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Spores of psychrotolerant strains of the foodborne pathogen Bacillus cereus can multiply during storage of cooked or pasteurized, refrigerated foods and can represent a risk if these cells are not eliminated during reheating of food product before consumption. We determined the heat-resistance of psychrotolerant B. cereus vegetative cells at different heating temperatures in laboratory medium and compared it with that of thermotolerant B. cereus vegetative cells. The z values, based on times for a 3 logio reduction, of the vegetative cells of the three psychrotolerant phylogenetic groups of B. cereus varied between 3.02 degrees C and 4.84 degrees C. The temperature at which a 3 logio reduction was achieved in 10 min varied between 47.6 degrees C and 49.2 degrees C for psychrotolerant vegetative cells and it was around 54.8 degrees C for thermotolerant vegetative cells. Moreover, 0.4 min at 60 degrees C would be sufficient for a 6 logio CFU/ml reduction of the most heat resistant psychrotolerant B. cereus vegetative cells. These data clearly showed that psychrotolerant B. cereus vegetative cells can be rapidly eliminated by a mild heat treatment such as food reheating.

La betterave sucrière est la deuxième plante en termes de production de sucre avec 19,6% du sucre produit dans le monde entre 2015 et 2016, derrière la canne à sucre. Cultivée dans les zones tempérées comme le nord de la France et la Belgique, elle est sensible au stress thermique modéré. En effet, une augmentation de 1°C de la température moyenne entraîne une perte de rendement de 29%. Dans le cadre du réchauffement climatique et afin de fournir aux agriculteurs des variétés ayant une meilleure résistance à la chaleur, la compréhension des réponses de la betterave sucrière au stress hyperthermique est nécessaire. Pour cela, une étude des réponses physiologiques et métaboliques a été effectuée avec trois hybrides : un hybride de type sucré avec 18% de sucre dans sa racine, un hybride de type lourd avec un meilleur rendement que la moyenne mais avec seulement 17% de sucre dans sa racine, et un hybride dit « résistant » au stress hyperthermique, ayant le meilleur rendement aux champs avec des températures plus élevées. Alors que la photosynthèse nette n’était pas modifiée en condition de stress, une croissance plus rapide de la rosette a été observée aux stades jeunes pour les trois hybrides. Une approche de modélisation suggère qu’une croissance de la rosette plus rapide contrecarre les effets du stress hyperthermique sur la production racinaire. Cette hypothèse est confirmée par le fait que l’hybride le plus performant a la croissance foliaire la plus rapide. Le stress hyperthermique provoque une forte diminution du stockage transitoire du carbone dans les feuilles matures. Dans les feuilles en cours de développement, le stockage transitoire du carbone, dont la moitié sous forme d’amidon, était seulement maintenu chez l’hybride le plus performant. Un calcul intégrant les besoins en carbone de la croissance foliaire suggère que ce maintien contribue significativement au maintien du rendement chez cet hybride. Par ailleurs, un marqueur putatif de la sensibilité au stress hyperthermique a été identifié lors de cette étude. Au final ce travail a permis de mieux comprendre comment la betterave sucrière répond à l’élévation de la température et ainsi proposer de nouvelles stratégies pour l’amélioration de cette espèce

The aim of FP7-OPTIFEL project is to create new products based on fruits and vegetables, supplemented with nutrients to fight elderlies’ nutritional deficiencies. The microbial safety of these products is of great importance due to elderlies’ vulnerability. The foodborne pathogen Bacillus cereus can resist to pasteurization and psychrotrophic strains can multiply during food storage at low temperatures. Therefore we verified if psychrotrophic Bacillus cereus could be destroyed when reheating the food before consumption, by measure of the heat resistance of psychrotrophic Bacillus cereus vegetative cells. We studied six psychrotrophic strains belonging to three different phylogenetic groups (group II, V and VI) and two thermophilic strains (group VII) at temperatures representative of food reheating. These Bacillus cereus strains were cultivated in optimal condition and heat resistance was determined with vegetative cells in stationary phase. Bacillus cereus vegetative cells suspensions were heated at five or more different temperatures for five different heating times. Survival curves and thermal death curves were established and the kinetic parameters δ (decimal reduction time at temperature T) and Z (temperature dependence of δ) were derived by linear regression. At 48°C, δ value o vegetative cells of psychrotrophic strains varied from 3 to 8 min. For all strains, the heat-sensitivity (Z values) varied between 1.6 °C and 5.6 °C. Z value was not different among the Bacillus cereus phylogenetic groups, and similar between the psychrotrophic and thermophlic groups. These Z values were low compare to other bacteria, for example to Salmonella enterica Z value can varied between 7.71 and 11.19 and for Staphylococcus aureus between 7.46 and 13.98 (Amado et al., 2013). Six log 10 reduction of the most resistant psychrotrophic Bacillus cereus could be obtained by reheating 3 min at 53°C.

