A Convex Polynomial Force-Motion Model for Planar Sliding: Identification and Application

We propose a polynomial force-motion model for planar sliding. The set of generalized friction loads is the 1-sublevel set of a polynomial whose gradient directions correspond to generalized velocities. Additionally, the polynomial is confined to be convex even-degree homogeneous in order to obey the maximum work inequality, symmetry, shape invariance in scale, and fast invertibility. We present a simple and statistically-efficient model identification procedure using a sum-of-squares convex relaxation. Simulation and robotic experiments validate the accuracy and efficiency of our approach. We also show practical applications of our model including stable pushing of objects and free sliding dynamic simulations.Comment: 2016 IEEE International Conference on Robotics and Automation (ICRA

Author Correction: Attenuation of autophagy impacts on muscle fibre development, starvation induced stress and fibre regeneration following acute injury.

The original version of this Article contained errors. In Figure 5, the distance that “leaky” images were taken from the damaged tissue was not consistent, and there was a partial overlap of the “leaky” and undamaged images for Figure 5D and 5J. In addition, for some panels, the images presented were from different muscle sections. The original Figure 5 and accompanying legend appears below. The original Article has been corrected

When Tutors Self Tutor: What Preservice Teachers Learn about Themselves, Technology, and Teaching during a Time of Remote Learning

Tutoring has been called “the act of saying to somebody else, ‘Let me help you learn’ ” (Chin, Rabow, & Estrada, 2011, p. 2). Teacher preparation programs regularly encourage college students becoming elementary or secondary school teachers to tutor younger learners as an early school-based field experience. Tutors, acting as teachers, must learn how to provide ideas and information to aid and encourage students to accomplish learning goals. Tutors must also assess the effectiveness of their decisions about when and how to implement different instructional strategies to respond to students’ needs

Categorical Models for a Semantically Linear Lambda-calculus

This paper is about a categorical approach to model a very simple Semantically Linear lambda calculus, named Sll-calculus. This is a core calculus underlying the programming language SlPCF. In particular, in this work, we introduce the notion of Sll-Category, which is able to describe a very large class of sound models of Sll-calculus. Sll-Category extends in the natural way Benton, Bierman, Hyland and de Paiva's Linear Category, in order to soundly interpret all the constructs of Sll-calculus. This category is general enough to catch interesting models in Scott Domains and Coherence Spaces

Extrinsic Dexterity: In-Hand Manipulation with External Forces

Abstract — “In-hand manipulation ” is the ability to reposition an object in the hand, for example when adjusting the grasp of a hammer before hammering a nail. The common approach to in-hand manipulation with robotic hands, known as dexterous manipulation [1], is to hold an object within the fingertips of the hand and wiggle the fingers, or walk them along the object’s surface. Dexterous manipulation, however, is just one of the many techniques available to the robot. The robot can also roll the object in the hand by using gravity, or adjust the object’s pose by pressing it against a surface, or if fast enough, it can even toss the object in the air and catch it in a different pose. All these techniques have one thing in common: they rely on resources extrinsic to the hand, either gravity, external contacts or dynamic arm motions. We refer to them as “extrinsic dexterity”. In this paper we study extrinsic dexterity in the context of regrasp operations, for example when switching from a power to a precision grasp, and we demonstrate that even simple grippers are capable of ample in-hand manipulation. We develop twelve regrasp actions, all open-loop and handscripted, and evaluate their effectiveness with over 1200 trials of regrasps and sequences of regrasps, for three different objects (see video [2]). The long-term goal of this work is to develop a general repertoire of these behaviors, and to understand how such a repertoire might eventually constitute a general-purpose in-hand manipulation capability. I

One-Year Analysis of the Prospective Multicenter SENTRY Clinical Trial: Safety and Effectiveness of the Novate Sentry Bioconvertible Inferior Vena Cava Filter

Purpose To prospectively assess the Sentry bioconvertible inferior vena cava (IVC) filter in patients requiring temporary protection against pulmonary embolism (PE). Materials and Methods At 23 sites, 129 patients with documented deep vein thrombosis (DVT) or PE, or at temporary risk of developing DVT or PE, unable to use anticoagulation were enrolled. The primary end point was clinical success, including successful filter deployment, freedom from new symptomatic PE through 60 days before filter bioconversion, and 6-month freedom from filter-related complications. Patients were monitored by means of radiography, computerized tomography (CT), and CT venography to assess filtering configuration through 60 days, filter bioconversion, and incidence of PE and filter-related complications through 12 months. Results Clinical success was achieved in 111 of 114 evaluable patients (97.4%, 95% confidence interval [CI] 92.5%–99.1%). The rate of freedom from new symptomatic PE through 60 days was 100% (n = 129, 95% CI 97.1%–100.0%), and there were no cases of PE through 12 months for either therapeutic or prophylactic indications. Two patients (1.6%) developed symptomatic caval thrombosis during the first month; neither experienced recurrence after successful interventions. There was no filter tilting, migration, embolization, fracture, or caval perforation by the filter, and no filter-related death through 12 months. Filter bioconversion was successful for 95.7% (110/115) at 6 months and for 96.4% (106/110) at 12 months. Conclusions The Sentry IVC filter provided safe and effective protection against PE, with a high rate of intended bioconversion and a low rate of device-related complications, through 12 months of imaging-intense follow-up

