2,301 research outputs found

    Study of Mathematical Modeling for Plant Disease Transmission: A Systematic Literature Review during 2012-2022

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    Many models representing disease transmission have been constructed and analyzed mathematically. However, literature studies on the mathematical models for vector-borne disease are sparse, especially on the plant disease transmission model. This study aims to obtain information about the research conducted and find room for developing the model, including mathematical analysis, intervention used, and biological factors considered. We employ a Systematic Literature Review (SLR) to explore all of the studies on plant disease transmission modeling collected from four digital databases. First, the JabRef reference manager helps conduct the inclusion and exclusion processing. Then, we obtain 60 selected articles that passed the criterion. Next, the VOSviewer application is resulting a bibliometric analysis of the database containing chosen articles. Finally, we classify the model constructed based on the system used and elaborate on the intervention used. The results show that the existing researcher clusters are not linked to each other, and the models only consider usual interventions such as roguing and insecticide spraying. Hence, there is much room to build collaboration between the researcher and develop models for plant disease transmission by considering the other various intervention and biological factors in the model to improve further

    A soil water indicator for a dynamic model of crop and soil water interaction

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    Water scarcity is a critical issue in agriculture, and the development of reliable methods for determining soil water content is crucial for effective water management. This study proposes a novel, theoretical, non-physiological indicator of soil water content obtained by applying the next-generation matrix method, which reflects the water-soil-crop dynamics and identifies the minimum viable value of soil water content for crop growth. The development of this indicator is based on a two-dimensional, nonlinear dynamic that considers two different irrigation scenarios: the first scenario involves constant irrigation, and the second scenario irrigates in regular periods by assuming each irrigation as an impulse in the system. The analysis considers the study of the local stability of the system by incorporating parameters involved in the water-soil-crop dynamics. We established a criterion for identifying the minimum viable value of soil water content for crop growth over time. Finally, the model was calibrated and validated using data from an independent field study on apple orchards and a tomato crop obtained from a previous field study. Our results suggest the advantages of using this theoretical approach in modeling the plants' conditions under water scarcity as the first step before an empirical model. The proposed indicator has some limitations, suggesting the need for future studies that consider other factors that affect soil water content

    Effects of additional food availability and pulse control on the dynamics of a Holling-(p+1) type pest-natural enemy model

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    In this paper, a novel pest-natural enemy model with additional food source and Holling-(p p +1) type functional response is put forward for plant pest management by considering multiple food sources for predators. The dynamical properties of the model are investigated, including existence and local asymptotic stability of equilibria, as well as the existence of limit cycles. The inhibition of natural enemy on pest dispersal and the impact of additional food sources on system dynamics are elucidated. In view of the fact that the inhibitory effect of the natural enemy on pest dispersal is slow and in general deviated from the expected target, an integrated pest management model is established by regularly releasing natural enemies and spraying insecticide to improve the control effect. The influence of the control period on the global stability and system persistence of the pest extinction periodic solution is discussed. It is shown that there exists a time threshold, and as long as the control period does not exceed that threshold, pests can be completely eliminated. When the control period exceeds that threshold, the system can bifurcate the supercritical coexistence periodic solution from the pest extinction one. To illustrate the main results and verify the effectiveness of the control method, numerical simulations are implemented in MATLAB programs. This study not only enriched the related content of population dynamics, but also provided certain reference for the management of plant pest

    Three Essays on Individuals’ Vulnerability to Security Attacks in Online Social Networks: Factors and Behaviors

