1,796 research outputs found

    Characterization of the Millimeter-Wave Polarization of Centaurus A with QUaD

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    Centaurus (Cen) A represents one of the best candidates for an isolated, compact, highly polarized source that is bright at typical cosmic microwave background (CMB) experiment frequencies. We present measurements of the 4 degree by 2 degree region centered on Cen A with QUaD, a CMB polarimeter whose absolute polarization angle is known to 0.5 degrees. Simulations are performed to assess the effect of misestimation of the instrumental parameters on the final measurement and systematic errors due to the field's background structure and temporal variability from Cen A's nuclear region are determined. The total (Q, U) of the inner lobe region is (1.00 +/- 0.07 (stat.) +/- 0.04 (sys.), -1.72 +/- 0.06 +/- 0.05) Jy at 100 GHz and (0.80 +/- 0.06 +/- 0.06, -1.40 +/- 0.07 +/- 0.08) Jy at 150 GHz, leading to polarization angles and total errors of -30.0 +/- 1.1 degrees and -29.1 +/- 1.7 degrees. These measurements will allow the use of Cen A as a polarized calibration source for future millimeter experiments.Comment: 9 pages, 8 figures, v2 matches version published in Ap

    A mathematical model for mechanotransduction at the early steps of suture formation

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    Growth and patterning of craniofacial sutures are subjected to the effects of mechanical stress. Mechanotransduction processes occurring at the margins of the sutures are not precisely understood. Here, we propose a simple theoretical model based on the orientation of collagen fibres within the suture in response to local stress. We demonstrate that fibre alignment generates an instability leading to the emergence of interdigitations. We confirm the appearance of this instability both analytically and numerically. To support our model, we use histology and synchrotron x-ray microtomography and reveal the fine structure of fibres within the sutural mesenchyme and their insertion into the bone. Furthermore, using a mouse model with impaired mechanotransduction, we show that the architecture of sutures is disturbed when forces are not interpreted properly. Finally, by studying the structure of sutures in the mouse, the rat, an actinopterygian (\emph{Polypterus bichir}) and a placoderm (\emph{Compagopiscis croucheri}), we show that bone deposition patterns during dermal bone growth are conserved within jawed vertebrates. In total, these results support the role of mechanical constraints in the growth and patterning of craniofacial sutures, a process that was probably effective at the emergence of gnathostomes, and provide new directions for the understanding of normal and pathological suture fusion

    Nonconvex Production Technology and Price Discrimination

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    A modern firm often employs multiple production technologies based on distinct engineering principles, causing non-convexities in the firm's unit cost as a function of product quality. Extending the model of Mussa and Rosen (1978), this paper investigates how a monopolist's product line design may crucially depend on the non-convexities in the unit cost function. We show that the firm does not offer those qualities where the unit cost exceeds its convex envelope. Consequently, there are "gaps" in its optimal quality choice. When the firm is only permitted to offer a limited number of quality levels (due to possible fixed costs associated with offering each quality), the optimal location of quality levels still lies within those regions of the quality domain where the unit cost function coincides with its convex envelope. We further show that the firm's profit is a supermodular function of its quality levels, and characterize a necessary condition for the optimal quality locationPrice Discrimination, Product Line Design, Nonconvex Production

    Relation Between Chiral Susceptibility and Solutions of Gap Equation in Nambu--Jona-Lasinio Model

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    We study the solutions of the gap equation, the thermodynamic potential and the chiral susceptibility in and beyond the chiral limit at finite chemical potential in the Nambu--Jona-Lasinio (NJL) model. We give an explicit relation between the chiral susceptibility and the thermodynamic potential in the NJL model. We find that the chiral susceptibility is a quantity being able to represent the furcation of the solutions of the gap equation and the concavo-convexity of the thermodynamic potential in NJL model. It indicates that the chiral susceptibility can identify the stable state and the possibility of the chiral phase transition in NJL model.Comment: 21 pages, 6 figures, misprints are correcte

