No abstract

The evolution of antibiotic resistance among bacteria threatens our continued ability to treat infectious diseases. The need for sustainable strategies to cure bacterial infections has never been greater. So far, all attempts to restore susceptibility after resistance has arisen have been unsuccessful, including restrictions on prescribing [1] and antibiotic cycling [2], [3]. Part of the problem may be that those efforts have implemented different classes of unrelated antibiotics, and relied on removal of resistance by random loss of resistance genes from bacterial populations (drift). Here, we show that alternating structurally similar antibiotics can restore susceptibility to antibiotics after resistance has evolved. We found that the resistance phenotypes conferred by variant alleles of the resistance gene encoding the TEM β-lactamase (bla TEM) varied greatly among 15 different β-lactam antibiotics. We captured those differences by characterizing complete adaptive landscapes for the resistance alleles bla TEM-50 and bla TEM-85, each of which differs from its ancestor bla TEM-1 by four mutations. We identified pathways through those landscapes where selection for increased resistance moved in a repeating cycle among a limited set of alleles as antibiotics were alternated. Our results showed that susceptibility to antibiotics can be sustainably renewed by cycling structurally similar antibiotics. We anticipate that these results may provide a conceptual framework for managing antibiotic resistance. This approach may also guide sustainable cycling of the drugs used to treat malaria and HIV.

This paper presents a new approach to model general interactions between virtual human agents and objects in virtual worlds. The proposed framework is designed to deal with many of the possible interactions that may arise while simulating a virtual human performing common tasks in a virtual environment. The idea is to include within the object description, all the necessary information to describe how to interact with it. For this, a feature modeling approach is used, by means of a graphical user interface program, to identify object interaction features. Moving parts, functionality instructions and interaction locations are examples of some considered features. Following this approach, the control of the simulation is decentralized from the main animation control, in the sense that some local instructions on how to deal with the object are encapsulated within the object itself. To illustrate the approach, some examples are shown and discussed.

This article investigates the use of 3D immersive virtual environments and 3D prints for interaction with past material culture over traditional observation without manipulation. Our work is motivated by studies in heritage, museum, and cognitive sciences indicating the importance of object manipulation for understanding present and ancient artifacts. While virtual immersive environments and 3D prints have started to be incorporated in heritage research and museum displays as a way to provide improved manipulation experiences, little is known about how these new technologies affect the perception of our past. This article provides first results obtained with three experiments designed to investigate the benefits and tradeoffs in using these technologies. Our results indicate that traditional museum displays limit the experience with past material culture, and reveal how our sample of participants favor tactile and immersive 3D virtual experiences with artifacts over visual non-manipulative experiences with authentic objects.

We present algorithms for the efficient insertion and removal of constraints in Delaunay Triangulations. Constraints are considered to be points or any kind of polygonal lines. Degenerations such as edge overlapping, self-intersections or duplicated points are allowed and are automatically detected and fixed on line. As a result, a fully Dynamic Constrained Delaunay Triangulation is achieved, able to efficiently maintain a consistent triangulated representation of dynamic polygonal domains. Several applications in the fields of data visualization, reconstruction, geographic information systems and collision-free path planning are discussed.

This paper presents a novel whole-body analytical inverse kinematics (IK) method integrating collision avoidance and customizable body control for animating reaching tasks in real-time. Whole-body control is achieved with the interpolation of pre-designed key body postures, which are organized as a function of the direction to the goal to be reached. Arm postures are computed by the analytical IK solution for human-like arms and legs, extended with a new simple search method for achieving postures avoiding joint limits and collisions. In addition, a new IK resolution is presented that directly solves for joints parameterized in the swing-and-twist decomposition. The overall method is simple to implement, fast, and accurate, and therefore suitable for interactive applications controlling the hands of characters. The source code of the IK implementation is provided.

The Local Clearance Triangulation (LCT) of polygonal obstacles is a cell decomposition designed for the efficient computation of locally shortest paths with clearance. This paper presents a revised definition of LCTs, new theoretical results and optimizations, and new algorithms introducing dynamic updates and robustness. Given an input obstacle set with n vertices, a theoretical analysis is proposed showing that LCTs generate a triangular decomposition of O(n) cells, guaranteeing that discrete search algorithms can compute paths in optimal times. In addition, several examples are presented indicating that the number of triangles is low in practice, close to 2n, and a new technique is described for reducing the number of triangles when the maximum query clearance is known in advance. Algorithms for repairing the local clearance property dynamically are also introduced, leading to efficient LCT updates for addressing dynamic changes in the obstacle set. Dynamic updates automatically handle intersecting and overlapping segments with guaranteed robustness, using techniques that combine one exact geometric predicate with adjustment of illegal floating point coordinates. The presented results demonstrate that LCTs are efficient and highly flexible for representing dynamic polygonal environments with clearance information.

We present new techniques that use motion planning algorithms based on probabilistic roadmaps to control 22 degrees of freedom (DOFs) of human‐like characters in interactive applications. Our main purpose is the automatic synthesis of collision‐free reaching motions for both arms, with automatic column control and leg flexion. Generated motions are collision‐free, in equilibrium, and respect articulation range limits. In order to deal with the high (22) dimension of our configuration space, we bias the random distribution of configurations to favor postures most useful for reaching and grasping. In addition, extensions are presented in order to interactively generate object manipulation sequences: a probabilistic inverse kinematics solver for proposing goal postures matching pre‐designed grasps; dynamic update of roadmaps when obstacles change position; online planning of object location transfer; and an automatic stepping control to enlarge the character's reachable space. This is, to our knowledge, the first time probabilistic planning techniques are used to automatically generate collision‐free reaching motions involving the entire body of a human‐like character at interactive frame rates. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three‐Dimensional Graphics and Realism