Search results for: fish population dynamics

Authors: Ali F. Al-Baz, Mohsen M. Al-Husaini, James M. Bishop

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Intertidal fixed stake net trap (hadrah) is one of the oldest fishing gears used throughout the Arabian Gulf countries since 1800s and also one of most efficient methods of capturing fish from the intertidal area. This study described the hadrah fishery in Kuwait. From October 2001 to December 2002, more than 37,372 specimens representing 95 species (89 fish, 2 mollusks, 4 crustaceans) were measured from hadrah located in three different areas along Kuwait's coast. In Kuwait Bay, catch rates averaged 62 kg/sir day (range 14 kg/sir-day in February to 160 kg/sir-day in October 2002). Commercial species accounted for 41% of the catches. Catches from Failakah Island averaged 96 kg/sir-day from June through September, with 61% of the catch being commercial species. In the southern area, catches averaged only 32 kg/sir-day, and only 34% were commercially important. Forty percent of the hadrah catches were juveniles which shows that the shallow intertidal waters are prime nursery habitat, particularly in Kuwait Bay. To maintain ecosystem biodiversity and recruitment success of the fishes, we recommended that all hadrah should be removed from Kuwait Bay. In the future, removal of hadrah in other locations should be considered.

Keywords: catch and effort, hadrah, intertidal fixed stake net, Kuwait, species composition

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Authors: Beata Jackowska-Zduniak

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We formulate and analyze a mathematical model describing dynamics of cancer growth under the influence of radiation therapy. The effect of this type of therapy is considered as an additional equation of discussed model. Numerical simulations show that delay, which is added to ordinary differential equations and represent time needed for transformation from one type of cells to the other one, affects the behavior of the system. The validation and verification of proposed model is based on medical data. Analytical results are illustrated by numerical examples of the model dynamics. The model is able to reconstruct dynamics of treatment of cancer and may be used to determine the most effective treatment regimen based on the study of the behavior of individual treatment protocols.

Keywords: mathematical modeling, numerical simulation, ordinary differential equations, radiation therapy

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Authors: José Carlos Rodríguez, Mario Gómez, Medardo Serna

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This paper analyses managing higher education institutions in emerging economies. The paper investigates the case of postgraduate studies development at public universities. In so doing, it adopts the complex theory approach to evaluate how postgraduate studies have evolved in these countries. The investigation suggests that the postgraduate studies sector at public universities can be seen as a complex adaptive system (CAS). Therefore, the paper adopts system dynamics (SD) methods to develop this analysis. The case of postgraduate studies at Universidad Michoacana de San Nicolás de Hidalgo in Mexico is investigated in this paper.

Keywords: complex adaptive systems, higher education institutions, Mexico, system dynamics

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Authors: Gayathri Vijayakumar, Preethi Baskaran

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The effluents that are let down by the industries mix with the water bodies and drastically affect the aquatic life, which leads to pollution and bio magnifications. Effluents mostly contain chemicals, heavy metals etc., and cause toxicity to the environment. The pharmaceutical industries too contribute. The by-products and other unwanted waste are discharged without any treatment; these causes DNA damage and affect behavior of aquatic life. The study was conducted on koi carp (Cyprinus carpio) the ornamental variety of common carp. A two week long study was conducted on them using common anti-depressant drug (Diazepam) in various concentrations. These drugs are known to cause behavioral damage and organ malfunctions (muscle twitch). The histopathological study conducted showed permanent muscle twitching and lesions in the fish samples studied. The sociability was also affected in the span of 14 days. Higher concentrations of this drug showed severe damage in the muscle structures. Thus, this drug can cause adverse effects on marine ecosystem and eventually cause bio magnification of drug by running through the food chain.

Keywords: pollution, toxicity, bio-magnifications, koi carp, muscle twitch, diazepam, histopathology

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Authors: Watchawin Ekphinitphithaya, Patompong Satapornpong

