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We develop a 1-D atmospheric photochemistry model for Mars to interpret hydrogen chloride (HCl) profile measurements collected by the ACS MIR spectrometer aboard the ExoMars Trace Gas Orbiter (TGO) in Mars Year (MY) 34. We include a gas-phase chlorine chemistry scheme and study 1) surface chemistry, 2) hydrolysis, 3) photolysis, and 4) hydration and photolysis of dust grains as possible sources of gas-phase chlorine chemistry. Heterogeneous uptake of chlorine species onto water ice and minerals in Martian dust are loss processes common to all mechanisms. We drive the 1-D model using TGO profile measurements of aerosols and water vapour. We find that mechanism four can reproduce observed HCl profile tendencies during MY34. It reproduces the HCl cut-off at high southern latitudes (

Carbon monoxide is a non-condensable gas in the Martian atmosphere produced by the photolysis of CO2. Its abundance responds to the condensation and sublimation of CO2 from the polar caps, resulting in seasonal variations of the CO mixing ratio. ACS onboard the ExoMars Trace Gas Orbiter have measured CO in infrared bands by solar occultation. Here we provide the first long-term monitoring of the CO vertical distribution at the altitude range from 0 to 80 km for 1.5 Martian years from Ls = 163° of MY34 to the end of MY35. We obtained a mean CO mixing ratio of ∼960 ppmv at latitudes from 45°S to 45°N and altitudes below 40 km, mostly consistent with previous observations. We found a strong enrichment of CO near the surface at Ls = 100–200° in high southern latitudes with a layer of 3,000–4,000 ppmv, corresponding to local depletion of CO2. At equinoxes we found an increase of the CO mixing ratio above 50 km to 3,000–4,000 ppmv at high latitudes of both hemispheres explained by the downwelling flux of the Hadley circulation on Mars, which drags the CO enriched air. General circulation models tend to overestimate the intensity of this process, bringing too much CO. The observed minimum of CO in the high and mid-latitudes southern summer atmosphere amounts to 700–750 ppmv, agreeing with nadir measurements. During the global dust storm of MY34, when the H2O abundance peaks, we see less CO than during the calm MY35, suggesting an impact of HOx chemistry on the CO abundance.

1. Introduction Thermal infrared datasets from planetary bodies have the potential to provide key insights for the understanding of a planet's climate evolution and history: valuable information about composition, temperature and state of the atmosphere can be retrieved from thermal spectral data.In this work, we present the application of a methodology based on Principal Component Analysis (PCA) and Target Transformation (TT) Factor Analysis (FA) techniques to thermal infrared data of the ExoMars2016 Trace Gas Orbiter (TGO) with the main goal to retrieve the different particulate atmospheric contributions present in the spectra and separate them from the surface contributions. 2. Instrument and dataset TGO has a suite of spectroscopic instruments for the investigation of the Red Planet in the infrared spectral range known as Atmospheric Chemistry Suite (ACS) [1] consisting of three spectrometers observing Mars in solar occultation, nadir and limb geometry in the Near-InfraRed (NIR), Mid-InfraRed (MIR) and Thermal InfraRed (TIR) spectral channels. Among them, the ACS thermal-infrared channel (TIRVIM) covers the spectral range between 1.7-17 μm with apodized resolution varying from 0.2 to 1.3 cm−1 [1]. TIRVIM has similar capabilities to IRIS (Mariner 9), TES, and PFS in several aspects, but has some advantages: - higher spectral resolution; - better noise equivalent radiance (from 0.08 mW/m2/sr-1/cm-1); - dense spatial coverage (TGO has a circular orbit of 400 km) [1].Martian TIRVIM spectra acquired along the orbits that cross Elysium Planitia, landing site of the NASA’s Insight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) lander, were here analyzed. The selected data orbits span from Ls=150°C to Ls=210°C, covering part of the Martian summer and of the Martian autumn going through the autumn equinox in the northern hemisphere of the planet. Corresponding Local Times cover Martian days and nights. 3. Methodology To analyze the ExoMars TIRVIM data and retrieve and characterize the number of varying atmospheric components present in these data and their spectral shape, a methodology was applied based on a combination of PCA and TT – FA techniques [2, 3]. These techniques are demonstrated to be able to extract the composition of laboratory samples [4, 5]; to extract the principal varying components from a big spectral dataset in the thermal infrared [3], and then to identify them as components of the atmosphere and separate their contribution from surface emission [6]. This methodology, previously successfully adopted for the analysis of TES and PFS data [2, 7], was, here, applied for the first time to the analysis of the new and at higher spectral resolution TIRVIM dataset. Considering that the PCA works best when the different components have significant variation in the data, we selected data where these variations are more likely to occur: the analyzed data cover diurnal as well as seasonal variations. A list of PFS and TES atmospheric end-members extracted from [3] and [2] were used as initial guess for the TT, to interpret the abstract eigenvectors retrieved from the PCA and attribute them a physically coherent meaning. 4. Results and future developments Spectral shapes of atmospheric dust and water ice aerosols were recovered from the analyzed TIRVIM data. Comparisons with results previously obtained on PFS and TES data (Figure 1) validate the methodology used and show that it is capable of determining the number of independently variable components and recovering the spectral endmembers present in the TIRVIM data. Figure 1. Comparison between the general TES/PFS extracted endmembers [2, 3] (upper panel) and the endmembers extracted from the TIRVIM data in this work (bottom panel). Grey area: wavelength cut due to high instrumental noise. Deconvolution of the original spectra using the recovered spectral end-members allowed us to obtain the concentration coefficients of the dust and water ice end-members and retrieved abundances maps. The results obtained are promising in terms of identification and separation of the atmospheric components and have strong impact on the identification of surface contributions in the spectra. We are further investigating this point with the main goal of showing the potential of this method to extract valuable information from TIRVIM data not only on the atmosphere, but also on the surface of the Red Planet. Derived surface emissivity products are being analyzed by linear deconvolution analysis with the laboratory spectral database of Martian analogues measured at the Planetary Spectroscopy Laboratory (PSL) of DLR, in Berlin [5]. Acknowledgments ExoMars is a space mission of ESA and Roscosmos. The ACS experiment is led by IKI, the Space Research Institute in Moscow, assisted by LATMOS in France. The science operations of ACS are funded by Roscosmos and ESA. References [1] Korablev et al. (2018) Space Science Review, 214:7. [2] D’Amore M. et al. (2013) Icarus, 226, 1294-1303. [3] Bandfield J.L., Christensen P.R., Smith M.D. (2000) JGR, 105 (E4), 9573-9587. [4] Smith, M.O., Adams, J.B., Johnson, P.E. (1985) JGR, 90, 797-804. [5] Alemanno G., Maturilli A., D’Amore M., Helbert J. (2021) Icarus, 368. [6] Smith M. D., Bandfield J. L. and Christensen P.R. (2000) JGR, 85 (E4), 9589-9607. [7] Maturilli, A., Helbert, J., D’Amore, M. (2009) EPSC2009, Abstract #EPSC2009-106.

