Showing papers by "Conservatoire national des arts et métiers published in 1994"

Enzymatic browning reactions in apple and apple products

Abstract: This review examines the parameters of enzymatic browning in apple and apple products that is, phenolic compounds, polyphenoloxidases, and other factors (ascorbic acid and peroxidases), both qualitatively and quantitatively. Then the relationships between intensity of browning and the browning parameters are discussed, including a paragraph on the methods used for browning evaluation. Finally, the different methods for the control of browning are presented.

From structured documents to novel query facilities

Abstract: Structured documents (e.g., SGML) can benefit a lot from database support and more specifically from object-oriented database (OODB) management systems. This paper describes a natural mapping from SGML documents into OODB's and a formal extension of two OODB query languages (one SQL-like and the other calculus) in order to deal with SGML document retrieval.Although motivated by structured documents, the extensions of query languages that we present are general and useful for a variety of other OODB applications. A key element is the introduction of paths as first class citizens. The new features allow to query data (and to some extent schema) without exact knowledge of the schema in a simple and homogeneous fashion.

Fluorescence energy transfer as a probe for nucleic acid structures and sequences.

Abstract: The primary or secondary structure of single-stranded nucleic acids has been investigated with fluorescent oligonucleotides, i.e., oligonucleotides covalently linked to a fluorescent dye. Five different chromophores were used: 2-methoxy-6-chloro-9-amino-acridine, coumarin 500, fluorescein, rhodamine and ethidium. The chemical synthesis of derivatized oligonucleotides is described. Hybridization of two fluorescent oligonucleotides to adjacent nucleic acid sequences led to fluorescence excitation energy transfer between the donor and the acceptor dyes. This phenomenon was used to probe primary and secondary structures of DNA fragments and the orientation of oligodeoxynucleotides synthesized with the alpha-anomers of nucleoside units. Fluorescence energy transfer can be used to reveal the formation of hairpin structures and the translocation of genes between two chromosomes.

A double stable isotope technique for measuring iron absorption in infants.

Abstract: A stable isotope technique has been developed which uses 57Fe and 58Fe as labels and which enables the simultaneous measurement of Fe absorption from two test meals in infants. The method was evaluated by measuring Fe absorption from a commercial whey-adjusted infant formula in nine healthy infants aged 13-25 weeks. Each infant was fed 210 ml formula, labelled with either 57Fe or 58Fe, on four consecutive mornings, in random order. The total Fe content in each feed was 2.5 mg Fe; either as 2.5 mg 57Fe, or 0.6 mg 58Fe plus 1.9 mg Fe with normal isotopic composition. Isotopic enrichment of Fe in erythrocytes was measured by thermal ionization mass spectrometry 14 d after the last administration, and Fe absorption was calculated based on isotope ratio shifts, total circulating Fe and intake of each isotope. Geometric mean absorption for the 57Fe and 58Fe labels was 6.72 and 6.58% respectively, and the absorption of the two isotopes was not significantly different (Student's paired t test). By this technique, paired comparisons of Fe absorption can be obtained and systematic studies of the influence of dietary factors on Fe absorption during infancy can be conducted.

Iron bioavailability studied in infants: the influence of phytic acid and ascorbic acid in infant formulas based on soy isolate.

Abstract: The influence of phytic acid and ascorbic acid content of soy formula on iron (Fe) bioavailability was investigated in infants by analysis of the incorporation of stable isotopes of Fe into red blood cells 14 d after administration using a double stable isotope technique. Paired comparisons were made with each infant acting as his or her own control. The geometric mean fractional Fe incorporation into red blood cells increased from 5.5 to 6.8% (p < 0.05) when soy formula with the native content of phytic acid was compared with a 83% dephytinized formula. A more pronounced effect was shown with soy formula containing no phytic acid; the mean fractional Fe incorporation increased from 3.9 (native phytic acid) to 8.7% (zero phytic acid; p < 0.001). A significant (p < 0.01) effect was also demonstrated when the Fe:ascorbic acid molar ratio in the native phytate-containing formula was increased from 1:2.1 to 1:4.2; mean fractional Fe incorporation increased from 5.9 to 9.6%. These results demonstrate that the Fe bioavailability from soy-based infant formulas can be similarly increased by either removing phytic acid or increasing the ascorbic acid content.

