Journal of Occupational and Organizational Psychology

Neri Guzmán J.C., González Ramírez P.I., Becerra Bizarrón M.E., Domínguez Valdez B.M.

This chapter presents the results of an investigation on entrepreneurial intention in 2014 university students in Mexico. In this chapter, the theory of planned behavior (Ajzen, The theory of planned behavior, organizational behavior and human decision processes, 50(2):179–211, ISSN 0749-5978, https://doi.org/10.1016/0749-5978(91)90020-T , 1991) was used, analyzed under a structural equation model that allows us to evaluate how the variables attitude toward entrepreneurship, subjective norms, perceived behavioral control and entrepreneurial spaces allow us to explain the intention of entrepreneur in university students. The study showed that there is a statistically significant and a strong and positive relationship between entrepreneurship spaces and the entrepreneurial intention of young people studying a career in administration and business at public universities.

Ahammed S.M., Roy P.K., Wang S.

As fossil fuels decline on a global scale, there is a rising interest in developing a cost-effective process for producing biodiesel from renewable sources, like Jatropha curcas plant. Enzymatic transesterification of Jatropha oil with alcohol is an effective technique to produce biodiesel. Due to mass transfer limitation between Jatropha oil and alcohol, the reaction is very slow. To overcome this we have used ultrasound frequency for excessive production of biodiesel. This article examines the impact of ultrasound frequency on the enzymatic transesterification of Jatropha oil through a mathematical model. Optimal control theory through Pontryagin Minimum Principle is employed on ultrasound to optimize frequency and improve cost-effectiveness of the system. The model’s validity is confirmed through simulated results and comparison with experimental data from the literature.

Baidya P., Panja S.K., Mandal S.C.

This study investigated the effects of an impact load on a pair of colinear rigid strips in an infinite isotropic medium. This investigation is prompted by the presence of a mixed boundary value problem arising from the interaction of waves. Utilizing Fourier and Laplace transformations, along with integral transformation techniques, the mixed boundary value problem is converted into a dual integral equation. Subsequently, the perturbation technique is employed to solve these integral equations, and the Hilbert transformation is utilized for effective simplification and solution. The computed Stress Intensity Factor is then graphically depicted over time, illustrating its behavior in isotropic materials.

Kushary S., Roy P.K., Cao X.

In this research, we have formulated a mathematical model by employing a set of nonlinear ordinary differential equations (ODEs) to explain the dynamics of the disease psoriasis. As primary populations, we have considered the densities of two major sub-types of T-cells ( $$Th_1$$ and $$Th_{17}$$ cells) and keratinocytes. To ensure the importance of this cell replacement strategy, we have considered mesenchymal stem cells (MSCs) as a secondary population. Then we have observed from a mathematical point of view how the primary immune cells interact with MSC and how the cytokine storm will slow down with the effect of umbilical cord-derived MSC (UC-MSC) transplantation in a pulsed manner. Our theoretical investigation and the numerical findings may provide a new insight into psoriasis therapy approaches and may be proposed as a treatment policy for future clinical trials.

Ghosh A.K., Roy L., Saxena S.

Since the origin of life, the most primitive organisms attempted to adapt in different climatic condition and became successful in their survival in adverse as well as congenial environment. In this backdrop, the present analysis on selected fossil marine phytoplankton and zooplankton has been taken into consideration from the sediments of northeast Indian Ocean ranging in age from ~16.4 million years old (Miocene Epoch) to ~4.19 million years old (Pliocene Epoch). Morphometric analysis of selected seven species of significant phytoplankton—calcareous nannofossils has been performed. Twenty randomly-selected specimens of each species were studied in each sample. The data was imported into the software PAST, where box-plot diagrams were created in order to observe possible variations in the size of the specimens. Several climatic events during Miocene to Pliocene have been earmarked. It has been visualized that at least seven different species of calcareous nannofossils continued their existence during this period. However, variations in size have been observed in those species and their gradual change in size have been studied. The shells of marine zooplankton radiolarians are composed of opaline silica and their shell volume plays an important role for their adaptation and diversity. The shell volumes of five suitable nassellarian and one spumellarian radiolarian species recovered from the sediments of deep-sea drill cores have been measured from two dimensional microscopic studies using a mathematical formula. The volume of silica used by individual radiolarian species was estimated by considering as hollow spheres or cones. Both these studies from the northeast Indian Ocean is a new approach as it was not attempted earlier from this region. These changes observed both in phytoplankton size and zooplankton volume can be attributed to different climatic events as well as their evolution in time and space.

