Cycle-finite module categories

We describe the structure of module categories of finite dimensional algebras over an algebraically closed field for which the cycles of nonzero nonisomorphisms between indecomposable finite dimensional modules are finite (do not belong to the infinite Jacobson radical of the module category). Moreover, geometric and homological properties of these module categories are exhibited

Vestibular disease in dogs: association between neurological examination, MRI lesion localisation and outcome.

OBJECTIVES To determine whether the neurological examination correctly distinguishes between central and peripheral vestibular lesions in dogs. MATERIALS AND METHODS Retrospective study on dogs with vestibular disease presenting to two referral clinics in Germany. RESULTS Ninety-three dogs were included; neurological examination suggested central vestibular disease in 62 and a peripheral lesion in 31. MRI diagnosis was central vestibular disease in 68 dogs and peripheral in 25. Of the 62 dogs with a lesion localisation diagnosed as central vestibular by neurological exam, 61 were correctly identified (98.4%). Twenty-four of the 31 dogs diagnosed with a peripheral lesion by neurological exam had a consistent lesion on MRI (77.4%). CLINICAL SIGNIFICANCE The neurological examination is efficient at identifying lesions in the central vestibular system but less so for peripheral lesions. Therefore it is prudent to recommend imaging in dogs that show signs of peripheral vestibular syndrome but do not rapidly respond to treatment

Covering functors without groups

Coverings in the representation theory of algebras were introduced for the Auslander-Reiten quiver of a representation finite algebra by Riedtmann and later for finite dimensional algebras by Bongartz and Gabriel, R. Martinez-Villa and de la Pe\~na. The best understood class covering functors is that of Galois covering functors F: A -> B determined by the action of a group of automorphisms of A. In this work we introduce the balanced covering functors which include the Galois class and for which classical Galois covering-type results still hold. For instance, if F:A -> B is a balanced covering functor, where A and B are linear categories over an algebraically closed field, and B is tame, then A is tame.Comment: Some improvements have been made; in particular, the proof of Theorem 2 has been restructured and clarifie

Low-dose intra-arterial contrast-enhanced MR aortography in patients based on a theoretically derived injection protocol

Multiple intra-arterial contrast agent injections are necessary during MR-guided endovascular interventions. In respect to the approved limits of maximum daily gadolinium dose, a low-dose injection protocol is mandatory. The objective of this study was to derive and apply a low-dose injection protocol for intra-arterial 3D contrast-enhanced MR aortography in patients. Injection rate (Qinj), concentration of injected gadolinium [Gd]inj and aortal blood flow rate (Qblood) were included for the theoretical evaluation of signal intensity (SI) of the arterial lumen. SI simulations were carried out at Qinj=2 versus 4ml/s in the [Gd]inj range between 0-500mM. Qinj and [Gd]inj with SI above the 75% threshold of the maximal SI were regarded as optimal injection parameters. [Gd]inj=50mM and Qinj=4ml/s were considered as optimal and were administered in five patients for 3D MR aortography. All images revealed clear delineation of the abdominal aorta and its major branches. Mean±SD of contrast-to-noise ratios of the abdominal aorta, common iliac and renal artery were 70.2±15.2, 58.6±12.3 and 67.4±12.3. Approximately seven intra-aortal injections would be permissible in patients during MR-guided interventions without exceeding the maximal dose of gadoliniu

The first Hochschild cohomology group of a schurian cluster-tilted algebra

Given a cluster-tilted algebra B we study its first Hochschild cohomology group HH1(B) with coefficients in the B-B-bimodule B. We find several consequences when B is representation-finite, and also in the case where B is cluster-tilted of type Ã.Fil: Assem, Ibrahim. University of Sherbrooke; CanadáFil: Redondo, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Matemática Bahía Blanca. Universidad Nacional del Sur. Departamento de Matemática. Instituto de Matemática Bahía Blanca; Argentin

Rationale Schnittbildgebung des hepatozellulären Karzinoms: Die Herausforderung multimodaler Diagnosekriterien

