Interactive teaching of task-oriented robot grasps

This paper focuses on the problem of grasp stability and grasp quality analysis. An elegant way to evaluate the stability of a grasp is to model its wrench space. However, classical grasp quality measures suffer from several disadvantages, the main drawback being that they are not task related. Indeed, constructive approaches for approximating the wrench space including also task information have been rarely considered. This work presents an effective method for task-oriented grasp quality evaluation based on a novel grasp quality measure. We address the general case of multifingered grasps with point contacts with friction.The proposed approach is based on the concept of programming by demonstration and interactive teaching, wherein an expert user provides in a teaching phase a set of exemplar grasps appropriate for the task. Following this phase, a representation of task-related grasps is built. During task planning and execution, a grasp could be either submitted interactively for evaluation by a non-expert user or synthesized by an automatic planning system. Grasp quality is then assessed based on the proposed measure, which takes into account grasp stability along with its suitability for the task. To enable real-time evaluation of grasps, a fast algorithm for computing an approximation of the quality measure is also proposed. Finally, a local grasp optimization technique is described which can amend uncertainties arising in supplied grasps by non-expert users or assist in planning more valuable grasps in the neighborhood of candidate ones.The paper reports experiments performed in virtual reality with both an anthropomorphic virtual hand and a three-fingered robot hand. These experiments suggest the effectiveness and task relevance of the proposed grasp quality measure.     

I2-Imidazoline Ligand CR4056 Improves Memory,Increases ApoE Expression and Reduces BBB Leakage in 5xFAD Mice

Recent evidence suggests that I2-imidazoline ligands have neuroprotective properties in animal models of neurodegeneration, such as Alzheimer’s disease (AD). We recently demonstrated that the I2-ligand BU224 reversed memory impairments in AD transgenic mice and this effect was not because of reductions in amyloid-β (Aβ) deposition. In this study, our aim was to determine the therapeutic potential of the powerful analgesic I2-imidazoline ligand CR4056 in the 5xFAD model of AD, since this ligand has been proven to be safely tolerated in humans. Sub-chronic oral administration of CR4056 (30 mg/kg for 10 days) led to an improvement in recognition memory in 6-month-old 5xFAD mice, but not in wild-type littermates, without affecting Aβ levels or deposition. Our results also revealed a change in the profile of microglia by CR4056, resulting in a suppression of pro-inflammatory activated microglia, but increased the density of astrocytes and the expression of ApoE, which is mainly produced by these glial cells. In addition, CR4056 restored fibrinogen extravasation, affecting the distribution of markers of astrocytic end feet in blood vessels. Therefore, these results suggest that CR4056 protects against Aβ-mediated neuroinflammation and vascular damage, and offers therapeutic potential at any stage of AD.     

Intrinsic Fluorescence of the Active and the Inactive Functional Forms of Human Thymidylate Synthase

The observables associated with protein intrinsic fluorescence – spectra, time decays, anisotropies – offer opportunities to monitor in real time and non-invasively a protein‘s functional form and its interchange with other forms with different functions. We employed these observables to sketch the fluorometric profiles of two functional forms of human thymidylate synthase (hTS), a homodimeric enzyme crucial for cell proliferation and thus targeted by anticancer drugs. The protein takes an active and an inactive form. Stabilization of the latter by peptides that, unlike classical hTS inhibitors, bind it at the monomer/monomer interface offers an alternative inhibition mechanism that promises to avoid the onset of drug resistance in anticancer therapy. The fluorescence features depicted herein can be used as tools to identify and quantify each of the two protein forms in solution, thus making it possible to investigate the kinetic and thermodynamic aspects of the active/inactive conformational interchange. Two examples of fluorometrically monitored interconversion kinetics are provided.     

Analysis of thermoluminescence kinetics of Mg2SiO4:Tb compounds employing an interactive model

The kinetics involved in the thermoluminescence (TL) of Mg₂SiO₄:Tb compounds has been investigated by unfolding glow curves employing both the General Order model and a model that takes into account interactions among traps. The dependence of the glow curve shape on dose is only correctly described if interaction among traps is included in the analysis.     

α-Triazolylboronic Acids: A Promising Scaffold for Effective Inhibitors of KPCs

Boronic acids are known reversible covalent inhibitors of serine β-lactamases. The selectivity and high potency of specific boronates bearing an amide side chain that mimics the β-lactam's amide side chain have been advanced in several studies. Herein, we describe a new class of boronic acids in which the amide group is replaced by a bioisostere triazole. The boronic acids were obtained in a two-step synthesis that relies on the solid and versatile copper-catalyzed azide–alkyne cycloaddition (CuAAC) followed by boronate deprotection. All of the compounds show very good inhibition of the Klebsiella pneumoniae carbapenemase KPC-2, with K_i values ranging from 1 nM to 1 μM, and most of them are able to restore cefepime activity against K. pneumoniae harboring bla_KPC-2. In particular, compound 1 e , bearing a sulfonamide substituted by a thiophene ring, proved to be an excellent KPC-2 inhibitor (K_i=30 nM); it restored cefepime susceptibility in KPC-Kpn cells (MIC=0.5 μg/mL) with values similar to that of vaborbactam (K_i=20 nM, MIC in KPC-Kpn 0.5 μg/mL). Our findings suggest that α-triazolylboronates might represent an effective scaffold for the treatment of KPC-mediated infections.     

Evaluation of virtual fixtures for a robot programming by demonstration interface

We investigate the effectiveness of several types of virtual fixtures in a robot programming by demonstration interface. We show that while all types of virtual fixtures examined yield a significant reduction in the number of errors in tight tolerance peg-in-hole tasks, color and sound fixtures generally outperform a tactile fixture in terms of both execution time of successful trials and error rate. We have found also that when users perceive that the task is very difficult but the system is providing some help by means of a virtual fixture, they tend to spend more time trying to achieve a successful task execution. Thus, for difficult tasks the benefits of virtual fixturing are better reflected in a reduction of the error rate than in a decreased execution time. We conjecture that these trends are related to the limitations of currently available interfaces for human-robot interaction through virtual environments and to the different strategies adopted by the users to cope with such limitations in high-accuracy tasks.     

The amino acid sequences of two acylphosphatase isoforms from fish muscle (Lamna nasus)

Two acylphosphatase isoenzymes have been purified from Lamna nasus muscle, and their complete amino acid sequences have been determined. The former (E1) consists of 99 amino acid residues, while the latter (E2) consists of 102 residues. Both are acetylated at their N termini. E1 has the FFRK active site motif characteristic of all common-type acylphosphatase isoenzymes, whereas E2 contains the CFRM active site motif characteristic of all muscle-type acylphosphatase isoenzymes. They have quite similar kinetic properties. The comparison of sequences of fish E1 and E2 isoenzymes with other known mammalian and bird acylphosphatases reveals that the E2 isoenzyme has an N terminus tail, four residues long, similar to those previously found in all known bird species muscle-type isoenzymes. Among organ-common-type acylphosphatases about 50% of residues are completely conserved, whereas about 60% of muscle-type acylphosphatase residues are completely conserved, indicating that the latter type of isoenzyme has a slower evolutionary rate than the former. The sequences of E1 and E2 acylphosphatases from L. nasus represent the first primary structures of this kind of enzyme determined among fish species.