Finite-gap Solutions of the Vortex Filament Equation: Isoperiodic Deformations

We study the topology of quasiperiodic solutions of the vortex filament equation in a neighborhood of multiply covered circles. We construct these solutions by means of a sequence of isoperiodic deformations, at each step of which a real double point is "unpinched" to produce a new pair of branch points and therefore a solution of higher genus. We prove that every step in this process corresponds to a cabling operation on the previous curve, and we provide a labelling scheme that matches the deformation data with the knot type of the resulting filament.Comment: 33 pages, 5 figures; submitted to Journal of Nonlinear Scienc

Numerical instability of the Akhmediev breather and a finite-gap model of it

In this paper we study the numerical instabilities of the NLS Akhmediev breather, the simplest space periodic, one-mode perturbation of the unstable background, limiting our considerations to the simplest case of one unstable mode. In agreement with recent theoretical findings of the authors, in the situation in which the round-off errors are negligible with respect to the perturbations due to the discrete scheme used in the numerical experiments, the split-step Fourier method (SSFM), the numerical output is well-described by a suitable genus 2 finite-gap solution of NLS. This solution can be written in terms of different elementary functions in different time regions and, ultimately, it shows an exact recurrence of rogue waves described, at each appearance, by the Akhmediev breather. We discover a remarkable empirical formula connecting the recurrence time with the number of time steps used in the SSFM and, via our recent theoretical findings, we establish that the SSFM opens up a vertical unstable gap whose length can be computed with high accuracy, and is proportional to the inverse of the square of the number of time steps used in the SSFM. This neat picture essentially changes when the round-off error is sufficiently large. Indeed experiments in standard double precision show serious instabilities in both the periods and phases of the recurrence. In contrast with it, as predicted by the theory, replacing the exact Akhmediev Cauchy datum by its first harmonic approximation, we only slightly modify the numerical output. Let us also remark, that the first rogue wave appearance is completely stable in all experiments and is in perfect agreement with the Akhmediev formula and with the theoretical prediction in terms of the Cauchy data.Comment: 27 pages, 8 figures, Formula (30) at page 11 was corrected, arXiv admin note: text overlap with arXiv:1707.0565

Predictive Factors for Drain Placement After Laparoscopic Cholecystectomy

Purpose: Currently, surgical drainage during a laparoscopic cholecystectomy (LC) is still placed in selected patients. Evidence of the non-beneficial effect of the surgical drain comes from studies with a heterogeneous population. This preliminary study aims to identify any clinical, demographic, or intraoperative predictive factors for a surgical drain placement during LC as the first step to identify population for a prospective randomized study. Method: The study was conducted in a single referral center and academic hospital between 2014 and 2018. Patients who underwent unconverted LC were divided into two groups: Group A (drain) and Group B (no drain). We explored baseline, preoperative, intraoperative characteristics, and postoperative outcomes. Results: Between 409 patients who underwent LC: 90 (22%) patients were in Group A (drain). Age >64 years, male sex, cholecystitis, Charlson comorbidity index (CCI) ≥ 1, experienced surgeon, intraoperative technical difficulties, need for an additional trocar, operative time >60 min, and estimated blood loss >10 ml were predictive factors at univariate analysis. While at multivariate analysis, cholecystitis (odds ratio [OR]: 2.8, 95% CI:1.5–5.1; p < 0.001), CCI ≥ 1 (OR:1.9, 95% CI:1.0–3.5; p = 0.05), intraoperative technical difficulties (OR: 3.6, 95% CI:1.8–6.2; p < 0.001), need of an additional trocar (OR: 2.5, 95% CI: 1.4–4.4; p < 0.005), and estimated blood loss >10 ml (OR: 3.0, 95% CI:1.7–5.3; p < 0.0001) were predictive factors for a surgical drain placement during LC. Conclusions: This study identified predictive factors that currently drive the surgeons to a surgical drain placement after LC. Randomized prospective studies are needed to define the use of drain placement in these selected patients

