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Stochastic models in seed dispersals: random walks and birth-death processes

Abdullahi A, Shohaimi S, Kilicman A, Ibrahim MH

J Biol Dyn, 2019 12;13(1):345-361.
PMID: 31056007 DOI: 10.1080/17513758.2019.1605003

Seed dispersals deal with complex systems through which the data collected using advanced seed tracking facilities pose challenges to conventional approaches, such as empirical and deterministic models. The use of stochastic models in current seed dispersal studies is encouraged. This review describes three existing stochastic models: the birth-death process (BDP), a 2 dimensional (
2

D

) symmetric random walks and a
2

D

intermittent walks. The three models possess Markovian property, which make them flexible for studying natural phenomena. Only a few of applications in ecology are found in seed dispersals. The review illustrates how the models are to be used in seed dispersals context. Using the nonlinear BDP, we formulate the individual-based models for two competing plant species while the cover time model is formulated by the symmetric and intermittent random walks. We also show that these three stochastic models can be formulated using the Gillespie algorithm. The full cover time obtained by the symmetric random walks can approximate the Gumbel distribution pattern as the other searching strategies do. We suggest that the applications of these models in seed dispersals may lead to understanding of many complex systems, such as the seed removal experiments and behaviour of foraging agents, among others.
Switched step integral backstepping control for nonlinear motion systems with application to a laboratory helicopter

Haruna A, Mohamed Z, Efe MÖ, Abdullahi AM

ISA Trans, 2023 Oct;141:470-481.
PMID: 37507325 DOI: 10.1016/j.isatra.2023.07.002

In this paper, the energy efficiency of the widespread application of backstepping control to a class of nonlinear motion systems is investigated. A Switched Step Integral Backstepping Control (SSIBC) scheme is introduced to improve immunity to measurement noise and to increase the energy efficiency of conventional backstepping in practice. The SSIBC is realized by switching between two candidate controllers obtained at different steps of the iterative backstepping design process. A bi-state dependent hysteresis rule is developed to supervise stable switching between the different regimes in the presence of noise. The proposed method is experimentally verified on a MIMO twin rotor laboratory helicopter involving coupled nonlinear dynamics, inaccessible states and uncertainties. Experimental results show that in addition to a reduction in power consumption, the SSIBC reduces saturation of the control signal and visible motor jerking in contrast with conventional backstepping. Additional comparisons with a previously proposed optimized decoupling PID controller also show significant improvement in precision achieved with higher energy efficiency. Experimental results obtained with the introduction of an external disturbance into the system also show the robustness of the proposed SSIBC.
Fulltext Potential of Using Ginger Essential Oils-Based Nanotechnology to Control Tropical Plant Diseases

Abdullahi A, Ahmad K, Ismail IS, Asib N, Ahmed OH, Abubakar AI, et al.

Plant Pathol J, 2020 Dec 01;36(6):515-535.
PMID: 33312089 DOI: 10.5423/PPJ.RW.05.2020.0077

Essential oils (EOs) have gained a renewed interest in many disciplines such as plant disease control and medicine. This review discusses the components of ginger EOs, their mode of action, and their potential nanotechnology applications in controlling tropical plant diseases. Gas chromatography-mass spectroscopy (GC-MS), high-performance liquid chromatography, and headspace procedures are commonly used to detect and profile their chemical compositions EOs in ginger. The ginger EOs are composed of monoterpenes (transcaryophyllene, camphene, geranial, eucalyptol, and neral) and sesquiterpene hydrocarbons (α-zingiberene, ar-curcumene, β-bisabolene, and β-sesquiphellandrene). GC-MS analysis of the EOs revealed many compounds but few compounds were revealed using the headspace approach. The EOs have a wide range of activities against many phytopathogens. EOs mode of action affects both the pathogen cell's external envelope and internal structures. The problems associated with solubility and stability of EOs had prompted the use nanotechnology such as nanoemulsions. The use of nanoemulsion to increase efficiency and supply of EOs to control plant diseases control was discussed in this present paper. The findings of this review paper may accelerate the effective use of ginger EOs in controlling tropical plant diseases.
Prevalence of Enterobius vermicularis among children in Iran: A comprehensive systematic review and meta-analysis

Moussavi E, Houssaini M, Salari N, Hemmati M, Abdullahi A, Khaleghi AA, et al.

