489 research outputs found

    Ti-TiOx-Pt Metal-Oxide-Metal Diodes Fabricated via a Simple Oxidation Technique

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    This work presents the successful production, via a simple oxidation process, of Ti-TiOx-Pt Metal-Oxide-Metal diodes with excellent electrical asymmetry. TEM analysis has been used to verify the oxide thickness. A thicker layer produces better diodes, although they are of a less uniform nature. The conduction mechanism in these diodes is still under investigation

    When push comes to shove - RNA polymerase and DNA-bound protein roadblocks

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    In recent years, transcriptional roadblocking has emerged as a crucial regulatory mechanism in gene expression, whereby other DNA-bound obstacles can block the progression of transcribing RNA polymerase (RNAP), leading to RNAP pausing and ultimately dissociation from the DNA template. In this review, we discuss the mechanisms by which transcriptional roadblocks can impede RNAP progression, as well as how RNAP can overcome these obstacles to continue transcription. We examine different DNA-binding proteins involved in transcriptional roadblocking and their biophysical properties that determine their effectiveness in blocking RNAP progression. The catalytically dead CRISPR-Cas (dCas) protein is used as an example of an engineered programmable roadblock, and the current literature in understanding the polarity of dCas roadblocking is also discussed. Finally, we delve into a stochastic model of transcriptional roadblocking and highlight the importance of transcription factor binding kinetics and its resistance to dislodgement by an elongating RNAP in determining the strength of a roadblock.Nan Hao, Alana J. Donnelly, Ian B. Dodd, Keith E. Shearwi

    Effect of metformin in addition to an antenatal diet and lifestyle intervention on fetal growth and adiposity: the GRoW randomised trial

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    Background: The infants born to women who are overweight or obese in pregnancy are at an increased risk of being born macrosomic or large for gestational age. Antenatal dietary and lifestyle interventions have been shown to be ineffective at reducing this risk. Our aim was to examine the effects of metformin in addition to a diet and lifestyle intervention on fetal growth and adiposity among women with a BMI above the healthy range. Methods: Women who had a body mass index ≥25 kg/m² in early pregnancy, and a singleton gestation, were enrolled in the GRoW trial from three public maternity hospitals in metropolitan Adelaide. Women were invited to have a research ultrasounds at 28 and 36 weeks' gestation at which ultrasound measures of fetal biometry and adiposity were obtained. Fetal biometry z-scores and trajectories were calculated. Measurements and calculations were compared between treatment groups. This secondary analysis was pre-specified. Results: Ultrasound data from 511 women were included in this analysis. The difference in femur length at 36 weeks' gestation was (0.07 cm, 95% CI 0.01-0.14 cm, p = 0.019) and this was was statistically significant, however the magnitude of effect was small. Differences between treatment groups for all other fetal biometry measures, z-scores, estimated fetal weight, and adiposity measures at 28 and 36 weeks' gestation were similar. Conclusions: The addition of metformin to dietary and lifestyle advice in pregnancy for overweight and obese women has no clinically relevant effect on ultrasound measures of fetal biometry or adiposity.Amanda J. Poprzeczny, Jennie Louise, Andrea R. Deussen and Jodie M. Dod

    Bistability and macroscopic quantum coherence in a BEC of ^7Li

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    We consider a Bose-Einstein condensate (BEC) of 7Li^7Li in a situation where the density undergoes a symmetry breaking in real space. This occurs for a suitable number of condensed atoms in a double well potential, obtained by adding a standing wave light field to the trap potential. Evidence of bistability results from the solution of the Gross-Pitaevskii equation. By second quantization, we show that the classical bistable situation is in fact a Schr\"odinger cat (SC) and evaluate the tunneling rate between the two SC states. The oscillation between the two states is called MQC (macroscopic quantum coherence); we study the effects of losses on MQC.Comment: 8 pages, 11 figures. e-mail: [email protected]

    Skin and subcutaneous fascia closure at caesarean section to reduce wound complications: the closure randomised trial

