An air-drying model for piled logs of Eucalyptus globulus and Eucalyptus nitens in Chile

Artículo de publicación ISIBackground: Water accounts for around half of the total mass in living trees, and therefore large savings can be achieved if logs are dried before transporting or burning. Methods: An air-drying model for piled logs of Eucalyptus globulus Labill. and Eucalyptus nitens H.Deane & Maiden was developed. Daily moisture content (MC) loss was modelled based on meteorological variables and pile characteristics. The trial had a factorial design with two species, two debarking treatments (with or without bark) and two log lengths (244 and 350 cm). Independent trials started in July 2007 (winter), October 2007 (spring) and January 2008 (summer). There were five replicate piles per season and treatment. Wood pile masses were weighted weekly or twice weekly using a crane, a 10,000 kg balance and chains to hold the piles. Results: The main and interactive effects of seasons and treatments on daily MC loss were highly significant. However, the effect of season (climate) was far greater than the main effects of treatments or the season × treatment interaction. Overall, E. globulus dried 20 % faster than E. nitens, debarked logs dried 8 % faster than barked logs and 244 cm logs dried 3 % faster than 350 cm logs. Daily MC loss for the current day was better explained by a power function of MC at the start of the day, daily air relative humidity, daily air temperature and the number of logs per square metre of pile cross-section (or an equivalent average log diameter). Conclusions: The air-drying model for piled logs can be used to predict drying times (days) to achieve a given target moisture content, providing a new tool for decision-making in forest transport and industrial planning.Forestal Mininco S.A

Early Initiation of Highly Active Antiretroviral Therapies (HAART) for HIV/aids: The Contribution of a Stochastic Dynamic Model of Choice

Criteria for initiation of highly active antiretroviral treatments (HAART) in HIV-infected patients remain a matter of debate world-wide because short-term benefits have to be balanced with costs of these therapies, and restrictions placed on future treatment options if resistant viral strains develop. In order to take into account irreversibility and inertia effects associated with ex ante choices, we propose a simple stochastic dynamic model of sequential therapeutic choice with intermediary revelation of information, in which the efficiency gains from a new effective Therapy in second period are conditional on the results of the treatment in the previous period. We find that identical patients may be administered different treatments at the optimum; for parameters implying an all or nothing cut decision in period 2, a more forward looking decision rule is required in period 1 because there will be little space for adjustment to its consequences. Another finding is that as soon as risks of resistance due to therapeutic failure of initial treatments are significant, as perhaps in developing countries and in marginalized groups of developed countries, differences in the estimation of this risk should not influence the optimal decision about the size of the HIV-infected population eligible for early antiretroviral Therapy. The decision should then be based on pure efficiency/cost considerations. Le bien-fondé d'administrer précocement des traitements antirétroviraux à haute activité (HAART) aux personnes infectées par le VIH reste l'objet de débats dans le monde car leurs bienfaits à court terme peuvent compromettre les traitements futurs si des souches résistantes du virus se développent. Nous formulons un modèle qui combine irréversibilité et inertie dans un cadre de décision thérapeutique séquentielle. L'information se révèle entre la première et la deuxième période, si bien que la décision thérapeutique de deuxième période est conditionnelle à cette information. Il s'avère que des patients identiques peuvent se voir administrer des traitements différents à l'optimum; de plus, pour des paramètres justifiant des décisions bien tranchées en période 2 (à patients identiques traitement identique), la décision de période 1 est plus complexe car il est alors trop tard pour en renverser les conséquences en période 2. Autre résultat: supposons que le risque de résistance est élevé en cas d'échec thérapeutique du traitement initial (pays en développement; groupes défavorisés); nous montrons alors que les différences dans l'estimation de ce risque n'interviennent pas dans le choix optimal de la taille de la population qui se voit administrer le traitement antirétroviral. L'introduction du traitement relève alors purement de considérations d'efficacité et de coût.therapeutic decisions, uncertainty, information, irreversibility, treatment, learning, errors, décisions thérapeutiques, incertitude,information, irréversibilité, traitement, apprentissage, erreurs

Early Initiation of Highly Active Antiretroviral Therapies for Aids: Dynamic choice with Endogenous and Exogenous Learning

