Adhesion and invasion of bovine endothelial cells by Neospora caninum

Neospora caninum is a recently identified coccidian parasite which was, until 1988, misdiagnosed as Toxoplasma gondii. It causes paralysis and death in dogs and neonatal mortality and abortion in cattle, sheep, goats and horses. The life-cycle of Neospora has not yet been elucidated. The only two stages identified so far are tissue cysts and intracellularly dividing tachyzoites. Very little is known about the biology of this species. We have set up a fluorescence-based adhesion/invasion assay in order to investigate the interaction of N. caninum tachyzoites with bovine aorta endothelial (BAE) cells in vitro. Treatment of both host cells and parasites with metabolic inhibitors determined the metabolic requirements for adhesion and invasion. Chemical and enzymatic modifications of parasite and endothelial cell surfaces were used in order to obtain information on the nature of cell surface components responsible for the interaction between parasite and host. Electron microscopical investigations defined the ultrastructural characteristics of the adhesion and invasion process, and provided information on the intracellular development of the parasite

The possible importance of synchrotron/inverse Compton losses to explain fast mm-wave and hard X-ray emission of a solar event

The solar burst of 21 May 1984, presented a number of unique features. The time profile consisted of seven major structures (seconds), with a turnover frequency of greater than or approximately 90 GHz, well correlated in time to hard X-ray emission. Each structure consisted of multiple fast pulses (0.1 seconds), which were analyzed in detail. A proportionality between the repetition rate of the pulses and the burst fluxes at 90 GHz and greater than or approximately 100 keV hard X-rays, and an inverse proportionality between repetition rates and hard X-ray power law indices were found. A synchrotron/inverse Compton model was applied to explain the emission of the fast burst structures, which appear to be possible for the first three or four structures

Observations of OJ 287 from the Geodetic VLBI Archive of the Washington Correlator

We present 27 geodetic VLBI maps of OJ 287 obtained from the archive of the Washington correlator. The observations presented here were made between 1990 October and 1996 December. During this period a sequence of six superluminal components has been identified. We measured the proper motion of these components to be approximately 0.5 mas/yr, which is about twice as high as that seen in previous VLBI observations. These results imply a higher component ejection rate than previously observed, in good agreement with the observed occurrences of radio outbursts. We have examined a possible connection between VLBI components and optical flares in the framework of a binary black hole system.Comment: 9 pages, 5 included figures, emulateapj.sty, accepted to The Astrophysical Journa

The possible importance of synchrotron/inverse Compton losses to explain fast MM-wave and hard X-ray emission of a solar event

The solar burst of 21 May 1984 presented a number of unique features. The time profile consisted of seven major structures (seconds), with a turnover frequency or approx. 90 GHz, well correlated in time to hard X-ray emission. Each structure consisted of multiple fast pulses (.1 seconds), which were analyzed in detail. A proportionality between the repetition rate of the pulses and the burst fluxes at 90 GHz and or approx. 100 keV hard X-rays, and an inverse proportionality between repetition rates and hard X-rays power law indices have been found. A synchrotron/inverse Compton model has been applied to explain the emission of the fast burst structures, which appear to be possible for the first three or four structures

A new class of solar burst with MM-wave emission but only at the highest frequency (90 GHz)

High sensitivity and high time resolution solar observations at 90 GHz (lambda = 3.3 mm) have identified a unique impulsive burst on May 21, 1984 with emission that was more intense at this frequency than at lower frequencies. The first major time structure of the burst was over 10 times more intense at 90 GHz than at 30 GHz, 7 GHz, or 2.8 GHz.Only 6 seconds later, the 30 GHz impulsive structures started to be observed but still with lower intensity than at 90 GHz. Hard X-ray time structures at energies above 25 keV were almost identical to the 90 GHZ structures (to better than one second). All 90 GHz major time structures consisted of trains of multiple subsecond pulses with rise times as short as 0.03 sec and amplitudes large compared to the mean flux. When detectable, the 30 GHz subsecond pulses had smaller relative amplitude and were in phase with the corresponding 90 GHz pulses

The Drinfel'd Double and Twisting in Stringy Orbifold Theory

This paper exposes the fundamental role that the Drinfel'd double \dkg of the group ring of a finite group $G$ and its twists \dbkg, \beta \in Z^3(G,\uk) as defined by Dijkgraaf--Pasquier--Roche play in stringy orbifold theories and their twistings. The results pertain to three different aspects of the theory. First, we show that $G$--Frobenius algebras arising in global orbifold cohomology or K-theory are most naturally defined as elements in the braided category of \dkg--modules. Secondly, we obtain a geometric realization of the Drinfel'd double as the global orbifold $K$--theory of global quotient given by the inertia variety of a point with a $G$ action on the one hand and more stunningly a geometric realization of its representation ring in the braided category sense as the full $K$--theory of the stack $[pt/G]$. Finally, we show how one can use the co-cycles $\beta$ above to twist a) the global orbifold $K$--theory of the inertia of a global quotient and more importantly b) the stacky $K$--theory of a global quotient $[X/G]$. This corresponds to twistings with a special type of 2--gerbe.Comment: 35 pages, no figure

Non-equilibrium Relaxation Study of Ferromagnetic Transition in Double-Exchange Systems

Ferromagnetic transition in double-exchange systems is studied by non-equilibrium relaxation technique combined with Monte Carlo calculations. Critical temperature and critical exponents are estimated from relaxation of the magnetic moment. The results are consistent with the previous Monte Carlo results in thermal equilibrium. The exponents estimated by these independent techniques suggest that the universality class of this transition is the same as that of short-range interaction models but is different from the mean-field one.Comment: 3 pages including 1 figure, submitted to J. Phys. Soc. Jp

Vector competence of Aedes japonicus for chikungunya and dengue viruses

The Asian bush mosquito Aedes japonicus japonicus (Theobald, 1901) [=Ochlerotatus japonicus (sensu Reinert et al., 2004) =Hulecoeteomyia japonica (sensu Reinert et al., 2006)], has invaded large parts of North America and has recently started to spread in Central-Western Europe. The species is suspected to act as a bridge vector of West Nile virus but nothing or very little is known about its vector competence for Chikungunya and Dengue viruses. Here, we report on experiments of laboratory infections of Ae. japonicus with CHIKV and DENV, demonstrating that the species has a vector potential for both viruses. Considering the high abundance of the species in urban environments and its ability to feed on human, these results plead to include this species when processing risk assessments for mosquito-borne diseases

Precise Experimental Investigation of Eigenmodes in a Planar Ion Crystal

The accurate characterization of eigenmodes and eigenfrequencies of two-dimensional ion crystals provides the foundation for the use of such structures for quantum simulation purposes. We present a combined experimental and theoretical study of two-dimensional ion crystals. We demonstrate that standard pseudopotential theory accurately predicts the positions of the ions and the location of structural transitions between different crystal configurations. However, pseudopotential theory is insufficient to determine eigenfrequencies of the two-dimensional ion crystals accurately but shows significant deviations from the experimental data obtained from resolved sideband spectroscopy. Agreement at the level of 2.5 x 10^(-3) is found with the full time-dependent Coulomb theory using the Floquet-Lyapunov approach and the effect is understood from the dynamics of two-dimensional ion crystals in the Paul trap. The results represent initial steps towards an exploitation of these structures for quantum simulation schemes.Comment: 5 pages, 4 figures, supplemental material (mathematica and matlab files) available upon reques