Bench-Scale Investigation of Limestone Size Evolution in a Fluidized Bed Combustor

The influence of temperature, heating rate and chemical reaction on fragmentation and attrition of limestone in a fluidized bed (FB) was investigated. The intensity of fragmentation and attrition was measured in the same apparatus but at different fluidizing velocities and fluidizing media. It was found that the heating rate has a positive effect on fragmentation for the tested limestones. The effect of bed temperature on limestone fragmentation was inconclusive. The influence of chemical reaction on the fragmentation seems to be complicated; CO2 release due to calcination would prompt fragmentation while the sulfation would increase the gas diffusion resistance and depresses the fragmentation intensity. On the other hand, the CaSO3/CaSO4 layer was found to be attrition-resistant leading to small attrition rates. Attrition rate constant showed to decay exponentially with time and approaching a constant for all limestone particles. Particle sizes between 200-400 µm have larger attrition rate constant than coarse ones perhaps due to their large specific surface area

Self-organising comprehensive handover strategy for multi-tier LTE-advanced heterogeneous networks

Long term evolution (LTE)-advanced was introduced as real fourth generation (4G) with its new features and additional functions, satisfying the growing demands of quality and network coverage for the network operators' subscribers. The term muti-tier has also been recently used with respect to the heterogeneity of the network by applying the various subnetwork cooperative systems and functionalities with self-organising capabilities. Using indoor short-range low-power cellular base stations, for example, femtocells, in cooperation with existing long-range macrocells are considered as the key technical challenge of this multi-tier configuration. Furthermore, shortage of network spectrum is a major concern for network operators which forces them to spend additional attentions to overcome the degradation in performance and quality of services in 4G HetNets. This study investigates handover between the different layers of a heterogeneous LTE-advanced system, as a critical attribute to plan the best way of interactive coordination within the network for the proposed HetNet. The proposed comprehensive handover algorithm takes multiple factors in both handover sensing and decision stages, based on signal power reception, resource availability and handover optimisation, as well as prioritisation among macro and femto stations, to obtain maximum signal quality while avoiding unnecessary handovers

Dental Students’ Perceptions of and Experiences with Prosthodontics: Ten Graduating Classes at One Institution

It is important for members of the dental specialties to understand what motivates students to enter the specialty in order to ensure its continuing development and ability to meet patient needs. The aim of this study was to compare ten graduating classes at Harvard School of Dental Medicine (HSDM) regarding students' experiences with and perceptions of prosthodontics and factors influencing those interested in pursuing prosthodontics as a specialty. In 2013, HSDM students in the classes of 2012-16 were surveyed, achieving a response rate of 81%. Survey questions sought information regarding specialty choice, factors influencing the choice, student experiences with prosthodontics, and student perceptions of the dental disciplines. Responses were compared to those from a prior study of the HSDM classes of 2007-11. The responses showed a decrease in negative student experiences with prosthodontics. The students regarded prosthodontics highly for its impact on patient quality of life; however, students interested in pursuing prosthodontics as a specialty decreased. All students said provider enjoyment was most important in choice of specialty. Cost of program, patient type, and program location were factors that especially influenced students interested in prosthodontics. The improved student experiences with and perspectives on prosthodontics may be a result of a curriculum change that led to more prosthodontics procedures and case completions by students. The fall in students interested in prosthodontics may have resulted from prosthodontic faculty transitions that occurred when the survey was conducted, as well as large debt burdens in spite of the fact that prosthodontists' earnings are among the highest in dentistry. Faculty must educate and mentor students about the realities of the profession, provide positive learning experiences in the field, and encourage students who enjoy prosthodontics to pursue specialty training

Factors Influencing Dental Students’ Specialty Choice: A Survey of Ten Graduating Classes at One Institution

The aim of this study was to survey ten graduating classes at Harvard School of Dental Medicine regarding students' specialty choice and factors influencing that choice. Students were surveyed once in 2008 (for the Classes of 2007-11) and again in 2013 (for the Classes of 2012-16). A prior article reported results regarding students' interest in and experiences with prosthodontics; this article presents results regarding their interest in all dental specialties and factors influencing those interests. Of a total 176 students in the Classes of 2012-16, 143 responded to the survey, for a response rate of 81%, compared to a 95% response rate (167 of total 176 students) for the Classes of 2007-11. The results showed that orthodontics was the most popular specialty choice, followed by oral and maxillofacial surgery. From the 2008 to the 2013 survey groups, there was an increase in the percentages of students planning to pursue oral and maxillofacial surgery, pediatric dentistry, and postdoctoral general dentistry. The educational debt these students expected to accrue by graduation also increased. The largest percentage of students chose "enjoyment of providing the specialty service" as the factor most influencing their specialty choice. "Prior dental school experience" and "faculty influence" were greater influences for students pursuing specialties than those pursuing postdoctoral general dentistry. Increased interest in particular disciplines may be driven by high debt burdens students face upon graduation. Factors related to mentoring especially influenced students pursuing specialties, demonstrating the importance of student experiences outside direct patient care for exposure to the work of specialists beyond the scope of predoctoral training. This finding suggests that dental schools should increase mentoring efforts to help students make career decisions based not on financial burden but rather on personal interest in the specialty, which is likely to have a more satisfying result for them in the long run

