3714 research outputs found
Sort by
Evolution of adaptive learning for nonlinear dynamic systems: a systematic survey
No full textThe extreme nonlinearity of robotic systems renders the control design step harder. The consideration of adaptive control in robotic manipulation started in the 1970s. However, in the presence of bounded disturbances, the limitations of adaptive control rise considerably, which led researchers to exploit some “algorithm modifications”. Unfortunately, these modifications often require a priori knowledge of bounds on the parameters and the perturbations and noise. In the 1990s, the field of Artificial Neural Networks was hugely investigated in general, and for control of dynamical systems in particular. Several types of Neural Networks (NNs) appear to be promising candidates for control system applications. In robotics, it all boils down to making the actuator perform the desired action. While purely control-based robots use the system model to define their input-output relations, Artificial Intelligence (AI)-based robots may or may not use the system model and rather manipulate the robot based on the experience they have with the system while training or possibly enhance it in real-time as well. In this paper, after discussing the drawbacks of adaptive control with bounded disturbances and the proposed modifications to overcome these limitations, we focus on presenting the work that implemented AI in nonlinear dynamical systems and particularly in robotics. We cite some work that targeted the inverted pendulum control problem using NNs. Finally, we emphasize the previous research concerning RL and Deep RL-based control problems and their implementation in robotics manipulation, while highlighting some of their major drawbacks in the field
The Integrated Probiotic Database: a genomic compendium of bifidobacterial health-promoting strains
No full textBackground: The World Health Organization defines probiotics as “live microorganisms, which when administered in adequate amounts confer a health benefit on the host”. In this framework, probiotic strains should be regarded as safe for human and animal consumption, i.e., they should possess the GRAS (generally recognized as safe) status, notified by the local authorities. Consistently, strains of selected Bifidobacterium species are extensively used as probiotic agents to prevent and ameliorate a broad spectrum of human and/or animal gastrointestinal disorders. Even though probiotic properties are often genus- or species-associated, strain-level differences in the genetic features conferring individual probiotic properties to commercialized bifidobacterial strains have not been investigated in detail. Methods: In this study, we built a genomic database named Integrated Probiotic DataBase (IPDB), whose first iteration consists of common bifidobacterial strains used in probiotic products for which public genome sequences were available, such as members of B. longum subsp. longum, B. longum subsp. infantis, B. bifidum, B. breve, and B. animalis subsp. lactis taxa. Furthermore, the IPDB was exploited to perform comparative genome analyses focused on genetic factors conferring structural, functional, and chemical features predicted to be involved in microbe-host and microbe-microbe interactions.Results and conclusion: Our analyses revealed strain-level genetic differences, underlining the importance of inspecting the strain-specific and outcome-specific efficacy of probiotics. In this context, IPDB represents a valuable resource for obtaining genetic information of well-established bifidobacterial probiotic strains
Cross-feeding interactions between human gut commensals belonging to the Bacteroides and Bifidobacterium genera when grown on dietary glycans
No full textElements of the human gut microbiota metabolise many host- and diet-derived, non-digestible carbohydrates (NDCs). Intestinal fermentation of NDCs salvages energy and resources for the host and generates beneficial metabolites, such as short chain fatty acids, which contribute to host health. The development of functional NDCs that support the growth and/or metabolic activity of specific beneficial gut bacteria, is desirable, but dependent on an in-depth understanding of the pathways of carbohydrate fermentation. The purpose of this review is to provide an appraisal of what is known about the roles of, and interactions between, Bacteroides and Bifidobacterium as key members involved in NDC utilisation. Bacteroides is considered an important primary degrader of complex NDCs, thereby generating oligosaccharides, which in turn can be fermented by secondary degraders. In this review, we will therefore focus on Bacteroides as an NDC-degrading specialist and Bifidobacterium as an important and purported probiotic representative of secondary degraders. We will describe cross-feeding interactions between members of these two genera. We note that there are limited studies exploring the interactions between Bacteroides and Bifidobacterium, specifically concerning β-glucan and arabinoxylan metabolism. This review therefore summarises the roles of these organisms in the breakdown of dietary fibre and the molecular mechanisms and interactions involved. Finally, it also highlights the need for further research into the phenomenon of cross-feeding between these organisms for an improved understanding of these cross-feeding mechanisms to guide the rational development of prebiotics to support host health or to prevent or combat disease associated with microbial dysbiosis
Human exposure assessment of organophosphate esters (OPEs) through dust ingestion and dermal absorption in Colombian cities
