(Co)-Higgs bundles on Non-K\"ahler Elliptic Surfaces

In this paper, we study Higgs and co-Higgs bundles on non-K\"ahler elliptic surfaces. We show, in particular, that non-trivial stable Higgs bundles only exist when the base of the elliptic fibration has genus at least two and use this existence result to give explicit topological conditions ensuring the smoothness of moduli spaces of stable rank-2 sheaves on such surfaces. We also show that non-trivial stable co-Higgs bundles only exist when the base of the elliptic fibration has genus 0, in which case the non-K\"ahler elliptic surface is a Hopf surface. We then given a complete description of non-trivial co-Higgs bundles in the rank 2 case; these non-trivial rank-2 co-Higgs bundles are examples of non-trivial holomorphic Poisson structures on $\mathbb{P}^1$-bundles over Hopf surfaces.Comment: Added examples and background material. Corrected an error in Proposition 5.

An essentially saturated surface not of Kaehler-type

It is shown that if $X$ is an Inoue surface of type $S_M$ then the irreducible components of the Douady space of $X^n$ are compact, for all $n>0$. This gives an example of an essentially saturated compact complex manifold (in the sense of model theory) that is not of Kaehler-type. Among the known compact complex surfaces without curves, it is shown that these are the only examples.Comment: 10 page

A vanishing theorem for T-branes

We consider regular polystable Higgs pairs $(E, \phi)$ on compact complex manifolds. We show that a non-trivial Higgs field $\phi \in H^0 ({\rm End} (E) \otimes K_S)$ restricts the Ricci curvature of the manifold, generalising previous results in the literature. In particular $\phi$ must vanish for positive Ricci curvature, while for trivial canonical bundle it must be proportional to the identity. For K\"ahler surfaces, our results provide a new vanishing theorem for solutions to the Vafa--Witten equations. Moreover they constrain supersymmetric 7-brane configurations in F-theory, giving obstructions to the existence of T-branes, i.e. solutions with $[\phi, \phi^\dagger] \neq 0$. When non-trivial Higgs fields are allowed, we give a general characterisation of their structure in terms of vector bundle data, which we then illustrate in explicit examples.Comment: 40 pages, 1 gri

Risk factors in appearance of acute appendicitis complications

Catedra de chirurgie nr. 2, Universitatea de Stat de Medicină și Farmacie „Nicolae Testemiţanu”, Chişinău, Republica Moldova, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: Apendicita acută reprezintă cea mai frecventă urgenţă chirurgicală, iar complicaţiile sale intraabdominale continuă să determine o mortalitate postoperatorie constantă. Scopul: studierea factorilor de risc ai evoluţiei complicaţiilor apendicitei acute. Material şi metode: Studiul include analiza rezultatelor tratamentului chirurgical al 449 bolnavi, operaţi în aa.2015-2017 şi divizaţi în 2 grupe: 117 pacienţi cu complicaţii ale apendicitei acute (intra- şi extraabdominale) şi 332 bolnavi cu apendicită acută necomplicată. Rezultate: În grupa cu apendicită acută complicată (AAC) s-a constatat o predominare a femeielor cu o rată de 1,60 comparativ cu 1,26 în grupa cu apendicită acută necomplicată (AAN). Rata persoanelor cu vîrstă > 60 ani a fost semnificativ mai mare în cazul AAC- 23,1%, fiind doar 3,9% în AAN. În cazul AAC s-a consemnat o tergiversare în adresare, termenul debut- adresare fiind mult mai mare comparativ cu grupa AAN. Statutul socio-economic jos a avut un impact negativ semnificativ asupra evoluţiei apendicitei acute şi complicaţiilor ei, la fel asupra rezultatelor apendicectomiei. Pacienţii neasiguraţi (n=59, 49,6%) au format practic jumătate din grupa AAC. Comorbidităţi asociate au fost stabilite în 76(16,9%) observaţii, respectiv în AAC- 21,4% vs. 15,4% în AAN. În sumar am notat, că prezenţa comorbidităţilor asociate necorijate de regulă au avut un impact negativ asupra evoluţiei apendicitei acute. Concluzii: Rezultatele noastre sugestă, că evaluările clinice sunt cele mai importante pentru identificarea persoanelor cu risc de evoluţie a complicaţiilor apendicitei acute, iar factorii de risc sus-menţionaţi sunt utili în deciziile chirurgicale de urgenţă.Background: Acute appendicitis is the most frequency surgical emergency, and its intraabdominal complications continue to determine the constant postoperative mortality. Aim of the study: To study the risk factors of the development of acute appendicitis (AA) complications. Methods and materials: The research included 449 patients with AA treated surgically during 2015-2017 divided into 2 groups: 117 patients who were admitted with complicated appendicitis (intra- and extraabdominal complications) and 332 patients with noncomplicated AA were randomly selected from the same period. Results: In the group complicated acute appendicitis (CAA), there was a predominance of women with a ratio of 1.60 versus 1.26 in the uncomplicated acute appendicitis group (NAA). The proportion of people aged > 60 years was significantly higher in the case of CAA-23.1%, while in uncomplicated AA it was only 3.9%. In the case of AA complications, there was an emphasis on late addressing, the debut-addressing term being higher compared to uncomplicated AA. The low socio-economic status has a significant negative impact on the evolution of AA and its complications, as well as on the results of apendectomy. Thus, uninsured patients (n=59, 49.6%) formed almost half of CAA group. Associated comorbidities were established in 76 or 16.9% of cases, respectively in CAA-21.4% vs 15.4% in NAA group. In summary we note that the presence of associated uncorrected comorbidities has an obvious negative impact on the development of AA. Conclusion: Our findings suggest that clinical assessment is most important for identifying individuals at risk of developing complications of AA and the above-mentioned risc factors are useful for emergency surgical decisions

