Topological Constraints on the Dynamics of Vortex Formation in a Two-Dimensional Quantum Fluid.

We present experimental and theoretical results on formation of quantum vortices in a laser beam propagating in a nonlinear medium. Topological constrains richer than the mere conservation of vorticity impose an elaborate dynamical behavior to the formation and annihilation of vortex-antivortex pairs. We identify two such mechanisms, both described by the same fold-Hopf bifurcation. One of them is particularly efficient although it is not observed in the context of liquid helium films or stationary systems because it relies on the compressible nature of the fluid of light we consider and on the nonstationarity of its flow.

Oscillating Solitons and ac Josephson Effect in Ferromagnetic Bose-Bose Mixtures.

Close to the demixing transition, the degree of freedom associated with relative density fluctuations of a two-component Bose-Einstein condensate is described by a nondissipative Landau-Lifshitz equation. In the quasi-one-dimensional weakly immiscible case, this mapping surprisingly predicts that a dark-bright soliton should oscillate when subject to a constant force favoring separation of the two components. We propose a realistic experimental implementation of this phenomenon which we interpret as a spin-Josephson effect in the presence of a movable barrier.

Quantitative Analysis of Shock Wave Dynamics in a Fluid of Light.

We report on the formation of a dispersive shock wave in a nonlinear optical medium. We monitor the evolution of the shock by tuning the incoming beam power. The experimental observations for the position and intensity of the solitonic edge of the shock, as well as the location of the nonlinear oscillations are well described by recent developments of Whitham modulation theory. Our work constitutes a detailed and accurate benchmark for this approach. It opens exciting possibilities to engineer specific configurations of optical shock wave for studying wave-mean flow interaction.

Departing from Thermality of Analogue Hawking Radiation in a Bose-Einstein Condensate.

We study the quantum fluctuations in a one-dimensional Bose-Einstein condensate realizing an analogous acoustic black hole. The taking into account of evanescent channels and of zero modes makes it possible to accurately reproduce recent experimental measurements of the density correlation function. We discuss the determination of Hawking temperature and show that in our model the analogous radiation presents some significant departure from thermality.

Evolution of initial discontinuities in the Riemann problem for the Kaup-Boussinesq equation with positive dispersion.

We consider the space-time evolution of initial discontinuities of depth and flow velocity for an integrable version of the shallow water Boussinesq system introduced by Kaup. We focus on a specific version of this "Kaup-Boussinesq model" for which a flat water surface is modulationally stable, we speak below of "positive dispersion" model. This model also appears as an approximation to the equations governing the dynamics of polarisation waves in two-component Bose-Einstein condensates. We describe its periodic solutions and the corresponding Whitham modulation equations. The self-similar, one-phase wave structures are composed of different building blocks, which are studied in detail. This makes it possible to establish a classification of all the possible wave configurations evolving from initial discontinuities. The analytic results are confirmed by numerical simulations.

Quantum Signature of Analog Hawking Radiation in Momentum Space.

We consider a sonic analog of a black hole realized in the one-dimensional flow of a Bose-Einstein condensate. Our theoretical analysis demonstrates that one- and two-body momentum distributions accessible by present-day experimental techniques provide clear direct evidence (i) of the occurrence of a sonic horizon, (ii) of the associated acoustic Hawking radiation, and (iii) of the quantum nature of the Hawking process. The signature of the quantum behavior persists even at temperatures larger than the chemical potential.

Long-time evolution of pulses in the Korteweg-de Vries equation in the absence of solitons reexamined: Whitham method.

We consider the long-time evolution of pulses in the Korteweg-de Vries equation theory for initial distributions which produce no soliton but instead lead to the formation of a dispersive shock wave and of a rarefaction wave. An approach based on Whitham modulation theory makes it possible to obtain an analytic description of the structure and to describe its self-similar behavior near the soliton edge of the shock. The results are compared with numerical simulations.

Solution of the Riemann problem for polarization waves in a two-component Bose-Einstein condensate.

