Data depth for the uniform distribution

Given a set $X$ of $k$ points and a point $z$ in the $n$ -dimensional euclidean space, the Tukey depth of $z$ with respect to $X$ , is defined as $m/k$ , where $m$ is the minimum integer such that $z$ is not in the convex hull of some set of $k-m$ points of $X$ . If $z$ belongs to the closed region $B$ delimited by an ellipsoid, define the continuous depth of $z$ with respect to $B$ as the quotient $V(z)/\text{ Vol }(B)$ , where $V(z)$ is the minimum volume of the intersection of $B$ with the halfspaces defined by any hyperplane passing through $z$ , and $\text{ Vol }(B)$ is the volume of $B$ . We consider $z$ a random variable and prove that, if $z$ is uniformly distributed in $B$ , the continuous depth of $z$ with respect to $B$ has expected value $1/2^{n+1}$ . This result implies that if $z$ and $X$ are uniformly distributed in $B$ , the expected value of Tukey depth of $z$ with respect to $X$ converges to $1/2^{n+1}$ as the number of points $k$ goes to infinity. These findings have applications in ecology, namely within the niche theory, where it is useful to explore and characterize the distribution of points inside species niche.     

Analysis of welding fumes: A short note on the comparison between two sampling techniques

It is well established that welding fumes contain toxic substances, and that its composition is dependent on multiple factors, such as nature of the welding process and chemical compositions of the welding consumables and base materials. In order to prevent accidents and, thus to contribute to the safety of protection of welders, the establishment of a database on welding fume components is considered as essential. This has led to the development and upgradation of sampling techniques of welding fumes. Up to now, few standard techniques exist in this area. This study describes the results of the analysis of welding fumes, in terms of heavy metals, for a set of welding electrodes commonly used in carbon steel manufacture. Sampling was done by two different techniques: using the one currently known as “fume box” and common techniques in workplace atmospheres.     

Endocrine disruptors in the Leça River and nearby Porto Coast (NW Portugal): presence of estrogenic compounds and hypoxic conditions

The Leça River and two beaches close to the north and south margins of the estuary, nowadays an important seaport harbor, show signs of contamination. However, the chemical nature of that contamination is uncertain. Therefore, this study checked for the presence of 11 endocrine disrupting compounds (EDCs) of animal (17β-estradiol and estrone), pharmaceutical (17α-ethynylestradiol), and industrial (alkylphenols, alkylphenol ethoxylates, and bisphenol A) origins in water samples collected from six points at the river gradient and at two sites in the coastline (Atlantic Ocean). Along with the EDCs, evaluated by gas chromatography – mass spectroscopy (GC-MS) during spring, summer, and autumn, physico-chemical parameters were also assessed and particular attention was given to dissolved oxygen (DO) levels. Data showed the presence of high amounts of estrogens (up to 10?ng?L^?1 for estrone) and industrial compounds (up to 2?µg?L^?1 for the nonylphenol ethoxylates) at both river and seacoast. Along with this, clear signs of hypoxia were found in the river (DO??1 at several sampling sites). Taking into account these issues, it was concluded that there are local conditions for the occurrence of endocrine disruption in aquatic animals.     

Effects of environmental hypercapnia on hemato-immunological parameters,carbonic anhydrase,and Na+, K+-ATPase enzyme activities in rainbow trout (Oncorhynchus mykiss) tissues

In this study, the effects of environmental hypercapnia on hemato-immunological parameters and the activities of respiratory enzymes such as carbonic anhydrase (CA) and Na⁺, K⁺-ATPase were investigated in rainbow trout (Oncorhynchus mykiss) tissues (gill, liver and kidney). Batches of 12 fish were exposed to 4.5 mg L^?1 (control) and 14 mg L^?1 CO₂. No mortalities occurred during the 14 days of the experimental period. Red blood cell (RBC), hemoglobin (Hb), and hematocrit (Ht) levels, and innate immune parameters such as nitro blue tetrazolium (NBT), lysozyme, and myeloperoxidase activities, and the melano-macrophage frequency were negatively affected by elevated CO₂ levels. Patterns of change in CA activity differed among the gill, liver, and kidney. Compared with the activities of CA in the control group, the CA enzyme was significantly stimulated at day 7 in the gill tissue, whereas it was stimulated at day 14 of the experiment in the liver tissue of fish exposed to 14 mg L^?1 CO₂ (P < 0.05). In contrast to the pattern of CA enzyme activities, the Na⁺, K⁺-ATPase enzymes were stimulated significantly in the liver after day 7 but inhibited in the kidney and gill (P < 0.05). These results suggest that a subchronic exposure to hypercapnia of rainbow trout tissues may lead to adaptive changes in the respiratory enzymes and negatively affects hemato-immunological parameters.     

Seasonal variation of the concentrations of 137Cs in sediment,sea water,and some organisms collected from Izmir Bay and Didim

¹³⁷Cs in the marine environment mainly originates from fallout of atmospheric nuclear weapon tests, accidental releases from nuclear facilities, and from the Chernobyl accident. After the latter accident, many studies have been carried out in Turkey. The objective of this study is to assess the spatial distribution of ¹³⁷Cs in the coastal marine environment of the Aegean Sea.

