ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

A new phase extraction algorithm for phase profilometry (1997)

Di Stefano, Luigi ; Boland, Frank

Springer

Machine vision and applications 10 (1997), S. 188-200

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ISSN: 1432-1769

Keywords: Key words:3D optical profilometry – Active ranging – Structured light – Phase profilometry – Automatic inspection

Source: Springer Online Journal Archives 1860-2000

Topics: Computer Science

Notes: Abstract. This paper describes a new phase extraction algorithm for 3D optical profilometry based on the projection of a periodic light pattern and phase measurement (phase profilometry). The algorithm uses a square wave to demodulate phase and moving averages and comb-shaped filters to extract the phase information from low frequency. The proposed algorithm is compared with the two major profilometry techniques, namely Fourier domain profilometry and signal domain profilometry based on FIR low-pass filtering. Comparison is focused on adaptiveness to changes of the pattern frequency, ability to deal with nonuniform surfaces and computational complexity. Adaptiveness analysis is carried out by means of simulations. The issue of nonuniform surfaces is discussed on the basis of experimental results obtained from application of phase profilometry to on-line 3D printed circuit board inspection. With regard to complexity, theoretical estimates are verified by means of actual computation time measurements.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s001380050071

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2

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Calcium and Magnesium: Low Passive Permeability and Tubular Secretion in the Mouse Medullary Thick Ascending Limb of Henle's Loop (MTAL) (1996)

Wittner, M. ; Desfleurs, E. ; Pajaud, S. ; [et al.]

Springer

The journal of membrane biology 153 (1996), S. 27-35

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ISSN: 1432-1424

Keywords: Key words: Medullary thick ascending limb — Ca2+ transport — Mg2+ transport — Electron microprobe analysis — Passive permeability — ADH

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Chemistry and Pharmacology

Notes: Abstract. Recent studies from our laboratory have shown that in the mouse and rat nephron Ca2+ and Mg2+ are not reabsorbed in the medullary part of the thick ascending limb (mTAL) of Henle's loop. The aim of the present study was to investigate whether the absence of transepithelial Ca2+ and Mg2+ transport in the mouse mTAL is due to its relative low permeability to divalent cations. For this purpose, transepithelial ion net fluxes were measured by electron probe analysis in isolated perfused mouse mTAL segments, when the transepithelial potential difference (PDte.) was varied by chemical voltage clamp, during active NaCl transport inhibition by luminal furosemide. The results show that transepithelial Ca2+ and Mg2+ net fluxes in the mTAL are not driven by the transepithelial PDte. At zero voltage, a small but significant net secretion of Ca2+ into the tubular lumen was observed. With a high lumen-positive PDte generated by creating a transepithelial bath-to-lumen NaCl concentration gradient, no Ca2+ and Mg2+ reabsorption was noted; instead significant and sustained Ca2+ and Mg2+ net secretion occurred. When a lumen-positive PDte was generated in the absence of apical furosemide, but in the presence of a transepithelial bath-to-lumen NaCl concentration gradient, a huge Ca2+ net secretion and a lesser Mg2+ net secretion, not modified by ADH, were observed. Replacement of Na+ by K+ in the lumen perfusate induced, in the absence of PDte changes, important but reversible net secretions of Ca2+ and Mg2+. In conclusion, our results indicate that the passive permeability of the mouse mTAL to divalent cations is very low and not influenced by ADH. This nephron segment can secrete Ca2+ and Mg2+ into the luminal fluid under conditions which elicit large lumen-positive transepithelial potential differences. Given the impermeability of this epithelium to Ca2+ and Mg2+, the secretory processes would appear to be of cellular origin.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002329900106

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3

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Line strengths of diatomics: The b 1Σ+v′=0→X 3Σ−v″=0 transition of the NF radical (1997)

Di Stefano, G.

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 107 (1997), S. 2752-2759

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ISSN: 1089-7690

Source: AIP Digital Archive

Topics: Physics , Chemistry and Pharmacology

Notes: Line intensities in the (0,0) band of NF(b 1Σ+→X 3Σ−) spin forbidden emission have been observed in a microwave apparatus. Deduced line strengths of the OP and SR well resolved branches are shown differently, in contrast with the theoretical prevision, and are interpreted by taking into account some peculiarities of the NF radical. An intermediate (a) and (b) Hund case is seen to apply toOP and SR in the whole rotational range examined. Accordingly, a reliable value for the effective transition momentμe is evaluated from the experiment. © 1997 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.475127

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4

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Densitometric Study of Developing Femur (1999)

Panattoni, G. L. ; D'Amelio, P. ; Di Stefano, M. ; [et al.]

Springer

Calcified tissue international 64 (1999), S. 133-136

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ISSN: 1432-0827

Keywords: Key words: Human fetus — Femur — Densitometry.

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine , Physics

Notes: Abstract. The purpose of this work was to extend to long bones the study on the ossification of human fetal skeleton in relation to conceptual age by a quantitative methodological approach. Postero-anterior scans were performed on 29 dried fetal femora (from 11.5 weeks of conceptual age to term) by a Hologic QDR 1000 X-ray densitometer with Ultra-Hi-Resolution software. The results were expressed as bone mineral content (BMC, g) and bone mineral density (BMD, g/cm2). BMD was calculated on a rectangular area corresponding to the total length and minimum width of the shaft. This area was divided into five equal sections along its longitudinal axis in order to estimate the rate of ossification from a spatio-temporal point of view. Our data show that BMC has a high correlation with conceptual age during the whole prenatal life, increasing in the third trimester (r ≥ 0.96). During development, BMD is progressively less correlated with conceptual age (r = 0.95 in the first half of development, r = 0.68 in the second half), particularly according to a bidirectional gradient from the middle to the proximal and distal ends of the shaft. Our findings confirm the data obtained in our previous studies on the ossification of fetal human spines, and suggest an individual variability in bone density at term of development and particularly at the level of spongiosa, viz. in the areas mostly involved in architectural changes during the morphogenesis of the long bones.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002239900591

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5

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Imbalance in dosage of the genes for the heterochromatin components Sir3p and histone H4 results in changes in the length and sequence organization of yeast telomeres (1999)

Venditti, S. ; Vega-Palas, M. A. ; Di Stefano, G. ; [et al.]

