549 research outputs found
On the non-integrability of the Popowicz peakon system
No full textWe consider a coupled system of Hamiltonian partial differential equations introduced by Popowicz, which has the appearance of a two-field coupling between the Camassa-Holm and Degasperis-Procesi equations. The latter equations are both known to be integrable, and admit peaked soliton (peakon) solutions with discontinuous derivatives at the peaks. A combination of a reciprocal transformation with Painlev\'e analysis provides strong evidence that the Popowicz system is non-integrable. Nevertheless, we are able to construct exact travelling wave solutions in terms of an elliptic integral, together with a degenerate travelling wave corresponding to a single peakon. We also describe the dynamics of N-peakon solutions, which is given in terms of an Hamiltonian system on a phase space of dimension 3N
Dynamics of conservative peakons in a system of Popowicz
No full textWe consider a two-component Hamiltonian system of partial
differential equations with quadratic nonlinearities introduced by
Popowicz, which has the form of a coupling between the Camassa-Holm and Degasperis-Procesi equations.
Despite having reductions to these two integrable partial differential equations, the Popowicz
system itself is not integrable. Nevertheless, as one of the authors showed with Irle, it admits
distributional solutions of peaked soliton (peakon) type, with the dynamics of
peakons being determined by a Hamiltonian system on a phase space of dimension .
As well as the trivial case of a single peakon (), the case is Liouville
integrable. We present the explicit solution for the two-peakon dynamics, and describe
some of the novel features of the interaction of peakons in the Popowicz system
Peakons and Persistence Properties of Solution for the Interacting System of Popowicz
No full textThis paper focuses on a two-component interacting system introduced by Popowicz, which has the coupling form of the Camassa–Holm and Degasperis–Procesi equations. Using distribution theory, single peakon solutions and several double peakon solutions of the system are described in an explicit expression. Moreover, dynamic behaviors of several types of double peakon solutions are illustrated through figures. In addition, the persistence properties of the solutions to the Popowicz system in weighted Lp spaces is considered via a large class of moderate weights
2025-05-04 Alla scoperta della musica Ucraina (Pieśni kompozytorów ukraińskich) / sopran solo
No full text4 maja 2025r. artystki z Wydziału Muzyki Uniwersytetu Rzeszowskiego: prof. dr hab. Olga Popowicz (sopran) oraz dr hab. prof. UR Agnieszka Hoszowska-Jabłońska (fortepian) wystąpiły w Kościele San Roberto Bellarino w Davoli Marina we Włoszech. Był to pierwszy z 3 koncertów z różnym repertuarem, wykonanych w regionie Calabria. Organizatorami koncertu afiliowanego przez Uniwersytet Rzeszowski były następujące podmioty: Esarcato Apostolico per i fedeli cattolici Ucraini dei rito bizantino residenti in Italia oraz Parrochia San Roberto Bellarino. W repertuarze koncertu znalazło się 13 pieśni na głos i fortepian kompozytorów ukraińskich – Mykoły Łysenki, Kyryła Stecenki i Jakiwa Stepowego. Kompozytorzy ci nazywani są „trzema klasykami ukraińskimi tworzącymi w stylu romantycznym”. Dali oni początek rozwojowi artystycznej liryki wokalnej na Ukrainie. Repertuar występu był całkowicie nieznany zgromadzonej publiczności włoskiej. Koncert prowadzony był przez konferansjera w języku włoskim, a każdy z prezentowanych utworów został poprzedzony wyczerpującym komentarzem muzykologicznym. Wydarzenie zgromadziło liczną publiczność zainteresowaną nieznaną twórczością, która żywo i z wielkim aplauzem reagowała na poszczególne utwory. Po występie odbyło się spotkanie ze słuchaczami, podczas którego wykonawczynie udzielały odpowiedzi na zadane pytania na temat muzyki ukraińskiej, jej stylistyki i charakteru. Wśród publiczności znaleźli się nauczyciele muzyki zainteresowani zastosowaniem ukraińskiej liryki wokalnej w dydaktyce. Artystki udostępniły materiały nutowe.