On estime aujourd'hui à 25% les pertes d'aliments post-récolte et en aval, en raison de leur altération par des microorganismes. L'étude menée ici illustre le risque d'altération engendré par une rupture dans la chaîne du froid, en prenant comme modèle un aliment liquide pasteurisé et réfrigéré, riche en nutriments et dont la température ne doit pas dépasser 4°C.

The aim of this study was to evaluate the efficiency of selection of potato families in early generations for heat tolerance. Thirty families were evaluated in the seedling generation (SG), first clonal generation (FCG) in the field and greenhouse under high temperature conditions, and second clonal generation (SCG) under mild temperatures. The mean of the families was obtained in each generation. The 16 most productive families in FCG were selected, and the clones of these families were evaluated in experiments in the winter and rainy crop seasons. The results showed that family selection for tuber shape may be applied as of the SG. It was also observed that family selection in the FCG and SCG for yield and tuber specific gravity contributed to identification of clones tolerant to heat and responsive to environmental improvement. Resumo O objetivo deste trabalho foi avaliar a eficiência da seleção de famílias de batata nas gerações precoces para tolerância ao calor. Foram avaliadas 30 famílias na geração seedling (SG), primeira geração clonal (FCG) em campo e casa de vegetação sob condições de temperaturas elevadas e segunda geração clonal (SCG) sob temperaturas amenas e obtidas as médias das famílias em cada geração. Foram selecionadas 16 famílias mais produtivas na FCG e os clones dessas famílias foram avaliados em experimentos nas safras de inverno e "das águas". Os resultados mostraram que a seleção de famílias para formato de tubérculos pode ser aplicada desde a SG. Também observou-se que a seleção de famílias na FCG e SCG para produtividade e peso específico de tubérculos contribuiu para a identificação de clones tolerantes ao calor e responsivos a melhoria ambiental.

The biophysical reactions of light harvesting and electron transport during photosynthesis take place in a uniquely constructed bilayer, the thylakoid. In all photosynthetic eukaryotes, the complement of atypical glycerolipid molecules that form the foundation of this membrane are characterised by sugar head-groups and a very high level of unsaturation in the fatty acids that occupy the central portion of the thylakoid bilayer. alpha-linolenic (18:3) or a combination of 18:3 and hexadecatrienoic (16:3) acids typically account for approximately two-thirds of all thylakoid membrane fatty acids and over 90% of the fatty acids of monogalactosyl diacylglycerol, the major thylakoid lipid [1, 2]. The occurrence of trienoic fatty acids as a major component of the thylakoid membrane is especially remarkable since these fatty acids form highly reactive targets for active oxygen species and free radicals, which are often the by-products of oxygenic photosynthesis. Photosynthesis is one of the most temperature-sensitive functions of plant [3, 4]. There remains a widespread belief that these trienoic fatty acids might have some crucial role in plants to be of such universal occurrence, especially in photosynthesis tolerance of temperature [5].

Caractérisation de la diversité génétique de [i]Moorella[/i] et [i]Geobacillus[/i] par M13-PCR. 9. Congrès National de la Société Française de Microbiologie

