Characterization of the OCO-2 instrument line shape functions using on-orbit solar measurements

Accurately characterizing the instrument line shape (ILS) of the Orbiting Carbon Observatory-2 (OCO-2) is challenging and highly important due to its high spectral resolution and requirement for retrieval accuracy (0. 25 %) compared to previous spaceborne grating spectrometers. On-orbit ILS functions for all three bands of the OCO-2 instrument have been derived using its frequent solar measurements and high-resolution solar reference spectra. The solar reference spectrum generated from the 2016 version of the Total Carbon Column Observing Network (TCCON) solar line list shows significant improvements in the fitting residual compared to the solar reference spectrum currently used in the version 7 Level 2 algorithm in the O₂ A band. The analytical functions used to represent the ILS of previous grating spectrometers are found to be inadequate for the OCO-2 ILS. Particularly, the hybrid Gaussian and super-Gaussian functions may introduce spurious variations, up to 5 % of the ILS width, depending on the spectral sampling position, when there is a spectral undersampling. Fitting a homogeneous stretch of the preflight ILS together with the relative widening of the wings of the ILS is insensitive to the sampling grid position and accurately captures the variation of ILS in the O₂ A band between decontamination events. These temporal changes of ILS may explain the spurious signals observed in the solar-induced fluorescence retrieval in barren areas

Experiments to shed light on the best way to use Iterated Local Search for a complex combinatorial problem

Iterated Local Search (ILS) is a popular metaheuristic search technique for use on combinatorial optimisation problems. As with most such techniques, there are many ways in which ILS can be implemented. The aim of this paper is to shed light on the best variants and choice of parameters when using ILS on a complex combinatorial problem with many objectives, by reporting on the results of an exhaustive set of experimental computer runs using ILS for a real-life sports scheduling problem. The results confirm the prevailing orthodoxy that a random element is ended for the ILS "kick", but also concludes that a non-random element can be valuable if it is chosen intelligently. Under these circumstances it is also found that the best ILS acceptance criterion to choose appears to depend upon the length of the run; for short runs, a high-diversification approach works best; for very long runs a high-intensification approach is best; while between these extremes, a more sophisticated approach using simulated annealing or threshold methods appears to be best

Game on! a report on the interactive leisure software subsector in London

There is a paucity of good quality data on the UK video games industry. Information such as value-added, investment on R&D, average annual expenditure on training and the value of video games in terms of exports, for example, is thin or incomplete. This is a serious problem. If we are to improve the competitiveness of the UK games development sector then we must have better quality information. Games developers will then be able to benchmark their business activities against industry averages. Overseas investors will also then be better informed about the benefits of investing in the UK leisure software sector. This Report confirms the lacunae in our knowledge that exists about the video games industry. For example, the Office of National Statistics still does not have a specific code to identify interactive leisure software businesses. Yet the Report also shines a light on the video games industry in the UK in general and in London in particular

Ionic Liquids containing metallic nucleus

In this PhD thesis, new methods to solubilize metal salts in ionic liquids (ILs) were developed and the behavior of the new metal containing ILs was studied. To incorporate metals in ILs, till now, anions (chloride, bromide, dicyanamide) able to give strong complexes with metals or the introduction of specific functional groups on cation or anion able to interact with the metal cation have been used. In all these cases, chemical nature of metal is changed by the interaction with other atoms and formation of new chemical bonds. To have weakly coordinated or relatively “free” cations in ILs, new kind of salts, with very soft anions have been used. New metallic salts, with Tf2N- as anion, were dissolved in suitable ionic liquids obtaining high concentrated solutions. Experiments performed using different classes of ILs evidenced that ILs having the same anion of the added metal salt generally assure a relevant solubility. A new common anion effect was invoked. The physical-chemical properties of the metal containing solutions were determined as function of concentration and temperature. Moreover, new ILs bearing cations or anions able to interact with the metal center were synthesized. In this contest basic 1,4-diazabicyclo[2.2.2]octane (dabco) based ILs bearing different alkyl chains and having as counter anion dicyanamide were synthesized and characterized as well as imidazolium based ILs functionalized with hydroxyl substituted alkyl chains (glycerol) or polymerizable groups (allyl, vinyl and styril groups). The interaction between dicyanamide anion and metals, especially in copper-catalyzed reactions was investigated. Since the purity degree of ILs is very important for their application in synthesis, especially when ILs must be used in metal catalyzed reactions, or when kinetics studies have to be performed, a new cheap and easily accessible method to purify ILs from organic solvents and unreacted reagents was developed and applied. Highly “pure” ILs, so generated, were used in the kinetic study of oxidation reactions performed using with singlet oxygen

