Boundedness character of a max-type system of difference equations of second order

The boundedness character of positive solutions of the next max-type system of difference equations $$x_{n+1}=\max\left\{A,\frac{y_n^p}{x_{n-1}^q}\right\},\quad y_{n+1}=\max\left\{A,\frac{x_n^p}{y_{n-1}^q}\right\},\quad n\in\mathbb{N}_0,$$ with $\min\{A, p, q\}>0$, is characterized

On a higher-order system of difference equations

Here we study the following system of difference equations xn = f −1 cnf(xn−2k) ∏k an + bn i=1 g(y) n−(2i−1))f(xn−2i) yn = g −1 γng(yn−2k) ∏k αn + βn i=1 f(x) n−(2i−1))g(yn−2i) n ∈ N0, where f and g are increasing real functions such that f(0) = g(0) = 0, and coefficients an, bn, cn, αn, βn, γn, n ∈ N0, and initial values x−i, y−i, i ∈ {1, 2,..., 2k} are real numbers. We show that the system is solvable in closed form, and study asymptotic behavior of its solutions

Multi-site European framework for real-time co-simulation of power systems

© The Institution of Engineering and Technology. The framework for virtual integration of laboratories enables co-simulation and joint experiments that include hardware and software resources hosted at geographically distributed laboratories. The underlying concept of such framework is geographically distributed real-time (RT) co-simulation. To this end, digital RT simulators are interfaced over long distances via shared communication network such as the Internet. This study proposes an architecture for a modular framework supporting virtual integration of laboratories that enable flexible integration of digital RT simulators across Europe. In addition, the framework includes an interface that enables access for third parties via a web browser. A co-simulation interface algorithm adopted in this study is based on representation of interface quantities in form of dynamic phasors. Time delay between RT digital simulators is compensated by means of phase shift that enables simulation fidelity for slow transients. The proposed architecture is realised for the integration of laboratories across Europe that are located at RWTH Aachen University in Germany, Politecnico di Torino in Italy and at European Commission Joint Research Centres in Petten, Netherland and in Ispra, Italy. The framework for virtual integration of laboratories presented in this study is applied for co-simulation of transmission and distribution systems

A multi-site real-time co-simulation platform for the testing of control strategies of distributed storage and V2G in distribution networks

© 2016 IEEE and EPE Association. This paper presents a real-time co-simulation platform aimed to test control strategies for the management of the interaction between a smart grid and active prosumers. The main feature of the proposed framework relies on the multi-site approach that allows the decoupling between the network model and the system under test. This allows separate testing with the exchange of a limited amount of information between the two systems, helping to preserve the confidentiality of data belonging to different parties. As an example the paper addresses the development and testing of a distributed storage and vehicle-to-grid management system connected to a real distribution network model

Virtual integration of laboratories over long distance for real-time co-simulation of power systems

© 2016 IEEE. The interest in the virtual integration of hardware and software assets located at geographically dispersed locations, although not new, has spiked recently. However, realizing joint real-time simulation in connected laboratories is posing new challenges. This paper discusses the generalized requirements of a framework for the virtual integration of laboratories and presents the architecture of the platform that integrates two real-time digital simulators (RTDS located at ACS, RWTH Aachen University, Germany, and OPAL-RT at Politecnico di Torino, Italy). The platform enables remote and online monitoring of the entire interconnected system which is a step towards developing Simulation as a Service concept. The application of this platform for real-time co-simulation of interconnected transmission and distribution systems is demonstrated

Resolving the Sources of Plasma Glucose Excursions following a Glucose Tolerance Test in the Rat with Deuterated Water and [U-13C]Glucose

Sources of plasma glucose excursions (PGE) following a glucose tolerance test enriched with [U-13C]glucose and deuterated water were directly resolved by 13C and 2H Nuclear Magnetic Resonance spectroscopy analysis of plasma glucose and water enrichments in rat. Plasma water 2H-enrichment attained isotopic steady-state within 2–4 minutes following the load. The fraction of PGE derived from endogenous sources was determined from the ratio of plasma glucose position 2 and plasma water 2H-enrichments. The fractional gluconeogenic contributions to PGE were obtained from plasma glucose positions 2 and 5 2H-positional enrichment ratios and load contributions were estimated from plasma [U-13C]glucose enrichments. At 15 minutes, the load contributed 26±5% of PGE while 14±2% originated from gluconeogenesis in healthy control rats. Between 15 and 120 minutes, the load contribution fell whereas the gluconeogenic contribution remained constant. High-fat fed animals had significant higher 120-minute blood glucose (173±6 mg/dL vs. 139±10 mg/dL, p<0.05) and gluconeogenic contributions to PGE (59±5 mg/dL vs. 38±3 mg/dL, p<0.01) relative to standard chow-fed controls. In summary, the endogenous and load components of PGE can be resolved during a glucose tolerance test and these measurements revealed that plasma glucose synthesis via gluconeogenesis remained active during the period immediately following a glucose load. In rats that were placed on high-fat diet, the development of glucose intolerance was associated with a significantly higher gluconeogenic contribution to plasma glucose levels after the load