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Introduction: Carbamazepine (CBZ) is one of the most prescribed antiepileptic drugs (AEDs) by neurologists and non-neurologist worldwide. CBZ is usually prescribed along with other drugs, leading to the possibility of severe cutaneous adverse drug reactions (SCARs). The HLA-B*15:02 is strongly associated with CBZ-induced Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS–TEN) in the Han Chinese and other Asian populations but not in European populations, while HLA-A*31:01 allele has been reported to be associated with CBZ-induced SCARs in European population and Japanese. Objective: The aim of this study is to investigate the distribution of pharmacogenetics HLA-A*31:01 marker in a healthy Thai population associated with Carbamazepine-induced SCARs. Materials and Methods: Prospective study, 350 unrelated healthy Thais were recruited in this study. Human leukocyte antigen-A alleles were genotyped using PCR-sequence specific oligonucleotides (PCR-SSOs). Results: The frequency of HLA-A alleles were HLA-A*11:01 (190 alleles, 27.14%), HLA-A*24:02 (82 alleles, 11.71%), HLA-A*02:03 (80 alleles, 11.43%), HLA-A*33:03 (76 alleles, 10.86%), HLA-A*02:07 (58 alleles, 8.29%), HLA-A*02:01 (35 alleles, 5.00%), HLA-A*24:07 (29 alleles, 4.14%), HLA-A*02:06 – HLA-A*30:01 (15 alleles, 2.14%), and HLA-A*01:01 (14 alleles, 2.00%). Particularly, the number of HLA-A*31:01 alleles was 6 of 700 (0.86%) in the healthy Thai population. Many research presented varying distributions of HLA-A*31:01 in Asians, including 2% of Han Chinese, 9% of Japanese and 5% of Koreans. In addition, this allele was found approximately 2-5% in the Caucasian population. Conclusions: Thus, the pharmacogenetics database is vital to support in many populations, especially in Thais, for screening HLA-A*31:01 allele to avoid CBZ-induced SCARs before initiating treatments in each population.

Keywords: Carbamazepine, HLA-A*31:01, Thai population, pharmacogenetics

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Authors: Yichao Liu, Peter Fransson, Julian Heidecke, Jonas Wallin, Joacim Rockloev

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Dengue, a mosquito-borne viral disease, poses a significant public health challenge in endemic tropical or subtropical countries, including Sri Lanka. To reveal insights into the complexity of the dynamics of this disease and study the drivers, a comprehensive model capable of both robust forecasting and insightful inference of drivers while capturing the co-circulating of several virus strains is essential. However, existing studies mostly focus on only one aspect at a time and do not integrate and carry insights across the siloed approach. While mechanistic models are developed to capture immunity dynamics, they are often oversimplified and lack integration of all the diverse drivers of disease transmission. On the other hand, purely data-driven methods lack constraints imposed by immuno-epidemiological processes, making them prone to overfitting and inference bias. This research presents a hybrid model that combines machine learning techniques with mechanistic modelling to overcome the limitations of existing approaches. Leveraging eight years of newly reported dengue case data, along with socioeconomic factors, such as human mobility, weekly climate data from 2011 to 2018, genetic data detecting the introduction and presence of new strains, and estimates of seropositivity for different districts in Sri Lanka, we derive a data-driven vector (SEI) to human (SEIR) model across 16 regions in Sri Lanka at the weekly time scale. By conducting ablation studies, the lag effects allowing delays up to 12 weeks of time-varying climate factors were determined. The model demonstrates superior predictive performance over a pure machine learning approach when considering lead times of 5 and 10 weeks on data withheld from model fitting. It further reveals several interesting interpretable findings of drivers while adjusting for the dynamics and influences of immunity and introduction of a new strain. The study uncovers strong influences of socioeconomic variables: population density, mobility, household income and rural vs. urban population. The study reveals substantial sensitivity to the diurnal temperature range and precipitation, while mean temperature and humidity appear less important in the study location. Additionally, the model indicated sensitivity to vegetation index, both max and average. Predictions on testing data reveal high model accuracy. Overall, this study advances the knowledge of dengue transmission in Sri Lanka and demonstrates the importance of incorporating hybrid modelling techniques to use biologically informed model structures with flexible data-driven estimates of model parameters. The findings show the potential to both inference of drivers in situations of complex disease dynamics and robust forecasting models.

Keywords: compartmental model, climate, dengue, machine learning, social-economic

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Authors: Chloé Kernaléguen, Laura Kundun, Tessie Lery, Ryan Laleg, Zhangyun Tan

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This study explores global disparities in respiratory syncytial virus (RSV) bronchiolitis incidence among children aged 0-2 years, focusing on the human development index (HDI) as a key determinant. RSV bronchiolitis poses a significant health risk to young children, influenced by factors, including socio-economic conditions captured by the HDI. Through a comprehensive systematic review and dataset selection (Switzerland, Brazil, United States of America), we formulated an HDI-SEIRS numerical model within the SEIRS framework. Results show variations in RSV bronchiolitis dynamics across countries, emphasizing the influence of HDI. Modelling reveals a correlation between higher HDI and increased bronchiolitis spread, notably in the USA and Switzerland. The ratios HDIcountry over HDImax strengthen this association, while climate disparities contribute to variations, especially in colder climates like the USA and Switzerland. The study raises the hypothesis of an indirect link between higher HDI and more frequent bronchiolitis, underlining the need for nuanced understanding. Factors like improved healthcare access, population density, mobility, and social behaviors in higher HDI countries might contribute to unexpected trends. Limitations include dataset quality and restricted RSV bronchiolitis data. Future research should encompass diverse HDI datasets to refine HDI's role in bronchiolitis dynamics. In conclusion, HDI-SEIRS models offer insights into factors influencing RSV bronchiolitis spread. While HDI is a significant indicator, its impact is indirect, necessitating a holistic approach to effective public health policies. This analysis sets the stage for further investigations into multifaceted interactions shaping bronchiolitis dynamics in diverse socio-economic contexts.