Springer

Molecular genetics and genomics 262 (1999), S. 367-377

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ISSN: 1617-4623

Keywords: Key words Heterochromatin ; Histone gene imbalance ; Telomere length ; Telomere sequence organization ; Y′ elements

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Telomeric heterochromatin plays an essential role in telomere function, including the regulation of telomere length. We observe that in Saccharomyces cerevisiae an imbalance in the dosage of genes for two protein components of heterochromatin (namely Sir3p and histone H4) causes modifications in telomere length and telomere sequence organization. The effects of Sir3p/H4 imbalance were analyzed in yeast strains in which the wild-type SIR3 gene (normally a single-copy gene) was either absent or present in 20–30 copies, and both histone H4 genes (HHF1 and HHF2) were present or HHF1 was deleted, thus covering a wide range of viable gene-dosage combinations. Modifications of telomeres and of subtelomeric regions were identified by analyzing both the overall telomere population and by focusing on two single telomeric regions: the left telomere of chromosome III (LIII) and the right telomere of chromosome XI (RXI). The modifications induced by alteration of the Sir3p/H4 ratio consist of a reduction in the length and an increase in the instability of the terminal block of (C1–3A)n repeats and in susceptibility to insertion of Y′ elements into this repeat element. Restoration of the wild-type gene ratio (by removal of the extra copies of SIR3 or by complementation with the missing second copy of HHF) restored the original telomere organization, both with respect to the length of the (C1–3A)n repeat stretch and the absence of Y′ elements. This behavior shows that the stability of the wild-type sequence organization requires maintenance of the normal structure of telomeric heterochromatin.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004380051095

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6

Electronic Resource

Five-beam magneto-optical trap and optical molasses (1999)

di Stefano, A. ; Wilkowski, D. ; Müller, J.H. ; [et al.]

Springer

Applied physics 69 (1999), S. 263-268

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ISSN: 1432-0649

Keywords: PACS: 32.80Pj; 42.50.Vk

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract. We have operated a magneto-optical trap and optical molasses for the laser cooling of cesium atoms on the basis of a five-beam laser configuration. For the magneto-optical trap two laser beams counterpropagate along the axis of a quadrupole trap and the remaining three beams propagate in the orthogonal plane at 120° to each other. The same optical configuration was used for the optical molasses. We have tested the efficiency in atom collection and the temperatures reached in both cooling processes. In comparison to previous results on a six-beam configuration, a lower number of atoms is collected, while comparable densities are realized. The atomic temperatures have been measured through a delayed shadow-image technique, where one of the running-wave cooling beams produces an absorptive image of the atoms on a camera.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s003400050806

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7

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Bone cell behavior on Matrigel®-coated Ca/P coatings of varying crystallinities (1998)

Maxian, Suzanne H. ; Di Stefano, Tony ; Melican, Mora C. ; [et al.]

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 40 (1998), S. 171-179

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ISSN: 0021-9304

Keywords: hydroxyapatite ; titanium ; calvarial cells ; cell-specific alkaline phosphatase activity ; bone-related proteins gene expression ; Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Medicine , Technology

Notes: Rat calvarial cell mitogenic behavior was investigated on various biomaterials coated with Matrigel®, a basement membrane matrix containing growth factors. Low (20-40%) and high (70-90%) crystallinity hydroxyapatite (rHA and cHA), rough titanium (Ti), and tissue culture polystyrene (TP) surfaces were compared. Surface chemistry and calcium resorption of HA coatings, alkaline phosphatase activity (APA), and growth of cells were measured for Matrigel®-coated and uncoated surfaces at 2, 7, and 14 days. Gene expression for four noncollagenous bone-related proteins (osteonectin, osteopontin, alkaline phosphatase, and osteocalcin) was also investigated by reverse transcription and polymerase chain reaction up to 28 days. Ca concentration in incubating solutions increased with time for the two types of HA coatings and was always greater for rHA than cHA. Surface chemistry and coating dissolution rates were not affected by the presence of Matrigel® or cells throughout the study. APA of cells on the two HA-coated surfaces was comparably enhanced in the presence of Matrigel® and was greater than on Ti surfaces. Only HA surfaces showed an increased APA of cells with time in the presence of Matrigel®. Cell growth peaked at 7 days and was greatest for cells on the two HA surfaces and without Matrigel®. At 14 days, cell growth was comparable on the four surfaces. The presence of HA and Matrigel® enhanced cell-specific APA at 14 days. Gene expression for all four proteins investigated showed no differences between surfaces after 7 days. At 2 and 7 days, gene expression was indicative of proliferation for Ti, and of proliferation, differentiation, and mineralization for HA and TP more so without Matrigel®. The addition of this matrix significantly enhanced mitogenicity of calvarial cells on HA only after 14 days. Matrigel® eliminated differences seen between the two HA coatings. Gene expression was not enhanced or inhibited by the presence of Matrigel®. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 171-179, 1998.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

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