Firm-Network Characteristics and Economic Robustness to Natural Disasters

This article proposes a theoretical framework to investigate economic robustness to exogenous shocks such as natural disasters. It is based on a dynamic model that represents a regional economy as a network of production units through the disaggregation of sectorscale Input-Output tables. Results suggest that disaster-related output losses depend on direct losses heterogeneity and on the economic network structure. Two aggregate indexes, concentration and clustering, appear as important drivers of economic robustness, offering opportunities for robustness-enhancing strategies. Modern industrial organization seems to reduce short-term robustness in a trade-off against higher efficiency in normal times.Natural disasters, Economic impacts, Economic Network.

Max-plus-linear Systems for Manufacturing Systems: Modeling and Control

In this chapter, the dynamics of manufacturing systems is characterized through the occurrence of events such as parts entering or leaving machines. Furthermore, we assume that the relations between events are expressed by synchronizations (i.e., conditions of the form: for all k greater than or equal to l, occurrence k of event e2 is at least t units of time after occurrence k-l of event e1). Note that this assumption often holds when the considered manufacturing system is functioning under a predefined schedule. First, we discuss the modeling of such systems by linear statespace models in the (max;+)-algebra (due to this property, such systems are often called (max;+)-linear systems). Second, standard open-loop and closed-loop control structures for (max;+)-linear systems are recalled. These control structures lead to a trade-off between the rapidity of systems and their internal buffer sizes. Some techniques to influence this trade-off are presented

Max-Plus-Linear Systems for Modeling and Control of Manufacturing Problems

In this chapter, the dynamics of manufacturing systems is characterized through the occurrence of events such as parts entering or leaving machines. Furthermore, we assume that the relations between events are expressed by synchronizations (i.e., conditions of the form: for all k ≥ l, occurrence k of event e2 is at least τ units of time after occurrence k − l of event e1). Note that this assumption often holds when the considered manufacturing system is functioning under a predefined schedule. First, we discuss the modeling of such systems by linear state-space models in the (max,+)-algebra (due to this property, such systems are often called (max,+)-linear systems). Second, standard open-loop and closed-loop control structures for (max,+)-linear systems are recalled. These control structures lead to a trade-off between the rapidity of systems and their internal buffer sizes. Some techniques to influence this trade-off are presented

A Morphing Technique Applied to Lung Motions in Radiotherapy: Preliminary Results

Organ motion leads to dosimetric uncertainties during a patient’s treatment. Much work has been done to quantify the dosimetric effects of lung movement during radiation treatment. There is a particular need for a good description and prediction of organ motion. To describe lung motion more precisely, we have examined the possibility of using a computer technique: a morphing algorithm. Morphing is an iterative method which consists of blending one image into another image. To evaluate the use of morphing, Four Dimensions Computed Tomography (4DCT) acquisition of a patient was performed. The lungs were automatically segmented for different phases, and morphing was performed using the end-inspiration and the end-expiration phase scans only. Intermediate morphing files were compared with 4DCT intermediate images. The results showed good agreement between morphing images and 4DCT images: fewer than 2 % of the 512 by 256 voxels were wrongly classified as belonging/not belonging to a lung section. This paper presents preliminary results, and our morphing algorithm needs improvement. We can infer that morphing offers considerable advantages in terms of radiation protection of the patient during the diagnosis phase, handling of artifacts, definition of organ contours and description of organ motion

Model predictive control for discrete event systems with partial synchronization

In this paper, we consider discrete event systems divided in a main system and a secondary system such that the inner dynamics of each system is ruled by standard synchronizations and the interactions between both systems are expressed by partial synchronizations (i.e., event e2 can only occur when, not after, event e1 occurs) of events in the secondary system by events in the main system. The main contribution consists in adapting model predictive control, developed in the literature for (max,+)-linear systems, to the considered class of systems. This problem is solved under the condition that the performance of the main system is never degraded to improve the performance of the secondary system. Then, the optimal input is selected to respect the output reference and the remaining degrees of freedom are used to ensure just-in-time behavior. The unconstrained problem is solved in linear time with respect to the length of the prediction horizon

The Pen Duick Escarpment off Morocco: A promising biogeochemically active carbonate mound laboratory (MiCROSYSTEMS)

