bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leveraging Conventional Control to Improve Performance of Systems Using Reinforcement Learning
Authors: Eaglin Gerald , Vaughan Joshua 
Published: January 2021

Abstract
While many model-based methods have been proposed for optimal control, it is often difficult to generate model-based optimal controllers for nonlinear systems. One model-free method to solve for optimal control policies is reinforcement learning. Reinforcement learning iteratively trains an agent to optimize a reward function. However, agents often perform poorly at the beginning of training and require a large number of trials to converge to a successful policy. A method is proposed to incorporate domain knowledge of dynamics and control into the controllers using reinforcement learning to reduce the training time needed. Simulations are presented to compare the performance of agents utilizing domain knowledge to those that do not use domain knowledge. The results show that the agents with domain knowledge can accomplish the desired task with less training time than those without domain knowledge.
Developmental Reinforcement Learning of Control Policy of a Quadcopter UAV With Thrust Vectoring Rotors
Authors: Deshpande Aditya M. , Kumar Rumit , Minai Ali A. , Kumar Manish 
Published: January 2021

Abstract
In this paper, we present a novel developmental reinforcement learning-based controller for a quadcopter with thrust vectoring capabilities. This multirotor UAV design has tilt-enabled rotors. It utilizes the rotor force magnitude and direction to achieve the desired state during flight. The control policy of this robot is learned using the policy transfer from the learned controller of the quadcopter (comparatively simple UAV design without thrust vectoring). This approach allows learning a control policy for systems with multiple inputs and multiple outputs. The performance of the learned policy is evaluated by physics-based simulations for the tasks of hovering and way-point navigation. The flight simulations utilize a flight controller based on reinforcement learning without any additional PID components. The results show faster learning with the presented approach as opposed to learning the control policy from scratch for this new UAV design created by modifications in a conventional quadcopter, i.e., the addition of more degrees of freedom (4-actuators in conventional quadcopter to 8-actuators in tilt-rotor quadcopter). We demonstrate the robustness of our learned policy by showing the recovery of the tilt-rotor platform in the simulation from various non-static initial conditions in order to reach a desired state. The developmental policy for the tilt-rotor UAV also showed superior fault tolerance when compared with the policy learned from the scratch. The results show the ability of the presented approach to bootstrap the learned behavior from a simpler system (lower-dimensional action-space) to a more complex robot (comparatively higher-dimensional action-space) and reach better performance faster.
Dynamic Modeling of Voice Coil Motor-Actuated Flexible Membranes
Authors: Shi Hongyang , Pinto Thassyo , Qi Xinda , Coleman Demetris , Matt Silvia , Hou Weilin , Tan Xiaobo 
Published: January 2021

Abstract
In this paper, we derive a dynamical model for a controllable flexible membrane which is point-actuated by distributed voice coil motors (VCM) connected to it. Besides the modal analysis of the membrane motion, which is the only dynamics discussed in most of related published works treating external pressures as inputs, we integrate the dynamics of the voice coil motors including mechanics and electrical dynamics into the whole system, leaving the electrical signals as inputs to the VCM-actuated membrane system, which is useful for practical application. Also, the multiple-input-multiple-output (MIMO) system is simplified by transforming the dynamics equations into Laplace domain and into a matrix form, which makes the derived transfer functions concise and easier for analysis. It is demonstrated that the eigenmodes of an undamped free-vibration model can be used for approximating the deflection of a forced damping membrane. Furthermore, a reduced-order model is constructed for the flexible membrane system with two voice coil motors symmetrically located on the diameter of the membrane, which is subsequently validated with experimental results obtained on a 2-by-1-VCM-actuated membrane prototype.
Nonholonomic Systems With Redundant Degrees of Freedom Can Exploit Nonlinear Frequency Response to Improve Speed and Efficiency of Locomotion
Authors: Fedonyuk Vitaliy , Rodwell Colin , Tallapragada Phanindra 
Published: January 2021

Abstract
Rigid body nonholonomic systems serve as models for locomotion of several terrestrial animals such as snakes as well as for fish-like swimming motion. Several well known nonholonomic systems have also found applications in the field of mobile robotics in everything from wheeled vehicles to articulated snake like robots. However, one aspect of their dynamics has remained unexplored. This is to do with the effects of increasing the degrees of freedom by adding additional ‘segments’ such as in a chain, with the joints between segments having a nonzero torsional stiffness. Such nonholonomic systems when subjected to periodic actuation or inputs have additional modes of oscillation. The interplay of the nonholonomic constraints, linear elastic potentials and additional degrees of freedom can produce rich frequency-amplitude response in the dynamics of the system and can lead to significantly higher speed and efficiency. In this paper we explore such dynamics with the example of a well known nonholonomic system, the Chaplygin sleigh and a variant of it with an additional degree of freedom. Such models can be expected to better match the dynamics of biological swimmers and have widespread applications for soft and under-actuated robots.
Protracted northward drifting of South China during the assembly of Gondwana: Constraints from the spatial-temporal provenance comparison of Neoproterozoic–Cambrian strata
Authors: Chen Qiong , Zhao Guochun , Sun Min 
Published: January 2021

