Journal of Mathematical and Fundamental Sciences
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Properties of the Environment of Galaxies in Clusters of Galaxies CL 0024+1654 and RX J0152.7−1357
Full text linkWe report the results of combined analyses of X-ray and optical data of two galaxy clusters, CL 0024+1654 and RX J0152.7−1357 at redshift z = 0.395 and z = 0.830, respectively, offering a holistic physical description of the two clusters. Our X-ray analysis yielded temperature and density profiles of the gas in the intra-cluster medium (ICM). Using optical photometric and spectroscopic data, complemented with mass distribution from a gravitational lensing study, we investigated any possible correlation between the physical properties of the galaxy members, i.e. their color, morphology, and star formation rate (SFR), and their environments. We quantified the properties of the environment around each galaxy by galaxy number density, ICM temperature, and mass density. Although our results show that the two clusters exhibit a weaker correlation compared to relaxed clusters, it still confirms the significant effect of the ICM on the SFR in the galaxies. The close relation between the physical properties of galaxies and the condition of their immediate environment found in this work indicates the locality of galaxy evolution, even within a larger bound system such as a cluster. Various physical mechanisms are suggested to explain the relation between the properties of galaxies and their environment
Some Remarks on Results Related to ∇-Convex Function
Full text linkIn the present article, we give new techniques for proving general identities of the Popoviciu type for discrete cases of sums for two dimensions using higher-order ∇-divided difference. Also, integral cases are deduced by different methods for differentiable functions of higher-order for two variables. These identities are a generalization of various previously established results. An application for the mean value theorem is also presented
Antifungal Activity of Endophytic Bacteria Associated with Sweet Sorghum (Sorghum bicolor)
Full text linkThe contribution of endophytic bacteria to the wellbeing of plants as biocontrol agents may be due to endophytic bacteria growing in the same niche as phytopathogens. This work was conducted to study the antagonistic activity of endophytic bacteria recovered from sweet sorghum against Sclerotium rolfsii, Fusarium solani, Fusarium oxysporum, Colletotrichum gloeosporioides in vitro and evaluate the mechanisms of these fungal inhibitions. We selected 78 endophytic bacteria from the stem and root of sweet sorghum plants. They were tested for antagonist activity by direct confrontation method. Antifungal compound production and lytic enzyme activity were examined to determine their mechanisms in inhibiting fungal pathogens. Antifungal compound production was checked by detecting the presence of NRPS and PKS genes. Lytic enzyme activity of the bacteria was evaluated by their ability to produce cellulase, chitinase, and protease. Selected bacteria were identified using molecular analysis based on the 16S rRNA gene. 14 out of the 78 tested isolates showed antagonistic activity and two were able to inhibit all four tested fungal strains. Four bacteria, designated as ACIL1, ACNM4, ACNM6, and ATNM4, produced natural products via NRPS pathway, but only one bacterial extract, designated as ACNM4, showed fungal inhibition. Ten isolates were able to produce hydrolytic enzymes. Endophytic bacteria identified as Burkholderia were revealed to have potential as a biocontrol agent
Chemical Constituents of Indonesian Micromelum minutum Leaves and Their Cytotoxicity Against MCF-7 and 4T1 Breast Cancer Cells
Full text linkMicromelum minutum is used widely in traditional folk medicine. Although this species has been investigated extensively and several bioactive compounds have been isolated, little work has been done on Indonesian M. minutum. This research aimed to study the chemical constituents and biological activities of M. minutum cultivated in Bantimurung Bulusaraung National Park, South Sulawesi, Indonesia. The isolated compounds were assessed for their cytotoxicity towards MCF-7 and 4T1 cell lines by MTT method. The dried ground leaves of M. minutum were sequentially macerated with n-hexane, ethyl acetate, and methanol. The n-hexane and ethyl acetate extracts contained a flavonoid 5,7-dihydroxy-3,4',8-trimethoxyflavone (1) which inhibited MCF-7 and 4T1 cell viability by 50% at concentrations of 369±8 and 227±5 µM, respectively. Further separation of the ethyl acetate extract by column chromatography yielded acetyldihydromicromelin A (2) and a mixture of dihydromicromelin A (3) and dihydromicromelin B (4), which were not active toward MCF-7 and 4T1 cells
Graphs of Neighborhood Metric Dimension Two
