CROSS SECTIONS FOR SCATTERING OF ELECTRONS ON BF3

We calculate cross sections for elastic scattering and electronic excitation of BF3 molecules by low energy electrons. The R-Matrix code Quantemol-N has been used for calculations. The cross sections indicate the presence of a shape resonance of symmetry B-1 (A(2)'' in D-3h) at around 4.5 eV

Estimation of atmospheric total organic carbon (TOC) – paving the path towards carbon budget closure

The atmosphere contains a rich variety of reactive organic compounds, including gaseous volatile organic carbon (VOCs), carbonaceous aerosols, and other organic compounds at varying volatility. Here we present a novel and simple approach to measure atmospheric non-methane total organic carbon (TOC) based on catalytic oxidation of organics in bulk air to carbon dioxide. This method shows little sensitivity towards humidity and near 100 % oxidation efficiencies for all VOCs tested. We estimate a best-case hourly precision of 8 ppb C during times of low ambient variability in carbon dioxide, methane, and carbon monoxide (CO). As proof of concept of this approach, we show measurements of TOC+CO during August–September 2016 from a coastal city in the southwest United Kingdom. TOC+CO was substantially elevated during the day on weekdays (occasionally over 2 ppm C) as a result of local anthropogenic activity. On weekends and holidays, with a mean (standard error) of 102 (8) ppb C, TOC+CO was lower and showed much less diurnal variability. TOC+CO was significantly lower when winds were coming off the Atlantic Ocean than when winds were coming off land if we exclude the weekday daytime. By subtracting the estimated CO from TOC+CO, we constrain the mean (uncertainty) TOC in Atlantic-dominated air masses to be around 23 ( ±≥8 ) ppb C during this period. A proton-transfer-reaction mass spectrometer (PTR-MS) was deployed at the same time, detecting a large range of organic compounds (oxygenated VOCs, biogenic VOCs, aromatics, dimethyl sulfide). The total speciated VOCs from the PTR-MS, denoted here as Sum(VOC), amounted to a mean (uncertainty) of 12 ( ±≤3 ) ppb C in marine air. Possible contributions from a number of known organic compounds present in marine air that were not detected by the PTR-MS are assessed within the context of the TOC budget. Finally, we note that the use of a short, heated sample tube can improve the transmission of organics to the analyzer, while operating our system alternately with and without a particle filter should enable a better separation of semi-volatile and particulate organics from the VOCs within the TOC budget. Future concurrent measurements of TOC, CO, and a more comprehensive range of speciated VOCs would enable a better characterization and understanding of the atmospheric organic carbon budget

Glucose-6-phosphate dehydrogenase deficiency; the single most important cause of neonatal hyperbilirubinaemia in Kano, Nigeria

Introduction: Glucose- 6-phosphate dehydrogenase deficiency is the most common enzymatic disorder of the red cell and an important risk factor for neonatal jaundice.Methodology: The aim of the study was to determine the incidence of G-6-PD deficiency among jaundiced neonates, and describe the associated morbidity and mortality pattern in them. A prospective cross sectional study was conducted and we studied one hundred consecutive jaundiced neonates (55 males, 45 females) presenting at Aminu Kano Teaching Hospital from between 2004 and August 2005. G-6-PD activity was assayed by Quantitative spectrophotometric method of Kornberg; serum bilirubin and haemoglobin levels were estimated by standard techniques. Exposure to possible Icterogenic agents, clinical features of kernicterus and the outcome were noted.Results: The incidence of G-6-PD deficiency was found to be 46% with male to female ratio of 3:1 (Χ2 = 15, p = 0.001). A higher proportion (60.6%) of the inborn neonates had G-6-PD deficiency (X2 = 5.5, p = 0.06). Jaundice was noticed significantly earlier in the G-6-PD deficient neonates (mean = 2.0, SD = 1 days) compared to (mean = 2.7, SD = 1.6 days) in the sufficient neonates (t = 2.3, p = 0.02). Sixteen (16%) neonates developed kernicterus, of these 10 (63%) were G-6-PD deficient. The mortality rate among G-6-PD deficient neonates was 15% (7 of 46) twice as much as in the sufficient neonates 7% (4 of 54). Only six neonates 0.6% ware exposed to naphthalene of whom three were G -6PD deficient. Five babies were given traditional medicine two of which were G6-PD deficient.Conclusion: G-6-PD deficiency is an important risk factor for neonatal jaundice. Jaundice appeared early in the deficient neonates. There is high incidence of kernicterus and mortality among them. Low admission weight significantly contributed to the mortality.Key Words: G-6-PD deficiency; Neonatal Jaundice; Kernicteru

3-D GRMHD and GRPIC Simulations of Disk-Jet Coupling and Emission

We investigate jet formation in black-hole systems using 3-D General Relativistic Particle-In-Cell (GRPIC) and 3-D GRMHD simulations. GRPIC simulations, which allow charge separations in a collisionless plasma, do not need to invoke the frozen condition as in GRMHD simulations. 3-D GRPIC simulations show that jets are launched from Kerr black holes as in 3-D GRMHD simulations, but jet formation in the two cases may not be identical. Comparative study of black hole systems with GRPIC and GRMHD simulations with the inclusion of radiate transfer will further clarify the mechanisms that drive the evolution of disk-jet systems.Comment: 3 pages, 1 figure, Proceedings of the Eleventh Marcel Grossmann Meeting on General Relativity, edited by H. Kleinert, R.T. Jantzen and R. Ruffini, World Scientific, Singapore, 200