Abstract
Neoproterozoic to Paleozoic sedimentation shows systematic temporal-spatial variations within South China, which must be considered in reconstructing geological evolution of South China in response to global plate reorganization from the breakup of Rodinia to the assembly of Gondwana. We use &gt;1000 new U-Pb and Hf isotopic data for detrital zircons from Neoproterozoic–Cambrian strata across the western (i.e., Longmenshan) and eastern (i.e., Wuyishan) margins of South China, coupled with compiled stratigraphic and magmatic information, to constrain change in provenance through time. First-order conclusions are as follows: (1) detrital zircons from the Neoproterozoic strata of the two margins were mainly sourced from the Panxi-Hannan arc and the Jiangnan orogen, signaling a rough self-sufficient sedimentary system; (2) newly identified Cambrian molasse-like sediments in the western margin, in which abundant detrital zircons are 550–500 Ma old with positive εHf(t) values, were mainly derived from the 580–500 Ma Cadomian arc belt along the Iran-Turkey margin; and (3) the Cambrian sediments in the eastern margin document more increased contributions from the Grenvillian-age provinces most possibly in Australia. Such spatial-temporal provenance variations signal the northward drifting of South China, from a position connecting with Iran-Turkey and northern India to that approaching Australia during the late Neoproterozoic–Cambrian period. We highlight that the activity of oblique oceanic-continental convergence accreted Asian terranes onto the northern margin of Gondwana, hence contributing to the ultimate Gondwana architecture under global plate reorganization.
Variability in preventive care practices among US adults with diabetes mellitus
Authors: Baccaglini Lorena , Kusi Appiah Adams , Ray Mahua , Yu Fang 
Published: January 2021

IntroductionPatients with diabetes are advised to follow standard medical care including daily blood glucose and foot checks, eye examinations with pupil dilation, and cholesterol checks to prevent diabetes-related complications. It is unclear how these practices currently vary across different US population subgroups. The objective of this study was to assess variation in overall and individual diabetes care practices and identify specific factors associated with differences in these practices in a representative sample of US diabetic adults.Research design and methodsCross-sectional data were from the 2017 Behavioral Risk Factor Surveillance System. Survey logistic regression was used to account for the complex sampling design.ResultsAmong 30 780 eligible participants, 8957 (equivalent to 28% of the target population) followed all four diabetes care practices. Insulin-dependent participants had higher adjusted odds (adjusted OR=2.95; 95% CI 2.62 to 3.31) of following all four diabetic care practices compared with those who did not. Cost-related variables (having healthcare coverage and/or a personal doctor) were positively associated with diabetes care practices, with the strongest association observed for adherence to more costly practices (annual eye examination and cholesterol check) versus less costly ones (daily blood glucose check, daily foot check).ConclusionsOur findings suggest the need for diabetes care practice-specific and population subgroup-specific public health interventions to encourage early adherence to diabetic care practices and reduce complications.
Impact on health and provision of healthcare services during the COVID-19 lockdown in India: a multicentre cross-sectional study
Authors: Raman Rajiv , Rajalakshmi Ramachandran , Surya Janani , Ramakrishnan Radha , Sivaprasad Sobha , Conroy Dolores , Thethi Jitendra Pal , Mohan V , Netuveli Gopalakrishnan 
Published: January 2021

IntroductionThe COVID-19 pandemic resulted in a national lockdown in India from midnight on 25 March 2020, with conditional relaxation by phases and zones from 20 April. We evaluated the impact of the lockdown in terms of healthcare provisions, physical health, mental health and social well-being within a multicentre cross-sectional study in India.MethodsThe SMART India study is an ongoing house-to-house survey conducted across 20 regions including 11 states and 1 union territory in India to study diabetes and its complications in the community. During the lockdown, we developed an online questionnaire and delivered it in English and seven popular Indian languages (Hindi, Tamil, Marathi, Telegu, Kannada, Bengali, Malayalam) to random samples of SMART-India participants in two rounds from 5 May 2020 to 24 May 2020. We used multivariable logistic regression to evaluate the overall impact on health and healthcare provision in phases 3 and 4 of lockdown in red and non-red zones and their interactions.ResultsA total of 2003 participants completed this multicentre survey. The bivariate relationships between the outcomes and lockdown showed significant negative associations. In the multivariable analyses, the interactions between the red zones and lockdown showed that all five dimensions of healthcare provision were negatively affected (non-affordability: OR 1.917 (95% CI 1.126 to 3.264), non-accessibility: OR 2.458 (95% CI 1.549 to 3.902), inadequacy: OR 3.015 (95% CI 1.616 to 5.625), inappropriateness: OR 2.225 (95% CI 1.200 to 4.126) and discontinuity of care: OR 6.756 (95% CI 3.79 to 12.042)) and associated depression and social loneliness.ConclusionThe impact of COVID-19 pandemic and lockdown on health and healthcare was negative. The exaggeration of income inequality during lockdown can be expected to extend the negative impacts beyond the lockdown.
Acute pain management among patients with opioid maintenance therapy: specificities and difficulties identified in primary care: a qualitative study
Authors: Guillou Landreat Morgane , Baillot Melia , Le Goff Delphine , Le Reste Jean Yves 
Published: January 2021

