bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Information Theoretic Study of a Duffing Oscillator Array Reservoir Computer
Authors: Shougat Md. Raf E Ul , Li XiaoFu , Mollik Tushar , Perkins Edmon 
Published: May 2021

Abstract
Typically, nonlinearity is considered to be problematic and sometimes can lead to dire consequences. However, the nonlinearity in a Duffing oscillator array can enhance its ability to be used as a reservoir computer. Machine learning and artificial neural networks, inspired by the biological computing framework, have shown their immense potential, especially in the real-time temporal data processing. Here, the efficacy of a Duffing oscillator array is explored as a reservoir computer by using information theory. To do this, a reservoir computer model is studied numerically, which exploits the dynamics of the array. In this system, the complex dynamics stem from the Duffing term in each of the identical oscillators. The effects of various system parameters of the array on the information processing ability are discussed from the perspective of information theory. By varying these parameters, the information metric was found to be topologically mixed. Additionally, the importance of asynchrony in the oscillator array is also discussed in terms of the information metric. Since such nonlinear oscillators are used to model many different physical systems, this research provides insight into how physical nonlinear oscillatory systems can be used for dynamic computation, without significantly modifying or controlling the underlying dynamical system. To the authors' knowledge, this is the first use of Shannon's information rate for quantifying a reservoir computer of this kind, as well as the first comparison between synchronization phenomena and the computing ability of a reservoir.
Enhancing Hierarchical Multiscale Off-Road Mobility Model by Neural Network Surrogate Model
Authors: Chen Guanchu , Yamashita Hiroki , Ruan Yeefeng , Jayakumar Paramsothy , Knap Jaroslaw , Leiter Kenneth W. , Yang Xiaobo , Sugiyama Hiroyuki 
Published: May 2021

Abstract
A hierarchical multiscale off-road mobility model is enhanced through the development of an artificial neural network (ANN) surrogate model that captures the complex material behavior of deformable terrain. By exploiting the learning capability of neural networks, the incremental stress and strain relationship of granular terrain is predicted by the ANN representative volume elements (RVE) at various states of the stress and strain. A systematic training procedure for ANN RVEs is developed with a virtual tire test rig model for producing training data from the discrete-element (DE) RVEs without relying on computationally intensive full vehicle simulations on deformable terrain. The ANN surrogate RVEs are then integrated into the hierarchical multiscale computational framework as a lower-scale model with the scalable parallel computing capability, while the macroscale terrain deformation is described by the finite element (FE) approach. It is demonstrated with several numerical examples that off-road vehicle mobility performances predicted by the proposed FE-ANN multiscale terrain model are in good agreement with those of the FE-DE multiscale model while achieving a substantial computational time reduction. The accuracy and robustness of the ANN RVE for fine-grain sand terrain are discussed for scenarios not considered in training datasets. Furthermore, a drawbar pull test simulation is presented with the ANN RVE developed with data in the cornering scenario and validated against the full-scale vehicle test data. The numerical results confirm the predictive ability of the FE-ANN multiscale terrain model for off-road mobility simulations.
AB0610 NORMOCALCAEMIC HYPERPARATHYROIDISM AND BONE HEALTH – WORSE THAN ANTICIPATED?
Authors: Masieh D. , Deshpande S. , Nisar M. K. 
Published: May 2021

