Multiple solutions for asteroid orbits: Computational procedure and applications

We describe the Multiple Solutions Method, a one-dimensional sampling of the six-dimensional orbital confidence region that is widely applicable in the field of asteroid orbit determination. In many situations there is one predominant direction of uncertainty in an orbit determination or orbital prediction, i.e., a ``weak'' direction. The idea is to record Multiple Solutions by following this, typically curved, weak direction, or Line Of Variations (LOV). In this paper we describe the method and give new insights into the mathematics behind this tool. We pay particular attention to the problem of how to ensure that the coordinate systems are properly scaled so that the weak direction really reflects the intrinsic direction of greatest uncertainty. We also describe how the multiple solutions can be used even in the absence of a nominal orbit solution, which substantially broadens the realm of applications. There are numerous applications for multiple solutions; we discuss a few problems in asteroid orbit determination and prediction where we have had good success with the method. In particular, we show that multiple solutions can be used effectively for potential impact monitoring, preliminary orbit determination, asteroid identification, and for the recovery of lost asteroids

Low-frequency modes in the Raman spectrum of sp-sp2 nanostructured carbon

A novel form of amorphous carbon with sp-sp2 hybridization has been recently produced by supersonic cluster beam deposition showing the presence in the film of both polyynic and cumulenic species [L. Ravagnan et al. Phys. Rev. Lett. 98, 216103 (2007)]. Here we present a in situ Raman characterization of the low frequency vibrational region (400-800 cm-1) of sp-sp2 films at different temperatures. We report the presence of two peaks at 450 cm-1 and 720 cm-1. The lower frequency peak shows an evolution with the variation of the sp content and it can be attributed, with the support of density functional theory (DFT) simulations, to bending modes of sp linear structures. The peak at 720 cm-1 does not vary with the sp content and it can be attributed to a feature in the vibrational density of states activated by the disorder of the sp2 phase.Comment: 15 pages, 5 figures, 1 tabl

Challenges in Dental Statistics: Survey Methodology Topics

This paper gathers some contributions concerning survey methodology in dental research, as discussed during the first Workshop of the SISMEC STATDENT working group on statistical methods and applications in dentistry, held in Ancona on the 28th September 2011. The first contribution deals with the European Global Oral Health Indicators Development (EGOHID) Project which proposed a comprehensive and standardized system of epidemiological tools (questionnaires and clinical forms) for national data collection on oral health in Europe. The second contribution regards the design and conduct of trials to evaluate the clinical efficacy and safety of toothbrushes and mouthrinses. Finally, a flexible and effective tool used to trace dental age reference charts tailored to Italian children was presented

Challenges in Dental Statistics: Survey Methodology Topics

This paper gathers some contributions concerning survey methodology in dental research, as discussed during the first Workshop of the SISMEC STATDENT working group on statistical methods and applications in dentistry, held in Ancona on the 28th September 2011. The first contribution deals with the European Global Oral Health Indicators Development (EGOHID) Project which proposed a comprehensive and standardized system of epidemiological tools (questionnaires and clinical forms) for national data collection on oral health in Europe. The second contribution regards the design and conduct of trials to evaluate the clinical efficacy and safety of toothbrushes and mouthrinses. Finally, a flexible and effective tool used to trace dental age reference charts tailored to Italian children was presented

IDENTIFICATION OF A NOVEL GM3 SYNTHASE mRNA ISOFORM FROM HUMAN PLACENTA AND FUNCTIONAL ANALYSIS OF THE 5\u2019-FLANKING REGION OF THE TRANSCRIPT

GM3 synthase is a key enzyme in the biosynthesis of gangliosides that, as mediators of cell-cell interactions and modulators of signaling transduction, play fundamental roles in many both physiological and pathological cellular processes (i.e., proliferation, differentiation, oncogenesis) (1,2). GM3 synthase results expressed in a tissue-specific manner, especially in brain, muscle, testis, and placenta, and only one transcript, of about 2.4 kb, has been detected in all the tissues. Up to date GM3 synthase cDNA has been isolated and characterized from both TPA-differentiated HL-60 cells and human fetal and adult brain (3,4) and five mRNA variants have been identified. They differ in the 5\u2019-untranslated region, but all of them predict a 41.7 kDa protein having substrate activity highly restricted to lactosylceramide. On the contrary, our study, directed to the isolation of the full length GM3 synthase cDNA from human placenta, led to the identification of an unusual GM3 synthase mRNA variant that strongly differs from all the other GM3 synthase transcripts until now identified. In fact, its 5\u2019-terminal region introduces a new translation initiation site located upstream and in-frame with that usually considered as translation initiation codon in the GM3 synthase gene. Studies of in vitro translation and in vivo expression indicate that the human placental cDNA leads to the synthesis of two polypeptides with apparent molecular mass, in SDS-PAGE, of 42.1 and 38.3 kDa, respectively. Moreover, the stable transfection of the human placental cDNA into mammalian MG1361 cells resulted in a threefold increase of GM3 synthase activity, associated to a broader substrate specificity, and, more importantly, in significant alterations of cell ganglioside profile. Therefore, our data provide the first demonstration of the existence of two GM3 synthase isoforms and indicate that, at least in the human placenta, they apparently derive from a single transcript. In addition, to elucidate the mechanism that regulates the tissue-specific expression of the human GM3 synthase gene we isolated the genomic DNA region (~3 kb) flanking the placental GM3 synthase transcript. Sequence analysis with the MatInspector 2.2 program revealed that this region lacks canonical TATA e CAAT boxes, but contains several putative transcription factor binding sites including AP1, GATA1, NFAT, MZF1, IK2; unfortunately no placenta-specific transcription factor is reported in none of the available transcription factor databases. Up to date, functional analysis of the isolated genomic region has been assessed in human placental choriocarcinoma JEG3 cells by transient transfection, but preliminary data seem to indicate that it doesn\u2019t promote transcription of the reporter SEAP gene. Future plans are to analyze the functional activity of DNA fragments containing varying lengths of the 5\u2019-flanking genomic sequence in both JEG3 cells and other suitable cell lines so to evaluate the eventual presence of positive and negative regulatory elements and factors in both the DNA sequence and the cell line. 1) Hakomori S.I. (2000) Glycoconj. J. 17, 143. 2) Hakomori S.I. (2000) Glycoconj. J. 17, 627. 3) Ishii A. et al. (1998) J. Biol. Chem. 273, 31652. 4) Kapitonov D. et al.(1999) Glycoconj J. 16, 337

