstruction of trace evidence to interpret specific circumstances in casework. In this paper, we present a discipline agnostic "way of thinking" that has been anchored in foundational science underpinning the trace evidence discipline. Physical and mechanical material properties such as material geometry and surface topography, strength, stiffness, and hardness collectively influence contact interactions through underlying friction, wear, and lubrication cause and effect mechanisms. We discuss how these fundamental factors and parameters stemming from materials science and tribology may be adopted and adapted by forensic practitioners and researchers to contribute to a better understanding of transfer, persistence, and recovery mechanisms irrespective of evidence discipline and material type. Examples are provided to demonstrate the practical significance to real-life casework and academic research.

Purpose The purpose of this paper is to investigate the effects of irregular unsettling on the smoking model in form of the stochastic model as in the deterministic model these effects are neglected for simplicity. Design/methodology/approach In this research, the authors investigate a stochastic smoking system in which the contact rate is perturbed by Lévy noise to control the trend of smoking. First, present the formulation of the stochastic model and study the dynamics of the deterministic model. Then the global positive solution of the stochastic system is discussed. Further, extinction and the persistence of the proposed system are presented on the base of the reproductive number. Findings The authors discuss the dynamics of the deterministic smoking model form and further present the existence and uniqueness of non-negative global solutions for the stochastic system. Some previous study’s mentioned in the Introduction can be improved with the help of obtaining results, graphically present in this manuscript. In this regard, the authors present the sufficient conditions for the extinction of smoking for reproductive number is less than 1. Research limitations/implications In this work, the authors investigated the dynamic stochastic smoking model with non-Gaussian noise. The authors discussed the dynamics of the deterministic smoking model form and further showed for the stochastic system the existence and uniqueness of the non-negative global solution. Some previous study’s mentioned in the Introduction can be improved with the help of obtained results, clearly shown graphically in this manuscript. In this regard, the authors presented the sufficient conditions for the extinction of smoking, if Originality/value This study is helpful in the control of smoking throughout the world.

In this paper, we consider a two-dimensional discrete-time predator–prey model that was recently developed in Ackleh et al. [Persistence and stability analysis of discrete-time predator-prey models...

Reaction systems are a model of interactive computation, where the interaction between a system — itself built up of a number of reactions — and its environment is modelled through context sequences provided by the environment. The standard execution semantics of reaction systems is synchronous, i.e., at each computational step all the enabled reactions are executed. In this paper, we ‘de-synchronise’ such an execution model by allowing only a subset of enabled reactions to be executed. We then study the resulting asynchronous model assuming two fundamental execution policies. The first one allows any subset of reactions to be executed, and the second one draws each subset from a pre-defined pool. We also introduce and discuss the notion of persistence of reactions and sets of reactions in the resulting models of asynchronous reaction systems. In particular, we demonstrate that reaction persistence can be implemented.

SUMMARYFor many machine learning problems, there are sufficient data to train a wide range of algorithms. However, many geoscience applications are challenged with limited training data. Seismic petrophysical classification, mapping seismic data to litho-fluid classes, is one of these examples because the training data labels are based on data gathered from wells. Supervised machine learning algorithms are prone to overfitting in scarce training data situations, but semisupervised approaches are designed for these problems because the unlabelled data are also used to inform the learning process. We adopt label propagation (LP) and self-training methods to solve this problem, because they are semisupervised methods that are conceptually simple and easy to implement. The supervised method we consider for comparison is the popular extreme gradient boosting (XGBoost) classifier. The data set we use for our study is one we generate ourselves from the SEG Advanced Modelling (SEAM) Phase 1 model. We first synthesize seismic data from this model and then perform pre-stack seismic inversion to recover seismic attributes. We formulate a classification problem using the seismic attributes as unlabelled data, with training labels from a single well. The benefit of this being a synthetic problem is that we have full control and the ability to quantitatively assess the machine learning predictions. Our initial results reveal that the inherent depth-dependent background trends of the input attributes produce artefacts in each of the machine learning predictions. We address this problem by using a simple median filter to remove these background trends. The predictions using the detrended inputs improve the performance for all three algorithms, in some cases on the order of 10 to 20 per cent. XGBoost and LP perform similarly in some situations, but our results indicate that XGBoost is rather unstable depending on the attributes used. However, LP coupled with self-training outperforms XGBoost by up to 10 per cent in some instances. Through this synthetic study, our results support the premise that semisupervised algorithms can provide more robust, generalized predictions than supervised techniques in minimal training data scenarios.

