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Search Results: 1 - 10 of 1935 matches for " Norbert Feinendegen "
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Was man vom Teufel lernen kann. Gedanken zu einem Buch von C. S. Lewis
Norbert Feinendegen
Aemaet , 2013, DOI: urn:nbn:de:0288-20120612229
Abstract: Die Ratschl ge des Teufels; Verdrehung des Guten; Flucht vor der Wahrheit; Was der Teufel nicht versteht; Vertrauen in die Liebe Gottes
The Impact of Thermal Modeling on Limiting RF-EMF  [PDF]
Norbert Leitgeb
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.54022

The paper quantitatively assesses the relationship between specific energy absorption rates (SAR) of radio frequency (RF) electromagnetic fields (EMF) and resulting intracorporal tissue temperature changes (ΔT) at whole body exposure of a small person to resonant RF EMF. Applied thermal modeling allowed accounting also for dynamic thermoregulatory responses. As expected from physical laws the correlation of all local SAR values and ΔT data was fairly good. However, at local level SAR proved to be only weakly associated with ΔT. Even if averaged, over any 10 g tissue the ratio ΔT10g/SAR10g still varied by almost two orders of magnitudes. Blood perfusion was found to play a major role in affecting local temperature changes and caused even net cooling. The results demonstrate that local SAR is a poor surrogate for local temperature change, and that conventional static thermal modeling underestimates body core temperature. Results demonstrated that recommended reference levels of RF EMF fail to reliably prevent from exceeding yet legally binding basic restrictions not only with regard to whole-body SAR

Improved diagnosis of human joint  [PDF]
Norbert Leitgeb
Open Journal of Clinical Diagnostics (OJCD) , 2013, DOI: 10.4236/ojcd.2013.34030
Abstract: Today, among the general population the prevalence of joint disorders is increasing even at younger ages. Since therapeutic means are sparse, early awareness of potential health problems is the most important to timely start adequate prevention. The presented improved approach of acoustic joint assessment (ACOJA) is based on subsequently measured acoustic signals emitted by joints at two different mechanical load conditions with the same measurement setup, and analysing the related relative spectral signal changes. While this approach applies to almost any joint, this paper concentrates on demonstrating the capability of this approach at hip joints. It could be demonstrated that the ACOJA method is sensible enough to allow even quantification of age-related degradations at hip normal biological human joints. It allows even identifying and accounting for gender-related differences in hip joint status. This allows concluding that ACOJA will contribute to enlarge the medical possibilities of non-invasive joint diagnostics.
Synoptic Analysis of Epidemiologic Evidence of Brain Cancer Risks from Mobile Communication  [PDF]
Norbert Leitgeb
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2014, DOI: 10.4236/jemaa.2014.614043
Abstract: In the radio frequency (RF) range concern about long-term health risks from electromagnetic fields (EMF) is enhanced by contradictory results and conclusions from epidemiologic studies. A new approach of a synoptic analysis of all available data from epidemiological studies published since 2001 was performed. This approach provided new insight with regard to a potential link between mobile phone use and brain cancer. Two quite different data pools could be identified with numerous studies from one research group opposing all other studies. However, it could be shown that with the number of exposed cases both data pools exhibit a clear trend of risk estimates (odds ratios) towards the final result, namely a reduced cancer risk of OR = 0.8, though from either side of the zero-risk line. The analysis of potential long-term effects indicated by a dosedependence revealed diverging results with different dose metrics. Overall, the synoptic analysis supports reassuring rather than alarming conclusions on RF EMF health risks from mobile telecommunication.
Childhood Leukemia Not Linked with ELF Magnetic Fields  [PDF]
Norbert Leitgeb
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2014, DOI: 10.4236/jemaa.2014.67017

The discussion whether extremely low frequency (ELF) magnetic fields (MF) are causally linked with childhood leukemia is ongoing for almost four decades. Results of epidemiologic studies have indicated such an association might exist and led to IARC’s classification of ELF MF as possibly carcinogenic (class 2B). Although in the meanwhile many epidemiologic studies and meta-analyses of selected studies are available, this did not change the situation. By a new approach of pooling all epidemiologic data, this paper shows that it is possible to come to a convincing conclusion which explains controversial results and reports dose-response relationship, and provides answers to striking facts such as that epidemiologic results on childhood leukemia are independent from field source or exposure metric of whatever kind with no specific favorite. The analysis revealed that the assumption of a causal link between ELF MF exposure and childhood leukemia is no longer plausible and hence that ELF MF’s classification as possibly carcinogenic needs revision.

