Showing papers by "Wolfgang Wagner published in 2000"

The IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam

Abstract: In the 1960’s an industrial formulation for the thermodynamic properties of water and steam was developed called “The 1967 IFC Formulation for Industrial Use” (IFC-67) [1]. Since 1967 IFC-67 has been formally recognized to calculate thermodynamic properties of water and steam for any official use such as performance guarantee calculations of power cycles. In addition to this, IFC-67 has been used for innumerable other industrial applications. However, during the last few years a number of weaknesses of IFC-67 have appeared. This fact and the progress that has been achieved in mathematical methods to develop accurate equations of state led to the development of a new industrial formulation in an international research project initiated and coordinated by the International Association for the Properties of Water and Steam (IAPWS).

A Reference Equation of State for the Thermodynamic Properties of Nitrogen for Temperatures from 63.151 to 1000 K and Pressures to 2200 MPa

Abstract: A new formulation for the thermodynamic properties of nitrogen has been developed. Many new data sets have become available, including high accuracy data from single and dual-sinker apparatuses which improve the accuracy of the representation of the pρT surface of gaseous, liquid, and supercritical nitrogen, including the saturation states. New measurements of the speed of sound from spherical resonators yield accurate information on caloric properties in gaseous and supercritical nitrogen. Isochoric heat capacity and enthalpy data have also been published. Sophisticated procedures for the optimization of the mathematical structure of equations of state and special functional forms for an improved representation of data in the critical region were used. Constraints regarding the structure of the equation ensure reasonable results up to extreme conditions of temperature and pressure. For calibration applications, the new reference equation is supplemented by a simple but also accurate formulation, valid only for supercritical nitrogen between 250 and 350 K at pressures up to 30 MPa. The uncertainty in density of the new reference equation of state ranges from 0.02% at pressures less than 30 MPa up to 0.6% at very high pressures, except in the range from 270 to 350 K at pressures less than 12 MPa where the uncertainty in density is 0.01%. The equation is valid from the triple point temperature to temperatures of 1000 K and up to pressures of 2200 MPa. From 1000 to 1800 K, the equation was validated with data of limited accuracy. The extrapolation behavior beyond 1800 K is reasonable up to the limits of chemical stability of nitrogen, as indicated by comparison to experimental shock tube data.

Biotechnology and the European public

Abstract: The latest European sample survey of public perceptions of biotechnology reveals widespread opposition to genetically modified (GM) food in much of Europe, but public attitudes to medical and environmental applications remain positive.

Time step truncation error in direct simulation Monte Carlo

Abstract: The time step truncation error in direct simulation Monte Carlo calculations is found to be O(Δt2) for a variety of simple flows, both transient and steady state. The measured errors in the transport coefficients (viscosity, thermal conductivity, and self-diffusion) are in good agreement with predictions from Green-Kubo analysis [N. Hadjiconstantinou, Phys. Fluids 12, 2634 (2000)].

Large-scale soil moisture mapping in western Africa using the ERS scatterometer

Abstract: Water is a critical resource in western Africa, and droughts are a serious threat to the population and the environment. A technique to retrieve soil moisture from ERS scatterometer data is applied over a large region covering southern Mali and Burkina Faso. How the method accounts for the wide range of climatic and physiographic conditions encountered in the study area is discussed. An analysis of monthly soil moisture maps covering six years of data shows that the climatic conditions are well reflected in the remotely sensed data.

‘I have some faith and at the same time I don't believe’ — cognitive polyphasia and cultural change in India

Abstract: Issues of community and health are tightly linked to local cultures and to the system of traditional representations about health and illness. These systems, however, are rarely static, but are in constant flux through economic and technological developments — what is often called ‘modernisation’ — that entail new representations becoming part of everyday thinking. In this process the novel often plays the role of an icon of modernity in situations that evoke the idea of progress, while the traditional prevails in more static social structures such as the family. This co-existence of rarely compatible representations is called cognitive polyphasia. The present interview-study investigates the way 39 residents of the North-Indian city of Patna cope with contradictions implied by traditional and Western psychiatric notions of mental illness, their aetiology and treatment. It is shown that each of the two ways of thinking is situated and used in specific social settings. Some implications of cognitive polyphasia for community development are discussed. Copyright © 2000 John Wiley & Sons, Ltd.