Keywords: bronchiolitis propagation, HDI influence, respiratory syncytial virus, SEIRS model

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Authors: Mohamed Hamed Mohamed Ahmed Alameer

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Population studies, essentially deals with the size, growth, and distribution of the population in a given area. Size, growth, and distribution are determined by three major factors, which are fertility mortality, and migration. Of these factors, fertility- as a number of live births a woman has actually had- is a potent socio-demographic force in vital process of population growth. So, fertility is a major component of population growth. It is one of the main determinants of population growth and has crucial role in population dynamic, because it measures the rate at which a population increased. In fact the levels of fertility are vary widely among nations, countries, geographic regions, ethnic, socio- economic groups, and religious groups. Fertility differential by religion have been empirically documented in a large numbers of countries. For instance, many researchers in developing and developed countries investigated the differential of fertility among Muslims and Non- Muslims. Most of them have found that fertility of Muslims is higher than fertility of non Muslims. And Muslims have a tendency for large families comparing to non- Muslims population. On the basis of this; Islam by it itself could play an important role in shaping attitudes and values of fertility, such as: sustainability of human kind, developmental reasons, religious Motivations, socioeconomic Motivations, and Psychological Motivation. Therefore, this paper investigates socio-economic values of fertility in Islam and compare it to Malthusian and neo Malthusian functionalists and conflict perspectives.

Keywords: islam, fertility, socioeconomic values, social sciences

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Authors: Hasanzade Nazenin, Hasanova Naila

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According to the WHO, osteoporosis is one of the most important health problems in the world and occupies the 4th place in its importance after cardiovascular pathology, oncological diseases and diabetes mellitus. The significance of osteoporosis is determined by its prevalence among the population, the severity of the course, the cause of death, disability, reduced quality of life, high economic costs for prevention and treatment. Osteoporosis is a systemic skeletal disease characterized by a decrease in bone mass and a violation of the structure of bone tissue, leading to an increase in bone fragility and the risk of fractures. Osteoporosis is manifested by low-traumatic fractures. Due to the complexity of the recovery process, the treatment of osteoporotic fractures is one of the important problems of modern traumatology. Diagnostic markers are needed to monitor the recovery period. Human cartilage glycoprotein -39, which has been studied so far in inflammatory processes in the bones, may allow the development of the correct treatment regimen, reflecting the level of metabolic processes in the bone tissue. The study was performed to examine the dynamics of human cartilage glycoprotein-39 (HCgp39) in the blood serum during osteoporosis and fracture healing. The material of the study is formed by the examination results of 68 people aged 38-83. Group I - control group consisted of 14 practically healthy people, group II - 14 patients with osteoporosis, group III - 15 patients with non-osteoporotic fractures, group IV - 25 patients with osteoporotic fractures. In groups, they were analyzed by enzyme-linked immunosorbent assay 3 times during the first month. As a result, in the first month of the recovery period, no significant difference was observed in the HCgp39 dynamics for groups II and IV (p> 0.05). However, there was a significant reduction in group III (p <0.05). As no osteoporotic changes were observed in this patient group, bone healing was rapid and it was possible to monitor the dynamics of HCgp39 changes within 1 month. Patients with osteoporosis and other bone fractures in the process of complete recovery need to study HCgp39 more as a diagnostic indicator.

Keywords: osteoporosis, osteoporotic fractures, human cartilage glycoprotein, HCgp39

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Authors: Ishiyaku Abdulkadir, Satish Kumar J

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Land Productivity is a measure of the greenness of above-ground biomass in health and potential gain and is not related to agricultural productivity. Monitoring land productivity dynamics is essential to identify, especially when and where the trend is characterized degraded for mitigation measures. This research aims to monitor the land productivity trend of Gombe State between 2001 and 2015. QGIS was used to compute NDVI from AVHRR/MODIS datasets in a cloud-based method. The result appears that land area with improving productivity account for 773sq.km with 4.31%, stable productivity traced to 4,195.6 sq.km with 23.40%, stable but stressed productivity represent 18.7sq.km account for 0.10%, early sign of decline productivity occupied 5203.1sq.km with 29%, declining productivity account for 7019.7sq.km, represent 39.2%, water bodies occupied 718.7sq.km traced to 4% of the state’s area.

