A Schur Transformation for Functions in a General Class of Domains

In this paper we present a framework in which the Schur transformation and the basic interpolation problem for generalized Schur functions, generalized Nevanlinna functions and the like can be studied in a unified way. The basic object is a general class of functions for which a certain kernel has a finite number of negative squares. The results are based on and generalize those in previous papers of the first three authors on the Schur transformation in an indefinite setting

On a new class of reproducing kernel spaces and a new generalization of the Iohvidov laws

AbstractA new class of finite dimensional reproducing kernel spaces of m × 1 vector valued analytic functions on a fairly general domain Ω+ is introduced. The reproducing kernels of these spaces have a special form which is based on an m × m matrix valued function Θ, which is J unitary on the boundary of Ω+. Every invertible Hermitian matrix can be interpreted as the Gram matrix of a suitably chosen basis in such a space, where m is equal to the appropriately defined displacement rank of the given matrix. Orthogonal decompositions of the space are developed in terms of Schur complements of the matrix and factorizations of the Θ, much as in the classical cases wherein Ω+ is either the unit disc or the half plane. Finally, a new generalization of the Iohvidov laws (which extends earlier generalizations by the same authors) is deduced as an application of the theory

Determination of hot crack susceptibility in various kinds of steels

The aim of this investigation was to study the hot crack susceptibility of some Turkish and German structural steel plates with a modified varestraint-transvarestraint test method. Testing was accomplished using a Tungsten Inert Gas (TIG) welding process. The results of this study revealed that total crack length increases as welding current increases or punch radius or welding speed decreases. An attempt is made to provide explanations for these phenomena. (C) 1997 Elsevier Science Ltd

Effects of Comorbidities on Hospitalization Costs of COVID-19 in Türkiye

Introduction: In December 2019, pneumonia associated with the 2019 novel Coronavirus or Severe acute respiratory syndrome-Coronavirus-2 emerged in Wuhan, China. Its effects on national and global economies have been tremendous. There is limited evidence regarding treatment costs for hospitals and the effects of comorbidities on treatment costs. These factors are crucial inputs for health policymakers. The main objective of this study was to retrospectively determine the direct healthcare costs of hospitalized Coronavirus disease-2019 (COVID-19) patients in Türkiye and estimate the effect of comorbidities on these costs. Materials and Methods: This study was conducted at two prominent research and training hospitals in İzmir, Türkiye, during the first year of the COVID-19 pandemic. General Linear Models were employed for the calculation of cost figures. The hospitalization costs of 2,067 patients with COVID-19 were analyzed, and the effects of comorbidities on the treatment costs of 532 patients with COVID-19 were estimated. Results: Our analysis based on the entire sample of 2,067 patients revealed that the mean hospitalization cost was $1,432.3 [purchasing power parity (PPP)$4,994.7]. The mean treatment cost is higher for male patients and increases with age and intensive care unit admissions. The mean length of hospitalization was 10.6 days [standard deviation (SD) ±8.5] and the mean length of intensive care unit hospitalization was 9.9 (SD ±9.6). The mean daily hospitalization cost was $135.25 (PPP$471.63) for 2,067 patients. Hospitalization costs for COVID-19 patients significantly increased due to factors, such as gender, age, intensive care unit hospitalization, and comorbidities, including myocardial infarction, cerebrovascular and transient ischemic attacks, chronic obstructive pulmonary disease, and chronic kidney disease, according to the analysis. Conclusion: COVID-19 is a novel pandemic that caused morbidity and mortality at considerable levels. A holistic approach to fighting the pandemic requires unraveling not only medical efforts but also financial aspects

Posttraumatic Septic Arthritis Due to Serratia marcescens: Case Report and Review of Literature

Septic arthritis is classified among the acute emergencies of joint diseases. Gram-positive cocci are responsible in 75-80% of the cases, while Gramnegative bacilli may be the etiological agents in case of compromised immunity, intravenous drug abuse, advanced age, or iatrogenic infections. Cases of posttraumatic septic arthritis due to Gram-negative bacilli in immunocompetent patients are reported in the literature. In this paper we present a severe septic arthritis due to Serratia marcescens in a 43-year-old man with multiple trauma, right patellar and femoral condyle fracture after a traffic accident, three days after an irrigation and debridement procedure was performed. The surgical procedure had to be repeated four times while he was receiving medical treatment. A literature search in PubMed using the keywords "Serratia marcescens and septic arthritis" on October 10th 2017, we found 37 articles, of which 18 were case reports or case series. Of those 18 articles, seven cases were hospital-acquired, five were in intravenous drug users, two were trauma related, one was concomitant with rheumatoid arthritis, one was in a neonate, one was due to intra-articular injection, and one article described an epidemic due to usage of contaminated benzalkonium chloride solution as an antiseptic. We also found a case by searching Turkish Medline reported in a ten-week-old baby with Escobar syndrome. In our case, although hospital-acquired infection cannot be ruled out, we believe that this was a community-acquired infection due to contamination of the open dirty wound, as the irrigation procedure was done in sterile operating room conditions and no other such case has ever been identified. As prompt diagnosis and treatment is critical in prognosis of septic arthritis, we emphasize the possible role of Gram-negative bacilli in posttraumatic cases