Trace metal distribution coefficients in the Mersey Estuary,UK: evidence for salting out of metal complexes

An examination of partition data for trace metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) from a number of independent studies conducted in a highly contaminated, organic-rich estuary (Mersey, UK) indicates an increase in the sediment-water distribution coefficient, KD, with increasing salinity for all metals with the excepton of Cd. This behavior is not consistent with inorganic speciation calculations or empirical modeling studies in other estuaries, which predict an inverse relationship between KD and salinity due to competitive adsorption and complexation with seawater ions. The data are, however, well-defined by an empirical model based on the salting out of neutral organic chemicals and yield salting constants in the range 0.7-2.0 L mol(-1). It is suggested that trace metals are complexed by and, subsequently, neutralize organic ligands, and that the resulting neutral assemblages are salted out, possibly via electrostriction. Examination of sorption date from other environments suggests that the effect may be more general in highly contaminated or organic-rich estuaries, and that a specific pool of relatively large, but undefined ligands, is mainly responsible.     

Efficient Protection in MPλS Networks Using Backup Trees: Part One—Concepts and Heuristics

Multi-protocol lambda switching (MPS) has recently been applied in the optical network control plane to provide fast lightpath provisioning. As an increasing amount of traffic is carried in optical transport networks (OTNs), single network failures can affect a vast amount of traffic, making lightpath protection crucial. Therefore, shared backup tree (BT) lightpath protection is a promising paradigm in MPS networks due to its ability of fast recovery and its efficiency in consumed resources. A shared BT is used to protect a group of working lightpaths towards the same destination. From the working lightpaths in such a group, only one affected lightpath at a time can be recovered using the BT. The main problem is how to group and route the working paths (WPs) and how to route the BTs, in such a way that the capacity resources used by the WPs and the BTs are minimized. In Part One of this study (presented in this paper), we propose three approaches to cope with this problem. The first approach is a purely integer linear programming (ILP) based method. The second one is a combination of ILP and a heuristic technique. The last one is a purely heuristic approach. In this paper, these approaches are theoretically compared. In Part Two [1] of this study, several simulations are carried out in order to compare these approaches in terms of performance and computing effort. The experimental results are in line with the theoretical expectations.     

Fourier analysis near-field polarimetry for measurement of local optical properties of thin films

We present measurements of the local diattenuation and retardance of thin-film specimens by using techniques that combine near-field scanning optical microscopy (NSOM) and a novel polarization-modulation (PM) polarimetry utilizing Fourier analysis of the detected intensity signal. Generally, quantitative near-field polarimetry is hampered by the optical anisotropy of NSOM probes. For example, widely used aluminum-coated pulled-fiber aperture probes typically exhibit a diattenuation near 10%. Our analysis of aperture diattenuation demonstrates that the usual techniques for nulling a PM polarimeter result in a nonzero residual probe retardance in the presence of a diattenuating tip. However, we show that both diattenuation and retardance of the sample can be determined if the corresponding tip properties are explicitly measured and accounted for in the data. In addition, in thin films (<100 nm thick), where the sample retardance and diattenuation are often small, we show how to determine these polarimetric quantities without requiring alignment of the fast and diattenuating axes, which is a more general case than has been previously discussed. We demonstrate our techniques by using two types of polymer-film specimens: ultrahigh molecular weight block copolymers (recently noted for their photonic activity) and isotactic polystyrene spherulites. Finally, we discuss how changes in the tip diattenuation during data collection can limit the accuracy of near-field polarimetry and what steps can be taken to improve these techniques.     

Wireless telephones and the risk of road crashes

In light of the rapidly increasing development of the cell phone market, the use of such equipment while driving raises the question of whether it is associated with an increased accident risk; and if so, what is its magnitude. This research is an epidemiological study on two large cohorts, namely users and non-users of cell phones, with the objective of verifying whether an association exists between cell phone use and road crashes, separating those with injuries.The Société de l'Assurance Automobile du Québec (SAAQ) mailed a questionnaire and letter of consent to 175000 licence holders for passenger vehicles. The questionnaire asked about exposure to risk, driving habits, opinions about activities likely to be detrimental to driving and accidents within the last 24 months. For cell phone users, questions pertaining to the use of the telephone were added. We received 36078 completed questionnaires, with a signed letter of consent. Four wireless phone companies provided the files on cell phone activity, and the SAAQ the files for 4 years of drivers' records and police reports. The three data sources were merged using an anonymized identification number. The statistical methods include logistic-normal regression models to estimate the strength of the links between the explanatory variables and crashes.The relative risk of all accidents and of accidents with injuries is higher for users of cell phones than for non-users. The relative risks (RR) for injury collisions and also for all collisions is 38% higher for men and women cell phone users. These risks diminish to 1.1 for men and 1.2 for women if other variables, such as the kilometres driven and driving habits are incorporated into the models. Similar results hold for several sub-groups. The most significant finding is a dose-response relationship between the frequency of cell phone use, and crash risks. The adjusted relative risks for heavy users are at least two compared to those making minimal use of cell phones; the latter show similar collision rates as do the non-users.     

Volatile constituents of the essential oil of Monodora myristica (Gaertn) dunal

The essential oil of Monodora myristica was obtained by steam distillation with a yield of 45-6 g kg^?1. The composition of the oil was analysed by gas chromatography and gas chromatography-mass spectrometry. The oil was found to contain 75% monoterpene hydrocarbons; the major compounds being α-phellandrene (50–4%), α-pinene (5–5%) and myrcene (4–35%). There were also a few sesquiterpene hydrocarbons (3%) and oxygenated compounds such as germacrcne-D-4-ol (9–5%). Germacrene-D-4-ol, α-pinene, Δ²-carene, β-caryophyllene, valencene. γ-muurolol and carvacryl acetate have not previously been reported in M myristica.     

Application de la méthode de la phase stationnaire à des réflecteurs d’ouverture carrée

This paper deals with the computation of a function defined by an integral whose integrand is a highly oscillatory function. The radiation integral in electromagnetism, for example, belongs to this class of integrals. The author use the stationary phase method to obtain an analytical expression of this integral asymptotic expansion and its remainder for which an upper bound is easy to find. The interest of the given formulation lies in the possibilities to compute the asymptotic expansion and to control the value of its remainder, for any order. Thus, an optimal accuracy can be obtained. Moreover, the author develops from this formulation an implementation of the algorithms, which, on one hand is general with respect to the expansion order and, on the other hand, is efficient because of its recursivity characteristics. In this paper, the integration domain is square and the second kind stationary points are only considered. However, the principles of a generalisation for an elliptic or polygonal integration domain and for first kind stationary points are put forward.