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    Background: Wound infection is a common complication following caesarean section. Factors influencing the risk of infection may include the suture material for skin closure, and closure of the subcutaneous fascia. We assessed the effect of skin closure with absorbable versus non-absorbable suture, and closure versus non-closure of the subcutaneous fascia on risk of wound infection following Caesarean section. Methods: Women undergoing caesarean birth at an Adelaide maternity hospital were eligible for recruitment to a randomised trial using a 2 × 2 factorial design. Women were randomised to either closure or non-closure of the subcutaneous fascia and to subcuticular skin closure with an absorbable or non-absorbable suture. Participants were randomised to each of the two interventions into one of 4 possible groups: Group 1 - non-absorbable skin suture and non-closure of the subcutaneous fascia; Group 2 - absorbable skin suture and non-closure of the subcutaneous fascia; Group 3 - non-absorbable skin suture and closure of the subcutaneous fascia; and Group 4 - absorbable skin suture and closure of the subcutaneous fascia. The primary outcomes were reported wound infection and wound haematoma or seroma within the first 30 days after birth. Results: A total of 851 women were recruited and randomised, with 849 women included in the analyses (Group 1: 216 women; Group 2: 212 women; Group 3: 212 women; Group 4: 211 women). In women who underwent fascia closure, there was a statistically significant increase in risk of wound infection within 30 days post-operatively for those who had skin closure with an absorbable suture (Group 4), compared with women who had skin closure with a non-absorbable suture (Group 3) (adjusted RR 2.17; 95% CI 1.05, 4.45; p = 0.035). There was no significant difference in risk of wound infection for absorbable vs non-absorbable sutures in women who did not undergo fascia closure. Conclusion: The combination of subcutaneous fascia closure and skin closure with an absorbable suture may be associated with an increased risk of reported wound infection after caesarean section.Amanda J. Poprzeczny, Rosalie M. Grivell, Jennie Louise, Andrea R. Deussen and Jodie M. Dod

    Self-Trapping, Quantum Tunneling and Decay Rates for a Bose Gas with Attractive Nonlocal Interaction

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    We study the Bose-Einstein condensation for a cloud of 7^7Li atoms with attractive nonlocal (finite-range) interaction in a harmonic trap. In addition to the low-density metastable branch, that is present also in the case of local interaction, a new stable branch appears at higher densities. For a large number of atoms, the size of the cloud in the stable high-density branch is independent of the trap size and the atoms are in a macroscopic quantum self-trapped configuration. We analyze the macroscopic quantum tunneling between the low-density metastable branch and the high-density one by using the istanton technique. Moreover we consider the decay rate of the Bose condensate due to inelastic two- and three-body collisions.Comment: 5 pages, 4 figures, submitted to Phys. Rev.

    Non-equilibrium entangled steady state of two independent two-level systems

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    We determine and study the steady state of two independent two-level systems weakly coupled to a stationary non-equilibrium environment. Whereas this bipartite state is necessarily uncorrelated if the splitting energies of the two-level systems are different from each other, it can be entangled if they are equal. For identical two-level systems interacting with two bosonic heat baths at different temperatures, we discuss the influence of the baths temperatures and coupling parameters on their entanglement. Geometric properties, such as the baths dimensionalities and the distance between the two-level systems, are relevant. A regime is found where the steady state is a statistical mixture of the product ground state and of the entangled singlet state with respective weights 2/3 and 1/3

    Bosons in a Toroidal Trap: Ground State and Vortices

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    We study the Bose-Einstein condensate (BEC) in a 3-D toroidal Mexican hat trap. By changing the parameters of the potential, or the number of bosons, it is possible to modify strongly the density profile of the BEC. We consider the ground state properties for positive and negative scattering length and calculate the spectrum elementary excitations. We also discuss the macroscopic phase coherence and superfluidity of the BEC by analyzing vortex states and their stability.Comment: 15 pages + 4 figures, to be published in Phys. Rev.
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