A generalization of the Hasse-Arf theorem

We use the theory of Harbater-Katz-Gabber curves to derive a generalization of the Hasse-Arf theorem for complete local field extensions in positive characteristic.Comment: 7 pages draft: Only main result and proof. Comments are welcom

Automorphisms of Algebraic Curves

Στην παρούσα διατριβή μελετώνται οι αυτομορφισμοί αλγεβρικών καμπυλών επί σωμάτων θετικής χαρακτηριστικής. Μετά από μια σύντομη περιγραφή μιας κλάσης καμπυλών γνωστών ως καμπύλες Harbater-Katz-Gabber αποδεικνύεται μια σειρά νέων αποτελεσμάτων για αυτές τις καμπύλες. Στη συνέχεια υπολογίζεται το κανονικό ιδεώδες μιας τέτοια καμπύλης. Στις τελευταίες παράγραφους δίνονται αποτελέσματα που αφορούν γενικές αλγεβρικές καμπύλες και σχετίζονται με το κανονικό ιδεώδες και με τη θεωρία των συζυγιών.In this dissertation automorphisms of algebraic curves in positive characteristic are studied. After a brief outline of a class of curves known as Harbater-Katz-Gabber curves, some new results regarding these curves are proven. After that the canonical ideal of such a curve is calculated. In the last paragraphs we present results concerning general algebraic curves and are related to the canonical ideal and the theory of syzygies

Goodbye Hartmann trial: a prospective, international, multicenter, observational study on the current use of a surgical procedure developed a century ago

Background: Literature suggests colonic resection and primary anastomosis (RPA) instead of Hartmann's procedure (HP) for the treatment of left-sided colonic emergencies. We aim to evaluate the surgical options globally used to treat patients with acute left-sided colonic emergencies and the factors that leading to the choice of treatment, comparing HP and RPA. Methods: This is a prospective, international, multicenter, observational study registered on ClinicalTrials.gov. A total 1215 patients with left-sided colonic emergencies who required surgery were included from 204 centers during the period of March 1, 2020, to May 31, 2020. with a 1-year follow-up. Results: 564 patients (43.1%) were females. The mean age was 65.9 ± 15.6 years. HP was performed in 697 (57.3%) patients and RPA in 384 (31.6%) cases. Complicated acute diverticulitis was the most common cause of left-sided colonic emergencies (40.2%), followed by colorectal malignancy (36.6%). Severe complications (Clavien-Dindo ≥ 3b) were higher in the HP group (P < 0.001). 30-day mortality was higher in HP patients (13.7%), especially in case of bowel perforation and diffused peritonitis. 1-year follow-up showed no differences on ostomy reversal rate between HP and RPA. (P = 0.127). A backward likelihood logistic regression model showed that RPA was preferred in younger patients, having low ASA score (≤ 3), in case of large bowel obstruction, absence of colonic ischemia, longer time from admission to surgery, operating early at the day working hours, by a surgeon who performed more than 50 colorectal resections. Conclusions: After 100 years since the first Hartmann's procedure, HP remains the most common treatment for left-sided colorectal emergencies. Treatment's choice depends on patient characteristics, the time of surgery and the experience of the surgeon. RPA should be considered as the gold standard for surgery, with HP being an exception

Infected pancreatic necrosis: outcomes and clinical predictors of mortality. A post hoc analysis of the MANCTRA-1 international study

