This paper is aimed at calibrating the relative posture and position, i.e. extrinsic parameters, of a stationary camera against a 3D reference object which is not directly visible from the camera. We capture the reference object via a mirror under three different unknown poses, and then calibrate the extrinsic parameters from 2D appearances of reflections of the reference object in the mirrors.The key contribution of this paper is to present a new algorithm which returns a unique solution of three P3P problems from three mirrored images. While each P3P problem has up to four solutions and therefore a set of three P3P problems has up to 64 solutions, our method can select a solution based on an orthogonality constraint which should be satisfied by all families of reflections of a single reference object. In addition we propose a new scheme to compute the extrinsic parameters by solving a large system of linear equations. These two points enable us to provide a unique and robust solution.We demonstrate the advantages of the proposed method against a state-of-the-art by qualitative and quantitative evaluations using synthesized and real data.
The dental follicle is an ectomesenchymal tissue that surrounds developing tooth germ and that contains osteoblastic-lineage-committed stem/progenitor cells. We examined the osteogenic potential of human dental follicle cells (hDFC) by microarray analysis. We first compared the characteristics of hDFC with those of human bone marrow mesenchymal stem cells (hMSC). Like hMSC, hDFC expressed stem cell markers such as STRO-1 and Notch-1 and differentiated not only into the osteoblastic lineage, but also into the adipogenic lineage. We analyzed the gene expression profiles of hDFC and hMSC that were not differentiated toward the osteogenic lineage. The expression of cell markers and growth factor receptors by hDFC and hMSC was similar, whereas the expression pattern of homeobox genes differed between hDFC and hMSC. Next, we investigated gene expression in hDFC during osteogenic differentiation. Gene expression profiles were analyzed in hDFC cultured in osteogenic induction medium (OIM) or in growth medium (GM) for 3 and 10 days. Many genes whose expression was regulated under these conditions were functionally categorized as "transcription" genes. Osteogenic markers were up-regulated in hDFC during osteogenic differentiation, whereas neurogenic markers were down-regulated. The genes whose expression was regulated in hDFC during osteogenic differentiation were further analyzed by ingenuity pathway analysis and real-time polymerase chain reaction. Bone morphogenetic protein and transforming growth factor-β signaling pathways were activated in hDFC cultured in OIM for 3 days. This study indicates that the dental follicle contains stem cells and/or osteoblastic progenitor cells and is a potential cellular resource for bone regeneration therapy.
Continuous and repeated geomagnetic observations have been performed at 8 stations in the eastern part of Hokkaido, NE Japan, to confirm a detailed picture of geomagnetic secular changes. The observation delineated anomalously large secular changes of about 1 nT/year that have lasted at least for about 3 to 30 years (depending on the period of observations) at 3 stations situated in the remarkable geomagnetic anomaly region. Contributions from the earth's core or ionospheric origin are ruled out as source mechanisms because of the local distribution of the anomalous stations. Heat-triggered volcanomagnetic effect cannot be the origin of such secular changes because the stations are quite far from the volcanoes. Instead, we propose the changes originate from stressinduced tectonomagnetic effect (piezomagnetism). We performed piezomagnetic modeling under the condition that observed regional tectonic stress has been applied to the highly magnetized rock bodies inferred from the analysis of the observed geomagnetic anomalies. The modeling explained well the secular changes by assuming the stress sensitivity of the order of 10 −2 MPa −1 , which is one order larger than the ordinarily used value.
Background/purpose
Plasma rich in growth factors (PRGFs), which is prepared from autologous blood from patients, has been reported with regards to bone regeneration for dental implants. Human dental follicle cells (hDFCs) have the capacity to commit to multiple cell types such as the osteoblastic lineage. The aim of this study is to evaluate the effects of PRGFs for mineralization in hDFCs.
Materials and methods
PRGFs was prepared from whole blood centrifuged at 460
g
for 8 minutes. hDFCs isolated from the dental follicle with collagenase/dispase were cultured with growth medium or osteogenic induction medium (OIM) containing PRGFs or fetal bovine serum. Concentrations of the growth factors were examined using an enzyme-linked immunosorbent assay kit. A cell migration assay was used for two-dimensional movement. Gene expressions were examined with real-time polymerase chain reaction using a DyNAmo SYBR Green quantitative polymerase chain reaction kit.
Results
The platelet concentration in PRGF Fraction 2 was 2.14-fold higher than in whole blood. White blood cells were not detected in PRGFs. Transforming growth factor-β levels were higher than insulin-like growth factor-1, platelet-derived growth factor-AB and -BB, and vascular endothelial growth factors in PRGF Fraction 2. Proliferation and migration by hDFCs increased in OIM supplemented with PRGFs in a dose-dependent manner and were higher in hDFCs cultured in OIM plus 10% PRGFs compared with OIM plus 10% fetal bovine serum. PRGFs upregulated the gene expression of
type I collagen
,
osteomodulin
,
alkaline phosphatase
,
bone morphogenic protein-4
, and
transforming growth factor-β
in hDFCs.
Conclusion
PRGFs may promote bone regeneration due to it including high levels of growth factors.
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