Program koncertu:
Mykoła Łysenko
Sadek wiśniowy koło chaty
Płoną ognie
Gdybym miała trzewiki
Udeptałam ścieżynkę
Oj sama ja, sama
Astry
Oj w polu jeziorko
Kyryło Stecenko
Pływaj, pływaj łabędziu
Stałam i słuchałam wiosnę
Wieczorna pieśń
Chciałabym pieśnią zostać
Jakiw Stepowyj
Oj trzy drogi szerokie
Zza gaju słońce wschodzi4 maja 2025r. artystki z Wydziału Muzyki Uniwersytetu Rzeszowskiego: prof. dr hab. Olga Popowicz (sopran) oraz dr hab. prof. UR Agnieszka Hoszowska-Jabłońska (fortepian) wystąpiły w Kościele San Roberto Bellarino w Davoli Marina we Włoszech. Był to pierwszy z 3 koncertów wykonanych w regionie Calabria. W repertuarze zabrzmiały pieśni kompozytorów ukraińskich – M. Łysenki, K. Stecenki, J. Stepowego. Publiczność była niezwykle zainteresowana nieznanym repertuarem. Po koncercie odbyła się dyskusja ze słuchaczami na temat ukraińskiej muzyki wokalnej
Mangement of acute cholecystitis : surgery, drainage and gallbladder aspiration
No full textBackground: Early laparoscopic cholecystectomy is considered the standard of care for patients admitted with acute cholecystitis. Nevertheless, a large proportion of patients admitted for acute cholecystitis are managed without acute surgery. The reasons for not opting on acute surgery include lack of resources, severe comorbidity, frailty, protracted history prior to admission or non-compliance with guidelines due to local routines. Even if early cholecystectomy remains the firsthand alternative for patients with acute cholecystitis, safe and effective management is needed in case this routine is not followed.Methods: For study one and two we retrospectively reviewed medical records of 1649 patients treated for acute cholecystitis in Stockholm County in the years 2003 and 2008. The aim was to study management and outcome after different treatment strategies. The primary focus for study one was to compare acute cholecystectomy with delayed surgery and for study two focus was on those treated with percutaneous cholecystostomy (PC). For study three we used the Swedish Registry for Gallstone Surgery and Endoscopic Retrograde Cholangiopancreatography (GallRiks) as well as the National patient register (NPR) to study the outcome after elective cholecystectomy for those patients treated initially conservatively for acute cholecystitis. The impact of time after discharge from hospital to elective surgery with focus on intra- and postoperative complications, bile duct injuries and leakage, operating time and surgeries completed laparoscopically was analyzed. Study four was a prospective safety feasibility pilot study of percutaneous gallbladder aspiration, (PGBA) as treatment of patients not suitable for emergency surgery. We performed PGBA on 25 high-risk patients. Study five was a retrospective review of 241 patients treated with cholecystostomy to evaluate maintenance of the cholecystostomy once in place. We studied when it is safe to remove a drainage and whether retrograde cholangiography adds to safety.Results: In study one and two we found that during the year 2003 42.9% and the year 2008 47.4% of patients were treated with acute cholecystectomy. Those receiving acute surgery tend to be younger and healthier. When adjusting for age, gender, severity of the inflammation, maximal white blood cell count and CRP we found no difference in complication rate between early and delayed surgery but in early surgery the operating time was shorter albeit with higher blood loss and delayed surgery had a lower conversion rate to open surgery. Between these groups there was no significant difference in intra- or and postoperative complication rates. In study two we found that patients treated with cholecystostomy tend to be older with higher co-morbidity and treatment with cholecystostomy for this group was a safe option with lower complication rate than for those treated with acute surgery, although with a longer hospital stay. In study three 8532 patients were divided into six different time intervals from discharge after acute cholecystitis to elective cholecystectomy. We found a reduction in the risk for cystic duct leakage and perioperative complications if surgery was performed more than 30 days after discharge and if surgery was performed more than one year after discharge there was an increased risk for bile duct injury. Study four was based on 25 high-risk patients treated with PGBA, showing that the procedure was successful in all patients, although one patient needed two aspirations. We registered one minor complication that did not require any intervention. Median hospital stay was 3 days (IQR 2-4 days). Recurrence rate of cholecystitis was 28%. In study five, 241 patients with a median age of 77 years, 82.6% with Tokyo grade 2 and 14.1 % grade 3 cholecystitis treated with cholecystostomy