Interpreting early land management through compound specific stable isotope analyses of archaeological soils

Compound specific stable isotope analyses of managed soils using isotope ratio mass spectrometry have been undertaken as a means of determining early land use practices. delta (15)N amino acid signals demonstrate differences between manured grassland, unmanured grassland and continuous cereal cultivation under long-term experimental land use control conditions, with delta (15)N in hydrophobic amino acids providing the most distinctive signals. Analysis of early modern/medieval and of Bronze age anthropogenic soils from Orkney demonstrates that such signals are retained in archaeological contexts. delta (13)C analyses of n- alkanoic acid components of the fossil, Bronze Age, anthropogenic soils suggest a major terrestrial input to these soils, with uniform composition of formation materials. Surficial soils demonstrate the assimilation of isotopically lighter carbon, providing a means of assessing the mobility of the n- alkanoic acids within soils and sediments. Copyright 1999 John Wiley & Sons, Ltd.     

Conditioned real self-similar Markov processes

In recent work, Chaumont et al. (2013) showed that is possible to condition a stable process with index $\alpha \in (1,2)$ to avoid the origin. Specifically, they describe a new Markov process which is the Doob $h$-transform of a stable process and which arises from a limiting procedure in which the stable process is conditioned to have avoided the origin at later and later times. A stable process is a particular example of a real self-similar Markov process (rssMp) and we develop the idea of such conditionings further to the class of rssMp. Under appropriate conditions, we show that the specific case of conditioning to avoid the origin corresponds to a classical Cramér–Esscher-type transform to the Markov Additive Process (MAP) that underlies the Lamperti–Kiu representation of a rssMp. In the same spirit, we show that the notion of conditioning a rssMp to continuously absorb at the origin also fits the same mathematical framework. In particular, we characterise the stable process conditioned to continuously absorb at the origin when $\alpha \in (0,1)$. Our results also complement related work for positive self-similar Markov processes in Chaumont and Rivero (2007).     

Synthesis of 3-Dipeptidyl-2,4(1H,3H)-Quinazolinediones as Potential Anti-Hypertensive Agents

Quinazolinediones bearing a dipeptide side chain have been synthesized as potential anti-hypertensive agents.     

Triphosgene/Triphenylphosphine: A Mild Reagent for the Conversion of Alcohols to Chlorides

A mixture of triphosgene/triphenylphosphine in methylene chloride converts primary and secondary alcohols to chlorides at room temperature.     

“Solid Phase Synthesis of Cis-Coniferyl Alcohol”

Synthesis of cis-coniferyl alcohol (4-hydroxy-5-methoxy-cinnamyl alcohol), using support on Wang's resin is described.     

Two new parameters based on distances in a receiver operating characteristic chart for the selection of classification models

There are several indices that provide an indication of different types on the performance of QSAR classification models, being the area under a Receiver Operating Characteristic (ROC) curve still the most powerful test to overall assess such performance. All ROC related parameters can be calculated for both the training and test sets, but, nevertheless, neither of them constitutes an absolute indicator of the classification performance by themselves. Moreover, one of the biggest drawbacks is the computing time needed to obtain the area under the ROC curve, which naturally slows down any calculation algorithm. The present study proposes two new parameters based on distances in a ROC curve for the selection of classification models with an appropriate balance in both training and test sets, namely the following: the ROC graph Euclidean distance (ROCED) and the ROC graph Euclidean distance corrected with Fitness Function (FIT(λ)) (ROCFIT). The behavior of these indices was observed through the study on the mutagenicity for four genotoxicity end points of a number of nonaromatic halogenated derivatives. It was found that the ROCED parameter gets a better balance between sensitivity and specificity for both the training and prediction sets than other indices such as the Matthews correlation coefficient, the Wilk's lambda, or parameters like the area under the ROC curve. However, when the ROCED parameter was used, the follow-on linear discriminant models showed the lower statistical significance. But the other parameter, ROCFIT, maintains the ROCED capabilities while improving the significance of the models due to the inclusion of FIT(λ).     

Intermolecular Carbonyl–olefin Metathesis with Vinyl Ethers Catalyzed by Homogeneous and Solid Acids in Flow

The carbonyl–olefin metathesis reaction has experienced significant advances in the last seven years with new catalysts and reaction protocols. However, most of these procedures involve soluble catalysts for intramolecular reactions in batch. Herein, we show that recoverable, inexpensive, easy to handle, non‐toxic, and widely available simple solid acids, such as the aluminosilicate montmorillonite, can catalyze the intermolecular carbonyl–olefin metathesis of aromatic ketones and aldehydes with vinyl ethers in‐flow, to give alkenes with complete trans stereoselectivity on multi‐gram scale and high yields. Experimental and computational data support a mechanism based on a carbocation‐induced Grob fragmentation. These results open the way for the industrial implementation of carbonyl–olefin metathesis over solid catalysts in continuous mode, which is still the origin and main application of the parent alkene–alkene cross‐metathesis.     

Uniaxial exchange flows of two Bingham fluids in a cylindrical duct

Buoyancy driven flows of two Bingham fluids in an inclined ductare considered, providing a simplified model for many oilfieldcementing processes. The flows studied are near-uniaxial andstratified, with the heavy fluid moving down the incline, displacingthe lighter fluid upwards. Existence and uniqueness resultsare obtained for quite general flows and for those which satisfyan axial flow rate constraint. Parametric dependence of thesolutions on the axial pressure gradient is studied. Flows whichsatisfy a zero net axial flow constraint result from an axialpressure gradient which minimizes the viscous dissipation, butnot the plastic dissipation. A regularization method is usedto compute solutions to these problems for (more or less) arbitraryfluid-fluid interfaces and duct-cross sections. Examples relatedto a number of practical applications are presented.