Zusammenfassung: Klinisches/methodisches Problem: CT und MRT bilden den Goldstandard in der bildgebenden Diagnostik des hepatozellulären Karzinoms (HCC). Beide Verfahren erlauben als alleinige Untersuchung bei entsprechendem Kontrastmittelverhalten die Diagnose eines HCC. Eine radiologische Herausforderung stellen immer noch die Detektion von HCC-Läsionen  2cm sehr hohe Detektionsraten zwischen 90 und 100 %. Für Läsionen zwischen 1 und 2cm bestehen Vorteile der MRT mit Sensitivitäten zwischen 80 und 90 % gegenüber 60-75 % der CT. Die MRT-Diagnostik profitiert neben den multimodalen Diagnosekriterien zusätzlich vom Einsatz leberspezifischer Kontrastmittel, insbesondere in Kombination mit der Diffusionsbildgebung, wobei sowohl eine Erhöhung der Sensitivät als auch der diagnostischen Genauigkeit für Läsionen < 2cm nachgewiesen werden konnte. Bezüglich der Abgrenzung des HCC von anderen nodulären Herdläsionen der zirrhotischen Leber hat sich gezeigt, dass die gleichzeitig vorliegende arterielle Hypervaskularisation und Hypointensität in der hepatobiliären Phase als spezifisch für das Vorliegen eines HCC einzustufen ist. Zudem ist ein hypointenses Signal in der hepatobiliären Phase mit einem hohen Vorhersagewert von bis zu 100 % für das Vorliegen eines High-grade-dysplastischen Knotens oder HCC assoziiert. Bewertung: Die MRT unter Berücksichtigung von hepatobiliärer und diffusionsgewichteter Bildgebung ("diffusion-weighted imaging", DWI) stellt heutzutage die beste nichtinvasive Bilddiagnostik für die Detektion des HCC sowie zur Charakterisierung von Knoten in der zirrhotischen Leber dar, mit deutlichen Vorteilen gegenüber der CT bei der Detektion kleiner Läsionen < 2cm sowie der Dignitäts- und Prognoseeinschätzung hypovaskulärer Vorstufen im Rahmen der Hepatokarzinogenese. Empfehlung für die Praxis: Sowohl die MRT als auch die CT ermöglichen einen hohen Standard zur Diagnostik des HCC in der zirrhotischen Leber, mit Vorteilen der MRT bzgl. Detektionsrate und Spezifität. Die CT bietet für den klinischen Alltag eine schnelle, robuste sowie gut verfügbare Modalität mit Vorteilen bei Patienten in reduziertem Allgemeinzustand sowie eingeschränkter Compliance

Torsion pairs and rigid objects in tubes

We classify the torsion pairs in a tube category and show that they are in bijection with maximal rigid objects in the extension of the tube category containing the Pruefer and adic modules. We show that the annulus geometric model for the tube category can be extended to the larger category and interpret torsion pairs, maximal rigid objects and the bijection between them geometrically. We also give a similar geometric description in the case of the linear orientation of a Dynkin quiver of type A.Comment: 25 pages, 13 figures. Paper shortened. Minor errors correcte

Unenhanced helical computed tomography vs intravenous urography in patients with acute flank pain: accuracy and economic impact in a randomized prospective trial

Abstract.: Unenhanced helical computed tomography (UHCT) has evolved into a well-accepted alternative to intravenous urography (IVU) in patients with acute flank pain and suspected ureterolithiasis. The purpose of our randomized prospective study was to analyse the diagnostic accuracy of UHCT vs IVU in the normal clinical setting with special interest on economic impact, applied radiation dose and time savings in patient management. A total of 122 consecutive patients with acute flank pain suggestive of urolithiasis were randomized for UHCT (n=59) or IVU (n=63). Patient management (time, contrast media), costs and radiation dose were analysed. The films were independently interpreted by four radiologists, unaware of previous findings, clinical history and clinical outcome. Alternative diagnoses if present were assessed. Direct costs of UHCT and IVU are nearly identical (310/309 Euro). Indirect costs are much lower for UHCT because it saves examination time and when performed immediately initial abdominal plain film (KUB) and sonography are not necessary. Time delay between access to the emergency room and start of the imaging procedure was 32h 7min for UHCT and 36h 55min for IVU. The UHCT took an average in-room time of 23min vs 1h 21min for IVU. Mild to moderate adverse reactions for contrast material were seen in 3 (5%) patients. The UHCT was safe, as no contrast material was needed. The mean applied radiation dose was 3.3mSv for IVU and 6.5mSv for UHCT. Alternative diagnoses were identified in 4 (7%) UHCT patients and 3 (5%) IVU patients. Sensitivity and specificity of UHCT and IVU was 94.1 and 94.2%, and 85.2 and 90.4%, respectively. In patients with suspected renal colic KUB and US may be the least expensive and most easily accessable modalities; however, if needed and available, UHCT can be considered a better alternative than IVU because it has a higher diagnostic accuracy and a better economic impact since it is more effective, faster, less expensive and less risky than IVU. In addition, it also has the capability of detecting various additional renal and extrarenal pathologie

Degenerate flag varieties: moment graphs and Schr\"oder numbers

We study geometric and combinatorial properties of the degenerate flag varieties of type A. These varieties are acted upon by the automorphism group of a certain representation of a type A quiver, containing a maximal torus T. Using the group action, we describe the moment graphs, encoding the zero- and one-dimensional T-orbits. We also study the smooth and singular loci of the degenerate flag varieties. We show that the Euler characteristic of the smooth locus is equal to the large Schr\"oder number and the Poincar\'e polynomial is given by a natural statistics counting the number of diagonal steps in a Schr\"oder path. As an application we obtain a new combinatorial description of the large and small Schr\"oder numbers and their q-analogues.Comment: 25 page