Directional emission of light from a nano-optical Yagi-Uda antenna

The plasmon resonance of metal nanoparticles can enhance and direct light from optical emitters in much the same way that radio frequency (RF) antennas enhance and direct the emission from electrical circuits. In the RF regime, a typical antenna design for high directivity is the Yagi-Uda antenna, which basically consists of a one-dimensional array of antenna elements driven by a single feed element. Here, we present the experimental demonstration of directional light emission from a nano-optical Yagi-Uda antenna composed of an array of appropriately tuned gold nanorods. Our results indicate that nano-optical antenna arrays are a simple but efficient tool for the spatial control of light emission.Comment: 4 pages, including 4 figure

Transcriptome bioinformatic analysis identifies potential therapeutic mechanism of pentylenetetrazole in down syndrome

<p>Abstract</p> <p>Background</p> <p>Pentylenetetrazole (PTZ) has recently been found to ameliorate cognitive impairment in rodent models of Down syndrome (DS). The mechanism underlying PTZ's therapeutic effect in DS is however not clear. Microarray profiling has previously reported differential expression, both up- and down-regulation, of genes in DS. Given this, transcriptomic data related to PTZ treatment, if available, could be used to understand the drug's therapeutic mechanism in DS. No such mammalian data however exists. Nevertheless, a <it>Drosophila </it>model inspired by PTZ induced kindling plasticity in rodents has recently been described. Microarray profiling has shown PTZ's downregulatory effect on gene expression in the fly heads.</p> <p>Methods</p> <p>In a comparative transcriptomics approach, I have analyzed the available microarray data in order to identify potential therapeutic mechanism of PTZ in DS. In the analysis, summary data of up- and down-regulated genes reported in human DS studies and of down-regulated genes reported in the <it>Drosophila </it>model has been used.</p> <p>Results</p> <p>I find that transcriptomic correlate of chronic PTZ in <it>Drosophila </it>counteracts that of DS. Genes downregulated by PTZ significantly over-represent genes upregulated in DS and under-represent genes downregulated in DS. Further, the genes which are common in the downregulated and upregulated DS set show enrichment for MAP kinase pathway.</p> <p>Conclusion</p> <p>My analysis suggests that downregulation of MAP kinase pathway may mediate therapeutic effect of PTZ in DS. Existing evidence implicating MAP kinase pathway in DS supports this observation.</p

Channel gain for a wrist-to-arm scenario in the 55-65 GHz frequency band

Wireless communication on the body is expected to become more important in the future. This communication will in certain scenarios benefit from higher frequencies of operation and their associated smaller antennas and potentially higher bandwidths. One of these scenarios is communication between a wristband and wearable sensors on the arm. In order to investigate the feasibility of such a scenario, propagation at 55â65 GHz along the arm is measured for two configurations. First, for increasing separation distances along the arm, and second for a transmitter is rotationally placed around the wrist. Two channel gain models are fitted to the data and used to obtain a channel gain exponent in the first configuration and loss per angle of rotation in the second configuration. These models are relevant inputs for the design of future wearable wireless systems

The secretome of alginate-encapsulated limbal epithelial stem cells modulates corneal epithelial cell proliferation

Limbal epithelial stem cells may ameliorate limbal stem cell deficiency through secretion of therapeutic proteins, delivered to the cornea in a controlled manner using hydrogels. In the present study the secretome of alginate-encapsulated limbal epithelial stem cells is investigated. Conditioned medium was generated from limbal epithelial stem cells encapsulated in 1.2% (w/v) calcium alginate gels. Conditioned medium proteins separated by 1-D gel electrophoresis were visualized by silver staining. Proteins of interest including secreted protein acidic and rich in cysteine, profilin-1, and galectin-1 were identified by immunoblotting. The effect of conditioned medium (from alginate-encapsulated limbal epithelial stem cells) on corneal epithelial cell proliferation was quantified and shown to significantly inhibit (P</=0.05) their growth. As secreted protein acidic and rich in cysteine was previously reported to attenuate proliferation of epithelial cells, this protein may be responsible, at least in part, for inhibition of corneal epithelial cell proliferation. We conclude that limbal epithelial stem cells encapsulated in alginate gels may regulate corneal epithelialisation through secretion of inhibitory proteins

