scholarly journals Spatio-temporal distribution patterns of Chironomidae communities in the wadis of Northern Tunisia

2022 ◽  
Vol 82 ◽  
Author(s):  
S. Boulaaba ◽  
S. Zrelli ◽  
A. Hedfi ◽  
M. Ben Ali ◽  
M. Boumaiza ◽  
...  
Keyword(s):  
Linear Models ◽  
Environmental Gradients ◽  
Abiotic Factors ◽  
Temporal Distribution ◽  
Thermal Conditions ◽  
Sodium Concentration ◽  
Dominant Group ◽  
Water Conductivity ◽  
Northern Tunisia ◽  
Spatio Temporal

Abstract In Northern Tunisia, seasonal streams, called wadi, are characterized by extreme hydrological and thermal conditions. These freshwater systems have very particular features as a result of their strong irregularity of flow due to limited precipitation runoff regime, leading to strong seasonal hydrologic fluctuations. The current study focused on the spatio-temporal distribution of chironomids in 28 sampling sites spread across the Northern Tunisia. By emplying PERMANOVA, the results indicated a significant spatio-temporal variation along various environmental gradients. The main abiotic factors responsible for noted differences in the spatial distribution of chironomids in wadi were the conductivity and temperature, closely followed by altitude, pH, salinity, talweg slope and dissolved oxygen, identified as such by employing distance-based linear models’ procedure. The Distance-based redundancy analysis ordination showed two main groups: the first clustered the Bizerte sites, which were characterized by high water conductivity, sodium concentration and salinity. The second main group comprised sites from the Tell zone and was characterized by low temperatures, neutral pH, low conductivity and nutrients content. The subfamily TANYPODIINAE (e.g., Prochladius sp., Prochladius choerus (Meigen, 1804) and Macropelopia sp.) was the dominant group at Tell zone, whereas species such as Diamesa starmachi (Kownacki et Kownacha, 1970) and Potthastia gaedii (Meigen, 1838) were found only in Tell Wadis. In contrast, chironomid species such as Diamesa starmachi (Kownacki et Kownacha, 1970), Potthastia gaedii (Meigen, 1838), Procladius choreus (Meigen, 1804) were specific for Tell Mountain. Cap Bon wadis region was dominated by genus Cladotanytarsus sp. The results of this survey liked the taxonomic composition of chironomid assemblages to the variation of hydromorphological and physic-chemical gradients across the northern Tunisia wadis.

scholarly journals Spatiotemporal mapping and detection of mortality cluster due to cardiovascular disease with Bayesian hierarchical framework using integrated nested Laplace approximation: A discussion of suitable statistic applications in Kersa, Oromia, Ethiopia

2018 ◽  
Vol 13 (2) ◽  
Author(s):  
Melkamu Dedefo ◽  
Henry Mwambi ◽  
Sileshi Fanta ◽  
Nega Assefa
Keyword(s):  
Cause Of Death ◽  
Linear Models ◽  
Temporal Distribution ◽  
Mortality Data ◽  
Contributing Factors ◽  
Bayesian Hierarchical ◽  
Hierarchical Framework ◽  
Temporal Models ◽  
Spatio Temporal ◽  
Non Parametric

Cardiovascular diseases (CVDs) are the leading cause of death globally and the number one cause of death globally. Over 75% of CVD deaths take place in low- and middle-income countries. Hence, comprehensive information about the spatio-temporal distribution of mortality due to cardio vascular disease is of interest. We fitted different spatio-temporal models within Bayesian hierarchical framework allowing different space-time interaction for mortality mapping with integrated nested Laplace approximations to analyze mortality data extracted from the health and demographic surveillance system in Kersa District in Hararege, Oromia Region, Ethiopia. The result indicates that non-parametric time trends models perform better than linear models. Among proposed models, one with non-parametric trend, type II interaction and second order random walk but without unstructured time effect was found to perform best according to our experience and. simulation study. An application based on real data revealed that, mortality due to CVD increased during the study period, while administrative regions in northern and south-eastern part of the study area showed a significantly elevated risk. The study highlighted distinct spatiotemporal clusters of mortality due to CVD within the study area. The study is a preliminary assessment step in prioritizing areas for further and more comprehensive research raising questions to be addressed by detailed investigation. Underlying contributing factors need to be identified and accurately quantified.

