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1.
In this paper we describe, from a theoretical point of view, critical configurations for the projective reconstruction of
a set of points, for a single view, i.e. for calibration of a camera, in the case of projections from ℙk to ℙ2 for k ≥ 4. We give first a general result describing these critical loci in ℙk, which, if irreducible, are algebraic varieties of dimension k−2 and degree 3. If k=4 they can be either a smooth ruled surface or a cone and if k = 5 they can be a smooth three dimensional variety, ruled in planes, or a cone. If k≥ 6, the variety is always a cone, the
vertex of which has dimension at least k − 6. The reducible cases are studied in Appendix A.
These results are then applied to determine explicitly the critical loci for the projections from ℙk which arise from the dynamic scenes in ℙ3 considered in [13].
Marina Bertolini is currently Associate Professor of Geometry at the Department of Mathematics at the Università degli Studi di Milano, Italy.
Her main field of research is Complex Projective Algebraic Geometry, with particular interest for the classification of projective
varieties and for the geometry of Grassmann varieties. On these topics M. Bertolini has published more than twenty reviewed
papers on national and international journals. She has been for some years now interested also in applications of Algebraic
Geometry to Computer Vision problems.
Cristina Turrini is Associate Professor of Geometry at the Department of Mathematics of Università degli Studi di Milano, Italy. Her main
research interest is Complex Projective Algebraic Geometry: subvarieties of Grassmannians, special varieties, automorphisms,
classification. In the last two years she has started to work on applications of Algebraic Geometry to problems of Computer
Vision. She is author or co-author of about thirty reviewed papers. She is also involved in popularization of Mathematics,
and on this subject she is co-editor of some books. 相似文献
2.
G. Carelli N. Ioli J. C. S. Moraes A. Moretti F. Strumia G. E. Annino A. Bertolini 《Journal of Infrared, Millimeter and Terahertz Waves》1996,17(6):1023-1030
The results described in this work are part of a systematic search for long wavelength laser lines to be used in high magnetic field EPR applications and in plasma diagnostic. Four new far-infrared laser lines of CH2 = CF2 (1,1 difluoroethylene), optically pumped by a waveguide CO2 laser, have been discovered and characterized in wavelength, polarization relative to the pumping radiation and offset relative to the CO2 center frequency. New measurements of polarization and offset of 5 already known laser lines are also reported. A table of all of the known CO2 pumped FIR laser lines from this molecule is given. 相似文献
3.
The influence of alloying of Pt with 20 at.% of Ni, Co and Fe has been studied in the hydrogenation of 1,3 butadiene. Iron induces the more important modifications, with both higher activity and selectivity. The results are discussed in terms of the surface segregation, the local order in surface and the electronic properties measured by photoemission of core levels. 相似文献
4.
Roberta Squecco Alessia Tani Flaminia Chellini Rachele Garella Eglantina Idrizaj Irene Rosa Sandra Zecchi-Orlandini Mirko Manetti Chiara Sassoli 《International journal of molecular sciences》2021,22(7)
Bone marrow-mesenchymal stem/stromal cells (MSCs) may offer promise for skeletal muscle repair/regeneration. Growing evidence suggests that the mechanisms underpinning the beneficial effects of such cells in muscle tissue reside in their ability to secrete bioactive molecules (secretome) with multiple actions. Hence, we examined the effects of MSC secretome as conditioned medium (MSC-CM) on ex vivo murine extensor digitorum longus muscle injured by forced eccentric contraction (EC). By combining morphological (light and confocal laser scanning microscopies) and electrophysiological analyses we demonstrated the capability of MSC-CM to attenuate EC-induced tissue structural damages and sarcolemnic functional properties’ modifications. MSC-CM was effective in protecting myofibers from apoptosis, as suggested by a reduced expression of pro-apoptotic markers, cytochrome c and activated caspase-3, along with an increase in the expression of pro-survival AKT factor. Notably, MSC-CM also reduced the EC-induced tissue redistribution and extension of telocytes/CD34+ stromal cells, distinctive cells proposed to play a “nursing” role for the muscle resident myogenic satellite cells (SCs), regarded as the main players of regeneration. Moreover, it affected SC functionality likely contributing to replenishment of the SC reservoir. This study provides the necessary groundwork for further investigation of the effects of MSC secretome in the setting of skeletal muscle injury and regenerative medicine. 相似文献
5.
