The successive reduction of data subsets: A new method for estimating parameters of thermodynamic models

The successive reduction method allows the fitting of models to large sets of data using microcomputers of moderate memory size. It relies on the assumption that the information brought by a set of data is summarized by the maximum likelihood parameters and their inverse variance—covariance matrix. The parameters are estimated from the last data subset, taking account of the information brought by the former ones. The successive reduction method is compared with the classical 'global' method. They give exactly the same results for linear models. With a non-linear model, equivalent results are obtained when this model is consistent with the data. Applications are presented, relating to parameter estimation for generalized equations of state, to vapour—liquid equilibrium and excess enthalpy data reduction using the NRTL and UNIQUAC models.     

Hybrid Systems and Hybrid Computation 1st Part: Hybrid Systems

In the first part of this paper we will give a short historical survey of the field of hybrid systems, a precise definition of a hybrid system and some comments on the definition. In a second paper (Hybrid systems and hybrid computation – 2nd part: Hybrid computation) we will concentrate on a particular aspect of the theory closely related to scientific computation, that we have called hybrid computation.     

Cytotoxic triterpenoid saponins from the roots of Cephalaria gigantea

Three new oleanane-type saponins, giganteosides L (1), M (2) and N (3) along with eight known ones were isolated from the roots of Cephalaria gigantea. Their structures were established as 3-O-[beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl]-28-O-[beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl]-oleanolic acid, 3-O-[beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl]-28-O-[beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl]-hederagenin, 3-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucuronopyranosyl]-28-O-[beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl]-hederagenin, respectively, by means of spectroscopic methods (1D and 2D NMR, HR-ESI-MS). Cytotoxic activity of monodesmosides was investigated in vitro using three cancer cell lines, namely, human non pigmented melanoma MEL-5 and human leukemia HL-60. Giganteosides D (4) and E (5) showed antiproliferative effect on human cell lines with IC(50) values in the range 3.15-7.5 microM.     

Even Cycles in Graphs with Many Odd Cycles

It will be shown that if G is a graph of order n which contains a triangle, a cycle of length n or n−1 and at least cn odd cycles of different lengths for some positive constant c, then there exists some positive constant k=k(c) such that G contains at least kn ^1/6 even cycles of different lengths. Other results on the number of even cycle lengths which appear in graphs with many different odd length cycles will be given. Received: October 15, 1997     

Epoxyesters p‐menthaniques et pinaniques en milieu basique – Parfum de noix de coco

Base‐Induced Reactions of p ‐ Menthane‐ and Pinane‐Derived Epoxyesters – Coconut Fragrance The base‐induced isomerization of p‐menthane‐ and pinane‐derived epoxy esters was studied. The reaction is dependent on the structure of the terpene compound, the nature of the base, and experimental conditions. Among all the new synthesized compounds, one, 6a , emits a very strong fragrance of coconut. In the structure of this tricyclic lactone, the presence of a methyl substituent is essential.     

Antiplasmodial activity of three bisbenzylisoquinoline alkaloids from the tuber of Stephania rotunda

Three bisbenzylisoquinoline alkaloids were isolated for the first time from Stephania rotunda tuber. Their structures were elucidated by spectroscopic methods and their antiplasmodial activity was investigated in vitro on chloroquine resistant Plasmodium falciparum strain W2. These alkaloids were identified as 2-norcepharanthine (1), cepharanoline (2) and fangchinoline (3). In vitro, they displayed significant antiplasmodial activity with inhibitory concentration 50 values of 0.3, 0.2 and 0.3 μM.     

The effect of long-term unilateral deafness on the activation pattern in the auditory cortices of French-native speakers: influence of deafness side

Background  

In normal-hearing subjects, monaural stimulation produces a normal pattern of asynchrony and asymmetry over the auditory cortices in favour of the contralateral temporal lobe. While late onset unilateral deafness has been reported to change this pattern, the exact influence of the side of deafness on central auditory plasticity still remains unclear. The present study aimed at assessing whether left-sided and right-sided deafness had differential effects on the characteristics of neurophysiological responses over auditory areas. Eighteen unilaterally deaf and 16 normal hearing right-handed subjects participated. All unilaterally deaf subjects had post-lingual deafness. Long latency auditory evoked potentials (late-AEPs) were elicited by two types of stimuli, non-speech (1 kHz tone-burst) and speech-sounds (voiceless syllable/pa/) delivered to the intact ear at 50 dB SL. The latencies and amplitudes of the early exogenous components (N100 and P150) were measured using temporal scalp electrodes.