Background:Since the formal recognition of normocalcaemic hyperparathyroidism (nHPT) as a distinct entity in 2008, several studies have been published describing the characteristics of these individuals. Controversy exists regarding diagnostics and the role of parathyroidectomy in such cases. A chief reason for lack of consensus is the disagreement among experts regarding the potential complications and a bias towards perhaps benign nature of this condition.Objectives:In order to understand the challenges posed by this cohort, we aim to characterise these patients at presentation to our metabolic bone diseases unit with a focus on bone health.Methods:We interrogated our departmental database and undertook retrospective analysis of all patients presenting to metabolic bone service at our large university teaching hospital with a catchment population of 350,000. Individuals were included in the survey based on criteria of Vit D >70 nmol/L, normal calcium (2.20-2.60 mmol/L), eGFR>60ml/min and PTH >6.9 pmol/L measured twice at least three months apart.Results:Over six months review period, of 134 referrals, 42 (31%) were identified with nHPT. Follow up duration was two years. Mean age was 60 years (25-86). 38 (90%) were women with 31 (81%) post menopause. 34 (80%) were of Caucasian descent. All had comorbidities with median of five (1-14). Polypharmacy (>4 prescribed medicines) was common (36/42, 85%) with mean of seven prescribed medications (0-22). Mean Vit D was 88 (70.4-133.6), calcium 2.43 (2.26-2.58), creatinine 69.8 (48-115) and PTH 8.8 (7.2-14.2). Ten (24%) had already had fragility fractures with mean of two (0-4). 21 had DXA scan with mean T score of -3.78 (-2.1 - -6.0). 13/21(31%) had osteoporosis. Oral and IV bisphosphonates, denosumab and teriparatide were prescribed to 12 (28.5%), 14 (33%), 4 (10%) and one patient respectively.Conclusion:Our study suggests high prevalence of nHPT among patients referred to metabolic bone service with confirmed bone health issues. Nearly a third of patients have nHPT in this secondary care setting and a quarter have already suffered fragility fractures. These patients carry high comorbidity, polypharmacy and osteoporosis burden. Management of such patients is challenging owing to complex interplay of various ailments. Bone active agents are required for nearly two-thirds of this group. Though the natural course of nHPT is an area of active research, our data adds to the growing body of evidence that this is not a benign condition with particularly high fracture burden and poor bone quality. nHPT is perhaps responsible for the onset and progression of the similar osseous complications as described in classical PHPT. Further longitudinal studies are required to help devise best management plan to mitigate against the skeletal encumbrance of nHPT.Disclosure of Interests:None declared.
AB0611 OSTEOPOROSIS IN RHEUMATOID ARTHRITIS: A NECESSARY EVIL?
Authors: Athimni S. , Bouden S. , Ben Tekaya A. , Dghais A. , Saidane O. , Tekaya R. , Mahmoud I. , Abdelmoula L. 
Published: May 2021

Background:Rheumatoid arthritis (RA) is a chronic inflammatory disease that is characterized by local and general bone loss. Osteoporosis (OP) is one of the most frequent comorbidities associated with RA. Many factors are incriminated in bone loss in RA such as inflammation, glucocorticoid (GC) use, and immobility.Objectives:-To determine the prevalence of OP in a population of actual RA patients.-To determine the risk factors of bone mineral density (BMD) reductionMethods:One hundred-fifty-two RA followed in the rheumatology department between 2015-2020 were enrolled in the study. The diagnosis of RA was established according to the American College of rheumatology/European League Against Rheumatism (ACR/EULAR) criteria 2010. BMD in lumbar spine and total hip was systematically measured in the recruited patients. Measures were taken with dual-energy x-ray absorptiometry (DEXA), and age-specific values were compared with pooled values from a local population of healthy subjects free from earlier fractures.Results:The mean age was 42.7±13 years. The sex ratio M/F was 0.24. The mean onset disease was 6±1.8 years. Fifty-sex patients (36.3%) were receiving conventional treatment DMARDs and 96 (63.6%) were under biological treatment. 35.5% were taken steroids with mean doses at 7.7±3.3mg/day. RF and ACPA were positive respectively in 87.3% and 82.4% of the patients. The mean disease activity score DAS28CRP was 4.8 ±2.7.Sixty-eight point eight 68.8% of the RA population had bone loss: 37.5% had osteopenia and 31.3% had OP. Regarding the OP group, sex ratio M/F was 0.45. The mean age was 42±5.3 years. Among the 31 women, 77.4% had postmenopausal OP. The BMI average was 31.18 ± 6.19 kg/m2. Fifteen patients (33.33%) had OP in the hip site and 20 patients had OP in the lumbar site (48.8%). Ten patients had both trabecular and cortical OP.Advanced age, glucocorticoid use and high DAS28CRP were independent risk factors for OP (respectively p=0.04, p=0.02 and p=0.01). Body mass index, smoking, disease duration high Health Assessment Questionnaire (HAQ) score (p=0.545) and smoking (p=0.326) were not associated with high risk of OP. The biological treatment was not a protective factor in OP (p=0.972). All the population subjects were free from earlier fractures, the fractural risk estimated by dint of the mean FRAXTM score was at 1.4 ± 2.3.Conclusion:Previous studies estimated that, approximately, osteoporosis affected one-third of RA patients which is in concordance with our study. Advanced age, glucorticoid treatment and severe disease were the most common risk factor in our study.Disclosure of Interests:None declared.
AB0768 NEUROLOGICAL MANIFESTATIONS IN GRANULOMATOSIS WITH POLYANGIITIS: ABOUT 11 CASES
Authors: Jomaa O. , Berriche O. , Arfa S. , Fraj A. , Belkhiri M. , Makhloufi R. , Romdhane W. , Hermassi M. 
Published: May 2021

