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Search Results: 1 - 10 of 15031 matches for " Christian Siebert "
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Perfectly load-balanced, optimal, stable, parallel merge
Christian Siebert,Jesper Larsson Tr?ff
Computer Science , 2013,
Abstract: We present a simple, work-optimal and synchronization-free solution to the problem of stably merging in parallel two given, ordered arrays of m and n elements into an ordered array of m+n elements. The main contribution is a new, simple, fast and direct algorithm that determines, for any prefix of the stably merged output sequence, the exact prefixes of each of the two input sequences needed to produce this output prefix. More precisely, for any given index (rank) in the resulting, but not yet constructed output array representing an output prefix, the algorithm computes the indices (co-ranks) in each of the two input arrays representing the required input prefixes without having to merge the input arrays. The co-ranking algorithm takes O(log min(m,n)) time steps. The algorithm is used to devise a perfectly load-balanced, stable, parallel merge algorithm where each of p processing elements has exactly the same number of input elements to merge. Compared to other approaches to the parallel merge problem, our algorithm is considerably simpler and can be faster up to a factor of two. Compared to previous algorithms for solving the co-ranking problem, the algorithm given here is direct and maintains stability in the presence of repeated elements at no extra space or time cost. When the number of processing elements p does not exceed (m+n)/log min(m,n), the parallel merge algorithm has optimal speedup. It is easy to implement on both shared and distributed memory parallel systems.
Injury rates of the German Women’s American Football National Team from 2009 to 2011
Marco Ezechieli,Stephan Berger,Christian-Heige Siebert,Oliver Miltner
Orthopedic Reviews , 2012, DOI: 10.4081/or.2012.e28
Abstract: American football is one of the leading causes of athletic-related injuries. Injury rates in female elite players are mostly unknown. We hypothesized that the injury rates of female was comparable to those in men’s football during practice, as well as games. From 2009 to 2011, injury data were collected from the German female national team during training camps, World Championship 2010 and International friendly matches. The injury was categorized by location on the body and recorded as fracture/dislocation, strain, concussion, contusion or other injury. Injury rates were determined based on the exposure of an athlete to a game or practice event. The injury rate was calculated as the ratio of injuries per 1000 athlete exposures (AE). The rate of injury was significantly higher during games (58.8/1000 AE) than practices [16.3/1000 AE, (P<0.01)]. Furthermore, the injury rate in the tryouts was significantly higher (24.05/1000 AE) compared to other training sessions with the national team (11.24/1000 AE). Our findings show that the injury rates in female elite American football players can be compared to those described for male players. Higher injury rates during matches than in training should also be underlined.
In silico Study on Sulfated and Non-Sulfated Carbohydrate Chains from Proteoglycans in Cnidaria and Interaction with Collagen  [PDF]
Thomas Eckert, Sabine St?tzel, Monika Burg-Roderfeld, Judith Sewing, Thomas Lütteke, Nikolay E. Nifantiev, Johannes F. G. Vliegenthart, Hans-Christian Siebert
Open Journal of Physical Chemistry (OJPC) , 2012, DOI: 10.4236/ojpc.2012.22017
Abstract: Proteoglycans and collagen molecules are interacting with each other thereby forming various connective tissues. The sulfation pattern of proteoglycans differs depending on the kind of tissue and/or the degree of maturation. Tissues from Cnidaria are suitable examples for exploration of the effects in relation to the presence and the absence of sulfate groups, when studying characteristic fragments of the long proteoglycan carbohydrate chains in silico. It has been described that a non-sulfated chondroitin appears as a scaffold in early morphogenesis of all nematocyst types in Hydra. On the other hand, sulfated glucosaminoglycans play an important role in various developmental processes of Cnidaria. In order to understand this biological phenomenon on a sub-molecular level we have analysed the structures of sulfated and non-sulfated proteoglycan carbohydrate chains as well as the structure of diverse collagen molecules with computational methods including quantum chemical calculations. The strong interactions between the sulfate groups of the carbohydrates moieties in proteoglycans and positively charged regions of collagen are essential in stabilizing various Cnidaria tissues but could hinder the nematocyst formation and its proper function. The results of our quantum chemical calculations show that the sulfation pattern has a significant effect on the conformation of chondroitin structures under study.