Introduction: Between March 2018 and December 2019, millions of spectra of Mars' surface and atmosphere thermal emission have been recorded in nadir geometry by TIRVIM/ACS, a thermal infrared spectrometer onboard the ExoMars Trace Gas Orbiter (TGO) [7]. From this wealth of data, we characterized in detail the thermal structure of the Martian lower atmosphere at a great variety of local times. Here we focus on the study of migrating thermal tides derived from TIRVIM observations, including during the Global Dust Event of MY34. Observations and Methods: We have developed an algorithm coupling line-by-line radiative transfer and optimal estimation theory to retrieve the surface temperature, the vertical profiles of the temperature between a few km and 50-55 km (2–3 Pa), and the integrated optical depth of dust and water ice clouds [3]. The retrieved temperature profiles have a vertical resolution of 10 km in the lower atmosphere and a coarser resolution of 15-20 km in the range 2–20 Pa. They were validated against thousands of co-located observations from the Mars Climate Sounder, acquired in limb viewing geometry [3]. Thermal structure and tides: Thermal tides are planetary-scale oscillations resulting from the diurnal solar forcing of the thin Martian atmosphere. Migrating tides describe sun-synchronous modes propagating westward with the sun. The diurnal mode has one maximum and one minimum per day and a zonal wavenumber of one; the semi-diurnal mode has two maxima and two minima per day and a zonal wavenumber of two; etc. One of the main advantage of TGO’s orbit is that the local time of TIRVIM nadir observations drifts by 13 minutes earlier each sol. After 54 sols, or 25-35° of Ls, a full coverage of the daily cycle is achieved, allowing to separate between diurnal and seasonal temperature variations. This is clearly an asset to study thermal tides compared to previous studies, mostly based on 2-4 AM and 2-4 PM temperatures obtained from sun-synchronous orbiters [1,4,6,9]. An example of the zonally-averaged temperature retrieved from TIRVIM at 30 Pa in the period March 13 - April 28, 2018 (Ls~150° of MY34) is shown below, as a function of latitude and local time. At the equator, the temperature is found maximum near 3~AM and minimum near 7~PM. This feature of warm nighttime temperatures at this altitude is well known and is a manifestation of the diurnal thermal tide [8]. The fact that these two temperature extrema are not separated by 12 hours is a first hint that the thermal field is also influenced by a semi-diurnal tide. Figure 1: Zonally-averaged temperature retrieved from TIRVIM/ACS at 30 Pa, with latitude and local time. This figure gathers 45 sols of data around Ls~150°, MY34. To study migrating tides qualitatively, we consider the zonally-averaged temperature in a fixed local time reference frame, in which other types of wave signatures (stationary waves, non-migrating tides,…) are averaged out. Following [6], we decompose the observed zonally-averaged temperature into a daily-averaged temperature plus sinusoidal functions at diurnal, semi-diurnal and ter-diurnal frequencies. We obtain the amplitude and phase of the migrating tides at each pressure level and 10°-wide latitudinal bin (see below an example of fits). An amplitude of 4K is found for the diurnal mode near the equator, which decreases to 2K near 20°, and increases to 6K near 50°N. Very similar results are found at Ls~90° for MY35 [2]. We employ the same methodology to derive tides characteristics simulated in the LMD GCM. Temperature profiles from the model are extracted at the same locations and times as TIRVIM observations and are smoothed vertically using the appropriate averaging kernel matrix. The modeled tides exhibit very similar characteristics as those observed, except for a 1 to 2 hours phase shift; temperature extrema occurring at later local times in the model. Figure 2: Fit (purple) to TIRVIM equatorial temperatures at 50 Pa (black stars, upper part) as a function of local time. It combines a daily average temperature (horizontal dashed line), diurnal and semi-diurnal signals, as labeled. The bottom part shows the same for GCM outputs (shifted by -15K). One caveat is that even small seasonal variations over a martian month can hamper our analysis when characterizing the semi-diurnal tide [2]. To overcome this issue, we de-trend the data for seasonal variations using MCS observations. The derived amplitude of the semi-diurnal tide near the equator at Ls=150° ranges from 2K (at 100 Pa) to 6K (at 2 Pa), confirming that this tide mode is significant even in non-dusty seasons [6]. Impact of the MY34 GDE: A Global Dust Event started locally on 2 June 2018 and became planet-encircling on 21 June [5]. Compared to pre-storm conditions, we find that the diurnal tide amplitude strongly increases, reaching 32K at 50-60°S and 20K at 50-60°N at 50 Pa, while it remains unchanged (~4K) near the equator. The semi-diurnal mode increases slightly (6-8K at 30-50 Pa, equator), while the ter-diurnal mode is also detected (amplitude of 5K near 50 Pa, equator). GCM simulations run with the MY34 dust scenario agree very well with TIRVIM observations, both in terms of thermal structure and tide characteristics. Bibliography: [1] Banfield et al., JGR Vol. 105, 2000. [2] Fan et al., GRL Vol. 49, 2022. [3] Guerlet et al., JGR Vol. 127, 2022. [4] Guzewich et al., JGR Vol. 117, 2012. [5] Kass et al., GRL Vol. 47, 2020. [6] Kleinbohl et al., GRL Vol. 40, 2013. [7] Korablev et al., SSR Vol. 214, 2018. [8] Lee et al., JGR Vol. 114, 2009. [9] Wilson et al., GRL Vol. 27, 2000.

