The type VI secretion system (T6SS) is a nanomachine used by many bacteria to drive a toxin-laden needle into other bacterial cells. Although the potential to influence bacterial competition is ...clear, the fitness impacts of wielding a T6SS are not well understood. Here we present a new agent-based model that enables detailed study of the evolutionary costs and benefits of T6SS weaponry during competition with other bacteria. Our model identifies a key problem with the T6SS. Because of its short range, T6SS activity becomes self-limiting, as dead cells accumulate in its way, forming "corpse barriers" that block further attacks. However, further exploration with the model presented a solution to this problem: if injected toxins can quickly lyse target cells in addition to killing them, the T6SS becomes a more effective weapon. We tested this prediction with single-cell analysis of combat between T6SS-wielding Acinetobacter baylyi and T6SS-sensitive Escherichia coli. As predicted, delivery of lytic toxins is highly effective, whereas nonlytic toxins leave large patches of E. coli alive. We then analyzed hundreds of bacterial species using published genomic data, which suggest that the great majority of T6SS-wielding species do indeed use lytic toxins, indicative of a general principle underlying weapon evolution. Our work suggests that, in the T6SS, bacteria have evolved a disintegration weapon whose effectiveness often rests upon the ability to break up competitors. Understanding the evolutionary function of bacterial weapons can help in the design of probiotics that can both establish well and eliminate problem species.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Recent organizational theorizing contends that loosely structured fluid social collectives may attain degrees of “organizationality” depending on whether or not they achieve certain organization-like ...elements. The organizationality approach offers a compelling account for the persistence of fluid social collectives, but the framework could be strengthened by moving beyond language-centered explanations and including into theorizing a plurality of “entities” that differ in ontological status. Based on a case study within the context of a fluid user-built recreation space, this study adopts a relational ontology viewpoint on materiality to show how dynamic aspects of natural elements, expectations, feelings, and the cyclicality of nature can be theorized as material, and thus mattering, to organizing processes. Findings reveal that the degree of durability of these entities is key for understanding interconnected decision-making, identity, and ultimately how the fluid collective achieves or degrades organizationality.
Throughout their evolutionary history, bacteria have faced diverse threats from other microorganisms, including competing bacteria, bacteriophages and predators. In response to these threats, they ...have evolved sophisticated defence mechanisms that today also protect bacteria against antibiotics and other therapies. In this Review, we explore the protective strategies of bacteria, including the mechanisms, evolution and clinical implications of these ancient defences. We also review the countermeasures that attackers have evolved to overcome bacterial defences. We argue that understanding how bacteria defend themselves in nature is important for the development of new therapies and for minimizing resistance evolution.
The hybrid algorithm for chronic total occlusion (CTO) percutaneous coronary intervention (PCI) was developed to improve procedural outcomes. Large, prospective studies validating the algorithm in a ...broad multicenter setting with operators of different experience levels are lacking.
The RECHARGE (REgistry of Crossboss and Hybrid procedures in FrAnce, the NetheRlands, BelGium and UnitEd Kingdom) registry aims to report achievable results using the hybrid algorithm.
Between January 2014 and October 2015, consecutive patients undergoing hybrid CTO-PCI were prospectively enrolled in 17 centers. Procedural techniques, outcomes, and in-hospital complications were analyzed.
A total of 1,253 CTO-PCIs were performed in 1,177 patients, of which 86% were men. Mean age was 66 ± 11 years. The average Japanese CTO score was 2.0 ± 1.0, and was higher in the failure group (2.6 ± 0.6 vs. 1.9 ± 1.0; p < 0.001). Overall procedure success was 86% and major in-hospital complications occurred in 2.6%. Antegrade wire escalation was the preferred primary strategy in 77%, followed by retrograde (17%) and antegrade dissection re-entry strategies (7%). Primary strategies were successful in 60%. Consecutive strategies were applied in 34% and were successful in 74%. Antegrade dissection re-entry and retrograde strategies were the most common bailout strategies and were successful in 67% and 62%, respectively. Median procedure and fluoroscopy time were 90 (interquartile range IQR: 60 to 120) min and 35 (IQR: 21 to 55) min, contrast volume was 250 (IQR: 180 to 340) ml, and radiation doses (air kerma and dose area product) were 1.6 (IQR: 1.0 to 2.7) Gy and 98 (IQR: 57 to 168) Gy·cm
, respectively.
High procedure and patient success rates, combined with a low event rate and improved procedural characteristics, support further use of the hybrid algorithm for a broad community of appropriately trained CTO operators.
Height-from-Polarisation with Unknown Lighting or Albedo Smith, William A. P.; Ramamoorthi, Ravi; Tozza, Silvia
IEEE transactions on pattern analysis and machine intelligence,
2019-Dec.-1, 2019-Dec, 2019-12-1, 20191201, Letnik:
41, Številka:
12
Journal Article
Recenzirano
Odprti dostop
We present a method for estimating surface height directly from a single polarisation image simply by solving a large, sparse system of linear equations. To do so, we show how to express polarisation ...constraints as equations that are linear in the unknown height. The local ambiguity in the surface normal azimuth angle is resolved globally when the optimal surface height is reconstructed. Our method is applicable to dielectric objects exhibiting diffuse and specular reflectance, though lighting and albedo must be known. We relax this requirement by showing that either spatially varying albedo or illumination can be estimated from the polarisation image alone using nonlinear methods. In the case of illumination, the estimate can only be made up to a binary ambiguity which we show is a generalised Bas-relief transformation corresponding to the convex/concave ambiguity. We believe that our method is the first passive, monocular shape-from-x technique that enables well-posed height estimation with only a single, uncalibrated illumination condition. We present results on real world data, including in uncontrolled, outdoor illumination.
