Differential resistance to cell entry by porcine endogenous retrovirus subgroup A in rodent species

Background: The risk of zoonotic infection by porcine endogenous retroviruses (PERV) has been highlighted in the context of pig-to-human xenotransplantation. The use of receptors for cell entry often determines the host range of retroviruses. A human-tropic PERV subgroup, PERV-A, can enter human cells through either of two homologous multitransmembrane proteins, huPAR-1 and huPAR-2. Here, we characterised human PARs and their homologues in the PERV-A resistant rodent species, mouse and rat ( muPAR and ratPAR, respectively). Results: Upon exogenous expression in PERV-A resistant cells, human and rat PARs, but not muPAR, conferred PERV-A sensitivity. Exogenously expressed ratPAR binds PERV-A Env and allows PERV-A infection with equivalent efficiency to that of huPAR-1. Endogenous ratPAR expression in rat cell lines appeared to be too low for PERV-A infection. In contrast, the presence of Pro at position 109 in muPAR was identified to be the determinant for PERV-A resistance. Pro109. was shown to be located in the second extracellular loop (ECL2) and affected PERV-A Env binding to PAR molecules. Conclusion: The basis of resistance to PERV-A infection in two rodent species is different. Identification of a single a. a. mutation in muPAR, which is responsible for mouse cell resistance to PERV-A highlighted the importance of ECL-2 for the viral receptor function

Virtual audio reproduced in a headrest

When virtual audio reproduction is simultaneously required in many seats, such as in aircraft or cinemas, it may be convenient to use loudspeakers mounted inside each seat's headrest. In this preliminary study, the feasibility of virtual audio reproduction in the headrest of a single seat is explored using an inversion technique to compensate for crosstalk and the synthesis of head related transfer functions. Although large changes in the magnitude of the signals reproduced at the listener's ears are observed as the listener moves their head within the headrest, informal listening tests indicate that the reproduced acoustic images are surprisingly stable in about an eighth of an arc either side of the loudspeaker positions. Not surprisingly, frontal images are more difficult to reproduce with headrest loudspeakers

Morita equivalences induced by bimodules over Hopf-Galois extensions

Let $H$ be a Hopf algebra, and $A,B$ be $H$-Galois extensions. We investigate the category ${}_A\mathcal{M}_B^H$ of relative Hopf bimodules, and the Morita equivalences between $A$ and $B$ induced by them.Comment: 32 page

Quantitative and qualitative characteristics of greenery in suburban residential districts of Metro Manila

This case study was conducted to better understand the present situation of urban greenery in Marikina City, in the suburbs of metropolitan Manila, a typical large Asian city. A vegetation survey was conducted in residential districts of Marikina City, and the quantitative and qualitative characteristics of trees were analyzed. Lot size had some influence on the quantity of greenery in residential lots. In smaller lots, however, quantity did not increase in proportion to lot size. It appears, then, that the land-use controls for individual lots did not function effectively. Quantitative differences of greenery were related to qualitative differences, depending on the year or period of development of the residential area. In the newly developed residential lots, the greenery is comprised mostly of ornamental trees. Under the present circumstances, there is no assurance of sustaining the desired quantity of greenery in smaller residential lots. From these results, we proposed that regulations on lot size/coverage and promotion of tree planting involving local residents are needed to sustain urban greenery in residential districts

Far-Ultraviolet and Far-Infrared Bivariate Luminosity Function of Galaxies: Complex Relation between Stellar and Dust Emission

