904 research outputs found
Fotomodellazione e stereofotogrammetria per la creazione di modelli stratigrafici in archeologia dellâarchitettura
Architectural structures are 3D volumes and their features, which are recognized in the field through archaeological investigation (stratigraphic, metric and formal data), are distributed within the three-dimensions. Stratigraphic wall analysis normally needs front elevations or photo-mosaic images to draw the boundaries between each Stratigraphic Unit (SU). The Stratigraphic 3D component is not recorded because it is not taken into account by these supporting documents. With the support of photo-modelling and stereophotogrammetry, instead, it is possible to record the perimeter and volume of each SU in 3D space and also obtain isomorphic reproductions of the detected object. These copies are high quality photo-textured models that provide a complete overview of architectural volumes and the close dimensional framework (length, depth and width) of mouldings and decorative architectural elements. Moreover, the coordinates of any point can be extracted from these models in order to obtain traditional charts (maps, sections, elevations and axonometric views, useful to understand the process of installation of building elements). The purpose of this paper is to describe different techniques capable of acquiring 3D data of wall stratigraphy in order to define new methods of documentation based on the use of photo-modelling and stereophotogrammetry. The data used for this research refer to excavated sites or high-preserved fabrics of different ages and functions such as the late medieval bell-tower of the basilica of San Severo (Classe, Ravenna), the modern tower of Monte Erno (FC) and the church of San Bartolomeo in Tipano (FC). Starting with these cases, in this article we explore some of the technical aspects of data processing like speed, measurement accuracy, information content and equipment cost
Heterogeneity for IGF-II production maintained by public goods dynamics in neuroendocrine pancreatic cancer
The extensive intratumor heterogeneity revealed by sequencing cancer genomes is an essential determinant of tumor progression, diagnosis, and treatment. What maintains heterogeneity remains an open question because competition within a tumor leads to a strong selection for the fittest subclone. Cancer cells also cooperate by sharing molecules with paracrine effects, such as growth factors, and heterogeneity can be maintained if subclones depend on each other for survival. Without strict interdependence between subclones, however, nonproducer cells can free-ride on the growth factors produced by neighboring producer cells, a collective action problem known in game theory as the âtragedy of the commons,â which has been observed in microbial cell populations. Here, we report that similar dynamics occur in cancer cell populations. Neuroendocrine pancreatic cancer (insulinoma) cells that do not produce insulin-like growth factor II (IGF-II) grow slowly in pure cultures but have a proliferation advantage in mixed cultures, where they can use the IGF-II provided by producer cells. We show that, as predicted by evolutionary game theory, producer cells do not go extinct because IGF-II acts as a nonlinear public good, creating negative frequency-dependent selection that leads to a stable coexistence of the two cell types. Intratumor cell heterogeneity can therefore be maintained even without strict interdependence between cell subclones. Reducing the amount of growth factors available within a tumor may lead to a reduction in growth followed by a new equilibrium, which may explain relapse in therapies that target growth factors
Wave simulation for the design of an innovative quay wall: the case of Vlorë Harbour
Sea states and environmental conditions are basic data for the
design of marine structures. Hindcasted wave data have been applied here
with the aim of identifying the proper design conditions for an innovative
quay wall concept.
In this paper, the results of a computational fluid dynamics model are used to
optimise the new absorbing quay wall of Vlorë Harbour (Republic of
Albania) and define the design loads under extreme wave
conditions. The design wave states at the harbour entrance have been
estimated analysing 31Â years of hindcasted wave data simulated through the
application of WaveWatch III. Due to the particular geography and topography
of the Bay of Vlorë, wave conditions generated from the north-west are
transferred to the harbour entrance with the application of a 2-D spectral wave
module, whereas southern wave states, which are also the most critical for
the port structures, are defined by means of a wave generation model,
according to the available wind measurements. Finally, the identified extreme
events have been used, through the NewWave approach, as boundary conditions
for the numerical analysis of the interaction between the quay wall and the
extreme events. The results show that the proposed method, based on
numerical modelling at different scales from macro to meso and to micro,
allows for the identification of the best site-specific solutions, also for a
location devoid of any wave measurement. In this light, the objectives of
the paper are two-fold. First, they show the application of sea condition
estimations through the use of wave hindcasted data in order to properly
define the design wave conditions for a new harbour structure. Second, they
present a new approach for investigating an innovative absorbing quay wall based
on CFD modelling and the NewWave theory
Stable Heterogeneity for the Production of Diffusible Factors in Cell Populations
The production of diffusible molecules that promote survival and growth is common in bacterial and eukaryotic cell populations, and can be considered a form of cooperation between cells. While evolutionary game theory shows that producers and non-producers can coexist in well-mixed populations, there is no consensus on the possibility of a stable polymorphism in spatially structured populations where the effect of the diffusible molecule extends beyond one-step neighbours. I study the dynamics of biological public goods using an evolutionary game on a lattice, taking into account two assumptions that have not been considered simultaneously in existing models: that the benefit of the diffusible molecule is a non-linear function of its concentration, and that the molecule diffuses according to a decreasing gradient. Stable coexistence of producers and non-producers is observed when the benefit of the molecule is a sigmoid function of its concentration, while strictly diminishing returns lead to coexistence only for very specific parameters and linear benefits never lead to coexistence. The shape of the diffusion gradient is largely irrelevant and can be approximated by a step function. Since the effect of a biological molecule is generally a sigmoid function of its concentration (as described by the Hill equation), linear benefits or strictly diminishing returns are not an appropriate approximations for the study of biological public goods. A stable polymorphism of producers and non-producers is in line with the predictions of evolutionary game theory and likely to be common in cell populations
The Vehicle Routing Problem with Divisible Deliveries and Pickups
The vehicle routing problem with divisible deliveries and pickups is a new and interesting model within
reverse logistics. Each customer may have a pickup and delivery demand that have to be served with
capacitated vehicles. The pickup and the delivery quantities may be served, if beneficial, in two separate visits.
