1,133 research outputs found
Twenty-five years of recombinant human growth factors rhPDGF-BB and rhBMP-2 in oral hard and soft tissue regeneration.
Contemporary oral tissue engineering strategies involve recombinant human growth factor approaches to stimulate diverse cellular processes including cell differentiation, migration, recruitment, and proliferation at grafted areas. Recombinant human growth factor applications in oral hard and soft tissue regeneration have been progressively researched over the last 25âyears. Growth factor-mediated surgical approaches aim to accelerate healing, tissue reconstruction, and patient recovery. Thus, regenerative approaches involving growth factors such as recombinant human platelet-derived growth factor-BB (rhPDGF-BB) and recombinant human bone morphogenetic proteins (rhBMPs) have shown certain advantages over invasive traditional surgical approaches in severe hard and soft tissue defects. Several clinical studies assessed the outcomes of rhBMP-2 in diverse clinical applications for implant site development and bone augmentation. Current evidence regarding the clinical benefits of rhBMP-2 compared to conventional therapies is inconclusive. Nevertheless, it seems that rhBMP-2 can promote faster wound healing processes and enhance de novo bone formation, which may be particularly favorable in patients with compromised bone healing capacity or limited donor sites. rhPDGF-BB has been extensively applied for periodontal regenerative procedures and for the treatment of gingival recessions, showing consistent and positive outcomes. Nevertheless, current evidence regarding its benefits at implant and edentulous sites is limited. The present review explores and depicts the current applications, outcomes, and evidence-based clinical recommendations of rhPDGF-BB and rhBMPs for oral tissue regeneration
Asymptotics and local constancy of characters of p-adic groups
In this paper we study quantitative aspects of trace characters
of reductive -adic groups when the representation varies. Our approach
is based on the local constancy of characters and we survey some other related
results. We formulate a conjecture on the behavior of relative to
the formal degree of , which we are able to prove in the case where
is a tame supercuspidal. The proof builds on J.-K.~Yu's construction and the
structure of Moy-Prasad subgroups.Comment: Proceedings of Simons symposium on the trace formul
Shaping the research experiences of graduate students using action research
s u m m a r y a r t i c l e i n f o Background: Nursing research capacity is often not optimal in developing countries. Capacity building at the graduate nurse level presents an opportunity for improved research output. Students pursuing a research methods course at a nursing school in Jamaica expressed fear and anxiety towards the course. Action research was used to address this fear and improve learning outcomes. Objective: To determine attitudes towards research and to improve the experience of graduate students pursuing a research methods course at a nursing school in Jamaica. Methods: Students (n = 44) registered in the Research Methods course of the MScN at a nursing school in Kingston, Jamaica for the academic year 2010/2011, were invited to participate. Each student was assigned a main supervisor and an alternate supervisor and all had equal access to the course leader and content. On completion of the course three focus group discussions of 10-14 students per group were conducted to determine how students felt about the course experience and their attitude towards the course. Results: Thirty-seven students (mean age of 41.4 ± 1.5 years; 94% female) participated in the exploratory course evaluation exercise. The participants reported that they entered research methods with feelings of apprehension and anxiety. However, these fears were allayed by a combination of factors including interest in students' welfare, affirmation of students, respect for and understanding of students' needs and resourcefulness, and the use of a panel of experts. Barriers included faculty's unrealistic expectations of students' research competencies and the limited time in which to learn and apply concepts. While students thought the course as challenging they felt more confident that they could be successful on completion of the course. Conclusion: Significant improvement in attitudes to research was realized among graduate nursing students using action research at an urban school of nursing in Jamaica
PlateletâDerived Growth Factor Stimulates Bone Fill and Rate of Attachment Level Gain: Results of a Large Multicenter Randomized Controlled Trial
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141430/1/jper2205.pd
PlateletâDerived Growth Factor Promotes Periodontal Regeneration in Localized Osseous Defects: 36âMonth Extension Results From a Randomized, Controlled, DoubleâMasked Clinical Trial
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141092/1/jper0456.pd
Strong "quantum" chaos in the global ballooning mode spectrum of three-dimensional plasmas
The spectrum of ideal magnetohydrodynamic (MHD) pressure-driven (ballooning)
modes in strongly nonaxisymmetric toroidal systems is difficult to analyze
numerically owing to the singular nature of ideal MHD caused by lack of an
inherent scale length. In this paper, ideal MHD is regularized by using a
