489 research outputs found
Ti-TiOx-Pt Metal-Oxide-Metal Diodes Fabricated via a Simple Oxidation Technique
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
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Alternative dosing guidelines to improve outcomes in childhood tuberculosis : a mathematical modelling study
Background
Malnourished and young children are particularly susceptible to severe forms of tuberculosis and poor treatment response. WHO dosing guidelines for drugs for tuberculosis treatment are based only on weight, which might lead to systematic underdosing and poor outcomes in these children. We aimed to assess and quantify the population effect of WHO guidelines for drug-susceptible tuberculosis in children in the 20 countries with the highest disease burden.
Methods
We used an integrated model that linked country-specific demographic data at the individual level from the 20 countries with the highest disease burden to pharmacokinetic, outcome, and epidemiological models. We estimated tuberculosis treatment outcomes in children younger than 5 years following WHO guidelines (children are dosed by weight bands corresponding to the number of fixed-dose combination tablets [75 mg rifampicin, 50 mg isoniazid, 150 mg pyrazinamide]) and two alternative dosing strategies: one based on a proposed algorithm that uses age, weight, and available formulations, in which underweight children would receive the same drug doses as would normal weight children of the same age; and another based on an individualised algorithm without dose limitations, in which derived doses results in target exposure attainment for the typical child.
Findings
We estimated that 57 234 (43%) of 133 302 children younger than 5 years who were treated for tuberculosis in 2017 were underdosed with WHO dosing and only 47% of children would reach the rifampicin exposure target. Underdosing and subtherapeutic exposures were more common among malnourished children than among age-matched healthy children. The proposed dosing approach improved estimated rifampicin target exposure attainment to 62% and equalised outcomes by nutritional status. An estimated third of unfavourable treatment outcomes might be resolved with this dosing strategy, saving the lives of a minimum of 2423 children in these countries annually. With individualised dosing approaches, almost all children could achieve adequate exposure for cure.
Interpretation
This work shows that a simple change in dosing procedure to include age and nutritional status, requiring no additional measurements or new drug formulations, is one approach to improve tuberculosis treatment outcomes in children, especially malnourished children who are at high risk of mortality
When push comes to shove - RNA polymerase and DNA-bound protein roadblocks
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
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
We consider a Bose-Einstein condensate (BEC) of 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
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
We study the Bose-Einstein condensation for a cloud of Li 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
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
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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