An Efficient Stochastic Algorithm for Studying Coagulation Dynamics and Gelation Phenomena

Abstract: A new class of efficient stochastic algorithms for the numerical treatment of coagulation processes is proposed. The algorithms are based on the introduction of fictitious jumps combined with an acceptance-rejection technique for distributions depending on particle size. The increased efficiency is demonstrated by numerical experiments. In particular, gelation phenomena are studied.

Results of prophylactic irradiation in patients with resected keloids--a retrospective analysis.

Abstract: The data of 139 patients with 166 keloids treated postoperatively between 1962 and 1996 were evaluated for prognostic factors and outcomes. Treatment commenced within 48 h after surgery. Radiotherapy was carried out as brachytherapy, using an integrated radionuclide 90 Sr-90Y surface applicator. The median dose delivered to the subcutis amounted to 14 Gy (range 7.5-28.5 Gy). The overall recurrence-free response rate was calculated to be 80% for all keloids. Response rates differed significantly (p < 0.001) between the different anatomical regions. The recurrence rate was lowest (2%) with keloids of the face and neck and highest with keloids of the thorax (49%). Outcome also differed significantly, depending on the etiology. Keloids following burns had a poorer success rate than those developing after surgery or mechanical trauma (p < 0.001). We were unable to demonstrate any significance in outcome related to gender, age or size. No direct correlation was found between total doses and response rates. In our patients there were no signs of secondary malignancies in the irradiation area within a median follow-up period of 12 years. Two new prognostic factors have been identified: keloid etiology and localization of the disorder.

Approximative solution of the coagulation-fragmentation equation by stochastic particle systems

Abstract: This paper studies stochastic particle systems related to the coagulation fragmentation equation. For a certain class of unbounded coagulation kernels and fragmentation rates, relative compactness of the stochastic systems is established and weak accumulation points are characterized as solutions. These results imply a new existence theorem. Finally a simulation algorithm based on the particle systems is proposed

Cranial neuronavigation in neurosurgery: assessment of usefulness in relation to type and site of pathology in 284 patients.

Abstract: Objective: Neuronavigation improves intraoperative topographical orientation in neurosurgery. We wanted to better define the practical value of this technique in relation to the pathology operated on and the types of cranial surgery that profit the most from it. Methods: Usefulness, interactive use and probably preventive effect of neuronavigation in cranial neurosurgery were assessed in a consecutive series of 284 patients on the basis of questionnaires with two- or five-point scale ratings by different neurosurgeons. Results: Neuronavigation was most helpful in tumors of the hemispheres (particularly the central area) not visible at the cortical surface or resembling normal white matter, and in endoscopic procedures within small ventricles or cysts with non-translucent walls or when vision was blurred by cloudy CSF. In the same pathologies and surgical procedures, the device was interactively used, taking advantage of the specific possibilities of interactive image-guided neurosurgery. A probably preventive effect of neuronavigation was noted in operations in eloquent areas; highest scores were given for intraaxial tumors of the central region. The subjective assessments of usefulness, interactive use or preventive effect were not dependent on the involvement of the neurosurgeons in this study. Conclusion: We recommend this technique in resecting tumors in eloquent areas of the cortex or white matter, in approaching deep-seated processes not visible at the cortical surface, in defining borders of tumors resembling normal brain tissue, and in guiding endoscopes where ventricles are small or vision is blurred. This recommendation applies to any neurosurgeon familiar with the technique and managing neurosurgical cases requiring precise topographical orientation where normal anatomic landmarks are missing.

Prognostic value of hemoglobin concentrations in patients with advanced head and neck cancer treated with combined radio-chemotherapy and surgery.

Abstract: Hemoglobin levels are currently the focus of interest as prognostic factors in patients with head and neck cancer. Most published clinical trials have confirmed hemoglobin to possess a significant influence on survival in patients treated with radiotherapy. In our study we have investigated the prognostic value of hemoglobin in a combined modality schedule.