Breast cancer incidence and mortality in Tyrol/Austria after fifteen years of opportunistic mammography screening
Willi Oberaigner, Wolfgang Buchberger, Thomas Frede, Rudolf Knapp, Christian Marth, Uwe Siebert
BMC Public Health , 2010, DOI: 10.1186/1471-2458-10-86
Abstract: To study time trends in breast cancer incidence and mortality, we applied the age-period-cohort model by Poisson regression to the official mortality data covering more than three decades from 1970 to 2006 and to the incidence data ranging from 1988 to 2006. In addition, for incidence data we analysed data on breast cancer staging and compared these with EU guidelines.For the analysis of time trend in breast cancer mortality in age groups 40-79, an age-period-cohort model fits well and shows for years 2002-2006 a statistically significant reduction of 26% (95% CI 13%-36%) in breast cancer mortality as compared to 1992-1996.We see only slight non-significant increases in breast cancer incidence. For the past five years, incidence data show a 10% proportion of in situ cases, and of 50% for cases in stages II+.The opportunistic breast cancer screening programme in Tyrol has only in part exploited the mortality reduction known for organised screening programmes. There seems to be potential for further improvement, and we recommend that an organised screening programme and a detailed screening database be introduced to collect all information needed to analyse the quality indicators suggested by the EU guidelines.Breast cancer (BC) is the leading cause of female cancer death in all industrialised countries (and also worldwide) and the breast is also the leading incident cancer site for females [1]. Therefore, screening methods for BC are of greatest public health importance. Efficiency and efficacy of organised mammography screening programmes have been proven in large randomised trials conducted in Europe and North America. For several years already, organised mammography screening programmes have been recommended in the EU[2]. Austria is one of the European countries where up to 2006 no organised programmes were implemented, but where coverage in spontaneous mammography screening could have been rather high. In a micro-census conducted in Austria in 2006-2007, more tha
Introduction of organised mammography screening in tyrol: results of a one-year pilot phase
Willi Oberaigner, Wolfgang Buchberger, Thomas Frede, Martin Daniaux, Rudolf Knapp, Christian Marth, Uwe Siebert
BMC Public Health , 2011, DOI: 10.1186/1471-2458-11-91
Abstract: In June 2007, the system of opportunistic mammography screening in Tyrol was changed to an organised system by introducing a personal invitation system, a training program, a quality assurance program and by setting up a screening database. All procedures are noted in a written protocol. Most EU recommendations for organised mammography screening were followed, except double reading. All women living in Tyrol and covered by social insurance are now invited for a mammography, in age group 40-59 annually and in age group 60-69 biannually. Screening mammography is offered mainly by radiologists in private practice. We report on the results of the first year of piloting organised mammography screening in two counties in Tyrol.56,432 women were invited. Estimated participation rate was 34.5% at one year of follow-up (and 55.5% at the second year of follow-up); 3.4% of screened women were recalled for further assessment or intermediate screening within six months. Per 1000 mammograms nine biopsies were performed and four breast cancer cases detected (N = 68). Of invasive breast cancer cases 34.4% were ≤ 10 mm in size and 65.6% were node-negative. In total, six interval cancer cases were detected during one year of follow-up; this is 19% of the background incidence rate.In the Tyrolean breast cancer screening program, a smooth transition from a spontaneous to an organised mammography screening system was achieved in a short time and with minimal additional resources. One year after introduction of the screening program, most of the quality indicators recommended by the European guidelines had been reached.However, it will be necessary to introduce double reading, to change the rule for BI-RADS 3, and to concentrate on actions toward improving the participation rate.Breast cancer is the leading cause of female cancer death in all industrialised countries (and also worldwide), and the breast is also the leading incident cancer site for females [1]. Therefore, screening metho
Collagen Metabolism of Human Osteoarthritic Articular Cartilage as Modulated by Bovine Collagen Hydrolysates
Saskia Schadow, Hans-Christian Siebert, Günter Lochnit, Jens Kordelle, Markus Rickert, Jürgen Steinmeyer
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0053955
