Mergers

Using small matched samples of companies which are, and are not, highly involved in acquisition in the period 1986-90, an investigation is mounted to ascertain whether "acquisitiveness" has any impact upon the remuneration of the top directors over and above what one would expect because of the growth in "size". The evidence suggests it does, if returns to share options are included in the measure of remuneration.

Inhibition of monocyte complement receptor enhancement by low molecular weight material from human lung cancers

We have studied the effect of dialysates from lung cancer homogenates to alter both the expression of complement (C3b) receptors per se and also to inhibit leucoattractant-induced enhancement of complement rosettes on monocytes from healthy individuals. Enhancement and enhancement-inhibition by tumour extracts were compared with material derived from normal lung excised from distance from the tumour. There was no significant difference between tumour homogenate (TH) and normal lung homogenate (NLH) in terms of enhancement of complement rosettes per se. In contrast, TH produced a dose- and time-dependent inhibition of leucoattractant-induced enhancement of C3b rosettes which was significantly different from that obtained with NLH. This enhancement-inhibition was observed with four undifferentiated, four squamous and three adenocarcinomas of lung. The degree of enhancement-inhibition was not related to the type of tumour or varying accompanying histological features such as necrosis and the degree of infiltration with inflammatory cells. Following gel filtration on Sephadex G-50 each type of cancer gave a major peak of inhibitory activity which eluted with molecules having an apparent molecular size of approximately 3,000 daltons. A second larger peak (8,000-10,000 daltons) was also detected with extracts from the undifferentiated and adenocarcinomas. These results support previous findings, mainly from experimental animals, indicating that 'anti-macrophage/monocyte principles' are elaborated from certain tumour types

Quantifying temporal and spatial variations in sediment, nitrogen and phosphorus transport in stream inflows to a large eutrophic lake

High-frequency sampling of two major stream inflows to a large eutrophic lake (Lake Rotorua, New Zealand) was conducted to measure inputs of total suspended sediment (TSS), and fractions of nitrogen and phosphorus (P). A total of 17 rain events were sampled, including three during which both streams were simultaneously monitored to quantify how concentration–discharge (Q) relationships varied between catchments during similar hydrological conditions. Dissolved inorganic nitrogen (DIN) concentrations declined slightly during events, reflecting dilution of groundwater inputs by rainfall, whereas dissolved inorganic P (PO₄–P) concentrations were variable and unrelated to Q, suggesting dynamic sorptive behaviour. Event loads of total nitrogen (TN) were predominantly DIN, which is available for immediate uptake by primary producers, whereas total phosphorus (TP) loads predominantly comprised particulate P (less labile). Positive correlations between Q and concentrations of TP (and to a lesser extent TN) reflected increased particulate nutrient concentrations at high flows. Consequently, load estimates based on hourly Q during storm events and concentrations of routine monthly samples (mostly base flow) under-estimated TN and TP loads by an average of 19% and 40% respectively. Hysteresis with Q was commonly observed and inclusion of hydrological variables that reflect Q history in regression models improved predictions of TN and TP concentrations. Lorenz curves describing the proportions of cumulative load versus cumulative time quantified temporal inequality in loading. In the two study streams, 50% of estimated two-year loads of TN, TP and TSS were transported in 202–207, 76–126 and 1–8 days respectively. This study quantifies how hydrological and landscape factors can interact to influence pollutant flux at the catchment scale and highlights the importance of including storm transfers in lake loading estimates

The Effects of Clearcutting and Glyphosate Herbicide Use on Parasitic Wasps in Maine Forests