L'objectif du travail est de mettre en place des méthodes d'évaluation des risques microbiologiques et des bénéfices nutritionnels lors de la transformation des légumes, en vue d'une analyse risque-bénéfice. Le risque (industriel) considéré est l'altération des conserves de haricots verts due à la bactérie thermophile Geobacillus stearothermophilus, et le bénéfice nutritionnel est la teneur en vitamine C des haricots verts appertisés. Des paramètres de référence ont d'abord été acquis, par une méta-analyse par approche bayésienne pour la partie risque. Les paramètres de résistance thermique D à 121.1°C et pH 7, zT et zpH de G.stearothermophilus ont ainsi été estimés respectivement à 3.3 min, 9.1°C et 4.3 unités pH en moyenne en milieu aqueux. Les modèles risque et bénéfice ont ensuite été analysés par la méthode de simulation de Monte Carlo à deux dimensions, permettant une propagation séparée de la variabilité et de l'incertitude. Les pertes en vitamine C prédites par le modèle entre la matière première et les légumes appertisés sont de 86% en moyenne, et le taux de non-stabilité à 55°C prédit est de 0.5% en moyenne, globalement en accord avec la réalité. Une analyse risque-bénéfice a ensuite visé à optimiser le bénéfice tout en gardant le risque à un niveau acceptable, par exploration de scénarios d'interventions possibles basés sur les résultats d'analyses de sensibilité. Enfin, un modèle d'évaluation des risques dus à la bactérie pathogène Bacillus cereus dans une purée de courgettes a été confronté à des données de contamination dans des produits incubés, par le biais d'une inférence bayésienne., The aim of this work is to set up microbiological risk and nutritional benefit assessment methods in the transformation of vegetables, in view of a risk-benefit analysis. The considered (industrial) risk is the alteration of green bean cans due to thermophilic bacteria Geobacillus stearothermophilus, and the nutritional benefit is the vitamin C content in appertized green beans. Reference parameters have first been acquired, by a meta-analysis using Bayesian inference for the risk part. Thermal resistance parameters D at 121.1°C and pH 7, zT and zpH of G.stearothermophilus have been respectively estimated at 3.3 min, 9.1°C and 4.3 pH units on average in aqueous media. The risk and benefit models have then been analyzed by a two-dimensional Monte Carlo simulation method, allowing a separated propagation of uncertainty and variability. The vitamin C losses between fresh and appertized green beans predicted by the model are of 86% on average, and the predicted non-stability at 55°C rate is of 0.5% on average, in good accordance with reality. A risk-benefit analysis has then been carried out to optimize benefit while keeping risk at an acceptable level, by exploring possible intervention scenarios based on some sensibility analysis results. Finally, a risk analysis model involving pathogenic bacteria Bacillus cereus in a courgette puree has been confronted to incubated product contamination data, by means of a Bayesian inference.

Since feed costs comprise about 60 to 70% of the total costs of production, efforts to reduce feed costs is then a major preoccupation for increasing competitiveness of the pig industry. Understanding the factors that affect feed conversion in pigs can enable producer to more effectively combine various inputs in order to achieve a low feeding cost. There are many factors involved in reaching good feed efficiency including genetic, diet, feed, management, housing and environment. Temperature is the single most important environmental factor affecting the global farm feed efficiency. In ad libitum fed animals, changes in metabolic heat production are essential mechanisms to maintain body temperature within a physiologically safe range under cold or heat stress. These adjustments have direct consequences on energy intake and/or maintenance requirements which in turn could reduce energy efficiency as conversion of feed to tissue or other products. However, the low level of performance related to a thermal challenge can also be attributed to a direct effect of ambient temperature (independent of feed intake) on reproductive physiology, health, and energy metabolism. Finally, thermal stress could also be a major cause of pig mortality at birth, during the nursing period or thereafter, and could predispose pigs to mortality or morbidity by other causes (starvation, diseases, etc.). High mortality rates in nursing piglets or in finishing pigs have a significant impact on overall farm feed efficiency. The chapter describes how climatic environment impacts feed efficiency in pigs and reviews solutions that can be used in order to attenuate the effect of environmental temperature on feed efficiency.

Les exemples passés en revue incluent l’adaptation à des températures élevées, par des gènes influant sur la taille corporelle ou l’emplumement, ainsi que par l’apport de lignées locales. Vis-à-vis de l’intensité lumineuse, la réponse particulière du gène albinos lié au sexe en ce qui concerne la ponte est décrite. Des différences génétiques de réponse à la composition de l’aliment sont brièvement discutées, avec l’exemple d’un gène répandu dans les lignées de type "oeuf brun", responsable d’une odeur "de poisson" des oeufs en présence de tourteau de colza. Pour la résistance à des agents pathogènes spécifiques, en dehors des nombreuses études concernant le complexe majeur d’histocompatibilité ou d’autres gènes, l’apport de facteurs de résistance contenus dans des lignées locales est illustré dans le cas de la race égyptienne Fayoumi.