Vitamin status of a healthy French population: dietary intakes and biochemical markers.

Abstract: The vitamin status of a representative population sample in a French district in the Paris area was assessed using a biochemical and dietary approach. Complete data were obtained for 1039 subjects 6 to 97 years old. Dietary intakes of most vitamins increased up to adolescence and then remained stable or decreased slightly in adult life. Total vitamin intakes were higher in men than in women (except for ascorbic acid), but the vitamin density of the diet was higher in females. Most subjects presented dietary intakes below the French recommended allowances for vitamin B1, B6, C, A and E. A variation in biochemical parameters according to age and sex was observed only for serum concentration of retinol, beta-carotene, vitamin E and C. Multiple regression analysis showed that dietary vitamin intakes were related to the biological status for vitamin B2, B6, C, folates, beta-carotene and vitamin E. Tobacco smoking, alcohol consumption and oral contraceptive were significantly correlated with biological status for several vitamins. While biochemical evidence of severe vitamin deficiency was not observed, a sizeable minority of the French population is not lavishly supplied with some vitamins, and this situation deserves investigation to see if any deleterious effects are associated with it.

Iron Status of a Healthy French Population: Factors Determining Biochemical Markers

Abstract: The iron status of a representative population sample in a district of Paris area (France) was assessed using a biochemical and dietary approach. Complete data were obtained for 1,108 subjects 6 months to 97 years old. Total iron intake increased up to adolescence and then remained stable in adult life. Iron intake was higher in men than in women. Most children and menstruating women presented a dietary iron intake below the recommended allowances. While anemia was not very common, iron deficiency (defined as the existence of at least two abnormal values in the four independent indicators of iron status: serum ferritin, erythrocyte protoporphyrin, transferrin saturation and MCV) was particularly common in infants, young children, menstruating women and elderly men. Serum ferritin, erythrocyte protoporphyrin and transferrin saturation were significantly correlated with inflammatory markers. Significant correlations were found between dietary total iron and serum ferritin (r = 0.29, p < 0.001) and hemoglobin (r = 0.44, p < 0.001). After adjustment for age, sex and inflammation, using multiple linear regression models, the relationship between both heme and nonheme iron intake and serum ferritin remained significant. Serum ferritin and hemoglobin levels were negatively correlated with calcium and phosphorus intake.

A Hamiltonian approach to stabilization of nonholonomic mechanical systems

Abstract: A simple procedure is provided to write the equations of motion of controlled mechanical systems with constraints as controlled Hamiltonian equations with respect to a "Poisson" bracket which does not necessarily satisfy the Jacobi-identity. Based on the Hamiltonian form a stabilization procedure is proposed. >

Annals of telecommunications

Abstract: This international journal publishes original peer-reviewed papers in the field of telecommunications. It covers all the essential branches of modern telecommunications, ranging from digital communications to communication networks and the internet, to software, protocols and services, uses and economics. This large spectrum of topics accounts for the rapid convergence through telecommunications of the underlying technologies in computers, communications, content management towards the emergence of the information and knowledge society.