Keywords: above-ground biomass, dynamics, land productivity, man-environment relationship

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Authors: Ehsan Ahmadifar, Mohammad Ali Yousefi, Zahra Roohi

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In this study, the effects of different levels of Ergosan (control group (0), 2, 4 and 6 gr Ergosan per Kg diet) as a nutritional supplement were investigated on growth indices and stress in Zebrafish for 3 months. Larvae (4-day-old after hatching) were fed with experimental diet from the beginning of feeding until adult (adolescence) (average weight: 69.3 g, length: 5.1 cm). Different levels of Ergosan had no significant effect on rate survival (P < 0.05). The results showed that diet containing 6 gr Ergosan significantly caused the best FCR in Zebrafish (P < 0.05). By increasing the Ergosan diet, specific growth rate increased. Body weight gain and condition factor had significant differences (P < 0.05) as the highest and the lowest were observed in treatment 3 gr of Ergosan and control, respectively. The results showed that fish fed with experimental diet, had the highest resistance to environmental stresses compared to control, and the test temperature, oxygen, salinity and alkalinity samples containing 6 gr/kg, was significantly more resistance compared to the other treatments (P < 0.05). Overall, to achieve high resistance to environmental stress and increase final biomass using 6 gr/kg Ergosan in diet fish Zebrafish.

Keywords: Ergosan, stress, growth performance, Danio rerio

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Authors: Hassan Alhoujeiri, Angele Matrat, Sandra Beaufort, Claire joaniss Cassan, Jerome Silvester

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Aquaponics is a sustainable food production technology, and its transition to industrial-scale systems has created several challenges that require further investigation in order to make it a robust process. One of the critical concerns is the potential accumulation of compounds from veterinary treatments, phytosanitary agents, fish feed, or simply from contaminated water sources. The accumulation of these substances could negatively impact fish health, microbial biofilters, and plant growth, thereby disrupting the system’s overall balance and functionality. The lack of legislation and knowledge regarding the presence of such compounds in aquaponic systems raises concerns about their potential impact on both system balance and food safety. In this study, we focused on the effects of oxytetracycline (OTC), an antibiotic commonly used in aquaculture, on both the microbial biofilter and plant growth. Although OTC is rarely applied in aquaponics today, the fish compartment may need to be isolated from the system during treatment, as it inhibits specific bacterial populations, which could affect the microbial biofilter's efficiency. However, questions remain about the aquaponic system's tolerance threshold, particularly in cases of treatment or residual OTC traces post-treatment. This study results indicated a decline in microbial biofilter activity to 20% compared to the control, potentially corresponding to treatments of 41 mg/L of OTC. Analysis of microbial populations in the biofilter, using flow cytometry and microscopy (confocal and scanning electron microscopy), revealed an increase in bacterial mortality without disrupting the microbial biofilm. Additionally, OTC exposure led to noticeable changes in plant morphology (e.g., color) and growth, though it did not fully inhibit development. However, no significant effects were observed on seed germination at the tested concentrations despite a measurable impact on subsequent plant growth.

Keywords: aquaponic, oxytetracycline, nitrifying biofilter, plant, micropollutants, sustainability

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Authors: Lessly Borja, Anthony Gualli, Kelly Baño, Fabricio Santacruz

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In this article, a prototype of underwater communication using a long-range laser (50mW) has been carried out in two aquatic scenarios (fish tank and swimming pool) with the aim of recreating Aqua-Fi technology (the future of underwater communications) using a Bluetooth connection to the transmitter to send data in ASCII code by means of light. Initially, the transmitter and receiver circuits were programmed in Arduino so that the data would travel by light pulses in the aforementioned code. To obtain the results of the underwater communication, two scenarios were chosen (fish tank and swimming pool), where the power value of the received signal was calculated from its peak-to-peak voltage using the Oscilloscope equipment (ESPOCH). Finally, it was concluded that the maximum communication range of this prototype is 12m underwater, and it was observed that the power decreases as the distance increases. However, this prototype still needs to improve communication so that the information is not distorted or lost when there is movement and dispersion of the water. It is hoped that it will form the basis for future research.

Keywords: prototype, underwater, communication, power, voltage, distance

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Authors: Quy Dang Nguyen, Reza Nakhaie Jazar

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The paper investigates vibration dynamics of tire-road separation for a quarter-car model; this separation model is developed to be close to the real situation considering the tire is able to separate from the ground plane. A set of piecewise linear mathematical models is developed and matches the in-contact and no-contact states to be considered as mother models for further investigations. The bound dynamics are numerically simulated in the time response and phase portraits. The separation analysis may determine which values of suspension parameters can delay and avoid the no-contact phenomenon, which results in improving ride comfort and eliminating the potentially dangerous oscillation. Finally, model verification is carried out in the MSC-ADAMS environment.