A wide-field zenith-looking telescope operating in a mode similar to Time-Delay-Integration (TDI) or drift scan imaging can perform an infrared sky survey without active pointing control but it requires a high-speed, low-noise infrared detector. Operating from a hosted payload platform on the International Space Station (ISS), the Emu space telescope employs the paradigm-changing properties of the Leonardo SAPHIRA electron avalanche photodiode array to provide powerful new observations of cool stars at the critical water absorption wavelength (1.4 $\mu$m) largely inaccessible to ground-based telescopes due to the Earth's own atmosphere. Cool stars, especially those of spectral-type M, are important probes across contemporary astrophysics, from the formation history of the Galaxy to the formation of rocky exoplanets. Main sequence M-dwarf stars are the most abundant stars in the Galaxy and evolved M-giant stars are some of the most distant stars that can be individually observed. The Emu sky survey will deliver critical stellar properties of these cool stars by inferring oxygen abundances via measurement of the water absorption band strength at 1.4 $\mu$m. Here we present the TDI-like imaging capability of Emu mission, its science objectives, instrument details and simulation results., Comment: Accepted for publication in Journal of Astronomical Telescopes, Instruments, and Systems (JATIS)

Thermal tides in the Martian atmosphere are analyzed using temperature profiles retrieved from nadir observations obtained by the TIRVIM Fourier-spectrometer, part of the Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO). The data is selected near the northern summer solstice at solar longitude (LS) 75{\deg}-105{\deg} of Martian Year (MY) 35. The observations have a full local time coverage, which enables analyses of daily temperature anomalies. The observed zonal mean temperature is lower by 4-6K at ~100Pa, but higher towards the summer pole, compared to the LMD Mars General Circulation Model (GCM). Wave mode decomposition shows dominant diurnal tide and important semi-diurnal tide and diurnal Kelvin wave, with maximal amplitudes of 5K, 3K, and 2.5K, respectively, from tens to hundreds of Pa. The results generally agree well with the LMD Mars GCM, but with noticeable earlier phases of diurnal (~1h) and semi-diurnal (~3h) tides., Comment: 7 pages, 4 figures, accepted by GRL

Polysemy, when a single term has multiple meanings, and synonymy, when multiple terms have the same meaning, are common phenomena in linguistics as well as in scientific knowledge. In ontology engineering, it is vital to detect the synonyms annotations and the multiple inheritances because of polysemy. The persistence of these issues in the semantic description of a knowledge domain causes problematic interoperability and data processing. The disambiguation of the entities, properties and relationships sense in a semantic web ontology significantly improves linked data generation and information retrieval. We explore the synonymy and polysemy in the setting of a cardiology terminology generated from textbooks on the basis of field coverage, professionals’ associations’ recommendations and bibliometrics, for the building of a cardiologic ontology. From 56,134 terms collected we found that 67.7% were unique. The indexed terms included single words, compound words and multi-word expressions. The frequency of their appearances in the combined master index was calculated and used as a marker of their significance. To cope with the linguistic polysemy and synonymy of terms, we examined them in WordNet, MeSH and BioPortal, as well as by latent semantic analysis (LSA) through singular value decomposition (SVD). Through these approaches we managed to identify and decipher semantic associations and relationships between the terms. We proposed a roadmap for ontology building from scratch by utilizing intrinsic and extrinsic knowledge resources and reuse of metadata. We anticipate that this approach is applicable in ontology engineering of different knowledge domains for relationships setting and linked data contextualization

Evaluation of circulating group B streptococcus (GBS) strains is important to assess the potential effects of GBS prevention strategies in a certain region. This study aimed at estimating the distributions of capsular polysaccharide (CPS) types and pilus profiles, and the rates of antimicrobial resistance among GBS strains isolated from colonized pregnant women and newborns in 2010-2011 and 2017-2018 in St. Petersburg, Russia. A total of 261 GBS isolates have been investigated. Antibiotic susceptibility testing was performed using the disc-diffusion method. CPS types and pilus profiles were determined by using PCR. Over the 9-year period, the resistance of GBS to both erythromycin and clindamycin has significantly increased, exceeding 30% in 2017-2018. The most prevalent CPS types were Ia, III, and V. Significant shifts were observed in the frequency of CPS types III (decreased) and V (increased), which resulted in a significant reduction (from 77 to 63%) in the potential coverage by a trivalent vaccine (including serotypes Ia, Ib, and III), whereas that of a pentavalent vaccine (including serotypes Ia, Ib, II, III, and V) remained largely unchanged (approximately 95%). The most common pilus profiles were PI-1/2a, PI-2a, and PI-1a/2b, and pilus genotype distribution has not changed with time. High and steadily growing resistance of perinatal GBS strains to clindamycin requires restricting its use to penicillin-allergic women at high risk for anaphylaxis and testing the GBS strains for their susceptibility to this antibiotic. A pentavalent CPS-based vaccine covers the vast majority of perinatal GBS strains in Russia.

This paper studies the properties of the Russian stock market by employing the data-driven science and network approaches. The theory of complex networks allows us to build and examine topological network structures of the market with the further identification of relationships between stocks and the analysis of hidden information and market dynamics. In this paper we will present an analysis of structural and topological properties of the Russian stock market using market graph, hierarchical tree, minimum spanning tree approaches. We compare topological properties of the networks constructed for the US and China stock markets with the properties of corresponding networks constructed for the Russian stock market using a dataset spanning over eight years.

