Regulation of the cardiomyocyte transcriptome vs translatome by endothelin-1 and insulin: translational regulation of 5' terminal oligopyrimidine tract (TOP) mRNAs by insulin

Background: Changes in cellular phenotype result from underlying changes in mRNA transcription and translation. Endothelin-1 stimulates cardiomyocyte hypertrophy with associated changes in mRNA/protein expression and an increase in the rate of protein synthesis. Insulin also increases the rate of translation but does not promote overt cardiomyocyte hypertrophy. One mechanism of translational regulation is through 5' terminal oligopyrimidine tracts (TOPs) that, in response to growth stimuli, promote mRNA recruitment to polysomes for increased translation. TOP mRNAs include those encoding ribosomal proteins, but the full panoply remains to be established. Here, we used microarrays to compare the effects of endothelin-1 and insulin on the global transcriptome of neonatal rat cardiomyocytes, and on mRNA recruitment to polysomes (i.e. the translatome). Results: Globally, endothelin-1 and insulin (1 h) promoted >1.5-fold significant (false discovery rate 1.25-fold significant changes in expression in total and/or polysomal RNA induced by endothelin-1 or insulin, respectively, of which ~35% of endothelin-1-responsive and ~56% of insulin-responsive transcripts were translationally regulated. Of mRNAs for established proteins recruited to polysomes in response to insulin, 49 were known TOP mRNAs with a further 15 probable/possible TOP mRNAs, but 49 had no identifiable TOP sequences or other consistent features in the 5' untranslated region. Conclusions: Endothelin-1, rather than insulin, substantially affects global transcript expression to promote cardiomyocyte hypertrophy. Effects on RNA recruitment to polysomes are subtle, with differential effects of endothelin-1 and insulin on specific transcripts. Furthermore, although insulin promotes recruitment of TOP mRNAs to cardiomyocyte polysomes, not all recruited mRNAs are TOP mRNAs

Defects in GaN Nanowires

High resolution and cross-sectional transmission electron microscopy (HRTEM, XTEM) were used to characterize common defects in wurtzite GaN nanowires grown via the vapor-liquid-solid (VLS) mechanism. High resolution transmission electron microscopy showed that these nanowires contained numerous (001) stacking defects interspersed with cubic intergrowths. Using cross-sectional transmission electron microscopy, bicrystalline nanowires were discovered with two-fold rotational twin axes along their growth directions, and were concluded to grow along high index directions or vicinal to low index planes. A defect-mediated VLS growth model was used to account for the prevalence of these extended defects. Implications for nanowire growth kinetics and device behavior are discussed

Effect of the polar surface on GaN nanostructure growth and morphology

Wurtzite gallium nitride nanostructures were grown by thermal reaction of gallium oxide and ammonia. The resulting morphology varied depending on ammonia flow rate. At 75 sccm only nanowires were obtained, while polyhedral crystals and nanobelts were observed at 175 sccm. Scanning electron microscopy and transmission electron microscopy revealed both thin smooth and thick corrugated nanowires. The growth axes of most of the smooth ones, as well as the nanobelts, were perpendicular to the c-axis (\u3c0001\u3e), while the corrugated nanowires and the large polyhedra grew parallel to \u3c0001\u3e. We propose a model to explain these morphology variations in terms of the Ga/N ratio and the different characteristic lengths of {0001} polar surfaces in the different nanostructures

Self-branching in GaN Nanowires Induced by a Novel Vapor-Liquid-Solid Mechanism

Nanowires have great potential as building blocks for nanoscale electrical and optoelectronic devices. The difficulty in achieving functional and hierarchical nanowire structures poses an obstacle to realization of practical applications. While post-growth techniques such as fluidic alignment might be one solution, self-assembled structures during growth such as branches are promising for functional nanowire junction formation. In this study, we report vapor-liquid-solid (VLS) self-branching of GaN nanowires during AuPd-catalyzed chemical vapor deposition (CVD). This is distinct from branches grown by sequential catalyst seeding or vapor-solid (VS) mode. We present evidence for a VLS growth mechanism of GaN nanowires different from the well-established VLS growth of elemental wires. Here, Ga solubility in AuPd catalyst is limitless as suggested by a hypothetical pseudo-binary phase diagram, and the direct reaction between NH3 vapor and Ga in the liquid catalyst induce the nucleation and growth. The self-branching can be explained in the context of the proposed VLS scheme and migration of Ga-enriched AuPd liquid on Ga-stabilized polar surface of mother nanowires. This work is supported by DOE Grant No. DE-FG02-98ER45701

Identifying Cross-Sided Liquidity Externalities

__Abstract__ We study the relevance of the cross-sided externality between liquidity makers and takers from the two-sided market perspective. We use exogenous changes in the make/take fee structure, minimum tick-size and technological shocks for liquidity takers and makers, as experiments to identify cross-sided complementarities between liquidity makers and takers in the U.S. equity market. We find that the externality is on average positive, but it decreases with adverse selection. We quantify the economic significance of the externality by evaluating an exchange's revenue after a make/take fee change