In this paper, we present a complete framework to inverse render faces with a 3D Morphable Model (3DMM). By decomposing the image formation process into geometric and photometric parts, we are able ...to state the problem as a multilinear system which can be solved accurately and efficiently. As we treat each contribution as independent, the objective function is convex in the parameters and a global solution is guaranteed. We start by recovering 3D shape using a novel algorithm which incorporates generalization error of the model obtained from empirical measurements. We then describe two methods to recover facial texture, diffuse lighting, specular reflectance, and camera properties from a single image. The methods make increasingly weak assumptions and can be solved in a linear fashion. We evaluate our findings on a publicly available database, where we are able to outperform an existing state-of-the-art algorithm. We demonstrate the usability of the recovered parameters in a recognition experiment conducted on the CMU-PIE database.
In this paper we show how to perform scene-level inverse rendering to recover shape, reflectance and lighting from a single, uncontrolled image using a fully convolutional neural network. The network ...takes an RGB image as input, regresses albedo, shadow and normal maps from which we infer least squares optimal spherical harmonic lighting coefficients. Our network is trained using large uncontrolled multiview and timelapse image collections without ground truth. By incorporating a differentiable renderer, our network can learn from self-supervision. Since the problem is ill-posed we introduce additional supervision. Our key insight is to perform offline multiview stereo (MVS) on images containing rich illumination variation. From the MVS pose and depth maps, we can cross project between overlapping views such that Siamese training can be used to ensure consistent estimation of photometric invariants. MVS depth also provides direct coarse supervision for normal map estimation. We believe this is the first attempt to use MVS supervision for learning inverse rendering. In addition, we learn a statistical natural illumination prior. We evaluate performance on inverse rendering, normal map estimation and intrinsic image decomposition benchmarks.
Towards a Complete 3D Morphable Model of the Human Head Ploumpis, Stylianos; Ververas, Evangelos; Sullivan, Eimear Oa ...
IEEE transactions on pattern analysis and machine intelligence,
11/2021, Letnik:
43, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Three-dimensional morphable models (3DMMs) are powerful statistical tools for representing the 3D shapes and textures of an object class. Here we present the most complete 3DMM of the human head to ...date that includes face, cranium, ears, eyes, teeth and tongue. To achieve this, we propose two methods for combining existing 3DMMs of different overlapping head parts: (i). use a regressor to complete missing parts of one model using the other, and (ii). use the Gaussian Process framework to blend covariance matrices from multiple models. Thus, we build a new combined face-and-head shape model that blends the variability and facial detail of an existing face model (the LSFM) with the full head modelling capability of an existing head model (the LYHM). Then we construct and fuse a highly-detailed ear model to extend the variation of the ear shape. Eye and eye region models are incorporated into the head model, along with basic models of the teeth, tongue and inner mouth cavity. The new model achieves state-of-the-art performance. We use our model to reconstruct full head representations from single, unconstrained images allowing us to parameterize craniofacial shape and texture, along with the ear shape, eye gaze and eye color.
Abstract
Despite the growing interest in predicting global and regional trends in vegetation productivity in response to a changing climate, changes in water constraint on vegetation productivity ...(i.e., water limitations on vegetation growth) remain poorly understood. Here we conduct a comprehensive evaluation of changes in water constraint on vegetation growth in the extratropical Northern Hemisphere between 1982 and 2015. We document a significant increase in vegetation water constraint over this period. Remarkably divergent trends were found with vegetation water deficit areas significantly expanding, and water surplus areas significantly shrinking. The increase in water constraints associated with water deficit was also consistent with a decreasing response time to water scarcity, suggesting a stronger susceptibility of vegetation to drought. We also observed shortened water surplus period for water surplus areas, suggesting a shortened exposure to water surplus associated with humid conditions. These observed changes were found to be attributable to trends in temperature, solar radiation, precipitation, and atmospheric CO
2
. Our findings highlight the need for a more explicit consideration of the influence of water constraints on regional and global vegetation under a warming climate.
Bacteria commonly live in dense and genetically diverse communities associated with surfaces. In these communities, competition for resources and space is intense, and yet we understand little of how ...this affects the spread of antibiotic-resistant strains. Here, we study interactions between antibiotic-resistant and susceptible strains using in vitro competition experiments in the opportunistic pathogen Pseudomonas aeruginosa and in silico simulations. Selection for intracellular resistance to streptomycin is very strong in colonies, such that resistance is favoured at very low antibiotic doses. In contrast, selection for extracellular resistance to carbenicillin is weak in colonies, and high doses of antibiotic are required to select for resistance. Manipulating the density and spatial structure of colonies reveals that this difference is partly explained by the fact that the local degradation of carbenicillin by β-lactamase-secreting cells protects neighbouring sensitive cells from carbenicillin. In addition, we discover a second unexpected effect: the inducible elongation of cells in response to carbenicillin allows sensitive cells to better compete for the rapidly growing colony edge. These combined effects mean that antibiotic treatment can select against antibiotic-resistant strains, raising the possibility of treatment regimes that suppress sensitive strains while limiting the rise of antibiotic resistance. We argue that the detailed study of bacterial interactions will be fundamental to understanding and overcoming antibiotic resistance.
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