Field-induced water electrolysis switches an oxide semiconductor from an insulator to a metal

Here we demonstrate that water-infiltrated nanoporous glass electrically switches an oxide semiconductor from an insulator to metal. We fabricated the field effect transistor structure on an oxide semiconductor, SrTiO3, using 100%-water-infiltrated nanoporous glass - amorphous 12CaO*7Al2O3 - as the gate insulator. For positive gate voltage, electron accumulation, water electrolysis and electrochemical reduction occur successively on the SrTiO3 surface at room temperature, leading to the formation of a thin (~3 nm) metal layer with an extremely high electron concentration of 10^15-10^16 cm^-2, which exhibits exotic thermoelectric behaviour.Comment: 21 pages, 12 figure

A dust-parallax distance of 19 megaparsecs to the supermassive black hole in NGC 4151

The active galaxy NGC 4151 has a crucial role as one of only two active galactic nuclei for which black hole mass measurements based on emission line reverberation mapping can be calibrated against other dynamical methods. Unfortunately, effective calibration requires an accurate distance to NGC 4151, which is currently not available. Recently reported distances range from 4 to 29 megaparsecs (Mpc). Strong peculiar motions make a redshift-based distance very uncertain, and the geometry of the galaxy and its nucleus prohibit accurate measurements using other techniques. Here we report a dust-parallax distance to NGC 4151 of $D_A = 19.0^{+2.4}_{-2.6}$ Mpc. The measurement is based on an adaptation of a geometric method proposed previously using the emission line regions of active galaxies. Since this region is too small for current imaging capabilities, we use instead the ratio of the physical-to-angular sizes of the more extended hot dust emission as determined from time-delays and infrared interferometry. This new distance leads to an approximately 1.4-fold increase in the dynamical black hole mass, implying a corresponding correction to emission line reverberation masses of black holes if they are calibrated against the two objects with additional dynamical masses.Comment: Authors' version of a letter published in Nature (27 November 2014); 8 pages, 5 figures, 1 tabl

The AFLOW Fleet for Materials Discovery

The traditional paradigm for materials discovery has been recently expanded to incorporate substantial data driven research. With the intent to accelerate the development and the deployment of new technologies, the AFLOW Fleet for computational materials design automates high-throughput first principles calculations, and provides tools for data verification and dissemination for a broad community of users. AFLOW incorporates different computational modules to robustly determine thermodynamic stability, electronic band structures, vibrational dispersions, thermo-mechanical properties and more. The AFLOW data repository is publicly accessible online at aflow.org, with more than 1.7 million materials entries and a panoply of queryable computed properties. Tools to programmatically search and process the data, as well as to perform online machine learning predictions, are also available.Comment: 14 pages, 8 figure

Determining factors of thermoelectric properties of semiconductor nanowires

It is widely accepted that low dimensionality of semiconductor heterostructures and nanostructures can significantly improve their thermoelectric efficiency. However, what is less well understood is the precise role of electronic and lattice transport coefficients in the improvement. We differentiate and analyze the electronic and lattice contributions to the enhancement by using a nearly parameter-free theory of the thermoelectric properties of semiconductor nanowires. By combining molecular dynamics, density functional theory, and Boltzmann transport theory methods, we provide a complete picture for the competing factors of thermoelectric figure of merit. As an example, we study the thermoelectric properties of ZnO and Si nanowires. We find that the figure of merit can be increased as much as 30 times in 8-Å-diameter ZnO nanowires and 20 times in 12-Å-diameter Si nanowires, compared with the bulk. Decoupling of thermoelectric contributions reveals that the reduction of lattice thermal conductivity is the predominant factor in the improvement of thermoelectric properties in nanowires. While the lattice contribution to the efficiency enhancement consistently becomes larger with decreasing size of nanowires, the electronic contribution is relatively small in ZnO and disadvantageous in Si

Transmitted Drug Resistance in Persons with Acute/Early HIV-1 in San Francisco, 2002-2009

Transmitted HIV-1 drug resistance (TDR) is an ongoing public health problem, representing 10-20% of new HIV infections in many geographic areas. TDR usually arises from two main sources: individuals on antiretroviral therapy (ART) who are failing to achieve virologic suppression, and individuals who acquired TDR and transmit it while still ART-naïve. TDR rates can be impacted when novel antiretroviral medications are introduced that allow for greater virologic suppression of source patients. Although several new HIV medications were introduced starting in late 2007, including raltegravir, maraviroc, and etravirine, it is not known whether the prevalence of TDR was subsequently affected in 2008-2009.We performed population sequence genotyping on individuals who were diagnosed with acute or early HIV (<6 months duration) and who enrolled in the Options Project, a prospective cohort, between 2002 and 2009. We used logistic regression to compare the odds of acquiring drug-resistant HIV before versus after the arrival of new ART (2005-2007 vs. 2008-2009). From 2003-2007, TDR rose from 7% to 24%. Prevalence of TDR was then 15% in 2008 and in 2009. While the odds of acquiring TDR were lower in 2008-2009 compared to 2005-2007, this was not statistically significant (odds ratio 0.65, 95% CI 0.31-1.38; p = 0.27).Our study suggests that transmitted drug resistance rose from 2003-2007, but this upward trend did not continue in 2008 and 2009. Nevertheless, the TDR prevalence in 2008-2009 remained substantial, emphasizing that improved management strategies for drug-resistant HIV are needed if TDR is to be further reduced. Continued surveillance for TDR will be important in understanding the full impact of new antiretroviral medications

Combining motion analysis and microfluidics--a novel approach for detecting whole-animal responses to test substances.