Full text linkA subset of vertices of a simple connected graph is a neighborhood set (n-set) of G if G is the union of subgraphs of G induced by the closed neighbors of elements in S. Further, a set S is a resolving set of G if for each pair of distinct vertices x,y of G, there is a vertex s∈ S such that d(s,x)≠d(s,y). An n-set that serves as a resolving set for G is called an nr-set of G. The nr-set with least cardinality is called an nr-metric basis of G and its cardinality is called the neighborhood metric dimension of graph G. In this paper, we characterize graphs of neighborhood metric dimension two
Indonesian Micromelum minutum Leave Extracts and Their Cytotoxic Activities toward Breast Cancer Cell Lines
Full text linkIsolation and identification of compounds and pharmacological activity of the Micromelum minutum grown in some countries has been done, but the Indonesian M. minutum has not been studied, either phytochemically or pharmacologically. This study aimed to determine the cytotoxic activity of Indonesian M. minutum leave extracts toward MCF-7 and 4T1 breast cancer cell lines. The leaves were obtained from M. minutum grow in Bantimurung National Park, Bulusaraung, South Sulawesi, and then were macerated gradually in hexane, ethyl acetate, and methanol. The cytotoxic activity of obtained extracts was determined by MTT assay. The extraction yielded hexane (HEM), ethyl acetate (EEM), and methanol (MEM) extracts of 2.65, 6.12, and 6.49%, respectively. HEM was the most potent extract with IC50 values of 148 and 87 µg/mL on MCF-7 and 4T1 cells, respectively, followed by EEM (185 and 170 µg/mL). MEM possessed a weak potency with an IC50 value of 384 µg/mL on MCF-7 cells and was not toxic toward 4T1 cells. Therefore, HEM is important to be further investigated for its active constituents
Basin-scale Paleoecology: Using Semi-quantitative Analysis of the Ichnofabric within Kutai Basin (Indonesia)
Full text linkIchnofossils are still not used in paleoecological studies, even though they are a valuable proxy for paleoecology. This study focused on a semi-quantitative approach to a number of ichnofabric variables, i.e. ichnofossil association, bioturbation index (BI), ichnodiversity (ID), number of behaviors (NB), penetration depth (PD), and burrow diameter (DM). It was proved that the scores of those variables were low to medium because of the paleoecological fluvial-marine transition depositional processes in the Serravallian-Tortonian interval in Kutai Basin, Indonesia. This paper contributes an ichnofabric model that is visualized as histograms. One histogram shows the most common ichnofossil associations found in ichnofabric units, i.e., Ophiomorpha, Skolithos, Paleophycus, Planolites, Thalassinoides, and Chondrites. The other histograms describe the ichnofabric variables scores for BI, ID, NB, PD, and DM. The variables represent low to medium scores, a characteristic of a brackish paleoecology at basin-scale, a unique indicator for the fluvial-marine transition depositional system
Optimal Control in a Mathematical Model of Smoking
Full text linkThis paper presents a dynamic model of smoking with optimal control. The mathematical model is divided into 5 sub-classes, namely, non-smokers, occasional smokers, active smokers, individuals who have temporarily stopped smoking, and individuals who have stopped smoking permanently. Four optimal controls, i.e., anti-smoking education campaign, anti-smoking gum, anti-nicotine drug, and government prohibition of smoking in public spaces are considered in the model. The existence of the controls is also presented. The Pontryagin maximum principle (PMP) was used to solve the optimal control problem. The fourth-order Runge-Kutta was employed to gain the numerical solutions
Modeling the Phenomenon of Xenophobia in Africa
Full text linkIn this study, we applied the principle of a competitive predator-prey system to propose a prey-predator-like model of xenophobia in Africa. The boundedness of the solution, the existence and stability of equilibrium states of the xenophobic model are discussed accordingly. As a special case, the coexistence state was found to be locally and globally stable based on the parametric conditions of effective group defense and anti-xenophobic policy implementation. The system was further analyzed by Sotomayor’s theory to show that each equilibrium point bifurcates transcritically. However, numerical proof showed period-doubling bifurcation, which makes the xenophobic situation more chaotic in Africa. Further numerical simulations support the analytical results with the view that tolerance, group defense and anti-xenophobic policies are critical parameters for the coexistence of foreigners and xenophobes
A New Family of Exponential Type Estimators in the Presence of Non-Response
Full text linkWe propose families of estimators for the population mean using an exponential function in case of non-response. This situation is examined under two cases, Case I and II. The bias, MSE and minimum MSE are separately obtained for both cases. We compare the proposed estimators theoretically with the main estimators from the literature, such as Hansen and Hurwitz (1946), ratio, regression and exponential estimators. The conditions for which the proposed estimators are most efficient are obtained. Moreover, different empirical studies are conducted to support the theoretical results for both cases