We provide a classification of the possible flows of two-component Bose-Einstein condensates evolving from initially discontinuous profiles. We consider the situation where the dynamics can be reduced to the consideration of a single polarization mode (also denoted as "magnetic excitation") obeying a system of equations equivalent to the Landau-Lifshitz equation for an easy-plane ferromagnet. We present the full set of one-phase periodic solutions. The corresponding Whitham modulation equations are obtained together with formulas connecting their solutions with the Riemann invariants of the modulation equations. The problem is not genuinely nonlinear, and this results in a non-single-valued mapping of the solutions of the Whitham equations with physical wave patterns as well as the appearance of interesting elements-contact dispersive shock waves-that are absent in more standard, genuinely nonlinear situations. Our analytic results are confirmed by numerical simulations.

Integration and expression of provirus in human cells transformed by avian sarcoma virus.

Previously, human diploid fibroblasts from some donors infected in vitro by avian sarcoma virus (ASV) were transformed and found, by electron microscopy, to produce small numbers of virus particles that were infectious by bioassay; also, a line of human osteosarcoma cells infected with ASV developed additional characteristics of transformation and released a small number of infectious virus particles. In this study the complete proviral sequence was shown to be integrated in the genome of these cells. The env-related proteins gp85 and gp37 and the gag-related proteins pr76, pr60, and p19 can be detected in cytoplasmic extracts of ASV-infected human cells. Comparable amounts of pp60v-src were found in human and avian cells infected with ASV. The associated kinase activity in infected human cells was dramatically increased as compared to that of uninfected controls; the enzyme had the same cation and substrate requirements as those from ASV-transformed avian cells. Replicating particles from infected human cells were purified and were significantly modified compared to those from avian hosts as shown by a) higher specific gravity, b) the presence of RSV gag-related but not env-related antigens, and c) the fact that the virus-associated reverse transcriptase preferred the divalent cations Mn2+ and Fe2+ over Mg2+.

Fas-mediated apoptosis in human prostatic carcinoma cell lines.

Of six prostatic carcinoma cell lines examined (ALVA31, DU145, JCA1, LNCaP, ND1, and PC3) by flow cytometric analysis, all were found to be positive for Fas antigen. Furthermore, of the prostate tissue specimens studied (six cases), all revealed Fas expression in benign and malignant epithelial cells. The agonistic anti-Fas monoclonal antibody (IPO-4) induced apoptosis in only two of six cell lines investigated, PC3 and ALVA31. PCR analysis indicated that all cell lines expressed normal transmembrane and death domains of Fas antigen. Using Western blot analysis, we found abundant expression of p53 in the cytoplasm of two Fas-resistant cell lines, DU145 and ND1, and did not find p53 in two Fas-sensitive cell lines, PC3 and ALVA31. Western blot and PCR analysis did not show consistent differences between cell lines examined in the expression of Bcl-2, Bcl-X(L), Bcl-X(S), and Bak. In contrast, Bax protein was not detected in two Fas-resistant cell lines, DU145 and ND1. We also showed that three Fas-resistant cell lines, DU145, ND1, and JCA1, expressed CD40, whereas the two Fas-sensitive cell lines, PC3 and ALVA31, were CD40 negative. Fas-sensitive cell lines were transfected with the cDNA encoding CD40, and the CD40-positive transfectant became more resistant to growth inhibition mediated by treatment with TNF-alpha and anti-Fas monoclonal antibody. Treatment with cycloheximide converted the phenotype of resistant cell lines from Fas resistant to Fas sensitive. Moreover, anti-Fas treatment of both resistant and sensitive cell lines induced rapid tyrosine phosphorylation or dephosphorylation of multiple proteins. These results suggest that the apoptotic machinery involved in DNA fragmentation is already in place in Fas-resistant cell lines, and thus, Fas-mediated apoptosis could be a target for therapeutic intervention.

Porphyromonas gingivalis: a proteinase/gene accounting audit.

Analysis of the available data on the Porphyromonas gingivalis proteinase system suggests that at most three different genes encode arginine-X- and lysine-X-specific cysteine proteinases. These are synthesized as polyproteins containing a prepropeptide, a catalytic domain and a hemagglutinin domain. Post-translational processing of each precursor is responsible for the variety of proteinase forms that are seen.

Maspin is an intracellular serpin that partitions into secretory vesicles and is present at the cell surface.

