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Analysis of future development opportunities for OIS (Office Information Systems) methods and tools.
(1992)
Stereotactic frame systems are widely used in neurosurgery. The accuracy of frame devices is considered as a gold standard to which the accuracy of new frameless stereotactic navigation systems is compared. The purpose of this study is to develop a general approach for the prediction of the application accuracy of stereotactic systems. The approach will be applied to the frame‐based biopsy performed with three frame devices: Leksell G, Cosman–Roberts–Wells (CRW), and Brown–Roberts–Wells (BRW). A work‐flow analysis will be carried out demonstrating that the accuracy relevant for a clinical application comprises several error sources including imaging, target and entry point selection, image to frame coordinates registration, and the setting of mechanical parameters of the frame. These error sources will be postulated to obey a Gaussian distribution probability density. The linear, i.e., Gaussian, error propagation, will be used to link all error contributions thus to calculate the cumulative accuracy of the frame used in the application. Although the Gaussian approach is an approximation, it allows for an analytical treatment of the accuracy. Both the accuracy at the target point and the accuracy of the probe needle guidance along the planned trajectory have been investigated. Of great significance is the relationship found between accuracy, pixel dimension, and image slice thickness, the latter being the dominant factor for slices of more than 1.5 mm thickness, yielding inaccuracies larger than 1.5 mm. For target points the predictions for the application accuracy have been compared to the results of measurements, showing good agreement with the experimental data.
A qualitative work‐flow analysis of a neurosurgical procedure indicates that the resolution of the image used to plan the intervention is the major source of inaccuracy. Quantitative experimental measurements confirm this observation. They fail, however, to explain the relationship between the accuracy of the frame components involved in a stereotactic procedure and the overall application accuracy. This investigation shows that the novel Gaussian approach is a flexible framework for the calculation of the application accuracy of frame systems. Therefore, the Gaussian approach provides a detailed understanding of the interplay between the various factors affecting accuracy. The basic ideas and limitations of the Gaussian approach are briefly explained. The effect of fiducial marker distribution and registration is investigated and shown to introduce a spatial dependence to the accuracy. The results of the Gaussian approach are compared with experimental data for three stereotactic frame devices: Leksell G, Cosman–Roberts–Wells, and Brown–Roberts–Wells. Although the Gaussian approach is an approximation, it reproduces the accuracy measured in the experiment within the statistical error of that experiment. Comp Aid Surg 4:77–86 (1999). © 1999 Wiley‐Liss, Inc.
Three-dimensional magnetic resonance medical images may contain scanner- and patient-induced geometric distortion. For qualitative diagnosis, geometric errors of a few millimeters are often tolerated. However, quantitative applications such as image-guided neurosurgery and radiotherapy can require an accuracy of a millimeter or better. We have developed a method to accurately measure scanner-induced geometric distortion and to correct the MR images for this type of distortion. The method involves a number of steps. First, a specially designed phantom is scanned that contains a large number of reference structures on positions with a manufacturing error of less than 0.05 mm. Next, the positions of the reference structures are automatically detected in the scanned images and a higher-order polynomial distortion-correction transformation is estimated. Then the patient is scanned and the transformation is applied to correct the patient images for the detected distortion. The distortion-correction method is explained in detail in this paper. The accuracy of the method has been measured with synthetically generated phantom scans that contain an exactly-known amount and type of distortion. The reproducibility of the method has been measured by applying it to a series of consecutive phantom scans. Validation results are briefly described in this paper, a more-detailed description is given in another submission to SPIE Medical Imaging 2001.
Geometries, stabilities, electronic properties and NMR-shielding of cucurbit[6]uril–spermine host-ligand complexes are investigated with DFT calculations and compared to experimental results. Cucurbit[6]uril and spermine can form complexes with two different minimum energy geometries and corresponding characteristic differences in NMR shielding. The energetically preferred complex geometry has a perfect inversion symmetry and its proton NMR shielding agrees very well with experimental results. The cucurbit[6]uril host molecule shows a distinct geometrical flexibility in ligand binding which allows an induced fit of the spermine ligand. The energetic barrier for the rotation of spermine in the favourable complex is approximated to be in the order of a few kilocalories per mole.