scholarly journals A Mathematical Study of the Influence of Hypoxia and Acidity on the Evolutionary Dynamics of Cancer

2021 ◽  
Vol 83 (7) ◽  
Author(s):  
Giada Fiandaca ◽  
Marcello Delitala ◽  
Tommaso Lorenzi
Keyword(s):  
Cancer Cells ◽  
Evolutionary Dynamics ◽  
Environmental Gradients ◽  
Abiotic Factors ◽  
Spatial Dynamics ◽  
Real Data ◽  
Tumour Cells ◽  
Environmental Stressors ◽  
Theoretical Understanding ◽  
Spatio Temporal

AbstractHypoxia and acidity act as environmental stressors promoting selection for cancer cells with a more aggressive phenotype. As a result, a deeper theoretical understanding of the spatio-temporal processes that drive the adaptation of tumour cells to hypoxic and acidic microenvironments may open up new avenues of research in oncology and cancer treatment. We present a mathematical model to study the influence of hypoxia and acidity on the evolutionary dynamics of cancer cells in vascularised tumours. The model is formulated as a system of partial integro-differential equations that describe the phenotypic evolution of cancer cells in response to dynamic variations in the spatial distribution of three abiotic factors that are key players in tumour metabolism: oxygen, glucose and lactate. The results of numerical simulations of a calibrated version of the model based on real data recapitulate the eco-evolutionary spatial dynamics of tumour cells and their adaptation to hypoxic and acidic microenvironments. Moreover, such results demonstrate how nonlinear interactions between tumour cells and abiotic factors can lead to the formation of environmental gradients which select for cells with phenotypic characteristics that vary with distance from intra-tumour blood vessels, thus promoting the emergence of intra-tumour phenotypic heterogeneity. Finally, our theoretical findings reconcile the conclusions of earlier studies by showing that the order in which resistance to hypoxia and resistance to acidity arise in tumours depend on the ways in which oxygen and lactate act as environmental stressors in the evolutionary dynamics of cancer cells.

Influence of temperature on the occurrence and distribution of the sand shrimp Crangon septemspinosaSay, 1818 (Decapoda: Caridea: Crangonidae) in polyhaline lagoons in Maryland, USA

2019 ◽  
Vol 39 (5) ◽  
pp. 586-593
Author(s):  
Paulinus Chigbu ◽  
Lauren Malinis ◽  
Hector Malagon ◽  
Steve Doctor
Keyword(s):  
Dissolved Oxygen ◽  
Relative Abundance ◽  
Linear Models ◽  
Abiotic Factors ◽  
Temporal Variations ◽  
Mean Temperature ◽  
Early Fall ◽  
Spatio Temporal ◽  
Maryland Coastal Bays ◽  
Chincoteague Bay

Abstract Sand shrimp, Crangon septemspinosaSay, 1818, is one of the most abundant decapod crustaceans in estuaries and coastal waters of the northwestern Atlantic Ocean, though little is known about its population dynamics in polyhaline lagoons of the mid-Atlantic region. Seasonal and spatial patterns of abundance and distribution of C. septemspinosa were evaluated in relation to temperature, salinity, and dissolved oxygen in Maryland coastal bays (MCBs) using monthly data (April to October 1994 to 2012). We tested the hypothesis that temperature influences the occurrence and distribution of sand shrimp in the lagoons. A consistent pattern of high relative abundance of shrimp in spring and its scarcity in summer and early fall was observed. Shrimp abundance was highest in the northern bays and at sites closest to the Ocean City Inlet during April, but lowest at sites in the upper parts of Chincoteague Bay and MCBs tributaries. As mean temperature increased from April (12.2–17.1 oC) to June (21.8–26.7 oC), the relative abundance of the shrimp decreased substantially at most sites except at two sites where mean water temperature was comparatively low (21.8–23.3 oC). By July, when mean temperature was at its maximum (23.1–28.9 oC) in the bays, shrimp were rarely caught in trawls even in early fall in spite of the decline in temperature. It is likely that shrimp moved into nearshore waters with cooler temperature or suffered high mortality due to high temperature during this period. Generalized linear models suggest that temperature, and temperature and dissolved oxygen combined, were the most important abiotic factors examined that influenced the spatial distribution of C. septemspinosa in May and June, respectively. Considering their trophic importance, the spatio-temporal variations in the occurrence and abundance of the shrimp have implications for food web dynamics in the MCBs.