Marine dissolved organic matter (DOM) contains more carbon than the combined stocks of Earth’s biota. Organisms in the ocean continuously release a myriad of molecules that become food for microheterotrophs, but, for unknown reasons, a residual fraction persists as DOM for millennia. In this Perspective, we discuss and compare two concepts that could explain this persistence. The long-standing ‘intrinsic recalcitrance’ paradigm attributes DOM stability to inherent molecular properties. In the ‘emergent recalcitrance’ concept, DOM is continuously transformed by marine microheterotrophs, with recalcitrance emerging on an ecosystems level. Both concepts are consistent with observations in the modern ocean, but they imply very different responses of the DOM pool to climate-related changes. To better understand DOM persistence, we propose a new overarching research strategy — the ecology of molecules — that integrates the concepts of intrinsic and emergent recalcitrance with the ecological and environmental context. Marine dissolved organic matter can persist for millennia, but the reasons for this phenomenon are unknown. This Perspective describes and compares two concepts — intrinsic and emergent recalcitrance — explaining marine organic matter persistence.

Elements of settlement spatial layout (physical aspect) and community’s social-cultural life with any rites (non-physical aspect) are still performed by some people in Baluwarti Settlement until today, leading to a distinctive peculiarity. It is this peculiarity that makes Baluwarti Settlement environment located inside the court (palace) different from other settlements (outside the court) in Surakarta. Considering the qualitative research paradigm and historical reading method, this research could find out that the spatial layout concept of Baluwarti Settlement namely Tri Hanakara. In which the kings reigning after Paku Buwana III constructed this Baluwarti settlement to forward the previous King’s wish.

In this article, we study the noise-induced dynamics of the tumor-immune system. A stochastic system is considered by perturbing white noise in a deterministic system. Positivity and boundedness of the solution are established in the stochastic system. The threshold for stochastic weak persistence in mean is derived. We also obtain parametric conditions of stochastic permanence in mean. We justify the extinction of tumor burden with the increase of environmental noise strength. Finally, numerical simulations are performed and validate the analytical findings with proper biological implications.

We study how a rate of environmental change affects stability and persistence of an ecological community. Using an explicit rate of change in the environmental parameters of a spatially coupled ecological system, we study the rate-dependent responses associated with extinction of a metacommunity. Our results elucidate various scenarios of rate-induced extinction (R-tipping) such as tipping through increasing amplitude of oscillations, tipping through synchronized dynamics, and tipping through tracking unstable states. Further, we show rate-dependent delayed responses away from bifurcation points, but with tracking unstable states. Our results emphasize that the rate of environmental change can reveal the unexpected extinction dynamics which may not be predicted from stable equilibrium states and bifurcation points of the system. Thus, our results illustrate the importance of rate-dependent responses to understand stability and persistence of an ecological system.

This study investigates the effect of oil price shocks on the inflation persistence of the top ten (10) oil-exporting and oil-importing countries. The study employs the recently developed fractional cointegration vector autoregressive (FCVAR) approach. It accounts for the role of monetary policy framework and exchange rate regime. It also tests and accounts for oil price asymmetry. The results show that inflation rate persistence of oil-exporting and oil-importing countries does not increase due to oil price shocks suggesting that the monetary policy of these countries accommodates oil price shocks, and may not necessarily be changed due to oil price shocks. This holds for countries operating floating regimes and inflation targeting, and those operating pegged regimes and non-inflation targeting monetary policy framework. The monetary policy of oilimporting countries appears to accommodate oil price shocks. As failure to account for oil price asymmetry tends to exaggerate inflation persistence for both oil-exporting and oil-importing countries, the conclusions do not change markedly. This result is consistent after accounting for oil price asymmetry, under positive and negative oil price shocks.

Background: Both duct tape and items retrieved from water are common pieces of evidence in forensic casework. However, there is little research uniting DNA recovery from immersed tape evidence. The...

