A local global principle for regular operators in Hilbert C*-modules

Hilbert C*-modules are the analogues of Hilbert spaces where a C*-algebra plays the role of the scalar field. With the advent of Kasparov's celebrated KK-theory they became a standard tool in the theory of operator algebras. While the elementary properties of Hilbert C*-modules can be derived basically in parallel to Hilbert space theory the lack of an analogue of the Projection Theorem soon leads to serious obstructions and difficulties. In particular the theory of unbounded operators is notoriously more complicated due to the additional axiom of regularity which is not easy to check. In this paper we present a new criterion for regularity in terms of the Hilbert space localizations of an unbounded operator. We discuss several examples which show that the criterion can easily be checked and that it leads to nontrivial regularity results.Comment: 31 pages, 2 figures; v3: revised version containing an erratum to v2 clarifying the contributions by Fran\c{c}ois Pierro

PMAS: The Potsdam Multi Aperture Spectrophotometer. II. The Wide Integral Field Unit PPak

PPak is a new fiber-based Integral Field Unit (IFU), developed at the Astrophysical Institute Potsdam, implemented as a module into the existing PMAS spectrograph. The purpose of PPak is to provide both an extended field-of-view with a large light collecting power for each spatial element, as well as an adequate spectral resolution. The PPak system consists of a fiber bundle with 331 object, 36 sky and 15 calibration fibers. The object and sky fibers collect the light from the focal plane behind a focal reducer lens. The object fibers of PPak, each 2.7 arcseconds in diameter, provide a contiguous hexagonal field-of-view of 74 times 64 arcseconds on the sky, with a filling factor of 60%. The operational wavelength range is from 400 to 900nm. The PPak-IFU, together with the PMAS spectrograph, are intended for the study of extended, low surface brightness objects, offering an optimization of total light-collecting power and spectral resolution. This paper describes the instrument design, the assembly, integration and tests, the commissioning and operational procedures, and presents the measured performance at the telescope.Comment: 14 pages, 21 figures, accepted at PAS

The STELLA Robotic Observatory on Tenerife

The Astrophysical Institute Potsdam (AIP) and the Instituto de Astrofísica de Canarias (IAC) inaugurated the robotic telescopes STELLA-I and STELLA-II (STELLar Activity) on Tenerife on May 18, 2006. The observatory is located on the Izaña ridge at an elevation of 2400 m near the German Vacuum Tower Telescope. STELLA consists of two 1.2 m alt-az telescopes. One telescope fiber feeds a bench-mounted high-resolution echelle spectrograph while the other telescope feeds a wide-field imaging photometer. Both scopes work autonomously by means of artificial intelligence. Not only that the telescopes are automated, but the entire observatory operates like a robot, and does not require any human presence on site

On the test-driven development and validation of business rules

Abstract: In recent years we have seen the rise of a new type of software called business rule management systems (BRMS). These are systems to externalize business rules and to provide a facility for centralized business rule management. This addresses an urgent need businesses do have nowadays: to change their business rules in order to adapt to a rapidly business environment, and to overcome the restricting nature of slow IT change cycles. Early manifestations of business rule engines which have their roots in the realm of artificial intelligence and inference systems were complex, expensive to run and maintain and not very business-user friendly. Improved technology providing enhanced usability, scalability and performance, as well as less costly maintenance and better understanding of the underlying inference systems makes the current generation of business rule engines (BRE) and rules technology more usable. However, there are a number of risks and difficulties that have to be taken into account when employing a BRMS. Another recent trend that tries to address the same problem of slow IT change cycles is agile software engineering, in particular test driven development. In this paper, we investigate how BRMSs can be used in conjunction with test driven development. The result is an approach that facilitates the authoring of business rules significantly and safeguards it by providing means for automated validation and verification

Case Studies on the Thermally Induced Stresses in Insulating Glass Units via Numerical Calculation

In the structural design of facade glazing, various types of loads such as dead weight, wind and climatic loads (pressure differences) must be taken into account. In practice, however, there are many cases of damage that can be attributed to direct solar radiation. In these cases, a so-called thermally induced fracture takes place, which can occur as a result of large in-plane temperature differences within the glass. Due to the increasing complexity of glazing constructions, this load type should be taken into account in future glass design. For this reason, thermal-mechanical investigations, were conducted. Commercially used double and triple insulating glass units were considered as vertical glazing and the solar direct absorptance per glass pane was varied. For numerical calculations, measured temperature data from the German Weather Service and free available Clear Sky model data were used as meteorological input. The results show that solar irradiance, along with temperature, is the driving influence on the thermally induced stress in insulating glass units. The investigations indicate that the inner pane becomes relevant on colder days and the outer pane on warmer days. Results also show, that the level of the outside temperature plays a negligible role for the thermally induced stresses of the middle pane

ContractLog: An Approach to Rule Based Monitoring and Execution of Service Level Agreements. in RuleML 2005

Abstract. In this paper we evolve a rule based approach to SLA representation and management which allows separating the contractual business logic from the application logic and enables automated execution and monitoring of SLA specifications. We make use of a set of knowledge representation (KR) concepts and combine adequate logical formalisms in one expressive formal framework called ContractLog.