The model is placed in the context of other delivery and pickup problems and formulated as a mixed-integer
linear programming problem. In this paper, we study the savings that can be achieved by allowing the pickup
and delivery quantities to be served separately with respect to the case where the quantities have to be served
simultaneously. Both exact and heuristic results are analysed in depth for a better understanding of the problem
structure and an average estimation of the savings due to the possibility of serving pickup and delivery
quantities separately
Development of flood probability charts for urban drainage network in coastal areas through a simplified joint assessment approach
The operating conditions of urban drainage networks during storm events depend on the hydraulic conveying capacity of conduits and also on downstream boundary conditions. This is particularly true in coastal areas where the level of the receiving water body is directly or indirectly affected by tidal or wave effects. In such cases, not just different rainfall conditions (varying intensity and duration), but also different sea-levels and their effects on the network operation should be considered. This paper aims to study the behaviour of a seaside town storm sewer network, estimating the threshold condition for flooding and proposing a simplified method to assess the urban flooding severity as a function of climate variables. The case study is a portion of the drainage system of Rimini (Italy), implemented and numerically modelled by means of InfoWorks CS code. The hydraulic simulation of the sewerage system identified the percentage of nodes of the drainage system where flooding is expected to occur. Combining these percentages with both climate variables' values has lead to the definition of charts representing the combined degree of risk "rainfall-sea level" for the drainage system under investigation. A final comparison between such charts and the results obtained from a one-year rainfall-sea level time series has demonstrated the reliability of the analysis
CFD investigations of OXYFLUX device, an innovative wave pump technology for artificial downwelling of surface water
publisher: Elsevier articletitle: CFD investigations of OXYFLUX device, an innovative wave pump technology for artificial downwelling of surface water journaltitle: Applied Ocean Research articlelink: http://dx.doi.org/10.1016/j.apor.2016.10.002 content_type: article copyright: © 2016 Elsevier Ltd. All rights reserved
Anti-inflammatory treatments in calving dairy cows: effects on haematological and metabolic profiles
High yielding dairy cows are particularly vulnerable during the transition period to any event able to stimulate immune system. In contrast, response to these events is easily controlled in other stages of lactation
Cooperation among cancer cells: applying game theory to cancer
Cell cooperation promotes many of the hallmarks of cancer via the secretion of diffusible factors that can affect cancer cells or stromal cells in the tumour microenvironment. This cooperation cannot be explained simply as the collective action of cells for the benefit of the tumour because non-cooperative subclones can constantly invade and free-ride on the diffusible factors produced by the cooperative cells. A full understanding of cooperation among the cells of a tumour requires methods and concepts from evolutionary game theory, which has been used successfully in other areas of biology to understand similar problems but has been underutilized in cancer research. Game theory can provide insights into the stability of cooperation among cells in a tumour and into the design of potentially evolution-proof therapies that disrupt this cooperation
Evolutionary dynamics of tumor-stroma interactions in multiple myeloma
Cancer cells and stromal cells cooperate by exchanging diffusible factors that sustain tumor growth, a form of frequency-dependent selection that can be studied in the framework of evolutionary game theory. In the case of multiple myeloma, three types of cells (malignant plasma cells, osteoblasts and osteoclasts) exchange growth factors with different effects, and tumor-stroma interactions have been analysed using a model of cooperation with pairwise interactions. Here we show that a model in which growth factors have autocrine and paracrine effects on multiple cells, a more realistic assumption for tumor-stroma interactions, leads to different results, with implications for disease progression and treatment. In particular, the model reveals that reducing the number of malignant plasma cells below a critical threshold can lead to their extinction and thus to restore a healthy balance between osteoclast and osteoblast, a result in line with current therapies against multiple myeloma
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