Determination of the biodegradable fraction of dissolved organic matter in waters

Two bioassay procedures are proposed for determining biodegradable dissolved organic carbon (BDOC) in waters. Both involves sterile filtration of the sample, reinoculation with a natural assemblage of bacteria from the same origin as the sample, and incubation for at least 10 days in the dark at 20°C. In the first procedure, dissolved organic carbon (DOC) is followed, until a plateau is reached and the difference between initial and final DOC is taken as a measure of BDOC. In the second procedure, bacterial biomass and mortality rate are followed and the integrated flux of mortality during the incubation period is calculated and divided by the growth yield to give an estimate of BDOC. Both procedures provide closely concordant results.An example of application to the study of ozonation and biological activated carbon filtration in drinking water treatment is presented.     

Influence of built environment on pedestrian's crossing decision

The objective of this experimental study is to identify the differentiation made by pedestrians, in their crossing decision, between various urban environments, notably in terms of perception of walking pleasantness and safety. This experiment further aims to identify the environmental features that pedestrians take into account and the inferences they develop and use to explain their road crossing decision. Sets of photographs presenting five different environments (city center, inner suburbs, public housing in the outskirts, commercial zone in the outskirts and countryside) were presented to 77 participants divided up into three age groups (pre-adolescents, young and middle adults). Their decision to cross or not, their perception of pleasantness and safety, and the elements they take into account to make a decision were collected for each environment presented. The quantitative results show the pedestrians’ perceptions of the pleasantness and safety of public spaces, in terms of walking, largely vary with urban environments. Moreover, the crossing decision significantly varies according to the environment. Pedestrians were significantly more inclined to take the decision to cross in city center than in the other sites presented. The qualitative analysis of the interviews shows that the presence and function of the buildings, the quality of the sidewalks and the marked parking spaces are key factors to explain their crossing decision, by enabling them to infer the density of pedestrians and traffic and the vehicle speed.     

A new probabilistic scheme for information retrieval in hypertext

Abstract

The aim of probabilistic models is to define a retrieval strategy within which documents can be optimally ranked according to their relevance probability, with respect to a given request. In this scheme, the underlying probabilities are estimated according to a history of past queries along with their relevance judgments. Having evolved over the last twenty years, these estimations allow us to take both document frequency and within-document frequency into account.

In the current study, we suggest representing documents not only by index term vectors as proposed by previous probabilistic models but also by considering relevance hypertext links. These relationships, which provide additional evidence on document content, are established according to requests and relevance judgments, and may improve the ranking of the retrieved records, in a sequence most likely to fulfill user intent. Thus, to enhance retrieval effectiveness, our learning retrieval scheme should modify: (1) the weight assigned to each indexing term, (2) the importance attached of each search term, and (3) the relationships between documents. Using a simple additive scheme applied after a ranked list of documents has been determined, with the aid of a probabilistic retrieval strategy, our proposed solution is well suited to a hypertext system. Based on the CACM test collection which includes 3,204 documents and the CISI corpus (1,460 documents), we have built a hypertext and evaluated our proposed retrieval scheme. The retrieval effectiveness of this approach presents interesting results.     

Timing During Interruptions in Timing.

Duration and location of breaks in time interval production were manipulated in various conditions of stimulus presentation (Experiments 1-4). Produced intervals shortened and then stabilized as break duration lengthened, suggesting that participants used the break as a preparatory period to restart timing as quickly as possible at the end of the break. This interpretation was supported in Experiment 5, in which similar results were obtained with a reaction time response executed at the end of the break. In all experiments, produced intervals lengthened as the break occurred later during the interval. The authors conclude that varying break location and duration reveal, respectively, the influence of attentional time-sharing before the interruption and of preparatory processes taking place during the break. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nonmaternal care in infancy and emotional/behavioral difficulties at 4 years old: Moderation by family risk characteristics.

The authors examined the role of familial risk and child characteristics in the association between the type of child care in infancy (maternal care [MC]) versus nonmaternal care [NMC]) and emotional/behavioral difficulties at 4 years old. Canadian families (N=1,358) with children between 1 and 12 months old were followed over 4 years. Family risks were found to moderate the association between type of child care and physical aggression. MC in infancy was associated with lower levels of physical aggression among children from a low-risk family background but not among those from a high-risk family background. The effect size was small (d=-0.16; confidence interval [CI]=-0.3, -0.01). Family risk and the sex of the child moderated the association between child care and emotional problems. MC in infancy was associated with a lower level of emotional difficulties among girls from low-risk families but not among boys or among children from high-risk families. The effect size was moderate (d=-0.44; CI=-0.65, -0.23). The study indicates that the effect of child care type in infancy varies by family and child characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chemistry, biology, and QSAR studies of substituted biaryl hydroxamates and mercaptoacetamides as HDAC inhibitors-nanomolar-potency inhibitors of pancreatic cancer cell growth

The histone deacetylases (HDACs) are able to regulate gene expression, and inhibitors of the HDACs (HDACIs) hold promise in the treatment of cancer as well as a variety of neurodegenerative diseases. To investigate the potential for isoform selectivity in the inhibition of HDACs, we prepared a small series of 2,4'-diaminobiphenyl ligands functionalized at the para-amino group with an appendage containing either a hydroxamate or a mercaptoacetamide group and coupled to an amino acid residue at the ortho-amino group. A smaller series of substituted phenylthiazoles was also explored. Some of these newly synthesized ligands show low-nanomolar potency in HDAC inhibition assays and display micromolar to low-nanomolar IC(50) values in tests against five pancreatic cancer cell lines. The isoform selectivity of these ligands for class I HDACs (HDAC1-3 and 8) and class IIb HDACs (HDAC6 and 10) together with QSAR studies of their correlation with lipophilicity are presented. Of particular interest is the selectivity of the mercaptoacetamides for HDAC6.