Abstract: Destruction of articular cartilage is a characteristic feature of osteoarthritis (OA). Collagen hydrolysates are mixtures of collagen peptides and have gained huge public attention as nutriceuticals used for prophylaxis of OA. Here, we evaluated for the first time whether different bovine collagen hydrolysate preparations indeed modulate the metabolism of collagen and proteoglycans from human OA cartilage explants and determined the chemical composition of oligopeptides representing collagen fragments. Using biophysical techniques, like MALDI-TOF-MS, AFM, and NMR, the molecular weight distribution and aggregation behavior of collagen hydrolysates from bovine origin (CH-Alpha?, Peptan? B 5000, Peptan? B 2000) were determined. To investigate the metabolism of human femoral OA cartilage, explants were obtained during knee replacement surgery. Collagen synthesis of explants as modulated by 0–10 mg/ml collagen hydrolysates was determined using a novel dual radiolabeling procedure. Proteoglycans, NO, PGE2, MMP-1, -3, -13, TIMP-1, collagen type II, and cell viability were determined in explant cultures. Groups of data were analyzed using ANOVA and the Friedman test (n = 5–12). The significance was set to p≤0.05. We found that collagen hydrolysates obtained from different sources varied with respect to the width of molecular weight distribution, average molecular weight, and aggregation behavior. None of the collagen hydrolysates tested stimulated the biosynthesis of collagen. Peptan? B 5000 elevated NO and PGE2 levels significantly but had no effect on collagen or proteoglycan loss. All collagen hydrolysates tested proved not to be cytotoxic. Together, our data demonstrate for the first time that various collagen hydrolysates differ with respect to their chemical composition of collagen fragments as well as by their pharmacological efficacy on human chondrocytes. Our study underscores the importance that each collagen hydrolysate preparation should first demonstrate its pharmacological potential both in vitro and in vivo before being used for both regenerative medicine and prophylaxis of OA.
Airborne Thermal Data Identifies Groundwater Discharge at the North-Western Coast of the Dead Sea
Ulf Mallast,Friedhelm Schwonke,Richard Gloaguen,Stefan Geyer,Martin Sauter,Christian Siebert
Remote Sensing , 2013, DOI: 10.3390/rs5126361
Abstract: A qualitative and quantitative monitoring of groundwater discharge was conducted based on an airborne thermal campaign undertaken along the north-western coast of the Dead Sea in January 2011 to contribute to the relatively scarce information on groundwater discharge to date in the region. The application of airborne thermal data exploits thermal contrasts that exist between discharging groundwater and background sea surface temperatures of the Dead Sea. Using these contrasts, 72 discharge sites were identified from which only 42 were known from previous in situ measurements undertaken at terrestrial springs by the Israel Hydrological Service. Six of these sites represent submarine springs and at a further 24 locations groundwater appears to seep through the sediment. Although the abundance of groundwater seepage sites suggests a significant, but so far unknown groundwater source, the main contribution appears to originate from terrestrial springs. In an attempt to provide a quantitative approach for terrestrial springs, a linear bootstrap regression model between in situ spring discharge and respective thermal discharge plumes (r 2 = 0.87 p < 0.001) is developed and presented here. While the results appear promising and could potentially be applied to derive discharge values at unmonitored sites, several influence factors need to be clarified before a robust and reliable model to efficiently derive a complete quantitative picture of groundwater discharge can be proposed.
Using decision-analytic modelling to transfer international evidence from health technology assessment to the context of the German health care system
Siebert, Uwe
GMS Health Technology Assessment , 2005,
Abstract: The objective of this Health Technology Assessment (HTA) methods report was to examine and to assess decision analysis (DA) as a method to transfer and adapt international scientific evidence in HTA to the German health care context. Furthermore, we sought to develop a systematic framework to facilitate the selection, transfer, adaptation, and synthesis of these data in German HTA projects. In this report, we review and summarise the concepts and methods of DA; present potential areas of applications, and provide a basis for the critical assessment of decision-analytic studies. The two main methods of DA, decision trees and Markov models, as well as various approaches to sensitivity analyses are described. Examples of typical situations for the use of DA in scientific evidence transfer are described, and a list of main health care domains and parameters in evidence transfer is presented. Finally, we developed a framework to transfer and apply international evidence to the national health care context. The strengths and limitations of the decision-analytic approach are critically examined. In summary, this HTA report describes different situations, in which decision-analytic models can be useful, and demonstrates the utility of DA in transferring and applying international evidence to the national health care context. We developed a systematic instrument to transfer international evidence to the context of other countries and successfully applied this instrument in two German HTA projects. The use of this instrument is recommended in further HTA projects dealing with the application of international evidence to the German health care context. The use of decision-analytic models to transfer international evidence is endorsed. However, the limitations of DA should be clearly stated discussed transparently in all HTA reports.
