A kinetics study of the homogeneous and heterogeneous components of the HCl + ClONO_2 reaction

The kinetics of the reaction HCl + ClONO_2 → Cl_2 + HNO_3 were investigated at 298 K using a flow reactor with FTIR analysis to assess the importance of this reaction for stratospheric chemistry. The observed reaction was characteristic of a heterogeneous process; an upper limit of 5 × 10^(−18) cm³ molecule^(−1) s^(−1) was obtained for the homogeneous gas phase rate constant. From calculations of the first order wall rate constant, estimates were made of the reaction rate on stratospheric aerosols. Because both HCl and ClONO_2 need to be adsorbed on the particle surface, the reaction will be of negligible importance under most stratospheric conditions

Topological and functional aspects of the proton conductor, F0_0, of the Escherichia coli ATP-synthase

The isolated H$^+$ conductor, F$_0$ , of the Escherichia co1i ATP-synthase consists of three subunits, a, b, and c. H$^+$ -permeable liposomes can be reconstit~ted with F$_0$ and lipids; addition of F$_1$-ATPase reconstitutes a functional ATP-synthase. Mutants with altered or misslng F$_0$ subunits are defective in H$^+$ conduction. Thus, all three subunits are necessary for the expression of H$^+$ conduction. The subunits a and b contain binding sites for F$_1$• Computer calculations, cross-links, membrane-permeating photo-reactive labels, and proteases were used to develop tentative structural models for the individual F$_0$ subunits

Towards a 3-D tomographic retrieval for the air-borne limb-imager GLORIA

GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) is a new remote sensing instrument essentially combining a Fourier transform infrared spectrometer with a two-dimensional (2-D) detector array in combination with a highly flexible gimbal mount. It will be housed in the belly pod of the German research aircraft HALO (High Altitude and Long Range Research Aircraft). It is unique in its combination of high spatial and state-of-the art spectral resolution. Furthermore, the horizontal view angle with respect to the aircraft flight direction can be varied from 45° to 135°. This allows for tomographic measurements of mesoscale events for a wide variety of atmospheric constituents. <br><br> In this paper, a tomographic retrieval scheme is presented, which is able to fully exploit the manifold radiance observations of the GLORIA limb sounder. The algorithm is optimized for massive 3-D retrievals of several hundred thousands of measurements and atmospheric constituents on common hardware. The new scheme is used to explore the capabilities of GLORIA to sound the atmosphere in full 3-D with respect to the choice of the flightpath and to different measurement modes of the instrument using ozone as a test species. It is demonstrated that the achievable resolution should approach 200 m vertically and 20 km–30 km horizontally. Finally, a comparison of the 3-D inversion with conventional 1-D inversions using the assumption of a horizontally homogeneous atmosphere is performed

Neutron Scattering and the B_{1g} Phonon in the Cuprates

The momentum dependent lineshape of the out-of-phase oxygen vibration as measured in recent neutron scattering measurements is investigated. Starting from a microscopic coupling of the phonon vibration to a local crystal field, the phonon lineshift and broadening is calculated as a function of transfered momentum in the superconducting state of YBa$_{2}$Cu$_{3}$O$_{7}$. It is shown that the anisotropy of the density of states, superconducting energy gap, and the electron-phonon coupling are all crucial in order to explain these experiments.Comment: new figures and discussio

Optimal phase estimation in quantum networks

We address the problem of estimating the phase phi given N copies of the phase rotation u(phi) within an array of quantum operations in finite dimensions. We first consider the special case where the array consists of an arbitrary input state followed by any arrangement of the N phase rotations, and ending with a POVM. We optimise the POVM for a given input state and fixed arrangement. Then we also optimise the input state for some specific cost functions. In all cases, the optimal POVM is equivalent to a quantum Fourier transform in an appropriate basis. Examples and applications are given.Comment: 9 pages, 2 figures; this is an extended version of arXiv:quant-ph/0609160. v2: minor corrections in reference

Automated Classification of Airborne Laser Scanning Point Clouds

Making sense of the physical world has always been at the core of mapping. Up until recently, this has always dependent on using the human eye. Using airborne lasers, it has become possible to quickly "see" more of the world in many more dimensions. The resulting enormous point clouds serve as data sources for applications far beyond the original mapping purposes ranging from flooding protection and forestry to threat mitigation. In order to process these large quantities of data, novel methods are required. In this contribution, we develop models to automatically classify ground cover and soil types. Using the logic of machine learning, we critically review the advantages of supervised and unsupervised methods. Focusing on decision trees, we improve accuracy by including beam vector components and using a genetic algorithm. We find that our approach delivers consistently high quality classifications, surpassing classical methods

Анализ пожарной опасности предприятий по переработке и выпуску упаковочных материалов из пластика

В статье освящаются вопросы, касающиеся предприятий по переработке и выпуску упаковочных материалов из пластика, а так же анализ их пожарной опасности.The article highlights the issues related to enterprises for the processing and production of plastic packaging materials, as well as an analysis of their fire hazards

A kinetics study of the homogeneous and heterogeneous components of the HCl + ClONO_2 reaction

The kinetics of the reaction HCl + ClONO_2 → Cl_2 + HNO_3 were investigated at 298 K using a flow reactor with FTIR analysis to assess the importance of this reaction for stratospheric chemistry. The observed reaction was characteristic of a heterogeneous process; an upper limit of 5 × 10^(−18) cm³ molecule^(−1) s^(−1) was obtained for the homogeneous gas phase rate constant. From calculations of the first order wall rate constant, estimates were made of the reaction rate on stratospheric aerosols. Because both HCl and ClONO_2 need to be adsorbed on the particle surface, the reaction will be of negligible importance under most stratospheric conditions

3-D tomographic observations of Rossby wave breaking over the North Atlantic during the WISE aircraft campaign in 2017

This paper presents measurements of ozone, water vapour and nitric acid (HNO3) in the upper troposphere/lower stratosphere (UTLS) over North Atlantic and Europe. The measurements were acquired with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) during the Wave Driven Isentropic Exchange (WISE) campaign in October 2017. GLORIA is an airborne limb imager capable of acquiring both 2-D data sets (curtains along the flight path) and, when the carrier aircraft is flying around the observed air mass, spatially highly resolved 3-D tomographic data. Here, we present a case study of a Rossby wave (RW) breaking event observed during two subsequent flights 2 d apart. RW breaking is known to steepen tracer gradients and facilitate stratosphere–troposphere exchange (STE). Our measurements reveal complex spatial structures in stratospheric tracers (ozone and nitric acid) with multiple vertically stacked filaments. Backward-trajectory analysis is used to demonstrate that these features are related to several previous Rossby wave breaking events and that the small-scale structure of the UTLS in the Rossby wave breaking region, which is otherwise very hard to observe, can be understood as stirring and mixing of air masses of tropospheric and stratospheric origin. It is also shown that a strong nitric acid enhancement observed just above the tropopause is likely a result of NOx production by lightning activity. The measurements showed signatures of enhanced mixing between stratospheric and tropospheric air near the polar jet with some transport of water vapour into the stratosphere. Some of the air masses seen in 3-D data were encountered again 2 d later, stretched to very thin filament (horizontal thickness down to 30 km at some altitudes) rich in stratospheric tracers. This repeated measurement allowed us to directly observe and analyse the progress of mixing processes in a thin filament over 2 d. Our results provide direct insight into small-scale dynamics of the UTLS in the Rossby wave breaking region, which is of great importance to understanding STE and poleward transport in the UTLS