The concentrations of ¹³⁷Cs in sediment, sea water, mussel (Mytilus galloprovincialis), and fish samples collected from the coast of the Aegean Sea at Izmir Bay and near Didim (Akbük) have been monitored for seasonal variability by the means of gamma spectroscopy: they vary between 0.10 ± 0.01 and 1.5 ± 0.3 Bq kg^?1, 1.3 ± 0.1 and 4.3 ± 0.4 Bq m^?3, <0.2 and 1.3 ± 0.3 Bq kg^?1, and 0.20 ± 0.03 and 1.8 ± 0.3 Bq kg^?1, respectively.     

Cloud point extraction of trace cyanide from environmental waters for indirect flame atomic absorption spectrometric determination

A method has been developed for indirect determination of cyanide in environmental waters based on cloud point extraction (CPE), preconcentration and determination by flame atomic absorption spectrometry (FAAS). The method was based on reduction of Cu(II) to Cu(I) in the presence of cyanide and complexation of the produced Cu(I)(CN)₂^? with gallocyanin (GC⁺) as an ion-pairing reagent at pH 4.0, followed by its extraction into polyethyleneglycol mono-p-nonylphenylether (Ponpe 7.5). Selectivity was improved with the use of suitable masking agents. Various factors influencing separation and preconcentration of cyanide have been investigated, and conditions were optimized, allowing determination of cyanide in the range of up to 1.2 mg L^?1 with a detection limit of 0.00045 mg L^?1. The method has been applied to the determination of cyanide in environmental waters, the results being in agreement with those obtained by a reference method.     

In vitro assessment of genotoxic and oxidative effects of zinc borate

Zinc borate is used as flame retardant for plastics and cellulose fibers, paper, rubber, and textiles. Despite its wide industrial use, there is limited information concerning its toxicity. The aim of the present study was to investigate the concentration dependence (0–280 mg L^?1) of its genotoxic activity on cultured human lymphocytes by using sister chromatid exchange and chromosomal aberration assays. Total antioxidant capacity and the extent of oxidative stress were also determined. Zinc borate was found to be non-genotoxic at all tested concentrations. It exhibited antioxidant activity at concentrations lower than 40 mg L^?1, and total oxidative stress levels were not changed at any applied concentration of zinc borate.     

Soil microbial diversity and C turnover modified by tillage and cropping in Laos tropical grassland

Agricultural practices should modify the diversity of soil microbes. However, the precise relationships between soil properties and microbial diversity are poorly known. Here, we study the effect of agricultural management on soil microbial diversity and C turnover in tropical grassland of north-eastern Laos. Three years after native grassland conversion into agricultural land, we compared soils from five land use management systems: one till versus two no-till rotational cropping systems, one no-till improved pasture and the natural grassland. Soils were incubated in microcosms during 64 days at optimum temperature and humidity. Bacterial and fungal diversity were evaluated by metagenomic 454-pyrosequencing of 16S and 18SrRNA genes, respectively. Changes in soil respiration patterns were evaluated by monitoring ¹²C- and ¹³C-CO₂ release after soil amendment with 13C-labelled wheat residues. Results show that residue mineralization increased with bacterial richness and diversity in the tilled treatment 7 days after soil amendment. Native soil organic C mineralization and priming effect increased with fungal richness and diversity in improved pasture and natural grassland. No-till cropping systems represented intermediate situations between tillage and pasture systems. Our findings evidence the potential of controlling soil microbial diversity by agricultural practices to improve soil biological properties. We suggest the promotion of no-till systems as a fair compromise between the need for agriculture intensification and soil ecological processes preservation.     

Porous media approach for RANS simulation of compound open-channel flows with submerged vegetated floodplains

Environmental Fluid Mechanics - The main goal of this study is the 3D numerical simulation of river flows with submerged vegetated floodplains. Since, vegetation layers are usually dense and...     

What affects perceptions of local residents toward protected areas? A case study from Kure Mountains National Park,Turkey

Local residents’ active participation is essential in protected areas to ensure achievement of conservation goals. One of the important steps for ensuring the active participation of local residents is to determine the perceptions and the factors that influence the perceptions of the local residents toward the protected area. In this context, the researchers of this study try to come up with the perception formed among the local residents toward the protected areas and especially toward Kure Mountains National Park (KMNP), the factors that would influence their perceptions and the ways how their perceptions are influenced. Multivariate linear regression was used to examine the putative influence of variables on perceptions toward protected areas. According to study results, the survey respondents have displayed a positive perception toward the protected areas in the world and in KMNP. It was determined that the respondents formed a positive perception from their economic, environmental and recreational interaction with KMNP. Also, the outcomes of this study showed that the perception developed by local residents toward the protected areas in the world and KMNP are influenced by gender, the level of satisfaction derived from the national park, duration of their residence in the national park, and that the perception that KMNP conservation are beneficial for the source values of the area, the current protection works in the world, as well as its impacts on their living conditions.