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In the domain of computer technology, image processing strategies have become a part of various applications. A few broadly used image segmentation methods have been characterized as seeded region growing (SRG), edge-based image segmentation, fuzzy $k$-means image segmentation, etc. SRG is a quick, strongly formed and impressive image segmentation algorithm. In this paper, we delve into different applications of SRG and their analysis. SRG delivers better results in analysis of magnetic resonance images, brain image, breast images, etc. On the other hand, it has some limitations as well. For example, the seed points have to be selected manually and this manual selection of seed points at the time of segmentation brings about wrong selection of regions. So, a review of some automatic seed selection methods with their advantages, disadvantages and applications in different fields has been presented.

Optical problems, related to the particle on the surface, i.e. optical resonance and near-field effects in laser cleaning are discussed. It is shown that the small transparent particle with size by the order of the wavelength may work as a lens in the near-field region. This permits to focus laser radiation into the area with the sizes, smaller than the radiation wavelength. It leads to 3D effects in surface heating and thermal deformation, which influences the mechanisms of the particle removal.

A model for nanosecond dry laser cleaning that treats the substrate and particle expansion on a unified basis is proposed. Formulas for the time-dependent thermal expansion of the substrate, valid for temperature-dependent parameters, are derived. Van der Waals adhesion, substrate and particle elasticity, and particle inertia are taken into account for an arbitrary temporal profile of the laser pulse. The characteristic time for the particle on the surface system is deduced. This time is related to the size of the particles as well as the adhesion and elastic constants. Cleaning proceeds in different regimes if die duration of the laser pulse is much shorter or longer than this time. Expressions for cleaning thresholds are provided and compared with experiments on the 248 nm KrF excimer-laser cleaning of Si surfaces from spherical SiO₂ particles with radii between 235 and 2585 nm in vacuum. Discrepancies between the experimental data and theoretical results seem to indicate that nanosecond dry laser cleaning cannot be explained purely on the basis of one-dimensional tiiermal expansion mechanism.

This study investigates the correlation between weather and agricultural futures markets on the basis of detrended cross-correlation analysis (DCCA) cross-correlation coefficients and $q$-dependent cross-correlation coefficients. In addition, detrended fluctuation analysis (DFA) is used to measure extreme weather and thus analyze further the effect of this condition on agricultural futures markets. Cross-correlation exists between weather and agricultural futures markets on certain time scales. There are some correlations between temperature and soybean return associated with medium amplitudes. Under extreme weather conditions, weather exerts different influences on different agricultural products; for instance, soybean return is greatly influenced by temperature, and weather variables exhibit no effect on corn return. Based on the detrending moving-average cross-correlation analysis (DMCA) coefficient and DFA regression results are similar to that of DCCA coefficient.

This paper formulates and studies a delayed chemostat with Lévy noises. Existence of the globally positive solution is proved first by establishing suitable Lyapunov functions, and a further result on exact Lyapunov exponent shows the growth of the total concentration in the chemostat. Then, we prove existence of the uniquely ergodic stationary distribution for a subsystem of the nutrient, based on this, a unique threshold is identified, which completely determines persistence or not of the microorganism in the chemostat. Besides, recurrence is studied under special conditions in case that the microorganism persists. Results indicate that all the noises have negative effects on persistence of the microorganism, and the time delay has almost no effects on the sample Lyapunov exponent and the threshold value of the chemostat.

In real life, multiple attribute decision problems (MADM) can be applied in different areas and numerous related extensions and methodologies have been proposed by researchers. Combining three-way TOPSIS decision ideas with MADM is a feasible and meaningful research direction. In light of this, this paper generalizes the classical TOPSIS method with the help of mean and standard deviation and proposes the so-called modified three-way TOPSIS. First, using a pair of thresholds which is derived by mean and standard deviation, we divide decision alternatives into three segments, and then a preliminary rank results of decision alternatives can be obtained. Furthermore, in each decision region, we use two ranking regulations (one-way TOPSIS or modified two-way TOPSIS method) to rank decision alternatives. A practical example of urban expressway route selection illustrates the feasibility of the proposed method. Finally, we test the feasibility and validity of the modified three-way TOPSIS method by comparing with some existing method.