Ghosh T., Schwartz E.J., Ghosh S., Roy P.K.

Successful replication of Human Immunodeficiency Virus requires viral genome reverse transcription to generate proviral DNA and integration into the target cell genome. In this research article, we explore the relative effect of physical interactions between two enzymes RT and IN on two of the most fundamental sequential processes in HIV replication, namely, reverse transcription and integration. Activities of these two pivotal enzymes are targets of antiretroviral drugs. We also investigate the crucial impact of these antiretroviral drugs on the control-induced mathematical model by incorporating two bounded control parameters into our system. More specifically, we apply the well-known Pontryagin minimum principle to minimize the concentrations of viral DNA and the pre-integration complex (PIC), utilizing two control functions: $$m_1(t)$$ as a reverse transcriptase inhibitor and $$m_2(t)$$ as an integrase inhibitor. We found that the affinity of RT and IN enzymes towards each other and the impacts of their direct interaction on the biochemical processes play pivotal roles in HIV replication dynamics, which further guide the development of a realistic optimal control-induced policy. All of our achieved analytical outcomes have been confirmed through numerical simulations.

Nath S.C., Karmaker R., Deb U.K.

Springs are stretchy objects that can store mechanical energy by changing their shape when a force is applied and returning to their original shape when the force is removed. Springs are very useful in many applications, such as active suspension systems for vehicles, which can make the ride smoother and safer. This study aims to model and evaluate the best material for such a system. The investigation utilizes COMSOL Multiphysics software to model the deformation and stretching of steel and iron suspension springs found in spiral two-wheelers. The study also explores the nonlinear dynamic behavior of spiral springs with higher mass, assuming constant pitch and elasticity. The simulation results are compared for both steel and iron springs with those obtained by the finite element method. The study found that steel springs have better suspension performance than iron springs, as they can bend more without breaking and spread the force evenly along the coil. Steel springs also have higher corrosion resistance than iron springs, which means they can last longer and look better. Therefore, steel springs are more suitable for helical suspension systems in terms of weight reduction, energy efficiency, and cost-effectiveness and steel springs are a smart choice for improving the operation and lifetime of vehicles.

Debnath S.

The object of the present paper is to study conformal $$\eta $$ -Einstein soliton in the framework of $$(LCS)_{n}$$ -manifold. First we establish the existence of conformal $$\eta $$ -Einstein soliton on $$(LCS)_{n}$$ -manifold. Then we obtain some results on $$(LCS)_{n}$$ -manifold admitting conformal $$\eta $$ -Einstein soliton where the Ricci tensor is cyclic parallel and Codazzi type. We have also considered the soliton where the manifold is Ricci symmetric.

Lallawmzuali M., Muniyan S.

Uttarakhand is currently experiencing heavy rains, and it drew our attention to carry out a statistical analysis over the 50 years of rainfall data to predict the rainfall pattern of the region for contributing a speck towards the interest of the country, which may be useful for stakeholders, policymakers, economists, agriculturists, environmentalists, and the Department of Natural Disaster Management. This study presents a comprehensive analysis of the probability distribution of rainfall in Uttarakhand, from 1971 to 2020, using the most appropriate distributive functions out of 18 different probability distributions, which would be selected from the statistical approach. The main objective of this study is to identify the most suitable probability distribution for monthly rainfall in Uttarakhand. Our results indicated that the Generalized Extreme Value distribution was the best fit for 3 out of 12 months (Feb, Jul, Aug), followed by the Normal distribution, which was the best fit for 2 out of 12 months (Apr, Sep) and the Weibull (2P) distribution was the best fit for 2 out of 12 months (May, Nov). Further, month-wise rainfall has been predicted from 2030 to 2070 years for each decade to study the change in rainfall patterns using past rainfall records.

Sardar S., Roy P.K., Kushary S., Greenhalgh D.

