Fuzzy versus quantitative association rules: a fair data-driven comparison.

As opposed to quantitative association rule mining, fuzzy association rule mining is said to prevent the overestimation of boundary cases, as can be shown by small examples. Rule mining, however, becomes interesting in large databases, where the problem of boundary cases is less apparent and can be further suppressed by using sensible partitioning methods. A data-driven approach is used to investigate if there is a significant difference between quantitative and fuzzy association rules in large databases. The influence of the choice of a particular triangular norm in this respect is also examined.     

Crossflow microfiltration of gum arabic solutions: Comparison of the classical system with the co-current permeate flow system

Gum arabic is a natural gum exuded mainly by the trees Acacia senegal , currently used in the food industries for its emulsifying, thickening and stabilizing properties. Its present processing includes various operations providing a quite turbid product. Crossflow microfiltration could be interesting for the clarification and the cold-pasteurization of the gum arabic solutions. Several experiments were therefore made with the crossflow microfiltration unit at ENSIA, using two different systems: the classical one (without permeate circulation), and the co-current permeate flow system (CCPF) allowing the exploration of the low transmembrane pressures range. With gum arabic solutions of 0.17g solids g⁻¹ solution and 70°C, the best results after 60 min of filtration (105.7 L h⁻¹ m⁻², 4.4% of solids retention and 83.4% of clarification) were obtained with the CCPF system at low transmembrane pressure and high crossflow velocity (0.3 bar and 7.5ms⁻¹).     

Temperature-induced phase change in a fat. A study by electron spin resonance

Electron Spin Resonance, Differential Scanning Calorimetry and rheological techniques have been used to study the physical changes induced by temperature in lard and in the solid and liquid fractions obtained by fractionation of lard at 15 C. The mobilization process of a C18 fatty acid nitroxide derivative dispersed in the molten fat has been observed in the temperature range −50 to +70 C. The mobilization of the probe seemed to be concomitant with the melting of the low melting point glycerides. Above this temperature, all the probes were in the liquid phase and their mobility reflected the viscosity of their liquid environment, or the viscosity of the bulk fat when crystal was no longer present. Probe mobility was temperature dependent, and it was identical for the three fats at the same temperature, despite their different triglyceride compositions.     

Modelling of the substrate heterogeneities experienced by a limited microbial population in scale-down and in large-scale bioreactors

A methodology based on stochastic modelling is presented to describe the influence of the bioreactor heterogeneity on the microorganisms growth and physiology. The stochastic model is composed of two sub-models: a microorganism circulation sub-model and a fluid mixing sub-model used for the characterization of the concentration gradient. The first one is expressed by a classical stochastic model (with random number generation), whereas the second one is expressed by a stochastic Markov chain. Their superimposition permits to obtain the concentration profiles experienced by the microorganisms in the bioreactor. The simulation results are expressed in the form of frequency distributions. At first, the study has been focused on the design of scale-down reactors (SDR). This kind of reactor has been reported to be an efficient tool to study at a small-scale the hydrodynamic behaviour encountered in large-scale reactor [P. Neubauer, L. Horvat, S.O. Enfors, Influence of substrate oscillations on acetate formation and growth yield in Escherichia coli glucose limited fed-batch cultivations, Biotechnol. Bioeng. 47 (1995) 139–146]. Several parameters affecting the shape of the frequency distributions have been tested. Among these, it appears that the perturbation frequency, the exposure time and the design of the non-mixed part of the SDR have a significant influence on the shape of the distributions. The respective influence of all these parameters must be taken into account in order to obtain representative results. As a general trend, the increase of the recirculation flow rate between the mixed and the non-mixed part of the SDR induce a shift of the frequency distribution for the lower relative concentrations, which suggests an attenuation of the scale-down effect. This has been validated by using the SDR in the case of the cultivation of Saccharomyces cerevisiae. However, the influence of the non-mixed part of the SDR is not quite well understood if only taking account of the frequency distribution analysis, and supplementary experiments are required to elucidate the underlying mechanism.

The aspect of the frequency distributions suggests that both the design and the operating conditions of a scale-down reactor need to be adjusted in order to match the behaviour of a given large-scale reactor. Examples of frequency distributions obtained in the case of large-scale reactors are given.     

Index of critical points in rational l-approximation

This article is concerned with the l²-approximation of a given transfer function f by a rational one whose order is prescribed. We show that the sum of the indices of the critical points of the criterion is generically equal to 1, and in particular does not depend on f.     