GM3 IN THE REGULATION OF THE EXPRESSION AND ACTIVATION OF ErbB-2/EGFR HETERODIMERS

Gangliosides are a large and heterogeneous family of sialic acid containing glycosphingolipids, ubiquitous components of all eukaryotic cell membranes. They can partially segregate, together with cholesterol and specific signaling transduction proteins, such as receptor tyrosine-kinases, into unique more or less stable clusters or microdomains, indicated as \u201cglycolipid-enriched domains\u201d, \u201clipid rafts\u201d, \u201ccaveolae\u201d, contributing to the membrane structure, organization and function (1). Gangliosides are well-characterized modulators of receptor tyrosine-kinase (RTKs) phophorylation and dimerization (2). Our interest is particularly directed to study the relationship between gangliosides and two members of the tyrosine kinase ErbB receptor family: the epidermal growth factor receptor, EGFR or ErbB-1, and the structurally related protein ErbB-2. Unlike EGFR, ErbB-2 is a ligandless receptor: it can be activated by heterodimerization and cross-phosphorylation by other ligand-activated ErbB receptors (3,4). Our previous experimental evidence supports the functional relationship between ErbB-2 and gangliosides, in particular GM3 (5,6). In the present study, using the HC11 mouse mammary epithelial cell line, we investigated the ErbB-2 activation state and its tendency to form stable molecular complexes with EGFR and with ganglioside GM3, before and after EGF stimulation, by co-immunoprecipitation experiments with anti-ErbB-2 antibody and Western blot analyses. As HC11 cells express different ganglioside species, the exclusive association of GM3 with ErbB-2 and EGFR was ascertained by high performance-thin layer chromatography (HP-TLC) and TLC-immunostaining analyses of gangliosides extracted from the immunoprecipitates. Results display that in EGF-stimulated HC11 cells stable and tyrosine-phosphorylated ErbB2/EGFR dimers are formed and that GM3 is the unique ganglioside tightly associated to ErbB-2/EGFR dimers and to EGFR monomers, but not to ErbB2 monomers. In cells not stimulated with EGF a spontaneous but unproductive dimerization of ErbB2 and EGFR takes place and no ganglioside is found associated to the receptors. These observations indicate that the modulation of ErbB2 activation by GM3 may be mediated by EGFR, but that EGF stimulation is indispensable. After ganglioside depletion by [D]-PDMP, phosphorylated EGFR monomers are observed both before and after EGF stimulation, whereas ErbB-2 is present in the monomeric and unphosphorylated state even after EGF stimulation, suggesting that GM3 might have a bivalent key role in modulating the activation of ErbB-2 and EGFR. References 1. Fivaz, M., Abrami, L., Van Der Goot. F.G. Trends Cell Biol. 9(6), 212-213 (1999); 2. Bremer, E.G., Current topics in membranes 40, 387-411(1999); 3. Qian, X., LeVea, C.M., Freeman, J.K., Dougall, W.C., Greene, M.I., Proc. Natl. Acad. Sci. USA 91, 1500-1504 (1994); 4. Gulliford, T.J., Huang, G.C., Ouyang, X., Epstein, R.J., Oncogene 15, 2219-2223 (1997); 5. Sottocornola E., Berra B., and Colombo I., Biochim. Biophys. Acta-Molecolar and cell Biology of Lipids, 1635, 55-66 (2003); 6. Sottocornola E., Misasi R., Mattei V., Ciarlo L., Gradini R., Garofalo T., Berra B., Colombo I., and Sorice M., FEBS J. 273, 1821-1830 (2006)

American Pygmy Shrew, Sorex hoyi, Consumed by an Arctic Grayling, Thymallus arcticus

Arctic Grayling, Thymallus arcticus, are rarely reported to consume small mammals. We report an American Pygmy Shrew, Sorex hoyi, consumed by an Arctic Grayling caught in southern Yukon, Canada. This is the first record of an American Pygmy Shrew being consumed by an Arctic Grayling, and it confirms that Arctic Grayling will consume shrews (Sorex spp.) when they are available. We suspect that the body size of prey is a limiting factor in Arctic Grayling consuming small mammals, with some species of shrews being small enough for Arctic Grayling to consume

Chirikov Diffusion in the Asteroidal Three-Body Resonance (5,-2,-2)

The theory of diffusion in many-dimensional Hamiltonian system is applied to asteroidal dynamics. The general formulations developed by Chirikov is applied to the Nesvorn\'{y}-Morbidelli analytic model of three-body (three-orbit) mean-motion resonances (Jupiter-Saturn-asteroid system). In particular, we investigate the diffusion \emph{along} and \emph{across} the separatrices of the (5,-2,-2) resonance of the (490) Veritas asteroidal family and their relationship to diffusion in semi-major axis and eccentricity. The estimations of diffusion were obtained using the Melnikov integral, a Hadjidemetriou-type sympletic map and numerical integrations for times up to $10^{8}$ years.Comment: 27 pages, 6 figure