Parasitic wasps (parasitoids) play an important role as natural enemies of insects and contribute substantially to world biodiversity (May, 1988), yet they have received relatively little attention outside of agricultural settings. Clearcut harvesting and herbicide (glyphosate) application are frequent and widespread disturbances in Maine forests that drastically alter the local environment. Parasitoids are particularly susceptible to disturbance for several reasons: 1) they are vulnerable to small changes in environmental conditions, 2) they occupy a high trophic level, and 3) many are host specific. However, there may be potential benefits of disturbance such as increased food resources (floral nectaries) and increased abundance and diversity of hosts. This thesis discusses a study of several wasp taxonomic families within managed forest in western Maine. To investigate the effects of clearcut timber harvesting and glyphosate application on parasitoids this study compared five forest treatment types to mature forest in western Maine (Somerset county). The forest types consisted of young (35 years since harvest) glyphosate treated clearcuts, young untreated clearcuts, old (1421 years since harvest) glyphosate treated clearcuts, old untreated clearcuts, plantations (1417 years since harvest, glyphosate treated, and planted with black spruce seedlings), and mature forest (more than 50 years old). Wasp communities were sampled using two malaise traps in each replicated forest treatment type throughout the summers of 2000 and 2001. To investigate the relationship between floral resources and parasitoid abundance in forest ecosystems, floral communities were sampled in each site along four 40m linear transects. Although not always significant, parasitoid abundance at the family level tended to be greater in plantations and lower in young clearcuts compared to mature forest. Braconidae abundance tended to be greater in old clearcuts compared to mature forest, but equivalent for other families. At the family level, parasitoid abundance was not affected by glyphosate. The effect of forest type on parasitoid morphospecies was inconsistent in 2000 and 2001. The effect of floral communities on wasp family abundance was inconsistent between years, but overall appeared to have no effect. However, the abundance of the native perennial plant, bunchberry (Cornus canadensis), was correlated with the abundance of Ichneumonidae, Braconidae, and Pompilidae, as well as several morphospecies. Chalcidoidea abundance was correlated with the abundance of wild strawberry (Fragaria spp.). Taken together, the results of this study suggest that clearcutting has an overall negative shortterm effect on parasitoid abundance, but a positive (particularly when replanted with spruce) or neutral longterm effect. These effects appear to be unrelated to floral community, but specific floral species may provide direct benefit or be indicators. Host availability, microclimate and habitat complexity are likely to be important factors to consider for future studies of this nature

A development of logistics management models for the Space Transportation System

A new analytic queueing approach was described which relates stockage levels, repair level decisions, and the project network schedule of prelaunch operations directly to the probability distribution of the space transportation system launch delay. Finite source population and limited repair capability were additional factors included in this logistics management model developed specifically for STS maintenance requirements. Data presently available to support logistics decisions were based on a comparability study of heavy aircraft components. A two-phase program is recommended by which NASA would implement an integrated data collection system, assemble logistics data from previous STS flights, revise extant logistics planning and resource requirement parameters using Bayes-Lin techniques, and adjust for uncertainty surrounding logistics systems performance parameters. The implementation of these recommendations can be expected to deliver more cost-effective logistics support

Exploiting the interplay of quantum interference and backbone rigidity on electronic transport in peptides: a step towards bio-inspired quantum interferometers

Accepted 29th November 2016Electron transfer in peptides provides an opportunity to mimic nature for applications in bio-inspired molecular electronics. However, quantum interference effects, which become significant at the molecular level, have yet to be addressed in this context. Electrochemical and theoretical studies are reported on a series of cyclic and linear peptides of both β-strand and helical conformation, to address this shortfall and further realize the potential of peptides in molecular electronics. The introduction of a side-bridge into the peptides provides both additional rigidity to the backbone, and an alternative pathway for electron transport. Electronic transport studies reveal an interplay between quantum interference and vibrational fluctuations. We utilize these findings to demonstrate two distinctive peptide-based quantum interferometers, one exploiting the tunable effects of quantum interference (β-strand) and the other regulating the interplay between the two phenomena (3₁₀-helix).Jingxian Yu, John R. Horsley and Andrew D. Abel

A Majorization Algorithm for Constrained Correlation Matrix Approximation

We desire to find a correlation matrix of a given rank that is as close as possible to an input matrix R, subject to the constraint that specified elements in must be zero. Our optimality criterion is the weighted Frobenius norm of the approximation error, and we use a constrained majorization algorithm to solve the problem. Although many correlation matrix approximation approaches have been proposed, this specific problem, with the rank specification and the constraints, has not been studied until now. We discuss solution feasibility, convergence, and computational effort. We also present several examples

A Majorization Algorithm for Constrained Correlation Matrix Approximation

We desire to find a correlation matrix of a given rank that is as close as possible to an input matrix R, subject to the constraint that specified elements in must be zero. Our optimality criterion is the weighted Frobenius norm of the approximation error, and we use a constrained majorization algorithm to solve the problem. Although many correlation matrix approximation approaches have been proposed, this specific problem, with the rank specification and the constraints, has not been studied until now. We discuss solution feasibility, convergence, and computational effort. We also present several examples