STAMP-based analysis on the railway accident and accident spreading: Taking the China–Jiaoji railway accident for example

Each hazard analysis technique is based on a model of accident causation. Most accident models regard accidents as resulting from a chain or sequence of events, such models are fit for accidents caused by failures of physical components and for relatively simple systems, but suffer from serious deficiencies when they are applied to software-intensive, complex engineering systems. Recently, a new accident model called System-Theoretic Accident Models and Process (STAMP) for system safety has been proposed, it is based on control theory and enforces constraints on hazards and thereby prevent accidents. In this paper, taking the China–Jiaoji railway accident happened on April 28, 2008 as an example, the STAMP approach has been used to analyze the railway accident and some improvement measures have been proposed. As the occurrence of one accident can cause many other accidents happen, based on the STAMP-based analysis, the accident spreading processes have also been discussed and modeled, which will be helpful to analyze accidents spreading in a broad sense and establish effective emergent measures for accident response management.     

Low-cost automated rain collector and its application to the study of wet only deposition in São Paulo (Brazil)

An automatic rain collector was developed with emphasis on simplicity, construction with readily available low-cost materials, inexpensive maintenance and reliable operation at temperatures above freezing point. The rain sensor is of the heated AC conductometric type and the circuit includes electronic protections against false triggering by electrical transients. With this collector, the first studies of chemical characterization of wet only deposition were made in São Paulo over the period of November 1988 to June 1990. Results are presented and compared with previous total deposition studies. For this period the volume-weighted mean values of the pH and conductivity were 4.6 and 19 μS cm⁻¹, respectively.     

Function Approximation and Documentation of Sampling Data Using Artificial Neural Networks

Biodiversity studies in ecology often begin with the fitting and documentation of sampling data. This study is conducted to make function approximation on sampling data and to document the sampling information using artificial neural network algorithms, based on the invertebrate data sampled in the irrigated rice field.Three types of sampling data, i.e., the curve species richness vs. the sample size, the curve rarefaction, and the curve mean abundance of newly sampled species vs.the sample size, are fitted and documented using BP (Backpropagation) network and RBF (Radial Basis Function) network. As the comparisons, The Arrhenius model, and rarefaction model, and power function are tested for their ability to fit these data. The results show that the BP network and RBF network fit the data better than these models with smaller errors.BP network and RBF network can fit non-linear functions (sampling data) with specified accuracy and don't require mathematical assumptions. In addition to the interpolation, BP network is used to extrapolate the functions and the asymptote of the sampling data can be drawn. BP network cost a longer time to train the network and the results are always less stable compared to the RBF network. RBF network require more neurons to fit functions and generally it may not be used to extrapolate the functions. The mathematical function for sampling data can be exactly fitted using artificial neural network algorithms by adjusting the desired accuracy and maximum iterations. The total numbers of functional species of invertebrates in the tropical irrigated rice field are extrapolated as 140 to 149 using trained BP network, which are similar to the observed richness.     

Forest succession suppressed by an introduced plant-fungal symbiosis

Microbial symbionts can affect plant nutrition, defensive chemistry, and biodiversity. Here we test the hypothesis that symbionts alter the speed and direction of plant succession in communities that are shifting from grasslands to forests. A widespread C3 grass introduced to the United States, Lolium arundinaceum (tall fescue), hosts a fungal endophyte that is toxic to herbivores. In replicated experimental grasslands, the presence of the endophyte in tall fescue reduced tree abundance and size, altered tree composition, and slowed plant species turnover. In addition, consumption of tree seedlings by voles (Microtus spp.) was 65% higher in plots with the endophyte at the one grassland site where these data were collected. Despite its negligible contribution to community biomass, a microbial symbiont suppressed tree establishment, posing an important constraint on the natural transition from grasslands to forests.     

Why are larvae of the social parasite wasp <Emphasis Type="Italic">Polistes sulcifer</Emphasis> not removed from the host nest?

A challenge for parasites is how to evade the sophisticated detection and rejection abilities of potential hosts. Many studies have shown how insect social parasites overcome host recognition systems and successfully enter host colonies. However, once a social parasite has successfully usurped an alien nest, its brood still face the challenge of avoiding host recognition. How immature stages of parasites fool the hosts has been little studied in social insects, though this has been deeply investigated in birds. We look at how larvae of the paper wasp obligate social parasite Polistes sulcifer fool their hosts. We focus on cuticular hydrocarbons (CHCs), which are keys for adult recognition, and use behavioral recognition assays. Parasite larvae might camouflage themselves either by underproducing CHCs (odorless hypothesis) or by acquiring a chemical profile that matches that of their hosts. GC/MS analyses show that parasite larvae do not have lower levels of CHCs and that their CHCs profile is similar to the host larval profile but shows a reduced colony specificity. Behavioral tests show that the hosts discriminate against alien conspecific larvae from different colonies but are more tolerant towards parasite larvae. Our results demonstrate that parasite larvae have evolved a host larval profile, which overcomes the host colony recognition system probably because of the lower proportion of branched compounds compared to host larvae. In some ways, this is a similar hypothesis to the odorless hypothesis, but it assumes that the parasite larvae are covered by a chemical blend that is not meaningful to the host.     

