Standard isotrivial fibrations with p_g=q=1

A smooth, projective surface $S$ of general type is said to be a \emph{standard isotrivial fibration} if there exist a finite group $G$ which acts faithfully on two smooth projective curves $C$ and $F$ so that $S$ is isomorphic to the minimal desingularization of $T:=(C \times F)/G$. If $T$ is smooth then $S=T$ is called a \emph{quasi-bundle}. In this paper we classify the standard isotrivial fibrations with $p_g=q=1$ which are not quasi-bundles, assuming that all the singularities of $T$ are rational double points. As a by-product, we provide several new examples of minimal surfaces of general type with $p_g=q=1$ and $K_S^2=4,6$.Comment: 31 pages. Final version, to appear in J. Algebr

Homotopy theory of Hopf Galois extensions

We introduce the concept of homotopy equivalence for Hopf Galois extensions and make a systematic study of it. As an application we determine all H-Galois extensions up to homotopy equivalence in the case when H is a Drinfeld-Jimbo quantum group.Comment: 28 page

On Galois coverings and tilting modules

Let A be a basic connected finite dimensional algebra over an algebraically closed field, let G be a group, let T be a basic tilting A-module and let B the endomorphism algebra of T. Under a hypothesis on T, we establish a correspondence between the Galois coverings with group G of A and the Galois coverings with group G of B. The hypothesis on T is expressed using the Hasse diagram of basic tilting A-modules and is always verified if A is of finite representation type. Then, we use the above correspondence to prove that A is simply connected if and only if B is simply connected, under the same hypothesis on T. Finally, we prove that if a tilted algebra B of type Q is simply connected, then Q is a tree and the first Hochschild cohomology group of B vanishesComment: Fourth version. A result on the simple connectedness of tilted algebras was adde

Ties of resistance and cooperation: Aedemon, Lusius Quietus and the Baquates

Gaius' decision to dissolve the protectorate of Mauretania and to depose its client king, Ptolemaeus, led to the outbreak of the Revolt of Aedemon (AD 40). This paper will develop a number of innovative thoughts and hypotheses concerning the extent of this rebellion and its possible impact on the deposition of Ptolemaeus, as well as the role of the Romans in its suppression. The main aim is to explore the connection between this revolt, Trajanus' famous general Lusius Quietus (cos. AD 117?), and the Baquates, an indigenous Mauretanian tribe. I will suggest that Lusius Quietus was descended from a chief of a (semi-)nomadic tribe who supported the Roman cause during the Revolt of Aedemon. Considering the setting and dimension of this revolt, as well as the unrest in Mauretania at the time of Lusius Quietus' execution by Hadrianus, I argue that this tribe can be identified as the Baquates. This reconstruction suggests a long-lasting and particularly positive relationship between this tribe and Rome. It allows for a further reconsideration of the relationship between (semi-)nomadic and Roman/sedentary groups in Roman North Africa, to the detriment of one-sided analytical schemes that stress endemic hostility

MARINE RESERVES WITH ENDOGENOUS PORTS: EMPIRICAL BIOECONOMICS OF THE CALIFORNIA SEA URCHIN FISHERY

Marine reserves are gaining substantial public support as tools for commercial fisheries management Harvest sector responses will influence policy performance, yet biological studies often depict harvester behavior as spread uniformly over fishing grounds and unresponsive to economic opportunities. Previous bioeconomic analyses show that these behavioral assumptions are inconsistent with empirical data and, more importantly, lead to overly optimistic predictions about harvest gains from reserves. This paper adds another layer of behavioral realism to the bioeconomics of marine reserves by endogenizing fisher home port choices with a partial adjustment share model. Estimated with Seemingly Unrelated Regression over monthly data, this approach allows simulation of both short- and long-run behavioral response to changes induced by marine reserve formation. The findings cast further doubt on the notion that marine reserves generate long-run harvest benefits.Resource /Energy Economics and Policy,

Lectin ligands: New insights into their conformations and their dynamic behavior and the discovery of conformer selection by lectins

The mysteries of the functions of complex glycoconjugates have enthralled scientists over decades. Theoretical considerations have ascribed an enormous capacity to store information to oligosaccharides, In the interplay with lectins sugar-code words of complex carbohydrate structures can be deciphered. To capitalize on knowledge about this type of molecular recognition for rational marker/drug design, the intimate details of the recognition process must be delineated, To this aim the required approach is garnered from several fields, profiting from advances primarily in X-ray crystallography, nuclear magnetic resonance spectroscopy and computational calculations encompassing molecular mechanics, molecular dynamics and homology modeling. Collectively considered, the results force us to jettison the preconception of a rigid ligand structure. On the contrary, a carbohydrate ligand may move rather freely between two or even more low-energy positions, affording the basis for conformer selection by a lectin. By an exemplary illustration of the interdisciplinary approach including up-to-date refinements in carbohydrate modeling it is underscored why this combination is considered to show promise of fostering innovative strategies in rational marker/drug design

II-muskolu kollu demm ta' 'II-jien u lilhinn minnu'

Dan I-artiklu jaghti harsa Iejn l-istorja tad-dikotomija bejn il-qalb u I-mohh, dikotomija Ii tikkaratterizza l-poema 'II-Jien u Lilhinn Minnu' ta' Dun Karm Psaila. Din il-harsa storika turi lj I-ghazliet li ghamel Dun Karm jirriflettu qaghdiet politici Ii l-gheruq taghhom imorru lura sekli shah.peer-reviewe