The sensitivity of photosynthesis to high temperature was investigated in greenhouse-grown saplings of three Mediterranean (Quercus canariensis Willd., Q. coccifera L. and Q. suber L.) and two temperate European oak species (Q. robur L. and Q. petraea Matt. Liebl.). The sensitivity to high temperature was inferred from F0T curves producing the critical temperature (Tc) at which a rapid rise in ground chlorophyll a fluorescence (F0) occurs. Tc is known to acclimate to moderately increased ambient temperature by displaying significant increases. We first checked whether acclimation of Tc was paralleled by an increase in optimal temperature for light driven electron flux (Topt,), recorded by measuring quantum yield of photochemistry under saturating CO2 and moderate irradiance. Saplings of Q. suber and Q. canariensis were submitted to four, five days long ambient temperature steps (15, 25, 35 and 15 °C again). Tc was usually largely above 45 °C while Topt was around 30-35 °C. Both increased with ambient temperature in the two species, and decreased again when temperature returned to the initial values. This recovery was nevertheless not complete after a week at 15 °C. A second experiment tested whether the plasticity of Tc was of the same extent in the five species. A significant increase of Tc followed by a decrease was detected in all species. Only small inter-specific differences were detected in Tc, and temperature induced plasticity was similar in the different species: Tc increased by about 4-5 °C while ambient temperature was increased from 15 to 35 °C. Mediterranean and European oaks did not differ in this respect. This result does not support the hypothesis that oak species from warmer regions would display a larger plasticity of Tc in response to increasing temperatures., La sensibilité de la photosynthèse à des températures élevées a été étudiée chez cinq espèces de chênes: trois méditerranéennes (Quercus canariensis Willd., Q. coccifera L. et Q. suber L.) et deux tempérées (Q. robur L. et Q. petraea Matt. Liebl.). La sensibilité aux fortes températures était estimée suivant la procédure des courbes F0T par la température critique (Tc) au dessus de la quelle la fluorescence de base de la chlorophylle (F0) augmente rapidement. Tc présente une forte capacité d'acclimatation et augmente sensiblement après une élévation modérée de la température ambiante. Dans une première expérimentation nous avons vérifié si une augmentation de Tc s'accompagnait d'une augmentation de la température optimale du transfert d'électrons durant la photochimie (Topt,), estimée par mesure du rendement quantique de la photochimie sous CO2 saturant sous éclairement modéré. Les jeunes plants de Q. suber et Q. canariensis ont été soumis à quatre températures ambiantes (15 °C, 25 °C, 35 °C et de nouveau 15 °C) pendant cinq jours. Tcatteignait des valeurs supérieures à 45 °C alors que Topt était aux alentours de 30-35 °C. Chez les deux espèces, ces paramètres ont augmenté avec la température ambiante et à nouveau diminué lors du retour à la température initiale. Nous avons conclu que le changement de la thermostabilité de la photochimie du PSII s'est accompagné d'un changement de la température optimale du transfert d'électrons photosynthétiques. Dans une deuxième expérimentation nous avons comparé Tc sur cinq espèces de chêne soumises à la même séquence climatique que précédemment. Tc et sa plasticité différaient très peu entre espèces: Tc a augmenté de 4-5 °C alors que la température ambiante passait de 15 à 35 °C. Les cinq espèces de chênes ne présentaient pas de différences marquées ni de valeur absolue de Tc, ni de plasticité de ce paramètre. Ces résultats ne confirment pas l'hypothèse que les espèces méditerranéennes de chêne présenteraient des valeurs plus élevées de Tc, ou une plus forte plasticité de ce paramètre que les espèces de régions tempérées.

The physiological processes contributing to photosynthesis (i.e., photochemistry, carbon reduction cycle, CO2 diffusion through stomata and to the chloroplasts) display different responses to high temperatures that still need to be better documented, despite the knowl-edge acquired during the past decades. The thermal optima of photochemistry and rubisco activity have been found to be around 35 and 38 C; but neither the inter and intra-specific diversity of this parameter, nor the ability of these optima to acclimate to rapidly changing environmental conditions have yet been clearly established. The thermal breakpoint of chlo-rophyll fluorescence is frequently used as one of the indexes for the thermostability of PSII and thylakoid membranes. This breakpoint is usually close to 45 C in many species. Recent experiments have shown that it is highly plastic, increases by up to 10 C being induced ei-ther by drought or by gradually increasing temperatures. In this presentation, we will summa-rise the information available in this field, as well as show the latest evidence documenting the plasticity of this parameter and the consequences it might have for the photosynthetic functions as a whole, basing on experiments with oak trees.