Criteria for initiation of highly active antiretroviral treatments (HAART) in HIV-infected patients remain a matter of debate world-wide because short-term benefits have to be balanced with costs of these therapies, and restrictions placed on future treatment options if resistant viral strains develop. On the other hand, postponing the introduction of HAART may involve a therapeutic opportunity cost if a patient’s health is allowed to deteriorate to such an extent of becoming unable to benefit from new treatments currently under development when they become available. We introduce a two period model where period one treatment adoption is an irreversible act with future, but uncertain, consequences. New information, both endogenous and exogenous, arises over time and shapes the conditions surrounding the second period therapeutic decision. A surprising result is that, under conditions that appear close to those surrounding the HAART debate, the magnitude of the feared resistance effect has no effect on leaves the optimal treatment decision as far as it is high enough. Le bien-fondé d’administrer précocement des traitements antirétroviraux à haute activité (HAART) aux personnes infectées par le VIH reste objet de débats dans le monde, car leurs bienfaits à court terme peuvent compromettre les traitements futurs si se développent des souches résistantes du virus. Par ailleurs retarder le recours aux HAART comporte un coût d’opportunité thérapeutique si la santé du patient se dégrade au point qu’il ne peut plus bénéficier par la suite des traitements encore en cours de développement. Nous formulons un modèle à deux périodes où l’adoption du traitement de première période est irréversible et engage le futur, alors que des informations et connaissances nouvelles, exogènes et endogènes, déterminent les conditions entourant la décision thérapeutique de deuxième période. Paradoxalement, sous des conditions reflétant bien les enjeux du recours aux HAART, il s’avère que l’effet résistance éventuel a d’autant moins de chance d’importer pour la décision optimale, que sa gravité est élevée.therapeutic decisions, uncertainty, information, irreversibility, treatment, endogenous learning, exogenous learning, décisions thérapeutiques, incertitude, information, irréversibilité, traitement, apprentissage endogène, apprentissage exogène

The mining industry in Canada north of the 55th parallel : a maritime traffic generator?

This paper reviews and assesses the state of the mining industry in Canada north of the 55th parallel. It aims to describe and monitor to what extent the development of mining projects in the Canadian Arctic are likely to trigger and expand commercial shipping in Canadian Arctic waters. Based on a literature and statistical review of publicly available information, the results show that only 3 actives mines out of 10 rely on a shipping logistics through Canadian Arctic waters to export raw materials. Once active and in operation, seven other mining projects will likely increase commercial shipping activities through Canadian Arctic waters, while it remains difficult to quantify precisely. However, this paper argues that the viability of northern mineral development is related to a wide variety of conditions including access to capital and foreign direct investment for the development and construction of infrastructure, international market conditions, and shifting demand which largely determines commodity prices and the profitability of a project, harsh environmental conditions, and high operating costs in northern latitudes. In this context, there is no Arctic mining rush and all these factors contribute to increasing the cost of doing business in the north

Fracturas en madera de Eucalyptus nitens: Efecto de las propiedades mecánicas a nivel ultraestructural y de la anatomía celular

Se realizó un estudio para indagar en las causas y posibles factores que originan la fractura en la estructura de la madera de Eucalyptus nitens. Para esto se examinó el comportamiento nanomecánico de la lamela media (LM), de las capas S1 y S2 de la pared celular. También se determinaron el número, área y diámetro de los vasos que están asociados a niveles de agrietamiento extremos (alto y bajo). Se estudiaron dos familias de Eucalyptus nitens procedentes de dos sitios de la 8va Región de Chile. Mediante el cálculo y análisis de la razón de ductilidad (E/H), se determinó que la LM es más quebradiza que la capa S1, y ésta a su vez más quebradiza que la capa S2; existiendo diferencias significativas en la ductilidad de estas capas. La LM y capa S1 se comportan como materiales resilientes, no así la capa S2. La diferencia en el módulo de resiliencia se relacionó con las mayores tensiones de corte que se presentaron en las interfaces LM/S2 y S1/S2. La caracterización de los vasos mostró que la familia con nivel de agrietamiento mayor, tiene mayor frecuencia, área y diámetro de vasos, los cuales contribuyen a la concentración de esfuerzos en la estructura celular de la madera. Los resultados evidenciaron que la capa S1 fue más débil que la capa S2 y LM dada la diferencia en resistencia entre ellas y que complementado con las tensiones internas que se generan en el proceso de crecimiento del árbol se producen las microgrietas. AbstractThis study was conducted to investigate the causes and posibles factors related to fractures in the cellular structure in Eucalyptus nitens. Nanomechanical cell wall properties at the middle lamella level (ML), S1 and S2 layers were evaluated. In addition, the area, and diameter of vessels were measured. These parameters were associated with extreme levels of cracking (high and low) in two Eucalyptus nitens families. e samples were taked from two sites of the 8th Region of Chile. The analysis of the ductility ratio (E/H) demonstrated that the ML is more brittle than the S1 layer; and the S1 is more brittle than S2 layer. The ML and S1 layer behave like resilient materials, but not the S2 layer. The diffrence in the modulus of resilience was related to higher shear stresses at the ML/S2 and at S1/S2 interfaces. The characterization of the vessels showed that the families with greater level of cracking have also lower frequency and greater area and diameter of vessels e S1 layer was weaker tan S2 layer and LM due to their difference in resistance between them and combined with the internal stresses might propagate the microcracks