This paper proposes a sticky inflation model in which inflation persistence is endogenously generated from the optimizing behavior of forward-looking firms. Although firms change prices periodically, their ability to fully adjust them in response to changes in economic conditions is assumed to be constrained due to the presence of managerial and customer costs of price adjustment. In essence, the model assumes that price stickiness arises from a combination of staggered contracts as in Calvo (1983) as well as quadratic adjustment cost as in Rotemberg (1982). We estimate the model using Bayesian techniques. Our findings strongly support both sources of price stickiness in the U.S. data. The model performs well in matching microeconomic evidence on price setting, particularly regarding the size and frequency of price changes. The paper also shows how incomplete price adjustments in a staggered price contracts model limit the contribution of expectations to inflation dynamics: it generates the delayed response of inflation to demand and monetary shocks, and the observed correlation between inflation and economic activity.

The algebraic stability theorem for persistence modules is a central result in the theory of stability for persistent homology. We introduce a new proof technique which we use to prove a stability theorem for n-dimensional rectangle decomposable persistence modules up to a constant $$2n-1$$ 2 n - 1 that generalizes the algebraic stability theorem, and give an example showing that the bound cannot be improved for $$n=2$$ n = 2 . We then apply the technique to prove stability for block decomposable modules, from which novel results for zigzag modules and Reeb graphs follow. These results are improvements on weaker bounds in previous work, and the bounds we obtain are optimal.

This paper investigates whether an electoral defeat has different effects on the subsequent political involvement of male and female candidates for state office. Using US state legislative election returns from 1972 to 2010 and a regression discontinuity design, I find that there is no gender difference in the effects of an electoral defeat on the propensity to run again for state legislature. I discuss possible explanations for why the gender gap in persistence documented among novice local politicians disappears among state politicians, focusing on the role of prior office-holding experience.

Why are the east sides of formerly industrial cities more deprived? To answer this question, we use individual-level census data and create historical pollution patterns derived from the locations of 5,000 industrial chimneys and an atmospheric model. We show that this observation results from path dependent neighborhood sorting that began during the Industrial Revolution as prevailing winds blew pollution eastwards. Past pollution explains up to 20% of the observed neighborhood segregation in 2011, even though coal pollution stopped in the 1970s. We develop a quantitative model to identify the role of neighborhood effects and relocation rigidities in underlying this persistence.

Rocks encountered in civil and mining engineering structures are generally intersected by discontinuities. The triaxial strength behaviour of a jointed rock intersected by a discontinuity has been a topic of keen interest for the engineering fraternity. It is well established that the strength behaviour of such rocks is highly non-linear. In the past, Barton’s critical state concept has been used to correctly define the curvature of the non-linear failure envelopes of intact and jointed rocks. The aim of the present study has been to evaluate the applicability of the critical state concept for the rock, which is intersected by non-persistent discontinuity having weak foreign material. Triaxial strength tests were conducted on specimens of rock like model material. The specimens were intersected by a non-persistent discontinuity with various combinations of orientation, degree of persistence and number of joint segments. The range of confining pressure was varied from zero (uniaxial loading condition) to reasonably high (critical state) values. The study indicates that the rock intersected by discontinuity comprising of joint segments (having weak foreign material) and intact rock bridges, do follow the critical state concept. However, the triaxial strength behaviour is substantially affected by the presence of non-persistent joints. It is shown that the critical state concept based Modified Mohr–Coulomb (MMC) criterion can be used with confidence to model the triaxial strength of rocks. Correlations have been suggested to assess the criterion parameters based on attributes of the discontinuity and intact rock.

We investigate the traveling wave solutions of a three-species system involving a single predator and a pair of strong-weak competing preys. Our results show how the predation may affect this dynamics. More precisely, we describe several situations where the environment is initially inhabited by the predator and by either one of the two preys. When the weak competing prey is an aboriginal species, we show that there exist traveling waves where the strong prey invades the environment and either replaces its weak counterpart, or more surprisingly the three species eventually co-exist. Furthermore, depending on the parameters, we can also construct traveling waves where the weaker prey actually invades the environment initially inhabited by its strong competitor and the predator. Finally, our results on the existence of traveling waves are sharp, in the sense that we find the minimal wave speed in all those situations., Comment: Journal of Differential Equations, Elsevier, 2021

In this paper, a stochastic SIRV epidemic model with general nonlinear incidence and vaccination is investigated. The value of our study lies in two aspects. Mathematically, with the help of Lyapunov function method and stochastic analysis theory, we obtain a stochastic threshold of the model that completely determines the extinction and persistence of the epidemic. Epidemiologically, we find that random fluctuations can suppress disease outbreak, which can provide us some useful control strategies to regulate disease dynamics. In other words, neglecting random perturbations overestimates the ability of the disease to spread. The numerical simulations are given to illustrate the main theoretical results.