Keywords: quarter-car vibrations, tire-road separation, separation analysis, separation dynamics, ride comfort, ADAMS validation

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Authors: Yetunde I. Bulu, Moses B. Adewole, Julius O. Faluyi

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This study investigates the effect of aggressive application of herbicide on weed succession in an urban environment in Ile-Ife, Osun State. An inspection of the communities was carried out to identify sites maintained by herbicides (test plots) and those without herbicide history (control plots). Four different experimental plots located at Olasode, Eleweran, Ife City and Parakin within Ile-Ife town were monitored during the study. Comprehensive enumeration and identification of plant populations to species level was carried out on each of the plots and at every visit to determine the direction of succession. Index of similarities was used to determine the relationship in plant species composition between plots treated with herbicide and the untreated plots. The trend of increasing plant species was observed in all the study plots. Low Similarity Index between the treated plots and the control vegetation was observed at all visitations. Low similarity was also observed between the above-ground vegetation and the seed bank in all the plots. The study concluded that the weed population observed from the experimental plots showed an increase in species richness and diversity when the plots were left to recover compared to the control plots.

Keywords: herbicide, index of similarity, population, soil seed bank, succession

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Authors: W. T. Hsu, H. L. Tsai

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The rapid aging of the population is a common trend in the world. However, the progress of modern medical technology has increased the average life expectancy. The global population structure has changed dramatically, and the elderly population has risen rapidly. In the face of rapid population growth, it must be noted issues of the aging population must face up to, which are the physiological, psychological, and social problems associated with aging. This study aims to investigate how insurance agents are actively dealing with an aging society, their own aging anxiety, and their exercise habits. Purposive sampling was the sampling method of this study, a total of 204 respondents were surveyed and 204 valid surveys were returned. The returned valid ratio was 100%. Statistical method included descriptive statistics, t-test, and one-way ANOVA. The results of the study found that the insurance agent’s age, seniority, exercise habits to aging anxiety are significantly different.

Keywords: insurance practitioners, aging anxiety, exercise habits, elderly

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Authors: Cheng-Yen Lu, Chin-Yuan Hsu

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Ambient temperature reduction (ATR) can extend the lifespan of an annual fish (Nothobranchius rachovii), but the underlying mechanism is unknown. In this study, the expression, concentration, and activity of cellular-degraded molecules were evaluated in the muscle of N. rachovii reared under high (30 °C), moderate (25 °C), and low (20 °C) ambient temperatures by biochemical techniques. The results showed that (i) the activity of the 20S proteasome, the expression of microtubule-associated protein 1 light chain 3-II (LC3-II), the expression of lysosome-associated membrane protein type 2a (Lamp 2a), and lysosome activity increased with ATR; (ii) the expression of the 70 kD heat shock cognate protein (Hsc 70) decreased with ATR; (iii) the expression of the 20S proteasome, the expression of lysosome-associated membrane protein type 1 (Lamp 1), the expression of molecular target of rapamycin (mTOR), the expression of phosphorylated mTOR (p-mTOR), and the p-mTOR/mTOR ratio did not change with ATR. These findings indicated that ATR activated the activity of proteasome, macroautophagy, and chaperone-mediated autophagy. Taken together these data reveal that ATR likely activates cellular degradation activity to extend the lifespan of N. rachovii.

Keywords: ambient temperature reduction, autophagy, degradation activity, lifespan, proteasome

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Authors: M. Ahmed Eldesouky, S. Nasr, A. Beltagy

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Groundwater is generally considered as the best source for aquaculture as it is well protected from contamination. The most common problem limiting the use of groundwater in Egypt is its high iron, manganese and ammonia content. This problem is often overcome by applying the treatment before use. Aeration in many cases is not enough to oxidize iron and manganese in complex forms with organics. Most of the treatment we use potassium permanganate as an oxidizer followed by a pressurized closed green sand filter. The aim of present study is to investigate the optimum characteristics of groundwater to give lowest iron, manganese and ammonia, maximum production and quality of fish in aquaculture in El-Max Research Station. The major design goal of the system was determined the optimum time for harvesting the treated water, pH, and Glauconite weight to use it for aquaculture process in the research site and achieve the Egyptian law (48/1982) and EPA level required for aquaculture. The water characteristics are [Fe = 0.116 mg/L, Mn = 1.36 mg/L,TN = 0.44 mg/L , TP = 0.07 mg/L , Ammonia = 0.386 mg/L] by using the glauconite filter we obtained high efficiency for removal for [(Fe, Mn and Ammonia] ,but in the Lab we obtained result for (Fe, 43-97), ( Mn,92-99 ), and ( Ammonia, 66-88 )]. We summarized the results to show the optimum time, pH, Glauconite weight, and the best model for design in the region.

Keywords: aquaculture, ammonia in groundwater, groundwater, iron and manganese in water, groundwater treatment

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Authors: Rajat Kapoor

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India is a developing country and has experienced a rapid and tumultuous urban growth in the 20th century. The total urban population of the city increased ten-fold between 1901 and 2001. The share of urban population to the total population increased from less than 11 percent to over 28 percent in the same period. Except few examples, most of the Indian cities have grown in a haphazard manner; concentration of population followed by the planning exercises. In this era of global competitiveness and rapid urbanization there is no scope for malpractices in development strategies. It is expected that the Indian cities shall be planned comprehensively and holistically. The study reveals the land transformations the city of Faridabad is witnessing due to development which is largely boosted by the virtue of its location in the Delhi NCR.