Insuficiența hepatică postoperatorie - cauză semnificativă a mortalității la pacienți cu chisturi hidatice gigante complicate

Background. Giant hydatid cysts usually lead to diffuse irreversible damage to the liver, aggravating the results of surgical treatment and their presence is accompanied by high mortality. Objective of the study. Analysis of factors that predispose to the development of liver failure in patients with complicated echinococcosis Material and Methods. 347 patients with hepatic hedadidosis were operated on in the clinic between 2000 and 2020. The diagnostic algorithm included: USG, Doppler, EFGDS, CT, MRI in cholangiography regime, serological and biochemical analyzes. Results. In 33 (9.5%) cases, giant hydatid cysts located in more than 4 segments of the liver were detected. Of which, in the preoperative period, liver cirrhosis was detected in 4 (12.1%) patients, the early stage of portal hypertension was detected in 7 (21.2%), mechanical jaundice in 9 (27.3%), reactive hepatitis in 10 ( 30.3%) patients, hydatid cachexia in 3 (9.09%). Postoperative liver failure developed in 9 (27.3%) patients who underwent urgent surgery. Mortality rate - 7 (18.1%). Conclusion. Predisposing factors for the development of postoperative liver failure are as follows - large destructive lesions of the liver parenchyma, small volume of the remaining parenchyma, decreased blood supply, cachexia, old age, the presence of concomitant pathologies. Introducere. Chisturile hidatice hepatice gigante, de regulă, determină leziuni difuze ireversibile ale ficatului, agravând astfel rezultatele tratamentului chirurgical și sunt insoțite de o mortalitate înaltă. Scopul lucrării. Analiza factorilor predisponibili evoluției insuficienței hepatice la pacienții cu chisturi hidatice gigantice complicate. Material și Metode. Studiul este axat asupra 347 pacienți cu hidadidoză hepatică operați în perioada aa.2000 – 2020. Algoritmul diagnostic a inclus: USG, dopplerografie, FEGDS, CT, IMRCP în regim colangiografic, analize serologice și biochimice. Rezultate. În 33 (9.5%) cazuri au fost depistate chisturi hidatice hepatice gigante, ce au inclus mai mult de 4 segmente ale ficatului. În acest grup, preoperator s-a atestat ciroză hepatică la 4 (12.1%) pacienți, manifestări clinice ale hipertensiunii portale - la 7 (21.2%) pacienți, icter mecanic- în 9 (27.3%) cazuri, hepatită reactivă la 10 (30.3%) pacienți, cașexie hidatică la 3 (9.09%) bolnavi. Insuficiența hepatică postoperatorie a evoluat la 9 (27.3%) pacienți operați după indicații vitale. Mortalitatea generală în acest lot a constituit 7(18.1%) cazuri. Concluzii. Factorii predisponibili ai insuficienței hepatice postoperatorii în chisturile hepatice gigante sunt polimorfi, primordial fiind reprezentați de leziunile destructive voluminoase ale parenchimului hepatic cu funcționalitate redusă a parenchimului hepatic restant, hipoperfuzie arterială și portală

Two-dimensional moduli spaces of vector bundles over Kodaira surfaces

We prove that any two-dimensional moduli space of stable 2-vector bundles, in the non-filtrable range, on a primary Kodaira surface is a primary Kodaira surface. If a universal bundle exists, then the two surfaces are homeomorphic up to unramified covers.Comment: Advances in Mathematics, accepte