The tumor suppressor maspin (mammary serpin) was originally identified as a component of human mammary epithelial cells that is downregulated as mammary tumor cells progress from the benign to the invasive and metastatic states. Maspin inhibits cellular invasion, motility, and proliferation, but its mechanism of action is currently unknown. Because the cellular machinery responsible for these processes is cytoplasmic, we have reexamined the tissue distribution and subcellular localization of maspin. We find that maspin, or a maspin-like protein, is present in many human organs, in which it localizes to epithelia. In cultured human mammary myoepithelial cells, maspin is predominantly a soluble cytoplasmic protein that associates with secretory vesicles and is present at the cell surface. In vitro assays show that the vesicle association is due to the existence of an uncleaved facultative secretion signal that allows small amounts of maspin to partition into the endoplasmic reticulum. These results demonstrate that maspin is more widespread than previously believed. The subcellular localization studies indicate that soluble intracellular and vesicle-associated maspin probably play an important role in controlling the invasion, motility, and proliferation of cells expressing it, whereas extracellular maspin may also regulate these processes in adjacent cells.

Sequence analysis of the large and small subunits of human ribonucleotide reductase.

We have isolated and sequenced overlapping cDNA clones from a breast carcinoma cDNA library containing the entire coding region of both the R1 and R2 subunits of the human ribonucleotide reductase gene. The coding region of the human R1 subunit comprises 2376 nucleotides and predicts a polypeptide of 792 amino acids (calculated molecular mass 90,081). The sequence of this subunit is almost identical to the equivalent mouse ribonucleotide reductase subunit with 97.7% homology between the mouse and human R1 subunit amino acid sequences. The coding region of the human R2 subunit of ribonucleotide reductase comprises 1170 nucleotides and predicts a polypeptide of 389 amino acids (calculated molecular mass 44,883), which is one amino acid shorter than the equivalent mouse subunit. The human and mouse R2 subunits display considerable homology in their carboxy-terminal amino acid sequences, with 96.3% homology downstream of amino acid 68 of the human and mouse R2 proteins. However, the amino-terminal portions of these two proteins are more divergent in sequence, with only 69.2% homology in the first 68 amino acids.

Dipole oscillations of a Bose-Einstein condensate in the presence of defects and disorder.

We consider dipole oscillations of a trapped dilute Bose-Einstein condensate in the presence of a scattering potential consisting either in a localized defect or in an extended disordered potential. In both cases the breaking of superfluidity and the damping of the oscillations are shown to be related to the appearance of a nonlinear dissipative flow. At supersonic velocities the flow becomes asymptotically dissipationless.

Superfluidity versus Anderson localization in a dilute Bose gas.

We consider the motion of a quasi-one-dimensional beam of Bose-Einstein condensed particles in a disordered region of finite extent. Interaction effects lead to the appearance of two distinct regions of stationary flow. One is subsonic and corresponds to superfluid motion. The other one is supersonic and dissipative and shows Anderson localization. We compute analytically the interaction-dependent localization length. We also explain the disappearance of the supersonic stationary flow for large disordered samples.

Simultaneous overexpression of avian pp60c-src and polyomavirus middle T antigen in mammalian cells.

Recombinant adenoviruses bearing the avian c-src gene and polyomavirus middle-T-antigen gene were isolated and used to simultaneously overexpress both proteins in human 293 cells. Cells overexpressing both proteins had greater middle-T-antigen-associated tyrosine kinase activity than cells overexpressing only middle T antigen. By contrast, the intrinsic pp60c-src tyrosine kinase activity was not greater in cells overexpressing both proteins than in cells overexpressing only pp60c-src. This system of simultaneous overexpression provides a means of obtaining large quantities of pp60c-src, middle T antigen, and the complex between them.

Isolation of proteins with kinase activity and related to pp60 src from human cells.

A protein kinase activity (PK) was associated with immunoprecipitates between polypeptides of human lymphoblastoid cells of malignant origin (Raji cell line) or of their normal counterparts ( Priess cell line) and antibodies directed against avian pp60 src or against the carboxyterminal hexapeptide of pp60 src. Therefore, these human cells and Rous Sarcoma Virus (RSV) transformed avian cells share antigenic determinants of pp60 src and, in particular, its carboxyterminal sequence, as well as one of its functions, a protein kinase activity. The protein kinase from Raji cells phosphorylated predominantly tyrosine residues, that from Priess cells threonine residues.