259 research outputs found

    Specialization and Technology in Mexico: A Virtual Pattern of Development and Competitiveness?

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    By the end of the 80s and the beginning of the 90s, Mexico has shown important transformations in its pattern of industrialization and competitiveness. It is hard to determine whether this pattern might become a successful one in the near future. However, some points about the features which are presently prevailing can be emphasized: (1) The structural change in the composition of Mexican exports and the improved performance in competitiveness when the dynamics in market shares are considered. This pattern is mainly related to again in competitiveness which is supported by what has been defined in terms of static allocative efficiency. Still, when actual competitiveness is analyzed, domestic industry appears to maintain the traditional structure which emerged during the ISI period. In a sense, sectors and firms that developed technical capabilities and economies of scale in this period possess higher opportunities to achieve actual competitiveness. (2) The specificity of this pattern seems to support the hypothesis that the new Mexican specialization has not been followed by a change in both the development of production capacity and technological capabilities. Moreover, when the analysis is extended in the most recent years, it seems to confirm how the maquila industry is one of the leading actors in industrial modernization. The diffusion of this type of industry introduces only very weak linkages with domestic productive sectors, strengthening the specificities of the competitiveness pattern in terms of production capacity and technological capabilities

    The Nature of Technological Change and Its Main Implications on National and Local Systems of Innovation

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    This paper aims at providing a survey (by no means exhaustive) of evolutionary theorizing, where by this we mean all the contributions which possess the methodological building blocks of an evolutionary theory, which this approach identifies as the consideration of dynamics, the presence of microfounded theories, the assumption of bounded rationality and of heterogeneity among agents, the recognition of the continuous appearance of novelty, the view of collective interactions as selection mechanisms, and finally the consideration of aggregate phenomena as emergent properties with nonstable nature. Along this path through the linkages from the micro technological studies to a broad aggregate system, we propose a concept and representation of Innovation Systems -national, regional, sectoral and at the micro levels- whereby their main feature will be related to capture empirically some pieces of the evolutionary approach

    Vicious circles in contracts and in logic

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    Contracts are formal promises on the future interactions of participants, which describe the causal dependencies among their actions. An inherent feature of contracts is that such dependencies may be circular: for instance, a buyer promises to pay for an item if the seller promises to ship it, and vice versa. We establish a bridge between two formal models for contracts, one based on games over event structures, and the other one on Propositional Contract Logic. In particular, we show that winning strategies in the game-theoretic model correspond to proofs in the logi

    Three decades of volume change of a small greenlandic glacier using ground penetrating radar, structure from motion, and aerial photogrammetry

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    Glaciers in the Arctic are losing mass at an increasing rate. Here we use surface topography derived from Structure from Motion (SfM) and ice volume from ground penetrating radar (GPR) to describe the 2014 state of Aqqutikitsoq glacier (2.85 km2) on Greenland's west coast. A photogrammetrically derived 1985 digital elevation model (DEM) was subtracted from a 2014 DEM obtained using land-based SfM to calculate geodetic glacier mass balance. Furthermore, a detailed 2014 ground penetrating radar survey was performed to assess ice volume. From 1985 to 2014, the glacier has lost 49.8 ± 9.4 106 m3 of ice, corresponding to roughly a quarter of its 1985 volume (148.6 ± 47.6 106 m3) and a thinning rate of 0.60 ± 0.11 m a-1. The computations are challenged by a relatively large fraction of the 1985 DEM (∼50% of the glacier surface) being deemed unreliable owing to low contrast (snow cover) in the 1985 aerial photography. To address this issue, surface elevation in low contrast areas was measured manually at point locations and interpolated using a universal kriging approach. We conclude that ground-based SfM is well suited to establish high-quality DEMs of smaller glaciers. Provided favorable topography, the approach constitutes a viable alternative where the use of drones is not possible. Our investigations constitute the first glacier on Greenland's west coast where ice volume was determined and volume change calculated. The glacier's thinning rate is comparable to, for example, the Swiss Alps and underlines that arctic glaciers are subject to fast changes

    Spatial variability in sea-ice algal biomass: an under-ice remote sensing perspective