Sunshine Trading: Flashes of Trading Intent at the NASDAQ

We use the introduction and the subsequent removal of the flash order facility (an actionable indication of interest, IOI) from the NASDAQ as a natural experiment to investigate the impact of voluntary disclosure of trading intent on market quality. We find that flash orders significantly improve liquidity in the NASDAQ. In addition, overall market quality improves substantially when the flash functionality is introduced and deteriorates when it is removed. One explanation for our findings is that flash orders are placed by less informed traders and fulfill their role as an advertisement of uninformed liquidity needs. They successfully attract responses from liquidity providers immediately after the announcement is placed, thus lowering the risk-bearing cost for the overall market. Our study is important in understanding the impact of voluntary disclosure, in guiding future market design choices, and in the current debate on dark pools and IOIs

Aggregate Stock Market Illiquidity and Bond Risk Premia

We assess the effect of aggregate stock market illiquidity on U.S. Treasury bond risk premia. We find that the stock market illiquidity variable adds to the well established Cochrane-Piazzesi and Ludvigson-Ng factors. It explains 10%, 9%, 7%, and 7% of the one-year-ahead variation in the excess return for two-, three-, four-, and ve-year bonds respectively and increases the adjusted R2 by 3-6% across all maturities over Cochrane and Piazzesi (2005) and Ludvigson and Ng (2009) factors. The effects are highly statistically and economically significant both in and out of sample. We find that our result is robust to and is not driven by information from open interest in the futures market, long-run inflation expectations, dispersion in beliefs, and funding liquidity. We argue that stock market illiquidity is a timely variable that is related to " right-to-quality" episodes and might contain information about expected future business conditions through funding liquidity and investment channels

Systematic study of contact annealing: Ambipolar silicon nanowire transistor with improved performance

High performance ambipolar silicon nanowire (SiNW) transistors were fabricated. SiNWs with uniform oxide sheath thicknesses of 6–7 nm were synthesized via a gas-flow-controlled thermal evaporation method. Field effect transistors (FETs) were fabricated using as-grown SiNWs. A two step annealing process was used to control contacts between SiNW and metal source and drain in order to enhance device performance. Initially ρ-channel devices exhibited ambipolar behavior after contact annealing at 400 ºC. Significant increases in on/off ratio and channel mobility were also achieved by annealing

Synthesis and Post-growth Doping of Silicon Nanowires

High quality silicon nanowires (SiNWs) were synthesized via a thermal evaporation method without the use of catalysts. Scanning electron microscopy and transmission electron microscopy showed that SiNWs were long and straight crystalline silicon with an oxide sheath. Field effect transistors (FETs) were fabricated to investigate the electrical transport properties. Devices on as-grown material were p-channel with channel mobilities 1 - 10 cm2 V-1 s-1. Post-growth vapor doping with bismuth converted these to n-channel behavior

Preliminary Analysis of the Feasibility and Effectiveness of Whole Body Vibration as a Therapeutic Intervention in a Skilled Nursing Facility

Skeletal muscle sarcopenia results in loss of strength, power and functional capabilities leading to decreased independence and an increased reliance on the healthcare system. Exercise is an effective countermeasure to age related loss of muscle, but may be difficult in elderly patients with complex functional limitations. Whole body vibration (WBV) is a novel tool used to stimulate the neuromuscular system; research indicates it may improve strength, power, and balance in many populations. Purpose: The purposes of this study were to determine if WBV training is feasible in a skilled nursing facility and if standard of care (SOC) with augmented WBV training improves physical function in patients compared to SOC alone. Methods: A prospective cohort design was used to accomplish the study objectives. Twelve patients (10 females; 2 males) who were residents at a skilled nursing facility consented to the study protocol and were divided into two groups. Group 1 (CON; 73.8 ± 5.7 y; 165.0 ± 0.03 cm; 77.5 ± 11.6kg) underwent SOC therapy intervention including progressive balance, strength, and range of motion exercises. Group 2 (VIB; 74.1 ± 2.3y; 169.0 ± 0.04cm; 70.5 ± 4.3kg) underwent a similar physical therapy intervention but also completed progressive WBV treatment on a symmetrically vibrating plate (2mm; 25-35 Hz). Patients completed clinical tests of physical function before and after the 23 ± 2.3 day intervention. Physical function tests included timed up-and-go (TUG) tests from a 40cm chair and a Berg balance assessment (BBA). Additionally, manual muscle tests were completed using a hand-held dynamometer for hip flexion (HF), hip abduction (HA), knee extension (KE), knee flexion (KF), plantar flexion (PF), and dorsi-flexion (DF). Student’s t-tests were used to compare the difference scores pre- and post-intervention; alpha was set at p\u3c0.05 to determine statistical significance. Results: No adverse effects were documented in either group throughout the study. Mean physical function improved in all tested variables for both groups. However, no between group differences (CON vs. VIB) were observed in BBA (p=0.52), TUG (p=0.07), HF (p=0.80), HA (p=0.47), KE (p=0.73), KF (p=0.97), PF (p=0.59), and DF (p=0.83). Conclusions: Use of WBV as an adjunct exercise intervention in a skilled nursing facility was feasible and safe in this small sample. Although no between group differences were evident, a larger sample is needed to definitively accept or reject the hypothesis. Moreover, systematic research is needed to develop precise protocols to effectively and efficiently utilize WBV in hospitalized elders