Gross-Neveu Models, Nonlinear Dirac Equations, Surfaces and Strings

Recent studies of the thermodynamic phase diagrams of the Gross-Neveu model (GN2), and its chiral cousin, the NJL2 model, have shown that there are phases with inhomogeneous crystalline condensates. These (static) condensates can be found analytically because the relevant Hartree-Fock and gap equations can be reduced to the nonlinear Schr\"odinger equation, whose deformations are governed by the mKdV and AKNS integrable hierarchies, respectively. Recently, Thies et al have shown that time-dependent Hartree-Fock solutions describing baryon scattering in the massless GN2 model satisfy the Sinh-Gordon equation, and can be mapped directly to classical string solutions in AdS3. Here we propose a geometric perspective for this result, based on the generalized Weierstrass spinor representation for the embedding of 2d surfaces into 3d spaces, which explains why these well-known integrable systems underlie these various Gross-Neveu gap equations, and why there should be a connection to classical string theory solutions. This geometric viewpoint may be useful for higher dimensional models, where the relevant integrable hierarchies include the Davey-Stewartson and Novikov-Veselov systems.Comment: 27 pages, 1 figur

Endoscopic failure for foreign body ingestion and food bolus impaction in the upper gastrointestinal tract: An updated analysis in a European tertiary care hospital

Objective Harmfulness of foreign body ingestion and food bolus impaction (FBIs) varies according to geographical area, population, habits, and diet. Therefore, studies may not draw generalizable conclusions. Furthermore, data regarding FBIs management in Europe are limited and outdated. This study aimed to analyze the endoscopic management and outcomes of FBIs in an Italian tertiary care hospital to identify risk factors for endoscopic failure. Methods We retrospectively reviewed patients who underwent upper gastrointestinal endoscopy for FBIs between 2007 and 2017. Baseline, clinical, FBIs, and endoscopic characteristics and outcomes were collected and reported using descriptive statistics and logistic regression analyses. Results Of the 381 endoscopies for FBIs, 288 (75.5%) were emergent endoscopy and 135 (35,4%) included underlying upper gastrointestinal conditions. The study population included 44 pediatric patients (11.5%), 54 prisoners (15.8%), and 283 adults (74.2%). The most common type and location of FBIs were food boluses (52.9%) and upper esophagus (36.5%), respectively. While eight patients (2.1%) developed major adverse events requiring hospital admission, the remainder (97.9%) were discharged after observation. No mortality occurred. Endoscopic success was achieved in 263 of 286 (91.9%) verified FBIs endoscopies. Endoscopic failure (8.04%) was associated with age, bone, disk battery, intentional ingestion, razor blade, prisoners, and stomach in the univariate analysis. Multivariate logistic regression revealed that intentional ingestion was associated with endoscopic failure (odds ratio: 7.31; 95% confidence interval = 2.06-25.99; P = 0.002). Conclusion Endoscopy for FBIs is safe and successful, with low hospital admission rate in children, prisoners, and adults. Intentional ingestion is a risk factor of endoscopic failure

Rogue waters

In this essay we give an overview on the problem of rogue or freak wave formation in the ocean. The matter of the phenomenon is a sporadic occurrence of unexpectedly high waves on the sea surface. These waves cause serious danger for sailing and sea use. A number of huge wave accidents resulted in damages, ship losses and people injuries and deaths are known. Now marine researchers do believe that these waves belong to a specific kind of sea waves, not taken into account by conventional models for sea wind waves. This paper addresses to the nature of the rogue wave problem from the general viewpoint based on the wave process ideas. We start introducing some primitive elements of sea wave physics with the purpose to pave the way for the further discussion. We discuss linear physical mechanisms which are responsible for high wave formation, at first. Then, we proceed with description of different sea conditions, starting from the open deep sea, and approaching the sea cost. Nonlinear effects which are able to cause rogue waves are emphasised. In conclusion we briefly discuss the generality of the physical mechanisms suggested for the rogue wave explanation; they are valid for rogue wave phenomena in other media such as solid matters, superconductors, plasmas and nonlinear opticsComment: will be published in Contemporary Physic

30-day Morbidity and Mortality after Cholecystectomy for Benign Gallbladder Disease (AMBROSE): A Prospective, International Collaborative Cohort Study

