977 research outputs found
Learning motor skills from partially observed movements executed at different speeds
Learning motor skills from multiple demonstrations
presents a number of challenges. One of those challenges
is the occurrence of occlusions and lack of sensor coverage,
which may corrupt part of the recorded data. Another issue
is the variability in speed of execution of the demonstrations,
which may require a way of finding the correspondence between
the time steps of the different demonstrations. In this paper,
an approach to learn motor skills is proposed that accounts
both for spatial and temporal variability of movements. This
approach, based on an Expectation-Maximization algorithm to
learn Probabilistic Movement Primitives, also allows for learning
motor skills from partially observed demonstrations, which may
result from occlusion or lack of sensor coverage. An application
of the algorithm proposed in this work lies in the field of
Human-Robot Interaction when the robot has to react to human
movements executed at different speeds. Experiments in which
a robotic arm receives a cup handed over by a human illustrate
this application. The capabilities of the algorithm in learning
and predicting movements are also evaluated in experiments
using a data set of letters and a data set of golf putting
movements
Movement primitives with multiple phase parameters
Movement primitives are concise movement representations that can be learned from human demonstrations, support generalization to novel situations and modulate the speed of execution of movements. The speed modulation mechanisms proposed so far are limited though, allowing only for uniform speed modulation or coupling changes in speed to local measurements of forces, torques or other quantities. Those approaches are not enough when dealing with general velocity constraints. We present a movement primitive formulation that can be used to non-uniformly adapt the speed of execution of a movement in order to satisfy a given constraint, while maintaining similarity in shape to the original trajectory. We present results using a 4-DoF robot arm in a minigolf setup
Heparin Increases HLA-G Levels in Primary Antiphospholipid Syndrome
Objectives. The aim of this study was to investigate the HLA-G serum levels in Primary Antiphospholipid Syndrome (PAPS) patients, its impact on clinical and laboratory findings, and heparin treatment. Methods. Forty-four PAPS patients were age and gender matched with 43 controls. HLA-G serum levels were measured using an enzyme-linked immunosorbent assay (ELISA). Results. An increase in soluble HLA-G levels was found in patients compared to controls (3.35 (0–22.9) versus 1.1 (0–14), P = 0.017). There were no significant differences in HLA-G levels between patients with and without obstetric events, arterial thrombosis, venous thrombosis, or stroke. Sixty-six percent of patients were being treated with heparin. Interestingly, patients treated with heparin had higher HLA-G levels than ones who were not treated with this medication (5 (0–22.9) versus 1.8 (0–16) ng/mL, P = 0.038). Furthermore, patients on heparin who experienced obstetric events had a trend to increased HLA-G levels compared to patients who were not on heparin and did not have obstetric events (5.8 (0–22.9) versus 2 (0–15.2) ng/mL, P = 0.05). Conclusion. This is the first study to demonstrate that serum HLA-G levels are increased in APS patients. We also demonstrated that heparin increases HLA-G levels and may increase tolerance towards autoantigens
Heparin Increases HLA-G Levels in Primary Antiphospholipid Syndrome
Objectives. The aim of this study was to investigate the HLA-G serum levels in Primary Antiphospholipid Syndrome (PAPS) patients, its impact on clinical and laboratory findings, and heparin treatment. Methods. Forty-four PAPS patients were age and gender matched with 43 controls. HLA-G serum levels were measured using an enzyme-linked immunosorbent assay (ELISA). Results. An increase in soluble HLA-G levels was found in patients compared to controls (3.35 (0–22.9) versus 1.1 (0–14), P = 0.017). There were no significant differences in HLA-G levels between patients with and without obstetric events, arterial thrombosis, venous thrombosis, or stroke. Sixty-six percent of patients were being treated with heparin. Interestingly, patients treated with heparin had higher HLA-G levels than ones who were not treated with this medication (5 (0–22.9) versus 1.8 (0–16) ng/mL, P = 0.038). Furthermore, patients on heparin who experienced obstetric events had a trend to increased HLA-G levels compared to patients who were not on heparin and did not have obstetric events (5.8 (0–22.9) versus 2 (0–15.2) ng/mL, P = 0.05). Conclusion. This is the first study to demonstrate that serum HLA-G levels are increased in APS patients. We also demonstrated that heparin increases HLA-G levels and may increase tolerance towards autoantigens
Comparison of disc diffusion, Etest and broth microdilution for testing susceptibility of carbapenem-resistant P. aeruginosa to polymyxins
Abstract\ud
