Search

This paper presents a direct model predictive control (MPC) method for drive systems with superior steady-state and dynamic performance. Specifically, the discussed MPC algorithm achieves a steady-state behavior that is similar or better than that of a linear controller with a dedicated modulator, and fast transient responses that characterize direct controllers. Moreover, it ensures a fixed switching frequency by allowing for one switching transition per phase and sampling interval. Furthermore, the controller utilizes the stator current gradient to predict the evolution of the drive system within the prediction horizon. To find the optimal switching time instants-and thus ensure favorable performance-the control and modulation problems are formulated in one computational stage as a constrained quadratic program (QP). To solve the latter within a few microseconds, a computationally efficient QP solver based on a gradient method is proposed that enables the real-time implementation of the presented algorithm. To further alleviate the computational demands of the proposed method, a mechanism that can identify suboptimal switching sequences at the very early stages of the optimization process is proposed. The effectiveness of the proposed control scheme is experimentally verified on a 3 kW drive system consisting of a two-level inverter and an induction machine. acceptedVersion

Objective Elective surgery came to a standstill during the first wave of COVID-19. The safe resumption of elective surgery with COVID-19 prevalent in the community remains a significant challenge. The aim of this study was to look into the outcomes of elective general surgery in a dedicated 'Green Zone (GZ)' during the second wave of COVID-19 in the United Kingdom. Method A 'Green Zone' pathway, meant to provide a COVID-free environment, was created. A retrospective review of prospectively collected data was done on consecutive patients who underwent an elective general surgical procedure at a single NHS trust over a six-month period (September 1, 2020, to February 28, 2021). The primary outcome was 30-day COVID-19 mortality. Secondary outcomes included 30-day non-COVID-19 mortality, readmissions, and complications. Results The study included 331 patients with a median age of 55 years (interquartile range, IQR, 41-67); 169 (51%) were females. The majority of the patients were American Society of Anaesthesiologists grade 2 (ASA 2; n=177, 53%) followed by ASA 3 (n=76, 23%). Forty-seven patients (14%) had been shielding earlier in the year. Most of the cases were day cases (n=224, 67%). There was no 30-day COVID-19 or non-COVID-19 mortality. One patient developed COVID-19 three weeks after the index operation. Thirty-day readmission and complication rate were 4% (n=14) and 6% (n=21). Most of the complications were Clavien-Dindo grade 2 (n=10, 3%) followed by an equal number of grades 1 and 3b (n=5, 1.5%). Conclusion This study has shown that a dedicated 'Green Zone' elective operating pathway is safe and feasible provided a balanced risk assessment approach is adopted.

Long-horizon direct model predictive control (MPC) has pronounced computational complexity and is susceptible to parameter mismatches. To address these issues, this paper proposes a solution that enhances the robustness of long-horizon direct MPC, while keeping its computational complexity at bay. The former is achieved by means of a suitable prediction model of the drive system that enables the effective estimation of the total leakage inductance of the machine. For the latter, the objective function of the MPC problem is formulated such that, even though the drive behavior is computed over a long prediction interval, only a few changes in the candidate switch positions are considered. The effectiveness of the proposed approach is demonstrated with a medium-voltage (MV) drive consisting of a three-level neutral point clamped (NPC) inverter and an induction machine (IM). acceptedVersion

ObjectiveΤo report outcomes of breakthrough COVID-19 in comparison with COVID-19 in unvaccinated patients with systemic rheumatic diseases (SRDs).MethodsPatients with SRD with COVID-19 (vaccinated and unvaccinated) were included by their rheumatologists in a registry operated by the Greek Rheumatology Society in a voluntarily basis. Type, date and doses of SARS-CoV-2 vaccines were recorded, and demographics, type of SRD, concurrent treatment, comorbidities and COVID-19 outcomes (hospitalisation, need for oxygen supplementation and death) were compared between vaccinated and unvaccinated patients.ResultsBetween 1 March 2020 and 31 August 2021, 195 patients with SRD with COVID-19 were included; 147 unvaccinated and 48 vaccinated with at least one dose of a SARS-CoV-2 vaccine (Pfizer n=38 or AstraZeneca n=10). Among vaccinated patients, 29 developed breakthrough COVID-19 >14 days after the second vaccine dose (fully vaccinated), while 19 between the first and ConclusionsVaccinated patients with SRD with breakthrough COVID-19 have better outcomes compared with unvaccinated counterparts with similar disease/treatment characteristics.

