Robot Active Touch Exploration: Constraints and Strategies

We investigate the problem of using active touch ("haptic") exploration to recognize a 3D object taken from a known set of models. "That is new is that we combine two approaches: (1) using geometric constraints between components to eliminate interpretations, and interpretation tree methods for choosing the best active sensing move; (2) exploratory moves made by tracing continually along the surface of the object (and not through free space). We restrict ourselves to polyhedral, and give a set of geometric constraints tailored for matching components acquired from haptic exploration against components in the models. We present a new constraint using pairs of line segments. We then give a set of active sensing moves, each with an associated cost measure, and our strategies for choosing the next move

Coordinating a Robot Arm and: Multi-finger Hand Using the Quaternion Representation

An autonomous hand-arm system must be able to move its multiple fingertips to specified 3-D world locations. We present an algorithm which, given a desired position and normal for each fingertip, computes all the joint angles for the fingers and arm. Our primary method for handling this under-constrained problem is to optimize a cost function. We also give methods for generating good candidates to be optimized. We present several new techniques for using the quaternion form to optimize rotation. We give experimental results from using the algorithm to apply complicated grasps with a Utah/MIT hand-arm system

Curing the Ake of an Incompetent Expert: A Separate Reviewable Issue

The Supreme Court\u27s mid-1980s decision in Ake v. Oklahoma established the defendant\u27s constitutional right to competent psychiatric assistance. Although many states had already provided indigent defendants access to psychiatric assistance in their defense, it was not until the Court decided Ake that this access was established as his or her constitutional right. However, whether this due process right to expert assistance was satisfied by the mere appointment of a psychiatrist or whether it included the requirement that the expert perform competently had remained unanswered as of 1992. This Comment attempts to address this issue in the affirmative and additionally develops a standard upon which the issue can be reviewed by the courts

Learning the Probability Distribution for Probabilistic Expert Systems

This paper describes a method for learning the joint probability distribution of a set of variables from a sample of instances from the domain. The method is based on a straightforward application of Bayes Law to the problem of estimating individual probabilities from a probability distribution. We use a maximum entropy distribution as an initial estimate and show how this estimate can be easily updated each time an additional example is observed. Although developed for the purpose of estimating the conditional probabilities required for Bayesian inference networks, this method can be adopted to simplify knowledge acquisition in any expert system that uses knowledge in the form of probabilities

Haptic object recognition using a multi-fingered dextrous hand

The use of a dextrous, multifingered hand for high-level object recognition tasks is considered. The paradigm is model-based recognition in which the objects are modeled and recovered as superquadratics, which are shown to have a number of important attributes that make them well suited for such a task. Experiments have been performed to recover the shape of objects using sparse contacts point data from the hand with promising results. The authors also propose an approach to using tactile data in conjunction with the dextrous hand to build a library of grasping and exploration primitives that can be used in recognizing and grasping more complex multipart objects

An Integrated System for Dextrous Manipulation

This paper describes an integrated system for dextrous manipulation using a Utah-MIT hand that allows one to look at the higher levels of control in a number of grasping and manipulation tasks. The system consists of a number of low-level system primitives for grasping, integrated hand and robotic arm movement, tactile sensors mounted on the fingertips, sensing primitives to utilize joint position, tendon force and tactile array feedback, and a high-level programming environment that allows task level scripts to be created for grasping and manipulation tasks. A number of grasping and manipulation tasks are described that have been implemented with this system

A system for programming and controlling a multisensor robotic hand

A system for programming and controlling a multisensor robotic hand (Utah-MIT Hand) is described. Using this system, a number of autonomous tasks that are easily programmed and include combinations of hand-arm actuation with force, position, and tactile sensing have been implemented. The system is controlled at the software level by a programming language DIAL that provides an easy method for expressing the parallel operation of robotic devices. It also provides a convenient way to implement task-level scripts that can then be bound to particular sensors, actuators, and methods for accomplishing a generic grasping or manipulation task. Experiments using the system to pick up and pour from a pitcher, unscrew a lightbulb, and explore planar surfaces are presented

