Cassini's floating potential in Titan's ionosphere: 3-D particle-in-cell simulations

Accurate determination of Cassini’s spacecraft potential in Titan’s ionosphere is important for interpreting measurements by its low energy plasma instruments. Estimates of the floating potential varied significantly, however, between the various different plasma instruments. In this study we utilize 3-D particle-in-cell simulations to understand the key features of Cassini’s plasma interaction in Titan’s ionosphere. The spacecraft is observed to charge to negative potentials for all scenarios considered, and close agreement is found between the current onto the simulated Langmuir Probe and that observed in Titan’s ionosphere. These simulations are therefore shown to provide a viable technique for modeling spacecraft interacting with Titan’s dusty ionosphere

Production of a Higgs pseudoscalar plus two jets in hadronic collisions

We consider the production of a Higgs pseudoscalar accompanied by two jets in hadronic collisions. We work in the limit that the top quark is much heavier than the Higgs pseudoscalar and use an effective Lagrangian for the interactions of gluons with the pseudoscalar. We compute the amplitudes involving: 1) four gluons and the pseudoscalar, 2) two quarks, two gluons and the pseudoscalar and 3) four quarks and the pseudoscalar. We find that the pseudoscalar amplitudes are nearly identical to those for the scalar case, the only differences being the overall size and the relative signs between terms. We present numerical cross sections for proton-proton collisions with center-of-mass energy 14 TeV.Comment: 12 pages, LaTeX, 4 Postscript figures, submitted to Phys. Rev.

Combined Endocyclophotocoagulation and Phacoemulsification in Patients with Glaucoma of African Descent

The aim of this study was to evaluate the outcomes of combined endocyclophotocoagulation (ECP) and phacoemulsification regarding vision, refraction, intraocular pressure (IOP), medication dependence, and complications in patients of African descent. A retrospective chart review was performed including all cases of ECP combined with phacoemulsification from October 2015 to March 2017. Exclusion criteria consisted of patients who were not of African descent and patients with <1 month follow-up. IOP was the primary outcome. Thirty-two eyes of 29 patients were included in the study. Mean ± standard deviation (SD) of IOP decreased from 17.30 ± 6.30 mmHg preoperatively to 15.88 ± 4.23 mmHg at the last postoperative visit (P = 0.301). In 2 of eight patients who did not demonstrate a difference in pre- and postoperative IOP changes, all IOP lowering medications were stopped. The mean ± SD of follow-up was 5.05 ± 4.08 months with a range of 1 to 18 months. The mean ± SD number of medications used for each patient for IOP control decreased from 2.59 ± 1.01 preoperatively to 1.97 ±1.38 (P = 0.045). Average visual acuity improved from 20/50 preoperatively to 20/25 (P = 0.002). Postoperative complication rate was low. ECP combined with phacoemulsification was effective to decrease IOP lowering medication dependence in patients of African descent. We found that combined ECP and phacoemulsification can lead to a significantly decreased dependence on IOP lowering drops, with some patients demonstrating complete independence from drops following surgery. Although there was not a significant decrease in IOP postoperatively when analyzed collectively, larger studies might to find such an association. Combined ECP and phacoemulsification has been shown to be a safe combination in patients with refractive glaucoma and may be considered if a patient desire less dependence on IOP lowering drops once other first-line methods have failed, or as a bridge between conservative and more definitive surgical treatment. Epub: October 1, 201

Challenging empowerment: AIDS-affected southern African children and the need for a multi-level relational approach

Critics of empowerment have highlighted the concept's mutability, focus on individual transformation, one-dimensionality and challenges of operationalisation. Relating these critiques to children's empowerment raises new challenges. Drawing on scholarship on children's subjecthood and exercise of power, alongside empirical research with children affected by AIDS, I argue that empowerment envisaged as individual self-transformation and increased capacity to act independently offers little basis for progressive change. Rather it is essential to adopt a relational approach that recognises the need to transform power relationships at multiple levels. This analysis has implications for our wider understanding of empowerment in the 21st century. © The Author(s) 2013.This research was funded by DFID

Can empirical biplots predict high entropy oxide phases?

High entropy oxides are entropy-stabilised oxides that adopt specific disordered structures due to entropy stabilisation. They are a new class of materials that utilises the high-entropy concept first discovered in metallic alloys. They can have interesting properties due to the interactions at the electronic level and can be combined with other materials to make composite structures. The design of new meta-materials that utilise this concept to solve real-world problems may be a possibility but further understanding of how their phase stabilisation is required. In this work, biplots of the composition’s mean electronegativity are plotted against the electron-per-atom ratio of the compounds. The test dataset accuracy in the resulting biplots improves from 78% to 100% when using atomic-number-per-atom Z/a ratios as a biplot parameter. Phase stability maps were constructed using a Voronoi tessellation. This can be of use in determining stability at composite material interfaces