Thermal tides in Martian atmosphere from ACS/TIRVIM Siteng Fan1 (sfan@lmd.ipsl.fr), Sandrine Guerlet1, Francois Forget1, Antoine Bierjon1, Ehouarn Millour1, Nikolay Ignatiev2, Alexey Shakun2, Alexey Grigoriev2, Alexander Trokhimovskiy2, Franck Montmessin3, Oleg Korablev2 1: LMD/IPSL, Sorbonne Université, PSL Research University, École Normale Supérieure, École Polytechnique, CNRS, Paris, France 2: Space Research Institute (IKI), Moscow, Russia 3: LATMOS/IPSL, Guyancourt, France Abstract Atmospheric thermal tides are planetary-scale temperature oscillations driven by diurnal solar forcing. On Mars, they dominate the temperature variations and winds throughout the thin atmosphere due to its low heat capacity. Given the short timescales of tide modes, which are typically equal or shorter than a Martian day, analyses of these tides require observations with large spatial coverage and high local time resolution. Observations from the TIRVIM Fourier-spectrometer, part of the Atmospheric Chemistry Suite (ACS) onboard ExoMars Trace Gas Orbiter (TGO), provide data meeting such requirement. Here we report the spatial- and temporal-dependent temperature profiles of Martian atmosphere retrieved from TIRVIM nadir data. Amplitudes and phases of thermal tide modes are obtained, and their influence on the thermal structure of Martian atmosphere is estimated using numerical simulations, The LMD Mars Global Circulation Model (GCM). Introduction Diurnal thermal forcing by solar radiation excites temperature oscillations in Martian atmosphere through direct sunlight absorption and heat exchange with Mars surface (Gierasch & Goody 1968). Influenced by surface topography, the varying solar forcing produces harmonic responses in the Martian atmosphere, thermal tides (Zurek 1976). Some modes of the tides can vertically propagate to upper altitudes with amplitudes growing exponentially with decreasing air density, which therefore influences the atmospheric circulation. The existence of such temperature and the related pressure variations has been observed by many Mars landers and orbiters (e.g., Hess et al., 1977, Banfield et al. 2000, Lee et al. 2009, Kleinböhl et al. 2013, Forbes et al. 2020), but observations are still lacking for comprehensive studies as large spatial coverage and high temporal resolution are required to study such planetary-scale diurnal/sub-diurnal variations. Methodology and Results We analyze the thermal tides using temperature structures retrieved from TIRVIM nadir data. TIRVIM is a thermal infrared Fourier-spectrometer, as part of the ACS instrument onboard the ESA-Roscosmos mission ExoMars TGO (Korablev et al., 2018, Svedhem et al. 2020). TGO is on a non-solar-synchronous orbit with a period of 2 hours, so observations obtained at nadir viewing geometry could cover a wide range of local time due to the short orbital period and orbit drifting (Capderou & Forget, 2004, Figure 1). A full diurnal cycle can be sampled between 74°N and 74°S within ~55 solar days (sols), which is equivalent to ~30° in solar longitude (Ls). Binning data within this range results in data covering most local time in a specific Martian month with little seasonal variations. TIRVIM operated from April 2018 to December 2019, nearly one Martian year (MY) from MY34 Ls134° to MY35 Ls 115°, and provides ~1.5 million thermal infrared nadir-viewing spectra with decent data quality. Despite some degeneracy, we retrieved temperature profiles together with dust and water ice from these spectra (Guerlet et al. 2018). Each profile covers a vertical range from ~2-3km above Mars surface to ~50-55km (~1-2Pa) with a vertical resolution of ~1 scale height (10km). Full coverage of local time is obtained for the first time on sub-seasonal scales (Figure 1), which makes it possible to evaluate thermal tides in Martian atmosphere with details and resolve the harmonic aliasing introduced by solar-synchronous observations, e.g., observations at 3am and 3pm local time by the Mars Climate Sounder (MCS, Lee et al. 2009). A preliminary result of the thermal structure on the Martian southern hemisphere near MY35 spring equinox (Ls=90°) is shown in Figure 2a. We binned the data between Ls 75° to 105° so that most of the local time is covered. No dust storms are identified during this period. The selected bin size of latitude is 3° and that of the local time is 1 hour. Temperature profiles are also zonal averages, so only migrating tides are shown. The diurnal temperature difference structure shows diurnal and semi-diurnal cycles at lower and middle atmosphere, respectively, with “apparent” amplitudes of ~7K. Due to the degeneracy introduced by vertically distributed sensitivity response functions of TIRVIM thermal infrared spectra, the retrieved temperature profiles are vertically smoothed (Guerlet et al. 2018). Suggested by the LMD Mars GCM (Forget et al. 1999), amplitudes of these tides are 2-3 times larger (Figure 2b), as smoothing them with the same response functions gives similar diurnal temperature difference structure (Figure 2c). A priori in the temperature profile retrieval makes a difference in extracting the diurnal temperature anomaly at low pressure level due to small weights in the convolution kernels (Figure 2b and 2c), which requires further investigation with GCMs. Figure 1. Spatial-temporal coverage of ACS/TIRVIM observations. Data from 20 orbits are shown for the purpose of illustration, with colors denoting the local time. Figure 2. (a) Diurnal temperature anomaly derived using ACS/TIRVIM observations. The data is binned between MY35 Ls 75° and 105°, and between 10.5°S and 13.5°S in latitude. (b) Result of the LMD Mars GCM. The model result has the same spatial-temporal sampling weight as observations. (c) Same as (b), but vertically convolved with the averaging kernels of TIRVIM. References Banfield, D., Conrath, B., Pearl, J. C., et al. (2000). JGR, 105, 9521. Capderou, M., & Forget, F. (2004). P&SS, 52, 789. Forbes, J. M., Zhang, X., Forget, F., et al. (2020). JGR: Space Physics, 125, e28140. Forget, F., Hourdin, F., Fournier, R., et al. (1999). JGR, 104, 24155. Gierasch, P., & Goody, R. (1968). P&SS, 16, 615. Guerlet, S., Ignatiev, N., Fouchet, T., et al. (2018). EPSC, 2018-223. Hess, S. L., Henry, R. M., Leovy, C. B., et al. (1977). JGR, 82, 4559. KleinböHl, A., John Wilson, R., Kass, D., et al. (2013). GRL, 40, 1952. Korablev, O., Montmessin, F., Trokhimovskiy, A., et al. (2018). SSW, 214, 7. Lee, C., Lawson, W. G., Richardson, M. I., et al. (2009). JGR: Planets, 114, E03005. Svedhem, H., Korablev, O., Mitrofanov, I., et al. (2020). EPSC, 2020-802. Zurek, R. W. (1976). JAS, 33, 321.