Monitoring Moderate Slope Movements (Landslides) in the Southern French Alps Using Differential SAR Interferometry

Abstract: In this paper differential SAR-Interferometry (DInSAR) is applied to study a landslide close to La Valette which is situated in the southern French Alps. The general capability of D-InSAR to determine the field of movement of a moderately moving landslide is shown, by carrying out the phase unwrapping and projecting the measured displacement to the direction of the movement. The data analysed in this study comprise three ERS-1/2-Tandem pairs from 1995/96 which allow to measure movements that took place in the time span of 24 hours. Field measurements were available to assess the accuracy of the interferometrically extracted displacement values. Despite of the different acquisition intervals of the satellite and the ground measurements an agreement in the order of 1.2 cm/day could be assigned.

Diagnostic radiation oncology: malignant cystosarcoma phylloides.

Abstract: Cystosarcoma phylloides is a rare, mostly benign tumor of the breast. In most cases curative treatment is possible with complete surgical excision of the lesions. However, there is a high local recurrence rate up to 46%. There are only few reported successful treatments radiotherapy in cystoarcoma phylloides. Radiotherapy is indicated in patients with locoregional recurrent disease and those with symptomatic metastases. Patient: We present a case of a 54-year-old women with a painless mass in the right breast. Clinical examination showed a large, firm tumor and axillary lymph node metastases. The patient underwent mastectomy and axillary lymph node dissection. Histopathology showed a cystosarcoma phylloides measuring 30 × 25 × 19 cm as well as lymph nodes metastases measuring 9.5 cm. Despite a R0 resection the patient developed 4 thoracic wall recurrences within 2 years. At 18 months there were additional multiple pulmonary and pleural lesions with a maximum diameter of 6.5 cm. Subsequently the patient received polychemotherapy. There was a significant response of the thoracic wall disease as well as of the pulmonary and pleural lesions. Six months later there was further progress of the thoracic wall disease and the pulmonary lesions. Following this the patient underwent radiation therapy of her right thoracic wall with 50 Gy which lead clinically to a quick response. For the past 5 months there has been no evidence of thoracic wall disease recurrence. Conclusion: This is an unusual case of cystosarcoma phylloides and response to different therapeutic modalities. Cystosarcoma phylloides showed to be a radiosensitive tumor. Thus postoperative radiation therapy is indicated to prevent local recurrences.

The limiting kinetic equation of the Consistent Boltzmann Algorithm for dense gases

Abstract: This paper establishes a theoretical foundation for the Consistent Boltzmann Algorithm (CBA) by deriving the limiting kinetic equation. The formulation is similar to the proof by one of the authors that the Boltzmann equation is the limiting kinetic equation for Direct Simulation Monte Carlo [W. Wagner, J. Statist. Phys. 66:1011 (1992)]. For a simplified model distilled from CBA, the limiting equation is solved numerically, and very good agreement with the predictions of the theory is found.

Double-sided microstrip detectors for the high radiation environment in the HERA-B experiment

Abstract: The design of the double-sided microstrip detectors for the HERA-B experiment at DESY is discussed, in particular with respect to the strong requirements imposed by the high radiation environment and by the challenging mechanical construction. The detectors are tested with an infrared laser setup and first results from operation in the experiment in 1997 are presented.

Search for new physics in photon-lepton events in pp̄ collisions at √s = 1.8 TeV

Abstract: We present the results of a search in p (p) over bar collisions at roots=1.8 TeV for anomalous production of events containing a photon and a lepton (e or mu ), both with large transverse energy, using 86 pb (-1) of data collected with the Collider Detector at Fermilab during the 1994-1995 collider run at the Fermilab Tevatron. The presence of large missing transverse energy (is not an element of(T)), additional photons, or additional leptons in these events is also analyzed. The results are consistent with standard model expectations, with the possible exception of photon-lepton events with large is not an element of(T), for which the observed total is 16 events and the expected mean total is 7.6+/-0.7 events.

