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This study investigates the mechanical, fatigue, water absorption, and flammability properties of polyethylene terephthalate (PET) core-pineapple fiber sandwich composites reinforced with silane-treated neem fruit husk (NFH) biosilica additives. The novel approach includes modifying the fiber’s surface and incorporating biosilica to enhance environmental resistance. The composites were prepared using a hand layup method, followed by silane treatment of the biosilica, pineapple fiber, PET core and vinyl ester resin. Subsequently, to evaluate environmental impacts on composite’s performance, sandwich composites were subjected to temperature aging at 40^∘C and 60^∘C in a hot oven for 30 days and warm water aging at the same temperatures in tap water with pH 7.4. According to the results, adding 1%, 3%, and 5 vol.% silane-treated biosilica significantly improved the mechanical properties. The composite with 3% biosilica (L2) showed a tensile strength of 120.8MPa, flexural strength of 194.4MPa, compression strength of 182.4MPa, rail shear strength of 20.21MPa, ILSS of 23.14MPa, hardness of 85 Shore-D, and Izod impact strength of 6.56 J. Even under temperature and water aging conditions, the composites showed only minimal reductions in properties, highlighting the efficacy of the silane treatment. The temperature-aged L2 composite had a tensile strength of 104MPa, flexural strength of 172.8 MPa, compression strength of 164MPa, and ILSS of 22.5MPa, while the water-aged L2 composite exhibited a tensile strength of 96MPa, flexural strength of 152.8MPa, compression strength of 146.4MPa, and ILSS of 21.4MPa. Scanning electron microscope (SEM) analysis confirmed uniform dispersion of biosilica particles, critical for improved performance, though higher concentrations led to agglomeration and stress points. The composites also demonstrated excellent flame retardancy, maintaining a UL-94 V-0 rating with decreased flame propagation speeds, specifically 9.05mm/min for L2. These findings underscore the potential of silane-treated biosilica as a reinforcing additive to enhance the durability and performance of composites in adverse conditions.

Rotation of the cervical spine beyond its normal range of motion is a leading cause of fall-related spinal cord injuries (SCIs) in older adults. This rotation is constrained, in part, by the spinal ligaments. The experimentally measured properties of these ligaments are tabulated in literature, including sex-specific properties; however, their influence on the rotation kinematics of the cervical spine has not been compared. We examined how different mechanical properties of spinal ligaments, including sex-specific properties, affected the rotational kinematics of the cervical spine using finite element analysis (FEA). Ligament properties most influenced the rotation of the lower cervical spine, with increased ligament stiffness reducing rotation. Ligament deformation remained mostly in the toe region of their force-displacement curves, emphasizing the need to incorporate non-linear ligament behavior in FEA. Predictions made using one set of experimental properties (Property 1) better-matched experimental kinematic data. Using sex-specific properties had a moderate effect (6% in extension, –3% in flexion) on rotation, with a greater impact on extension. Ligament properties also affected the segmental distribution of rotation, causing a variability of 3–21% at different levels. We emphasized the need to incorporate tailored approaches to FEA to obtain clinically relevant results when modeling flexion/extension rotation.

Background: Aging is a complex biological process and is characterized by a gradual decline in physiological functions and increased vulnerability to various diseases. It is linked with the genes known as Monocyte Chemoattractant Protein-1 (MCP-1) and Vascular Endothelial Growth Factor (VEGF). MCP-1 is a key protein in generating immune response and VEGF is involved in angiogenesis. Objectives: This is a cross-sectional experimental study that aims to observe interplay between MCP-1 SNP (rs1024611) and VEGF SNP (rs699947) with aging and lifestyle habits. It delves into the biological pathways implicated in aging, as well as the impact of lifestyle elements such as dietary habits, tobacco use and physical activity on MCP-1 and VEGF expression levels. Method: The study involved the selection of 60 samples from elderly individuals and 60 samples from healthy individuals as control. The selection process was done by filling the proforma having questions related to the lifestyle habits and the use of medication since they can interfere with gene functioning. After that DNA extraction, and the identification of gene presence through PCR analysis. The assessment of PCR outcomes revealed a prevalence of the CC allele in both the experimental and control cohorts for both MCP-1 and VEGF, highlighting the critical role of these genes in the aging process. Furthermore, it posits that variations in the VEGF gene may hold significant sway over aging. Bioinformatics techniques were used to explore the relationship between MCP-1 and VEGF, employing Cytoscape STRING, KEGG pathway analysis and GO enrichment to analyze the interactions between these two genes. Results: It was observed that these genes are interconnected, functioning under the influence of the Tp65 transcriptional factor. The research findings also put forth the notion that dietary habits and physical exercise could potentially modulate the expression of these genes, thereby influencing the process of healthy aging. Those who adopted healthy lifestyle showed CC and TT genotypes for MCP-1 and VEGF respectively therefore, showing slow and healthy aging. Conclusions: The conclusion of this article suggests that the MCP-1 and VEGF genes play a crucial role in immune response, inflammation and aging. The study highlights the potential interaction between these genes in monocyte recruitment and angiogenesis.