A logic based sla management framework

Abstract. Management, execution and maintenance of Service Level Agreements (SLAs) in the upcoming service oriented IT landscape need new levels of flexibility and automation not available with the current technology. In this paper we evolve a rule based approach to SLA representation and management which allows a clean separation of concerns, i.e. the contractual business logic are separated from the application logic. We make use of sophisticated, logic based knowledge representation (KR) concepts and combine adequate logical formalisms in one expressive logic based framework called ContractLog. ContractLog underpins a declarative rule based SLA (RBSLA) language with which to describe SLAs in a generic way as machine readable and executable contract specifications. Based on ContractLog and the RBSLA we have implemented a high level architecture for the automation of electronic contracts- a rule-based Service Level Management tool (RBSLM) capable of maintaining, monitoring and managing large amounts of complex contract rules. 1 Why declarative rule-based SLA representation? Our studies of a vast number of SLAs currently used throughout the industry have revealed that today’s prevailing contracts are plain natural language documents. Consequently

Rearrangement of the extracellular domain/extracellular loop 1 interface is critical for thyrotropin receptor activation

The thyroid stimulating hormone receptor (TSHR) is a G protein-coupled receptor (GPCR) with a characteristic large extracellular domain (ECD). TSHR activation is initiated by binding of the hormone ligand TSH to the ECD. How the extracellular binding event triggers the conformational changes in the transmembrane domain (TMD) necessary for intracellular G protein activation is poorly understood. To gain insight in this process, the knowledge on the relative positioning of ECD and TMD and the conformation of the linker region at the interface of ECD and TMD are of particular importance. To generate a structural model for the TSHR we applied an integrated structural biology approach combining computational techniques with experimental data. Chemical cross-linking followed by mass spectrometry yielded 17 unique distance restraints within the ECD of the TSHR, its ligand TSH, and the hormone-receptor complex. These structural restraints generally confirm the expected binding mode of TSH to the ECD as well as the general fold of the domains and were used to guide homology modeling of the ECD. Functional characterization of TSHR mutants confirms the previously suggested close proximity of Ser-281 and Ile-486 within the TSHR. Rigidifying this contact permanently with a disulfide bridge disrupts ligand-induced receptor activation and indicates that rearrangement of the ECD/extracellular loop 1 (ECL1) interface is a critical step in receptor activation. The experimentally verified contact of Ser-281 (ECD) and Ile-486 (TMD) was subsequently utilized in docking homology models of the ECD and the TMD to create a full-length model of a glycoprotein hormone receptor

PMAS: The Potsdam Multi-Aperture Spectrophotometer. I. Design, Manufacture, and Performance

We describe the design, manufacture, commissioning, and performance of PMAS, the Potsdam Multi-Aperture Spectrophotometer. PMAS is a dedicated integral field spectrophotometer, optimized to cover the optical wavelength regime of 0.35--1um. It is based on the lens array -- fiber bundle principle of operation. The instrument employs an all-refractive fiber spectrograph, built with CaF2 optics, to provide good transmission and high image quality over the entire nominal wavelength range. A set of user-selectable reflective gratings provides low to medium spectral resolution in first order of approx. 1.5, 3.2, and 7 A, depending on the groove density (1200, 600, 300 gr/mm). While the standard integral field unit (IFU) uses a 16x16 element lens array, which provides seeing-limited sampling in a relatively small field-of-view (FOV) in one of three magnifications (8x8, 12x12, or 16x16 arcsec^2, respectively), a recently retrofitted bare fiber bundle IFU (PPak) expands the FOV to a hexagonal area with a footprint of 65x74 arcsec^2. Other special features include a cryogenic CCD camera for field acquisition and guiding, a nod-shuffle mode for beam switching and improved sky background subtraction, and a scanning Fabry-Perot etalon in combination with the standard IFU (PYTHEAS mode). PMAS was initially designed and built as an experimental traveling instrument with optical interfaces to various telescopes (Calar Alto 3.5m, ESO-VLT, LBT). It is offered as a common user instrument at Calar Alto under contract with MPIA Heidelberg since 2002.Comment: accepted for publication in PASP, 18 pages, 21 figure