We propose a (t, n)-threshold multiparty quantum-information splitting protocol following some ideas of the standard teleportation protocol [C. H. Bennett, G. Brassard, C. Crpeau, R. Jozsa, A. Peres and W. K. Wootters, Phys. Rev. Lett.70 (1993) 1895] and Tokunaga et al.'s protocol [Y. Tokunaga, T. Okamoto and N. Imoto, Phys. Rev. A71 (2005) 012314]. The sender distributes the classical shared keys to his or her n agents and each agent owns a secret key in advance. The sender's quantum information can be extracted by an agent subset by collaboration in such a way that at least t or more agents can get the quantum information with the mutual assistances but any t - 1 or fewer agents cannot. In contrast to the previous multiparty quantum-information splitting protocols in which the sender's quantum information can be recovered only if all the agents collaborate, our protocol is more practical and more flexible.

One common method for assessing the affordability of water supply, sanitation, and hygiene (WASH) services is to compare a household’s reported WASH expenditure, as a proportion of total household expenditure, to a predefined threshold. Another common method is to subtract this reported WASH expenditure from the household’s total income (or expenditure), and then compare that result against a minimum amount needed to purchase other basic goods and services. The innovative, alternative approach to determining affordability introduced in this paper borrows from the method commonly used to draw the monetary poverty line. This offers five advantages over the common methods of investigating the affordability of WASH services. First, it defines a “basket” of WASH services that accounts for the type and level of WASH services that a household receives (and that involves a threshold quality of service, deemed necessary for health and well-being). Second, it makes use of the actual costs of service, therefore moving away from household estimates of WASH expenditure that tend to be inadequate and rarely reflect actual costs. Third, it considers both initial fixed costs and recurring consumption costs, each of which pose their own unique challenges to affordability. Fourth, it makes use of household-level data on access to WASH services, which allows for the grouping of households into categories with distinct policy implications. Finally, this approach facilitates scenario analyses, whereby the impact of different pricing policies can be assessed. This approach is then applied to rural Nigeria, using data from the General Household Survey (GHS) 2015–16, to demonstrate its utility as a tool to better focus policy reform on the actual affordability constraints of the unserved.

The negative or hyperpolarization pulse stimulation induces action potential, i.e. the post-inhibitory rebound spike, which has been widely observed in various single neurons with hyperpolarization-activated cation current ($I_{\mathrm{\text{h}}}$) in neuroscience and is suggested to be evoked from a focus near the Hopf bifurcation according to the traditional viewpoint of nonlinear dynamics. In the present paper, a novel viewpoint that post-inhibitory rebound spike can be evoked from a stable node near the saddle-node bifurcation on invariant circle (SNIC) is proposed, which can be well interpreted with hyperpolarization activation characteristic of $I_{\mathrm{\text{h}}}$ current, bifurcation analysis, and threshold. Especially, the boundary between the subthreshold and suprathreshold initial values which respectively evoke subthreshold potential and action potential is acquired to be a threshold surface containing the saddle. $I_{\mathrm{\text{h}}}$ current after the negative pulse stimulation for small conductance $g_{\mathrm{\text{h}}}$ of $I_{\mathrm{\text{h}}}$ is low enough to evoke just a subthreshold potential while for large $g_{\mathrm{\text{h}}}$ is high enough to evoke a post-inhibitory rebound spike. For small $g_{\mathrm{\text{h}}}$, the pulse induces the decrease of membrane potential $V$ and then the phase trajectory always stays within the subthreshold initial value region locating lower to the threshold surface with a nearly fixed $V$ value. For large $g_{\mathrm{\text{h}}}$, the threshold surface changes and is composed of two parts: one part with a nearly fixed $V$ value and the other with a nearly fixed value of $H$ variable to describe $I_{\mathrm{\text{h}}}$ inactivation probability. Although the negative pulse stimulation induces the decrease of $V$, $H$ increases to a level high enough and then the phase trajectory runs across the part with a nearly fixed $H$ value to form a post-inhibitory rebound spike. The appearance of the novel $H$ threshold is the internal dynamical mechanism for the generation of post-inhibitory rebound spike, and the external cause is that the negative pulse stimulation induces the phase trajectory to run across the $H$ threshold surface. The results present a novel nonlinear phenomenon and the corresponding dynamical mechanism related to post-inhibitory rebound spike induced by $I_{\mathrm{\text{h}}}$ current near the SNIC bifurcation point.