: The identification of high-risk patients in the early stages of infected pancreatic necrosis (IPN) is critical, because it could help the clinicians to adopt more effective management strategies. We conducted a post hoc analysis of the MANCTRA-1 international study to assess the association between clinical risk factors and mortality among adult patients with IPN. Univariable and multivariable logistic regression models were used to identify prognostic factors of mortality. We identified 247 consecutive patients with IPN hospitalised between January 2019 and December 2020. History of uncontrolled arterial hypertension (p = 0.032; 95% CI 1.135-15.882; aOR 4.245), qSOFA (p = 0.005; 95% CI 1.359-5.879; aOR 2.828), renal failure (p = 0.022; 95% CI 1.138-5.442; aOR 2.489), and haemodynamic failure (p = 0.018; 95% CI 1.184-5.978; aOR 2.661), were identified as independent predictors of mortality in IPN patients. Cholangitis (p = 0.003; 95% CI 1.598-9.930; aOR 3.983), abdominal compartment syndrome (p = 0.032; 95% CI 1.090-6.967; aOR 2.735), and gastrointestinal/intra-abdominal bleeding (p = 0.009; 95% CI 1.286-5.712; aOR 2.710) were independently associated with the risk of mortality. Upfront open surgical necrosectomy was strongly associated with the risk of mortality (p < 0.001; 95% CI 1.912-7.442; aOR 3.772), whereas endoscopic drainage of pancreatic necrosis (p = 0.018; 95% CI 0.138-0.834; aOR 0.339) and enteral nutrition (p = 0.003; 95% CI 0.143-0.716; aOR 0.320) were found as protective factors. Organ failure, acute cholangitis, and upfront open surgical necrosectomy were the most significant predictors of mortality. Our study confirmed that, even in a subgroup of particularly ill patients such as those with IPN, upfront open surgery should be avoided as much as possible. Study protocol registered in ClinicalTrials.Gov (I.D. Number NCT04747990)

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity > 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI

Αυτομορφισμοί αλγεβρικών καμπυλών

In this dissertation automorphisms of algebraic curves in positive characteristic are studied. After a brief outline of a class of curves known as Harbater-Katz-Gabber curves, some new results regarding these curves are proven. In particular the canonical ideal of such a curve is calculated. In the last paragraphs we present results concerning general algebraic curves and are related to the canonical ideal and the theory of syzygies.Στην παρούσα διατριβή μελετώνται οι αυτομορφισμοί αλγεβρικών καμπυλών επί σωμάτων θετικής χαρακτηριστικής. Μετά από μια σύντομη περιγραφή μιας κλάσης καμπυλών γνωστών ως καμπύλες Harbater-Katz-Gabber προκύπτει μια σειρά νέων αποτελεσμάτων για αυτές τις καμπύλες. Στη συνέχεια υπολογίζεται το κανονικό ιδεώδες μιας τέτοιας καμπύλης. Στις τελευταίες παραγράφους δίνονται αποτελέσματα που αφορούν γενικές αλγεβρικές καμπύλες και σχετίζονται με το κανονικό ιδεώδες και με τη θεωρία των συζυγιών

Ανατομικές παραλλαγές του μείζονος θωρακικού πόρου και η χειρουργική τους σημασία στις επεμβάσεις θώρακος και τραχήλου

Ο μείζων θωρακικός πόρος αποτελεί το κυριότερο λεμφαγγείο του ανθρώπινου σώματος. Ο ρόλος του είναι να επιστρέφει το μεγαλύτερο μέρος της λέμφου στην φλεβική κυκλοφορία. Η ανατομία του έχει απασχολήσει πολλές φορές την ιατρική κοινότητα, ενώ πληθώρα μελετών και νεκροτομών έχουν διεξαχθεί προκειμένου να περιγράψουν την πορεία και τις ανατομικές παραλλαγές που εμφανίζει. Ωστόσο, τα αποτελέσματα που απορρέουν από αυτές τις εργασίες εμφανίζουν αρκετές διαφορές μεταξύ τους. Αυτό υποδεικνύει την σημασία της καλής γνώσης της ανατομίας του μείζονος θωρακικού πόρου από τους σύγχρονους χειρουργούς, καθώς η τρώση του μείζονος θωρακικού πόρου, παρότι σπάνια, είναι μία πιθανή επιπλοκή στις επεμβάσεις τραχήλου και θώρακος, η οποία μπορεί να αποβεί μοιραία για τον ασθενή, εάν δεν διαγνωσθεί έγκαιρα και δε ληφθούν τα απαραίτητα θεραπευτικά μέτρα.Major thoracic duct is the greatest lymphatic of human body. Its function is to return the biggest part of lymph to the venous circulation. Anatomy of major thoracic duct has concerned medical society many times, and lots of studies and cavaderic autopsies have been conducted in order to describe the course and anatomic variations of it. However, the results derived from these studies show many differences. Immense knowledge of anatomy of major thoracic duct is crucial for modern surgeons, since the damage of major thoracic duct, while unusual, can be a possible complication of neck and thoracic operations, which can be fatal for the patient, if the appropriate diagnosis and treatment are not conducted in time