Umbilical cord blood PBDEs concentrations are associated with placental DNA methylation

BackgroundIn utero polybrominated diphenyl ethers (PBDEs) exposure has been associated with adverse fetal growth. Alterations in placental DNA methylation might mediate those adverse effects.ObjectivesTo examine the associations between in utero PBDEs exposure and DNA methylation in human placenta.MethodsEighty apparently healthy mother-newborn pairs delivering at the Second Affiliated Hospital of Wenzhou Medical College were enrolled in this study. Placental DNA methylation of LINE1, NR3C1 and IGF2 was measured by quantitative polymerase chain reaction-pyrosequencing. In utero PBDEs exposure was assessed by measuring umbilical cord blood PBDEs concentrations.ResultsFor LINE-1, higher levels of BDE-66 exposure were associated with decreased DNA methylation (β = − 0.9, 95% CI, − 1.8 to − 0.1); For NR3C1, BDE-153 concentrations was significantly inversely associated with DNA methylation (β = − 2.0, 95% CI, − 3.7 to − 0.2); For IGF2, elevated concentrations of both BDE-153 (β = − 1.7; 95% CI, − 3.0 to − 0.4) and BDE-209 (β = − 1.0; 95% CI, − 1. 9 to − 0.1) were significantly associated with decreased DNA methylation.ConclusionsWe found that placental DNA methylation is associated with in utero PBDEs exposure. Changes in placental DNA methylation might be part of the underlying biological pathway between in utero PBDEs exposure and adverse fetal growth.     

Farming adaptation to environmental change in coastal Bangladesh: shrimp culture versus crop diversification

Farming in coastal Bangladesh includes rice/shrimp and rice/non-rice cropping systems. The former has been highly profitable but has exacerbated salinization of soil and water. We evaluate the relative profitability, riskiness, and sustainability of the two cropping systems, using data from two coastal villages in Khulna District. Shrimp cultivation was initially very rewarding. However, over 12–15 years, the cropping system experienced declining profitability, increased salinity, and adverse impacts on rice cropping and the local environment. From 2009, farmers adapted the system by changing the pond (gher) infrastructure, adopting delayed planting of a saline-tolerant rice cultivar, flushing out accumulated salt with freshwater during rice cropping, and allowing the soil to dry out after harvesting rice. The budgeting results show that with current management practices, the rice/shrimp system is economically more viable (higher returns to land and labour and less risky) than the rice/non-rice system. Soil analyses showed that while salinity was higher in the gher during the dry season, it was significantly reduced in the wet season and was very similar between the two systems (1–2 dS/m). Hence, as well as being more profitable and less risky, the rice/shrimp system may well be more sustainable than previously observed.     

Loss of carbofuran from rice paddy water: Chemical and physical factors

Abstract

The loss of carbofuran was studied from rice paddy water treated with a granular formulation of the insecticide, and from ponds filled with drainage from the paddy. The average half‐life (t_1/2) for carbofuran loss was 57 hr. Controlled experiments indicated that pH was the predominating factor governing carbofuran loss from water in the environment studied. The loss due to hydrolysis was over 700 times more rapid at pH 10 (t_1/2 = 1.2 hr.) than at pH 7 (t_1/2 = 864 hr.) in buffered deionized water. The average pH of the rice paddy was 8, but diurnal fluctuations of 7 to 9.5 are common in similar environments. Impurities in the water, sunlight, and temperature influence the rate of carbofuran loss but not nearly so much as pH. There was no evidence for significant loss due to evaporation or oxidation. The results have important implications for the duration of the insecticide's activity and the effect on fish within or downstream from treated paddies.     

Activity concentrations and dose rates from decorative granite countertops

The gamma radiation emitted from a variety of commercial decorative granites available for use in U.S. homes has been measured with portable survey meters as well as an NaI(Th) gamma spectrometer. The ⁴⁰K, U-nat, and ²³²Th activity concentrations were determined using a full-spectrum analysis. The dose rates that would result from two different arrangements of decorative granite slabs as countertops were explored in simulations involving an adult anthropomorphic phantom.     

A sorption kinetics model for arsenic adsorption to magnetite nanoparticles

Introduction  

Arsenic is a well known water contaminant that causes toxicological and carcinogenic effects. In this work magnetite nanoparticles were examined as possible arsenic sorbents. The objective of this work was to develop a sorption kinetics model, which could be used to predict the amount of arsenic adsorbed by magnetite nanoparticles in the presence of naturally occurring species using a first-order rate equation, modified to include adsorption, described by a Langmuir isotherm.