In the interaction between plants and herbivores that live in the same ecosystem, understanding the conditions in which co-existence equilibrium occurs answers a major question in Ecology. In this interaction, plants serve as food for herbivores on the food chain. Then the livelihood of herbivores highly depends on the availability of food, in this case the availability of plants. Moreover, the abundance of the plant density alone does not guarantee the non-extinction of the herbivore population as they are assumed to reproduce sexually. With this motivation, in this paper a predator–prey mathematical model is reformulated such that the death rate of the herbivore population is dependent on the plant density and their emergence is also governed by the Allee effect. Using the mathematical theory of dynamical system, threshold conditions are obtained for the non-extinction of the herbivore population and a trapping region is obtained to ensure co-existence of the population. Moreover, it has been shown that the dynamics of the population is significantly sensitive to the feeding rate and the harvest rate of the herbivore population.

This paper deals with stochastic Chikungunya (CHIKV) virus model along with saturated incidence rate. We show that there exists a unique global positive solution and also we obtain the conditions for the disease to be extinct. We also discuss about the existence of a unique ergodic stationary distribution of the model, through a suitable Lyapunov function. The stationary distribution validates the occurrence of disease; through that, we find the threshold value for prevail and disappear of disease within host. With the help of numerical simulations, we validate the stochastic reproduction number $R_0^S$ as stated in our theoretical findings.

This paper evaluates the impact of demographic change on the economic growth of OECD and non-OECD countries. An annual panel dataset of 71 countries, consisting of 27 advanced economies and 44 emerging economies over the period of 1981–2014, is used. Two types of regression models (panel regression model and panel continuous threshold model) including several demographic variables are used to investigate the effects of demographic structure. The results of this study show the significant difference of the impact of demographic transition on the economic growth of OECD and non-OECD economies.

Blast-induced traumatic brain injury (bTBI) has become a signature injury in recent military conflicts and terrorist attacks. However, the mechanisms and thresholds for such injury are still unknown. In this paper, effort has been made toward establishing the threshold due to primary blast based on the published injury data in the rat. Peak incident overpressure and pulse duration of the incident wave were used as predictors and the injury risk curves for the rat were derived via a linear logistic regression analysis. A scaling law based on body mass was then used to scale the tolerance curves from the rat to the pig and the human. The injury risk curve for bTBI was compared with that for the lung. The results reveal different injury mechanisms between these two organs. The developed injury curves can be used in the design of personal protective equipment against primary bTBI.

This paper is concerned with a stochastic single-species system with Lévy jumps in a polluted environment. Some sufficient conditions on extinction, non-persistence in the mean, weak persistence in the mean, strong persistence in the mean, stability in the mean and stochastic permanence are obtained. The threshold between extinction and weak persistence in the mean is established. At the same time, under a simple condition, it is proved that this threshold also is the threshold between extinction and stability in the mean. The results reveal that Lévy jumps have significant effects to the persistence and extinction results.

We study an SEIRS epidemic model with an isolation and nonlinear incidence rate function. We have obtained a threshold value $R_0$ and shown that there is only a disease-free equilibrium point, when $R_0<1$ and an endemic equilibrium point if $R_0>1$. We have shown that both disease-free and endemic equilibrium point are globally stable.