scholarly journals Spatio-Temporal Distribution of Carabids Influenced by Small-Scale Admixture of Oak Trees in Pine Stands

Diversity ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 398
Author(s):  
Alexandra Wehnert ◽  
Sven Wagner ◽  
Franka Huth
Keyword(s):  
Linear Models ◽  
Interspecific Interactions ◽  
Temporal Distribution ◽  
Quercus Petraea ◽  
Small Scale ◽  
Spatial Effects ◽  
Oak Trees ◽  
Geostatistical Models ◽  
Temporal And Spatial ◽  
Spatio Temporal

In a region with poor soil fertility, low annual precipitation and large areas of homogenous Pinus sylvestris L. forests, conservation of old sessile oak (Quercus petraea (Matt.) Liebl.) trees is one option to enrich structure and species richness. We studied the affinities of Carabus coriaceus, C. violaceus, C. hortensis and C. arvensis for specific tree species and the resultant intra- and interspecific interactions. We focused on their temporal and spatial distributions. Pitfall traps were used as a surface-related capture method on a grid over an area of three hectares. Generalised linear models and generalised linear geostatistical models were used to analyse carabid activity densities related to distance-dependent spatial effects corresponding to tree zones (oak, oak–pine, pine). The results demonstrated significant spatial affinities among these carabids, especially for females and during the period of highest activity. Individuals of C. coriaceus showed a tendency to the oak zone and C. hortensis exhibited a significant affinity to the oak–pine mixture. Imagines of C. arvensis and C. violaceus were more closely related to pine. The observed temporal and spatial coexistence of the different Carabus species reveals that single admixed old oak trees can support greater diversity within pine-dominated forests.

ASSESSMENT OF THE FEATURES OF EXTREME LOW TEMPERATURES OF THE SURFACE AIR LAYER IN THE LAKE SEVAN BASIN (ARMENIA)

2020 ◽  
Vol 3 (1) ◽  
pp. 52-64
Author(s):  
V.J. MARGARYAN ◽  
Keyword(s):  
Low Temperatures ◽  
Temporal Distribution ◽  
Thermal Conditions ◽  
Absolute Minimum ◽  
Lake Sevan ◽  
Air Temperatures ◽  
Daily Data ◽  
The Absolute ◽  
Spatio Temporal ◽  
Surface Air Layer

The study is aimed to assess the patterns of spatio-temporal distribution of the extreme low temperatures of the Lake Sevan basin, their impact on the surrounding natural landscape landscape. As the source material, observations of daily data on the extremes of the minimum temperatures of the surface air layer at seven meteorological stations of the basin for the entire period (1891-2018). The methods used are mathematical-statistical, extrapolation, analytic, correlation, cartographic. A correlation was obtained between the average annual and annual absolute minimum values, as well as between the annual absolute minimum temperatures and the height of the area above sea level. The obtained relationships can be used to assess the thermal conditions of unexplored or little studied territories. As a result, a map of the spatial distribution of the annual absolute minimum temperatures of the surface air layer in the lake Sevan basin was compiled. Main conclusions. An analysis of the trend lines of temporary changes in the absolute minimum air temperatures shows that, at all weather stations currently operating in the basin, the absolute minimum temperatures tend to increase both monthly and annual...

Influence of Planting Density on Root Spatio-Temporal Distribution of Different Types of Maize under High-Yielding Cultivation Conditions

2013 ◽  
Vol 38 (7) ◽  
pp. 1286-1294 ◽  
Author(s):  
Zong-Xin LI ◽  
Yuan-Quan CHEN ◽  
Qing-Cheng WANG ◽  
Kai-Chang LIU ◽  
Wang-Sheng GAO ◽  
...  
Keyword(s):  
Temporal Distribution ◽  
Planting Density ◽  
Cultivation Conditions ◽  
Different Types ◽  
Spatio Temporal
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