Objective: This study aimed to assess 30-day morbidity and mortality rates following cholecystectomy for benign gallbladder disease and identify the factors associated with complications. Summary Background Data: Although cholecystectomy is common for benign gallbladder disease, there is a gap in the knowledge of the current practice and variations on a global level. Methods: A prospective, international, observational collaborative cohort study of consecutive patients undergoing cholecystectomy for benign gallbladder disease from participating hospitals in 57 countries between January 1 and June 30, 2022, was performed. Univariate and multivariate logistic regression models were used to identify preoperative and operative variables associated with 30-day postoperative outcomes. Results: Data of 21,706 surgical patients from 57 countries were included in the analysis. A total of 10,821 (49.9%), 4,263 (19.7%), and 6,622 (30.5%) cholecystectomies were performed in the elective, emergency, and delayed settings, respectively. Thirty-day postoperative complications were observed in 1,738 patients (8.0%), including mortality in 83 patients (0.4%). Bile leaks (Strasberg grade A) were reported in 278 (1.3%) patients and severe bile duct injuries (Strasberg grades B-E) were reported in 48 (0.2%) patients. Patient age, ASA physical status class, surgical setting, operative approach and Nassar operative difficulty grade were identified as the five predictors demonstrating the highest relative importance in predicting postoperative complications. Conclusion: This multinational observational collaborative cohort study presents a comprehensive report of the current practices and outcomes of cholecystectomy for benign gallbladder disease. Ongoing global collaborative evaluations and initiatives are needed to promote quality assurance and improvement in cholecystectomy

Time course of risk factors associated with mortality of 1260 critically ill patients with COVID-19 admitted to 24 Italian intensive care units

94noopenPurpose: To evaluate the daily values and trends over time of relevant clinical, ventilatory and laboratory parameters during the intensive care unit (ICU) stay and their association with outcome in critically ill patients with coronavirus disease 19 (COVID-19). Methods: In this retrospective–prospective multicentric study, we enrolled COVID-19 patients admitted to Italian ICUs from February 22 to May 31, 2020. Clinical data were daily recorded. The time course of 18 clinical parameters was evaluated by a polynomial maximum likelihood multilevel linear regression model, while a full joint modeling was fit to study the association with ICU outcome. Results: 1260 consecutive critically ill patients with COVID-19 admitted in 24 ICUs were enrolled. 78% were male with a median age of 63 [55–69] years. At ICU admission, the median ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2) was 122 [89–175] mmHg. 79% of patients underwent invasive mechanical ventilation. The overall mortality was 34%. Both the daily values and trends of respiratory system compliance, PaO2/FiO2, driving pressure, arterial carbon dioxide partial pressure, creatinine, C-reactive protein, ferritin, neutrophil, neutrophil–lymphocyte ratio, and platelets were associated with survival, while for lactate, pH, bilirubin, lymphocyte, and urea only the daily values were associated with survival. The trends of PaO2/FiO2, respiratory system compliance, driving pressure, creatinine, ferritin, and C-reactive protein showed a higher association with survival compared to the daily values. Conclusion: Daily values or trends over time of parameters associated with acute organ dysfunction, acid–base derangement, coagulation impairment, or systemic inflammation were associated with patient survival.openZanella A.; Florio G.; Antonelli M.; Bellani G.; Berselli A.; Bove T.; Cabrini L.; Carlesso E.; Castelli G.P.; Cecconi M.; Citerio G.; Coloretti I.; Corti D.; Dalla Corte F.; De Robertis E.; Foti G.; Fumagalli R.; Girardis M.; Giudici R.; Guiotto L.; Langer T.; Mirabella L.; Pasero D.; Protti A.; Ranieri M.V.; Rona R.; Scudeller L.; Severgnini P.; Spadaro S.; Stocchetti N.; Vigano M.; Pesenti A.; Grasselli G.; Aspesi M.; Baccanelli F.; Bassi F.; Bet A.; Biagioni E.; Biondo A.; Bonenti C.; Bottino N.; Brazzi L.; Buquicchio I.; Busani S.; Calini A.; Calligaro P.; Cantatore L.P.; Carelli S.; Carsetti A.; Cavallini S.; Cimicchi G.; Coppadoro A.; Dall'Ara L.; Di Gravio V.; Erba M.; Evasi G.; Facchini A.; Fanelli V.; Feliciotti G.; Fusarini C.F.; Ferraro G.; Gagliardi G.; Garberi R.; Gay H.; Giacche L.; Grieco D.; Guzzardella A.; Longhini F.; Manzan A.; Maraggia D.; Milani A.; Mischi A.; Montalto C.; Mormina S.; Noseda V.; Paleari C.; Pedeferri M.; Pezzi A.; Pizzilli G.; Pozzi M.; Properzi P.; Rauseo M.; Russotto V.; Saccarelli L.; Servillo G.; Spano S.; Tagliabue P.; Tonetti T.; Tullo L.; Vetrugno L.; Vivona L.; Volta C.A.; Zambelli V.; Zanoni A.Zanella, A.; Florio, G.; Antonelli, M.; Bellani, G.; Berselli, A.; Bove, T.; Cabrini, L.; Carlesso, E.; Castelli, G. P.; Cecconi, M.; Citerio, G.; Coloretti, I.; Corti, D.; Dalla Corte, F.; De Robertis, E.; Foti, G.; Fumagalli, R.; Girardis, M.; Giudici, R.; Guiotto, L.; Langer, T.; Mirabella, L.; Pasero, D.; Protti, A.; Ranieri, M. V.; Rona, R.; Scudeller, L.; Severgnini, P.; Spadaro, S.; Stocchetti, N.; Vigano, M.; Pesenti, A.; Grasselli, G.; Aspesi, M.; Baccanelli, F.; Bassi, F.; Bet, A.; Biagioni, E.; Biondo, A.; Bonenti, C.; Bottino, N.; Brazzi, L.; Buquicchio, I.; Busani, S.; Calini, A.; Calligaro, P.; Cantatore, L. P.; Carelli, S.; Carsetti, A.; Cavallini, S.; Cimicchi, G.; Coppadoro, A.; Dall'Ara, L.; Di Gravio, V.; Erba, M.; Evasi, G.; Facchini, A.; Fanelli, V.; Feliciotti, G.; Fusarini, C. F.; Ferraro, G.; Gagliardi, G.; Garberi, R.; Gay, H.; Giacche, L.; Grieco, D.; Guzzardella, A.; Longhini, F.; Manzan, A.; Maraggia, D.; Milani, A.; Mischi, A.; Montalto, C.; Mormina, S.; Noseda, V.; Paleari, C.; Pedeferri, M.; Pezzi, A.; Pizzilli, G.; Pozzi, M.; Properzi, P.; Rauseo, M.; Russotto, V.; Saccarelli, L.; Servillo, G.; Spano, S.; Tagliabue, P.; Tonetti, T.; Tullo, L.; Vetrugno, L.; Vivona, L.; Volta, C. A.; Zambelli, V.; Zanoni, A