Objective To describe the rate and type of adverse effects (AEs) and the frequency of disease flares after COVID-19 vaccination and to assess the reasons for vaccination hesitancy (non-vaccination) in SRD patients. Methods Telephone interviews were conducted of SRD patients consecutively enrolled (15/06/2021-1/7/2021). Participants were asked about the type of AEs and disease flare after vaccination. Reasons for vaccination hesitancy were recorded. Univariate and mutivariable analyses examined associations of demographic, clinical and other features, with occurrence of AEs, disease flare and non-vaccination. For the latter, association with negative vaccination behaviour (not influenza vaccinated for the last 2 years) and nocebo-prone behaviour (denoting AEs attributed to negative expectations [Q-No questionnaire]) was also tested. Results 561 out of 580 contacted patients were included in the study. 441/561 (78.6%) patients were vaccinated [90% (Pfizer, Moderna), 10% (Astra-Zeneca)]. AEs were reported by 148/441 (33.6%), with rates being comparable between the three vaccines. AEs were more common in females and those with chronic obstructive pulmonary disease [OR, 95% CI; females: 2.23 (1.30-3.83); COPD: 3.31 (1.24-8.83)]. Disease flare was reported in 9/441 (2%) patients. For those unvaccinated, fear that the vaccine would be harmful (53.3%), could cause disease flare (24.2%) and/or could cause thrombosis (21.7%) were the main reasons to do so. Multivariable analysis identified as independent variables for non-vaccination: nocebo-prone behaviour (OR; 95% CI, 3.88; 1.76-8.55), negative vaccination behaviour (6.56; 3.21-13.42) and previous COVID-19 infection (2.83; 1.13-7.05). Higher educational status was protective (0.49; 0.26-0.92). Conclusion No new safety signals for COVID-19 vaccination were observed. Vaccination campaign should target SRD patients with nocebo-prone and negative influenza vaccination behaviour.

This paper deals with the implementation of a long-horizon finite control set model predictive control (FCS-MPC) algorithm on an embedded system. The targeted application is a medium voltage drive system implying a very low switching frequency. The implementation is facilitated by the use of a high level synthesis (HLS) tool, which synthesizes C++ code into VHDL, enabling a higher level of abstraction and faster prototype development. Experimental results based on a small-scale prototype, consisting of a three-level neutral point clamped (NPC) inverter and an induction machine, confirm that the algorithm can be executed in real time within the targeted control period of 25μs. This allows for high switching granularity, and thus favorable steady-state and transient performance. acceptedVersion

Aim The landmark case of Montgomery v Lanarkshire Health Board led to the defensive Bolam test being discredited and paved the way healthcare professionals (HCP) obtain informed consent. The recent GMC guidance on Decision Making and Consent 2020, states that the HCP should discuss recognised risks that they believe anyone in the patient’s position would want to know. Laparoscopic cholecystectomy is one of the most common general surgical procedures performed in the UK. Chronic diarrhoea is a well-recognised complication with significant impact on patient quality of life (QoL). We aimed to assess quality of consent forms for laparoscopic cholecystectomies with emphasis on documentation of chronic diarrhoea being a consequence of the procedure. Method A retrospective review of all elective laparoscopic cholecystectomy consent forms over a 2-month consecutive period from July 1st 2020 to August 31st 2020 was carried out. Results 43 consent forms were audited. The majority of these consent forms were done by consultants (74.4%: 32/43) while 23.2% (10/43) by registrars. Overall, 39.5% (17/43) of patients were consented for experiencing chronic diarrhoea. Registrars more commonly mentioned diarrhoea (60%: 6/10) compared to consultants (31.2%: 10/32). Conclusions The majority of patients undergoing laparoscopic cholecystectomy are not consented for post-cholecystectomy diarrhoea which is a significant QoL-altering complication. Education combined with a standardised consent form and issuing of patient leaflets will improve consenting for chronic diarrhoea.

To assess the possible impact conferred by co-existing variants in MEditerranean FeVer (MEFV) and other genes on systemic autoinflammatory disease (SAID) phenotype.Consecutive patients (n = 42) who underwent screening for SAIDs by next generation sequencing (NGS) targeting 26 genes, and carried at least one MEFV gene variant, were retrospectively studied. A total of 63 MEFV gene variants mainly located in exon 10 (n = 29) and exon 2 (n = 19) were identified in 21 patients with juvenile- and 21 with adult-onset disease.The candidate clinical diagnosis was Familial Mediterranean Fever (FMF) in 11, polygenic SAIDs (PFAPA, Still's disease, atypical SAPHO and inflammatory bowel disease) in 9, whereas the disease could not be clinically defined in 22 patients. Notably, 33 out of the 42 patients (79%) had at least one co-existing variants in 19 genes other than MEFV. NGS confirmed all clinical diagnoses and helped defining diagnosis in 59% of the remaining cases. Patients with undefined SAIDs (n = 9) or atypical FMF phenotype (n = 12) carried significantly more disease-causing variants in genes other than MEFV compared to patients with typical FMF (n = 9). More than one variants in these genes were significantly associated with adult-onset disease, while disease-causing variants in the same genes were also associated with an overall more severe SAID phenotype.Co-existing variants in SAID-related genes may explain the phenotypic variability of these diseases. Further studies should validate combined molecular and clinical data in order to better understand the cumulative gene dosage effect and improve the classification of these patients.

