Absolute beam position monitoring using HOM-damper signals

To preserve the required beam quality in an e+/e- collider it is necessary to have a very precise beam position control at each accelerating cavity. An elegant method to avoid additional length and beam disturbance is the usage of signals from existing HOM-dampers. The magnitude of the displacement is derived from the amplitude of a dipole mode whereas the sign follows from the phase comparison of a dipole and a monopole HOM. To check the performance of the system, a measurement setup has been built with an antenna which can be moved with micrometer resolution to simulate the beam. Furthermore we have developed a signal processing to determine the absolute beam displacement. Measurements on the HOM-damper cell can be done in the frequency domain using a network analyser. Final measurements with the nonlinear time dependent signal processing circuit has to be done with very short electric pulses simulating electron bunches. Thus, we have designed a sub nanosecond pulse generator using a clipping line and the step recovery effect of a diode. The measurement can be done with a resolution of about 10 micrometers. Measurements and numerical calculations concerning the monitor design and the pulse generator are presented

Intelligent doctor patient matching: how José Mello saude experiments towards data-driven and patient-centric decision making

While data-driven decision-making is generally accepted as a fundamental capability of a competitive firm, many firms are facing difficulties in developing this capability. This case demonstrates how a private healthcare organization, José de Mello Saúde, engages in collaboration with a global university-led program for such capability building, in a pilot project of intelligent doctor-patient matching. The case walks the reader through the entire data science pipeline, from project scoping to data curation, modelling, prototype testing, until implementation. It enables discussions on how to overcome managerial challenges and build the needed capabilities to successfully integrate advanced analytics into the organization’s operations

Analysis of HOM interaction between cavities by multi-modal s-parameter measurements

Accelerating cavities exchange HOM power through interconnecting beam pipes in case of signal frequencies above the cut-off of their propagating waveguide modes. This may lead either to improved HOM damping or - in the case most severe - to unwanted phase coherence of fields to the beam. Therefore the knowledge of the scattering properties of a cavity as a line element is needed to analyse all kinds of RF cavity-cavity interaction. Since there is a lack of measurement tools capable to provide a multidimensional scattering matrix at a given frequency point, we have been developing a method for this purpose. It uses a set of 2-port S-parameters of the device under test, embedded in a number of geometrically different RF environments. The application of the method is demonstrated with copper models of TESLA cavities

LISP-SP : A Portable INTERLISP Subset Interpreter for Mini-Computers

This paper describes the implementation of LISP-SP, a decendant of LISPF3, an INTERLISP compatible LISP system originating from DATALOGILABORIET, Uppsala, Sweden 1978. Two data types have been added to LISPF3, namely floating point numbers and. arrays, and a swapping algorithm as been implemented for data arrays. Besides those new data types, a different method of storing lists internally has been adopted which is based on the idea that in LISPF3 each list cell consists of two memory cells, one for CAR and one for CDR, where in most cases, CDR contains only a pointer to the successor list element, and list space can be saved when keeping list elements 'physically' adjacent as much as possible. The CDR pointer is then available implicitly by incrementing the address to the internal structure carrying lists, except when the sequence of elements is broken through application of LISP functions. In those cases, special pointers are used which do not represent CDR values, but are only inspected to determine the location of the next element. This method was selected to avoid program addressing Space problems on mini-computers, resulting from the expansion of LISPF3's internal data structures from 16-bit to 32-bit width, as required by LISPF3 users asking for 'more user address space’. These enhancements of LISPF3 lead to a complete redesign of the system, where special attention was put on producing readable and self-documenting software. The resulting system differs enough from its predecessor to justify a different name, therefore, the name LISP-SP was selected, reflecting the fact that sublist structures are marked internally by (S)tored (P)arentheses. When handling lists in this way, examples show that the number of memory cells allocated for a given package of LISP functions is approximately the same as in LISPF3. If, however, LISPF3's data structures had been widened to 32-bit elements, then twice the amourt of program addressing space for lists would be neccessary to store the same package - too much for most of the mini-computers currently available. The system is available at a nominal charge from Prof. Dr. P. Raulefs Universität Kaiserslautern Fachbereich Informatik Postfach 3049 D-6750 Kaiserslautern West German