Synoptic Analysis of Epidemiologic Evidence of Glioma Risk from Mobile Phones  [PDF]
Norbert Leitgeb
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2015, DOI: 10.4236/jemaa.2015.79025
Abstract: Concern about brain cancer risks from mobile phone use, in particular of glioma, is mainly based on epidemiologic studies reporting on an increased risk estimate (odds ratio, OR) in particular of long-term and/or heavy users. Concern is enhanced by contradictory results and alarming conclusions from some epidemiologic studies. In a new synoptic approach all reported data from epidemiological studies published since 2001 were analyzed. This approach provided new insight with regard to the suspected link between mobile phone use and glioma. Two quite different data pools could be identified with numerous studies from one single research group opposing all other national and international studies. It could be shown that in spite of puzzling differences of their data pattern, in dependence of the number of exposed cases both data pools exhibit the similar trend of ORs towards reduced glioma risk with increasing statistical power, finally even converging towards a reduced risk, although from either side of the zero-risk line. While in the pooled data a potential long-term risk could be masked by reassuring short-term data the synoptic analysis in dependence of dose surrogates such as cumulated use time, cumulated call time or cumulated number of calls the seemingly increased long-term risk of glioma could be identified as an effect from low statistical power. In spite of worrying differences among some epidemiological studies, overall, the synoptic analysis of the entire body of data supports reassuring rather than alarming conclusions on glioma risks from mobile phone use even in long-term and/or heavy users.
Synoptic Analysis Clarifies Childhood Leukemia Risk from ELF Magnetic Field Exposure  [PDF]
Norbert Leitgeb
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2015, DOI: 10.4236/jemaa.2015.710026
Abstract: In spite of 36 years epidemiologic research, there is still an ongoing controversy about a causal link between childhood leukemia (CL) and exposure to extremely low frequency (ELF) magnetic fields (MF). Public concern has been increased by the fact that ELF MF have been classified as possibly carcinogenic to humans (class 2B) while exposure limits still remain three orders of magnitudes above reported CL risk onset levels. In a new synoptic approach rather than few selected ORs, all reported epidemiological risk estimates (ORs) are analyzed, both pooled together as well as separated into sub-pools of different exposure metric as well as of high and low exposure levels. The results explain the worrying offset of ORs towards increased CL risk as well as the reported puzzling dose-response at low MF levels as an artifact caused by the small-number effect. The synoptic analysis clarifies that ORs critically depend on statistical power. With increasing statistical power ORs decrease and finally converge to and stay at zero risk. This is found consistently at the entire data pool as well as at all sub-pools related to investigated exposure parameters (wire code, distance to MF source, and magnetic field value). Former contradictory results can now be explained. The synoptic analysis provides convincing evidence that the risk of childhood leukemia is not increased by exposure to ELF magnetic fields. IARC’s classification of ELF MF needs revision.
Learn More about Your Data: A Symbolic Regression Knowledge Representation Framework  [PDF]
Ingo Schwab, Norbert Link
International Journal of Intelligence Science (IJIS) , 2012, DOI: 10.4236/ijis.2012.224018
Abstract: In this paper, we propose a flexible knowledge representation framework which utilizes Symbolic Regression to learn and mathematical expressions to represent the knowledge to be captured from data. In this approach, learning algorithms are used to generate new insights which can be added to domain knowledge bases supporting again symbolic regression. This is used for the generalization of the well-known regression analysis to fulfill supervised classification. The approach aims to produce a learning model which best separates the class members of a labeled training set. The class boundaries are given by a separation surface which is represented by the level set of a model function. The separation boundary is defined by the respective equation. In our symbolic approach, the learned knowledge model is represented by mathematical formulas and it is composed of an optimum set of expressions of a given superset. We show that this property gives human experts options to gain additional insights into the application domain. Furthermore, the representation in terms of mathematical formulas (e.g., the analytical model and its first and second derivative) adds additional value to the classifier and enables to answer questions, which sub-symbolic classifier approaches cannot. The symbolic representation of the models enables an interpretation by human experts. Existing and previously known expert knowledge can be added to the developed knowledge representation framework or it can be used as constraints. Additionally, the knowledge acquisition framework can be repeated several times. In each step, new insights from the search process can be added to the knowledge base to improve the overall performance of the proposed learning algorithms.
Retrospective Analysis of the Performance of a New-Generation Dual Pump Phaco System Using Two Sizes of Phaco Tips in Cases with Different Nuclear Hardness  [PDF]
Norbert K?rber
Open Journal of Ophthalmology (OJOph) , 2016, DOI: 10.4236/ojoph.2016.63019
Abstract: Purpose: To evaluate the performance of a phacoemulsification system in terms of effective (EPT) and total phaco time (TPT) using 20G and 21G phaco tips. Methods: Retrospective comparative study including 143 consecutive cataractous eyes undergoing phacoemulsification cataract surgery with the Visalis 500 device. The 20G and 21G phaco tips were used in 46 and 97 eyes, respectively. The EPT and TPT values were evaluated. Results: Median TPT was 11.25 s and 17.50 s in the 20G and 21G groups, respectively (p = 0.0011). Median EPT values were 3.15 s and 5.00 s in the 20G and 21G groups, respectively (p = 0.0032). TPT and EPT were significantly lower in 3/3+ cataract eyes compared to 4/4+ using both tips (p < 0.001). Conclusions: The Visalis 500 allows cataract surgery with reduced TPT and EPT, even in hard cataracts. The use of the 20G phaco tip provides an additional benefit in terms of reduction of phaco time.
Current Concepts in Bone Graft Substitutes  [PDF]
Marie Leteve, Norbert Passuti
New Journal of Glass and Ceramics (NJGC) , 2018, DOI: 10.4236/njgc.2018.83004
Abstract: Purpose: Bone grafting is still requested to fill bone defects in traumatology, or after tumor removal, but also in orthopedic surgery for spine, arthroplasty revisions, and osteotomies. Due to the limitations of autografts and allografts, and the progress of biomaterial research, a large number of nonhuman bony scaffolds have been developed including synthetic calcium phosphates and highly processed xenografts. The most important parameters for bone ingrowth are the macroporosity of the scaffold with the suitable biological autologous cells and factors, optimal osteoinductive, osteointegrative and osteoconductive properties can be achieved. Methods and Results: The important factors regulating these properties are discussed in this paper, which also reports preclinical and clinical results obtained with such bone graft substitutes. Conclusions: Among different bone graft substitutes available, the porosity, the accessibility of pores, the internal surface exposed to the biological components of bone repair, are present in highly processed bovine hydroxyapatites. Compared to autografts, allografts and synthetic substitutes, they associate an initial conductivity, and a long term stability suitable for some orthopedic indications.
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