This paper develops a framework for understanding the relationships between approaches to learning adopted by students in the context of higher education and the culture of the country they were brought up in. The paper, after examining the more widely used Kolb's learning styles, opts for another categorisation, namely the so called learning approaches developed by Entwistle and others (for example, Entwistle and Ramsden, 1983; Biggs, 1987; Entwistle, 1992; Tait, Entwistle and McCune, 1998; Biggs, Kember and Leung, 2001). Each of the main categories of learning approaches identified by his school, namely, deep, surface apathetic, and strategic are related to Hofstede's cultural dimensions, namely, power distance, individualism vs. collectivism, uncertainty avoidance, long vs. short time orientation and masculinity vs. femininity and a series of hypotheses developed that could be tested in cross cultural samples. This study would give practical hints on students moving out to study in different cultures (e.g. for higher education) and for teachers dealing with students from multiple cultures.
(PDF) Does culture influence learning styles in higher education?. Available from: https://www.researchgate.net/publication/254836756_Does_culture_influence_learning_styles_in_higher_education [accessed Jul 09 2018].
Creating chemo- & bioinformatics workflows, further developments within the CDK-Taverna Project
(2008)
It is well-known that protein-modified implant surfaces such as TiO2 show a higher bioconductivity. Fibronectin is a glycoprotein from the extracellular matrix (ECM) with a major role in cell adhesion. It can be applied on titanium oxide surfaces to accelerate implant integration. Not only the surface concentration but also the presentation of the protein plays an important role for the cellular response. We were able to show that TiOX surfaces modified with biotinylated fibronectin adsorbed on a streptavidin-silane self-assembly multilayer system are more effective regarding osteoblast adhesion than surfaces modified with nonspecifically bound fibronectin. The adsorption and conformation behavior of biotinylated and nonbiotinylated (native) fibronectin was studied by surface plasmon resonance (SPR) spectroscopy and atomic force microscopy (AFM). Imaging of the protein modification revealed that fibronectin adopts different conformations on nonmodified compared to streptavidin-modified TiOX surfaces. This conformational change of biotinylated fibronectin on the streptavidin monolayer delivers a fibronectin structure similar to the conformation inside the ECM and therefore explains the higher cell affinity for these surfaces.
The one-phonon inelastic low energy helium atom scattering theory is adapted to cases where the target monolayer is a p(1x1) commensurate square lattice. Experimental data for para-H2/NaCl(001) are re-analyzed and the relative intensities of energy loss peaks in the range 6 to 9 meV are determined. The case of the H2/NaCl(001) monolayer for 26 meV scattering energy is computationally challenging and difficult because it has a much more corrugated surface than those in the previous applications for triangular lattices. This requires a large number of coupled channels for convergence in the wave-packet-scattering calculation and a long series of Fourier amplitudes to represent the helium-target potential energy surface. A modified series is constructed in which a truncated Fourier expansion of the potential is constrained to give the exact value of the potential at some key points and which mimics the potential with fewer Fourier amplitudes. The shear horizontal phonon mode is again accessed by the helium scattering for small misalignment of the scattering plane relative to symmetry axes of the monolayer. For 1° misalignment, the calculated intensity of the longitudinal acoustic phonon mode frequently is higher than that of the shear horizontal phonon mode in contrast to what was found at scattering energies near 10 meV for triangular lattices of Ar, Kr, and Xe on Pt(111).
Hydrogen concentrations in ZnO single crystals exposing different surfaces have been determined to be in the range of (0.02–0.04) at.% with an error of ±0.01 at.% using nuclear reaction analysis. In the subsurface region, the hydrogen concentration has been determined to be higher by up to a factor of 10. In contrast to the hydrogen in the bulk, part of the subsurface hydrogen is less strongly bound, can be removed by heating to 550°C, and reaccommodated by loading with atomic hydrogen. By exposing the ZnO(10-10) surface to water above room temperature and to atomic hydrogen, respectively, hydroxylation with the same coverage of hydrogen is observed.
This report gives a brief overview to the state of the art of PEM fuel cell technology and a description of a newly developed fuel cell stack concept. One main research activity at the Westphalian Energy Institute of the Westphalian University of Applied Sciences is the development of PEM fuel cells, for which a range of different materials have been investigated for fuel cell pole plate construction. Whereas graphite is a material which has suitable properties concerning conductivity as well as manufacturing e.g. for milling, stainless steel foils are suitable for economical hydroforming processes. However, with steel coating is necessary to increase corrosion resistance as well as electrical conductivity. A new fuel cell stack design is currently under development using separated single fuel cells with hydraulic cell compression. The advantages of this stack concept are modularity, effective heat exchanging and constant, uniform cell compression which are further described in this work.