Carbonate mud mounds, found in marine environments from shallow- to deep-water settings, span from Proterozoic to recent times. During the past decades, numerous active venting fields were discovered in deep marine environments and became a subject of extensive study for marine scientists. Mound building seems to be a fundamental but still enigmatic strategy for life. Various arguments suggest that microorganisms are playing a major role in the reef development, mound formation and biodiversity. Therefore, it is important to evaluate the microbial mediated processes of carbonate precipitation.Cold-water coral reefs thriving on carbonate mounds were discovered in the late 1990’s off western Ireland. An exploratory cruise of RV Belgica in 2002 off Morocco has led to the discovery of apparently juvenile mounds in water depths of 500-600 m, topping a cliff - the Pen Duick escarpment - flanked by giant mud volcanoes. Subsequent cruises have confirmed the colonization by deep-water corals and have unveiled extensive fields of seep-related carbonate crusts in the off-reef regions. Long cores taken in 2004 indicate that the ‘Pen Duick’ mounds, in which microbial action was demonstrated by a strong emission of hydrogen sulphide, may be considered as giant biogeochemical reactors. The mound sediments were dated 2 kyrs B.P. at the surface and 20 kyrs B.P. in a depth of 6 mbsf.A 450 cm long gravity core, coming from one of these juvenile mounds, was sampled and analyzed for mineralogy, stable isotopes composition, geochemistry, and microbial communities. Most of the sediment consists of calcite (coccoliths), quartz and dolomite. At a depth of 4 mbsf, we found hardened nodule-like structures, embedded in grey mud containing cold-water coral pieces. The presence of 20-30% of dolomite, in the carbonate phase, suggests a microbial influence during mineral formation. Preliminary results of the pore water geochemistry indicate a reactive sulphate – methane interface at 3.8 mbsf. In this layer we focused our studies on the microbial communities, such as methanogens, methanotrophs and sulphate reducers. The trend of the d13C values in digenetic carbonate supports the assumption of microbial activity in this section of the core. In order to define the primary microbial community involved in carbonate precipitation, we did direct culturing, DNA isolation and PCR analysis of three functional genes, the a subunit (mcrA) of the methyl-coenzyme M reductase (MCR), the a subunit (pmoA) of the particulate methane monooxygenase (MMO) and the a and ß subunits (dsrA and dsrB, respectively) of the dissimilatory sulfite reductase (DSR). These enzymes are involved in methanogenesis, methanotrophy and sulphate reduction biochemical pathways, respectively. In summary, our initial results demonstrate that the Pen Duick carbonate mound can be considered as a natural laboratory in which to study cold-water coral ecosystems associated with microbial activity

Simulation of the deep-sea biosphere by a continuous high-pressure bioreactor

In ocean system Anaerobic Oxidation of Methane (AOM) followed by carbonate precipitation has a significant effect on the climate regulation, since this process avoids large methane emissions to the atmosphere and fixes carbon dioxide into carbonate structures. However the main difficulty to study AOM is that the consortia involved have extremely long doubling time (2-7 months) at ambient or low pressures. To simulate the in situ condition better and obtain a faster growth, we designed and constructed a unique continuous high-pressure bioreactor. The reactor can reach pressure up to 100 bars, representing a depth of 1000m below sea level; it can be operated in continuous or non-continuous style, simulating the different types of methane resource. By the help of this high pressure bioreactor system, we are also able to study the effect of environmental factors on AOM activity and on microbial community. Captain Arutyunov Mud Volcano (Gulf of Cadiz) sediment has been used as biomass resource and different molecular techniques (DGGE, cloning library, FISH) have been applied to examine the microbial community structure. By increasing methane partial pressure, an immediate increase of AOM activity has been observed before significant enrichment of biomass. A continuous methane flux is necessary to obtain optimal AOMactivity. Bacterial community is more sensitive to the change of pressure compared with archaeal community

Cours rationnel de dessin a l`usage des écoles élémentaires

I: Le dessin d`imitation. -- 3ème ed. -- 1880. -- 152 p.: il. n. II : Dessin d`ornement. -- 1878. -- VIII, 200 p. : il. n.Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201

Biogeochemistry and geomicrobiology of cold-water coral carbonate mounds - lessons learned from IODP Expedition 307

Large mound structures associated with cold-water coral ecosystems commonly occur on the slopes of continental margins, for instance, west of Ireland in the Porcupine Seabight, the Gulf of Cadiz or the Straits of Florida. In the Porcupine Seabight over 1500 mounds of up to 5 km in diameter and 250 m height lie at water depths of 600 to 900 m. The cold-water coral reef ecosystems associated with these structures are considered to be “hotspots” of organic carbon mineralization and microbial systems. To establish a depositional and biogeochemical/diagenetic model for cold-water carbonate mounds, Challenger Mound and adjacent continental slope sites were drilled in May 2005 during IODP Expedition 307. One major objective was to test whether deep sub-surface hydrocarbon flow and enhanced microbial activity within the mound structure was important in producing and stabilizing these sedimentary structures.Drilling results showed that the Challenger mound succession (IODP Site U1317) is 130 to 150 meters thick, and mainly consists of floatstone and rudstone facies formed of fine sediments and cold-water branching corals. Pronounced recurring cycles on the scales of several meters are recognized in carbonate content (up to 70% carbonate) and color reflectance, and are probably associated with Pleistocene glacial-interglacial cycles. A role for methane seepage and subsequent anaerobic oxidation was discounted both as a hard-round substrate for mound initiation and as a principal source of carbonate within the mound succession. A broad sulfate-methane transition (approximately 50 m thick) within the Miocene sediments suggested that the zone of anaerobic oxidation of methane principally occurs below the moundbase. In the mound sediments, interstitial water profiles of sulfate, alkalinity, Mg, and Sr suggested a tight coupling between carbonate diagenesis and low rates of microbial sulfate reduction. Overall organic carbon mineralization within cold-water coral mound appeared to be dominated by low rates of iron- and sulfate-reduction that occur in discrete layers within the mound. This was consistent with distributions of total cell-counts, acetate turnover (Webster et al. 2009) and hydrogenase activity (Soffiento et al. 2009). However, biomarker lipid distributions suggested that the Miocene sediments underlying the mound, into which sulfate is diffusing, as well as the sediments from the non-cold water coral reference site (U1318) contain higher abundances of living microbes. The results obtained from Expedition 307 are consistent with a picture emerging from other biogeochemical studies of cold-water coral mound and reef sites. Unless impacted by some external forcing (e.g. fluid flow or erosion event), the microbial activity in the underlying cold-water coral mound sediments is largely decoupled from the highly diverse, active surface ecosystem