In this paper we present a branch-and-bound algorithm that facilitates the real-time implementation of long-horizon finite control set model predictive control (FCS-MPC) for high-power electronic systems. To achieve this, the optimization process is modified such that the more likely candidates (i.e., the switching sequences with less switching transitions) are explored first. By doing so, computational demanding operations can be efficiently pipelined in a field-programmable gate array (FPGA), rendering the proposed method computationally feasible. The effectiveness of the introduced method is tested both in an FPGA-in-the-loop simulation and with a real-world setup based on a scaled-down low-voltage variable speed drive system consisting of a three-level neutral point clamped inverter and an induction machine. As shown, a real-time implementation with horizon length of twelve is achieved without sacrificing optimality. acceptedVersion

This paper presents a flux linkage-based direct model predictive current control approach that achieves favorable performance both during steady-state and transient operation. The former is achieved by computing the optimal time instants at which a new switch position is applied to the converter. To this end, the future current behavior is not computed based on the machine inductances or inductance look-up tables; instead, flux linkage maps are utilized to predict the trajectory of the magnetic flux linkage, and subsequently of the current. This is advantageous for electric drives with noticeable magnetic nonlinearity in terms of saturation and/or cross-coupling effects. Hence, by using flux linkage maps in the prediction process, the evolution of the stator current can be calculated more accurately, enabling the controller to make better switching decisions. Moreover, the discussed predictive controller exhibits excellent dynamic performance owing to its direct control nature, i.e., the control and modulation tasks are performed in one computational stage rendering a dedicated modulation stage redundant. Three different drive systems based on permanent magnet synchronous motors (PMSMs) are examined to demonstrate the effectiveness of the presented control approach. acceptedVersion

This paper presents a finite control set model predictive control (FCS-MPC) method that improves the performance of a synchronous reluctance machine drive. As shown, when a high sampling-to-switching frequency ratio is used with FCS-MPC, the stator current distortions can be significantly reduced, allowing for less losses in the machine. Moreover, the FCS-MPC steady-state performance is enhanced by introducing an integrating element into the cost function to ensure accurate output reference tracking. Finally, the adopted drive model that relies on an identified accurate magnetic model of the machine further improves the robustness of the discussed control scheme. The presented simulation and preliminary experimental results verify the effectiveness of the discussed method. acceptedVersion

New onset or exacerbation of pre-existing psoriasis after therapeutic TNF-α inhibition is a well-described phenomenon. Over the last two decades, similar cases of paradoxical psoriasis have been reported following the administration of other biologic agents. We aimed to review all published cases of induced or exacerbated psoriasis after biologic therapy other than anti-TNF-α agents in order to further elucidate the pathophysiology of this phenomenon. A systematic literature review in the Medline database regarding any relevant case series or case reports on new onset or exacerbation of psoriasis after the administration of biologic agents targeting B cells, T cell co-stimulation, interleukin-1, interleukin-6, interleukin-17 and interleukin-12/23 was performed using appropriate key words. The literature search revealed nine articles (nine cases) of paradoxical psoriasis after ustekinumab and eight articles (nine cases) after secukinumab administration, both of which are approved therapies for psoriasis Moreover, 15 articles (23 cases) for rituximab, nine articles (12 cases) for abatacept, eight articles (nine cases) for tocilizumab, and one case report for anakinra have been published. In the majority of cases, patients had no prior history of psoriasis while 18 patients presented with exacerbation of pre-existing psoriatic lesions. Paradoxical psoriasis is not a specific adverse event of TNF-α inhibitors but is a possible side effect of any biologic agent interfering with the immune system. Awareness among physicians regarding early recognition is mandatory. Further clinical and experimental data are needed in order to unravel the pathophysiology of this unexpected phenomenon. © 2021, JLE/Springer.