Many empirical studies have shown that in social, citation, collaboration, and other types of networks in real world, the degree of almost every node is less than the average degree of its neighbors. This imbalance is well known in sociology as the friendship paradox and states that your friends are more popular than you on average. If we introduce a value equal to the ratio of the average degree of the neighbors for a certain node to the degree of this node (which is called the ‘friendship index’, FI), then the FI value of more than 1 for most nodes indicates the presence of the friendship paradox in the network. In this paper, we study the behavior of the FI over time for networks generated by growth network models. We will focus our analysis on two models based on the use of the preferential attachment mechanism: the Barabási–Albert model and the triadic closure model. Using the mean-field approach, we obtain differential equations describing the dynamics of changes in the FI over time, and accordingly, after obtaining their solutions, we find the expected values of this index over iterations. The results show that the values of FI are decreasing over time for all nodes in both models. However, for networks constructed in accordance with the triadic closure model, this decrease occurs at a much slower rate than for the Barabási–Albert graphs. In addition, we analyze several real-world networks and show that their FI distributions follow a power law. We show that both the Barabási–Albert and the triadic closure networks exhibit the same behavior. However, for networks based on the triadic closure model, the distributions of FI are more heavy-tailed and, in this sense, are closer to the distributions for real networks.

This article takes an approach to creating a machine learning model for the oil and gas industry. This task is dedicated to the most up-to-date issues of machine learning and artificial intelligence. One of the goals of this research was to build a model to predict the possible risks arising in the process of drilling wells. Drilling of wells for oil and gas production is a highly complex and expensive part of reservoir development. Thus, together with injury prevention, there is a goal to save cost expenditures on downtime and repair of drilling equipment. Nowadays, companies have begun to look for ways to improve the efficiency of drilling and minimize non-production time with the help of new technologies. To support decisions in a narrow time frame, it is valuable to have an early warning system. Such a decision support system will help an engineer to intervene in the drilling process and prevent high expenses of unproductive time and equipment repair due to a problem. This work describes a comparison of machine learning algorithms for anomaly detection during well drilling. In particular, machine learning algorithms will make it possible to make decisions when determining the geometry of the grid of wells—the nature of the relative position of production and injection wells at the production facility. Development systems are most often subdivided into the following: placement of wells along a symmetric grid, and placement of wells along a non-symmetric grid (mainly in rows). The tested models classify drilling problems based on historical data from previously drilled wells. To validate anomaly detection algorithms, we used historical logs of drilling problems for 67 wells at a large brownfield in Siberia, Russia. Wells with problems were selected and analyzed. It should be noted that out of the 67 wells, 20 wells were drilled without expenses for unproductive time. The experiential results illustrate that a model based on gradient boosting can classify the complications in the drilling process better than other models.

Drilling of wells for oil and gas production is a highly complex and expensive part of reservoir development. Thus, together with injury prevention, there is a goal to save cost expenditures on downtime and repair of drilling equipment. Nowadays companies have begun to look for ways to improve the efficiency of drilling and minimize non-production time with the help of new technologies. To support decisions in a narrow time frame, it is valuable to have an early warning system. Such a decision support system will help an engineer to intervene in the drilling process and prevent high expenses of unproductive time and equipment repair due to a problem. This work is describing a comparison of machine learning algorithms for anomaly detection during well drilling. Tested models classify drilling problems based on historical data from previously drilled wells. To validate anomaly detection algorithms, we use historical logs of drilling problems for 67 wells at a large brownfield in Siberia, Russia. Wells with problems were selected and analyzed. It should be noted that out of the 67 wells, 20 wells were drilled without expenses for unproductive time. Experiential results illustrated that a model based on gradient boosting can classify the complications in the drilling process best of all.

International audience; Carbon monoxide (CO) is the main product of CO2 photolysis in the Martian atmosphere. Production of CO is balanced by its loss reaction with OH, which recycles CO into CO2. CO is therefore a sensitive tracer of the OH-catalysed chemistry that contributes to the stability of CO2 in the atmosphere of Mars. To date, CO has been measured only in terms of vertically integrated column abundances, and the upper atmosphere, where CO is produced, is largely unconstrained by observations. Here we report verti- cal profiles of CO from 10 to 120 km, and from a broad range of latitudes, inferred from the Atmospheric Chemistry Suite on board the ExoMars Trace Gas Orbiter. At solar longitudes 164–190°, we observe an equatorial CO mixing ratio of ~1,000 ppmv (10–80 km), increasing towards the polar regions to more than 3,000 ppmv under the influence of downward transport of CO from the upper atmosphere, providing a view of the Hadley cell circulation at Mars’s equinox. Observations also cover the 2018 global dust storm, during which we observe a prominent depletion in the CO mixing ratio up to 100 km. This is indicative of increased CO oxidation in a context of unusually large high-altitude water vapour, boosting OH abundance.