Parasite Epidemiol Control, 2023 Aug;22:e00315.
PMID: 37501920 DOI: 10.1016/j.parepi.2023.e00315

BACKGROUND: Parasitic infections are among the most common diseases worldwide, and enterobiasis is a well-known type of parasitic infection in children. Given the existence of several reports on the prevalence of Enterobius vermicularis in different provinces of Iran and the heterogeneity of the reported prevalence data, this study aims to investigate the overall prevalence of Enterobius vermicularis among children in Iran through a systematic review and meta-analysis.
METHODS: This systematic review and meta-analysis study involved a comprehensive search of several databases, including PubMed, ScienceDirect, SID, and Google Scholar, focusing on cross-sectional studies that examined the prevalence of Enterobius vermicularis infection in Iranian children. The identified studies were entered into the EndNote software for review. The quality of observational studies was evaluated using the STROBE checklist. The information extracted from the studies was entered into the Comprehensive Meta-analysis (CMA, Version 2) software. Heterogeneity among the studies was analyzed using the I2 test, and publication bias was assessed using the Egger test and funnel plot.
RESULTS: A total of 51 studies, with a sample size of 46,070 children, were included in the review. Using the random effects method, the overall prevalence of Enterobius vermicularis among children in Iran was determined to be 6.7% (95%CI: 5.2-8.6). The review of the factors affecting study heterogeneity and sample size indicated that as sample size increased, the prevalence of Enterobius vermicularis among children in Iran also increased (p = 0.578). Additionally, with an increase in the year of conducting the studies, the prevalence of Enterobius vermicularis among children in Iran decreased (p
Fulltext Food safety knowledge, attitude, and practice toward compliance with abattoir laws among the abattoir workers in Malaysia

Abdullahi A, Hassan A, Kadarman N, Saleh A, Baraya YS, Lua PL

Int J Gen Med, 2016;9:79-87.
PMID: 27110137 DOI: 10.2147/IJGM.S98436

Foodborne diseases are common in the developing countries due to the predominant poor food handling and sanitation practices, particularly as a result of inadequate food safety laws, weak regulatory structures, and inadequate funding as well as a lack of appropriate education for food-handlers. The most frequently involved foods in disease outbreaks are of animal origin. However, in spite of the adequate legislation and laws governing the abattoir operation in Malaysia, compliance with food safety requirements during meat processing and waste disposal is inadequate. Therefore, the present study was designed to assess the food safety knowledge, attitude, and practice toward compliance with abattoir laws among the workers in Terengganu, Malaysia.
Global Burden of Elevated LDL-C: Findings From the Global Burden of Disease Study 2023

GBD 2023 LDL Cholesterol Collaborators, Razo C, DeCleene NK, Johnson CO, Stark BA, LeGrand K, et al.

JAMA, 2026 Aug 25;336(8):673-698.
PMID: 42525403 DOI: 10.1001/jama.2026.8628

IMPORTANCE: Elevated low-density lipoprotein cholesterol (LDL-C) is a modifiable risk factor for cardiovascular disease, the leading cause of premature death worldwide. Assessing the LDL-C-related burden is critical for guiding prevention and treatment strategies.
OBJECTIVES: To estimate the global, regional, and national burden of ischemic heart disease and ischemic stroke attributable to elevated LDL-C (relative to 35-54 mg/dL) from 1990 to 2023 and to quantify the contributions of population growth, aging, risk-deleted burden, and exposure changes to burden trends.
DESIGN, SETTING, AND POPULATION: This comparative risk assessment, part of the Global Burden of Disease Study 2023, estimated population-level LDL-C exposure and associated health loss in 204 countries and territories. Mean LDL-C levels were estimated using spatiotemporal gaussian process regression based on 806 studies across 161 countries. Relative risks were derived from meta-analyses of 38 randomized clinical trials. Population-attributable fractions for deaths and disability-adjusted life-years (DALYs) were estimated by age and sex for adults aged 25 years or older from 1990 to 2023, with 95% uncertainty intervals.
EXPOSURE: Population-level LDL-C concentrations.
MAIN OUTCOMES AND MEASURES: Population-attributable fractions, counts, and rates (all ages and age standardized per 100 000) of LDL-C-attributable deaths and DALYs from ischemic heart disease and ischemic stroke, with uncertainty intervals.
RESULTS: In 2023, elevated LDL-C accounted for 3.6 million deaths (95% uncertainty interval, 2.2-5.4 million; 6.0% of global mortality) and 90.7 million DALYs (95% uncertainty interval, 58.9-123.3 million; 3.2% of DALYs). Although global all-ages rates remained stable, age-standardized death and DALY rates decreased by 45.6% and 39.5%, respectively, since 1990. In 2023, age-standardized LDL-C-attributable DALY rates were highest in Eastern Europe and lowest in high-income Asia-Pacific. One-third of the global LDL-C burden occurred in India and China. Population growth and aging drove the increasing burden, with notable regional disparities in LDL-C exposure and risk-deleted DALY rates shifting toward middle-sociodemographic settings.
CONCLUSIONS AND RELEVANCE: Despite declining age-standardized rates, the absolute LDL-C burden has increased since 1990 due to demographic changes and has shifted toward middle-sociodemographic countries. Measurement and surveillance gaps persist. Strengthened prevention, diagnosis, and treatment access strategies are essential to mitigate the health burden of LDL-C.