-space cutoff, making the ray tracing for the WKB ballooning formalism a
chaotic Hamiltonian billiard problem. The minimum width of the toroidal Fourier
spectrum needed for resolving toroidally localized ballooning modes with a
global eigenvalue code is estimated from the Weyl formula. This
phase-space-volume estimation method is applied to two stellarator cases.Comment: 4 pages typeset, including 2 figures. Paper accepted for publication
in Phys. Rev. Letter
Validation in Fusion Research: Towards Guidelines and Best Practices
Because experiment/model comparisons in magnetic confinement fusion have not
yet satisfied the requirements for validation as understood broadly, a set of
approaches to validating mathematical models and numerical algorithms are
recommended as good practices. Previously identified procedures, such as
verification, qualification, and analysis of error and uncertainty, remain
important. However, particular challenges intrinsic to fusion plasmas and
physical measurement therein lead to identification of new or less familiar
concepts that are also critical in validation. These include the primacy
hierarchy, which tracks the integration of measurable quantities, and
sensitivity analysis, which assesses how model output is apportioned to
different sources of variation. The use of validation metrics for individual
measurements is extended to multiple measurements, with provisions for the
primacy hierarchy and sensitivity. This composite validation metric is
essential for quantitatively evaluating comparisons with experiments. To mount
successful and credible validation in magnetic fusion, a new culture of
validation is envisaged.Comment: 27 pages, 1 table, 6 figure
Effects of hydroxyapatite and PDGF concentrations on osteoblast growth in a nanohydroxyapatite-polylactic acid composite for guided tissue regeneration
The technique of guided tissue regeneration (GTR) has evolved over recent years in an attempt to achieve periodontal tissue regeneration by the use of a barrier membrane. However, there are significant limitations in the currently available membranes and overall outcomes may be limited. A degradable composite material was investigated as a potential GTR membrane material. Polylactic acid (PLA) and nanohydroxyapatite (nHA) composite was analysed, its bioactive potential and suitability as a carrier system for growth factors were assessed. The effect of nHA concentrations and the addition of platelet derived growth factor (PDGF) on osteoblast proliferation and differentiation was investigated. The bioactivity was dependent on the nHA concentration in the films, with more apatite deposited on films containing higher nHA content. Osteoblasts proliferated well on samples containing low nHA content and differentiated on films with higher nHA content. The composite films were able to deliver PDGF and cell proliferation increased on samples that were pre absorbed with the growth factor. nHAâPLA composite films are able to deliver active PDGF. In addition the bioactivity and cell differentiation was higher on films containing more nHA. The use of a nHAâPLA composite material containing a high concentration of nHA may be a useful material for GTR membrane as it will not only act as a barrier, but may also be able to enhance bone regeneration by delivery of biologically active molecules
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Recent Developments in Geothermal Drilling Fluids
In the past, standard drilling muds have been used to drill most geothermal wells. However, the harsh thermal and chemical environment and the unique geothermal formations have led to such problems as excessive thickening of the fluid, formation damage, and lost circulation. This paper describes three recent development efforts aimed at solving some of these drilling fluid problems. Each of the efforts is at a different stage of development. The Sandia aqueous foam studies are still in the laboratory phase, NL Baroid's polymeric deflocculant is soon to be field tested, and the Mudtech high-temperature mud was field tested several months ago. Low density and the capability to suspend particles at low relative velocities are two factors which make foam an attractive drilling fluid. The stability of these foams and their material properties at high temperatures are presently unknown and this lack of information has precluded their use as a geothermal drilling fluid. The aqueous foam studies being conducted at Sandia are aimed at screening available surfactants for temperature and chemical stability. Approximately 100 surfactants have been tested at temperatures of 260 and 310 C (500 and 590 F), and several of these candidates appear very promising. NL Baroid has developed a polymeric deflocculant for water-based muds which shows promise in retarding thermal degradation effects and associated gelation. Formulations containing this new polymer have shown good rheological properties up to 260 C (500 F) in laboratory testing. A high-temperature mud consisting primarily of sepiolite, bentonite, and brown coal has been developed by Mudtech, Inc. A field test of this mud was conducted in a geothermal well in the Imperial Valley of California in May 1980. The fluid exhibited good hole-cleaning characteristics and good rheological properties throughout the test
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