Dynamics of one-dimensional tight-binding models with arbitrary time-dependent external homogeneous fields

The exact propagators of two one-dimensional systems with time-dependent external fields are presented by following the path-integral method. It is shown that the Bloch acceleration theorem can be generalized to the impulse-momentum theorem in quantum version. We demonstrate that an evolved Gaussian wave packet always keeps its shape in an arbitrary time-dependent homogeneous driven field. Moreover, that stopping and accelerating of a wave packet can be achieved by the pulsed field in a diabatic way.Comment: 8 pages, 6 figure

Directly phase-modulated light source

The art of imparting information onto a light wave by optical signal modulation is fundamental to all forms of optical communication. Among many schemes, direct modulation of laser diodes stands out as a simple, robust, and cost-effective method. However, the simultaneous changes in intensity, frequency, and phase have prevented its application in the field of secure quantum communication. Here, we propose and experimentally demonstrate a directly phase-modulated light source which overcomes the main disadvantages associated with direct modulation and is suitable for diverse applications such as coherent communications and quantum cryptography. The source separates the tasks of phase preparation and pulse generation between a pair of semiconductor lasers leading to very pure phase states. Moreover, the cavity-enhanced electro-optic effect enables the first example of subvolt half-wave phase modulation at high signal rates. The source is compact, stable, and versatile, and we show its potential to become the standard transmitter for future quantum communication networks based on attenuated laser pulses

The role of high-level calculations in the assignment of the Q-band spectra of chlorophyll

© 2014 AIP Publishing LLC. We recently established a novel assignment of the visible absorption spectrum of chlorophyll-a that sees the two components Qx and Qy of the low-energy Q band as being intrinsically mixed by non-adiabatic coupling. This ended 50 years debate as to the nature of the Q bands, with prior discussion poised only in the language of the Born-Oppenheimer and Condon approximations. The new assignment presents significant ramifications for exciton transport and quantum coherence effects in photosystems. Results from state of the art electronic structure calculations have always been used to justify assignments, but quantitative inaccuracies and systematic failures have historically limited usefulness. We examine the role of CAM-B3LYP time-dependent density-functional theory (TD-DFT) and Symmetry Adapted Cluster-Configuration Interaction (SAC-CI) calculations in first showing that all previous assignments were untenable, in justifying the new assignment, in making some extraordinary predictions that were vindicated by the new assignment, and in then identifying small but significant anomalies in the extensive experimental data record

Best-Practice Criteria for Practical Security of Self-Differencing Avalanche Photodiode Detectors in Quantum Key Distribution

Fast gated avalanche photodiodes (APDs) are the most commonly used single photon detectors for high bit rate quantum key distribution (QKD). Their robustness against external attacks is crucial to the overall security of a QKD system or even an entire QKD network. Here, we investigate the behavior of a gigahertz-gated, self-differencing InGaAs APD under strong illumination, a tactic Eve often uses to bring detectors under her control. Our experiment and modelling reveal that the negative feedback by the photocurrent safeguards the detector from being blinded through reducing its avalanche probability and/or strengthening the capacitive response. Based on this finding, we propose a set of best-practice criteria for designing and operating fast-gated APD detectors to ensure their practical security in QKD

Pentalogy of Cantrell - A Case Report from Nigeria

FB was delivered at home to a para three low income mother, at term after an unsupervised pregnancy. At birth she was noticed to have an anterior chest wall defect with a protruding pulsating mass. Further examination revealed a defect from the suprasternal notch to the xiphoid process (bifid sternum) with the heart exposed and pulsating (ectopia cordis). The pericardium was absent and the great vessels were exposed. There was an epigastric omphalocoele and a ventral diaphragmatic defect. The diagnosis of Pentallogy of Cantrell was made. The challenges involved in the evaluation and management of this case in a Nigerian setting are discussed. Keywords: Pentallogy, Cantrell, Nigeri

Gigahertz-gated InGaAs/InP single-photon detector with detection efficiency exceeding 55% at 1550 nm

We report on a gated single-photon detector based on InGaAs/InP avalanche photodiodes (APDs) with a single-photon detection efficiency exceeding 55% at 1550 nm. Our detector is gated at 1 GHz and employs the self-differencing technique for gate transient suppression. It can operate nearly dead time free, except for the one clock cycle dead time intrinsic to self-differencing, and we demonstrate a count rate of 500 Mcps. We present a careful analysis of the optimal driving conditions of the APD measured with a dead time free detector characterization setup. It is found that a shortened gate width of 360 ps together with an increased driving signal amplitude and operation at higher temperatures leads to improved performance of the detector. We achieve an afterpulse probability of 7% at 50% detection efficiency with dead time free measurement and a record efficiency for InGaAs/InP APDs of 55% at an afterpulse probability of only 10.2% with a moderate dead time of 10 ns.L. C. Comandar acknowledges personal support via the EPSRC funded CDT in Photonics System Development.This is the author accepted manuscript. The final version is available via AIP at http://scitation.aip.org/content/aip/journal/jap/117/8/10.1063/1.4913527