Not available, Cette étude est consacrée à la modélisation et a la mise au point de techniques de mesure de la résistance thermique de contact entre deux couches cylindriques. Nous avons développé un modèle tridimensionnel du transfert de chaleur en régime permanent. Ce modèle sert d'une part, à prédire le comportement thermique de deux cylindres en contact, et d'autre part, à analyser l'influence des divers paramètres mécaniques et thermiques sur la résistance de contact. Il ressort de l'analyse des calculs que, sauf cas exceptionnels, il est toujours possible de simplifier l'étude thermique de la résistance de contact entre deux cylindres par l'étude du contact entre deux plans. L'étude expérimentale porte sur la caractérisation de la résistance thermique de contact entre deux pièces d'un moteur à explosion. A cet effet, trois dispositifs expérimentaux ont été mis en place. La méthode impulsionnelle (méthode flash) s'avère être bien adaptée à la mesure de résistance thermique de contact pour des échantillons en géométrie cylindrique. Cette étude a permis de mettre en évidence l'influence de paramètres tels que: la pression de frettage, le matériau de l'échantillon, la température et l'épaisseur de l'échantillon. L'ensemble des résultats expérimentaux en régime transitoire et en régime permanent sont cohérents et en accord avec le modèle théorique

The purpose of roads in areas of seasonal frost is to attenuate frost penetration and thus permit the design pavement thickness to be reduced. Early indications from actual use are that polystyrene insulation will meet these requirements. Two 100-ft (32.8-m) sections of street were constructed in Sudbury, Ontario, Canada, in September 1964 using 2-by-4-ft by 2-in. (0.610-by l.220-m by 5.08-cm) sheets of extruded polystyrene insulation in the pavement structure at a depth of 16 in. (0.406 m). In the summer of 1965 two additional insulated road sections were constructed in Ottawa, Ontario, Canada. Two types of insulation and methods were used. Extruded polystyrene boards were placed by hand (the same as at Sudbury) at the desired elevation. Polyurethane was foamed in place by spraying the chemicals on the road bed with a specially constructed self-propelled spraying machine. This paper discusses the relative merits of the different methods of roads and, in a broader context, the protection against freezing of underground utilities, such as water mains and sewers.

The need for thermal resistance measurements on thick specimens (100 to 180 mm) of low-density thermal insulation and subsequent changes in ASTM test standards have increased the need for the evaluation of precision and accuracy attainable with the heat flow meter (HFM) apparatus. Such an evaluation is usually performed with transfer standards established on a guarded hot plate. The Division of Building Research of the National Research Council of Canada (DBR/NRCC) has developed a transfer standard and calibrated specimen bank to be used in verifying HMF test procedures and instrument error evaluation. This paper discusses such calibration and the use of the HFM apparatus and reviews the transfer standards developed at NRCC., Symposium on Guarded Hot Plate and Heat Flow Meter Methodology: 07 October 1982, Quebec City, Que., Canada

Specimens of glass fiber, phenolic foam, and extruded polystyrene foam insulation with moisture contents ranging up to about 25 percent by volume were mounted in the roof of an experimental building. The interior of the building was maintained at about 21 degrees C and normal weather conditions prevailed outside. Thermocouples were located at the upper and lower surface of each insulation specimen and at the quarter points of some specimens. A calibrated heat flow meter was used to measure heat flow through each specimen continuously for a period ranging from about 7 1/2 to 18 months for wet specimens and somewhat less for some of the dry ones. Heat flow rates were plotted against temperature difference using daily arithmetic averages in most cases; two-week averages were used in a few cases. For open-cell and fibrous insulations of 20 percent moisture content, heat flow rates exceeded rates for dry insulation by a factor of two or more. The data points were scattered. Inspection suggested that this was partly owing to moisture distribution, which affected the rate of heat flow at a given temperature difference. Measurements at the quarter points provided information about temperature gradients along the path of heat flow, and hence about moisture distribution in the insulation. These results suggested that moisture migrated to the upper layers in the wintertime, leaving the lower layers nearly dry. Ratios of heat flow in wet and dry specimens were in fairly good agreement with those obtained by other investigators., Proceedings of the Conference on Thermal Insulation, Materials and Systems for Energy Conservation in the 80's: 08 December 1981, Clearwater Beach, FL, USA

This paper is concerned with the thermal performance of blown Mineral Fibre Insulation (MFI), and more specifically with the question of how to ensure that the purchaser receives the amount of thermal resistance contracted for. It is shown that, owing to the variability of the material and installation techniques, two requirements must simultaneously be fulfilled at the time of installation: ( i) minimum installed thickness; and (ii) minimum mass per unit area. This Note deals with the determination of these minimum values, and the sample preparation and laboratory testing of the thermal resistance of MFI.

