20 research outputs found
Hopf Bifurcation Analysis of Pathogen-Immune Interaction Dynamics With Delay Kernel
The aim of this paper is to study the steady states of the mathematical models with delay
kernels which describe pathogen-immune dynamics of infectious diseases. In the study of mathematical
models of infectious diseases it is important to predict whether the infection disappears
or the pathogens persist. The delay kernel is described by the memory function that reflects the
influence of the past density of pathogen in the blood and it is given by a nonnegative bounded and
normated function k defined on [ 0, ∞ ). By using the coefficient of the kernel k,
as a bifurcationparameter, the models are found to undergo a sequence of Hopf bifurcation.
The direction and the stability criteria of bifurcation periodic solutions are obtained by applying
the normal form theory and the center manifold theorems. Some numerical simulation examples for
justifying the theoretical results are also given
Environmental impact of mining activity in Bor area as indicated by the distribution of heavy metals and bacterial population dynamics in sediment
The environmental impact of inorganic pollution is pronounced in water adjacent
to Bor Copper Smelter Complex (RTB Bor, Serbia), with Cu, Zn, Pb, and As being
the main determinants of aquatic pollution pattern. Communities of
microorganisms present in the sediments are mainly affected by heavy metal
pollution. Some groups of bacteria can be considered pollution bio-indicators,
due to their sensibility and ability to bioaccumulate heavy metals, thus
contributing to reducing pollution. This study investigates the relationships
between trace element accumulation and heterogeneity in sediment bacteria
community structure found in water streams adjacent to the Bor Copper Smelter
Complex (RTB Bor, Serbia). Our results showed no contamination with copper,
zinc, nickel, iron, and chromium, but did show a low to moderate contamination
with lead and a moderate to high contamination with arsenic in aquatic sediments
within the area of interest. Spatial heterogeneity in sediment-associated
bacterial communities did not relate significantly to location of sampling
sites, except for iron reducing bacteria. Iron reducing bacteria and nitrifying
bacteria were the best distinguishing groups of bacteria. However, only iron
reducing bacteria were significantly influenced by sampling locations. The iron
reducing bacteria has correlated negatively with the degree of sediment
contamination with lead, and therefore, we suggest that this group of bacteria
could serve as potential bio-indicators of inorganic water contamination in Bor
RTB area
Environmental impact of mining activity in Bor area as indicated by the distribution of heavy metals and bacterial population dynamics in sediment
The environmental impact of inorganic pollution is pronounced in water adjacent
to Bor Copper Smelter Complex (RTB Bor, Serbia), with Cu, Zn, Pb, and As being
the main determinants of aquatic pollution pattern. Communities of
microorganisms present in the sediments are mainly affected by heavy metal
pollution. Some groups of bacteria can be considered pollution bio-indicators,
due to their sensibility and ability to bioaccumulate heavy metals, thus
contributing to reducing pollution. This study investigates the relationships
between trace element accumulation and heterogeneity in sediment bacteria
community structure found in water streams adjacent to the Bor Copper Smelter
Complex (RTB Bor, Serbia). Our results showed no contamination with copper,
zinc, nickel, iron, and chromium, but did show a low to moderate contamination
with lead and a moderate to high contamination with arsenic in aquatic sediments
within the area of interest. Spatial heterogeneity in sediment-associated
bacterial communities did not relate significantly to location of sampling
sites, except for iron reducing bacteria. Iron reducing bacteria and nitrifying
bacteria were the best distinguishing groups of bacteria. However, only iron
reducing bacteria were significantly influenced by sampling locations. The iron
reducing bacteria has correlated negatively with the degree of sediment
contamination with lead, and therefore, we suggest that this group of bacteria
could serve as potential bio-indicators of inorganic water contamination in Bor
RTB area
Environmental impact of mining activity in Bor area as indicated by the distribution of heavy metals and bacterial population dynamics in sediment
The environmental impact of inorganic pollution is pronounced in water adjacent
to Bor Copper Smelter Complex (RTB Bor, Serbia), with Cu, Zn, Pb, and As being
the main determinants of aquatic pollution pattern. Communities of
microorganisms present in the sediments are mainly affected by heavy metal
pollution. Some groups of bacteria can be considered pollution bio-indicators,
due to their sensibility and ability to bioaccumulate heavy metals, thus
contributing to reducing pollution. This study investigates the relationships
between trace element accumulation and heterogeneity in sediment bacteria
community structure found in water streams adjacent to the Bor Copper Smelter
Complex (RTB Bor, Serbia). Our results showed no contamination with copper,
zinc, nickel, iron, and chromium, but did show a low to moderate contamination
with lead and a moderate to high contamination with arsenic in aquatic sediments
within the area of interest. Spatial heterogeneity in sediment-associated
bacterial communities did not relate significantly to location of sampling
sites, except for iron reducing bacteria. Iron reducing bacteria and nitrifying
bacteria were the best distinguishing groups of bacteria. However, only iron
reducing bacteria were significantly influenced by sampling locations. The iron
reducing bacteria has correlated negatively with the degree of sediment
contamination with lead, and therefore, we suggest that this group of bacteria
could serve as potential bio-indicators of inorganic water contamination in Bor
RTB area