49 research outputs found
Adaptive Stochastic Optimisation of Nonconvex Composite Objectives
In this paper, we propose and analyse a family of generalised stochastic
composite mirror descent algorithms. With adaptive step sizes, the proposed
algorithms converge without requiring prior knowledge of the problem. Combined
with an entropy-like update-generating function, these algorithms perform
gradient descent in the space equipped with the maximum norm, which allows us
to exploit the low-dimensional structure of the decision sets for
high-dimensional problems. Together with a sampling method based on the
Rademacher distribution and variance reduction techniques, the proposed
algorithms guarantee a logarithmic complexity dependence on dimensionality for
zeroth-order optimisation problems.Comment: arXiv admin note: substantial text overlap with arXiv:2208.0457
FABRIC: A Framework for the Design and Evaluation of Collaborative Robots with Extended Human Adaptation
A limitation for collaborative robots (cobots) is their lack of ability to
adapt to human partners, who typically exhibit an immense diversity of
behaviors. We present an autonomous framework as a cobot's real-time
decision-making mechanism to anticipate a variety of human characteristics and
behaviors, including human errors, toward a personalized collaboration. Our
framework handles such behaviors in two levels: 1) short-term human behaviors
are adapted through our novel Anticipatory Partially Observable Markov Decision
Process (A-POMDP) models, covering a human's changing intent (motivation),
availability, and capability; 2) long-term changing human characteristics are
adapted by our novel Adaptive Bayesian Policy Selection (ABPS) mechanism that
selects a short-term decision model, e.g., an A-POMDP, according to an estimate
of a human's workplace characteristics, such as her expertise and collaboration
preferences. To design and evaluate our framework over a diversity of human
behaviors, we propose a pipeline where we first train and rigorously test the
framework in simulation over novel human models. Then, we deploy and evaluate
it on our novel physical experiment setup that induces cognitive load on humans
to observe their dynamic behaviors, including their mistakes, and their
changing characteristics such as their expertise. We conduct user studies and
show that our framework effectively collaborates non-stop for hours and adapts
to various changing human behaviors and characteristics in real-time. That
increases the efficiency and naturalness of the collaboration with a higher
perceived collaboration, positive teammate traits, and human trust. We believe
that such an extended human adaptation is key to the long-term use of cobots.Comment: The article is in review for publication in International Journal of
Robotics Researc
Gastric Necrosis due to Acute Massive Gastric Dilatation
Gastric necrosis due to acute massive gastric dilatation is relatively rare. Vascular reasons, herniation, volvulus, acute gastric dilatation, anorexia, and bulimia nervosa play a role in the etiology of the disease. Early diagnosis and treatment are highly important as the associated morbidity and mortality rates are high. In this case report, we present a case of gastric necrosis due to acute gastric dilatation accompanied with the relevant literature
Very Short-Term Power System Frequency Forecasting
Power system frequency plays a pivotal role in ensuring the security, adequacy, and integrity of a power system. While some frequency response services are automatically delivered to maintain the frequency within the stipulated limits, certain cases may require that system operators (SOs) manually intervene-against the clock-to take the necessary preventive or corrective actions. As such, SOs can be greatly aided by practical tools that afford them greater temporal leeway. To this end, we propose a methodology to forecast the power system frequency in the subsequent minute. We perform an extensive analysis so as to identify the factors that influence power system frequency. By effectively exploiting the identified factors, we develop a forecasting methodology that harnesses the long short-term memory model. We demonstrate the effectiveness of the proposed methodology on Great Britain transmission system frequency data using comparative assessments with selected benchmarks based on various evaluation metrics.Publisher's Versio
A Therapeutic and Diagnostic Dilemma: Granular Cell Tumor of the Breast
Six to eight percent of granular cell tumors are seen in the breast. Although mostly benign, they rarely have malignant features clinically and radiologically reminding of breast cancer. This may lead to a potential misdiagnosis of breast carcinoma and overtreatment of patients. The final diagnosis is made by immunohistochemical examination. We performed excisional biopsy on a patient who was diagnosed to have a breast mass. The histopathological examination of the mass revealed granular cell tumor
E2F-1 binding affinity for pRb is not the only determinant of the E2F-1 activity
<p>E2F-1 is the major cellular target of pRB and is regulated by pRB during cell proliferation. Interaction between pRB and E2F-1 is dependent on the phosphorylation status of pRB. Despite the fact that E2F-1 and pRB have antagonistic activities when they are overexpressed, the role of the E2F-1-pRB interaction in cell growth largely remains unknown. Ideally, it would be better to study the properties of a pRB mutant that fails to bind to E2F, but retains all other activities. To date, no pRB mutation has been characterized in sufficient detail to show that it specifically eliminates E2F binding but leaves other interactions intact. An alternative approach to this issue is to ask whether mutations that change E2F proteins binding affinity to pRB are sufficient to change cell growth in aspect of cell cycle and tumor formation. Therefore, we used the E2F-1 mutants including E2F-1/S332-7A, E2F-1/S375A, E2F-1/S403A, E2F-1/Y411A and E2F-1/L132Q that have different binding affinities for pRB to better understand the roles of the E2F-1 phosphorylation and E2F-1-pRB interaction in the cell cycle, as well as in transformation and gene expression. Data presented in this study suggests that <i>in vivo</i> phosphorylation at amino acids 332-337, 375 and 403 is important for the E2F-1 and pRB interaction <i>in vivo</i>. However, although E2F-1 mutants 332-7, 375 and 403 showed similar binding affinity to pRB, they showed different characteristics in transformation efficiency, G<sub>0</sub> accumulation, and target gene experiments.</p