Acquired immunodeficiency syndrome (AIDS) has a serious impact on human health and life safety. In order to study its related factors, this paper establishes an HIV/AIDS model with treatment individuals based on heterosexual contact and male-to-male sexual contact. Using the method of next generation matrix, the threshold $R_0$ of the model is given. When $R_0<1$, it proves the global stability of the disease-free equilibrium. When $R_0>1$, it studies the dynamics of the boundary equilibrium and the endemic equilibrium under different conditions. Finally, through numerical simulations, the correctness of the theoretical results is verified. The key parameters affecting the spread of HIV are found through parameter sensitivity analysis, which provides a theoretical basis for effective control of the spread of HIV.

We consider a multi-server queueing model in which arrivals occur according to a Markovian arrival process (MAP). There is a single-server and additional (backup) servers are added or removed depending on sets of thresholds. The service times are assumed to be exponential and the servers are assumed to be homogeneous. A comparison of this model to the classical MAP/M/c queueing model through an optimization problem yields some interesting results that are useful in practical applications. For example, we notice that positively correlated arrival process appears to benefit with the threshold type queueing model. We also give the minimum delay costs and the associated maximum setup costs so that the threshold type queueing model is to be preferred over the classical MAP/M/c model.

In this paper, the neuronal firing patterns under extracellular sinusoidal electric field (EF) are investigated based on a reduced two-compartment model with focus on the effects of morphological and internal coupling parameters. We observe that the neuron can exhibit bursting, synchronous firing and subthreshold oscillation depending on EF amplitude A and frequency f. Furthermore, neuronal firing properties change obviously over a range of morphological parameter p. As p increases, the firing region expands first and then diminishes gradually until it disappears in the observed (A, f) parameter space and the transition from bursting to synchronous firing is also markedly distinct. Meanwhile, the morphological parameter also has significant effects on the EF threshold for triggering neuronal spikes. Unlike morphological parameter, though the internal coupling conductance g_c can also induce some changes in firing behavior and EF threshold, it cannot qualitatively change neuronal dynamical properties. All these results demonstrate that neuronal morphology plays a crucial role in neuronal responses to sinusoidal EF.

In this article, we consider a SIV infectious disease control system with two-threshold guidance, in which infection rate and vaccination rate are represented by a piecewise threshold function. We analyze the global dynamics of the discontinuous system using the theory of differential equations with discontinuous right-hand sides. We find some dynamical behaviors, including the disease-free equilibrium and endemic equilibria of three subsystems, a globally asymptotically stable pseudo-equilibrium and two endemic equilibria bistable, one of the two pseudo-equilibria or pseudo-attractor is stable. Conclusions can be used to guide the selection of the most appropriate threshold and parameters to achieve the best control effect under different conditions. We hope to minimize the scale of the infection so that the system can eventually stabilize at the disease-free equilibrium, pseudo-equilibrium or pseudo-attractor, corresponding to the disease disappearing or becoming endemic to a minimum extent, respectively.

We study a discrete-time model of host–parasitoid interactions, where the host is subject to a strong Allee effect and the parasitoid is aggregated. The system may have multiple coexisting steady states and there are two host population thresholds. The hosts become extinct if it is below the Allee threshold. The other threshold depends on the Allee threshold beyond which the host also becomes extinct due to overcompensated density dependence. When the initial host population size is between the two thresholds, we derive a critical parasitoid population size above which both populations become extinct. The critical size depends on the degree of aggregation of parasitoids. It is shown that both populations are more likely to become extinct if parasitoid aggregation is increased. Numerical simulations reveal that a strong Allee effect on the host can stabilize the host–parasitoid interactions on one hand but may drive both populations to extinction on the other hand. Further, aggregation of the parasitoid can promote population persistence when the host is subject to a strong Allee effect with a large Allee threshold. However, a more aggregated parasitoid population is more vulnerable to extinction if the growth rate of hosts is large.