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    With increasing reliance on the Internet, the use of online social networks (OSNs) for communication has grown rapidly. OSN platforms are used to share information and communicate with friends and family. However, these platforms can pose serious security threats to users. In spite of the extent of such security threats and resulting damages, little is known about factors associated with individuals’ vulnerability to online security attacks. We address this gap in the following three essays. Essay 1 draws on a synthesis of the epidemic theory in infectious disease epidemiology with the social capital theory to conceptualize factors that contribute to an individual’s role in security threat propagation in OSN. To test the model, we collected data and created a network of hacked individuals over three months from Twitter. The final hacked network consists of over 8000 individual users. Using this data set, we derived individual’s factors measuring threat propagation efficacy and threat vulnerability. The dependent variables were defined based on the concept of epidemic theory in disease propagation. The independent variables are measured based on the social capital theory. We use the regression method for data analysis. The results of this study uncover factors that have significant impact on threat propagation efficacy and threat vulnerability. We discuss the novel theoretical and managerial contributions of this work. Essay 2 explores the role of individuals’ interests in their threat vulnerability in OSNs. In OSNs, individuals follow social pages and post contents that can easily reveal their topics of interest. Prior studies show high exposure of individuals to topics of interest can decrease individuals’ ability to evaluate the risks associated with their interests. This gives attackers a chance to target people based on what they are interested in. However, interest-based vulnerability is not just a risk factor for individuals themselves. Research has reported that similar interests lead to friendship and individuals share similar interests with their friends. This similarity can increase trust among friends and makes individuals more vulnerable to security threat coming from their friends’ behaviors. Despite the potential importance of interest in the propagation of online security attacks online, the literature on this topic is scarce. To address this gap, we capture individuals’ interests in OSN and identify the association between individuals’ interests and their vulnerability to online security threats. The theoretical foundation of this work is a synthesis of dual-system theory and the theory of homophily. Communities of interest in OSN were detected using a known algorithm. We test our model using the data set and social network of hacked individuals from Essay 1. We used this network to collect additional data about individuals’ interests in OSN. The results determine communities of interests which were associated with individuals’ online threat vulnerability. Moreover, our findings reveal that similarities of interest among individuals and their friends play a role in individuals’ threat vulnerability in OSN. We discuss the novel theoretical and empirical contributions of this work. Essay 3 examines the role addiction to OSNs plays in individuals’ security perceptions and behaviors. Despite the prevalence of problematic use of OSNs and the possibility of addiction to these platforms, little is known about the functionalities of brain systems of users who suffer from OSN addiction and their online security perception and behaviors. In addressing these gaps, we have developed the Online addiction & security behaviors (OASB) theory by synthesizing dual-system theory and extended protection motivation theory (PMT). We collected data through an online survey. The results indicate that OSN addiction is rooted in the individual’s brain systems. For the OSN addicted, there is a strong cognitive-emotional preoccupation with using OSN. Our findings also reveal the positive and significant impact of OSN addiction on perceived susceptibility to and severity of online security threats. Moreover, our results show the negative association between OSN addiction and perceived self-efficacy. We discuss the theoretical and practical implications of this work

    Models of collaboration between psychologist and family doctor: a systematic review of primary care psychology

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    open2noThe prevalence of psychological suffering is greater than the actual request for clinical consultation in Europe (Alonso et al., 2004). In Italy, no more than 5.5% of the population requested psychological assistance during lifetime (Miglioretti et al., 2008). There are different obstacles that prevent the access to mental health services, such as economic restrictions (Mulder et al., 2011), cultural prejudice (Kim et al., 2010), and lack of knowledge about the service providers that can answer to the patient’s psychological needs (Molinari et al., 2012). Therefore, the psychologist is often consulted as a last resort, only after everything else has failed, when problems have become severe, and thus requiring longer, more intensive, and expensive treatments. The introduction of the Primary Care Psychologist, a professional who works together with the family doctor, allows to overcome the above-mentioned problems and intercept unexpressed needs for psychological assistance. This professional role is operating in many countries since several years. In this study, current literature concerning different models of collaboration between physician and psychologist, in Europe and in Italy, was reviewed. A systematic search of Web of Science (ISI), Pubmed, Scopus, and PsychINFO was conducted using the initial search terms Primary Care Psychologist, Family Doctor, Primary Care, Collaborative Practice, and several relevant papers were identified. The review has shown the improved quality of care when mental health care is integrated into primary. Analyzing how different programs are implemented, results indicated that the more efficacious models of Primary Care Psychology are those tailored on the environment’s needs.The results of our systematic review stress the importance of the Primary Care Psychologist implementation also in Italy, to intercept unexpressed psychological needs and enhance clients’ quality of life.openFrancesca, Bianco; Enrico, BenelliBianco, Francesca; Benelli, Enric