Background:Granulomatosis with polyangiitis (GPA) is a rare systemic vasculitis, affecting mainly the superior airways, lungs and kidneys. Neurological impairment is frequent, described in 22 to 54% of cases, and rarely inaugurates the disease.Objectives:The objective of our work was to evaluate its prevalence and its different aspects.Methods:A retrospective study including 11 files of GPA patients followed over a period of 10 years in The Internal Medecine Department at Tahar Sfar Hospital Mahdia TUNISIA.Results:Neurological manifestations were reported in 5 patients: a pyramidal syndrome was noted in 3 patients with a normal cerebral MRI, a disabled headache was described in one patient with a normal cerebral MRI. Peripheral neuropathy in 2 cases, and the Electroneuromyogram objectified a mononeuropathy affecting the ulnar nerve, peroneal nerve, and musculocutaneous nerve in one patient and a distal sensitivomotor poly neuropathy in one patient. Cranial nerves damage was noted in two cases, one VII (1 case) and one V (1 case).Conclusion:Our study results, show the importance of timely diagnosis of these neurological manifestations, as their evolution will depend on the early GPA treatment.References:[1]doi: 10.1016/j.autrev.2017.07.007Disclosure of Interests:None declared
AB0614 DENSITOMETRIC VERTEBRAL FRACTURE ASSESSMENT: FACTORS LIMITING GOOD VISIBILITY OF THE VERTEBRA
Authors: Mariem S. , Yasmine M. , Miladi S. , Fazaa A. , Frigui E. , Souebni L. , Ouenniche K. , Kassab S. , Chekili S. , Ben Abdelghani K. , Laatar A. 
Published: May 2021

Background:The radiograph of the spine is the gold standard for identifying vertebral fractures (VF). Vertebral Fracture Assessment (VFA) is a new feature available on modern densitometers that could assess VF. This technique offers the advantage of low irradiation over standard radiography but at the cost of lower image quality.Objectives:The aim of this study was to assess factors associated with good vertebra visibility when using VFA.Methods:This is a cross-sectional study including patients referred by their physicians for bone mineral density (BMD) measurement. Anthropometric data were recorded. BMD was measured using standard methods over the lumbar spine L1-L4, the total proximal femur. Results were expressed as T-scores using Dual-energy X-ray absorptiometry (DEXA). The screening for VF was performed by VFA. A professional operator analyses VFA scans and assessed the good visibility of the vertebra.Results:The study included 100 patients. The mean age was 61.7 ±12.6 years [18-83].The average body mass index (BMI) was 28.9 ± 24.2 kg/m2 [14.2-45.3]. The mean T-score at the vertebral site was -1.5 DS [-4.9-1.5] with a mean mass of 0.95g/cm2 [0.58-1.371]. Osteoporosis was found in 27.7 % of patients. A vertebral fracture was diagnosed in 25% of cases. The visualization of the vertebra was impaired in the upper thoracic region in 60% of cases. Poor visibility was observed in 19% of cases in the mid-thoracic spine and only in 2% of cases in the lumbar spine. No statistically significant correlation was found between good vertebral visibility and age (p=0.2), weight (p=0.5), or BMI (p=0.7). However, good visibility of the vertebra was associated with a lower height (1.7 m vs 1.5 m, p=0.03). A better vertebrae visualization was correlated neither to the BMD of the right hip (0.84 vs 0.87, p=0.4) nor to the left hip (0.85 vs 0.89, p= 0.3). Similarly, the absence of vertebral osteoporosis was not correlated with a better vertebral visualization (p=0.6).Conclusion:Visibility of the vertebra on VFA does not appear to be altered by the BMD and vertebral osteoporosis, suggesting safe use in the elderly. However, precautions may be taken when interpreting VFA in patients with high heights.Disclosure of Interests:None declared.
The evolution of parents’ beliefs about childhood cancer during diagnostic communication: a qualitative study in Guatemala
Authors: Graetz Dylan , Rivas Silvia , Fuentes Lucia , Cáceres-Serrano Ana , Ferrara Gia , Antillon-Klussmann Federico , Metzger Monika , Rodriguez-Galindo Carlos , Mack Jennifer W 
Published: May 2021