ObjectivesIn the last 30 years, opioid maintenance treatment prescription (OMT) has changed patients’ and also changed physicians’ practices. General practitioners (GPs) have to deal with patients on OMT who are in acute pain. The objective of this qualitative study was to explore medical care challenges and solutions identified by GPs in the management of acute pain among patients receiving OMT.Design and settingQualitative study with semistructured interviews were used as a data collection technique with a sampling strategy using a snowball sampling method to obtain a purposive sample of practicing GPs. Analysis was undertaken using a thematic analysis method.ParticipantsTwelve GPs, working in France (Brittany) who prescribe OMT were interviewed.ResultsThe thematic analysis resulted in two main themes relating to specificities and difficulties identified: (1) Medical care and training challenges identified by GPs treating patients on OMT with acute pain, with four subthemes : management of these situations not concerning primary care, lack of training prompts GPs to rely on peer and specialist support, lack of guidelines and conflicting recommendations between clinicians in different settings (2) linked to the patient–GP relationship, with six subthemes: Implementing an individualised centred approach, acute pain management during OMT relies on a relationship based on trust, GPs found difficulties in evaluating and treating pain, difficulties in care adherence, fear of patients destabilisation, fear of misuse and diversion.ConclusionThe complexity of acute pain and OMT entails significant challenges for clinicians and patients. In primary care, it is hard to achieve a balance between pain relief and opioid use disorder treatment, in a global patient-centred approach. Fear of misuse or diversion was not a important factor, except for patients not known to the practitioners, but GPs were concerned with the risks of patient destabilisation in situations of acute pain.
Quality of life in paediatric solid tumours: a randomised study of metronomic chemotherapy versus placebo
Authors: Pramanik Raja , Agarwala Sandeep , Sreenivas Vishnubhatla , Dhawan Deepa , Bakhshi Sameer 
Published: January 2021

ObjectiveHealth-related quality of life (HRQoL) is an important outcome for paediatric cancer studies. We compared the HRQoL between patients of progressive paediatric solid tumours randomised to metronomic chemotherapy versus placebo.MethodsIn this double-blinded, placebo-controlled randomised study of 108 children with progressive malignancies, HRQoL was evaluated using the PedsQOL Cancer module V.3 at baseline (A1), A2 (9 weeks or earlier if progressed) or A3 (18 weeks or earlier if progressed).ResultsThere was no statistically significant difference in the change in quality of life produced by each arm from A1 to A2 in either mean total scores or individual domain scores, reported by children or their parents. On analysing the response according to the minimal clinically important difference, defined as an improvement by 4.5 points, we found no significant differences, be it among bone-sarcomas, other tumours, responders (those who received ≥9 weeks of treatment) or non-responders.ConclusionsThe present study concludes that there was no significant difference in HRQoL, between the patients in the two arms at second and later assessments. This is consistent with the other survival endpoints in the study.Trial registration numberClinical trial registration: clinicaltrials.gov Identifier:NCT01858571.
Antibiotic use towards the end of life: development of good practice recommendations
Authors: Seaton R Andrew , Cooper Lesley , Fairweather Jack , Fenning Stephen , Ferguson Libby , Galbraith Susan , Duffy Tony , Sneddon Jacqueline 
Published: January 2021

ObjectivesDevelopment of evidence-based good practice recommendations for clinicians considering the use of antibiotics in patients towards the end of life.DesignA multiprofessional group of experts in end-of-life care and antimicrobial stewardship was convened. Findings from a scoping review of the literature and a consultation of clinicians were triangulated. Expert discussion was used to generate consensus on how to approach decision-making.SettingRepresentatives from hospital and a range of community health and care settings.ParticipantsMedical, pharmacy and nursing professionals.Main outcome measuresGood practice recommendations based on published evidence and the experience of prescribers in Scotland.ResultsThe findings of 88 uncontrolled, observational studies of variable quality were considered alongside a survey of over 200 prescribers. No national or international guidelines were identified. Antibiotic use towards the end of life was common but practice was highly variable. The potential harms associated with giving antibiotics tended to be less well considered than the potential benefits. Antibiotics often extended the length of time to death but this was sometimes at the cost of higher symptom burden. There was strong consensus around the importance of effective communication with patients and their families and making treatment decisions aligned to a patient’s goals and priorities.ConclusionsGood practice recommendations were agreed with focus on three areas: making shared decisions about future care; agreeing clear goals and limits of therapy; reviewing all antibiotic prescribing decisions regularly. These will be disseminated widely to support optimal care for patients towards the end of life. A patient version of the recommendations has also been produced to support implementation.
The enigmatic immunoglobulin G4-related disease and its varied cardiovascular manifestations
Authors: Shakir Aamina , Wheeler Yurong , Krishnaswamy Guha 
Published: January 2021