    Non-convexities in the Adjustment of Different Capital Inputs: A Firm-level Investigation

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    Recent developments in investment research have highlighted the importance of non-convexities and irreversibilities in the firms’ adjustment of quasi-fixed inputs. However, aggregation across capital goods may smooth out the discontinuities associated with the adjustment of individual assets. The lack of suitable data is one of the reasons why empirical work has strongly relied on the assumption of capital homogeneity. In this paper we exploit a new data set of 1539 Italian firms which allows us to disaggregate capital and consider separately purchases and sales of assets. We disaggregate between equipment and structures and construct measures of fundamental Q to capture investment opportunities associated with each asset. To uncover the pattern of dynamic adjustment we use non-parametric techniques to relate each individual investment to own fundamental Q.Investment, heterogenous capital, non-convexities, fundamental Q, panel data

    Microcanonical Thermostatistics as Foundation of Thermodynamics. The microscopic origin of condensation and phase separations

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    Conventional thermo-statistics address infinite homogeneous systems within the canonical ensemble. However, some 150 years ago the original motivation of thermodynamics was the description of steam engines, i.e. boiling water. Its essential physics is the separation of the gas phase from the liquid. Of course, boiling water is inhomogeneous and as such cannot be treated by canonical thermo-statistics. Then it is not astonishing, that a phase transition of first order is signaled canonically by a Yang-Lee singularity. Thus it is only treated correctly by microcanonical Boltzmann-Planck statistics. This is elaborated in the present article. It turns out that the Boltzmann-Planck statistics is much richer and gives fundamental insight into statistical mechanics and especially into entropy. This can even be done to some extend rigorously and analytically. The microcanonical entropy has a very simple physical meaning: It measures the microscopic uncertainty that we have about the system, i.e. the number of points in 6N6N-dim phase, which are consistent with our information about the system. It can rigorously be split into an ideal-gas part and a configuration part which contains all the physics and especially is responsible for all phase transitions. The deep and essential difference between ``extensive'' and ``intensive'' control parameters, i.e. microcanonical and canonical statistics, is exemplified by rotating, self-gravitating systems.Comment: Invited paper for the conference "Frontiers of Quantum and Mesoscopic Thermodynamics", Prague 26-29 July 2004, 9 pages, 3 figures A detailed discussion of Clausius original papers on entropy are adde

    Post-extraction mesio-distal gap reduction assessment by confocal laser scanning microscopy - a clinical 3-month follow-up study

