Assessment of hemodynamic conditions in the aorta following root replacement with composite valve-conduit graft

This paper presents the analysis of detailed hemodynamics in the aortas of four patients following replacement with a composite bio-prosthetic valve-conduit. Magnetic resonance image-based computational models were set up for each patient with boundary conditions comprising subject-specific three-dimensional inflow velocity profiles at the aortic root and central pressure waveform at the model outlet. Two normal subjects were also included for comparison. The purpose of the study was to investigate the effects of the valve-conduit on flow in the proximal and distal aorta. The results suggested that following the composite valve-conduit implantation, the vortical flow structure and hemodynamic parameters in the aorta were altered, with slightly reduced helical flow index, elevated wall shear stress and higher non-uniformity in wall shear compared to normal aortas. Inter-individual analysis revealed different hemodynamic conditions among the patients depending on the conduit configuration in the ascending aorta, which is a key factor in determining post-operative aortic flow. Introducing a natural curvature in the conduit to create a smooth transition between the conduit and native aorta may help prevent the occurrence of retrograde and recirculating flow in the aortic arch, which is particularly important when a large portion or the entire ascending aorta needs to be replaced

A materials perspective on the design of damage-resilient artificial bones and bone implants through additive/advanced manufacturing

After more than five decades of research, the failure of bone implants is still an issue that becomes increasingly urgent to solve in our ageing population. Among the reasons for failure, catastrophic brittle fracture is one event that is directly related to the implant s material and fabrication and that deserves more attention. Indeed, clinically available implants pale at reproducing the hierarchical and heterogeneous microstructural organization of our natural bones, ultimately failing at reproducing their mechanical strength and toughness. Nevertheless, the recent advances in additive and advanced manufacturing open new horizons for the fabrication of biomimetic bone implants, challenging at the same time their characterization, testing and modelling. This critical review covers selected recent achievements in bone implant research from a materials standpoint and aims at deciphering some of the most urgent issues in this multidisciplinary field

Strongly-Coupled Quarks and Colorful Black Holes

We use the AdS/CFT correspondence to study the behavior of strongly-coupled quarks in a black hole background. The supergravity background consists of a six-dimensional Schwarzschild-black string AdS soliton, for which the bulk horizon extends from the AdS boundary down to an infra-red floor. By going to higher energy scales, the regime of validity of the classical supergravity background can be extended closer to the singularity than might be expected from the four-dimensional perspective. Small black holes potentially created by the Large Hadron Collider could typically carry color charges inherited from their parton progenitors. The dynamics of quarks near such a black hole depends on the curved spacetime geometry as well as the strong interaction with the color-charged black hole. We study the resulting behavior of quarks and compute the rate at which a quark rotating around the black hole loses energy. We also investigate how the interaction between a quark and an antiquark is altered by the presence of the black hole, which results in a screening length.Comment: Proceedings of the DPF-2011 Conference, 8 pages, 5 figures, added reference

Geochemical mapping of urban soils in Athens, Greece - Preliminary results

Η αστική γεωχημεία είναι ένας αναπτυσσόμενος επιστημονικός τομέας κυρίως λόγω των περιβαλλοντικών επιπτώσεων από την εξάπλωση των πόλεων και την αύξηση του αστικού πληθυσμού. Η παρούσα εργασία έχει ως στόχο τη γεωχημική χαρτογράφηση των επιφανειακών (0-10 cm) εδαφών της Αθήνας με έμφαση στη χωρική κατανομή δυνητικά βλαβερών χημικών στοιχείων. Η δειγματοληψία υπαίθρου πραγματοποιήθηκε βάσει τετραγωνικού κανάβου ισοδιάστασης 1 km και κάλυψε συνολική έκταση περίπου 200 km2, με προτεραιότητα σε παιδικές χαρές, σχολεία και πάρκα. Αναλύθηκαν320 εδαφικά δείγματα κοκκομετρίας < 100 μm με την τεχνική της φασματοσκοπίας ατομικής απορρόφησης μετά από διαλυτοποίηση με βασιλικό ύδωρ και προσδιορί- στηκαν τα στοιχεία Pb, Zn, Cu, Cd, Cr, Ni, Co και Mn. Οι μέσες συγκεντρώσεις των στοιχείων Pb (62 mg/kg), Cu (36 mg/kg), Zn (91 mg/kg) και Mn (465 mg/kg) είναι χαμηλότερες των αντίστοιχων συγκεντρώσεων άλλων Ευρωπαϊκών πόλεων ενώ οι συγκεντρώσεις των Cr (74 mg/kg), Ni (89 mg/kg) και Co (16 mg/kg) υψηλότερες. Το γεωχημικό ανάγλυφο αποτυπώθηκε σε περιβάλλον ΓΣΠ δίνοντας τη δυνατότητα προσδιορισμού διαφορετικών πηγών των στοιχείων. Τα αποτελέσματα της έρευνας συμβάλουν στην εκτίμηση της ποιότητας των εδαφών της Αθήνας και αποτελούν πολύτιμο εργαλείο στην αναγνώριση περιοχών περιβαλλοντικής επικινδυνότητας.Urban geochemistry is a fast growing scientific discipline mainly because of the profound impact of large cities on the environment as well as the increase in the world’s urban population. The present study aims to produce the urban geochemical map of Athens, based on multi-element analysis of surface soils (0-10 cm) with emphasis in the spatial distribution of potentially harmful elements (PHEs). Soil sampling was based on a regular 1km x 1km grid, laid over the survey area covering more than 200 km2. Sampling locations within the grid cells were selected giving priority to playgrounds, schools and urban parks. The < 100 μm fraction of a total of 320 soil samples were analysed by Flame Atomic Absorption Spectroscopy for Pb, Zn, Cu, Cd, Cr, Ni, Co and Mn after aqua regia dissolution. Average content of Pb (62 mg/kg), Cu (36 mg/kg), Zn (91 mg/kg) and Mn (465 mg/kg) in soil was lower than reported concentrations from other European cities while Cr (74 mg/kg), Ni (89 mg/kg) and Co (16 mg/kg) were relatively enriched. Geochemical maps were plotted within GIS enabling recognition of spatial trends in elemental concentrations and potential sources of the elements. The research outcome will contribute to the evaluation of quality characteristics of urban soils in Athens and drive attention to areas of any environmental or health risks