Extracellular Sodium Interacts with the HERG Channel at an Outer Pore Site

Most voltage-gated K+ currents are relatively insensitive to extracellular Na+ (Na+o), but Na+o potently inhibits outward human ether-a-go-go–related gene (HERG)–encoded K+ channel current (Numaguchi, H., J.P. Johnson, Jr., C.I. Petersen, and J.R. Balser. 2000. Nat. Neurosci. 3:429–30). We studied wild-type (WT) and mutant HERG currents and used two strategic probes, intracellular Na+ (Na+i) and extracellular Ba2+ (Ba2+o), to define a site where Na+o interacts with HERG. Currents were recorded from transfected Chinese hamster ovary (CHO-K1) cells using the whole-cell voltage clamp technique. Inhibition of WT HERG by Na+o was not strongly dependent on the voltage during activating pulses. Three point mutants in the P-loop region (S624A, S624T, S631A) with intact K+ selectivity and impaired inactivation each had reduced sensitivity to inhibition by Na+o. Quantitatively similar effects of Na+i to inhibit HERG current were seen in the WT and S624A channels. As S624A has impaired Na+o sensitivity, this result suggested that Na+o and Na+i act at different sites. Extracellular Ba2+ (Ba2+o) blocks K+ channel pores, and thereby serves as a useful probe of K+ channel structure. HERG channel inactivation promotes relief of Ba2+ block (Weerapura, M., S. Nattel, M. Courtemanche, D. Doern, N. Ethier, and T. Hebert. 2000. J. Physiol. 526:265–278). We used this feature of HERG inactivation to distinguish between simple allosteric and pore-occluding models of Na+o action. A remote allosteric model predicts that Na+o will speed relief of Ba2+o block by promoting inactivation. Instead, Na+o slowed Ba2+ egress and Ba2+ relieved Na+o inhibition, consistent with Na+o binding to an outer pore site. The apparent affinities of the outer pore for Na+o and K+o as measured by slowing of Ba2+ egress were compatible with competition between the two ions for the channel pore in their physiological concentration ranges. We also examined the role of the HERG closed state in Na+o inhibition. Na+o inhibition was inversely related to pulsing frequency in the WT channel, but not in the pore mutant S624A

Real Time Wireless Air Pollution Monitoring system

Air pollution has significant influence on the concentration of constituents in the atmosphere leading to effects like global warming and acid rains. To avoid such adverse imbalances in the nature, an air pollution monitoring system is utmost important. This paper attempts to develop an effective solution for pollution monitoring using wireless sensor networks (WSN) on a real time basis namely real time wireless air pollution monitoring system. Commercially available discrete gas sensors for sensing concentration of gases l ike CO 2 , NO 2, CO and O 2 are calibrated using appropriate calibration technologies. These pre - calibrated gas sensors are then integrated with the wireless sensor motes for field deployment at the campus and the Hyderabad city using multi hop data aggregatio n algorithm. A light weight middleware and a web interface to view the live pollution data in the form of numbers and charts from the test beds was developed and made available from anywhere on the internet. Other parameters like temperature and humidity w ere also sensed along with gas concentrations to enable data analysis through data fusion techniques. Experimentation carried out using the developed wireless air pollution monitoring system under different physical conditions show that the system collects reliable source of real time fine - grain pollution data

Saturation in cascaded optical amplifier free-space optical communication systems

The performance of a free-space optical (FSO) communication system in a turbulent atmosphere employing an optical amplifier (OA) cascade to extend reach is investigated. Analysis of both single and cascaded OA FSO communication links is given and the implications of using both adaptive (to channel state) and non-adaptive decision threshold schemes are analysed. The benefits of amplifier saturation, for example in the form of effective scintillation reduction when a non-adaptive decision threshold scheme is utilised at the receiver for different atmospheric turbulence regimes, are presented. Monte Carlo simulation techniques are used to model the probability distributions of the optical signal power, noise and the average bit error rate due to scintillation for the cascade. The performance of an adaptive decision threshold is superior to a non-adaptive decision threshold for both saturated and fixed gain preamplified receivers and the ability of a saturated gain OA to suppress scintillation is only meaningful for system performance when a non-adaptive decision threshold is used at the receiver. An OA cascade can be successfully used to extend reach in FSO communication systems and specific system implementations are presented. The optimal cascade scheme with a non-adaptive receiver would use frequent low gain saturated amplification

Four Zero Texture Fermion Mass Matrices in SO(10) GUT

We attempt the integration of the phenomenologically successful four zero texture of fermion mass matrices with the renormalizable SO(10) GUT. The resulting scenario is found to be highly predictive. Firstly, we examine the phenomenological implications of a class of the lepton mass matrices with parallel texture structures and obtain interesting constraints on the parameters of the charged lepton and the neutrino mass matrices. We combine these phenomenological constraints with the constraints obtained from SO(10) GUT to reduce the number of the free parameters and to further constrain the allowed ranges of the free parameters. The solar/atmospheric mixing angles obtained in this analysis are in fairly good agreement with the data.Comment: 14 pages, 3 figures, 1 tabl