1,899 research outputs found
Adaptive Shape Servoing of Elastic Rods using Parameterized Regression Features and Auto-Tuning Motion Controls
In this paper, we present a new vision-based method to control the shape of
elastic rods with robot manipulators. Our new method computes parameterized
regression features from online sensor measurements that enable to
automatically quantify the object's configuration and establish an explicit
shape servo-loop. To automatically deform the rod into a desired shape, our
adaptive controller iteratively estimates the differential transformation
between the robot's motion and the relative shape changes; This valuable
capability allows to effectively manipulate objects with unknown mechanical
models. An auto-tuning algorithm is introduced to adjust the robot's shaping
motion in real-time based on optimal performance criteria. To validate the
proposed theory, we present a detailed numerical and experimental study with
vision-guided robotic manipulators.Comment: 13 pages, 22 figures, 2 table
RESAM: Requirements Elicitation and Specification for Deep-Learning Anomaly Models with Applications to UAV Flight Controllers
CyberPhysical systems (CPS) must be closely monitored to identify and
potentially mitigate emergent problems that arise during their routine
operations. However, the multivariate time-series data which they typically
produce can be complex to understand and analyze. While formal product
documentation often provides example data plots with diagnostic suggestions,
the sheer diversity of attributes, critical thresholds, and data interactions
can be overwhelming to non-experts who subsequently seek help from discussion
forums to interpret their data logs. Deep learning models, such as Long
Short-term memory (LSTM) networks can be used to automate these tasks and to
provide clear explanations of diverse anomalies detected in real-time
multivariate data-streams. In this paper we present RESAM, a requirements
process that integrates knowledge from domain experts, discussion forums, and
formal product documentation, to discover and specify requirements and design
definitions in the form of time-series attributes that contribute to the
construction of effective deep learning anomaly detectors. We present a
case-study based on a flight control system for small Uncrewed Aerial Systems
and demonstrate that its use guides the construction of effective anomaly
detection models whilst also providing underlying support for explainability.
RESAM is relevant to domains in which open or closed online forums provide
discussion support for log analysis
Entrepreneurs’ Perspective in Coping with the New Normal: Basis for Business Model Development
This descriptive quantitative study was conducted to determine the entrepreneurs’ perspective in coping with the new normal using weighted and average mean as statistical tools in analyzing the data. Findings revealed that the 22 restaurant owners had experienced challenges or business gaps in the new normal situation, which centered on the administrative, production, and financial aspects. Whereas, respondents' perspectives on the opportunity in the new normal situation are on working in flexibility, creating a more responsive business environment, and creating new needs as a break in restaurant business operations. To support the plight of the restaurant entrepreneurs, a business model named 3Ms Strategic Innovation Business Model is developed to reinvent and redesign its corporate strategies in response to the new normal situation. The study concluded that restaurant entrepreneurs in the province of Camarines Norte, Philippines need to adopt a business model suited to the new normal context in order to promote business growth, create competitive advantage, and generate value for their business, its customers, and other stakeholders, making them more empowered individuals in dealing with this crisis
LEAP-UCD-2017 Centrifuge Test Simulation at UNINA
Within the framework of the LEAP-UCD-2017 exercise, Type B simulations of centrifuge tests were conducted assuming a hypoplastic constitutive model for sand. Differently from the most common elastoplastic approach, the hypoplasticity does not decompose the strain rate into elastic and plastic parts and does not use explicitly the notions of the yield surface and plastic potential surface. The process followed to calibrate the constitutive model is presented in detail. The initial state of stresses in the analyzed mesh, the key parameters used in the dynamic simulation phase, and a comparison of the simulation with some experimental results are reported. All the simulations were performed using the model parameters calibrated by using the laboratory test data. Finally, a sensitivity analysis of computed displacement to soil density and ground motion intensity show the influence of such factors on the seismic soil response of liquefiable soils
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Hepatocyte gene expression and DNA methylation as ancestry-dependent mechanisms in African Americans.