Interest of epitopic dissection in immunoanalysis of proteins and peptides: review of theoretical and practical aspects

AIM: To assess cell proliferation in early prostate cancer and associated pathological lesions. METHODS: Using the Ki-67 antibody, the cell proliferation index was measured in early stage prostatic carcinoma in 37 incidental tumours diagnosed at transurethral prostatectomy (TURP) and in 20 low volume cancers treated by radical prostatectomy. Proliferation indexes have also been measured in areas of normal peripheral zone, transition zone hyperplasia, atrophic appearing lobules, and high grade prostatic intraepithelial neoplasia in the radical prostatectomy cases. RESULTS: In the TURP series the proliferation index correlated with grade and stage. Logistic regression analysis, however, showed that Gleason grade was the most reliable predictor of biopsy proven residual disease and clinical progression. In the radical series transition zone carcinoma the proliferation index was half that of peripheral zone carcinoma. The atrophic lobules also showed a high proliferation index of the same order as seen in the peripheral zone carcinoma. Normal peripheral zone showed the lowest proliferation index and in hyperplastic transition zone it was also less than the other areas. CONCLUSIONS: There is only limited support for the correlation of proliferation index with grade in early stage prostatic carcinoma. The findings do not suggest that proliferation index adds to the prognostic information given by grade and stage in pT1 disease. The significant difference in proliferation index in transition zone and peripheral zone carcinomas supports the morphological distinction of these tumour types and is consistent with differences in biological behaviour. The high proliferation index in lobules considered morphologically atrophic is reminiscent of previous observations in which carcinoma was spatially associated with atrophy.     

Systemic release of soluble TNF receptors after high-dose TNF in isolated limb perfusion

Isolated limb perfusion (ILP) with high dose tumour necrosis factor (TNF), interferon gamma and melphalan (TIM) is an efficient treatment for patients with regionally advanced melanoma and sarcoma. In 44 patients, we determined the kinetics of soluble TNF receptors (sTNF-RI and RII) plasma concentrations, and correlated them with systemic TNF and interleukin 6 (IL-6) levels and shock. Seven patients treated conventionally by ILP without cytokine served as controls. Elevated levels of both sTNF-Rs were observed within 30 min after beginning of the TIM-ILP. A first peak of sTNF-Rs levels was observed 3 h after ILP and was followed by a rapid decrease reaching a nadir at 12-14 h post ILP. This first peak was followed by a second, long-lasting elevation of both sTNF-Rs levels persisting for 4 to 5 days after TIM-ILP. Patients treated by ILP without TNF/interferon gamma (IFN-gamma) had no detectable increase in either sTNF-Rs or in circulating TNF, demonstrating that the release of TNF-Rs was dependent upon the administration of TNF/IFN-gamma. High plasma levels of TNF and IL-6 were observed in patients that had more than 5% leakage during the TIM-ILP, but no significant correlation between TNF levels and the peak values of both sTNF-Rs was observed. The levels of TNF and IL-6 were, however, significantly related to each other. TNF systemic levels, but not sTNF-Rs concentrations, correlated significantly with the severity of the shock observed after TIM-ILP. Patients in which sTNF-RII concentration was in excess over circulating TNF, had no shock or grade I shock only, suggesting that sTNF-RII may play a protective, although limited, role in inhibiting activity of circulating TNF.     

Microstructure and Mechanical Properties of Hot-Pressed Silicon Carbide-Aluminum Nitride Compositions

A flexural strength of up to 1 GPa was achieved in SiC-AIN materials and is attributed to a dense, equiaxial grain structure of the 2H(δ) SiC-AIN solid solution, with a relatively uniform grain size of ∼ 1 μm. The strength was found to decrease with increasing grain size. While the β→α phase transformation and the formation of various metastable polytypes make microstructural control difficult in SiC materials, excellent control is facilitated in SiC-AIN materials as a result of the stable 2H solid solution. Several mechanisms of grain refinement during the β→ 2H transition were observed, most notably the direct formation of several 2H grains from a single β grain. In addition, grain growth is limited by the diffusion-controlled nature of the transition. These mechanisms could be utilized to achieve even higher strength values, with potentially higher reliability of the materials in structural applications.     

Formation mechanism and ceramic process of the ferroelectric perovskites: Pb (Mg13Nb23)O3 and Pb (Fe12Nb12)O3

The formation of the $\text{Pb}\text{(}\text{Mg}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ and Pb $\text{(}\text{Fe}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$$\text{Nb}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)}\text{O}{}_3$ phases with a perovskite type structure is directly dependent on the reactivity of magnesium and ferric oxides to other phases belonging to the binary system PbO  Nb₂O₅. Moreover, it is shown that the ceramic process influences the proportion of perovskite phases in comparison with parasite phases and also the densification of the samples. The optimization of the ceramic process allows to obtain a pure $\text{Pb(Fe}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{Nb}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{O}{}_3$ phase, but as far as $\text{Pb(Mg}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ is concerned, a parasite phase is never entirely eliminated.