Keywords: Delhi NCR, Faridabad, urban growth patterns, India

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Authors: Abdallah H. Ramini, Alwathiqbellah I. Ibrahim, Mohammad I. Younis

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We investigate experimentally and theoretically the dynamics of a capacitive resonator under mixed frequency excitation of two AC harmonic signals. The resonator is composed of a proof mass suspended by two cantilever beams. Experimental measurements are conducted using a laser Doppler Vibrometer to reveal the interesting dynamics of the system when subjected to two-source excitation. A nonlinear single-degree-of-freedom model is used for the theoretical investigation. The results reveal combination resonances of additive and subtractive type, which are shown to be promising to increase the bandwidth of the resonator near primary resonance frequency. Our results also demonstrate the ability to shift the combination resonances to much lower or much higher frequency ranges. We also demonstrate the dynamic pull-in instability under mixed frequency excitation.

Keywords: electrostatically actuated resonator, multi-frequency excitation, nonlinear dynamics, AC harmonic signals

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Authors: Maurice A. Duka, Leobel Von Q. Tamayo, Niño Carlo I. Casim

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The paucity of long-term measurements and monitoring of accurate water quality parameter profiles is evident for small and deep tropical lakes in Southeast Asia. This leads to a poor understanding of the stratification and mixing dynamics of these lakes in the region. The water quality dynamics of Sampaloc Lake, a tropical crater lake (104 ha, 27 m deep) in the Philippines, were investigated to understand how monsoon-driven conditions impact water quality and ecological health. Located in an urban area with approximately 10% of its surface area allocated to aquaculture, the lake is subject to distinct seasonal changes associated with the Northeast (NE) and Southwest (SW) monsoons. NE Monsoon typically occurs from October to April, while SW monsoon from May to September. These monsoons influence the lake’s water temperature, dissolved oxygen (DO), chlorophyll-α (chl-α), phycocyanin (PC), and turbidity, leading to significant seasonal variability. Monthly field observations of water quality parameters were made from October 2022 to September 2023 using a multi-parameter probe, YSI ProDSS, together with the collection of meteorological data during the same period. During the NE monsoon, cooler air temperatures and winds with sustained speeds caused surface water temperatures to drop from 30.9 ºC in October to 25.5 ºC in January, resulting in the weakening of stratification and eventually in lake turnover. This turnover redistributed nutrients from hypolimnetic layers to surface layers, increasing chl-α and PC levels (14-41 and 0-2 µg/L) throughout the water column. The fish kill was also observed during the lake’s turnover event as a result of the mixing of hypoxic hypolimnetic waters. Turbidity levels (0-3 NTU) were generally low but showed mid-column peaks in October, which was linked to thermocline-related effects, while low values in November followed heavy rainfall dilution and mixing effects. Conversely, the SW monsoon showed increased surface temperatures (28-30 ºC), shallow thermocline formations (3-11 m), and lower surface chl-α and PC levels (2-8 and 0-0.5 µg/L, respectively), likely due to limited nutrient mixing and more stable stratification. Turbidity was notably higher also in July (11-15 NTU) due to intense rainfall and reduced light penetration, which minimized photosynthetic activity. The SW monsoon also coincided with the typhoon season in the study area, resulting in partial upwelling of nutrients during strong storm events. These findings emphasize the need for continued monitoring of Sampaloc Lake’s seasonal water quality patterns, as monsoon-driven changes are crucial to maintaining its ecological balance and sustainability.

Keywords: seasonal water quality dynamics, Philippine tropical lake, monsoon-driven conditions, stratification and mixing

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Authors: Michelle E. Taylor, Clare E. Morrall

