A multi-objective approach to determine alternative targets in data envelopment analysis

The choice for radial projections of classic data envelopment analysis (DEA) models, resulting in a number of projections onto the Pareto-inefficient portion of the frontier, has been seen lately as a disadvantage in DEA. The search for a non-radial projection method resulted in developments such as preference structure models. These models consider a priori preference incorporation, using weights in the search for the most preferred efficient target, although presenting some implementation difficulties. In this paper, we propose a multi-objective approach that determines the bases for a posteriori preference incorporation, through individual projections of each variable (input or output) as an objective function, thus allowing one to obtain a target at every extreme-efficient point on the frontier. This multi-objective approach is shown to be equivalent to the preference structure models, yet presenting some advantages, such as the mapping of the possible weights, assigned to partial efficiencies of an observed unit, in order to reach a specific target.     

Structural investigation of reconstituted high density lipoproteins by scanning tunnelling microscopy

Being able to participate in the reverse cholesterol transport (RCT), high density lipoproteins (HDL) are known to be anti-atherogenic. In order to understand such a process, it is thus essential to have a detailed knowledge of the structure and molecular organisation of HDL.

Reconstituted nascent high density lipoproteins (r-HDL), consisting of synthetic phospholipids together with different apolipoproteins (apo A-I, A-IV and E), were thus analysed by scanning tunnelling microscopy (STM).

Both shape and dimensions of the discoidal HDL particles measured by this technique were found in good agreement with the data available from the literature.

The accuracy of the STM pictures presented in this paper enables for the first time the visualisation of the molecular organisation of such macromolecules. The arrangement of the protein as antiparallel helical segments, is consistent with the general mode of organisation of apolipoprotein/phospholipid discoidal particles previously reported.     

Syntheses and reactions of some fluorinated dienes,cyclobutenes and furans

There are many reports¹ of the pyrolysis of fluorinated organic compounds, including the defluorination of cyclic fluorocarbons over iron to give aromatic compounds. Extending this technique we have investigated the flow pyrolysis of some readily accessible unsaturated fluorocarbons, such as I, II, and III, and found these to be synthetically

useful routes to fluorinated dienes, cyclobutenes, and furans. Pyrolyses were carried out using a nitrogen flow over platinum, iron or caesium fluoride heated at 430–700°. The various products can all be rationalized in terms of intermediate allylic radicals, and the solid substrate influences which allylic radicals are formed.We are also investigating the chemistry of those now accessible compounds, such as IV, V, and VI, and some of the preliminary results are described.

For example the fluoride ion induced dimerisation of IV gave two major products VII and VIII via a particular interesting mechanism.

     

Hypersurfaces exceptionnelles des endomorphismes de ℂℙ(n)

Resumé  On étudie les hypersurfaces exceptionnelles pour les applications holomorphes de (n). On montre qu'une telle hypersurface n'est jamais lisse dès que son degré est plus grand que deux.

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Exceptional hypersurfaces for holomorphic endomorphisms of (n) are studied. We prove that such an hypersurface is not smooth as soon as its degree is greater than two.

     

Sorption of inorganic nanoparticles in woven cellulose fabrics

Titanium dioxide was deposited from aqueous suspension onto cellulosic surfaces.Titania was sourced from Degussa (P25TM,70:30 anatase:rutile).Dry uptake of particles was shown to be rapid and dominant with one-third of the deposition occurring in less than 30 s and over one-half in the first minute.Isotherms were recorded to compare the rate of titanium deposition on dry and pre-wetted cotton.In the dry case uptake reached a maximum in 30 min whereas in the pre-wetted case the uptake was seen to continue beyond 180 min.A broad trend of higher deposition occurring at lower pH was seen,corresponding to the region where surface charges were opposite and thus attractive.Dry pickup was less significant at high pH.The response to varying ionic strength was complex and was attributed to the combined effect of charge screening,particle aggregation and consequent particle entrapment or occlusion.Titania deposition into the interstices of woven cotton sheets resulted in the formation of inorganic,nanoparticulate skeletons which could be isolated by controlled combustion of the cellulose and thus cotton was suggested to have potential for the templated synthesis of high surface area semiconductor materials.     

Integrating Geographical Information Systems and Multi-Criteria Methods: A Case Study

This paper presents an application of the integration between Geographical Information Systems (GIS) and Multi-Criteria Decision Analysis (MCDA) to aid spatial decisions. We present a hypothetical case study to illustrate the GIS–MCDA integration: the selection of the best municipal district of Rio de Janeiro State, Brazil, in relation to the quality of urban life. The best municipal district is the one that presents the closest characteristics to those considered ideal by the decision-maker. The approach adopted is the Multi-Objective Linear Programming (MOLP) and the chosen method is the Pareto Race.     

Software-switching between direct absorption and wavelength modulation spectroscopy for the investigation of ADC resolution requirements

We present a tunable diode laser spectrometer that can be software-switched between a wavelength modulation spectroscopy (WMS) operation mode and the direct absorption spectroscopy (DAS) technique on a per-scan basis. The new setup allows a direct comparison between the two techniques under equal hardware and system environment conditions. In this work, we compare the impact of analog-to-digital converter resolution for operation in WMS and DAS mode. Example concentration evaluations show that in the DAS approach, relative absorptions smaller than the least significant bit can be measured with scan averaging and FIR-filtering applied. With full resolution, both techniques show similar performance in our setup, with a slight advantage for the WMS implementation.     

Denjoy-Wolff theorems for Hilbert’s and Thompson’s metric spaces

We study the dynamics of fixed point free mappings on the interior of a normal, closed cone in a Banach space that are nonexpansive with respect to Hilbert’s metric or Thompson’s metric. We establish several Denjoy-Wolff type theorems which confirm conjectures by Karlsson and Nussbaum for an important class of nonexpansive mappings. We also extend and put into a broader perspective results by Gaubert and Vigeral concerning the linear escape rate of such nonexpansive mappings.     

An <Emphasis Type="Italic">L</Emphasis>-approach for packing (<Emphasis Type="Italic">ℓ</Emphasis>, <Emphasis Type="Italic">w</Emphasis>)-rectangles into rectangular and <Emphasis Type="Italic">L</Emphasis>-shaped pieces

This paper presents an approach using a recursive algorithm for packing (?, w)-rectangles into larger rectangular and L-shaped pieces. Such a problem has actual applications for non-guillotine cutting and pallet/container loading. Our motivation for developing the L-approach is based on the fact that it can solve difficult pallet loading instances. Indeed, it is able to solve all testing problems (more than 20 000 representatives of infinite equivalence classes of the literature), including the 18 hard instances unresolved by other heuristics. We conjecture that the L-approach always finds optimum packings of (?, w)-rectangles into rectangular pieces. Moreover, the approach may also be useful when dealing with cutting and packing problems involving L-shaped pieces.