A test facility and procedures to determine the thermal characteristics of window products were developed. Initial work was conducted on the following types of glazing units: -- sealed double-glazed, clear glass.-- sealed double-glazed with low emissivity coating on clear glass -- sealed triple-glazed, clear glass -sealed triple-glazed with thin plastic film with low emissivity coating -- unsealed double-glazed without spacer. Overall heat transmission coefficients (U-value) are also provided. The experimental results of some of the specimens are compared with values predicted using the computer program VISION developed to evaluate the thermal performance of glazing systems.

With the growing emphasis on energy conservation, various codes and building authorities have raised the requirements for the thermal resistance of building envelopes. Although these requirements are related to a nominal level of performance, very little is said about the difference between material performance in-situ and estimates established by laboratory measurements. This review discusses how to develop appropriate test methods for evaluating the performance of thermal insulation under service conditions.

The total heat transfer through moist, porous building materials is the sum of a number of heat-transfer phenomena. This paper presents experimental data on heat transfer through specimens of moist aerated concrete and mineral fiberboard. The aerated concrete specimens with known initial moisture distributions were exposed to a temperature gradient. This temperature gradient caused a redistribution of moisture which in turn changed the heat flow through the material. The changes were monitored by means of thermal probes, heat flowmeters, and thermocouples. The results of measurements were compared with calculations based on a simplified analytical model and with measurements made by other investigators. A second series of tests was made on a moist specimen of high-density mineral fiberboard to demonstrate the extent of the dependence of the total thermal resistance on the distribution of moisture in the material., Thermal Transmission Measurements of Insulation : Symposium: 19 September 1977, Philadelphia, PA, USA

As in horizontal applications, the thickness and safety aspects of cellulose fibre insulation (CFI) also apply to wall applications. In the latter case, however, failure to allow for settlement will not decrease thickness but will leave uninsulated gaps at the tops of the stud spaces. As it is impossible to see the CFI flowing into the spaces, a good installation depends on proper machine adjustment and installation technique. This paper reports on the findings of a study conducted to determine the effects of application technique on installation quality.

This paper is a select and annotated bibliography dealing with the construction of heat flux transducers, their calibration and error verification, and the methods used for thermal resistance determination., Building Applications of Heat Flux Transducers: A Symposium, September 22, 1983, Philadelphia, Pennsylvania, United States

Heat flow meter and calorimeter measurements have been used in investigating factors that influence in situ thermal resistance measurements on wood frame walls: wall orientation, length of measurement period, thermal lag, mean temperature effects and time of measurement. They have also been used to determine the installed resistance of insulation and the effect of framing members on the resistance of the whole wall. Knowledge of the dynamic effects of a test wall is essential in obtaining accurate results. Accurate thermal resistance measurements were obtained for wood frame walls from 24 h integrated values of heat flow and temperature difference (appropriate adjustments were made for time lag and mean temperature effects). Other measurement strategies produced less accurate (but acceptable) or completely unacceptable results.

Users of cellulose fibre insulation (CFI) have two basic concerns: whether the insulation will provide the desired thermal resistance over the life of the building, and whether its use will constitute a health hazard or contribute to the deterioration of the building. Thermal resistance is primarily a function of thickness. CFI, however, is prone to settlement so the thickness will depend on the initial or blown density and the settled or design density. This note examines the precision of various methods used to determine design density. This is important in order to assist the contractor in determining the amount of CFI required for an installation and to ensure that the long term R-value of the CFI is as required.