Carbon dioxide is the major constituent of the Martian atmosphere. Its seasonal cycle plays an important role in atmospheric dynamics and climate. Formation of the polar CO2 frost deposits results in up to 30% of atmospheric pressure variations as well as in dramatic change in surface reflectance and emissivity. Another case of carbon dioxide condensation is formation of a CO2 clouds that are still poorly studied, despite the fact that they have been observed by a number of instruments [1−6] on the orbit of Mars.In this work, we will present first results of CO2 clouds observations from a combination of thermal-infrared (1.7−17 µm) and near-infrared (0.7-1.6 µm) spectra measured by TIRVIM and NIR instruments onboard the ExoMars Trace Gas Orbiter (TGO) in solar occultation geometry. These instruments are part of the Atmospheric Chemistry Suite (ACS), a set of three spectrometers (NIR, MIR, and TIRVIM) that is conducting scientific measurements on the orbit of Mars since the spring of 2018 [7].This work was funded by Russian Science Foundation, grant number 20-42-09035.References[1] Montmessin et al. (2006). Subvisible CO2 ice clouds detected in the mesosphere of Mars. Icarus, 183, 403–410. https://doi.org/10.1016/j.icarus.2006.03.015[2] Montmessin et al. (2007). Hyperspectral imaging of convective CO2 ice clouds in the equatorial mesosphere of Mars. Journal of Geophysical Research, 112, E11S90. https://doi.org/10.1029/2007JE002944[3] Määttänen et al. (2010). Mapping the mesospheric CO2 clouds on Mars: MEx/OMEGA and MEx/HRSC observations and challenges for atmospheric models. Icarus, 209, 452–469. https://doi.org/10.1016/j.icarus.2010.05.017[4] McConnochie et al. (2010). THEMIS-VIS observations of clouds in the Martian mesosphere: Altitudes, wind speeds, and decameter-scale morphology. Icarus, 210, 545–565. https://doi.org/10.1016/j.icarus.2010.07.021[5] Vincendon et al. (2011). New near-IR observations of mesospheric CO2 and H2O clouds on Mars. Journal of Geophysical Research, 116, E00J02. https://doi.org/10.1029/2011JE003827[6] Jiang et al., (2019). Detection of Mesospheric CO 2 Ice Clouds on Mars in Southern Summer. Geophysical Research Letters, 46(14), 7962–7971. https://doi.org/10.1029/2019GL082029[7] Korablev et al., (2018). The Atmospheric Chemistry Suite (ACS) of three spectrometers for the ExoMars 2016 Trace Gas Orbiter. Space Sci. Rev. 214, 7. doi:10.1007/s11214-017-0437-6

The triadic closure model attempts to reflect the well-known fact that many real-world networks have a much higher likelihood of a link between a pair of nodes with a common neighbor than in the random null model. The effect is especially evident in social networks and is also widely present in cooperation networks in the field of knowledge, citation and research, and many others. It should be noted that in the triadic closure model proposed by P. Holme and B.J. Kim, at the triad formation step, the new link is attached to any random neighbor (which is chosen evenly) of the node selected in the previous step (which is chosen using the preferential attachment mechanism). However, in many real-world complex networks, the second link is also usually selected using the preferential attachment mechanism. In this paper, we propose to make adjustments to the triadic closure model for the case when the nodes are selected using the preferential attachment mechanism at the triad formation step. We empirically investigate the dynamics of the mean value of node degree in the networks generated by this model and show that it follows a power law.

Cool stars, especially spectral-type M, are important probes across contemporary astrophysics, from the forma- tion history of the galaxy to the coalescence of rocky exoplanets. Main sequence M-dwarf stars are one of the most abundant stars in the galaxy, and evolved M-giant stars are some of the most distant stars that can be individually observed. The Emu sky survey, described here, will deliver critical stellar properties of these cool stars by inferring the oxygen abundance via measurement of the water band strength at 1.4 μm. A relatively wide field zenith-looking telescope with time delay integration capability can perform such a survey without active pointing but requires a fast and low-noise detector. Emu employs the paradigm-changing properties of the Leonardo SAPHIRA electron avalanche photodiode array, to provide these powerful new observations at the critical water absorption wavelength inaccessible to ground-based telescopes due to the Earth's own atmosphere. Here we will present Emu mission concept, science objectives, instrument details and simulation results.