Effiziente und neuartige Verfahren zur Optimierung von Kraftfeldparametern bei atomistischen Molekularen Simulationen kondensierter Materie

Molekulare Simulationen ermöglichen es, den Einfluss mikroskopischer Prozesse auf makroskopische Phänomene zu studieren. Um Simulationen in den Naturwissenschaften erfolgreich anwenden zu können, müssen geeignete molekulare Modelle vorliegen. Das Fundament einer Simulation zur quantitativen Vorhersage von physikalischen Eigenschaften ist das sogenannte Kraftfeld. Die Hauptschwierigkeit liegt in dessen Parametrisierung. Dies manuell durchzuführen, ist sehr zeitaufwendig, da für jeden Parametersatz eine aufwendige Simulation durchzuführen ist. In dieser Arbeit wird ein neues automatisiertes Parametrisierungsschema vorgeschlagen, welches auf der Lösung eines mathematischen Optimierungsproblems basiert. Innerhalb des Optimierungsprozesses werden Eigenschaften, die aus einer Molekularen Simulation resultieren, an ihre entsprechenden experimentellen Referenzdaten angepasst. Da Molekulare Simulationen eine hohe Komplexität aufweisen und die resultierenden Eigenschaften mit statistischen Rauschen behaftet sind, wird das Optimierungsproblem sowohl mit bereits vorhandenen als auch mit neuartigen, effizienten und robusten numerischen Algorithmen gelöst

Transversal loss factor of an rf-focussing iris structure with rectangular holes

By replacing the irises in an electron linac by a slit one gets a structure capable of focussing/defocussing an electron beam (rf-quadrupoles). Therefore one can think of a combination of rf- and conventional magnetic quadrupoles for transversal focussing in linear-colliders. Furthermore they can meet the demands of BNS-damping without initial energy spread. Considering multibunch-operation of a collider, the long-range wake behaviour of this kind of structure has to be investigated. A three-cell structure has been built and investigated for dipole-type transversal long-range wakes. The experimental results are compared to numerical simulations done with MAFIA

The influence of wakefields on superconducting TESLA-cavities in FEL-operation

Due to the additional need of very short bunches for the FEL operation with the TESLA-machine strong wakefield effects are expected. One third of the total wakefield energy per bunch is radiated into the frequency region above the energy gap of Cooper pairs in superconducting niobium. The energy of the cooper pairs in superconducting niobium at 2 K corresponds to a frequency of 700 GHz. An analytical and experimental estimation for the overall energy loss of the FEL bunch above energy gap is presented. The analytical method is based on a study from R. B. Palmer [1]. The results of the wakefield estimations are used to calculate possible quality factor reduction of the TESLA cavities during FEL operation. Results are presented

Vulnerability of vascular endothelium in lipopolysaccharide toxicity: effect of (acyl) carnitine on endothelial stability

The literature presented illustrates that lipopolysaccharide (LPS), from bacterial cell walls, induces tumour necrosis factor (TNF) synthesis in macrophages. TNF affects a number of cell types, amongst which are endothelial cells, within a few hours. Its injection has been shown to produce all symptoms of the toxic syndrome. In the present communication the vulnerability of endothelial cells will be stressed. These cells require carnitine not only for fatty acid oxidation but also for membrane protection and repair. As endothelial cells lose carnitine during hypoperfusion, it is speculated that the supply of carnitine during the early phase of LPS toxicity in rats might delay or avoid loss of endothelial functions. Earlier it was observed that hearts from rats, injected 3 h previously with LPS, showed strongly increased interstitial fluid production compared to hearts from control rats, even when TNF was present during a 3 h in vitro perfusion. It showed that LPS in vivo generates factors other than TNF, such as platelet activating factor (PAF), that are responsible for the increased capillary permeability