The labial gene is required to terminate proliferation of identified neuroblasts in postembryonic development of the Drosophila brain

The developing brain of Drosophila has become a useful model for studying the molecular genetic mechanisms that give rise to the complex neuronal arrays that characterize higher brains in other animals including mammals. Brain development in Drosophila begins during embryogenesis and continues during a subsequent postembryonic phase. During embryogenesis, the Hox gene labial is expressed in the developing tritocerebrum, and labial loss-of-function has been shown to be associated with a loss of regional neuronal identity and severe patterning defects in this part of the brain. However nothing is known about the expression and function of labial, or any other Hox gene, during the postembryonic phase of brain development, when the majority of the neurons in the adult brain are generated. Here we report the first analysis of Hox gene action during postembryonic brain development in Drosophila. We show that labial is initially expressed in six larval brain neuroblasts, of which only four give rise to the labial expressing neuroblast lineages present in the late larval brain. Although MARCM-based clonal mutation of labial in these four neuroblast lineages does not result in an obvious phenotype, a striking and unexpected effect of clonal labial loss-of-function does occur during postembryonic brain development, namely the formation of two ectopic neuroblast lineages that are not present in wild-type brains. The same two ectopic neuroblast lineages are also observed following cell death blockage and, significantly, in this case the resulting ectopic lineages are Labial-positive. These findings imply that labial is required in two specific neuroblast lineages of the wildtype brain for the appropriate termination of proliferation through programmed cell death. Our analysis of labial function reveals a novel cell autonomous role of this Hox gene in shaping the lineage architecture of the brain during postembryonic development

On the Modeling of Correct Service Flows with BPEL4WS

Frameworks for composing Web Services offer a promising approach for realizing enterprise-wide and cross-organizational business applications. With BPEL4WS a powerful composition language exists. BPEL implementations allow orchestrating complex, stateful interactions among Web Services in a process-oriented way. One important task in this context is to ensure that respective flow specifications can be correctly processed, i.e., there will be no bad surprises (e.g., deadlocks, invocation of service operations with missing input data) at runtime. In this paper we subdivide BPEL schemes into different classes and discuss to which extent instances of these classes can be analyzed for the absence of control flow errors and inconsistencies. Altogether our work shall contribute to a more systematic evolution of the BPEL standard instead of overloading it with too many features

ADEPT2 - Next Generation Process Management Technology

If current process management systems shall be applied to a broad spectrum of applications, they will have to be significantly improved with respect to their technological capabilities. In particular, in dynamic environments it must be possible to quickly implement and deploy new processes, to enable ad-hoc modifications of single process instances at runtime (e.g., to add, delete or shift process steps), and to support process schema evolution with instance migration, i.e., to propagate process schema changes to already running instances. These requirements must be met without affecting process consistency and by preserving the robustness of the process management system. In this paper we describe how these challenges have been addressed and solved in the ADEPT2 Process Management System. Our overall vision is to provide a next generation process management technology which can be used in a variety of application domains

ADEPT - Next Generation Process Management Technology

In the ADEPT project we have been working on the design and implementation of a next generation process management technology for several years. Based on a conceptual framework for dynamic process changes, on innovative process support functions, and on advanced implementation concepts, the developed system enables the realization of adaptive, process-aware information systems (PAIS). Basically, process changes can take place at the process type as well as the process instance level: Changes of single process instances may have to be carried out in an ad-hoc manner (e.g., to deal with an exceptional situation) and must not affect system robustness and consistency. Process type changes, in turn, must be quickly accomplished in order to adapt the PAIS to business process changes. This may also include the migration of (thousands of) instances to the new process schema (if desired). Important requirements are to perform respective migrations on-the-fly, to preserve correctness, and to avoid performance penalties

X-Ray Scattering at FeCo(001) Surfaces and the Crossover between Ordinary and Normal Transitions

In a recent experiment by Krimmel et al. [PRL 78, 3880 (1997)], the critical behavior of FeCo near a (001) surface was studied by x-ray scattering. Here the experimental data are reanalyzed, taking into account recent theoretical results on order-parameter profiles in the crossover regime between ordinary and normal transitions. Excellent agreement between theoretical expectations and the experimental results is found.Comment: 9 pages, Latex, 1 PostScript figure, to be published in Phys.Rev.

New Microscopic Connections of Thermodynamics

This is a work that discusses the foundations of statistical mechanics (SM) by revisiting its postulates in the case of the two main extant versions of the theory. A third one will here we added, motivated by the desire for an axiomatics that possesses some thermodynamic “flavor”, which does not happen with neither of the two main SM current formulations, namely, those of Gibbs’ (1; 2), based on the ensemble notion, and of Jaynes’, centered on MaxEnt (3; 4; 5). One has to mention at the outset that we “rationally understand” some physical problem when we are able to place it within the scope and context of a specific “Theory”. In turn, we have a theory when we can both derive all the known interesting results and successfully predict new ones starting from a small set of axioms. Paradigmatic examples are von Neumann’s axioms for Quantum Mechanics, Maxwell’s equations for electromagnetism, Euclid’s axioms for classical geometry, etc. (1; 3). Boltzmann’s main goal in inventing statistical mechanics during the second half of the XIX century was to explain thermodynamics. However, he did not reach the axiomatic stage described above. The first successful SM theory was that of Gibbs (1902) (2), formulated on the basis of four ensemble-related postulates (1). The other great SM theory is that of Jaynes’ (4), based upon the MaxEnt axiom (derived from Information Theory): ignorance is to be extremized (with suitable constraints). Thermodynamics (TMD) itself has also been axiomatized, of course, using four macroscopic postulates (6). Now, the axioms of SM and of thermodynamics belong to different worlds altogether. The former speak of either “ensembles” (Gibbs), which are mental constructs, or of “observers’ ignorance” (Jaynes), concepts germane to thermodynamics’ language, that refers to laboratory-parlance. In point of fact, TMD enjoys a very particular status in the whole of science, as the one and only theory whose axioms are empirical statements (1). Of course, there is nothing to object to the two standard SM-axiomatics referred to above. However, a natural question emerges: would it be possible to have a statistical mechanics derived from axioms that speak, as far as possible, the same language as that of thermodynamics? To what an extent is this feasible? It is our intention here that of attempting a serious discussion of such an issue and try to provide answers to the query, following ideas developed in (7; 8; 9; 10; 11; 12; 13).This work is founded by the Spain Ministry of Science and Innovation (Project FIS2008-00781) and by FEDER funds (EU).Peer reviewe

Coulomb blockade effects in driven electron transport

We study numerically the influence of strong Coulomb repulsion on the current through molecular wires that are driven by external electromagnetic fields. The molecule is described by a tight-binding model whose first and last site is coupled to a respective lead. The leads are eliminated within a perturbation theory yielding a master equation for the wire. The decomposition into a Floquet basis enables an efficient treatment of the driving field. For the electronic excitations in bridged molecular wires, we find that strong Coulomb repulsion significantly sharpens resonance peaks which broaden again with increasing temperature. By contrast, Coulomb blockade has only a small influence on effects like non-adiabatic electron pumping and coherent current suppression.Comment: 9 pages, 7 figures. Added a plot for temperature dependence of resonance peaks. Published versio