Determination of cadmium and lead in human milk

The objectives of this study were to determine cadmium and lead concentrations in the breast milk of healthy lactating women who were living in Zarrinshahr, an industrial area of Iran and to investigate the effect of mother’s age, parity and smoking habits in families living in the vicinity of areas contaminated with heavy metals. Cadmium and lead concentrations were determined by graphite furnace atomic absorption spectrometry in 44 milk samples from healthy lactating women collected on first to sixth postpartum week. Accuracy of the analysis was checked by various methods including the use of reference material. The mean ± standard deviation of cadmium and lead concentrations in human milk were 2.44 ± 1.47 μg/L (range 0.62–6.32 μg/L) and 10.39 ± 4.72 μg/L (range 3.18–24.67 μg/L), respectively. There was a positive correlation between the concentrations of lead in milk samples and mother’s age and parity (P < 0.05). Also the concentration of cadmium in breast milk significantly increased (P < 0.05) in mothers who were actively and/or passively exposed to smoking. The results of this study showed that lead and cadmium concentrations in milk samples from lactating women in Zarrinshahr were high. This can be a major public health hazard for the inhabitants living in this industrial region of Iran.     

Numerical simulation of a possible origin of the positive radial metallicity gradient of the thick disk

We analyze the radial and vertical metallicity and [α/Fe] gradients of the disk stars of a disk galaxy simulated in a fully cosmological setting with the chemodynamical galaxy evolution code GCD+. We study how the radial abundance gradients vary as a function of height above the plane and find that the metallicity([α/Fe]) gradient becomes more positive(negative) with increasing height, changing sign around1.5 kpc above the plane. At the largest vertical height(2 |z| 3 kpc), our simulated galaxy shows a positive radial metallicity gradient. We find that the positive metallicity gradient is caused by the age-metallicity and age-velocity dispersion relation, where younger stars have higher metallicity and lower velocity dispersion. Due to the agevelocity dispersion relation, a greater fraction of younger stars reaches |z| 2 kpc at the outer region, because of the lower gravitational restoring force of the disk, i.e.flaring. As a result, the fraction of younger stars with higher metallicity due to the age-metallicity relation becomes higher at the outer radii, which makes the median metallicity higher at the outer radii. Combining this result with the recently observed age-metallicity and age-velocity dispersion relation for the Milky Way thick disk stars suggested by Haywood et al., we argue that the observed(small) positive radial metallicity gradient at large heights of the Milky Way disk stars can be explained by flaring of the younger thick and/or thin disk stars.     

Counterfactual reasoning in space and time: Integrating graphical causal models in computational movement analysis

Movement analysis is distinguished by an emphasis on understanding via observation and association. However, an important component of movement from the human and computer modeling perspective is the processes that bring about movement behavior in the first place. This article contextualizes the graphical causal modeling framework (for association, intervention, and counterfactual causal analysis) in GIScience, and more specifically within movement analysis studies. This is done by modeling the movement behavior of football players, applied to spatiotemporal data generated by an agent-based simulation. The movement dataset is thoroughly analyzed to infer the statistical associations among its variables, to estimate the effect of an intervention on some of those variables, and to answer a few counterfactual questions from the observations. We conclude that causal graphs (i.e., directed acyclic graphs), if implemented correctly, can assist analysts in infering causal relations from movement data. This research suggests the integration of causal graphs and agent-based paradigms as one solution for computational movement analysis.     

Rainfall–runoff modelling and water balance analysis for Al-Hindiyah barrage,Iraq using remote sensing and GIS

Investigation of rainfall–run-off modelling is an important subject to develop any available means to water supply, which maintains human life such as run-off harvesting method. This study aims to analyse and understand the rainfall–run-off relationship in a part of Babil city, Iraq. Curve number which is a function of land use, soil texture, soil moisture and land slope is used in this study. Remote sensing and GIS are used to analyse the data and to produce the run-off depth map for the study area. Then, the run-off depth is used with rainfall to investigate the relationship between them using linear correlation. This study showed a strong linear relationship between rainfall and run-off (R² = 0.992). It indicates that in the absence of rainfall data, run-off data can be used to estimate rainfall amount. Also, the study revealed through water balance analysis that there is an average monthly change in storage.     

