An enterprise architecture framework for multi-attribute information systems analysis

Enterprise architecture is a model-based IT and business management discipline. Enterprise architecture analysis concerns using enterprise architecture models for analysis of selected properties to provide decision support. This paper presents a framework based on the ArchiMate metamodel for the assessment of four properties, viz., application usage, system availability, service response time and data accuracy. The framework integrates four existing metamodels into one and implements these in a tool for enterprise architecture analysis. The paper presents the overall metamodel and four viewpoints, one for each property. The underlying theory and formalization of the four viewpoints is presented. In addition to the tool implementation, a running example as well as guidelines for usage makes the viewpoints easily applicable.     

Automatic data collection for enterprise architecture models

Enterprise Architecture (EA) is an approach used to provide decision support based on organization-wide models. The creation of such models is, however, cumbersome as multiple aspects of an organization need to be considered, making manual efforts time-consuming, and error prone. Thus, the EA approach would be significantly more promising if the data used when creating the models could be collected automatically—a topic not yet properly addressed by either academia or industry. This paper proposes network scanning for automatic data collection and uses an existing software tool for generating EA models (ArchiMate is employed as an example) based on the IT infrastructure of enterprises. While some manual effort is required to make the models fully useful to many practical scenarios (e.g., to detail the actual services provided by IT components), empirical results show that the methodology is accurate and (in its default state) require little effort to carry out.     

An architecture modeling framework for probabilistic prediction

In the design phase of business and IT system development, it is desirable to predict the properties of the system-to-be. A number of formalisms to assess qualities such as performance, reliability and security have therefore previously been proposed. However, existing prediction systems do not allow the modeler to express uncertainty with respect to the design of the considered system. Yet, in contemporary business, the high rate of change in the environment leads to uncertainties about present and future characteristics of the system, so significant that ignoring them becomes problematic. In this paper, we propose a formalism, the Predictive, Probabilistic Architecture Modeling Framework (P²AMF), capable of advanced and probabilistically sound reasoning about business and IT architecture models, given in the form of Unified Modeling Language class and object diagrams. The proposed formalism is based on the Object Constraint Language (OCL). To OCL, P²AMF adds a probabilistic inference mechanism. The paper introduces P²AMF, describes its use for system property prediction and assessment and proposes an algorithm for probabilistic inference.     

Improved compressed sensing reconstruction for $$^{19}$$ F magnetic resonance imaging

Magnetic Resonance Materials in Physics, Biology and Medicine - In magnetic resonance imaging (MRI), compressed sensing (CS) enables the reconstruction of undersampled sparse data sets. Thus,...     

Poly(L‐lysine)/microcrystalline cellulose biocomposites for porous scaffolds

The need for tissue engineered scaffolds is growing due to a shortage in organ donation, potential immunoreactions to allotransplants, and high cost associated with transplantation. The main focus of this research is concerned with material selection and processing which are key for a successful design of any tissue engineered structure. This work investigates the possibility of reinforcing a weak polypeptide [poly(L ‐lysine)] with a stronger polysaccharide (cellulose) and processing the resulting composite into a porous structure. As the main processing parameters, the effect of pH on the secondary structure of the polypeptide and the effect of the hydrolysis conditions on the properties of commercially available microcrystalline cellulose (MCC) were studied. The significance of the cellulose content as well as the scaffold fabrication conditions on the properties of the composite system was assessed. Overall, PLL/MCC composites showed a lower crystallinity compared to the PLL alone while further hydrolyzed MCC particles (HMCC) showed surface erosion and resulted in a crystallinity increase when incorporated into a composite structure. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Electrospun poly(D,L)‐lactide nonwoven mats for biomedical application: Surface area shrinkage and surface entrapment

Nanofibrous poly(D,L )‐lactide mats prepared by electrospinning are useful for numerous biomedical applications. However, it was observed that these mats tend to shrink under physiological conditions. In this research, a physical entrapment method to modify the polymer surface with poly(ethylene glycol) was developed to ensure dimensional stability and to increase the hydrophilicity of the surface of the mats. Nanofiber morphology was characterized by scanning electron microscopy. Surface element analysis was performed by high resolution X‐ray photoelectron spectroscopy. Water contact angles were determined to identify surface properties before and after surface entrapment. Canine fibroblasts were prepared and seeded onto the poly(D,L)‐lactide mats, followed by cell morphology study by SEM and cell viability tests by MTT assay, which confirmed the improvement of biocompatibility by surface modification. Taking the results into account, hydrophilic and area‐stable nanofibrous nonwoven mats were successfully produced, with potential applications as in vivo biomedical material. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fiber formation by dehydration‐induced aggregation of albumin