IntroductionFatalistic cancer beliefs may contribute to delayed diagnosis and poor outcomes, including treatment abandonment, for children with cancer. This study explored Guatemalan parents’ cancer beliefs during initial paediatric cancer communication, and the sociocultural and contextual factors that influence these beliefs.MethodsTwenty families of children with cancer were included in this study. We audio-recorded psychosocial conversations with psychologists and diagnostic conversations with oncologists, then conducted semi-structured interviews with parents to explore the evolution of their cancer beliefs. Audio-recordings were transcribed and translated from Spanish into English, with additional review in both languages by bilingual team members. All 60 transcripts were thematically analysed using a priori and novel codes.ResultsGuatemalan parents’ beliefs evolve as they learn about cancer through various sources. Sources of information external to the cancer centre, including prior experiences with cancer, media exposure, community discussion and clinical encounters, contribute to pre-existing beliefs. Many parents’ pre-existing cancer beliefs are fatalistic; some are influenced by Mayan spirituality. Sources internal to the cancer centre include psychologists and oncologists, other providers, other patients and families. Psychologists acknowledge pre-existing beliefs and deliver cancer education using verbal explanations and hand-drawings. Oncologists provide diagnostic information and outline treatment plans. Both support hope by providing a path toward cure. Parents’ lived experience is a culmination of sources and simultaneously independent. Ultimately most parents arrive at an understanding of cancer that is consistent with an allopathic medical model and offers optimism about outcomes.ConclusionAn interdisciplinary communication process that includes cancer education, is attentive to pre-existing beliefs, and supports hope may encourage acceptance of the allopathic medical model and need for treatment. Providers in settings of all resource levels may be able to use these techniques to support cross-cultural cancer communication, reduce treatment abandonment and improve therapy adherence.
Safe opioid prescribing: a prognostic machine learning approach to predicting 30-day risk after an opioid dispensation in Alberta, Canada
Authors: Sharma Vishal , Kulkarni Vinaykumar , Eurich Dean T , Kumar Luke , Samanani Salim 
Published: May 2021

ObjectiveTo develop machine learning models employing administrative health data that can estimate risk of adverse outcomes within 30 days of an opioid dispensation for use by health departments or prescription monitoring programmes.Design, setting and participantsThis prognostic study was conducted in Alberta, Canada between 2017 and 2018. Participants included all patients 18 years of age and older who received at least one opioid dispensation. Pregnant and cancer patients were excluded.ExposureEach opioid dispensation served as an exposure.Main outcomes/measuresOpioid-related adverse outcomes were identified from linked administrative health data. Machine learning algorithms were trained using 2017 data to predict risk of hospitalisation, emergency department visit and mortality within 30 days of an opioid dispensation. Two validation sets, using 2017 and 2018 data, were used to evaluate model performance. Model discrimination and calibration performance were assessed for all patients and those at higher risk. Machine learning discrimination was compared with current opioid guidelines.ResultsParticipants in the 2017 training set (n=275 150) and validation set (n=117 829) had similar baseline characteristics. In the 2017 validation set, c-statistics for the XGBoost, logistic regression and neural network classifiers were 0.87, 0.87 and 0.80, respectively. In the 2018 validation set (n=393 023), the corresponding c-statistics were 0.88, 0.88 and 0.82. C-statistics from the Canadian guidelines ranged from 0.54 to 0.69 while the US guidelines ranged from 0.50 to 0.62. The top five percentile of predicted risk for the XGBoost and logistic regression classifiers captured 42% of all events and translated into post-test probabilities of 13.38% and 13.45%, respectively, up from the pretest probability of 1.6%.ConclusionMachine learning classifiers, especially incorporating hospitalisation/physician claims data, have better predictive performance compared with guideline or prescription history only approaches when predicting 30-day risk of adverse outcomes. Prescription monitoring programmes and health departments with access to administrative data can use machine learning classifiers to effectively identify those at higher risk compared with current guideline-based approaches.
Changes in daily mental health service use and mortality at the commencement and lifting of COVID-19 ‘lockdown’ policy in 10 UK sites: a regression discontinuity in time design
Authors: Bakolis Ioannis , Stewart Robert , Baldwin David , Beenstock Jane , Bibby Paul , Broadbent Matthew , Cardinal Rudolf , Chen Shanquan , Chinnasamy Karthik , Cipriani Andrea , Douglas Simon , Horner Philip , Jackson Caroline A , John Ann , Joyce Dan W , Lee Sze Chim , Lewis Jonathan , McIntosh Andrew , Nixon Neil , Osborn David , Phiri Peter , Rathod Shanaya , Smith Tanya , Sokal Rachel , Waller Rob , Landau Sabine 
Published: May 2021