Immunohistochemical detection of scrapie prion proteins in clinically normal sheep in Pennsylvania

Following diagnosis of scrapie in a clinically suspect Suffolk sheep, 7 clinically normal flockmates were purchased by the Pennsylvania Department of Agriculture to determine their scrapie status using an immunohistochemical procedure. Two of the 7 euthanized healthy sheep had positive immunohistochemical staining of the prion protein of scrapie (PrP-Sc) in their brains, nictitating membranes, and tonsils. The PrP-Sc was localized in the areas of the brain where, histopathologically, there was neurodegeneration and astrocytosis. The PrP-Sc occurred within germinal centers of the affected nictitating membranes and tonsils and was located in the cytoplasm of the dendrite-like cells, lymphoid cells, and macrophages. These results confirm that immunohistochemical examination of the nictitating membrane can be used as a screen for the presence of scrapie infection in clinically normal sheep at a capable veterinary diagnostic laboratory. In sheep with a PrP-Sc–positive nictitating membrane, the diagnosis of scrapie should be confirmed by histopathology and immunohistochemical examination of the brain following necropsy. Following full validation, immunohistochemistry assays for detection of PrP-Sc in nictitating membrane lymphoid tissues can improve the effectiveness of the scrapie control and eradication program by allowing diagnosis of the disease in sheep before the appearance of clinical signs

Inflammation induced by bacterial cell wall fragments in the rat air pouch. Comparison of rat strains and measurement of arachidonic acid metabolites.

Streptococcal cell wall fragments, suspended in phosphate-buffered saline, were injected into a preformed subcutaneous air pouch in rats. The advantage of the air pouch model is the capacity for quantitation of exudative, cellular, and proliferative responses and soluble mediators. Accumulation of pouch fluid containing many leukocytes occurred during the first 3 days. Granulation tissue separable from the surrounding subcutaneous tissue developed by 6 days. Immunofluorescence and immunoperoxidase staining showed the presence of cell walls in inflammatory cells both in pouch fluid and in pouch tissue. Histologic features of this inflammation included an acute exudative phase with a predominantly neutrophil infiltration followed by a chronic phase characterized by fibroblast proliferation, formation of blood vessels, and infiltration with mononuclear cells. The lining of the pouch before injection of cell wall developed morphologic features of synovial membrane, which became more evident during the chronic phase of induced inflammation. Outbred Sprague-Dawley and inbred Lewis rats developed more pouch fluid, cell numbers in the pouch fluid, and granulation tissue than inbred Buffalo rats. The arachidonic acid metabolites, prostaglandin E2 and leukotriene B4, were measured in the pouch fluid, and more of each was produced in the Lewis than in the Buffalo strain. These measurements of inflammation are consistent with the relative susceptibility of these strains to cell-wall-induced arthritis. This model of inflammation can be used in the examination of the regulatory mechanisms of evolving chronic inflammation

Role of disclinations in determining the morphology of deformable fluid interfaces

We study the equilibrium shapes of vesicles, with an in-plane nematic order, using a Monte-Carlo scheme and show that highly curved shapes, like tubes and discs, with a striking similarity to the structures engendered by certain curvature sensing peripheral membrane proteins, can be spontaneously generated by anisotropic directional curvature with nematic disclinations playing and important role. We show that the coupling between nematic order and local curvature could lead to like defects moving towards each other and unlike defects moving away, in turn leading to tube formation. Thermally induced defect pair production lead to branched tubular structures. It is also shown that helical arrangement of the membrane tubes, with nematic field spiraling around it, is a dominant soft mode of the system.Comment: 6 Figures; Soft Matter, Advance Article 201

Assembly and Interrogation of Alzheimer’s Disease Genetic Networks Reveal Novel Regulators of Progression

Alzheimer’s disease (AD) is a complex multifactorial disorder with poorly characterized pathogenesis. Our understanding of this disease would thus benefit from an approach that addresses this complexity by elucidating the regulatory networks that are dysregulated in the neural compartment of AD patients, across distinct brain regions. Here, we use a Systems Biology (SB) approach, which has been highly successful in the dissection of cancer related phenotypes, to reverse engineer the transcriptional regulation layer of human neuronal cells and interrogate it to infer candidate Master Regulators (MRs) responsible for disease progression. Analysis of gene expression profiles from laser-captured neurons from AD and controls subjects, using the Algorithm for the Reconstruction of Accurate Cellular Networks (ARACNe), yielded an interactome consisting of 488,353 transcription-factor/ target interactions. Interrogation of this interactome, using the Master Regulator INference algorithm (MARINa), identified an unbiased set of candidate MRs causally responsible for regulating the transcriptional signature of AD progression. Experimental assays in autopsyderived human brain tissue showed that three of the top candidate MRs (YY1, p300 and ZMYM3) are indeed biochemically and histopathologically dysregulated in AD brains compared to controls. Our results additionally implicate p53 and loss of acetylation homeostasis in the neurodegenerative process. This study suggests that an integrative, SB approach can be applied to AD and other neurodegenerative diseases, and provide significant novel insight on the disease progression