Equivalent Descriptions of Generalized Cylinders

The "equivalence" problem for shape descriptions is that a single three-dimensional shape may have several different descriptions. The Slant Theorem (Shafer) for equivalent generalized cylinder descriptions was proven under the restrictions that the same radius function and the same axis be used for all the descriptions. A proof is given that the theorem still holds when the "same radius function" condition is removed. It does not hold when the "same axis" condition is removed. The ellipsoid is a. counter-example

\u3ci\u3eCandida albicans ISW2 Regulates\u3c/i\u3e Chlamydospore Suspensor Cell Formation and Virulence \u3ci\u3eIn Vivo\u3c/i\u3e in a Mouse Model of Disseminated Candidiasis

Formation of chlamydospores by Candida albicans was an established medical diagnostic test to confirm candidiasis before the molecular era. However, the functional role and pathological relevance of this in vitro morphological transition to pathogenesis in vivo remain unclear. We compared the physical properties of in vitro-induced chlamydospores with those of large C. albicans cells purified by density gradient centrifugation from Candida infected mouse kidneys. The morphological and physical properties of these cells in kidneys of mice infected intravenously with wild type C. albicans confirmed that chlamydospores can form in infected kidneys. A previously reported chlamydospore-null Δisw2/ Δisw2 mutant was used to investigate its role in virulence and chlamydospore induction. Virulence of the Δisw2/Δisw2 mutant strain was reduced 3.4-fold compared to wild type C. albicans or the ISW2 reconstituted strain. Altered host inflammatory reactions to the null mutant further indicate that ISW2 is a virulence factor in C. albicans. ISW2 deletion abolished chlamydospore formation within infected mouse kidneys, whereas the reconstituted strain restored chlamydospore formation in kidneys. Under chlamydospore inducing conditions in vitro, deletion of ISW2 significantly delayed chlamydospore formation, and those late induced chlamydospores lacked associated suspensor cells while attaching laterally to hyphae via novel spore-hypha septa. Our findings establish the induction of chlamydospores by C. albicans during mouse kidney colonization. Our results indicate that ISW2 is not strictly required for chlamydospores formation but is necessary for suspensor cell formation. The importance of ISW2 in chlamydospore morphogenesis and virulence may lead to additional insights into morphological differentiation and pathogenesis of C. albicans in the host microenvironment

\u3ci\u3eCandida albicans ISW2 Regulates\u3c/i\u3e Chlamydospore Suspensor Cell Formation and Virulence \u3ci\u3eIn Vivo\u3c/i\u3e in a Mouse Model of Disseminated Candidiasis

Formation of chlamydospores by Candida albicans was an established medical diagnostic test to confirm candidiasis before the molecular era. However, the functional role and pathological relevance of this in vitro morphological transition to pathogenesis in vivo remain unclear. We compared the physical properties of in vitro-induced chlamydospores with those of large C. albicans cells purified by density gradient centrifugation from Candida infected mouse kidneys. The morphological and physical properties of these cells in kidneys of mice infected intravenously with wild type C. albicans confirmed that chlamydospores can form in infected kidneys. A previously reported chlamydospore-null Δisw2/ Δisw2 mutant was used to investigate its role in virulence and chlamydospore induction. Virulence of the Δisw2/Δisw2 mutant strain was reduced 3.4-fold compared to wild type C. albicans or the ISW2 reconstituted strain. Altered host inflammatory reactions to the null mutant further indicate that ISW2 is a virulence factor in C. albicans. ISW2 deletion abolished chlamydospore formation within infected mouse kidneys, whereas the reconstituted strain restored chlamydospore formation in kidneys. Under chlamydospore inducing conditions in vitro, deletion of ISW2 significantly delayed chlamydospore formation, and those late induced chlamydospores lacked associated suspensor cells while attaching laterally to hyphae via novel spore-hypha septa. Our findings establish the induction of chlamydospores by C. albicans during mouse kidney colonization. Our results indicate that ISW2 is not strictly required for chlamydospores formation but is necessary for suspensor cell formation. The importance of ISW2 in chlamydospore morphogenesis and virulence may lead to additional insights into morphological differentiation and pathogenesis of C. albicans in the host microenvironment