ObjectivesTo investigate changes in daily mental health (MH) service use and mortality in response to the introduction and the lifting of the COVID-19 ‘lockdown’ policy in Spring 2020.DesignA regression discontinuity in time (RDiT) analysis of daily service-level activity.Setting and participantsMental healthcare data were extracted from 10 UK providers.Outcome measuresDaily (weekly for one site) deaths from all causes, referrals and discharges, inpatient care (admissions, discharges, caseloads) and community services (face-to-face (f2f)/non-f2f contacts, caseloads): Adult, older adult and child/adolescent mental health; early intervention in psychosis; home treatment teams and liaison/Accident and Emergency (A&E). Data were extracted from 1 Jan 2019 to 31 May 2020 for all sites, supplemented to 31 July 2020 for four sites. Changes around the commencement and lifting of COVID-19 ‘lockdown’ policy (23 March and 10 May, respectively) were estimated using a RDiT design with a difference-in-difference approach generating incidence rate ratios (IRRs), meta-analysed across sites.ResultsPooled estimates for the lockdown transition showed increased daily deaths (IRR 2.31, 95% CI 1.86 to 2.87), reduced referrals (IRR 0.62, 95% CI 0.55 to 0.70) and reduced inpatient admissions (IRR 0.75, 95% CI 0.67 to 0.83) and caseloads (IRR 0.85, 95% CI 0.79 to 0.91) compared with the pre lockdown period. All community services saw shifts from f2f to non-f2f contacts, but varied in caseload changes. Lift of lockdown was associated with reduced deaths (IRR 0.42, 95% CI 0.27 to 0.66), increased referrals (IRR 1.36, 95% CI 1.15 to 1.60) and increased inpatient admissions (IRR 1.21, 95% CI 1.04 to 1.42) and caseloads (IRR 1.06, 95% CI 1.00 to 1.12) compared with the lockdown period. Site-wide activity, inpatient care and community services did not return to pre lockdown levels after lift of lockdown, while number of deaths did. Between-site heterogeneity most often indicated variation in size rather than direction of effect.ConclusionsMH service delivery underwent sizeable changes during the first national lockdown, with as-yet unknown and unevaluated consequences.
Percutaneous radiofrequency treatment of the gasserian ganglion for trigeminal neuralgia complicated by trochlear nerve palsy: a case report
Authors: Smulders Pascal SH , Terheggen Michel AMB , Geurts José W , Kallewaard Jan Willem 
Published: May 2021

BackgroundTrigeminal neuralgia (TN) has the highest incidence of disorders causing facial pain. TN is provoked by benign stimuli, like shaving, leading to severe, short-lasting pain. Patients are initially treated using antiepileptic drugs; however, multiple invasive options are available when conservative treatment proves insufficient. Percutaneous radiofrequency treatment of the trigeminal, or gasserian, ganglion (RF-G) is a procedure regularly used in refractory patients with comorbidities. RF-G involves complex needle maneuvering to perform selective radiofrequency heat treatment of the affected divisions. We present a unique case of cranial nerve 4 (CN4) paralysis after RF-G.Case presentationA male patient in his 60s presented with sharp left-sided facial pain and was diagnosed with TN, attributed to the maxillary and mandibular divisions. MRI showed a vascular loop of the anterior inferior cerebellar artery without interference of the trigeminal complex. The patient opted for RF-G after inadequate conservative therapy. The procedure was performed by an experienced pain physician and guided by live fluoroscopy. The patient was discharged without problems but examined the following day for double vision. Postprocedural MRI showed enhanced signaling between the trigeminal complex and the brainstem. Palsy of CN4 was identified by a neurologist, and spontaneous recovery followed 5 months after the procedure.ConclusionsMention of postprocedural diplopia in guidelines is brief, and the exact incidence remains unknown. Different mechanisms for cranial nerve (CN) palsy have been postulated: incorrect technique, anatomical variations, and secondary heat injury. We observed postprocedural hemorrhage and hypothesized that bleeding might be a contributing factor in injury of CNs after RF-G.