A comparison of structured and unstructured navigation through a CBT package

The advent of hypertext has opened up new possibilities in computer-based training. The design of courseware without any predetermined structure could make the designer's task easier, and allow greater flexibility for the trainee to structure the learning environment to suit their own learning style, This investigation was concerned with the exploration of performance differences in structured and unstructured training environments. In the structured condition, subjects encountered presequenced training and practice modules. For the unstructured condition, subjects determined their own sequence of modules. It was proposed that performance may be better in the unstructured condition. The findings indicate that this depends upon individual differences in cognitive style, some styles seemingly better at exploiting the unstructured learning environment than others

The prevalence of second canals in the mesiobuccal root of maxillary molars in a South African subpopulation : a cone beam computed tomography study

Introduction: Endodontic therapy is a global routine dental therapeutic procedure. Despite recent and present advances in dentistry and particularly with the popularity of implant dentistry, it remains biologically and aesthetically advantageous for retention of one�s original dentition. Tooth extraction followed by surgical placement of dental implants should remain a last resort in management. Treatment success depends on intricate knowledge and a thorough understanding of the anatomy of the root canal system, in order to adequately debride, disinfect, and obturate teeth affected by irreversible pulpitis or pulp necrosis. High endodontic failure rates are frequent in the maxillary molar tooth owing to the complexity of their root canal anatomy, and variations in the number of mesiobuccal (MB) roots. Conventional radiographic imaging techniques are unreliable for the detection of multiple canals, whereas cone beam computed tomography (CBCT) has proven to be effective for visualization of additional canals of root canal systems. There is little published data on the prevalence of second canals in the MB roots (MB2) of permanent maxillary first and second molars in a South African subpopulation. The aim of this study is to detect the prevalence of MB2 canals by analysing axial views of CBCT scans of adult patients. Methodology: A total number of 200 patient CBCT scans, from 100 male and 100 female patients respectively, were enrolled in the study. A total of 800 teeth were analysed in-vivo on CBCT scans, comprising 200 right maxillary first molar teeth (tooth 16), 200 left maxillary first molar teeth (tooth 26), 200 right maxillary second molar teeth (tooth 17), and 200 left maxillary second molar teeth (tooth 27). Teeth displaying radiological evidence of an additional mesiobuccal canal (MB2) were identified. Results: First maxillary molar teeth showed a high prevalence of MB2 canals, 92% and 87%, for the 16 and 26 respectively. Second maxillary molar teeth showed a lower, but still significant, prevalence of MB2 canals, 69% and 65%, for the 17 and 27 respectively. An association between patient age, gender and the prevalence of MB2 canals was not noted in the study sample. Conclusion: Root morphology and anatomy of permanent maxillary first and second molar teeth is highly variable. The prevalence of additional canals in the MB roots is a frequent finding which has previously been underreported. The presence of these variations significantly impact endodontic therapy success, longevity, and retention of the natural dentition. The prevalence of these canals requires documentation for dissemination of this knowledge and greater cognizance thereof with respect to more accurate endodontic outcomes and success.Mini Dissertation (MChD)--University of Pretoria, 2018.ProsthodonticsMChDUnrestricte

Mechanism of Fluoride Uptake by Hydroxyapatite from Acidic Fluoride Solutions: I. Theoretical Considerations

A mathematical model for the mechanism of calcium fluoride formation on hydroxyapatite in buffered fluoride solutions is proposed. It takes into account the physical and chemical processes that occur during the reaction. With the model it is possible to evaluate a priori the fluoride uptake potential of fluoride solutions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67263/2/10.1177_00220345700490066601.pd

Numerical comparison of two approaches for the study of phase transitions in small systems

We compare two recently proposed methods for the characterization of phase transitions in small systems. The validity and usefulness of these approaches are studied for the case of the q=4 and q=5 Potts model, i.e. systems where a thermodynamic limit and exact results exist. Guided by this analysis we discuss then the helix-coil transition in polyalanine, an example of structural transitions in biological molecules.Comment: 16 pages and 7 figure

ADAMTS9-regulated pericellular matrix dynamics governs focal adhesion-dependent smooth muscle differentiation

Focal adhesions anchor cells to extracellular matrix (ECM) and direct assembly of a pre-stressed actin cytoskeleton. They act as a cellular sensor and regulator, linking ECM to the nucleus. Here, we identify proteolytic turnover of the anti-adhesive proteoglycan versican as a requirement for maintenance of smooth muscle cell (SMC) focal adhesions. Using conditional deletion in mice, we show that ADAMTS9, a secreted metalloprotease, is required for myometrial activation during late gestation and for parturition. Through knockdown of ADAMTS9 in uterine SMC, and manipulation of pericellular versican via knockdown or proteolysis, we demonstrate that regulated pericellular matrix dynamics is essential for focal adhesion maintenance. By influencing focal adhesion formation, pericellular versican acts upstream of cytoskeletal assembly and SMC differentiation. Thus, pericellular versican proteolysis by ADAMTS9 balances pro- and anti-adhesive forces to maintain an SMC phenotype, providing a concrete example of the dynamic reciprocity of cells and their ECM