Analyzing the shear resistance of a potential sliding surface based on discontinuity persistence usually does not consider the number of coplanar rock bridges. To examine the effect of the dispersion/number of rock bridges on the shear strength and rock slope stability, direct shear tests and large-scale rockslide simulations were conducted employing the 2D particle flow code (PFC2D). The shear strength of rock bridges under different configurations and the same discontinuity persistence was analyzed based on both the shear behavior controlled by the stress response and crack propagation. The results at both the laboratory and slope scales indicate that the shear resistance decreases with increasing dispersion/number of rock bridges due to multiple rock bridges breaking separately, the mechanism of which is that the rock bridge system more easily experiences initial failure with increasing dispersion/number of rock bridges. On this basis, a function of the strength reduction coefficient with the number of rock bridges was established considering the laboratory-scale numerical simulation results. A feasible stability analysis method, i.e., the improved limit equilibrium method based on the strength reduction coefficient, was proposed to consider the effect of the dispersion/number of rock bridges on the slope stability, which is a useful innovation to ensure that the stability analysis method of potential rockslides, including coplanar rock bridges, is more realistic and accurate.

An adaptive switching feedback control scheme is proposed for classes of discrete-time, positive difference equations, or systems of equations. In overview, the objective is to choose a control strategy which ensures persistence of the state, consequently avoiding zero which corresponds to absence or extinction. A robust feedback control solution is proposed as the effects of different management actions are assumed to be uncertain. Our motivating application is to the conservation of dynamic resources, such as populations, which are naturally positive quantities and where discrete and distinct courses of management actions, or control strategies, are available. The theory is illustrated with examples from population ecology.

Mechanisms regulating cell movement are not fully understood. One feature of cell movement that determines how far cells displace from an initial position is persistence, the ability to perform movements in a direction similar to the previous movement direction. Persistence is thus determined by turning angles between two sequential displacements and be characterized by an average turning angle or persistence time. Recent studies found that a cell’s average speed and turning are negatively correlated, suggesting a fundamental cell-intrinsic program whereby cells with a lower turning ability (i.e., larger persistence time) are intrinsically faster (or faster cells turn less). By simulating correlated or persistent random walks (PRWs) using two different frameworks (one based on von Mises-Fisher (vMF) distribution and another based on Ornstein-Uhlenbeck (OU) process) we show that the negative correlation between speed and turning naturally arises when cell trajectories are sub-sampled, i.e., when the frequency of sampling is lower than frequency at which cells make movements. This effect is strongest when the sampling frequency is on the order of magnitude with the typical cell persistence time and when cells vary in persistence time. Both conditions are observed for datasets of T cell movements in vivo that we have analyzed. In simulations the correlation arises due to randomness of cell movements resulting in highly variable persistence times for individual cells that with sub-sampling leads to large variability of average cell speeds. Interestingly, previously suggested methodology of calculating displacement of cell cohorts with different speeds resulted in similar results whether or not there is a cell-intrinsic correlation between cell speed and persistence. For both vMF- and OU-based simulations of PRWs we could find parameter values (distribution of persistence times, speeds, and sampling frequency) that matched experimentally measured correlations between speed and turning for two datasets of T cell movement in vivo suggesting that such simple correlations are not fully informative on the intrinsic link between speed and persistence. Our results thus suggest that sub-sampling may contribute to (and perhaps fully explains) the observed correlation between speed and turning at least for some cell trajectory data and emphasize the role of sampling frequency in inference of critical cellular parameters of cell motility such as speeds.Secondary AbstractMeasurement of cell movements often results in a negative correlation between average speed and average turning angle suggesting an existence of a universal, cell-intrinsic movement program. We show that such a negative correlation may arise if cells in the population differ in their ability for persistent movement when the movement data are sub-sampled. We show that sub-sampling of cell trajectories generated using two different frameworks of persistent random walk can match the experimentally observed correlation between speed and turning for T cell movements in vivo.