A template-based methodology for efficient microprocessor and FPGA accelerator co-design

Embedded applications usually require Software/Hardware (SW/HW) designs to meet the hard timing constraints and the required design flexibility. Exhaustive exploration for SW/HW designs is a very time consuming task, while the adhoc approaches and the use of partially automatic tools usually lead to less efficient designs. To support a more efficient codesign process for FPGA platforms we propose a systematic methodology to map an application to SW/HW platform with a custom HW accelerator and a microprocessor core. The methodology mapping steps are expressed through parametric templates for the SW/HW Communication Organization, the Foreground (FG) Memory Management and the Data Path (DP) Mapping. Several performance-area tradeoff design Pareto points are produced by instantiating the templates. A real-time bioimaging application is mapped on a FPGA to evaluate the gains of our approach, i.e. 44,8% on performance compared with pure SW designs and 58% on area compared with pure HW designs

Anterior teeth root inclination prediction derived from digital models : a comparative study of plaster study casts and CBCT images

To assess the accuracy of digital models generated using commercially available software to predict anterior teeth root inclination characteristics and compare the results to relevant data obtained from CBCT images. Following sample size calculation and after application of inclusion and exclusion criteria, pre-treatment maxillary and mandibular plaster models and the corresponding CBCT scans of 31 patients attending a private orthodontic clinic were selected. The subjects were 10 males and 21 females with age range 12 to 40 years. Plaster models were scanned using the high resolution mode of an Ortho Insight 3D scanner and CBCT scans were taken using a Kodak 9500 Cone Beam 3D System machine. The teeth on the digital scans were segmented and virtual roots were predicted and constructed by the Ortho Insight 3D software. The long axes of the predicted roots and the actual roots, as segmented from the CBCT images, were computed using best-fit lines. The inter-axis angle was used to assess error in root inclination prediction by the software. Mann-Whitney and Kruskal-Wallis tests were used. Intra-examiner error was evaluated using the Bland-Altman method. The maximum disparity in angle between images derived from digital models and CBCT data was almost 40 degrees (upper left canine). The upper and lower canines produced the worst results, followed by the lower lateral incisors. The upper central incisors showed the best results, although the maximum angle of difference exceeded 20 degrees (with the median around 8 degrees). Root morphology imaging prediction is not a primary function of this software and this study confirmed its limitation as a sole tool in routine clinical applications. At present these predictions cannot be considered accurate or reliable unless correlated clinically with a radiographic image

Area-throughput trade-offs for SHA-1 and SHA-256 hash functions’ pipelined designs

High-throughput designs of hash functions are strongly demanded due to the need for security in every transmitted packet of worldwide e-transactions. Thus, optimized and non-optimized pipelined architectures have been proposed raising, however, important questions. Which is the optimum number of the pipeline stages? Is it worth to develop optimized designs or could the same results be achieved by increasing only the pipeline stages of the non-optimized designs? The paper answers the above questions studying extensively many pipelined architectures of SHA-1 and SHA-256 hashes, implemented in FPGAs, in terms of throughput/area (T/A) factor. Also, guides for developing efficient security schemes designs are provided. Read More: https://www.worldscientific.com/doi/abs/10.1142/S021812661650032

The Unmet Orthodontic Treatment Need of Adolescents and Influencing Factors for not Seeking Orthodontic Therapy

The purpose of this study was to estimate unmet orthodontic treatment needs of adolescents in Zagreb, Croatia, compare normative and self-perceived need and investigate factors influencing the reason why untreated subjects with severe malocclusions have not been treated before. One thousand and forty-two non-orthodontically treated subjects in age groups of 12 and 18 years, from sixteen randomly selected public schools in Zagreb, Croatia were examined. The Dental Aesthetic Index, Aesthetic Component of Index of Orthodontic Treatment Need and a questionnaire concerning self-perceived orthodontic treatment need, perception of aesthetics, function, behaviors and socioeconomic status were used. Around one third of untreated adolescent population had an objective need, less than 20 percent had aesthetic need, and self-perceived need was reported in one third of population. Associations and agreements between objective, aesthetic and self-perceived need were weak (r=0.27–0.48; p0.05) to 0.32 (p<0.05), respectively). Satisfaction with personal dental appearance and awareness of malocclusion were better related in persons with no treatment need or minor need (r=0.53–0.59) than in those with major need (r=0.31–0.40). Multiple logistic regression analyses confirmed that objective, aesthetic and self-perceived needs were better related between themselves than to socioeconomic status of subjects, function, activities of daily living and oral health-related behaviors. It appears that self-perceived treatment need has low role in predicting objective need, but relation between satisfaction and awareness of malocclusion could be one of basic factors in process of making decision to go for treatment and maybe could serve in predicting patient’s compliance