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory disease characterised by multiorgan lymphoplasmacytic infiltration, obliterative phlebitis and storiform fibrosis. It can be associated with cardiovascular pathology. The objective of this narrative review is to summarise the published literature on cardiovascular manifestations of IgG4-RD and to provide a basis for diagnosis and management of the condition by the practising cardiologist.We propose the following categorisations of cardiovascular IgG4-RD: aortitis, medium-vessel arteritis, pulmonary vascular disease, phlebitis, valvulopathy, pericarditis, myocardial disease and antineutrophilic cytoplasmic antibody-associated vasculitis. We also review herein developments in radiological diagnosis and reported medical and surgical therapies. Cardiovascular lesions frequently require procedural and/or surgical interventions, such as aortic aneurysm repair and valve replacement. IgG4-RD of the cardiovascular system results in serious complications that can be missed if not evaluated aggressively. These are likely underdiagnosed, as clinical presentations frequently mimic cardiovascular disease due to more common aetiologies (myocardial infarction, abdominal aortic aneurysm and so on). While systemic corticosteroids are the mainstay of IgG4-RD treatment, biological and disease-modifying agents are becoming more widely used. Cardiologists should be aware of cardiovascular IgG4-RD as a differential diagnosis, and understand the roles of corticosteroids, disease-modifying agents and biologicals, as well as their integration with surgical approaches. There are several knowledge gaps, including diagnosis, risk factors, pathogenesis and appropriate management in Ig4-RD of the cardiovascular system. Areas lacking well-conducted randomized trials include safety of steroids in the setting of vascular aneurysms and the role of disease-modifying drugs and biological agents in patients with established cardiovascular complications of this multifaceted enigmatic disease.
Immunologically programming the tumor microenvironment induces the pattern recognition receptor NLRC4-dependent antitumor immunity
Authors: Yu Xiaofei , Liu Wenjie , Chen Shixian , Cheng Xueqian , Paez Patrick A , Sun Tuanwei , Yuan Fang , Wei Chunyan , Landry Joseph W , Poklepovic Andrew S , Bear Harry D , Subjeck John R , Repasky Elizabeth , Guo Chunqing , Wang Xiang-Yang 
Published: January 2021

BackgroundThe efficacy of cancer immunotherapy can be limited by the poor immunogenicity of cancer and the immunosuppressive tumor microenvironment (TME). Immunologically programming the TME and creating an immune-inflamed tumor phenotype is critical for improving the immune-responsiveness of cancers. Here, we interrogate the immune modulator Flagrp170, engineered via incorporation of a pathogen-associated molecular pattern (ie, flagellin) into an immunostimulatory chaperone molecule, in transforming poorly immunogenic tumors and establishing a highly immunostimulatory milieu for immune augmentation.MethodsMultiple murine cancer models were used to evaluate the immunostimulatory activity, antitumor potency, and potential side effects of Flagrp170 on administration into the tumors using a replication impaired adenovirus. Antibody neutralization and mice deficient in pattern recognition receptors, that is, toll-like receptor 5 (TLR5) and NOD like receptor (NLR) family caspase activation and recruitment domain (CARD) domain-containing protein 4 (NLRC4), both of which can recognize flagellin, were employed to understand the immunological mechanism of action of the Flagrp170.ResultsIntratumoral delivery of mouse or human version of Flagrp170 resulted in robust inhibition of multiple malignancies including head and neck squamous cell carcinoma and breast cancer, without tissue toxicities. This in situ Flagrp170 treatment induced a set of cytokines in the TME known to support Th1/Tc1-dominant antitumor immunity. Additionally, granulocyte macrophage colony-stimulating factor derived from mobilized CD8+T cells was involved in the therapeutic activity of Flagrp170. We also made a striking finding that NLRC4, not TLR5, is required for Flagrp170-mediated antitumor immune responses.ConclusionOur results elucidate a novel immune-potentiating activity of Flagrp170 via engaging the innate pattern recognition receptor NLRC4, and support its potential clinical use to reshape cancer immune phenotype for overcoming therapeutic resistance.