Migration in Großstädten - Folgen der europäischen Osterweiterung für mitteleuropäische Stadtstrukturen -

Abstract: In der Literatur zur Migration wird haufig die Bedeutung von Migrationsnetzwerken hervorgehoben. Diese erleichtern den Migranten nicht nur die Wanderung selbst, sondern beeinflussen auch ihre Ansiedlung im Aufnahmegebiet. In diesem Beitrag wird die Bedeutung und Wirkung solcher Migrationsnetzwerke fur die aktuellen Stadtstrukturen von Grosstadten der westeuropaischen Staaten am Beispiel Deutschlands untersucht. Sie begunstigen Segregationserscheinungen in den Einwanderungsstadten, die sich bislang vor allem auf Innenstadtgebiete konzentrierten. In dieser Arbeit werden basierend auf einem mikrookonischen Modell der Stadt Aussagen uber die Veranderung raumlicher Siedlungsmuster in den Einwanderungsstadten dargestellt. Dabei erfahrt die empirische Beobachtung, dass innenstadtgelegene Gebiete mit hohem Migrantenanteilen sich bis zu den Stadtrandern ausweiten, eine theoretische Begrundung.

The use of coherence information from ERS tandem pairs for determining forest stock volume in SIBERIA

Abstract: SAR Interferometry yields coherence maps that have been found useful for forest classification. In this paper the possibility of using coherence information derived from ERS Tandem pairs for estimating growing stock volume of boreal forest is investigated. The problem is that the coherence is not only dependent on land cover, but also on imaging characteristics (baseline), environmental effects (rainfall, wind, frost), and topography. An example is shown in the form of a mosaic of nine ERS coherence images from a region around the Yenisey river in Central Siberia. It is clear that the coherence may change drastically from track to track. Also, the strong influence of topography is evident in the lower part of the image. To study the relationship between forest and radar parameters an extensive data set was built up within the framework of the SIBERIA project, which has the aim to generate large-scale forest maps for Russian foresters using ERS and JERS imagery. Forestry data from 36 test sites, each covering from 20,000 to 100,000 hectares of forested land, were made available. The sites were chosen to represent different forest and vegetation zones. This extensive database provides a good basis for understanding the potential and limitations of using ERS coherence in forestry applications.

Status of the HERA-B vertex detector

Abstract: The HERA-B experiment is a forward magnetic spectrometer with good particle identification for hadrons and leptons designed to study violation of CP symmetry in the neutral B meson system. The silicon vertex detector operates in a high-rate environment similar to the ones expected at LHC. In this paper we report on our R&D on strip detector design, frontend ASICs, mechanical and thermal engineering, low-mass RF shielding of the HERA proton beam and on the status of our reconstruction software. First experiences with last year's installation are discussed.

The HERA-B vertex detector system

Abstract: The HERA-B experiment is being built to measure CP violation in the B-system using internal targets at the HERA proton storage ring at DESY. This paper presents an overview of its vertex detector which – apart from an additional superlayer – is realized by a system of 20 Roman pots containing seven superlayers of double-sided silicon microstrip detectors that are operated at 10 mm distance from the proton beam in a high-radiation environment.

The HERA-B vertex detector: first results from detector commissioning

Abstract: An overview of the design of the HERA-B vertex detector is presented. During the 1998/99 commissioning run 25% of the system was instrumented. First results from this data taking period are shown.

Neuronavigation in der Zentralregion: Bedeutung für einzelne Operationsphasen bei verschiedenen Prozesslokalisationen

Abstract: The neurosurgical treatment of space occupying processes in the central area bears a relatively high risk of either postoperative neurological deficits ("radical approach") or of residual tumor ("conservative approach"). Therefore, special techniques of intraoperative topographic orientation (image-guided surgery) play an important role here. The possible impact of neuronavigation on different neurosurgical steps (craniotomy, corticotomy, localization of the process, definition of borders of resection) was studied in relation to the site of pathology (extraaxial, intraaxial/superficial, intraaxial/deep) in 46 patients harbouring space occupying lesions of the central area. In intraaxial pathologies, additional electrophysiological monitoring was done. It could be shown, that in cases of deep seated processes, neuronavigation had the greatest impact on craniotomy, corticotomy and localization of the process, whereas the borders of resection were defined predominantly on the basis of differences in colour or consistency. In extraaxial pathologies, neuronavigation was of significance only for craniotomy; in intraaxial processes visible at the surface, it had an impact on craniotomy and--in a few cases--on definition of resection borders. In neurosurgery of intraaxial pathologies of the central area (particularly those not visible at the surface), the use of neuronavigation (or another method of intraoperative localization) in combination with neurophysiologic monitoring is strongly recommended.