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Background\ud
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Considering the increasing use of polymyxins to treat infections due to multidrug resistant Gram-negative in many countries, it is important to evaluate different susceptibility testing methods to this class of antibiotic.\ud
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Methods\ud
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Susceptibility of 109 carbapenem-resistant P. aeruginosa to polymyxins was tested comparing broth microdilution (reference method), disc diffusion, and Etest using the new interpretative breakpoints of Clinical and Laboratory Standards Institute.\ud
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Results\ud
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Twenty-nine percent of isolates belonged to endemic clone and thus, these strains were excluded of analysis. Among 78 strains evaluated, only one isolate was resistant to polymyxin B by the reference method (MIC: 8.0 μg/mL). Very major and major error rates of 1.2% and 11.5% were detected comparing polymyxin B disc diffusion with the broth microdilution (reference method). Agreement within 1 twofold dilution between Etest and the broth microdilution were 33% for polymyxin B and 79.5% for colistin. One major error and 48.7% minor errors were found comparing polymyxin B Etest with broth microdilution and only 6.4% minor errors with colistin. The concordance between Etest and the broth microdilution (reference method) was respectively 100% for colistin and 90% for polymyxin B.\ud
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Conclusion\ud
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Resistance to polymyxins seems to be rare among hospital carbapenem-resistant P. aeruginosa isolates over a six-year period. Our results showed, using the new CLSI criteria, that the disc diffusion susceptibility does not report major errors (false-resistant results) for colistin. On the other hand, showed a high frequency of minor errors and 1 very major error for polymyxin B. Etest presented better results for colistin than polymyxin B. Until these results are reproduced with a large number of polymyxins-resistant P. aeruginosa isolates, susceptibility to polymyxins should be confirmed by a reference method.Financial support: Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP).Financial support: Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Learning interaction for collaborative tasks with probabilistic movement primitives
This paper proposes a probabilistic framework
based on movement primitives for robots that work in collaboration
with a human coworker. Since the human coworker
can execute a variety of unforeseen tasks a requirement of our
system is that the robot assistant must be able to adapt and
learn new skills on-demand, without the need of an expert
programmer. Thus, this paper leverages on the framework
of imitation learning and its application to human-robot interaction
using the concept of Interaction Primitives (IPs).
We introduce the use of Probabilistic Movement Primitives
(ProMPs) to devise an interaction method that both recognizes
the action of a human and generates the appropriate movement
primitive of the robot assistant. We evaluate our method
on experiments using a lightweight arm interacting with a
human partner and also using motion capture trajectories of
two humans assembling a box. The advantages of ProMPs in
relation to the original formulation for interaction are exposed
and compared
CAR T-cell Infusion Following Checkpoint Inhibition Can Induce Remission in Chemorefractory Post-transplant Lymphoproliferative Disorder of the CNS
Lyra: Password-Based Key Derivation with Tunable Memory and Processing Costs
We present Lyra, a password-based key derivation scheme based on cryptographic sponges. Lyra was designed to be strictly sequential (i.e., not easily parallelizable), providing strong security even against attackers that use multiple processing cores (e.g., custom hardware or a powerful GPU). At the same time, it is very simple to implement in software and allows legitimate users to fine-tune its memory and processing costs according to the desired level of security against brute force password guessing. We compare Lyra with similar-purpose state-of-the-art solutions, showing how our proposal provides a higher security level and overcomes limitations of existing schemes. Specfically, we show that if we fix Lyra\u27s total processing time t in a legitimate platform, the cost of a memory-free attack against the algorithm is exponential, while the best known result in the literature (namely, against the scrypt algorithm) is quadratic. In addition, for an identical same processing time, Lyra allows for a higher memory usage than its counterparts, further increasing the cost of brute force attacks
Abordagem do Conteúdo de Mistura envolvendo o Tratamento de Água: análise de uma proposta didática para o ensino de Química
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