Far-ultraviolet (FUV) and far-infrared (FIR) luminosity functions (LFs) of galaxies show a strong evolution from $z = 0$ to $z = 1$, but the FIR LF evolves much stronger than the FUV one. The FUV is dominantly radiated from newly formed short-lived OB stars, while the FIR is emitted by dust grains heated by the FUV radiation field. It is known that dust is always associated with star formation activity. Thus, both FUV and FIR are tightly related to the star formation in galaxies, but in a very complicated manner. In order to disentangle the relation between FUV and FIR emissions, we estimate the UV-IR bivariate LF (BLF) of galaxies with {\sl GALEX} and {\sl AKARI} All-Sky Survey datasets. Recently we invented a new mathematical method to construct the BLF with given marginals and prescribed correlation coefficient. This method makes use of a tool from mathematical statistics, so called "copula". The copula enables us to construct a bivariate distribution function from given marginal distributions with prescribed correlation and/or dependence structure. With this new formulation and FUV and FIR univariate LFs, we analyze various FUV and FIR data with {\sl GALEX}, {\sl Spitzer}, and {\sl AKARI} to estimate the UV-IR BLF. The obtained BLFs naturally explain the nonlinear complicated relation between FUV and FIR emission from star-forming galaxies. Though the faint-end of the BLF was not well constrained for high-$z$ samples, the estimated linear correlation coefficient $\rho$ was found to be very high, and is remarkably stable with redshifts (from 0.95 at $z = 0$ to 0.85 at $z = 1.0$). This implies the evolution of the UV-IR BLF is mainly due to the different evolution of the univariate LFs, and may not be controlled by the dependence structure.Comment: 10 pages, 7 figures, Earth, Planets and Space, in pres

Position and Momentum Uncertainties of the Normal and Inverted Harmonic Oscillators under the Minimal Length Uncertainty Relation

We analyze the position and momentum uncertainties of the energy eigenstates of the harmonic oscillator in the context of a deformed quantum mechanics, namely, that in which the commutator between the position and momentum operators is given by [x,p]=i\hbar(1+\beta p^2). This deformed commutation relation leads to the minimal length uncertainty relation \Delta x > (\hbar/2)(1/\Delta p +\beta\Delta p), which implies that \Delta x ~ 1/\Delta p at small \Delta p while \Delta x ~ \Delta p at large \Delta p. We find that the uncertainties of the energy eigenstates of the normal harmonic oscillator (m>0), derived in Ref. [1], only populate the \Delta x ~ 1/\Delta p branch. The other branch, \Delta x ~ \Delta p, is found to be populated by the energy eigenstates of the `inverted' harmonic oscillator (m<0). The Hilbert space in the 'inverted' case admits an infinite ladder of positive energy eigenstates provided that \Delta x_{min} = \hbar\sqrt{\beta} > \sqrt{2} [\hbar^2/k|m|]^{1/4}. Correspondence with the classical limit is also discussed.Comment: 16 pages, 31 eps figure

Experimental comparison of icing cloud instruments

Icing cloud instruments were tested in the spray cloud Icing Research Tunnel (IRT) in order to determine their relative accuracy and their limitations over a broad range of conditions. It was found that the average of the readings from each of the liquid water content (LWC) instruments tested agreed closely with each other and with the IRT calibration; but all have a data scatter (+ or - one standard deviation) of about + or - 20 percent. The effect of this + or - 20 percent uncertainty is probably acceptable in aero-penalty and deicer experiments. Existing laser spectrometers proved to be too inaccurate for LWC measurements. The error due to water runoff was the same for all ice accretion LWC instruments. Any given laser spectrometer proved to be highly repeatable in its indications of volume median drop size (DVM), LWC and drop size distribution. However, there was a significant disagreement between different spectrometers of the same model, even after careful standard calibration and data analysis. The scatter about the mean of the DVM data from five Axial Scattering Spectrometer Probes was + or - 20 percent (+ or - one standard deviation) and the average was 20 percent higher than the old IRT calibration. The + or - 20 percent uncertainty in DVM can cause an unacceptable variation in the drag coefficient of an airfoil with ice; however, the variation in a deicer performance test may be acceptable

X-Ray Fluctuations from Locally Unstable Advection-Dominated Disks

The response of advection-dominated accretion disks to local disturbances is examined by one-dimensional numerical simulations. It is generally believed that advection-dominated disks are thermally stable. We, however, find that any disurbance added onto accretion flow at large radii does not decay so rapidly that it can move inward with roughly the free-fall velocity. Although disturbances continue to be present, the global disk structure will not be modified largely. This can account for persistent hard X-ray emission with substantial variations observed in active galactic nuclei and stellar black hole candidates during the hard state. Moreover, when the disturbance reaches the innermost parts, an acoustic wave emerges, propagating outward as a shock wave. The resultant light variation is roughly (time) symmetric and is quite reminiscent of the observed X-ray shots of Cygnus X-1.Comment: plain TeX, 11 pages, without figures; to be published in ApJ Lette