    Nonlinear Systems

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    Open Mathematics is a challenging notion for theoretical modeling, technical analysis, and numerical simulation in physics and mathematics, as well as in many other fields, as highly correlated nonlinear phenomena, evolving over a large range of time scales and length scales, control the underlying systems and processes in their spatiotemporal evolution. Indeed, available data, be they physical, biological, or financial, and technologically complex systems and stochastic systems, such as mechanical or electronic devices, can be managed from the same conceptual approach, both analytically and through computer simulation, using effective nonlinear dynamics methods. The aim of this Special Issue is to highlight papers that show the dynamics, control, optimization and applications of nonlinear systems. This has recently become an increasingly popular subject, with impressive growth concerning applications in engineering, economics, biology, and medicine, and can be considered a veritable contribution to the literature. Original papers relating to the objective presented above are especially welcome subjects. Potential topics include, but are not limited to: Stability analysis of discrete and continuous dynamical systems; Nonlinear dynamics in biological complex systems; Stability and stabilization of stochastic systems; Mathematical models in statistics and probability; Synchronization of oscillators and chaotic systems; Optimization methods of complex systems; Reliability modeling and system optimization; Computation and control over networked systems

    Classical Engineering Systems Provide Behavioral Analog for Ephemeral Insect and Plant Biomechanics

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    In this dissertation we consider ephemeral behaviors of two small-scale living systems, mosquitoes and citrus fruit reservoirs. While these two systems share few obvious commonalities, they both express life events that are complex and conclude within approximately 50 milliseconds. We utilize high-speed videography, between 1,000-16,000 fps, to detail how complex behavior can be modeled as classical engineering systems. Beginning with the larger organism we assessed the landing and takeoff behavior of Aedes aegypti mosquitoes to ascertain the secrets of their covert interaction with humans. At takeoff, mosquitoes decrease pushing contact time with substrates of low friction through a modified takeoff behavior of striking the substrate with a hind-leg prior to a classic push phase. We propose a 2D analog where the striking leg acts as a rotating cantilever about a fixed end that generates upward momentum with a small penalty in body rotation. Landing mosquitoes are filmed in 2D and modeled as a mass-spring-damper system whose natural frequency, damping coefficient, ratio, and spring constant are determined experimentally and validated through a nonlinear least square solver fitting of the free vibration ODE\u27s general solution. Results indicate mosquitoes behave as an underdamped system to scrub their incoming momentum through extending impact duration, effectively reducing temporal impact force. Shrinking in scale we proceed to characterize citrus reservoir rupture as a passive system capable of microjetting oil through expanding orifices at accelerations greater than 5000 gravities. Citrus reservoirs are modeled as ellipsoidal pressure vessels capped by a thin membrane of contrasting stiffness to the surrounding ductile compressible albedo

    The role of prefrontal cortex and serotonin in foraging decisions

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    "Deciding whether to give up on a course of action or persist in the hope that our efforts will pay off is a crucial but hard problem to define and optimize. What information is best to take into account? What returns justify the costs? What are the costs and benefits of taking an alternative course of action? Considering all these questions simultaneously seems hard, yet, animals routinely solve this conundrum while foraging. Using behavioral, computational and neuronal activity manipulation techniques, in this thesis, we investigate how the brain solves this problem. Specifically, we aim to deepen our understanding of two aspects: how the agent represents the environment in order to extract information suitable to guide its foraging decisions, and how serotonin activity can bidirectionally modulate this decision process.(...)
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