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Microplastics are small particles produced for industrial purposes or formed by breakdown of anthropogenic debris. Caribbean nations import large quantities of plastic products. The Caribbean region is vulnerable to natural disasters and Climate Change is predicted to bring multiple additional challenges to island nations. Microplastics have been found in an array of marine environments and in a diversity of marine species. Occurrence of microplastic in the intestinal tracts of marine fish is a concern to human and ecosystem health as pollutants and pathogens can associate with plastics. Studies have shown that the incidence of microplastics in marine fish varies with species and location. Prevalence of microplastics (≤ 5 mm) in fish species from Grenadian waters (representing pelagic, semi-pelagic and demersal lifestyles) harvested for human consumption have been investigated via gut analysis. Harvested tissue was digested in 10% KOH and particles retained on a 0.177 mm sieve were examined. Microplastics identified have been classified according to type, colour and size. Over 97% of fish examined thus far (n=34) contained microplastics. Current and future work includes examining the invasive Lionfish (Pterois spp.) for microplastics, investigating marine invertebrate species as well as examining environmental sources of microplastics (i.e. rivers, coastal waters and sand). Owing to concerns of pollutant accumulation on microplastics and potential migration into organismal tissues, we plan to analyse fish tissue for mercury and other persistent pollutants. Despite having ~110,000 inhabitants, the island nation of Grenada imported approximately 33 million plastic bottles in 2013, of which it is estimated less than 5% were recycled. Over 30% of the imported bottles were ‘unmanaged’, and as such are potential litter/marine debris. A revised Litter Abatement Act passed into law in Grenada in 2015, but little enforcement of the law is evident to date. A local Non-governmental organization (NGO) ‘The Grenada Green Group’ (G3) is focused on reducing litter in Grenada through lobbying government to implement the revised act and running sessions in schools, community groups and on local media and social media to raise awareness of the problems associated with plastics. A local private company has indicated willingness to support an Anti-Litter Campaign in 2018 and local awareness of the need for a reduction of single use plastic use and litter seems to be high. The Government of Grenada have called for a Sustainable Waste Management Strategy and a ban on both Styrofoam and plastic grocery bags are among recommendations recently submitted. A Styrofoam ban will be in place at the St. George’s University campus from January 1st, 2018 and many local businesses have already voluntarily moved away from Styrofoam. Our findings underscore the importance of continuing investigations into microplastics in marine life; this will contribute to understanding the associated health risks. Furthermore, our findings support action to mitigate the volume of plastics entering the world’s oceans. We hope that Grenada’s future will involve a lot less plastic. This research was supported by the Caribbean Node of the Global Partnership on Marine Litter.

Keywords: Caribbean, microplastics, pollution, small island developing nation

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Authors: Amit Chaudhary, B. S. Yadav, P. K. Maurya, A. M., S. Srivastava, S. Singh, A. Mani

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Cold shock protein A (CspA) is major cold inducible protein present in Escherichia coli. The protein is involved in stabilizing secondary structure of RNA by working as chaperone during cold temperature. Two RNA binding motifs play key role in the stabilizing activity. This study aimed to investigate implications of low temperature on structure and RNA binding activity of E. coli CspA. Molecular dynamics simulations were performed to compare the stability of the protein at 37°C and 10 °C. The protein was mutated at RNA binding motifs and docked with RNA to assess the stability of both complexes. Results suggest that CspA as well as CspA-RNA complex is more stable at low temperature. It was also confirmed that RNP1 and RNP2 play key role in RNA binding.

Keywords: CspA, homology modelling, mutation, molecular dynamics simulation

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Authors: Schehrazad Selmane

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We present a deterministic model which describes the dynamics of tuberculosis in Algerian population where the vaccination program with BCG is in place since 1969 and where the WHO recommendations regarding the DOTS (directly observed treatment, short course) strategy are in application. The impact of an intervention program, targeting recently infected people among all close contacts of active cases and their treatment to prevent endogenous reactivation, on the incidence of tuberculosis, is investigated. We showed that a widespread treatment of latently infected individuals for some years is recommended to shift from higher to lower equilibrium state and thereafter relaxation is recommended.

Keywords: deterministic model, reproduction number, stability, tuberculosis

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Authors: Rada Somkhuean, Sa-aat Niwitpong, Suparat Niwitpong

Abstract:

This paper presents the generalized p-values for testing the difference between two future population means when the variances are unknown, in both cases for when the variances are equal and unequal. We also derive a closed form expression of the upper bound of the proposed generalized p-value.

Keywords: generalized p-value, two future population means, upper bound, variances

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Authors: J. D. Martínez-Vargas, C. Castro-Hoyos, G. Castellanos-Dominguez

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In this work, we propose a novel approach for measuring the stationarity level of a multichannel time-series. This measure is based on a stationarity definition over time-varying spectrum, and it is aimed to quantify the relation between local stationarity (single-channel) and global dynamic behavior (multichannel dynamics). To assess the proposed approach validity, we use a well known EEG-BCI database, that was constructed for separate between motor/imagery tasks. Thus, based on the statement that imagination of movements implies an increase on the EEG dynamics, we use as discriminant features the proposed measure computed over an estimation of the non-stationary components of input time-series. As measure of separability we use a t-student test, and the obtained results evidence that such measure is able to accurately detect the brain areas projected on the scalp where motor tasks are realized.

Keywords: stationary measure, entropy, sub-space projection, multichannel dynamics

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Authors: Kai-Wei Ji, Dung-Ying Lin

Abstract:

This study investigates the impact of transportation on housing prices in regions surrounding Taiwan's science parks. As these parks evolve into crucial economic and population growth centers, they attract an increasing number of residents and workers, significantly influencing local housing markets. This demographic shift raises important questions about the role of transportation in shaping real estate values. Our research examines four major science parks in Taiwan, providing a comparative analysis of how transportation conditions and population dynamics interact to affect housing price premiums. We employ an origin-destination (OD) matrix derived from pervasive traffic data to model travel patterns and their effects on real estate values. The methodology utilizes a bi-level framework: a genetic algorithm optimizes OD demand estimation at the upper level, while a user equilibrium (UE) model simulates traffic flow at the lower level. This approach enables a nuanced exploration of how population growth impacts transportation conditions and housing price premiums. By analyzing the interplay between travel costs based on OD demand estimation and housing prices, we offer valuable insights for urban planners and policymakers. These findings are crucial for informed decision-making in rapidly developing areas, where understanding the relationship between mobility and real estate values is essential for sustainable urban development.

