Direct observation of charge inversion by multivalent ions as a universal electrostatic phenomenon

We have directly observed reversal of the polarity of charged surfaces in water upon the addition of tri- and quadrivalent ions using atomic force microscopy. The bulk concentration of multivalent ions at which charge inversion reversibly occurs depends only very weakly on the chemical composition, surface structure, size and lipophilicity of the ions, but is dominated by their valence. These results support the theoretical proposal that spatial correlations between ions are the driving mechanism behind charge inversion.Comment: submitted to PRL, 26-04-2004 Changed the presentation of the theory at the end of the paper. Changed small error in estimate of prefactor ("w" in first version) of equation

An approach to the modelling of stability of waste containers during urban flooding

Before the solid waste is dumped in landfills, the collection process for large Spanish cities starts from a regular collection of household waste municipal service which is carried out through street containers. When an urban flood occurs those containers may lose their stability, thereby allowing debris (i.e., solid waste contained) and leachate to escape from the container and contaminate the flood water. Moreover, once a container loses its stability it can further constrict a narrow street and increase flooding, thereby creating a closed basin with no outlet for runoff and exacerbating the effects of flooding. Therefore, the waste containers stability when exposed to flooding is definitely an environmental, safety and health concern to be addressed. In this research stability functions for waste containers exposed to urban floods have been derived. These thresholds have been employed to analyse the containers'' potential behaviour during floods in Barcelona. In order to validate the model a historical rainfall has been modelled and low-return-period design storms (i.e., 1, 5, and 10 years) have been used to assess the containers vulnerability against floods for frequent rainfall events. Once the number of potentially unstable containers has been estimated, an adaptation measure has been proposed in order to increase the resilience of waste sector against urban floods in Barcelona

Mothers' complex talk when sharing books with their toddlers: Book genre matters

This study investigated the influence of book genre (narrative or didactic) on mothers' language use during a book sharing interaction with their 18- to 25-month-olds. Mother-child dyads were videotaped sharing both a narrative and a didactic book, adapted from two commercially available books, and matched in terms of length, quantity of text, and target content. A greater proportion of mothers' talk was complex (i.e., predictions, text-to-life comparisons) during narrative book sharing than during didactic book sharing. Mothers also used a greater variety of verb tenses and referenced more mental states during narrative book sharing. These results differ from findings from previous studies with older children where it has been concluded that didactic books offer greater opportunities for complex talk than narrative books. The results also highlight the importance of taking situational factors into account when investigating parent-child communicative interactions. © The Author(s) 2013

Modelling the spatial distribution of DEM Error

Assessment of a DEM’s quality is usually undertaken by deriving a measure of DEM accuracy – how close the DEM’s elevation values are to the true elevation. Measures such as Root Mean Squared Error and standard deviation of the error are frequently used. These measures summarise elevation errors in a DEM as a single value. A more detailed description of DEM accuracy would allow better understanding of DEM quality and the consequent uncertainty associated with using DEMs in analytical applications. The research presented addresses the limitations of using a single root mean squared error (RMSE) value to represent the uncertainty associated with a DEM by developing a new technique for creating a spatially distributed model of DEM quality – an accuracy surface. The technique is based on the hypothesis that the distribution and scale of elevation error within a DEM are at least partly related to morphometric characteristics of the terrain. The technique involves generating a set of terrain parameters to characterise terrain morphometry and developing regression models to define the relationship between DEM error and morphometric character. The regression models form the basis for creating standard deviation surfaces to represent DEM accuracy. The hypothesis is shown to be true and reliable accuracy surfaces are successfully created. These accuracy surfaces provide more detailed information about DEM accuracy than a single global estimate of RMSE

A probabilistic model of the economic risk to Britain’s railway network from bridge scour during floods

Scour (localized erosion by water) is an important risk to bridges, and hence many infrastructure networks, around the world. In Britain, scour has caused the failure of railway bridges crossing rivers in more than 50 flood events. These events have been investigated in detail, providing a data set with which we develop and test a model to quantify scour risk. The risk analysis is formulated in terms of a generic, transferrable infrastructure network risk model. For some bridge failures, the severity of the causative flood was recorded or can be reconstructed. These data are combined with the background failure rate, and records of bridges that have not failed, to construct fragility curves that quantify the failure probability conditional on the severity of a flood event. The fragility curves generated are to some extent sensitive to the way in which these data are incorporated into the statistical analysis. The new fragility analysis is tested using flood events simulated from a spatial joint probability model for extreme river flows for all river gauging sites in Britain. The combined models appear robust in comparison with historical observations of the expected number of bridge failures in a flood event. The analysis is used to estimate the probability of single or multiple bridge failures in Britain's rail network. Combined with a model for passenger journey disruption in the event of bridge failure, we calculate a system-wide estimate for the risk of scour failures in terms of passenger journey disruptions and associated economic costs

High INDO (indoleamine 2,3-dioxygenase) mRNA level in blasts of acute myeloid leukemic patients predicts poor clinical outcome

Indoleamine 2,3-dioxygenase degrades the amino acid tryptophan which is essential for T cells. Tryptophan depletion causes T-cell cycle arrest and solid tumors that express high levels of indoleamine 2,3-dioxygenase can create immune suppression. Recently, blasts of patients with acute myeloid leukemia were shown to express indoleamine 2,3-dioxygenase. We determined INDO (encoding gene for indoleamine 2,3-dioxygenase) mRNA expression in leukemic blasts of 286 patients with acute myeloid leukemia by gene-expression profiling. Results were validated by quantitative polymerase chain reaction analysis in blasts of an independent cohort of 71 patients. High INDO expression was correlated to significantly shortened overall and relapse-free survival. Correlation of INDO expression to relevant known prognostic factors and survival identified high INDO expression as a strong negative independent predicting variable for overall and relapse-free survival. Inhibition of indoleamine 2,3-dioxygenase expressed by myeloid leukemic blasts may result in breaking immune tolerance and offers new therapeutic options for patients with acute myeloid leukemia

High INDO (indoleamine 2,3-dioxygenase) mRNA level in blasts of acute myeloid leukemic patients predicts poor clinical outcome

Indoleamine 2,3-dioxygenase degrades the amino acid tryptophan which is essential for T cells. Tryptophan depletion causes T-cell cycle arrest and solid tumors that express high levels of indoleamine 2,3-dioxygenase can create immune suppression. Recently, blasts of patients with acute myeloid leukemia were shown to express indoleamine 2,3-dioxygenase. We determined INDO (encoding gene for indoleamine 2,3-dioxygenase) mRNA expression in leukemic blasts of 286 patients with acute myeloid leukemia by gene-expression profiling. Results were validated by quantitative polymerase chain reaction analysis in blasts of an independent cohort of 71 patients. High INDO expression was correlated to significantly shortened overall and relapse-free survival. Correlation of INDO expression to relevant known prognostic factors and survival identified high INDO expression as a strong negative independent predicting variable for overall and relapse-free survival. Inhibition of indoleamine 2,3-dioxygenase expressed by myeloid leukemic blasts may result in breaking immune tolerance and offers new therapeutic options for patients with acute myeloid leukemia