Caracterización de propiedades mecánicas para segregar familias de Eucalyptus nitens por Nanoindentación en relación al grado de agrietamiento de las trozas

Seis familias de Eucalyptus nitens provenientes de dos suelos, arcilloso y trumao, localizados en la 8va Región de Chile, fueron estudiadas para seleccionar aquellas familias con menor grado de agrietamiento. Serelacionaron parámetros de agrietamiento evaluados a mesoescala con las propiedades nanomecánicas en un elemento de volumen representativo de estos árboles. Para segregar las familias se analizó el porcentaje deárea de grietas de estos árboles junto a la razón de ductilidad (E/H) obtenidos del módulo de elasticidad (E) y dureza (H) mediante la técnica de nanoindentación y el módulo de resiliencia (ur) ambos en la lamela media y capa S2 de la pared celular. Además, se determinó la diferencia entre el módulo de resiliencia entre la lamela media y la capa S2 (Δur), como un indicador de la tensión interfacial que induce fracturas principalmente en la capa S1 de la estructura celular de la madera. La nanocaracterización permitió establecer que la lamela media es más débil y susceptible a generar microgrietas que se propagan hasta ser visibles formando grietas mayores. El parámetro Δur entre la lamela media y capa S2 mostró ser menor en las familias 2 y 5. Estas familias presentaron menores niveles de tensión de corte en la interface de la capa S2-lamela media, por lo tanto, la cantidad de microgrietas, existiendo una buena relación con el porcentaje de grietas medidos en las familias de Eucalyptus nitens. De acuerdo a esto, las familias segregadas con bajo grado de tensión interfacial a nivel celular y bajo nivel de agrietamiento a mesoescala, fueron las familia 2 y 5.Six Eucalyptus nitens families from two soils in the 8th Region of Chile, clay and trumao, were studied to select families with lower degree of cracking. Cracking parameters evaluated at mesoscale, next tonanomechanical properties of the celular structure, were related in a representative volumen element of these tree, such as percentage of cracked area of trees relating them to the ductility ratio (E/H) obtained ofvalues of modulus of elasticity (E) and hardness (H) by nanoindentation and the modulus of resilience (ur) of the middle lamella and S2-layer of the cell wall were analyzed. Furthermore, it was determined that thedifference between the modulus of resilience (Δur) of the middle lamella with the S2-layer is a good indicator of the interfacial stress inducing fractures in the S1-layer. Using nanocharacterization it was established thatthe middle lamella is more brittle and susceptible to generate microcracks that spread to meso scale. The Δur between the middle lamella and S2 layer shown to be lower in families 2 and 5. These families showed to havelower levels of shear stress at the interface between the middle lamella and S2-layer, therefore the amount of microcracks that occur is lower, there is a good relationship with the percentage of measured cracks inthese families of Eucalyptus nitens. According these findings, the families that show low degree of interfacial tensión at celular level and low cracks index were family 2 and family 5

Efecto de la tasa de compresión en la morfología de grietas de debobinado para chapas de Eucalyptus nitens

El objetivo de este estudio fue evaluar el efecto de tres tasas de compresión (TC) en la morfología de grietas de debobinado en chapas de Eucalyptus nitens para la fabricación de tableros contrachapados. Chapas secas se obtuvieron desde un proceso de debobinado, con 1.8 mm de espesor a tres tasas de compresión TC1=0.5 %; TC2=3.5 % y TC3=5 %, las que se consiguieron ajustando la barra de presión y el cuchillo del torno debobinador marca Cremona de una planta de contrachapados del sur de Chile. Se obtuvieron probetas en forma aleatoria de los tres tipos de chapas procesadas. Fotografías fueron tomadas en el espesor de las chapas para el posterior procesamiento de imágenes. En el análisis morfológico de las grietas se evalúo: largo, área y frecuencia en las probetas para las tres tasas de compresión estudiadas. El análisis morfológico de imágenes mostró que existe una disminución del largo y profundidad de las grietas, así como también del área de grietas, cuando se aumenta la tasa de compresión. Diferencias significativas fueron halladas entre los niveles 0.5 % y 5 % de tasa de compresión. Esto implica que al aumentar la tasa de compresión, a través de un ajuste que involucra una menor distancia entre la barra de presión y el cuchillo debobinador, se obtienen chapas de mejor calidad, más rígidas y con una reducción del agrietamiento superficial en el tablero final. Abstract The objective of this study was to evaluate the effect of three nose bar pressure (TC) in the morphology of the lathe checks in Eucalyptus nitens veneers for the manufacture of plywood. Dried veneers were obtained from a peeling process, 1.8 mm thick three nose bar pressure TC1= 0.5%, TC2andTC3= 3.5%= 5%, which were obtained by adjusting the pressure bar and peeling knife of Cremona the in a plywood plant in southern Chile. Samples were obtained randomly from the three types of veneers processed. Photographs were taken in the veneer thickness for subsequent image processing. In the morphological analysis of the cracks was evaluated: length, area and frequency in the samples for the three nose bar pressure studied. Morphological analysis of images showed that a decrease in the length and depth of the lathe check, as well as the area, when the nose bar pressure increases. Significant differences were found between 0.5%and 5%levels of nose bar pressure. This implies that increasing the nose bar pressure, through a setting that involves a smaller distance between the pressure bar and peeling knife, you get better quality veneers, more rigid and with a reduction of surface cracking in the final plywood