30-day Morbidity and Mortality after Cholecystectomy for Benign Gallbladder Disease (AMBROSE): A Prospective, International Collaborative Cohort Study

Objective:This study aimed to assess 30-day morbidity and mortality rates following cholecystectomy for benign gallbladder disease and identify the factors associated with complications.Background:Although cholecystectomy is common for benign gallbladder disease, there is a gap in the knowledge of the current practice and variations on a global level.Methods:A prospective, international, observational collaborative cohort study of consecutive patients undergoing cholecystectomy for benign gallbladder disease from participating hospitals in 57 countries between January 1 and June 30, 2022, was performed. Univariate and multivariate logistic regression models were used to identify preoperative and operative variables associated with 30-day postoperative outcomes.Results:Data of 21,706 surgical patients from 57 countries were included in the analysis. A total of 10,821 (49.9%), 4263 (19.7%), and 6622 (30.5%) cholecystectomies were performed in the elective, emergency, and delayed settings, respectively. Thirty-day postoperative complications were observed in 1738 patients (8.0%), including mortality in 83 patients (0.4%). Bile leaks (Strasberg grade A) were reported in 278 (1.3%) patients, and severe bile duct injuries (Strasberg grades B-E) were reported in 48 (0.2%) patients. Patient age, American Society of Anesthesiologists physical status class, surgical setting, operative approach, and Nassar operative difficulty grade were identified as the 5 predictors demonstrating the highest relative importance in predicting postoperative complications.Conclusions:This multinational observational collaborative cohort study presents a comprehensive report of the current practices and outcomes of cholecystectomy for benign gallbladder disease. Ongoing global collaborative evaluations and initiatives are needed to promote quality assurance and improvement in cholecystectomy