No full textConcentrations of 19 organophosphate esters (OPEs) were determined in dust samples collected from house and car indoor microenvironments in three Colombian cities. ∑OPE concentrations ranged from 1.31 to 599 μg/g. Mean concentrations of dust homes were 82.6, 48.3, and 46.7 μg/g for Cartagena, Bogotá, and Medellín, respectively. The pollution inside cars was somewhat higher than in houses, with a mean value of 231 μg/g. Sixteen compounds were detected, being TPHP, DCP, TEP, and TCEP the most frequently detected. As for OPEs with higher levels in houses, we found (mean ± SD) 35.2 ± 37.1 μg/g for TDCIPP in Cartagena, 35.6 ± 80.2 μg/g for TPHP in Cartagena, 15.9 ± 31.4 μg/g for DCP in Cartagena, 35.7 ± 19.1 μg/g for TBOEP in Bogotá, 15.7 ± 14.8 μg/g for 4IPPDPP in Medellín, and 17.5 ± 22.9 μg/g for TCEP in Cartagena, while the highest OPE value found in cars was 176 ± 144 μg/g for TDCIPP. The estimated daily intake (EDI) of OPEs through dust ingestion ranged from 0.001 ng/kg bw/day for adults to 110 ng/kg bw/day for toddlers, while dermal absorption ranged from 0.02 ng/kg bw/day for adults to 42.7 ng/kg bw/day for infants. Overall, the EDIs of dust ingestion were three times greater than those of dust dermal absorption. The estimated EDIs were several orders of magnitude below the corresponding reference doses. However, the incremental lifetime cancer risk (ILCR) for TCEP ranged from 1.1 × 10-5 for infants in Bogotá to 4.3 × 10-4 for adults in Cartagena, while ILCR for TEHP ranged from 8.8 × 10-7 for infants in Bogotá to 1.1 × 10-5 for adults in Bogotá. These estimated ILCRs were higher than the safe limit value of 1 × 10-6 and showed that these populations are exposed to moderate cancer risk
Research subjects suggested to young scientists in mineral processing to tackle future challenges of mining and minerals processing
No full textTension at the hiatus: the role of lengthening procedures and relaxing incisions in paraesophageal hernias
No full textAvoiding tension during hernia repair is the goal of every surgeon. In the setting of laparoscopic paraesophageal hernia (PEH) repair, tension along esophageal length (axial) and between the crura (radial) should be considered. The aim of this narrative review is to summarize the current knowledge on techniques for axial and radial tension assessment and possible minimization during laparoscopic PEH repair
Role of prostate cancer stem-like cells in the development of antiandrogen resistance
No full textAndrogen deprivation therapy (ADT) is the standard of care treatment for advance stage prostate cancer. Treatment with ADT develops resistance in multiple ways leading to the development of castration-resistant prostate cancer (CRPC). Present research establishes that prostate cancer stem-like cells (CSCs) play a central role in the development of treatment resistance followed by disease progression. Prostate CSCs are capable of self-renewal, differentiation, and regenerating tumor heterogeneity. The stemness properties in prostate CSCs arise due to various factors such as androgen receptor mutation and variants, epigenetic and genetic modifications leading to alteration in the tumor microenvironment, changes in ATP-binding cassette (ABC) transporters, and adaptations in molecular signaling pathways. ADT reprograms prostate tumor cellular machinery leading to the expression of various stem cell markers such as Aldehyde Dehydrogenase 1 Family Member A1 (ALDH1A1), Prominin 1 (PROM1/CD133), Indian blood group (CD44), SRY-Box Transcription Factor 2 (Sox2), POU Class 5 Homeobox 1(POU5F1/Oct4), Nanog and ABC transporters. These markers indicate enhanced self-renewal and stemness stimulating CRPC evolution, metastatic colonization, and resistance to antiandrogens. In this review, we discuss the role of ADT in prostate CSCs differentiation and acquisition of CRPC, their isolation, identification and characterization, as well as the factors and pathways contributing to CSCs expansion and therapeutic opportunities
Genetic predisposition to obesity and inflammation in a tri-racial/ethnic breast cancer population
No full textAim: Multiple genes and genetic variants may contribute to racial/ethnic disparities in obesity-associated breast cancer diagnosis and prognosis. Therefore, we evaluate whether racial/ethnic differences in polygenic risk score (PRS) contribute to obesity and inflammatory biomarker in breast cancer patients.Methods: In a tri-racial/ethnic population of 403 breast cancer patients, 21% African American (AA), 65% Hispanic White (HW), and 14% non-Hispanic White (NHW), we evaluated racial/ethnic differences in obesity PRS, the association between PRS and an inflammatory biomarker C-reactive protein (CRP), and its implication in bariatric surgery eligibility. The obesity PRS was constructed via a weighted risk allele model using 35 obesity-related single nucleotide polymorphisms (SNPs). SAS version 9.3 for Windows (SAS Institute, Cary, NC, USA) was used to perform the logistic regression analysis.Results: About 74% of our study population were overweight or obese. The mean ± SD of obesity PRS was 45.03 ± 10.66 for obese patients and 39.36 ± 8.81 for non-obese patients (P < 0.0001). AA patients had a significantly higher obesity PRS than HW and NHW (P < 0.0001). The obesity PRS significantly correlated with body mass index and CRP levels (P < 0.0001) and was associated with bariatric surgery eligibility (OR = 4.32, 95%CI: 1.89-9.87).Conclusion: In summary, multiple obesity-associated SNPs contribute to racial/ethnic disparities in obesity of breast cancer patients; the obesity PRS has application in identifying breast cancer patients with higher genetic risk for obesity who may benefit from more aggressive weight management, such as bariatric surgery to improve breast cancer clinical outcomes
Data sources:
Access Repository Dashboard
Do you manage OAE Publishing (via Crossref)? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!