Gaining customer loyalty is an important goal of marketing, and loyalty programs are intended to help in reaching it. Research on loyalty programs suggests that customers differentiate between loyalty to a company and loyalty to a loyalty program, yet little is known about the consequences of these two types of loyalty. Therefore, our study intends to make two main contributions: (1) improving our understanding of the constructs “program loyalty” and “company loyalty”, (2) investigating the relative impact of the two types of loyalty on preference, intention, and purchase behavior for the case of a multi-firm loyalty program. Results indicate that company loyalty influences a customer’s choice to visit a particular provider and to prefer it over competitors, but it is not a strong predictor of purchase behavior. Conversely, program loyalty is a far more important driver of purchase behavior. This implies that company loyalty primarily attracts customers to a particular provider and program loyalty ensures that once inside the store, more money is spent.
Streptavidin-coated TiO2 surfaces are biologically inert: Protein adsorption and osteoblast adhesion
(2012)
Non‐fouling TiO2 surfaces are attractive for a wide range of applications such as biosensors and medical devices, where biologically inert surfaces are needed. Typically, this is achieved by controlled surface modifications which prevent protein adsorption. For example, polyethylene glycol (PEG) or PEG‐derived polymers have been widely applied to render TiO2 surfaces biologically inert. These surfaces have been further modified in order to achieve specific bio‐activation. Therefore, there have been efforts to specifically functionalize TiO2 surfaces with polymers with embedded biotin motives, which can be used to couple streptavidin for further functionalization. As an alternative, here a streptavidin layer was immobilized by self‐assembly directly on a biotinylated TiO2 surface, thus forming an anti‐adhesive matrix, which can be selectively bio‐activated. The anti‐adhesive properties of these substrates were analyzed by studying the interaction of the surface coating with fibronectin, lysozym, and osteoblast cells using surface plasmon resonance spectroscopy, atomic force microscopy, and light microscopy. In contrast to non‐modified TiO2 surfaces, streptavidin‐coated TiO2 surfaces led to a very biologically inert substrate, making this type of surface coating a promising alternative to polymer coatings of TiO2 surfaces.
This paper makes a contribution to the discussion on microfoundations of dynamic capabilities – actions and interactions in organizations that enable continuous organizational renewal. More specifically, we propose the idea that dynamic capabilities of an organization
are a positive function of corresponding dynamic capabilities of individual and collective actors in the organization. Further, we develop the assumption that not only individual acts of managers but also of individuals and teams without managerial responsibility relate to dynamic capabilities of the organization. Following a holistic view, we also take into consideration empowering working conditions as enhancing factor of this function. To
examine these roots of dynamic capabilities, we use a multi level model of competence provided by Wilkens, Keller and Schmette (2006) that operationalizes the concept of dynamic
capabilities provided by Teece (2007) on a concisely behavioural base. We investigated our hypotheses with a standardized questionnaire in a case study of a German plant engineering company with 112 participants and found first support for our assumptions. Our results show an impact of individual dynamic capabilities on dynamic capabilities of the organization which is mediated by team dynamic capabilities. Psychological and social-structural empowerment moderated this relationship. A case-specific interpretation and implications for future research and practice are discussed.
From brain drain to brain exchange: how to use better highly skilled workers; a conceptual approach.
(2012)
The biomodification of surfaces, especially titanium, is an important issue in current biomedical research. Regarding titanium, it is also important to ensure a specific protein modification of its surface because here protein binding that is too random can be observed. Specific nanoscale architectures can be applied to overcome this problem. As recently shown, streptavidin can be used as a coupling agent to immobilize biotinylated fibronectin (bFn) on a TiOX surface. Because of the conformation of adsorbed biotinylated fibronectin on a streptavidin monolayer, it is possible to adsorb more streptavidin and biotinylated fibronectin layers. On this basis, an alternating protein multilayer can be built up. In contrast to common layer-by-layer technology, in this procedure the mechanism of layer adsorption is very specific because of the interaction of biotin and streptavidin. In addition, we showed that the assembly of this multilayer system and its stability are dependent on the degree of labeling of biotinylated fibronectin. Hence we conclude that it is possible to build up well-defined nanoscale protein architectures by varying the degree of labeling of biotinylated fibronectin.