Keywords: demand estimation, genetic algorithm, housing price, transportation

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Authors: Zal U’yun Wan Mahmood, Norfaizal Mohamed, Nita Salina Abu Bakar, Yii Mei Wo, Abdul Kadir Ishak, Mohamad Noh Sawon, Mohd Tarmizi Ishak, Khairul Nizam Razali

Abstract:

The study of thorium radiotracer bioaccumulation in the whole body tropical freshwater fish (Anabas testudeneus; climb pearch) was performed. The objective of this study was to evaluate the effect of different Th-232 activity concentration andradiological dose in Anabas testudeneus under the laboratory bioaccumulation condition. Anabas testudeneus adults were exposed to different waterborne Th-232 levels: 0 BqL-1 (control), 50 BqL-1, 100 BqL-1,150 BqL-1and 200 BqL-1for 30 days. Radionuclide concentration ratios between the whole body levels and water levels were calculated and; total dose rates and risk quotients using ERICA Assessment Tool were also estimated. The results showed the increase of waterborne Th-232 concentration corresponded to a progressive decrease of Th concentration ratio. Meanwhile, the total dose rate (internal and external) in the whole body of Anabas testudeneus less than the ERICA dose rate screening value of 10 µGyh-1 and the risk quotient less than one. Thus, the findings can be concluded that the radiological dose of Th-232 to Anabas testudeneus is a very low probability and the situation may be considered to be of negligible radiological concern.

Keywords: Anabas testudeneus, bioaccumulation, radiological dose, Th-232

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Authors: Yao Jie, Yeo Khoon Seng

Abstract:

In recent decades, flapping wing aerodynamics has attracted great interest. Understanding the physics of biological flyers such as birds and insects can help improve the performance of micro air vehicles. The present research focuses on the aerodynamics of insect-like flapping wing flight with the approach of numerical computation. Insect model of hawkmoth is adopted in the numerical study with rigid wing assumption currently. The numerical model integrates the computational fluid dynamics of the flow and active control of wing kinematics to achieve stable flight. The computation grid is a hybrid consisting of background Cartesian nodes and clouds of mesh-free grids around immersed boundaries. The generalized finite difference method is used in conjunction with single value decomposition (SVD-GFD) in computational fluid dynamics solver to study the dynamics of a free hovering hummingbird hawkmoth. The longitudinal dynamics of the hovering flight is governed by three control parameters, i.e., wing plane angle, mean positional angle and wing beating frequency. In present work, a PID controller works out the appropriate control parameters with the insect motion as input. The controller is adjusted to acquire desired maneuvering of the insect flight. The numerical scheme in present study is proven to be accurate and stable to simulate the flight of the hummingbird hawkmoth, which has relatively high Reynolds number. The PID controller is responsive to provide feedback to the wing kinematics during the hovering flight. The simulated hovering flight agrees well with the real insect flight. The present numerical study offers a promising route to investigate the free flight aerodynamics of insects, which could overcome some of the limitations of experiments.

Keywords: aerodynamics, flight control, computational fluid dynamics (CFD), flapping-wing flight

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Authors: Justina I. R. Udotong, Ofonime U. M. John

Abstract:

Toxicity of copper (Cu), lead (Pb) and iron (Fe) to Tilapia guinensis was carried out for 4 days with a view to determining their effects on the liver and muscle tissues. Tilapia guinensis samples of about 10 - 14cm length and 0.2 – 0.4kg weight each were obtained from University of Calabar fish ponds and acclimated for three (3) days before the experimental set up. Survivors after the 96-hr LC50 test period were selected from test solutions of the heavy metals for the histopathological studies. Histological preparations of liver and muscle tissues were randomly examined for histopathological lesions. Results of the histological examinations showed gross abnormalities in the liver tissues due to pathological and degenerative changes compared to liver and muscle tissues from control samples (tilapia fishes from aquaria without heavy metals). Extensive hepatocyte necrosis with chronic inflammatory changes was observed in the liver of fishes exposed to Cu solution. Similar but less damaging effects were observed in the liver of fishes exposed to Pb and Fe. The extent of lesion observed was therefore heavy metal-related. However, no pathologic changes occurred in the muscle tissues.

Keywords: degenerative changes, heavy metal, hepatocyte necrosis, histopathology, toxicity

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