Quantifying slope-channel coupling in an active gully and fan complex at Tarndale, Waipaoa catchment, New Zealand

Two RIEGL LMS‐Z420i scanner surveys (November 2007 and November 2008) of the Tarndale Gully complex and its associated fan were used to generate a digital elevation model (DEM) of difference in order to quantify gully‐fan‐channel connectivity. The Te Weraroa Stream, into which the first order Tarndale system feeds, is buffered from sediment generated by the gully complex by a fan. Sediment yields and the role of the fan in buffering Te Weraroa Stream are inferred from the TLS of the entire complex. DEM analysis suggests that c.25% of material derived from the gully is buffered from the stream by being stored in the fan. This figure was applied to fan behaviour since December 2004, mapped on nine successive occasions using detailed GPS surveys to get a longer‐term picture of sediment supply within the system and appraise a qualitative assessment of connectivity constructed on the basis of fan behaviour alone

Terahertz lasing from intersubband polariton-polariton scattering in asymmetric quantum wells

Electric dipole transitions between different cavity polariton branches or between dressed atomic states with the same excitation number are strictly forbidden in centro-symmetric systems. For doped quantum wells in semiconductor microcavities, the strong coupling between an intersubband transition in the conduction band and a cavity mode produces two branches of intersubband cavity polaritons, whose normal-mode energy splitting is tunable and can be in the terahertz region. Here, we show that, by using asymmetric quantum wells, it is possible to have allowed dipolar transitions between different polaritonic branches, leading to the emission of terahertz photons. We present a quantum field theory for such a system and predict that high-efficiency, widely tunable terahertz lasing can be obtained

The nuclear spectrum of the radio galaxy NGC 5128 (Centaurus A)

We present near-infrared spectra of the nuclear disk in the nearby radio galaxy NGC 5128 (Centaurus A). On the basis of the observed strengths of the [S III] 0.9532um and [Fe II] 1.2567um lines, we classify NGC 5128 as a LINER. Modeling of the strengths of these and additional lines suggests that the nuclear region is powered by shocks rather than photoionization.Comment: 12 pages including 2 figures, accepted by ApJ Letter

Suppression of RNA interference increases alphavirus replication and virus-associated mortality in Aedes aegypti mosquitoes

<p>Abstract</p> <p>Background</p> <p>Arthropod-borne viruses (arboviruses) can persistently infect and cause limited damage to mosquito vectors. RNA interference (RNAi) is a mosquito antiviral response important in restricting RNA virus replication and has been shown to be active against some arboviruses. The goal of this study was to use a recombinant Sindbis virus (SINV; family <it>Togaviridae</it>; genus <it>Alphavirus</it>) that expresses B2 protein of Flock House virus (FHV; family <it>Nodaviridae</it>; genus <it>Alphanodavirus</it>), a protein that inhibits RNAi, to determine the effects of linking arbovirus infection with RNAi inhibition.</p> <p>Results</p> <p>B2 protein expression from SINV (TE/3'2J) inhibited the accumulation of non-specific small RNAs in <it>Aedes aegypti </it>mosquito cell culture and virus-specific small RNAs both in infected cell culture and <it>Ae. aegypti </it>mosquitoes. More viral genomic and subgenomic RNA accumulated in cells and mosquitoes infected with TE/3'2J virus expressing B2 (TE/3'2J/B2) compared to TE/3'2J and TE/3'2J virus expressing GFP. TE/3'2J/B2 exhibited increased infection rates, dissemination rates, and infectious virus titers in mosquitoes following oral bloodmeal. Following infectious oral bloodmeal, significantly more mosquitoes died when TE/3'2J/B2 was ingested. The virus was 100% lethal following intrathoracic inoculation of multiple mosquito species and lethality was dose-dependent in <it>Ae. aegypti</it>.</p> <p>Conclusion</p> <p>We show that RNAi is active in <it>Ae. aegypti </it>cell culture and that B2 protein inhibits RNAi in mosquito cells when expressed by a recombinant SINV. Also, SINV more efficiently replicates in mosquito cells when RNAi is inhibited. Finally, TE/3'2J/B2 kills mosquitoes in a dose-dependent manner independent of infection route and mosquito species.</p