African Americans (AAs) are an admixed population with widely varying proportion of West African ancestry (WAA). Here we report the correlation of WAA to gene expression and DNA methylation in AA-derived hepatocytes, a cell type important in disease and drug response. We perform mediation analysis to test whether methylation is a mediator of the effect of ancestry on expression. GTEx samples and a second cohort are used as validation. One hundred and thirty-one genes are associated with WAA (FDR < 0.10), 28 of which replicate and represent 220 GWAS phenotypes. Among PharmGKB pharmacogenes, VDR, PTGIS, ALDH1A1, CYP2C19, and P2RY1 nominally associate with WAA (p < 0.05). We find 1037 WAA-associated, differentially methylated regions (FDR < 0.05), with hypomethylated genes enriched in drug-response pathways. In conclusion, WAA contributes to variability in hepatocyte expression and DNA methylation with identified genes previously implicated for diseases disproportionately affecting AAs, including cardiovascular (PTGIS, PLAT) and renal (APOL1) disease, and drug response (CYP2C19)
Defining language impairments in a subgroup of children with autism spectrum disorder
Autism spectrum disorder (ASD) is diagnosed on the basis of core impairments in pragmatic language skills, which are found across all ages and subtypes. In contrast, there is significant heterogeneity in language phenotypes, ranging from nonverbal to superior linguistic abilities, as defined on standardized tests of vocabulary and grammatical knowledge. The majority of children are verbal but impaired in language, relative to age-matched peers. One hypothesis is that this subgroup has ASD and co-morbid specific language impairment (SLI). An experiment was conducted comparing children with ASD to children with SLI and typically developing controls on aspects of language processing that have been shown to be impaired in children with SLI: repetition of nonsense words. Patterns of performance among the children with ASD and language impairment were similar to those with SLI, and contrasted with the children with ASD and no language impairment and typical controls, providing further evidence for the hypothesis that a subgroup of children with ASD has co-morbid SLI. The findings are discussed in the context of brain imaging studies that have explored the neural bases of language impairment in ASD and SLI, and overlap in the genes associated with elevated risk for these disorders.M01 RR00533 - NCRR NIH HHS; R01 DC10290 - NIDCD NIH HHS; U19 DC03610 - NIDCD NIH HH
Revisiting Scalar and Pseudoscalar Couplings with Nucleons
Certain dark matter interactions with nuclei are mediated possibly by a
scalar or pseudoscalar Higgs boson. The estimation of the corresponding cross
sections requires a correct evaluation of the couplings between the scalar or
pseudoscalar Higgs boson and the nucleons. Progress has been made in two
aspects relevant to this study in the past few years. First, recent lattice
calculations show that the strange-quark sigma term and the
strange-quark content in the nucleon are much smaller than what are expected
previously. Second, lattice and model analyses imply sizable SU(3) breaking
effects in the determination on the axial-vector coupling constant that
in turn affect the extraction of the isosinglet coupling and the
strange quark spin component from polarized deep inelastic
scattering experiments. Based on these new developments, we re-evaluate the
relevant nucleon matrix elements and compute the scalar and pseudoscalar
couplings of the proton and neutron. We also find that the strange quark
contribution in both types of couplings is smaller than previously thought.Comment: 17 pages, Sec. II is revised and the pion-nucleon sigma term
extracted from the scattering data is discussed. Version to appear in JHE
Histone Acetylation-Mediated Regulation of the Hippo Pathway
The Hippo pathway is a signaling cascade recently found to play a key role in tumorigenesis therefore understanding the mechanisms that regulate it should open new opportunities for cancer treatment. Available data indicate that this pathway is controlled by signals from cell-cell junctions however the potential role of nuclear regulation has not yet been described. Here we set out to verify this possibility and define putative mechanism(s) by which it might occur. By using a luciferase reporter of the Hippo pathway, we measured the effects of different nuclear targeting drugs and found that chromatin-modifying agents, and to a lesser extent certain DNA damaging drugs, strongly induced activity of the reporter. This effect was not mediated by upstream core components (i.e. Mst, Lats) of the Hippo pathway, but through enhanced levels of the Hippo transducer TAZ. Investigation of the underlying mechanism led to the finding that cancer cell exposure to histone deacetylase inhibitors induced secretion of growth factors and cytokines, which in turn activate Akt and inhibit the GSK3 beta associated protein degradation complex in drug-affected as well as in their neighboring cells. Consequently, expression of EMT genes, cell migration and resistance to therapy were induced. These processes were suppressed by using pyrvinium, a recently described small molecule activator of the GSK 3 beta associated degradation complex. Overall, these findings shed light on a previously unrecognized phenomenon by which certain anti-cancer agents may paradoxically promote tumor progression by facilitating stabilization of the Hippo transducer TAZ and inducing cancer cell migration and resistance to therapy. Pharmacological targeting of the GSK3 beta associated degradation complex may thus represent a unique approach to treat cancer. © 2013 Basu et al
Phenotypic redshifts with self-organizing maps: A novel method to characterize redshift distributions of source galaxies for weak lensing
Wide-field imaging surveys such as the Dark Energy Survey (DES) rely on
coarse measurements of spectral energy distributions in a few filters to
estimate the redshift distribution of source galaxies. In this regime, sample
variance, shot noise, and selection effects limit the attainable accuracy of
redshift calibration and thus of cosmological constraints. We present a new
method to combine wide-field, few-filter measurements with catalogs from deep
fields with additional filters and sufficiently low photometric noise to break
degeneracies in photometric redshifts. The multi-band deep field is used as an
intermediary between wide-field observations and accurate redshifts, greatly
reducing sample variance, shot noise, and selection effects. Our implementation
of the method uses self-organizing maps to group galaxies into phenotypes based
on their observed fluxes, and is tested using a mock DES catalog created from
N-body simulations. It yields a typical uncertainty on the mean redshift in
each of five tomographic bins for an idealized simulation of the DES Year 3
weak-lensing tomographic analysis of , which is a
60% improvement compared to the Year 1 analysis. Although the implementation of
the method is tailored to DES, its formalism can be applied to other large
photometric surveys with a similar observing strategy.Comment: 24 pages, 11 figures; matches version accepted to MNRA
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