Monitoring of 45 pesticides in Lebanese surface water using Polar Organic Chemical Integrative Sampler (POCIS)

The aim of this study is to assess the dissolved concentration of 45 pesticides in the surface waters of the Lebanese Republic using Polar Organic Chemical Integrative Sampler "POCIS". All of the sampling sites are located in the major agricultural land areas in Lebanon. POCIS (n = 3) were deployed at Ibrahim River, Qaraoun Lake and Hasbani River for a duration of 14 days. The total concentration of pesticides ranged from not detected (nd) to 137.66 ng.L^-1. Chlorpyrifos, DDE-pp, diazinon and Fenpropathrin were the most abundant compounds. Qaraoun Lake and Hasbani River were found to be more polluted than Ibrahim River, since they receive large amounts of waste water derived from nearby agricultural lands and they had the lowest dilution factor. The aqueous average concentration of the target compounds were estimated using sampling rates obtained from the literature. Comparison between Time Weighed Average concentrations "TWA" using POCIS and spot sampling is presented. Results showed that POCIS TWA concentrations are in agreement with spot sampling concentrations for Ibrahim and Hasbani Rivers. The toxicity of the major detected pesticides on three representative aquatic species (Daphnia magna, Scenedesmus quadricauda and Oncorhynchus mykiss) is also reported.     

Collapse assessment of steel moment frames using endurance time method

In endurance time(ET) method structures are subjected to a set of predesigned intensifying excitations. These excitations are produced in a way that their response spectrum, while complying with a specifi ed spectrum, intensifi es with time so they can be used approximately to simulate the average effects of several ground motions scaled to different intensities. In this paper applicability of the ET method for evaluating collapse potential of buildings is investigated. A set of four steel moment frames is used for collapse assessment. The process of using ET method in collapse evaluation is explained and the results are compared with incremental dynamic analysis(IDA) results. It is shown that although the computational effort using the ET method is much less than the IDA analysis, the results of both methods are consistent. Finally collapse fragility curves using ET and IDA methods are produced and it is shown that the probabilities of collapse in different hazard levels are also consistent.     

Long-term periodic drought modeling

Drought modeling is essential to water resources management and planning. In this study, Fourier spectral analysis is used to examine the cyclic structure for drought patterns and develop a long-term periodic model. A case study for historical precipitation data, obtained from the arid region of Kuwait for the period spanning from January 1967 to December 2009, are converted to drought measurements following the Standardized Precipitation Index (SPI) criterion. The SPI calculations are performed for two time scales of 12 and 24 months. The periodogram technique used for both time scales reveals periodicities of 12, 14, 19, 26, 31, 43, 64, 103 and 258 months. It is advocated here that the 26- and 258-month periods present in the data are attributed, respectively, to a Quasi-Biennial Oscillation pattern and a solar cycle over which the magnetic polarity of the sun first reverses then reverts to its former state. The detected periods are manipulated in the SPI model to produce drought forecasts, which suggest that until the end of year 2024 the climate is considered normal to very wet. This finding may be implemented to assess policy requirements related to water resources management.     

Investigation on the Characteristics of Pore Water Flow During CRS Consolidation Test

Several experimental methods have been proposed for consolidation test such as: constant loading rate, constant gradient and constant rate of strain (CRS). Unfortunately, there are no unique criteria for performing the CRS consolidation test. Also, there are considerable differences among the standards proposed for the test. In the present paper, authors have tried to find the reasons for differences among standards, by studying the basic assumptions made on the characteristics of the pore water flow during consolidation process. In the course of study, CRS consolidation tests were carried out under different strain rates on remolded samples. The results of the tests have indicated that the Darcy’s law is not valid throughout the CRS test and therefore, any consolidation equation based on Darcy’s law would not provide accurate results. The results of the current experiments also showed that with regard to the applied strain rates, there are three different flow regimes governing the process named as: pre-linear (non-Darcy flow), linear (Darcy flow) and post-linear (non-Darcy flow). Experimental results also showed that distinction between boundaries of linear and nonlinear flow is possible from the excess pore pressure developed during the tests.