L’objectif du présent travail est d’évaluer le potentiel agronomique de populations traditionnelles de luzernes originaires de 5 régions du Maroc : Ziz, Dra, Dades, Demnate et montagne. L’évaluation porte sur des caractères de production à diverses saisons, des indices de qualité et d’incidence des maladies. L’étude est menée en parcelles pendant deux années dans deux environnements différents, l’un en milieu "oasis" à Errachidia, l’autre dans le périmètre semi-aride du Tadla. Outre les populations locales, 2 variétés vulgarisées African et Moapa sont incluses dans les essais. Le rendement moyen par coupe est de 3,12 tMS/ha à Errachidia et 2,8 tMS/ha au Tadla. La plus grande variation entre populations et entre origines géographiques est observée pendant les périodes de moindre production : en été et surtout en hiver. Les populations de Demnate sont productives dans les 2 milieux, leur sensibilité au stress thermique et au mildiou est plus prononcée que celle des populations d’oasis. Les populations de montagne ont manifesté une faible adaptation aux 2 milieux, avec une faible production en hiver et une sensibilité à la verse. Les populations des oasis ont des comportements diversifiés en hiver et en pleine saison, les plus productives proviennent de l’aval des vallées désertiques et d’oasis isolées. En référence à la production totale fournie par les variétés vulgarisées, certaines populations traditionnelles se sont révélées d’un niveau comparable. Ce résultat, obtenu sur du matériel qui n’a pas subi de sélection artificielle, laisse présager un gain par son exploitation rapide dans les schémas de sélection., Two comparative trials have been done in order to evaluate alfalfa populations collected in Morocco. These populations originate from 5 geographic regions: Ziz, Dra, Dades, Demnate and "Mountains". "Mountains" includes sites of prospection of Alt Atlas. Evaluation has been done on productivity characteristics during all the seasons of exploitation. Quality indices and deseases effects have been estimated. Adaptative characteristics such winter dormancy and aestival growth have been studied in order to know the adaptability of the collected populations. Trials have been done in plots during two years and in two environments. The first environment &dquo;Errachidia&dquo; corresponds to an oasia climate, the second one &dquo;Tadla&dquo; corresponds to a semi arid climate. Two cultivars, well known in North Africa, African and Moapa have been included as controls. Dry matter mean yield per cut amount 3,12 t/ha at Errachidia and 2,8 t/ha at Tadla. The most important variability between populations and geographic origins is observed during seasons of lower productivity : winter and summer. Demnate populations show good productivity in the two environments. However they are more sensitive to high temperatures in summer and to mildiou disease than oasia populations. Mountains populations seem inadapted in the two environmental conditions of trials. They are sensitive to logging and they have a low winter productivity. The most productive oasia populations originate from desertic valleys and isolated oasia. A great range of variability have been observed for productivity and adaptability. Some methodological aspects of characterisation of forage crops populations are discussed. Compared to the two controls cultivars, some of the collected populations have the same yield. As this result is obtained on non selected populations, rapid genetic progress can be expected by selection.

In the fall of 1987 Suter Keller Inc. (SKI) was retained by the Ottawa-Carleton Regional Housing Authority to carry out an investigation of the deteriorating exterior loadbearing masonry walls at a building complex constructed in Ottawa in 1973-74. The main objectives of the work were to determine the cause or causes of deterioration and to propose remedial work options. SKI in turn engaged the services of the Institute for Research in Construction (IRC) to carry out physical testing of brick samples for a durability assessment, monitor moisture/temperature conditions of an exterior wall, and provide input into the overall assessment of building envelope deterioration., Proceedings of the Fifth Canadian Masonry Symposium: 05 June 1989, Victoria, B.C., Canada

Experimental flat roof systems were studied at an outdoor test facility. Heat flow rates and temperatures were measured with heat flow meters and thermocouples, and the values were recorded on magnetic tape at fixed intervals. The results were averaged over 24-h periods. Thermal resistances of systems and individual components were found using average net heat flow rates and temperature differences. Two analytical methods were used. In the first, the ratio of heat flow to temperature difference was calculated. This method was unreliable at low heat rates due to a bias in the results. In the second method, the slope of heat flow versus temperature difference was used as the basis for calculation. Thermal resistances of several pieces of insulation found by this method were compared with results obtained using laboratory equipment. The differences ranged from about 0.5 to 5 percent., Symposium on Thermal Insulation Performance: 22 October 1978, Tampa, FL, USA

This paper provides industrial laboratories with guidelines for verifying precision in thermal resistance determinations. It deals with both equipment and test procedures, and discusses the development of a calibration program for the heat flow meter (HFM) apparatus used in quality control of low-density mineral fiber insulations manufactured at the Innisfail Plant of Manville Canada Inc. To ensure agreement between the HFM apparatus used in the plant and the guarded hot plate (GHP) apparatus used by National Research Council of Canada, the following elements were incorporated in the calibration program: selection, fabrication and verification of low-density glass fiber reference systems, calibration of apparatus, error analysis of apparatus, maintenance of calibration., Thermal Conductivity Eighteen : Proceedings of the 18th International Thermal Conductivity Conference: 03 October 1983, Rapid City, SD, USA