A Hamiltonian approach to stabilization of nonholonomic mechanical systems

Abstract: A simple procedure is provided to write the equations of motion of controlled mechanical systems with constraints as controlled Hamiltonian equations with respect to a "Poisson" bracket which does not necessarily satisfy the Jacobi-identity. Based on the Hamiltonian form a stabilization procedure is proposed. >

Two Lipoxygenases from Germinated Barley‐Heat and Kilning Stability

Abstract: Using ammonium sulfate precipitation followed by hydrophobic and ion exchange chromatography, two lipoxygenase isoenzymes, LOX 1 and LOX 2, were 18.3- and 44.5-fold purified from germinated barley, with 18 and 24% recovery of activity respectively. LOX 1 and LOX 2 were characterized by isoelectric points 4.9 and 6.4, and molecular weights of 90 kd and 110 kd, respectively. Apparent Km values for linoleic acid were 0.06 mM for LOX 1 and 0.18 mM for LOX 2. LOX 1 converted linoleic acid to 9 and 13 hydroperoxides at about 4:1, whereas the 13 hydroperoxide was the major product formed by LOX 2 (ratio 3:7). For both isoforms, thermal inactivation data indicated first order kinetics with activation energies influenced by ionic strength and pH. Isoenzymes composition was analyzed for three kilning schemes: the 1:3 ratio between LOX 1 and LOX 2 observed in germinated barley increased during the course of kilning.

Coumarinic Fluorescent Chemosensors for the Detection of Transition Metal Ions

Abstract: Fluoroionophores consisting of coumarin-153 linked to mono- and diaza-crown ethers are able to complex transition metal cations (Ni2+, Zn2+, Cd2+) and Pb2+, with concomitant large changes in photophysical properties. The stability constants in acetonitrile are higher than 3×106 M −1 except for Ni2+.

Relationship between urinary iodine concentration and hearing capacity in children.

Abstract: Urinary iodine excretion was assessed in 1222 healthy children aged 10 months (n = 456), 2 years (n = 368) and 4 years (n = 398) living in the Paris area and originating from continental France (55.2%), North Africa (15.7%), the West Indies (9.7%), West Africa (8.2%), Southeast Asia (5.5%), and southern Europe (5.7%). Iodine excretions (median values) were, respectively, 18.1, 13.4 and 11.6 micrograms/100 ml at 10 months, 2 years and 4 years, and risk of mild to moderate iodine deficiency (< 10 micrograms/100 ml) was 18.0%, 32.3% and 37.2% for the same age groups. Urinary iodine excretion was highest among Southeast Asian children, and lowest among West Africans. Hearing acuity was measured either by conventional mono-aural pure-tone audiometry or by binaural free field testing depending on the child's age. Hearing loss at 4000 Hz and average hearing impairment at speech frequencies (500, 1000 and 2000 Hz) were more severe among children at risk of mild to moderate iodine deficiency (less than 10 micrograms/100 ml) compared with those with urinary excretion above 10 micrograms/100 ml.

High CO2 levels reduce ethylene production in kiwifruit

Abstract: The effects of CO2 on ethylene production rates and on the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene have been investigated in kiwifruit [Actinidia deliciosa (A. Chev.) Liang and Ferguson, cv. Hayward] pericarp tissues. Carbon dioxide concentrations up to 10% notably reduced ethylene production rates but did not affect ACC levels. Carbon dioxide levels from 10 to 28.5% slightly reduced wound-induced ACC accumulation but resulted in only a slight additional reduction in ethylene production. However, in the presence of saturating amounts of ACC, ethylene formation was stimulated by high CO2: levels. The apparent Vmax and Km for ACC of the in vivo conversion of ACC to ethylene were both increased by high CO2 although to a different extent. When CO2 concentrations were increased from 0.2 to 28.5%, the Vmax varied from 50 to 90 nl g–1 h–1 while the Km for ACC increased from 15 to 72 μM. Thus, the Vmax over Km ratio, which represents the efficiency of ACC conversion to ethylene when ACC concentrations are very low, was reduced by 40% in the presence of 5% CO2 and by 60% in the presence of 28% CO2. The concentrations of ACC, at which ACC, oxidase was inhibited by high CO2 are comparable to the concentrations found in the fruit. It is therefore suggested that the reduction of ethylene production rates in fruits by high CO2 might be exerted at least partially at the level of the conversion of ACC to ethylene.