Developing Asia has grown faster than other parts of the world for decades. However, population aging is expected to pose significant headwinds to the region’s future economic growth. We update and enhance the analysis of Park and Shin (2012) to project the impact of population aging on developing Asia’s growth between 2021 and 2050. Our projections indicate that a demographic transition will have a substantial negative effect on the region’s future growth, but the effect varies across economies. Older economies will suffer a demographic tax, whereas younger economies will continue to enjoy a positive but declining demographic dividend.

This paper uses two methodologies to explore the extent to which greater labor force participation among older Malaysians can expand Malaysia’s labor supply. The Milligan–Wise method estimates the potential to increase the labor force participation rate of older Malaysians by estimating how much they would work if they were to work as much as those with the same mortality rate in the past. The Cutler, Meara, and Richards-Shubik (2013) method estimates the same potential by estimating how much older Malaysians would work if they worked as much as their younger counterparts in similar health. We made further simulations to quantify the capacity of older Malaysians to work after they are 60 years old. The results show significant additional work capacity among older people in Malaysia, particularly males, urban dwellers, and those with low educational attainment.

The People’s Republic of China is aging rapidly at one of the most rapid paces in the world. The resulting decline in the share of the population that is of working age creates challenges for both the economy and society, making it relevant to explore the health capacity to work among older persons. Using census data and data from the China Health and Retirement Longitudinal Study, this paper applies two widely used methods to estimate the additional health capacity to work. The results confirm large untapped work capacity in the population of older persons, but the additional health capacity to work is unevenly distributed among different groups: Women and urban residents have more additional work capacity than men and older persons in rural areas. Pension systems and variation in types of work contribute to the urban–rural difference.

In this paper the Penna bit-string model of biological aging with different lengths of bit-strings genome is considered. We show from computer simulation that changes in genome length may be crucial for determining population characterization and seem to be irreversible by scaling the other model control parameters.

We derive catastrophic senescence of the Pacific salmon from an aging model which was recently proposed by Stauffer. The model is based on the postulates of a minimum reproduction age and a maximal genetic lifespan. It allows for self-organization of a typical age of first reproduction and a typical age of death. Our Monte Carlo simulations of the population dynamics show that the model leads to catastrophic senescence for semelparous reproduction as it occurs in the case of salmon, to a more gradually increase of senescence for iteroparous reproduction.

It is shown that if the computer model of biological aging proposed by Stauffer is modified such that the late reproduction is privileged, then the Gompertz law of exponential increase of mortality can be retrieved.

We use a simple model for biological aging to study the mortality of the population, obtaining a good agreement with the Gompertz law. We also simulate the same model on a square lattice, considering different strategies of parental care. The results are in agreement with those obtained earlier with the more complicated Penna model for biological aging. Finally, we present the sexual version of this simple model.

To analyze aging processes, a concept based on these hypotheses was utilized: maturation and aging are affected by external influences and are related to the system's ability to learn, to adapt to sudden environmental changes rapidly and survive. To simulate the maturation and aging processes of systems, individuals and populations, a perceptron to classify two notably different classification tasks was trained. After lengthy training to learn the first task, the magnitudes of the perceptron's weights increase. The presence of nonlinearity in the output of the perceptron causes a saturation of the cost function. Saturation reduces the capability to learn a new task rapidly. The aging curves obtained show a rise and fall character. Factors that can be utilized to control re-training curves were considered. A new model allows us to analyze the aging process as a natural phenomenon that helps populations to survive in everlastingly changing environments was also introduced.

We introduce into the Penna Model of biological aging a mechanism to maximize the ability of a sperm to compete with those of other males. Such a selfish mechanism increases the rate of success of male reproduction, but may decrease the survival probability of the female population, depending on its mode of action. We also find a dynamic phase transition induced by the existence of an absorbing state, where no selfish males survive.