Finite control set model predictive control (FCS-MPC) is a promising method for the control of multi-phase machines, due to its capability to directly account for nonlinearities and multiple controlled variables. To overcome the drawback of high current ripples and excitation of harmonic currents in the so-called xy-subsystem, several methods have been proposed in the literature so far. This paper proposes an MPC-based method that achieves high granularity of switching by not only switching at the discrete time steps, but also within the sampling interval. In doing so, the discussed algorithm, referred to as variable switching point current control (VSP2CC), produces low current distortions, while still keeping the advantages of conventional FCS-MPC, such as fast dynamic behavior during transients. To highlight the above, VSP2CC is applied to a six-phase permanent magnet synchronous machine (PMSM) and compared with conventional FCS-MPC and MPC that employs virtual voltage vectors (VV-MPC). acceptedVersion

In this paper we present a direct model predictive control (MPC) scheme with time-varying sampling intervals. These sampling intervals are computed based on modulation (half-)cycles, which are obtained offline and stored in a look-up table. By utilizing the optimized modulation (half-)cycles and combining control and modulation in one computational stage, the proposed direct MPC scheme achieves lower current total harmonic distortion (THD) than conventional linear controllers with a dedicated modulator, and fast transient responses that characterize direct control methods. The effectiveness of the proposed control scheme is verified on a variable speed drive system consisting of a two-level voltage source inverter and an induction machine. acceptedVersion

To assess non-compliance and potential changes in seasonal flu vaccination coverage before and during the Covid-19 pandemic in patients with autoimmune rheumatic diseases (ARDs). Consecutive patients with ARDs followed-up in 2 tertiary hospitals were telephone-interviewed (December 12–30, 2020) regarding seasonal flu vaccination during the 2019/20 and 2020/21 time periods. Self-reported disease flares that occurred after flu vaccination, as well as reasons for non-vaccination were recorded.One thousand fifteen patients were included. The rate of flu vaccination increased from 76% before to 83% during the COVID-19 pandemic (p = 0.0001). The rate of self-reported disease flares was < 1% among vaccinated patients. Reasons for not vaccination in both periods, respectively, included: ‘was not recommended by their rheumatologists’ (35.0vs.12.2%, p < 0.0001), ‘did not feel that they would have any benefit’ (36.9 vs. 32.6%), felt unsafe to do so (27.5 vs. 30.2%), or other reasons (18.9 vs. 23.8%). By multivariate analysis, age [OR = 1.03 (95% CI 1.02–1.04)] vs. [1.04 (95% CI 1.02–1.05)] and treatment with biologics [OR = 1.66 (95% CI 1.22–2.24) vs. [1.68 (95% CI 1.19–2.38)] were independent factors associated with vaccination in both periods. These findings, although are temporally encouraging, emphasize the need for continuous campaigns aiming at increasing patients’ and physicians’ awareness about the benefits of vaccination. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.

This paper presents a control scheme that combines the optimal steady-state performance of optimized pulse patterns (OPPs) with the fast dynamics of direct model predictive control (MPC). Due to inherent challenges that relate to the utilization of OPPs in a closed-loop setting, OPPs are traditionally used in slow control loops. As a result, the associated dynamic performance of the drive system is considerably poor. To overcome this, in this work, a direct MPC algorithm is employed to manipulate the OPPs in a fast, yet optimal, manner. Specifically, the MPC algorithm takes advantage of the knowledge of the stator current evolution—as described by its gradient—within the prediction horizon. Subsequently, a constrained optimization problem with a receding horizon is solved to compute the optimal modification of the offline-computed OPP such that superior steady-state and dynamic performance is achieved. The effectiveness of the proposed method is verified based on a variable speed drive system, which consists of a two-level inverter and a low-voltage induction machine. acceptedVersion

We aimed to search for laboratory predictors of critical COVID-19 in consecutive adults admitted in an academic center between 16 September 2020–20 December 2021. Patients were uniformly treated with low-molecular-weight heparin, and dexamethasone plus remdesivir when SpO2 < 94%. Among consecutive unvaccinated patients without underlying medical conditions (n = 241, 49 year-old median, 71% males), 22 (9.1%) developed critical disease and 2 died (0.8%). White-blood-cell counts, neutrophils, neutrophil-to-lymphocyte ratio, CRP, fibrinogen, ferritin, LDH and γ-GT at admission were each univariably associated with critical disease. ROC-defined cutoffs revealed that CRP > 61.8 mg/L, fibrinogen > 616.5 mg/dL and LDH > 380.5 U/L were each associated with critical disease development, independently of age, sex and days from symptom-onset. A score combining higher-than-cutoff CRP (0/2), LDH (0/1) and fibrinogen (0/1) predicted critical disease (AUC: 0.873, 95% CI: 0.820–0.926). This score performed well in an unselected patient cohort (n = 1228, 100% unvaccinated) predominantly infected by the alpha variant (AUC: 0.718, 95% CI: 0.683–0.753), as well as in a mixed cohort (n = 527, 65% unvaccinated) predominantly infected by the delta variant (AUC: 0.708, 95% CI: 0.656–0.760). Therefore, we propose that a combination of standard biomarkers of acute inflammatory response, cell death and hypercoagulability reflects the severity of COVID-19 per se independently of comorbidities, age and sex, being of value for risk stratification in unselected patients.