The longevity of restorations - a literature review

Dentists need to consider various factors when choosing restorative materials, with the longevity of restorations being one of the most important criteria. Replacement of failed restorations constitutes over 60% of operative procedures, leading to high annual costs. This literature review compares the survival rates of different restorative materials used for both direct and indirect restorations. A literature search was carried out using Pubmed to identify all articles on restorative materials published from 1974 to 2014, of which 22 were included in this review. For direct restorations, amalgam showed the highest survival rates (22.5 years), with an average survival rate of 95% over 10 years, followed by composite resins (90% over 10 years), and glass ionomer cements (65% over 5 years). For indirect restorations, gold restorations are still the “gold standard” with a 96% over 10 years survival rate, followed by porcelain-fused-to-metal crowns (PFM) (90% over 10 years), and all ceramic crowns (75-80% over 10 years). Amongst the ceramic restorations, eMax shows the longest survival rate (90% over 10 years), and Zirconia the lowest (88% over five years). The longevity of restorations depends on many factors, including: materials used, type of restorative procedure, patient parameters, operator variables, and local factors.https://www.sada.co.za/the-sadjam201

From Social Data Mining to Forecasting Socio-Economic Crisis

Socio-economic data mining has a great potential in terms of gaining a better understanding of problems that our economy and society are facing, such as financial instability, shortages of resources, or conflicts. Without large-scale data mining, progress in these areas seems hard or impossible. Therefore, a suitable, distributed data mining infrastructure and research centers should be built in Europe. It also appears appropriate to build a network of Crisis Observatories. They can be imagined as laboratories devoted to the gathering and processing of enormous volumes of data on both natural systems such as the Earth and its ecosystem, as well as on human techno-socio-economic systems, so as to gain early warnings of impending events. Reality mining provides the chance to adapt more quickly and more accurately to changing situations. Further opportunities arise by individually customized services, which however should be provided in a privacy-respecting way. This requires the development of novel ICT (such as a self- organizing Web), but most likely new legal regulations and suitable institutions as well. As long as such regulations are lacking on a world-wide scale, it is in the public interest that scientists explore what can be done with the huge data available. Big data do have the potential to change or even threaten democratic societies. The same applies to sudden and large-scale failures of ICT systems. Therefore, dealing with data must be done with a large degree of responsibility and care. Self-interests of individuals, companies or institutions have limits, where the public interest is affected, and public interest is not a sufficient justification to violate human rights of individuals. Privacy is a high good, as confidentiality is, and damaging it would have serious side effects for society.Comment: 65 pages, 1 figure, Visioneer White Paper, see http://www.visioneer.ethz.c

Immediate implant placement and provisionalization following tumor-resective surgery in the midfacial region : a case series

Surgical and prosthodontic restoration of the midfacial region following tumor resection has always posed a considerable challenge, as this area serves crucial functional and esthetic roles. Being diagnosed and subsequently treated for facial tumors can have an immense psychosocial impact on a patient, as the resulting defects are often disfiguring, and lead to an inability to masticate, swallow, and speak clearly. Provision of an immediate facial and dental prosthesis at the time of surgery can limit these side effects and help reduce mental duress on these patients and their families, as well as aid in the process of rehabilitation. Rapid prototyping (RP) and 3D printing, as this paper shows, assists presurgical planning of the tumor resection, as well as the manufacture of maxillofacial and dental prostheses. Often these defects are extensive, so prosthesis retention is aided by zygomatic implants placed at the time of surgical resection. When placed at this time, and prior to radiation therapy, these craniofacial implants have improved survival rates. Thus, this treatment modality can improve postoperative recovery considerably, while at the same time allowing for cleaning and monitoring of the resected site for tumor recurrence.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1532-849X2019-06-01hj2017Prosthodontic

Comparison of alveolar osteitis with post implant removal osteitis (can a “dry socket” occur after implant removal?)

The introduction of dental implants spawned an exponential growth in the number of fixtures being placed to meet the increasing functional and aesthetic demands of patients. In response, manufacturers have flooded the market with new, cheaper systems, and many general practitioners have begun placing implants to support restorations. Enhanced life expectancy means that implants placed in younger people are expected to function effectively over many years. Studies have shown that a certain low percentage of implants will develop early or late complications,1 and that the risks are greater with increased usage.2 It is thus anticipated that practitioners will be faced with increasing numbers of implant-related complications that will require appropriate management, or even implant removal.1 Hence the majority of complications will be in older persons where healing may be compromised due to physiological ageing, systemic medication, or other age-related factors.https://www.sada.co.za/the-sadjam2018Prosthodontic

New primers for promising single-copy genes in fungal phylogenetics and systematics

Developing powerful phylogenetic markers is a key concern in fungal phylogenetics. Here we report degenerate primers that amplify the single-copy genes Mcm7 (MS456) and Tsr1 (MS277) across a wide range of Pezizomycotina (Ascomycota). Phylogenetic analyses of 59 taxa belonging to the Eurotiomycetes, Lecanoromycetes, Leotiomycetes, Lichinomycetes and Sordariomycetes, indicate the utility of these loci for fungal phylogenetics at taxonomic levels ranging from genus to class. We also tested the new primers in silico using sequences of Saccharomycotina, Taphrinomycotina and Basidiomycota to predict their potential of amplifying widely across the Fungi. The analyses suggest that the new primers will need no, or only minor sequence modifications to amplify Saccharomycotina, Taphrinomycotina and Basidiomycota