An analytical comparison of coalescent-based multilocus methods: The three-taxon case

Incomplete lineage sorting (ILS) is a common source of gene tree incongruence in multilocus analyses. A large number of methods have been developed to infer species trees in the presence of ILS. Here we provide a mathematical analysis of several coalescent-based methods. Our analysis is performed on a three-taxon species tree and assumes that the gene trees are correctly reconstructed along with their branch lengths

The Scaled-Charge Additive Force Field for Amino Acid Based Ionic Liquids

Abstract. Ionic liquids (ILs) constitute an emerging field of research. New ILs are continuously introduced involving more and more organic and inorganic ions. Amino acid based ILs (AAILs) represent a specific interest due to their evolutional connection to proteins. We report a new non- polarizable force field (FF) for the eight AAILs comprising 1-ethyl-3-methylimidazolium cation and amino acid anions. The anions were obtained via deprotonation of carboxyl group. Specific cation-anion non-covalent interactions have been taken into account by computing electrostatic potential for ion pairs, in contrast to isolated ions. The van der Waals interactions have been transferred from the CHARMM36 FF with minor modifications. Therefore, compatibility between our parameters and CHARMM36 parameters is preserved. Our FF can be easily implemented using a variety of popular molecular dynamics programs. It will find broad applications in computational investigation of ILs

Human-centric light sensing and estimation from RGBD images: the invisible light switch

Lighting design in indoor environments is of primary importance for at least two reasons: 1) people should perceive an adequate light; 2) an effective lighting design means consistent energy saving. We present the Invisible Light Switch (ILS) to address both aspects. ILS dynamically adjusts the room illumination level to save energy while maintaining constant the light level perception of the users. So the energy saving is invisible to them. Our proposed ILS leverages a radiosity model to estimate the light level which is perceived by a person within an indoor environment, taking into account the person position and her/his viewing frustum (head pose). ILS may therefore dim those luminaires, which are not seen by the user, resulting in an effective energy saving, especially in large open offices (where light may otherwise be ON everywhere for a single person). To quantify the system performance, we have collected a new dataset where people wear luxmeter devices while working in office rooms. The luxmeters measure the amount of light (in Lux) reaching the people gaze, which we consider a proxy to their illumination level perception. Our initial results are promising: in a room with 8 LED luminaires, the energy consumption in a day may be reduced from 18585 to 6206 watts with ILS (currently needing 1560 watts for operations). While doing so, the drop in perceived lighting decreases by just 200 lux, a value considered negligible when the original illumination level is above 1200 lux, as is normally the case in offices

Operando STM study of the interaction of imidazolium-based ionic liquid with graphite

Understanding interactions at the interfaces of carbon with ionic liquids (ILs) is crucially beneficial for the diagnostics and performance improvement of electrochemical devices containing carbon as active materials or conductive additives in electrodes and ILs as solvents or additives in electrolytes. The interfacial interactions of three typical imidazolium-based ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (AMImTFSI) ILs having ethyl (C2), butyl (C4) and octyl (C8) chains in their cations, with highly oriented pyrolytic graphite (HOPG) were studied in-situ by electrochemical scanning tunneling microscopy (EC-STM). The etching of HOPG surface and the exfoliation of graphite/graphene flakes as well as cation intercalation were observed at the HOPG/C2MImTFSI interface. The etching also takes place in C4MImTFSI at −1.5 V vs Pt but only at step edges with a much slower rate, whereas C8MIm+ cations adsorbs strongly on the HOPG surface under similar conditions with no observable etching or intercalation. The EC-STM observations can be explained by the increase in van der Waals interaction between the cations and the graphite surface with increasing length of alkyl chains