ALBERT

Notes: One of the key features of the new economy seems to be the change from individual to collective efficiency: the joint performance of systems of networked enterprises. That movement has an international dimension mainly related to the new strategies of transnational corporations. from the perspective of developing countries important changes might be taking place, as a consequence of the positioning of their firms in that new interorganisational networking. This is the focus of this study. An analytical model was developed for the assessment of which industrial segment shows the potential to be an international player for having the required organisational competencies. The conceptual framework was built around the idea that participation in an interorganisational network depends on the competencies built by each firm and influences the conditions for strategy formulation. A survey about the recent evolution of industry in Brazil was prepared. The outcomes reveal the relative position of the Brazilian firms in international networks, what leads to an overall picture of the competitiveness of local industry.

Notes: Our recent reports of highly energetic spin fluctuations in cuprate insulators closely related to high-Tc superconductors have raised the possibility that the strong spin interactions thus manifested may mediate the superconducting pairing. In La2CuO4 the exchange measured by light scattering is 1100 cm−1, while in Ba2YCu3O6 it is 950 cm−1. In the case of Ba2YCu3O6+x it was also shown that the fluctuations persist at room temperature when carriers have been introduced to make the material superconducting. The fluctuations in this case exhibit a broad spectrum shifted to lower frequency, with no clearly defined peak in the spectrum. In this paper, we shall (1) review the theory of two-magnon light scattering and the selection rules applicable to the cuprates, (2) present the data described above, and (3) present data on other related systems, including Eu2CuO4, La2NiO4, and the superconducting phase of Ba2YCu3O6.7 (for T〈Tc =60 K). Although the newest data show quite unequivocally that the spin fluctuations persist in the superconductor, there is as yet no detailed explanation of the observed line shape. Certainly, a simple first-order calculation for a spin-half Heisenberg square lattice gives a peak that is far narrower than that observed. Although a calculation based on a resonating valence bond model describes our line shape in insulating La2CuO4, other evidence contravenes this interpretation. It is thus not yet possible to say definitively whether the magnetic interaction is the root cause of the high-Tc phenomena. What is clear is that our data represent a clear and well-defined challenge for any detailed theoretical description of the cuprates.

Notes: Amorphous thin films of DyxFe100−x and Dy20Fe80−yCoy, with various x and y values and of ∼40 nm thickness, have been prepared by sputtering on polyimide films. Their magnetization curves and the Mössbauer spectra indicate that at 295 K the iron moments are preferentially oriented parallel to the film in Dy2Fe98 and that Dy6Fe94 is paramagnetic. The DyxFe100−x thin films, where x is 17, 20, 24, 29, 32, 35, and 37, show perpendicular magnetic anisotropies and moderate coercive fields of at most 150 kA/m, whereas the Dy20Fe80−yCoy thin films, where y is 8, 13, 16, and 20, thin films show stronger perpendicular anisotropies and larger coercive fields of ∼400 kA/m. The introduction of cobalt into the amorphous thin films increases their coercive field and the perpendicular magnetic anisotropy. The Mössbauer spectra of the DyxFe100−x and Dy20Fe80−yCoy amorphous thin films consist of broadened sextets which have been analyzed with a distribution of hyperfine fields by assuming that the iron moments are oriented perpendicular to the plane of the film. Detailed fits of the Mössbauer spectrum of Dy20Fe80 indicate that the cone angle of the iron magnetic moments cannot be determined with accuracy. The average hyperfine fields in the DyxFe100−x amorphous thin films are smaller than those in the crystalline dysprosium–iron intermetallic compounds. The average hyperfine field increases from ∼140 kOe in the DyxFe100−x films to ∼220 kOe in the Dy20Fe80−yCoy films, an increase which is in agreement with the increase in the saturation magnetization. The x dependence of the isomer shift indicates that there is strong dysprosium–iron bonding, whereas the y dependence of the isomer shift reveals an enhancement of the d-electron localization. From earlier x-ray magnetic circular dichroism results and the Mössbauer spectral results presented herein, iron magnetic moments of 0.87 or 0.67 μB, corresponding to 2.9 or 2.8 holes in the iron 3d band, have been obtained for the DyxFe100−x amorphous thin films with x greater or smaller than 27, respectively. © 2001 American Institute of Physics.

Notes: For a finite number of particles on the line pairwise interacting with 1/r2 potential, the positions are given by the eigenvalues of some time-dependent matrix. Infinite periodic or doubly periodic replication of the particles yields Calogero–Moser systems with periodic or doubly periodic interaction potential. We are thus led to consider matrices of infinite order, which are identified with Fourier series with matrix coefficients, depending on an additional parameter. These distributional loops of matrices (tori of matrices in the doubly periodic case) are shown to obey simple (partial) differential equations, which allow us to determine them explicitly. Thus we obtain the already known solution of the Calogero–Moser system on the circle, and provide a new insight for the system on the torus. © 2001 American Institute of Physics.

Notes: . Protists provide the opportunity to integrate analyses from a low (molecular) to a high (organism) level of complexity within a broad evolutionary framework. The perpectives they offer in the cytoskeletal field are discussed with respect to emerging concepts of cellular biology.

Notes: . In euplotid ciliates, the cortex is reinforced by alveolar plates—proteinaceous scales located within the membranous alveolar sacs, forming a monolayer just below the plasma membrane. This system appears to play a cytoskeletal role analogous to that provided by the fibrous epiplasm found beneath the cortical alveoli in other ciliates. In Euplotes aediculatus, the major alveolar plate proteins (termed α-,β-, and γ-plateins) have been identified. Using anti-platein antibodies, an expression library of Euplotes genes was screened, and a platein gene identified, cloned, and completely sequenced. Comparison of its derived amino acid sequence with micro-sequences obtained directly from purified plateins identified this gene as encoding one of the closely related β-or μ-plateins. The derived protein, of 644 amino acids (74.9 kDa), is very acidic (pI = 4.88). Microsequences from authentic ot-platein were then used to design oligonucleotide primers, which yielded, via a PCR-based approach, the sequences of two α-platein genes from E. aediculatus. Even more acidic proteins, the derived al- and a2-plateins contain 536 and 501 residues, respectively. Analyses of their amino acid sequences revealed the plateins to be members of the articulin superfamily of cytoskeletal proteins, first described in Euglena and now identified in the ciliate Pseudomicrothorax and in Plasmodium. The hallmark articulin repetitive motifs (based on degenerate valine-and proline-rich 12-mers) are present in all three plateins. In β/γ-platein this primary motif domain (27 repeats) is central in the molecule, whereas the primary repeats in the α-plateins lie near their C-termini. A cluster of proline-rich pentameric secondary repeats is found in the C-terminus of pAy-platein, but near the N-terminus of a-plateins. All three plateins contain canonical N-terminal signal sequences, unique among known cytoskeletal proteins. The presence of start-transfer sequences correlates well with the final intra-alveolar location of these proteins. This feature, and significant differences from known articulins in amino acid usage and arrangement within the repeat domains, lead us to propose that the plateins comprise a new family of articulin-related proteins. Efforts to follow microscopically the assembly of plateins into new alveolar plates during pre-fission morphogenesis are underway.