The ExoMars Trace Gas Orbiter (TGO) mission was sent to Mars in 2016 to make the most sensitive measurements of the atmosphere to date and to hunt for any trace gases diagnostic of active geologic or biogenic processes (Vago et al., 2015). After the first full Mars year of observations, we are able to report the first such discovery: gaseous hydrogen chloride (HCl) has been detected by the Atmospheric Chemistry Suite mid-infrared channel (ACS MIR). ACS science operations commenced at a crucial time for Mars observations. The first solar occultation spectra were recorded on solar longitude (Ls) 163 (late April 2018) at a time of changing seasons on Mars. The northern hemisphere was entering winter, while the southern hemisphere was beginning to warm towards summer season. Around Ls 190, we witnessed a global dust storm of unprecedented severity, with dust remaining in the atmosphere through Ls 250 (Montabone et al., 2020). HCl was observed by ACS simultaneously in both hemispheres after the main phase of the global dust storm. It remained detectable to ACS MIR for several months, while the impact of the dust was still being felt in the atmosphere, before vanishing. The dust lofted and mixed into the atmosphere caused the atmosphere to warm resulting in an expansion of the lowest layers, increasing the water vapour content, elevating the hygropause to 50-60 km, and enhancing meridional Hadley cell circulation (Fedorova et al., 2020). Fig. 1 shows a model of the absorption spectrum contributions of the Martian atmosphere as seen by ACS MIR. The HCl branches, shown in the lower panel, partially overlap with the region of interest used to investigate methane (CH4). So far, TGO instruments have found no evidence of the absorption signature of methane, but in its place ACS MIR has made two surprising discoveries: we have identified a previously unknown CO2 absorption-rotation band (Trokhimovskiy et al., 2020); and we were able to resolve the spectral signature of ozone at low altitudes in the north polar region at the start of norther winter (Olsen et al., 2020a). Methods ACS MIR is a cross-dispersion spectrometer operating in solar occultation mode (Korablev et al., 2018). This geometry provides high signal-to-noise ratios, excellent sensitivity to the vertical structure of the atmosphere, and a very long optical path, amplifying trace gas absorption. The instrument consists of a primary echelle diffraction grating to disperse infrared radiation, followed by a secondary, steerable diffraction grating to separate diffraction orders. The secondary grating position changes the instantaneous spectral range. The full coverage is 2300-4500 cm-1, and the spectral resolution achieved is 0.040-0.045 cm-1 in the region of interest for HCl. The spectral range shown in Fig. 1 covers two secondary grating positions, labelled 11 and 12. Fig. 1. Modelled gas absorption contributions as seen in the lower atmsophere by ACS MIR during solar occultation. The top panel shows contributions from major species: CO2, H2O, and HDO. The bottom panel shows contributions from HCl at 1.5 ppbv, ozone at 140 ppbv, and methane at 1 ppbv. HCl and O3 signatures at these mixing ratios have been observed, while CH4 has not. Spectral fitting was done using the JPL Gas Fitting Software Suite (GFIT) (Irion et al., 2002; e.g., Sen et al., 1996). GFIT computes volume mixing ratio scaling factors for each spectral window and at each altitude. A retrieved profile of gas abundance is derived by inverting the matrices of optical paths and the estimated column abundances. Temperature and pressure profiles are retrieved from coincident observations made with the ACS near infrared channel (ACS NIR) (Fedorova et al., 2020; Vandaele et al., 2019). A full description of the retrieval method can be found in (Olsen et al., 2020b). References Fedorova, A. A., et al.: Stormy water on Mars: The distribution and saturation of atmospheric water during the dusty season, Science, 367(6475), 297–300, doi:10.1126/science.aay9522, 2020. Irion, F. W., et al.: Atmospheric Trace Molecule Spectroscopy (ATMOS) Experiment Version 3 data retrievals, Appl. Opt., 41, 6968–6979, doi:10.1364/AO.41.006968, 2002. Korablev, O., et al.: The Atmospheric Chemistry Suite (ACS) of Three Spectrometers for the ExoMars 2016 Trace Gas Orbiter, Space. Sci. Rev., 214(1), 7, doi:10.1007/s11214-017-0437-6, 2018. Montabone, L., Spiga, A., Kass, D. M., Kleinböhl, A., Forget, F. and Millour, E.: Martian Year 34 Column Dust Climatology from Mars Climate Sounder Observations: Reconstructed Maps and Model Simulations, J. Geophys. Res., 2020. Olsen, K. S., et al.: First detection of ozone in the mid-infrared at Mars: implications for methane detection, Astron. Astrophys. in press, doi:10.1051/0004-6361/202038125, 2020a. Olsen, K. S., et al.: The vertical structure of CO in the Martian atmosphere as observed by ACS on ExoMars TGO, Nat. Geosci. submitted, 2020b. Sen, B., Toon, G. C., Blavier, J.-F., Fleming, E. L. and Jackman, C. H.: Balloon-borne observations of midlatitude fluorine abundance, J. Geophys. Res., 101, 9045–9054, doi:10.1029/96JD00227, 1996. Trokhimovskiy, A., Perevalov, V., Korablev, O., Fedorova, A. F., Olsen, K. . S., Bertaux, J.-L., Patrakeev, A., Shakun, A. and Montmessin, F.: First observation of the magnetic dipole CO₂ main isotopologue absorption band at 3.3 μm in the atmosphere of Mars by ACS, Astron. Astrophys. in press, doi:10.1051/0004-6361/202038134, 2020. Vago, J., Witasse, O., Svedhem, H., Baglioni, P., Haldemann, A., Gianfiglio, G., Blancquaert, T., McCoy, D. and de Groot, R.: ESA ExoMars program: The next step in exploring Mars, Sol. Syst. Res., 49(7), 518–528, doi:10.1134/S0038094615070199, 2015. Vandaele, A. C., et al., the NOMAD Science Team and ACS Science Team: Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter, Nature, 568, 521–525, doi:10.1038/s41586-019-1097-3, 2019.