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    Sea-ice algae are a paramount feature of polar marine ecosystems and ice algal standing stocks are characterized by a high spatio-temporal variability. Traditional sampling techniques, e.g., ice coring, are labor intensive, spatially limited and invasive, thereby limiting our understanding of ice algal biomass variability patterns. This has consequences for quantifying ice-associated algal biomass distribution, primary production, and detecting responses to changing environmental conditions. Close-range under-ice optical remote sensing techniques have emerged as a capable alternative providing non-invasive estimates of ice algal biomass and its spatial variability. In this review we first summarize observational studies, using both classical and new methods that aim to capture biomass variability at multiple spatial scales and identify the environmental drivers. We introduce the complex multi-disciplinary nature of under-ice spectral radiation profiling techniques and discuss relevant concepts of sea-ice radiative transfer and bio-optics. In addition, we tabulate and discuss advances and limitations of different statistical approaches used to correlate biomass and under-ice light spectral composition. We also explore theoretical and technical aspects of using Unmanned Underwater Vehicles (UUV), and Hyperspectral Imaging (HI) technology in an under-ice remote sensing context. The review concludes with an outlook and way forward to combine platforms and optical sensors to quantify ice algal spatial variability and establish relationships with its environmental drivers

    Session Types with Linearity in Haskell

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    Type systems with parametric polymorphism can encode a significant pro- portion of the information contained in session types. This allows concurrent programming with session-type-like guarantees in languages like ML and Java. However, statically enforcing the linearity properties of session types, in a way that is also natural to program with, is more challenging. Haskell provides various language features that can capture concurrent programming with session types, with full linearity invariants and in a mostly idiomatic style. This chapter overviews various approaches in the literature for session typed programming in Haskell. As a starting point, we use polymorphic types and simple type-level functions to provide session-typed communication in Haskell without linearity. We then overview and compare the varying approaches to implementing session types with static linearity checks. We conclude with a discussion of the remaining open problems. The code associated with this chapter can be found at http://github. com/dorchard/betty-book-haskell-sessions

    Microsatellite instability in gastric cancer is associated with tumor location and family history in a high-risk population from Tuscany

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    We studied the presence of microsatellite instability (MSI) in a series of 108 gastric cancers (GCs) previously identified in an epidemiological study carried out in a high-risk area around Florence, To investigate associations between MSI and GC family history, 34 cases (31.5%) who had a GC-affected first-degree relative were included in the series, A family history positive for colorectal cancer was reported quite rarely (5.6%). The analysis of 6 microsatellite loci in DNA from paired normal tissue and tumor samples microdissected from paraffin-embedded specimens revealed varying degrees of instability: 56 cases (51.8%) did not show instability at any of the 6 loci; 19 (17.6%) showed instability at 1 locus; 16 (14.8%) showed instability at 2 loci; 11 (10.2%) showed instability at 3 loci; 4 (3.7%) showed instability at 4 loci; and 2 (1.9%) showed instability at 5 loci, The replication error-positive (RER+) phenotype, defined as the presence of MSI at 2 or more loci, had a frequency of 30.6% (33 of 108) and tended to be positively associated with female sex, intestinal histological type, advanced tumor stage, vascular invasion, positive GC family history, and blood group of A type, No correlation emerged between age at diagnosis and RER+ phenotype, whereas a significant association with the RER+ phenotype was shown by the antral location. A multivariate analysis adjusting for a selected group of potential confounding factors confirmed the strong association of the RER+ phenotype with the antral location (P = 0.001) and with a positive GC family history (P < 0.05). Survival analyses at 5 and 8 years showed no difference between RER+ and RER-patients, even when corrected for stage distribution. By the microdissection technique, we also used microsatellite allele patterns to investigate intratumoral heterogeneity and genetic relationships between tumors and adjacent dysplasia and/or intestinal metaplasia. Areas of metaplasia and dysplasia demonstrated MSI only in cases with MSI-positive tumors, In MSI-positive tumors, there was consistent evidence of intratumoral microsatellite allele heterogeneity, indicating the presence of genetically divergent tumor cell clones within the same neoplasm
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