Small, early life stages, such as zebrafish embryos are increasingly used to assess the biological effects of chemical compounds in vivo. However, behavioural screens of such organisms are challenging in terms of both data collection (culture techniques, drug delivery and imaging) and data evaluation (very large data sets), restricting the use of high throughput systems compared to in vitro assays. Here, we combine the use of a microfluidic flow-through culture system, or BioWell plate, with a novel motion analysis technique, (sparse optic flow - SOF) followed by spectral analysis (discrete Fourier transformation - DFT), as a first step towards automating data extraction and analysis for such screenings. Replicate zebrafish embryos housed in a BioWell plate within a custom-built imaging system were subject to a chemical exposure (1.5% ethanol). Embryo movement was videoed before (30 min), during (60 min) and after (60 min) exposure and SOF was then used to extract data on movement (angles of rotation and angular changes to the centre of mass of embryos). DFT was subsequently used to quantify the movement patterns exhibited during these periods and Multidimensional Scaling and ANOSIM were used to test for differences. Motion analysis revealed that zebrafish had significantly altered movements during both the second half of the alcohol exposure period and also the second half of the recovery period compared to their pre-treatment movements. Manual quantification of tail flicking revealed the same differences between exposure-periods as detected using the automated approach. However, the automated approach also incorporates other movements visible in the organism such as blood flow and heart beat, and has greater power to discern environmentally-driven changes in the behaviour and physiology of organisms. We suggest that combining these technologies could provide a highly efficient, high throughput assay, for assessing whole embryo responses to various drugs and chemicals

Mechanisms of viral entry: sneaking in the front door

Recent developments in methods to study virus internalisation are providing clearer insights into mechanisms used by viruses to enter host cells. The use of dominant negative constructs, specific inhibitory drugs and RNAi to selectively prevent entry through particular pathways has provided evidence for the clathrin-mediated entry of hepatitis C virus (HCV) as well as the caveolar entry of Simian Virus 40. Moreover, the ability to image and track fluorescent-labelled virus particles in real-time has begun to challenge the classical plasma membrane entry mechanisms described for poliovirus and human immunodeficiency virus. This review will cover both well-documented entry mechanisms as well as more recent discoveries in the entry pathways of enveloped and non-enveloped viruses. This will include viruses which enter the cytosol directly at the plasma membrane and those which enter via endocytosis and traversal of internal membrane barrier(s). Recent developments in imaging and inhibition of entry pathways have provided insights into the ill-defined entry mechanism of HCV, bringing it to the forefront of viral entry research. Finally, as high-affinity receptors often define viral internalisation pathways, and tropism in vivo, host membrane proteins to which viral particles specifically bind will be discussed throughout

Heel raises versus prefabricated orthoses in the treatment of posterior heel pain associated with calcaneal apophysitis (Sever's Disease): study protocol for a randomised controlled trial

<p>Abstract</p> <p>Background</p> <p>Posterior Heel pain can present in children of 8 to 14 years, associated with or clinically diagnosed as Sever's disease, or calcaneal apophysitis. Presently, there are no comparative randomised studies evaluating treatment options for posterior heel pain in children with the clinical diagnosis of calcaneal apophysitis or Sever's disease. This study seeks to compare the clinical efficacy of some currently employed treatment options for the relief of disability and pain associated with posterior heel pain in children.</p> <p>Method</p> <p>Design: Factorial 2 × 2 randomised controlled trial with monthly follow-up for 3 months.</p> <p>Participants: Children with clinically diagnosed posterior heel pain possibly associated with calcaneal apophysitis/Sever's disease (n = 124).</p> <p>Interventions: Treatment factor 1 will be two types of shoe orthoses: a heel raise or prefabricated orthoses. Both of these interventions are widely available, mutually exclusive treatment approaches that are relatively low in cost. Treatment factor 2 will be a footwear prescription/replacement intervention involving a shoe with a firm heel counter, dual density EVA midsole and rear foot control. The alternate condition in this factor is no footwear prescription/replacement, with the participant wearing their current footwear.</p> <p>Outcomes: Oxford Foot and Ankle Questionnaire and the Faces pain scale.</p> <p>Discussion</p> <p>This will be a randomised trial to compare the efficacy of various treatment options for posterior heel pain in children that may be associated with calcaneal apophysitis also known as Sever's disease.</p> <p>Trial Registration</p> <p>Trial Number: ACTRN12609000696291</p> <p>Ethics Approval Southern Health: HREC Ref: 09271B</p