were included. Complications related to cholecystostomy Clavien-Dindo ≥ 2 were found in 19.5%. Recurrence rate following treatment with cholecystostomy was 12%. We found no significant difference in outcome if the drainage was removed based on clinical judgment or cholangiography finding. Time to drain removal did not have any impact on the complication rate either Management of the cholecystostomy had no impact on recurrence rate.Discussion: Although early cholecystectomy is considered the treatment of choice for acute cholecystitis, it is routinely applied. Rescue strategies should be evaluated for this patient group. PC seems to be a safe option for those with high risk for emergency surgery. We found that safety of cholecystectomy increases if performed more than 30 days after discharge after a conservatively treated cholecystitis. PGBA seems to be a safe treatment option in high-risk patients, although it should be evaluated in larger studies. A cholecystostomy can be safely removed early and performing a cholangiography does not seem to change the outcome.List of scientific papersI. Early versus delayed surgery for acute cholecystitis as an applied treatment strategy when assessed in population-based cohort. E Pieniowski, A Popowicz, L Lundell, P Gerber, U Gustafsson, H Sinabulya, K Sjödahl, A Tsekrekos, G Sandblom. Digestive Surgery. 2014;31:169-176. https://doi.org/10.1159/000363659 II. Cholecystostomy as bridge to surgery and as definitive treatment or acute cholecystectomy in patients with acute cholecystits. A Popowicz, L Lundell, P Gerber, U Gustafsson, E Pieniowski, H Sinabulya, K Sjödahl, A Tsekrekos, G Sandblom. Gastroenterology Research and Practice. 2016: 3672416. https://doi.org/10.1155/2016/3672416 III. Timing of elective cholecystectomy after acute cholecystits: a population-based register study. A Popowicz, L Enochsson, G Sandblom. World Journal of Surgery. 2023 Jan;47(1):152-161. https://doi.org/10.1007/s00268-022-06772-x IV. Percutaneous gallbladder aspiration (PGBA) as alternative management in high-risk patients with acute cholecystitis. A Popowicz, A Babiker, F Hammarqvist, G Sandblom. [Manuscript]V. Clinical management, safety and timing for removal of percutaneous cholecystostomy for acute cholecystitis. A single center cohort study. A Popowicz, H Enhager, F Hammarqvist, G Sandblom. [Manuscript]</p
Steric hindrance and structural flexibility shape the functional properties of a guanine-rich oligonucleotide
No full text: Ligand/protein molecular recognition involves a dynamic process, whereby both partners require a degree of structural plasticity to regulate the binding/unbinding event. Here, we present the characterization of the interaction between a highly dynamic G-rich oligonucleotide, M08s-1, and its target protein, human α-thrombin. M08s-1 is the most active anticoagulant aptamer selected thus far. Circular dichroism and gel electrophoresis analyses indicate that both intramolecular and intermolecular G-quadruplex structures are populated in solution. The presence of thrombin stabilises the antiparallel intramolecular chair-like G-quadruplex conformation, that provides by far the main contribution to the biological activity of the aptamer. The crystal structure of the thrombin-oligonucleotide complex reveals that M08s-1 adopts a kinked structural organization formed by a G-quadruplex domain and a long duplex module, linked by a stretch of five purine bases. The quadruplex motif hooks the exosite I region of thrombin and the duplex region is folded towards the surface of the protein. This structural feature, which has never been observed in other anti-exosite I aptamers with a shorter duplex motif, hinders the approach of a protein substrate to the active site region and may well explain the significant increase in the anticoagulant activity of M08s-1 compared to the other anti-exosite I aptamers
THE DIFFERENTIAL-ALGEBRAIC ANALYSIS OF SYMPLECTIC AND LAX STRUCTURES RELATED WITH NEW RIEMANN-TYPE HYDRODYNAMIC SYSTEMS
No full textA differential-algebraic approach to studying the Lax-type integrability of the generalized Riemann-type hydrodynamic hierarchy, proposed recently by 0. D. Artemovych, M. V. Pavlov, Z. Popowicz and A. K. Prykarpatski, is developed. In addition to the Lax-type representation, found before by Z. Popowicz, a closely related representation is constructed in exact form by means of a new differential-functional technique. The bi-Hamiltonian integrability and compatible Poisson structures of the generalized Riemann type hierarchy are analyzed by means of the symplectic and gradient-holonomic methods. An application of the devised differential-algebraic approach to other Riemann and Vakhnenko type hydrodynamic systems is presented
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