Caracterización nanomecánica de la estructura celular y anatómica de Eucalyptus nitens y su relación con la frecuencia de grietas y rajaduras en madera redonda

El objetivo de este trabajo fue localizar el mínimo volumen en árboles de E. nitens que caracterice el comportamiento mecánico y anatómico para un muestreo no destructivo. Los árboles fueron cortados desde Mulchén y Yungay en la región del Bío-Bío. Se establecieron relaciones entre las propiedades nanomecánicas y la anatomía de la madera con el agrietamiento y las fracturas mayores (rajaduras). Se obtuvieron los parámetros razón de ductilidad (E/H) y módulo de resiliencia (ur), medidos en la capa S2 y lamela media. Los resultados mostraron que el volumen representativo de los árboles de E. nitens se encontraban a 3 metros de altura desde la base de los árboles y desde el anillo 5 al 7. Al mismo tiempo, se logró establecer que la lamela media es más frágil que la capa S2 de la pared celular. Se determinó una relación entre la caracterización de los vasos y el nivel de agrietamiento de la madera. Esto es, a mayor área y diámetro de los vasos y a menor número de éstos, el nivel de agrietamiento fue mayor. Las grietas se concentraron principalmente en los primeros metros de altura del árbol, existiendo una buena relación con el E/H de la lamela media, que mostró un cambio significativo a los 3 metros de altura. Las grietas en los anillos de crecimiento se centraron notoriamente en madera de temprana y en los anillos del 5 al 7 (desde médula a corteza). AbstractThe aim of this study was to define the minimum volumen in trees of E. nitens that characterize the mechanical and anatomy behavior for non-destructive sampling. The trees were cut from sites located in Mulchen and Yungay in the region of Bío Bío. Relationships were found between nano-mechanical properties, wood anatomy and wood cracks and fractures. The response variables were the ductility ratio (E/H) and the modulus of resilience (ur), in the S2 layer and middle lamella. The results showed that the representative volume, from E. nitens families is at 3 meter high from base of the trees and between the 5th to 7th annual rings. Also, it was established that the middle lamella is more brittle than the S2 layer. Relationship between the vessels morphology and the level of the wood cracking was observed. A high area of vessels, a high vessel diameter and a small frequency of them, resulted in high cracking. The cracks were mainly concentrated in the first meters of tree, were we found a good relationship of this response variable with the E/H ratio for the middle lamella; there was a significant change of this ratio at 3 meters high. Cracks were evident on earlywood and from the 5th to the 7th annual rings

Arctic routes opening up : strategies and perceptions of the bulk shipping industry

La fonte des glaces arctiques a suscité un intérêt renouvelé pour les routes arctiques dans les milieux de la recherche et dans les média. Plusieurs travaux se sont intéressés au secteur du conteneur, mais peu abordent spécifiquement le secteur du vrac. Une enquête auprès de plusieurs transporteurs maritimes du secteur du vrac, menée en 2010 puis en 2015, a cependant permis de souligner le faible intérêt des entreprises de ce marché pour le transit arctique.The melting of Arctic sea ice has sparked a renewed interest for Arctic routes in the research community and in the media. Several studies have focused on the container sector, but few specifically addressed the bulk sector. A survey of several bulk shipping companies, conducted in 2010 and 2015, however, highlighted the low interest of companies in this market for Arctic transi

Réalisation d’un Contrat d’Etudes Prospectives des secteurs du transport: Rapport final

Le CEP a pour objectif de réaliser un état des lieux du secteur, de conduire une analyse prospective qualitative et quantitative de l’évolution des métiers et des besoins de compétences du transport et de préconiser un plan d’actions pour les transports routiers, maritimes et fluviaux. A l’issue des travaux d’étude, le rapport final a été remis aux membres du Comité de pilotage (Ministère de l’emploi - DGEFP, Représentants des branches des transports, l’OPCA Transports et Services, Pôle Emploi, Ministère de l’écologie et du développement durable, des transport et du logement)