Postoperative complications in patients undergoing thyroid surgery

Background and objectives: Postoperative complications from thyroid surgery are numerous and may be shown on different levels. Some of these complications may be detrimental for patients, so minimization of the risks should be always considered. We evaluated the postoperative complications in patients after surgery of the thyroid gland at the Clinic for Thoracic Surgery, Skopje. Material and method: In retrospective manner, all patients undergoing thyroid surgery during the one-year period (1. January- 31. December 2017) were evaluated. Patients were divided into two groups, whereas group ST included patients who underwent goiter removal and subtotal thyroidectomy while group TT included patients in who total thyroidectomy was done. In both groups we analyzed the demographic data and the occurrence of postoperative (in the first 48 hours) complications (stridor, hoarseness, hemorrhage, nerve dysfunction, tracheomalacia, hypocalcemia and the need for reintubation and tracheostomy). Results: Total data from 197 patients was evaluated. 120 patients had subtotal thyroidectomy while total thyroidectomy had 77 patients. Postoperative complications occurred in significantly larger number of patients in the TT group (64.9 vs. 40%). Hoarseness (8.4% vs. 18.5%), stridor (18.3% vs. 9.2%) tracheomalacia (5% vs. 1.2%) and hematoma (2.5% vs. 3.8%) occurred in respect to the groups. Hypocalcaemia occurred in significantly larger number of patients in TT group. Permanent nerve injury was found in one patient in the same group and tracheotomy was done only in one patient. Conclusion: Overall results from our study show that the complications after thyroid surgery occur in all patients who undergo thyroid surgery. However, more severe complications and outnumbered are complications in patients who undergo total thyroidectomy. Key words: complications, occurrence, thyroid surgery, total thyroidectomy

Clinical trials in pediatric ALS: a TRICALS feasibility study.

Background: Pediatric investigation plans (PIPs) describe how adult drugs can be studied in children. In 2015, PIPs for Amyotrophic Lateral Sclerosis (ALS) became mandatory for European marketing-authorization of adult treatments, unless a waiver is granted by the European Medicines Agency (EMA).Objective: To assess the feasibility of clinical studies on the effect of therapy in children (<18 years) with ALS in Europe.Methods: The EMA database was searched for submitted PIPs in ALS. A questionnaire was sent to 58 European ALS centers to collect the prevalence of pediatric ALS during the past ten years, the recruitment potential for future pediatric trials, and opinions of ALS experts concerning a waiver for ALS.Results: Four PIPs were identified; two were waived and two are planned for the future. In total, 49 (84.5%) centers responded to the questionnaire. The diagnosis of 44,858 patients with ALS was reported by 46 sites; 39 of the patients had an onset < 18 years (prevalence of 0.008 cases per 100,000 or 0.087% of all diagnosed patients). The estimated recruitment potential (47 sites) was 26 pediatric patients within five years. A majority of ALS experts (75.5%) recommend a waiver should apply for ALS due to the low prevalence of pediatric ALS.Conclusions: ALS with an onset before 18 years is extremely rare and may be a distinct entity from adult ALS. Conducting studies on the effect of disease-modifying therapy in pediatric ALS may involve lengthy recruitment periods, high costs, ethical/legal implications, challenges in trial design and limited information

Association of Variants in the SPTLC1 Gene with Juvenile Amyotrophic Lateral Sclerosis

Importance: Juvenile amyotrophic lateral sclerosis (ALS) is a rare form of ALS characterized by age of symptom onset less than 25 years and a variable presentation. Objective: To identify the genetic variants associated with juvenile ALS. Design, Setting, and Participants: In this multicenter family-based genetic study, trio whole-exome sequencing was performed to identify the disease-associated gene in a case series of unrelated patients diagnosed with juvenile ALS and severe growth retardation. The patients and their family members were enrolled at academic hospitals and a government research facility between March 1, 2016, and March 13, 2020, and were observed until October 1, 2020. Whole-exome sequencing was also performed in a series of patients with juvenile ALS. A total of 66 patients with juvenile ALS and 6258 adult patients with ALS participated in the study. Patients were selected for the study based on their diagnosis, and all eligible participants were enrolled in the study. None of the participants had a family history of neurological disorders, suggesting de novo variants as the underlying genetic mechanism. Main Outcomes and Measures: De novo variants present only in the index case and not in unaffected family members. Results: Trio whole-exome sequencing was performed in 3 patients diagnosed with juvenile ALS and their parents. An additional 63 patients with juvenile ALS and 6258 adult patients with ALS were subsequently screened for variants in the SPTLC1 gene. De novo variants in SPTLC1 (p.Ala20Ser in 2 patients and p.Ser331Tyr in 1 patient) were identified in 3 unrelated patients diagnosed with juvenile ALS and failure to thrive. A fourth variant (p.Leu39del) was identified in a patient with juvenile ALS where parental DNA was unavailable. Variants in this gene have been previously shown to be associated with autosomal-dominant hereditary sensory autonomic neuropathy, type 1A, by disrupting an essential enzyme complex in the sphingolipid synthesis pathway. Conclusions and Relevance: These data broaden the phenotype associated with SPTLC1 and suggest that patients presenting with juvenile ALS should be screened for variants in this gene.