During the service life of gas-filled cellular plastics ( GFCP), air diffuses into the foam cells and the gaseous blowing agent diffuses out, each at a rate that depends on the type of polymer and temperature. This process, which reduces the effectiveness of insulation, is known as aging. This paper presents a model for calculating the thermal resistance of the GFCP slab as a function of time. It incorporates the effect of phase changes (condensation and evaporation) in the gaseous blowing agent and the use of material characteristics (diffusion coefficient) varying in the cross-section of the GFCP slab. The results are compared with measurements., Also published in Improved Thermal Insulation : Problems and Perspectives

This paper presents a summary of an investigation of the precision and accuracy achievable with the NRCC 450 mm square GHP with a 300 mm main heater and a 75 mm guard ring heater and a 600 mm GHP with 300 mm main and a 150 mm guard ring heater. Only the uncertainties that may be attributed to the instrument are discussed here., Thermal Conductivity Seventeen : Proceedings of the 17th International Thermal Conductivity Conference: 15 June 1981, Gaithersburg, MD, USA

The authors calculate the heat gain weighting factors for lights in order to evaluate the load placed on air conditioning equipment. They determine these factors for lights recessed into a suspended ceiling beneath a reinforced concrete slab, examining two distinct cases: one in which the space between the ceiling and the slab is used for ventilation exhaust and the other where this space is unventilated. The calculated weighting factors seem to be lower than those published elsewhere, and the results appear to depend entirely on accepted heat transfer coefficient values.

The simple basic theory of natural convection across openings in vertical partitions has been generalized to include both heat and mass transfer. Experiments were carried out in a large heat-flow apparatus with openings from 3 to 12 in high and with air as the convecting fluid. Because of the high thermal resistance of the partition, the test results for the Nusselt number as a function of the Grashof number based on opening height in the range 10(6) less than Gr less than 10(8) would also be expected to be directly applicable to mass transfer.

A continuous record was kept at Ottawa, Ontario, of the heat flow from the ground into the snow-cover and temperatures in the ground, snow and air during the two winters 1955-56 and 1956-57. A correlation was found between the difference in the mean air temperature and the temperature 5 centimeters under the ground, the snow depth and the heat flux. Values were obtained for the effective thermal resistance of the snow cover under field conditions.

In cold weather, sealed double-glazing units experience thermal stresses that can lead to breakage of the inner pane. The potential for thermal breakage is related to the difference between the mean temperature and the edge temperature of the inner pane. Breakage potential is affected by features of the sealed unit itself, such as the thermal resistance of the glazed air space and of the edge spacer. In addition, the breakage potential is affected by the thermal characteristic of the window member in which the sealed unit is glazed, by the thermal characteristics of the glazing method, and by the configuration of the heating terminal unit. The effects of the above factors on the cold- weather breakage potential of sealed units were investigated in laboratory tests, and are herein reported.

Subcommittee 5.1 of ASTM Committee E-6 has been engaged for the past several years in developing a standard test for evaluating the condensation performance of windows. This activity has not yet resulted in an accepted standard method, but one method currently is being considered as a possible standard. The article outlines some of the considerations that are important in the development of such a standard test. It also describes work undertaken by the Division of Building Research, National Research Council of Canada, to evaluate the suitability of the test method.

Natural convection through square openings in a horizontal partition for the case of heavier fluid above the partition is investigated using air as the fluid medium. The test results relating the Nusselt number to the Grashof number and to the ratio of opening thickness to opening width are found to agree generally with the requirements of theory. Although the Prandtl number for air remained constant in all tests, it was nevertheless possible, with the help of the theory, to show the approximate influence to be expected for any value of the Prandtl number. Because of the high thermal resistance of the partition material the test results may also be expected to apply directly to mass transfer. The following range of variables was covered in the tests: Grashof number Gr(H) based on partition thickness and air temperature difference across the opening, 3 X 10(4) less than Gr(H) less than 4 X 10(7); ratio of partition thickness to the side of the square opening H/L, 0.0825 less than H/L less than 0.66, with openings of 6 X 6 in, 9 X 9 in and 12 X 12 in.