Methanol poisoning is a relatively uncommon yet highly perilous form of intoxication, leading to central nervous system depression, vision impairment, metabolic disruption, and even more deadly consequences if not quickly and effectively addressed. Keeping this in mind, this work primarily studies activated charcoal as first aid for methanol-intoxicated persons. In this research article, we initially develop a mathematical model for methanol-enzyme interaction, along with the effects of folate therapy. We consider a unique form of the Dubinin-Astakhov (DA) equation that characterizes the adsorption of methanol on activated charcoal. The impulsive differential equation which we formulate, based on the DA equation, examines the efficacy of activated charcoal in treating methanol toxicity. We also verify all our analytical results using numerical simulations.

Bose H., Mukherjee S., Li X.

Cutaneous Leishmaniasis (CL) is a neglected tropical complex vector-borne disease which is originated by the protozoa of the genus Leishmania. The disease is transmitted to human or animal through the bites of infected female Phlebotominae sand-fly (vector). This primarily affects the skin, mucous membranes and other internal organs. It is very noteworthy that the dynamic behavior of any living being not only depends on the conditions of its current state but also on those of its previous states . In this article we proposed and analyzed a four- dimensional ratio-dependent mathematical model that includes vector feeding preference of female sand flies for career hosts; additionally, we analyzed the Caputo-Fabrizio fractional version of the basic model to capture the effect of memory in the system. Based on different values of the fractional order $$\tau \in (0, 1)$$ , we compare the behaviour of the fractional-order model with the corresponding integer order model. All of the analytical results are validated through proper numerical simulations and are compared with some real clinical data.

Cao X., Ghosh T., Ghosh S.

Investigation of latency phase and it’s impact in leprosy remains a long-term debate for clinical and experimental scientists. In our research work, we have explicitly introduced the class of latently infected Schwann cells into the mathematical modeling framework along with susceptible Schwann cells, actively infected Schwann cells and $$M.~leprae $$ bacteria to explore the disease dynamics more accurately. Besides performing the stability analysis of the disease-free and endemic equilibriums, we have investigated the optimal control-induced system incorporating two drug therapies, Clofazimine and Dapsone using Pontryagin minimum principle. Optimal therapy shows much optimistic results as it correlates the tenure and drug dose of combined therapy more closely to the real world clinical data-based scenario. Numerical simulations are performed to validate all of our analytic outcomes using Matlab 2016a.

Bhattacharya A.

In this paper it is decided to derive the strong field lensing observables for black hole foils which is considered as the Damour-Solodukhin wormhole and also to examine the range of the deviation parameter λ for which it mimics Schwarzschild black holes in both the classical and quantum level. The lensing observables for the black hole $$Sgr{A}^{*}$$ residing in our galaxy can be interpreted to provide a numerical expression of $$\uplambda \sim {10}^{-3}$$ .

Bag A.K., Chatterjee A.N.

Worldwide, cervical cancer holds the fourth position in terms of prevalence among women, but for India, it is more severe holding the second position across the globe. The majority cases of this disease are exclusively linked with Human Papillomavirus (HPV). In most cases, cervical cancer presents no symptoms, leading to its detection at an advanced stage and resulting in death. Early detection of precancerous changes in infected cervical cells through screening programs helps facilitate timely intervention and treatment. Considering the screening program to be time-dependent, we have developed a four-dimensional mathematical model for cervical cancer prevention. This model provides a realistic mathematical framework about how the screening programs contribute to the reduction of cervical cancer cases. We have checked the positivity and boundedness of our proposed system, determined the basic reproduction number ( $$R_0$$ ) to analyze the stability of the disease-free state, explored the existence condition of endemic equilibrium points, and furthermore, analyzed the stability of the infected steady state. We have validated all the obtained mathematical findings through numerical simulations in MATLAB 2016a.

Aktar S., Rahaman F.

In this paper, we take a rotating traversable axially symmetric wormhole spacetime of the Teo class and investigate several physical properties and characteristics of radiation emerging from the surface of the accretion disks of it. We have studied the marginally stable orbits. We have employed ray-tracing technique to produce the intensity map of the image of an accretion disk in two ways.