In this paper, we present new results on deterministic sudden changes and stochastic fluctuations’ effects on the dynamics of a two-predator one-prey model. We purpose to study the dynamics of the model with some impacting factors as the problem statement. The methodology depends on investigating the seasonality and stochastic terms which make the predator-prey interactions more realistic. A theoretical analysis is introduced for studying the effects of sudden deterministic changes, using three different cases of sudden changes. We show that the system in a good situation presents persistence dynamics only as a stable dynamical behavior. However, the system in a bad situation leads to three main outcomes as follows: first, constancy at the initial conditions of the prey and predators; second, extinction of the whole system; third, extinction of both predators, resulting in the growth of the prey population until it reaches a peak carrying capacity. We perform numerical simulations to study effects of stochastic fluctuations, which show that noise strength leads to an increase in the oscillations in the dynamical behavior and became more complex and finally leads to extinction when the strength of the noise is high. The random noises transfer the dynamical behavior from the equilibrium case to the oscillation case, which describes some unstable environments.

The autocorrelation function (ACF) and its finite Fourier transform, referred to as signal energy, have been investigated using the ECMWF daily surface temperature data. ACF itself provides a measure of the influence of leading fluctuation between two different time points. Considering the decay of ACF, it is found that the scaling power-rule of ACF is only valid in a very short period, as the decay of ACF exists before it reaches a random noise state. Therefore, the method of the critical exponent of ACF is limited in the short length of the temporal interval. On the other hand, the distributions of the signal energy always show nice patterns, indicating the degree of persistence change. It is found, for a short period, that the distributions of the signal energy and the critical exponent are very similar, with a correlation coefficient over 0.97. For a longer period, though the critical exponent of ACF becomes invalid, the signal energy can always provide an effective method to investigate climate persistence in different lengths of time. In a 5-day period of boreal winter, the southern part of North America has a larger value of signal energy compared to the northern part; thus, the surface temperature is more stable in the north part. The result becomes opposite in the boreal summer. The method of signal energy can also be applied to a particular interval of time. In different temporal intervals, the signal energy presents very different results, especially over the El Nino regions

In this paper, we consider an asymptotic model for wave propagation in shallow water with the effect of the Coriolis force is derived from the governing equation in two dimensional flows. Motivated by the eariler works (Brandolese in Int Math Res Not 22:5161–5181, 2012; Escauriaza et al. in J Funct Anal 244:504–535, 2007; Himonas et al. in Commun Math Phys 271:511–522, 2007; Himonas and Misiolek in Math Ann 327:575–584, 2003; Kohlmann in Z Angew Math Mech 94:264–272, 2014), we demonstrate the persistence results for the solution in weighted $$L^p$$ spaces for a large classs of moderate weights. We also discuss the spatial asymptotic profiles of solutions to this model equation. Finally, with analytic initial data, we show that its solutions are analytic in both variables, globally in space and locally in time.

Despite the ending of apartheid, regional wage disparities remain prevalent in South Africa with the former homelands characterised by persistently low wages and incomes. In this paper, we use a new economic geography (NEG) model to estimate the extent to which the persistence in apartheid regional wage disparities are an outcome of economic forces such as access to markets. We estimate a structural wage equation derived directly from the NEG theory for 354 regions over the period 1996 to 2011. We find support for the NEG model in explaining regional wage disparities across regions in South Africa, although the market access effects are highly localised in view of high distance coefficients. We also find a wage deficit in homeland areas even after controlling for NEG and other region-specific characteristics. Average wages of workers in homeland areas were 11.8% lower than predicted in 1996, with this gap rising to 13.3% in 2011. This gap remains using alternative estimation approaches and the inclusion of controls for infrastructure, removal of incentives under the deconcentration policies and local amenities.

We consider a two-species Lotka--Volterra competition-diffusion model with a shifting habitat. The growth rate of each species is nondecreasing along the $x$-axis, and it changes sign and shifts ri...

It is well known that movement strategies in ecology and in economics can make the difference between extinction and persistence. We present a unifying model for the dynamics of ecological populati...