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    [EN] AimThe aim of this 3-month follow-up study is to quantify the reduction in the mesio-distal gap dimension (MDGD) that occurs after tooth extraction through image analysis of three-dimensional images obtained with the confocal laser scanning microscopy (CLSM) technique. Materials and MethodsFollowing tooth extraction, impressions of 79 patients 1month and 72 patients 3months after tooth extraction were obtained. Cast models were processed by CLSM, and MDGD changes between time points were measured. ResultsThe mean mesio-distal gap reduction 1month after tooth extraction was 343.4m and 3months after tooth extraction was 672.3m. The daily mean gap reduction rate during the first term (between baseline and 1month post-extraction measurements) was 10.3m/day and during the second term (between 1 and 3months) was 5.4m/day. ConclusionsThe mesio-distal gap reduction is higher during the first month following the extraction and continues in time, but to a lesser extent. When the inter-dental contacts were absent, the mesio-distal gap reduction is lower. When a molar tooth is extracted or the distal tooth to the edentulous space does not occlude with an antagonist, the mesio-distal gap reduction is larger. The consideration of mesio-distal gap dimension changes can help improve dental treatment planning.The authors would like to express their gratitude to MEC (contract grant number AP2008-01653), to FEDER, to the Generalitat Valenciana for its help in the CLSM acquisition (MY08/ISIRM/S/100), to the Universitat Politecnica de Valencia (PAID-05-12) and to Dr. Asuncion Jaime for her translation assistance.García-Herraiz, A.; Silvestre, FJ.; Leiva García, R.; Crespo Abril, F.; Garcia-Anton, J. (2017). Post-extraction mesio-distal gap reduction assessment by confocal laser scanning microscopy - a clinical 3-month follow-up study. Journal Of Clinical Periodontology. 44(5):548-555. https://doi.org/10.1111/jcpe.12706S548555445Aguilar, M. L., Elias, A., Vizcarrondo, C. E. T., & Psoter, W. J. (2010). Analysis of three-dimensional distortion of two impression materials in the transfer of dental implants. The Journal of Prosthetic Dentistry, 103(4), 202-209. doi:10.1016/s0022-3913(10)60032-7Amit, G., JPS, K., Pankaj, B., Suchinder, S., & Parul, B. (2012). Periodontally accelerated osteogenic orthodontics (PAOO) - a review. Journal of Clinical and Experimental Dentistry, e292-296. doi:10.4317/jced.50822Armitage, G. C. (1999). Development of a Classification System for Periodontal Diseases and Conditions. Annals of Periodontology, 4(1), 1-6. doi:10.1902/annals.1999.4.1.1Belli, R., Pelka, M., Petschelt, A., & Lohbauer, U. (2009). In vitro wear gap formation of self-adhesive resin cements: A CLSM evaluation. Journal of Dentistry, 37(12), 984-993. doi:10.1016/j.jdent.2009.08.006Belli, R., Rahiotis, C., Schubert, E. W., Baratieri, L. N., Petschelt, A., & Lohbauer, U. (2011). Wear and morphology of infiltrated white spot lesions. Journal of Dentistry, 39(5), 376-385. doi:10.1016/j.jdent.2011.02.009Brauchli, L. M., Baumgartner, E.-M., Ball, J., & Wichelhaus, A. (2011). Roughness of enamel surfaces after different bonding and debonding procedures. Journal of Orofacial Orthopedics / Fortschritte der Kieferorthopädie, 72(1), 61-67. doi:10.1007/s00056-010-0002-3Chen, S. Y., Liang, W. M., & Chen, F. N. (2004). Factors affecting the accuracy of elastometric impression materials. Journal of Dentistry, 32(8), 603-609. doi:10.1016/j.jdent.2004.04.002Christou, P., & Kiliaridis, S. (2007). Three-dimensional changes in the position of unopposed molars in adults. The European Journal of Orthodontics, 29(6), 543-549. doi:10.1093/ejo/cjm036Craddock, H. L., Youngson, C. C., Manogue, M., & Blance, A. (2007). Occlusal Changes Following Posterior Tooth Loss in Adults. Part 2. Clinical Parameters Associated with Movement of Teeth Adjacent to the Site of Posterior Tooth Loss. Journal of Prosthodontics, 16(6), 495-501. doi:10.1111/j.1532-849x.2007.00223.xFaria, A. C. L., Rodrigues, R. C. S., Macedo, A. P., Mattos, M. da