Formation and dynamics of van der Waals molecules in buffer-gas traps

We show that weakly bound He-containing van der Waals molecules can be produced and magnetically trapped in buffer-gas cooling experiments, and provide a general model for the formation and dynamics of these molecules. Our analysis shows that, at typical experimental parameters, thermodynamics favors the formation of van der Waals complexes composed of a helium atom bound to most open-shell atoms and molecules, and that complex formation occurs quickly enough to ensure chemical equilibrium. For molecular pairs composed of a He atom and an S-state atom, the molecular spin is stable during formation, dissociation, and collisions, and thus these molecules can be magnetically trapped. Collisional spin relaxations are too slow to affect trap lifetimes. However, helium-3-containing complexes can change spin due to adiabatic crossings between trapped and untrapped Zeeman states, mediated by the anisotropic hyperfine interaction, causing trap loss. We provide a detailed model for Ag3He molecules, using ab initio calculation of Ag-He interaction potentials and spin interactions, quantum scattering theory, and direct Monte Carlo simulations to describe formation and spin relaxation in this system. The calculated rate of spin-change agrees quantitatively with experimental observations, providing indirect evidence for molecular formation in buffer-gas-cooled magnetic traps.Comment: 20 pages, 13 figure

A limited and customized follow-up seems justified after endovascular abdominal aneurysm repair in octogenarians

ObjectiveThe objective of this study was to determine whether long-term follow-up after endovascular aneurysm repair (EVAR) is justified in octogenarians.MethodsBetween September 1996 and October 2011, all patients, including octogenarians, treated for an abdominal aortic aneurysm (AAA) by EVAR were included in a prospective database. Patients older than 80 years and with a nonruptured infrarenal aneurysm treated electively or urgently were included in the study (study group [SG]). Patients with ruptured aneurysms and patients who died during surgery or within the first postoperative month were excluded from further analysis. The control group (CG) consisted of patients younger than 80 years, matched for gender and AAA diameter. All patients were evaluated 4 to 8 weeks after EVAR and then annually thereafter. Follow-up data were complemented by review of the computerized hospital registry and charts and by contact of the patient's general practitioner or referring hospital. Primary outcomes were stent- or aneurysm-related complications and interventions. Secondary outcomes were additional surgical complications and patient survival.ResultsA total number of 193 patients (SG, n = 97; CG, n = 96) were included for analysis. Median age was 80 years, and 88.6% were male. Median follow-up time was 33.6 months (interquartile range [IQR], 12.9-68.3). Stent- and procedure-related postoperative complications were comparable between groups (SG, 41.2%; CG, 39.6%; P = .82). Median time to complication was 2.3 months (IQR, 0.2-19.4) in the SG compared with 18.1 months (IQR, 6.8-50.5) in the CG. The 2-year complication-free survival rates were 58% (SG) and 60% (CG). Interventions were performed significantly less frequently in octogenarians (SG, 8.2%; CG, 19.8%; P < .05). Median time to intervention was 11.1 months (IQR, 2.0-31.0) in the SG compared with 54.3 months (IQR, 15.0-93.2) in the CG. The 2-year intervention-free survival rates were 90% (SG) and 92% (CG). During follow-up, 98 patients died (SG, n = 54; CG, n = 44); median time to death was 31.8 months (IQR, 13.3-66.0) in the SG compared with 44.4 months (IQR, 15.0-77.7) in the CG. One aneurysm-related death occurred in the CG. The 2- and 5-year survival rates were 71% and 32% for the SG compared with 77% and 66% for the CG (P < .05).ConclusionsBecause of the low incidence of secondary procedures and AAA-related deaths in octogenarians, long-term and frequent follow-up after EVAR seems questionable. An adapted and shortened follow-up seems warranted in this patient group

Characterization of a Deswapped Triple Mutant Bovine Odorant Binding Protein

The stability and functionality of GCC-bOBP, a monomeric triple mutant of bovine odorant binding protein, was investigated, in the presence of denaturant and in acidic pH conditions, by both protein and 1-aminoanthracene ligand fluorescence measurements, and compared to that of both bovine and porcine wild type homologues. Complete reversibility of unfolding was observed, though refolding was characterized by hysteresis. Molecular dynamics simulations, performed to detect possible structural changes of the monomeric scaffold related to the presence of the ligand, pointed out the stability of the β-barrel lipocalin scaffold