Many proteins are capable of forming fibrils in vitro, suggesting that the propensity for fiber formation is a generic property of polypeptides. Pathways leading to fibril assembly, however, still remain elusive. In this research, dehydration of bovine serum albumin (BSA) solutions was found to result in spontaneous and organized formation of densely packed fibrils with the majority of proteins converted to parallel β‐sheets. BSA aggregation was investigated in regard to drying conditions (airflow, temperature, and humidity) and the influence of pH, presence of anions, and protein concentration. Aggregates were prepared at large scale and crosslinked to produce water‐insoluble fibers with mechanical properties comparable to those of silk. Interactions between BSA and salts suggest that removing the inner water shell surrounding globular proteins leads to protein unfolding and aggregation at the water/air interface. BSA fibers can be formed into larger assemblies such as yarns, and dyed with acid dyes, thus showing great potential for future industrial‐scale applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Thermoresponsive hydrogels from BSA esterified with low molecular weight PEG

Bovine serum albumin (BSA) and low molecular weight polyethylene glycol (PEG) were reacted in a single‐step reaction to synthesize translucent hydrogels with a sol–gel transition at temperatures between 37 and 40°C. Gelation occurred by aggregation of smaller assemblies of BSA–PEG precursors within minutes. The sol–gel transition concentration depended on the molecular weight of PEG only at temperatures below 35°C; above 45°C phase separation occurred and a precipitate formed. Microscopic examination showed the porous structure of the gels. At a fairly low grafting ratio, BSA preserved its native secondary and tertiary structure and maintained its capability for binding and enclosing small molecules. Drug delivery was assessed by a discontinuous method in vitro using 5‐fluorouracil. Degradation tests with trypsin confirmed that the hydrogels were biodegradable. This novel material holds promise for biomedical applications as potentially injectable drug delivery vehicle. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40946.     

Vessel radius mapping in an extended model of transverse relaxation

Objectives

Spin dephasing of the local magnetization in blood vessel networks can be described in the static dephasing regime (where diffusion effects may be ignored) by the established model of Yablonskiy and Haacke. However, for small capillary radii, diffusion phenomena for spin-bearing particles are not negligible.

Material and methods

In this work, we include diffusion effects for a set of randomly distributed capillaries and provide analytical expressions for the transverse relaxation times T2* and T2 in the strong collision approximation and the Gaussian approximation that relate MR signal properties with microstructural parameters such as the mean local capillary radius.

Results

Theoretical results are numerically validated with random walk simulations and are used to calculate capillary radius distribution maps for glioblastoma mouse brains at 9.4 T. For representative tumor regions, the capillary maps reveal a relative increase of mean radius for tumor tissue towards healthy brain tissue of \(128 \pm 23 \%\) (p < 0.001).

Conclusion

The presented method may be used to quantify angiogenesis or the effects of antiangiogenic therapy in tumors whose growth is associated with significant microvascular changes.

     

Semi‐interpenetrating polymer network hydrogels based on aspen hemicellulose and chitosan: Effect of crosslinking sequence on hydrogel properties

Semi‐interpenetrating network hydrogel films were prepared using hemicellulose and chemically crosslinked chitosan. Hemicellulose was extracted from aspen by using a novel alkaline treatment and characterized by HPSEC, and consisted of a mixture of high and low molecular weight polymeric fractions. HPLC analysis of the acid hydrolysate of the hemicellulose showed that its major constituent sugar was xylose. X‐ray analysis showed that the relative crystallinity of hydrogels increased with increasing hemicellulose content up to 31.3%. Strong intermolecular interactions between chitosan and hemicellulose were evidenced by FT‐IR analysis. Quantitative analysis of free amino groups showed that hemicellulose could interrupt the chemical crosslinking of chitosan macromolecules. Mechanical testing and swelling experiments were used to define the effective network crosslink density and average molecular weight between crosslinks. Swelling ratios increased with increasing hemicellulose content and mainly consisted of H‐bonded bound water. Results revealed that by altering the hydrogel preparation steps and hemicellulose content, crosslink density and swelling behavior of semi‐IPN hydrogels could be controlled without deteriorating their mechanical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012