Constant L. Ruiz P. Abel M. Robach Y. Porte L. Bertolini J.C. 《Topics in Catalysis》2000,14(1-4):125-129
The catalytic properties, with respect to the 1,3-butadiene hydrogenation reaction, of strained Pd films on Cu(110) (lattice mismatch 8%) has been probed as a function of the film thickness. The characterization of the adlayer has been made by the combined use of STM with LEED and AES. For deposits below 1015 Pd/cm2 (i.e., about 1 ML) the catalytic activity is near zero. This is the consequence of the formation of a Pd–Cu surface alloy with tendency for Cu to migrate/segregate to the surface. The catalytic activity suddenly increases to reach a maximum value for about 3 ML; the activity is then one order of magnitude higher than that of the pure Pd(110) surface. This is the consequence of the presence of a strained Pd overlayer, with Pd surface atoms having very unusual geometry, and hence very peculiar electronic and chemical properties. The catalytic activity then decreases as the Pd coverage is increased, and tends to values near that of the pure Pd(110). Gradual relaxation of the film geometry towards that of the normal fcc Pd structure probably exists. 相似文献
6.
7.
I. Frosio A. Alzati M. Bertolini C. Turrini N.A. Borghese 《Pattern recognition》2012,45(12):4169-4181
We propose here a new method to recover the orientation and position of a plane by matching at least three projections of a conic lying on the plane itself. The procedure is based on rearranging the conic projection equations such that the non linear terms are eliminated. It works with any kind of conic and does not require that the shape of the conic is known a-priori. The method was extensively tested using ellipses, but it can also be used for hyperbolas and parabolas. It was further applied to pairs of lines, which can be viewed as a degenerate case of hyperbola, without requiring the correspondence problem to be solved first. Critical configurations and numerical stability have been analyzed through simulations. The accuracy of the proposed algorithm was compared to that of traditional algorithms and of a trinocular vision system using a set of landmarks. 相似文献
8.
Giulia Gizzi Samuela Cataldi Claudia Mazzeschi Elisa Delvecchio Maria Rachele Ceccarini Michela Codini Elisabetta Albi 《International journal of molecular sciences》2022,23(13)
The relationship between cholesterol and cancer has been widely demonstrated. Clinical studies have shown changes in blood cholesterol levels in cancer patients. In parallel, basic research studies have shown that cholesterol is involved in the mechanisms of onset and progression of the disease. On the other hand, anorexic patients have high cholesterol levels and a high susceptibility to cancer. In this review, we first present a brief background on the relations among nutrition, eating disorders and cancer. Using several notable examples, we then illustrate the changes in cholesterol in cancer and in anorexia nervosa, providing evidence for their important relationship. Finally, we show a new possible link between cholesterol disorder in cancer and in anorexia nervosa. 相似文献
9.
Lisa Biasetto Rachele Bertolini Hamada Elsayed Andrea Ghiotti Stefania Bruschi 《Ceramics International》2019,45(5):5941-5951
Rods of commercially pure titanium were machined using standard oil-based emulsion and cryogenic cooling, and were then coated with sphene (CaTiSiO5) bioceramic by spray coating using an automatic airbrush. The sphene bioceramic was synthesized in-situ starting from a suspension of polysiloxane that used as SiO2 precursor, CaCO3 and TiO2 nanoparticles. The suspension was deposited on the machined substrates, which were heat treated up to 950?°C in order to promote the formation of sphene ceramic. The produced coated prototypes were characterized to evaluate the effect of the machining conditions on surface roughness and microstructure of the substrate, and thereby their effect on coating adhesion. Nanoindentation tests were employed to determine the hardness and elastic modulus of the coating through its thickness. Results showed that the reduced amount of defects on the surface of the cryo-machined substrates, contributed to increase the hardness, elastic modulus and adhesion strength of the coating-substrate interfaces compared to standard machined samples, therefore improving adhesion of the coating to the underlying substrate. 相似文献
10.