Genome-Wide Binding Map of the HIV-1 Tat Protein to the Human Genome

The HIV-1 Trans-Activator of Transcription (Tat) protein binds to multiple host cellular factors and greatly enhances the level of transcription of the HIV genome. While Tat's control of viral transcription is well-studied, much less is known about the interaction of Tat with the human genome. Here, we report the genome-wide binding map of Tat to the human genome in Jurkat T cells using chromatin immunoprecipitation combined with next-generation sequencing. Surprisingly, we found that ∼53% of the Tat target regions are within DNA repeat elements, greater than half of which are Alu sequences. The remaining target regions are located in introns and distal intergenic regions; only ∼7% of Tat-bound regions are near transcription start sites (TSS) at gene promoters. Interestingly, Tat binds to promoters of genes that, in Jurkat cells, are bound by the ETS1 transcription factor, the CBP histone acetyltransferase and/or are enriched for histone H3 lysine 4 tri-methylation (H3K4me3) and H3K27me3. Tat binding is associated with genes enriched with functions in T cell biology and immune response. Our data reveal that Tat's interaction with the host genome is more extensive than previously thought, with potentially important implications for the viral life cycle

A review of elliptical and disc galaxy structure, and modern scaling laws

A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their models to describe the radial distribution of stars in `nebulae'. This article reviews the progress since then, providing both an historical perspective and a contemporary review of the stellar structure of bulges, discs and elliptical galaxies. The quantification of galaxy nuclei, such as central mass deficits and excess nuclear light, plus the structure of dark matter halos and cD galaxy envelopes, are discussed. Issues pertaining to spiral galaxies including dust, bulge-to-disc ratios, bulgeless galaxies, bars and the identification of pseudobulges are also reviewed. An array of modern scaling relations involving sizes, luminosities, surface brightnesses and stellar concentrations are presented, many of which are shown to be curved. These 'redshift zero' relations not only quantify the behavior and nature of galaxies in the Universe today, but are the modern benchmark for evolutionary studies of galaxies, whether based on observations, N-body-simulations or semi-analytical modelling. For example, it is shown that some of the recently discovered compact elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to appear in "Planets, Stars and Stellar Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references incl. many somewhat forgotten, pioneer papers. Original submission to Springer: 07-June-201

Change in physical activity level and clinical outcomes in older adults with knee pain: a secondary analysis from a randomised controlled trial

BACKGROUND: Exercise interventions improve clinical outcomes of pain and function in adults with knee pain due to osteoarthritis and higher levels of physical activity are associated with lower severity of pain and higher levels of physical functioning in older adults with knee osteoarthritis in cross-sectional studies. However, to date no studies have investigated if change in physical activity level during exercise interventions can explain clinical outcomes of pain and function. This study aimed to investigate if change in physical activity during exercise interventions is associated with future pain and physical function in older adults with knee pain. METHODS: Secondary longitudinal data analyses of a three armed exercise intervention randomised controlled trial. Participants were adults with knee pain attributed to osteoarthritis, over the age of 45 years old (n = 514) from Primary Care Services in the Midlands and Northwest regions of England. Crude and adjusted associations between absolute change in physical activity from baseline to 3 months (measured by the self-report Physical Activity Scale for the Elderly (PASE)) and i) pain ii) physical function (Western Ontario and McMaster Universities Osteoarthritis Index) and iii) treatment response (OMERACT-OARSI responder criteria) at 3 and 6 months follow-up were investigated using linear and logistic regression. RESULTS: Change in physical activity level was not associated with future pain, function or treatment response outcomes in crude or adjusted models at 3 or 6 months (P > 0.05). A 10 point increase in PASE was not associated with pain β = - 0.01 (- 0.05, 0.02), physical function β = - 0.09 (- 0.19, 0.02) or likelihood (odds ratio) of treatment response 1.02 (0.99, 1.04) at 3 months adjusting for sociodemographics, clinical covariates and the trial intervention arm. Findings were similar for 6 month outcome models. CONCLUSIONS: Change in physical activity did not explain future clinical outcomes of pain and function in this study. Other factors may be responsible for clinical improvements following exercise interventions. However, the PASE may not be sufficiently responsive to measure change in physical activity level. We also recommend further investigation into the responsiveness of commonly used physical activity measures. TRIAL REGISTRATION: ( ISRCTN93634563 ). Registered 29th September 2011