G. C. de, & Ribeiro, R. F. (2008). Accuracy of stone casts obtained by different impression materials. Brazilian Oral Research, 22(4), 293-298. doi:10.1590/s1806-83242008000400002García-Herraiz, A., Leiva-García, R., Cañigral-Ortiz, A., Silvestre, F. J., & García-Antón, J. (2011). Confocal laser scanning microscopy for the study of the morphological changes of the postextraction sites. Microscopy Research and Technique, 75(4), 513-519. doi:10.1002/jemt.21085Gragg, K. L., Shugars, D. A., Bader, J. D., Elter, J. R., & White, B. A. (2001). Movement of Teeth Adjacent to Posterior Bounded Edentulous Spaces. Journal of Dental Research, 80(11), 2021-2024. doi:10.1177/00220345010800111401LINDSKOG-STOKLAND, B., HANSEN, K., TOMASI, C., HAKEBERG, M., & WENNSTRÖM, J. L. (2011). Changes in molar position associated with missing opposed and/or adjacent tooth: a 12-year study in women. Journal of Oral Rehabilitation, 39(2), 136-143. doi:10.1111/j.1365-2842.2011.02252.xLove, W. D., & Adams, R. L. (1971). Tooth movement into edentulous areas. The Journal of Prosthetic Dentistry, 25(3), 271-278. doi:10.1016/0022-3913(71)90188-0Nishikawa, T., Masuno, K., Mori, M., Tajime, Y., Kakudo, K., & Tanaka, A. (2006). Calcification at the Interface Between Titanium Implants and Bone: Observation With Confocal Laser Scanning Microscopy. Journal of Oral Implantology, 32(5), 211-217. doi:10.1563/799.1Pereira, J. R., Murata, K. Y., Valle, A. L. do, Ghizoni, J. S., & Shiratori, F. K. (2010). Linear dimensional changes in plaster die models using different elastomeric materials. Brazilian Oral Research, 24(3), 336-341. doi:10.1590/s1806-83242010000300013Schilling, T., Müller, M., Minne, H. W., & Ziegler, R. (1998). Influence of Inflammation-Mediated Osteopenia on the Regional Acceleratory Phenomenon and the Systemic Acceleratory Phenomenon During Healing of a Bone Defect in the Rat. Calcified Tissue International, 63(2), 160-166. doi:10.1007/s002239900508Scivetti, M., Pilolli, G. P., Corsalini, M., Lucchese, A., & Favia, G. (2007). Confocal laser scanning microscopy of human cementocytes: Analysis of three-dimensional image reconstruction. Annals of Anatomy - Anatomischer Anzeiger, 189(2), 169-174. doi:10.1016/j.aanat.2006.09.009SHUGARS, D. A., BADER, J. D., PHILLIPS, S. W., WHITE, B. A., & BRANTLEY, C. F. (2000). THE CONSEQUENCES OF NOT REPLACING A MISSING POSTERIOR TOOTH. The Journal of the American Dental Association, 131(9), 1317-1323. doi:10.14219/jada.archive.2000.0385Thalmair, T., Fickl, S., Schneider, D., Hinze, M., & Wachtel, H. (2013). Dimensional alterations of extraction sites after different alveolar ridge preservation techniques - a volumetric study. Journal of Clinical Periodontology, 40(7), 721-727. doi:10.1111/jcpe.12111Thongthammachat, S., Moore, B. K., Barco, M. T., Hovijitra, S., Brown, D. T., & Andres, C. J. (2002). Dimensional accuracy of dental casts: Influence of tray material, impression material, and time. Journal of Prosthodontics, 11(2), 98-108. doi:10.1053/jopr.2002.125192Van der Weijden, F., Dell’Acqua, F., & Slot, D. E. (2009). Alveolar bone dimensional changes of post-extraction sockets in humans: a systematic review. Journal of Clinical Periodontology, 36(12), 1048-1058. doi:10.1111/j.1600-051x.2009.01482.xWeinstein, S. (1967). Minimal forces in tooth movement. American Journal of Orthodontics, 53(12), 881-903. doi:10.1016/0002-9416(67)90163-7Windisch, S. I., Jung, R. E., Sailer, I., Studer, S. P., Ender, A., & Hämmerle, C. H. F. (2007). A new optical method to evaluate three-dimensional volume changes of alveolar contours: a methodological in vitro study. Clinical Oral Implants Research, 18(5), 545-551. doi:10.1111/j.1600-0501.2007.01382.xYAMADA, M. K., & WATARI, F. (2003). Imaging and Non-Contact Profile Analysis of Nd: YAG Laser-Irradiated Teeth by Scanning Electron Microscopy and Confocal Laser Scanning Microscopy. Dental Materials Journal, 22(4), 556-568. doi:10.4012/dmj.22.55
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