Tübinger Arbeitspapiere zur Internationalen Politik und Friedensforschung

Abstract: Center for International Relations/ Peace and Conflict Studies, Institute for Political Science, University of Tubingen Address: Melanchthonstr. 36, D-72074 Tubingen Phone: ++49 (0)7071 29-78372 Fax: ++49 (0)7071 29-2417 WWW Homepage: http://www.uni-tuebingen.de/uni/spi/ab2menu.htm © Copyright: H. Breitmeier, V. Rittberger Tubingen 1998 ISBN 3-927604-25-9 Redaktion: Klaus Stodick WWW-Layout: Jurgen Plieninger Tubinger Arbeitspapiere zur Internationalen Politik und Friedensforschung Nr. 32

Information content of ERS SAR interferometric products for forest classification in SIBERIA: a case study over the Bolshemurtinskii forest enterprise

Abstract: Due to their all-weather and day and night capabilities, satellite based Synthetic Aperture Radar (SAR) systems may become an important and relatively cost-efficient source of up-to-date information about Siberian forests. It is the goal of the SIBERIA (SAR Imaging for Boreal Ecology and Radar Interferometry Applications) project to demonstrate the value of these data for Siberian foresters. SIBERIA uses the advantages of dual-frequency, interferometric, and multi-temporal SAR products from the ERS and JERS missions. For each scene of the SIBERLA project area, one ERS tandem pair from fall 1997, one ERS summer image from 1998, and additionally, one JERS image from 1998 are available. To explore the use of the derived SAR products in forest applications and to define a classification methodology a detailed forest inventory data base containing data from more than 36 testsites, with each having a size between 20,000 and 100,000 ha, has been collected. the information content of ERS SAR products (backscattering coefficient, coherence) is investigated over four testsites located in the Bolshemurtinskii forest enterprise. The enterprise is situated in the central part of the Krasnoyarsk Oblast. The forest inventory of these four sites was updated in 1998, so that a good correspondence between the radar and field data is given.

A simple method for transposing MRI information to simulation films. Technical note

Abstract: BACKGROUND The use of MRI information in the treatment planning process is still expensive and time consuming. Electro-optical devices or specially designed post-processing software in here the risk of picture distortion. PATIENTS AND METHODS Between June 1998 and June 1999 in 48 patients with brain tumors and 11 patients with carcinoma of the prostate CT treatment planning and MRI were performed with identical patient positioning using the same devices as in the simulation. The transposition of organ and tumor volumes between MRI and simulation film takes place by overlying both on the brightening screen by using a grid. MRI and simulation films must be produced using an identical magnification factor. RESULTS For 9 patients with brain tumors and 2 patients with a carcinoma of the prostate the transposition of MRI information on the simulation films showed the necessity of a modification of the shielding or the treatment portals. CONCLUSIONS The simple method of direct transposition of MRI structures into simulation films allows to accomplish a verification of the portals and conformation which result of the treatment planning process. Moreover an individualized shielding can also directly be realized.

Intraoperative Radiotherapy in Patients with High-Grade Glioma in Comparison to Conventionally Treated Patients – a Matched-Pair Analysis

Abstract: Summary Background: Controlled clinical trials comparing intra-operative radiotherapy (IORT) and conventional radiotherapy are still missing for patie

A Temperature Time Counter Scheme for the Boltzmann Equation

Abstract: This paper gives a rigorous derivation of a new stochastic particle method for the Boltzmann equation and illustrates its numerical efficiency. Using estimates based on the local temperature of the simulation cells, any truncation error related to large velocities is avoided. Moreover, time steps between collisions are larger than in the standard direct simulation method. This fact and an efficient modelling procedure for the index distribution of the collision partners lead to a considerable reduction of computational effort in certain applications.