ARRANJOS INSTITUCIONAIS E TRAJETóRIA DO PLANEJAMENTO TERRITORIAL EM SANTA CATARINA Institutional Arrangements and Trajectory of Planning in Santa Catarina Arreglos Institucionales y Circunstancias de la Planificación en Santa Catarina
Claudia Siebert
Revista Paranaense de Desenvolvimento , 2010,
Abstract: Português Santa Catarina tem sido um laboratório de experiências de novas institucionalidades e deplanejamento territorial. De forma descontínua, o Estado contou com AssociativismoMunicipal, Fóruns de Desenvolvimento Regional, Regi es Metropolitanas, Comitês deGerenciamento de Bacias Hidrográficas e Secretarias de Desenvolvimento Regional. Este artigoprocura contribuir para o conhecimento sobre os arranjos institucionais descentralizados e oplanejamento, resgatando parte da memória do planejamento em Santa Catarina. Inicialmente,abordam-se os diversos arranjos institucionais do Estado. A seguir, analisa-se o planejamento,com a consulta aos originais dos planos territoriais de 1979 a 2011, e se entrevistam ostécnicos envolvidos na elabora o desses planos, que relataram, em primeira m o, suaexperiência no processo. Ficou evidenciada a descontinuidade no processo de planejamentoregional e de gest o do território em Santa Catarina, com avan os e retrocessos tanto naquest o ambiental quanto na participa o de atores n o governamentais.English Santa Catarina has been a laboratory for experimentation with new institutions and territorialplanning. Discontinuously, the state relied on Municipal Associations, Regional DevelopmentBoards, Metropolitan Regions, Committees of Watershed Management and Departments forRegional Development. This article search for contribute to the knowledge about the institutionalarrangements and the decentralized planning in the state, rescuing the memory of planningin Santa Catarina. Initially, we approach the various institutional arrangements of the State.After that, we discussed the planning in the State, consulting the original territorial plans,from 1979 to 2011, and interviewed the technicians involved in drafting these plans, that reporting firsthand experience in the process. Evidence was found of discontinuity in theprocess of regional planning and land management in Santa Catarina, with advances andsetbacks in both environmental issues and the participation of non-state actors.Espa ol Santa Catarina ha sido un laboratorio de experiencias de nuevas instituciones y de planificaciónterritorial. Discontinuamente, el Estado tuvo Asociaciones Municipales, Consejos Regionalesde Desarrollo, Regiones Metropolitanas, Comités de Manejo de Cuencas Hidrográficas yDepartamentos para el Desarrollo Regional. Ese artículo busca contribuir al conocimiento delos arreglos institucionales descentralizados y la planificación en el Estado, con el rescate dela memoria por parte de la planificación en Santa Catarina. Inicialmente, se dirigió a losd
Dynamical and Structural Modularity of Discrete Regulatory Networks
Heike Siebert
Electronic Proceedings in Theoretical Computer Science , 2009, DOI: 10.4204/eptcs.6.8
Abstract: A biological regulatory network can be modeled as a discrete function that contains all available information on network component interactions. From this function we can derive a graph representation of the network structure as well as of the dynamics of the system. In this paper we introduce a method to identify modules of the network that allow us to construct the behavior of the given function from the dynamics of the modules. Here, it proves useful to distinguish between dynamical and structural modules, and to define network modules combining aspects of both. As a key concept we establish the notion of symbolic steady state, which basically represents a set of states where the behavior of the given function is in some sense predictable, and which gives rise to suitable network modules. We apply the method to a regulatory network involved in T helper cell differentiation.
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