In this work we study, by means of numerical simulations, the out-of-equilibrium dynamics of the one-dimensional Edwards–Anderson model with long-range interactions of the form ± Jr^-α. In the limit α → 0 we recover the well known Sherrington–Kirkpatrick mean-field version of the model, which presents a very complex dynamical behavior. At the other extreme, for α → ∞ the model converges to the nearest-neighbor one-dimensional system. We focus our study on the dependence of the dynamics on the history of the sample (aging phenomena) for different values of α. The model is known to have mean-field exponents already for values of α = 2/3. Our results indicate that the crossover to the dynamic mean-field occurs at a value of α < 2/3.

Using a lattice model based on Monte Carlo simulations, we study the role of the reproduction pattern on the fate of an evolving population. Each individual is under the selection pressure from the environment and random mutations. The habitat ("climate") is changing periodically. Evolutions of populations following two reproduction patterns are compared, asexual and sexual. We show, via Monte Carlo simulations, that sexual reproduction by keeping more diversified populations gives them better chances to adapt themselves to the changing environment. However, in order to obtain a greater chance to mate, the birth rate should be high. In the case of low birth rate and high mutation probability there is a preference for the asexual reproduction.

In the Sznajd consensus model on the square lattice, two people who agree in their opinions convince their neighbors of this opinion. We generalize it to many layers representing many age levels, and check if a consensus among all layers is possible. Advertising sometimes, but not always, produces a consensus on the advertised opinion.

We model the evolution of a population on a 2D cellular automata (CA) lattice. Every individual holds a binary "genetic code". The code length and the number of "1"s in the chain correspond to the maximal and actual life-time of individual, respectively. The "genetic code" code is divided onto three life-episodes: "youth", "maturity" and "old age". Only "mature" individuals can procreate. We investigate the duration of the life-episodes and their role in protecting the population from extinction in hostile environments. We observe that in the stable environment, which does not influence the life-time of individuals, the "youth" and the "maturity" periods extend extremely long during evolution, while the "old age" remains short. The situation is different for hostile plaque-like conditions. Under these circumstances, the "youth" period vanishes, while the longer "old age" period stabilizes the population growth, increases its average age and thereby increases its chance of survival. We can conclude that the idle life-episodes set up the control mechanisms, which allow for self-adaptation of the population to varying environmental conditions.

Recently, individual-based models originally used for biological purposes revealed interesting insights into processes of the competition of languages. Within this new field of population dynamics a model considering sexual populations with aging is presented. The agents are situated on a lattice and each one speaks one of two languages or both. The stability and quantitative structure of an interface between two regions, initially speaking different languages, is studied. We find that individuals speaking both languages do not prefer any of these regions and have a different age structure than individuals speaking only one language.

We present some simulations results of population growth and evolution, using the standard asexual Penna model, with individuals characterized by a string of bits representing a genome containing some possible mutations. After about 20 000 simulation steps, when only a few genetic families are still present from among rich variety of families at the beginning of the simulation game, strong peaks in mutation distribution functions are observed. This known effect is due to evolution rules with hereditary mechanism. The birth and death balance in the simulation game also leads to elimination of families specified by different genomes. The number of families G(t) versus time t follow the power law, G∝tⁿ. Our results show the power coefficient exponent n is changing with time. Starting from about -1, smoothly achieves about -2 after hundreds of steps, and finally has semi-smooth transition to 0, when only one family exists in the environment. This is in contrast with constant n about -1 as found, for example, in Ref. 1. We suspect that this discrepancy may be due to two different time scales in simulations — initial stages follow the n ≈ -1 law, yet for large number of simulation steps we get n ≈ -2, provided the random initial population was sufficiently big to allow for still reliable statistical analysis. The n ≈ -1 evolution stage seems to be associated with the Verhulst mechanism of population elimination due to the limited environmental capacity — when the standard evolution rules were modified, we observed a plateau (n =0) in the power law in short time scale, again followed by n ≈ -2 law for longer times. The modified model uses birth rate controlled by the current population instead of the standard Verhulst death factor.

The understanding of language competition helps us to predict extinction and survival of languages spoken by minorities. A simple agent-based model of a sexual population, based on the Penna model, is built in order to find out under which circumstances one language dominates other ones. This model considers that only young people learn foreign languages. The simulations show a first order phase transition of the ratio between the number of speakers of different languages with the mutation rate as control parameter.

The collaboration network is an example of a social network which has both non-trivial temporal and spatial dependence. Based on the observations of collaborations in Physical Review Letters, a model of collaboration network is proposed which correctly reproduces the time evolution of the link length distributions, clustering coefficients, degree distributions, and assortative property of real data to a large extent.