Organic Substrate and Electrolyte Solutions for Oral Rehydration in Diarrhea

Abstract: INTRODUCTION .. 322 Glucose-Oral Rehydration Solution (G-ORS): An Effective Treatment of Dehydration 322 Why Should Other Organic Substrates Be Considered as Alternatives to Glucose? 323 Is the Electrolyte Composition of the G-ORS Optimal for Rehydration? ......... . 324 SUBSTRATES CHOSEN ON THE BASIS OF PHYSIOLOGICAL CONSIDERA nONS . . . . . . . . . . . . . . . . . . .. .. . . . . . .. . . . . . . . . . . . . . . . . 325

Occurrence Graphs for Interval Timed Coloured Nets

Abstract: We present an approach to construct the occurrence graph for ITCPN (Interval Timed Coloured Petri Nets). These models, defined by Van Der Aalst in [VAN] can simulate other timed Petri nets and allow to describe large and complex real-time systems. We define classes as sets of states between two occurrences, and we use these classes to define the occurrence graph of an ITCPN. Then an equivalence relation based on time is defined for classes, and we show that occurrence graphs reduced using this equivalence relation are finite if and only if the set of reachable markings is finite. These graphs can be used to verify all the dynamic properties such as reachability, boundedness, home, liveness and fairness properties but also performance properties: minimal and maximal bounds along a occurrence sequence or a cycle. Finally we complete delay based equivalence with a colour based equivalence in order to achieve further reduction.

Multiple Representation Modelling and Querying

Abstract: One challenge in spatial data modelling is related to multiple representation of geographic objects. While often associated with cartographic change of scale and generalization, it applies in fact to a wider range of data analysis situations. We discuss multiple representation issues from a data modelling point of view, with emphasis on hierarchical structures inherent to multiple resolution levels. Then, we consider specific features related to multiple representation from a database modelling and querying point of view. Some guidelines for extending the object-oriented query language O2SQL are finally given. Although motivated by spatial applications, this extension is useful for a variety of other applications such as cooperative query answering [CCL91]. In particular it allows querying without exact data knowledge.

An efficient deadlock avoidance control policy in FMS using structural analysis of Petri nets

Abstract: The aim of this paper is to cope with deadlocks occurring in FMS where different sequential processes share many distinct resources. The Petri net model of the class of FMS considered is a bounded asymmetric choice net called PAC net. In this paper, we propose a deadlock avoidance control policy based on the structural analysis of Petri nets. Our method first adds the "local control places" to ensure that the minimal deadlocks which are not trapped remain always marked. We then prove that the restriction of the augmented net's evolution to safe markings (states) is sufficient to avoid any global deadlock. The safety property is defined in terms of a marking condition on the "local control places" and the principle of the method "never grant a resource that takes the system from a safe to an unsafe state" is easy to implement. >

Partitioning Problems in Cluster Analysis: A Review of Mathematical Programming Approaches

Abstract: Three main mathematical programming approaches have been followed to design exact algorithms for partitioning problems in cluster analysis: cutting-planes, branch-and-bound and recently, column generation combined with integer programming. These approaches are reviewed and evaluated, using two versions of the clique partitioning problem for illustration.

New extractant for selective recovery of palladium from high level radioactive waste

Abstract: Use of di- or tri-thioether instead monothioether permits to increase both efficiency and selectivity of the extraction of palladium. This selectivity allows the separation of palladium contained in nuclear fuel reprocessing solution in a single step.

A new concept of photogeneration of cations: Evidence for photoejection of Ca(2+) and Li (+) from complexes with a crown-ether-linked merocyanine by picosecond spectroscopy.

Abstract: Time-resolved transient absorption and gain spectra of DCM-crown and its complexes with Li+ and Ca2+ in acetonitrile are measured in the wavelength range 370–670 nm after subpicosecond excitation at 425 nm. The results give evidence for the fast formation of free DCM-crown from both excited complexes, with a faster rate for the Li+ complex. A two-step mechanism is found for the initial decay (within 30 ps) of the free DCM-crown.