A mathematical model of quorum sensing regulated EPS production in biofilm communities

<p>Abstract</p> <p>Background</p> <p>Biofilms are microbial communities encased in a layer of extracellular polymeric substances (EPS). The EPS matrix provides several functional purposes for the biofilm, such as protecting bacteria from environmental stresses, and providing mechanical stability. Quorum sensing is a cell-cell communication mechanism used by several bacterial taxa to coordinate gene expression and behaviour in groups, based on population densities.</p> <p>Model</p> <p>We mathematically model quorum sensing and EPS production in a growing biofilm under various environmental conditions, to study how a developing biofilm impacts quorum sensing, and conversely, how a biofilm is affected by quorum sensing-regulated EPS production. We investigate circumstances when using quorum-sensing regulated EPS production is a beneficial strategy for biofilm cells.</p> <p>Results</p> <p>We find that biofilms that use quorum sensing to induce increased EPS production do not obtain the high cell populations of low-EPS producers, but can rapidly increase their volume to parallel high-EPS producers. Quorum sensing-induced EPS production allows a biofilm to switch behaviours, from a colonization mode (with an optimized growth rate), to a protection mode.</p> <p>Conclusions</p> <p>A biofilm will benefit from using quorum sensing-induced EPS production if bacteria cells have the objective of acquiring a thick, protective layer of EPS, or if they wish to clog their environment with biomass as a means of securing nutrient supply and outcompeting other colonies in the channel, of their own or a different species.</p

Inheriting texture maps between different complexity 3D meshes

3D digitisation has been applied in different application domains. Due to the continuous growing interest, commercial and experimental 3D acquisition systems have evolved. Nevertheless, there isn't an all-in-one solution, thus there is a need for combining different technologies in order to exploit the advantages of each approach. In this paper, we present a solution to a specific problem related to the combination of 3D data resulted from a non-colour laser triangulation scanner and a shape-fromsilhouette system. Our approach combines the data of these two 3D acquisition systems in order to produce a hybrid 3D mesh model with the geometric accuracy and detail captured by the laser scanner and the high resolution textural information of the shape-fromsilhouette system. We propose an algorithm that is based on virtual photo shooting and an inverse texture map projection phase. We present an example of our algorithm’s operation on exchanging the texture maps of a replica artefact which has been digitised by both systems

INVESTIGATING THE EFFECT OF FOCUS STACKING ON SFM-MVS ALGORITHMS

The Depth of Field (DoF) is a vital factor in photogrammetric applications. Its effect is in most cases pretty obvious especially when capturing small artefacts. It is very important to observe its behaviour as it affects the ability to capture all the details of an object. Focus stacking is a technique in computational photography, in which a set of images focused on different planes with limited DoF are combined in order to considerably extend the DoF. Today, there is a number of focus stacking methods that can be applied in order to produce a full-focus image. In this paper, we investigate the application and effects of focus stacking on SfM-MVS 3D reconstruction. Specifically, our experiment involves the 3D reconstruction of a selected artefact using both traditional all-focus photography and focus stacking. The artefact has already been digitised with a high accuracy and resolution structured light 3D scanner, and that 3D model served as the reference model, with which SfM models were compared. We discuss on these fist results and present some preliminary assessment on the application of focus stacking for the SfM-MVS-based 3D reconstruction

ENHANCING CLOSE-UP IMAGE BASED 3D DIGITISATION WITH FOCUS STACKING

The 3D digitisation of small artefacts is a very complicated procedure because of their complex morphological feature structures, concavities, rich decorations, high frequency of colour changes in texture, increased accuracy requirements etc. Image-based methods present a low cost, fast and effective alternative because laser scanning does not meet the accuracy requirements in general. A shallow Depth of Field (DoF) affects the image-based 3D reconstruction and especially the point matching procedure. This is visible not only in the total number of corresponding points but also in the resolution of the produced 3D model. The extension of the DoF is a very important task that should be incorporated in the data collection to attain a better quality of the image set and a better 3D model. An extension of the DoF can be achieved with many methods and especially with the use of the focus stacking technique. In this paper, the focus stacking technique was tested in a real-world experiment to digitise a museum artefact in 3D. The experiment conditions include the use of a full frame camera equipped with a normal lens (50mm), with the camera being placed close to the object. The artefact has already been digitised with a structured light system and that model served as the reference model in which 3D models were compared and the results were presented

3D object partial matching using panoramic views

In this paper, a methodology for 3D object partial matching and retrieval based on range image queries is presented. The proposed methodology addresses the retrieval of complete 3D objects based on artificially created range image queries which represent partial views. The core methodology relies upon Dense SIFT descriptors computed on panoramic views. Performance evaluation builds upon the standard measures and a challenging 3D pottery dataset originated from the Hampson Archeological Museum collection. © 2013 Springer-Verlag

Preservation of Architectural Heritage Through 3D Digitization

Continuity and relation to the past are inherent in human nature. The remains of the past constitute culture and cultural heritage. Preservation and dissemination of cultural heritage appear to be, nowadays, a universal priority. Historic/architectural monuments are among the most significant categories of cultural heritage and their 3D digitization appears to be a chief way towards that direction. 3D digitization of architectural heritage is a very specific problem in the digitization domain. Since size, budget and applicability are some of the most important factors in choosing an appropriate digitization method, and since there is not an all-in-one solution in digitization, this problem cannot be always addressed by using one technique. In this paper we review methods that are available for 3D digitization of architectural heritage and we present two case studies of real-world digitization projects involving monuments and urban areas