We report retrievals in the 2.53 – 2.79 μm spectral range using the Atmopheric Chemistry Suite onboard of ExoMars Trace Gas Orbiter, which allow the simultaneous measurement of vertical profiles of H and O isotope ratios in water vapour in the Martian atmosphere. The large coverage of ACS MIR solar occultations provides the possibility to analyse the spatial, seasonal and diurnal variations of these ratios. 1. Introduction Isotopic ratios in C, O and H provide important clues to understand the history and evolution of volatiles on Mars. Enrichment of the D/H ratio by a factor of approximately 5.5 in atmospheric water vapour with respect to the Vienna Standard Mean Ocean Water [1] has often been understood as evidence of the substantial atmospheric escape into space. On the other hand, oxygen isotope ratios in both water vapour and carbon dioxide do not show substantial enrichment of the heavier isotopes (e.g. [2],[3]). The lack of substantial fractionation therefore indicates the presence of a large reservoir of oxygen to exchange with the atmosphere [4]. In this work, we use solar occultation measurements made with the mid-infrared (MIR) channel of the Atmospheric Chemistry Suite (ACS), onboard ExoMars Trace Gas Orbiter (TGO) to measure the evolution of the vertical structure of the isotopic composition of water vapour (D/H, 18O/16O and 17O/16O) at the terminator for a full Martian year. 2. Measurements ACS consists of a set of three infrared spectrometers covering a total wavelength range from 0.7 to 17 μm. The MIR channel, used in this study, is a cross-dispersion echelle spectrometer dedicated to solar occultation measurements in the 2.3-4.2 μm (2300-4400 cm-1) range, with the main objective of measuring high resolution spectra (λ/Δλ∼30000-50000) in a wide instantaneous spectral range (width 0.15-0.3 μm). In order to cover the full spectral range, MIR is equipped with a steerable secondary grating that allows the selection of different diffraction orders [5]. In this work, we analyse MIR spectra in secondary grating positions 4 and 5, which allow the simultaneous measurement of several diffraction orders covering a spectral range from 2.67 to 2.79 μm (3584-3745 cm-1) and 2.53 to 2.67 μm (3745-3952 cm-1), respectively. We select spectral windows in several diffraction orders, which show absorption lines of the four main oxygen isotopologues of water vapour (H216O, H218O, H217O, HD16O) and CO2 (see Figure 1). Figure 1: Example of one ACS MIR spectral window in diffraction order 224, measured at tangent heights of 19, 35 and 50 km. The black dots represent the measured spectra, and the green line shows the best fit to the data. The contribution from each species to the spectra is also shown, following the colours in the legend. 3. Radiative Transfer Analysis The analysis of the spectra is performed using the NEMESIS code [6], which works under the optimal estimation framework. In particular, for each solar occultation, we retrieve simultaneous vertical profiles of pressure, temperature and volume mixing ratio of the four main water isotopologues. The pressure and temperature profiles can be constrained from the CO2 absorption lines under the assumption of hydrostatic equilibrium and a given CO2 volume mixing ratio profile, which we obtain from the Mars Climate Database [7]. In the case of the water vapour isotopologues, the volume mixing ratios can be constrained from the depth of the corresponding absorption lines, which are observed up to 60 km approximately. The retrieval scheme is applied to all ACS MIR observations made with secondary grating positions 4 and 5 for a full Martian year, covering a wide range of latitudes, seasons, and local time, and enabling, for the first time, the study of the climatology of both the O and H isotopic ratios in Martian water vapour. 4. Summary and Conclusions Vertical profiles of the isotope ratios in the four main water vapour isotopologues (D/H, 18O/16O and 17O/16O) at the terminator are obtained using solar occultation measurements by the Atmospheric Chemistry Suite onboard ExoMars Trace Gas Orbiter. The large coverage of ACS solar occultation measurements allows, for the first time, the analysis of the variations of the O and H isotopic composition of water vapour for a full Martian year. References [1] Owen, T., Maillard, J. P., de Bergh, C., and Lutz, B. L..: Deuterium on Mars: The abundance of HDO and the values of D/H, Science, 240, 1767 LP - 1767, 1988. [2] Webster, C. R., Mahaffy, P. R., Flesch, G. J., Niles, P. B., Jones, J. H., Leshin, L. A., Atreya, S. K., Stern, J. C., Chrsitensen, L. E., Owen, T., Franz, H., Pepin, R. O., and Steele, A.: Isotope Ratios of H, C and O in CO2 and H2O of the Martian Atmosphere, Science, 341, 260 LP – 263, 2013. [3] Krasnopolsky, V.A., Maillard, J. P., Owen, T., Toth, R. A., Smith, M. D.: Oxygen and carbon isotope ratios in the martian atmosphere, Icarus, Vol. 192, Issue 2, 2007. [4] Jakosky, B. M.: Mars Volatile Evolution: Evidence from Stable Isotopes, Icarus, 94, 14-31, 1991. [5] Korablev et al.: The Atmospheric Chemistry Suite (ACS) of Three Spectrometers for the ExoMars 2016 Trace Gas Orbiter, Space Science Reviews, vol. 214, pag. 7, 2017. [6] Irwin, P., Teanby, N., de Kok, R., Fletcher, L., Howett, C., Tsang, C., Wilson, C., Calcutt, S., Nixon, C., Parrish, P.: The NEMESIS planetary atmosphere radiative transfer and retrieval tool, Journal of Quantitative Spectroscopy and Radiative Transfer,109, 1136-1150. [7] Forget, F., Hourdin, F., Fournier, R., Hourdin, C., Talagrand, O., Collins, M., Lewis, S. R., Read, P. L., and Huot, J-P: Improved general circulation models of the Martian atmosphere from the surface to above 80 km, Journal of Geophysical Research: Planets, 104, 24155-24175, 1999.

ESA’s ExoMars program comprises two missions including the Trace Gas Orbiter (TGO), launched in 2016, and a rover and surface platform, to be launched in 2022. The main scientific objectives of the program are to investigate the Martian environment and climate and search for past or present signs of life. For this purpose, a suite of three infrared spectrometers for remote sensing (Atmospheric Chemistry Suite, ACS) is in use on TGO. One of these instruments is a Fourier transform spectrometer, TIRVIM (Thermal IR V-shape Interferometer Mounting in honor of Vassili Ivanovich Moroz), operating in nadir, limb or solar occultation mode between 1.7 and 17 μm. On ExoMars22’s surface platform the spectrometer FAST (Fourier for Atmospheric Species and Temperature) will study the atmosphere and surface at the landing site in the same wavelength range as TIRVIM on TGO. This paper presents the objectives of TIRVIM and FAST. It summarizes selected results of the determination of temperature profiles and dust content in the lower atmosphere of Mars based on radiative transfer modeling of TIRVIM data. Synergetic analyses of TIRVIM spectra and InSight (NASA) in situ measurements of temperature and pressure at InSight’s landing site in Elysium Planitia enable improvements of procedures to retrieve parameters from TIRVIM observations. First results on surface temperature obtained from these different data sets together with the measurements to be expected in the future from FAST offer a unique opportunity to compare in situ and IR remote sensing measurements.

Background: Urinary tract infections (UTIs) are common in women, and during pregnancy can cause significant morbidity. Growing and greatly varying antimicrobial resistance (AMR) of Enterobacteriaceae, responsible for most UTIs, necessitates regular local AMR surveillance. In obstetric population, where beta-lactams are the mainstay for treatment of severe UTIs, particular focus should be placed on beta-lactam resistance. This study aimed to evaluate AMR rates and frequency of extended spectrum beta-lactamase (ESBL) and carbapenemase genes in uropathogenic Enterobacteriaceae among reproductive-age women in St. Petersburg, Russia.Materials/methods: Urine samples were collected from consecutive reproductive-age women, who attended the D.O. Ott Research Institute of Obstetrics, Gynecology and Reproductology from October 2017 to November 2019, and cultured according to routine procedures. Susceptibility to antibiotics and ESBL production was determined using the disc diffusion method according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. All urine samples and Enterobacteriaceae isolates were tested for ESBL and carbapenemase genes using real-time PCR.Results: Enterobacteriaceae were detected in 91 (56 pregnant and 35 non-pregnant) of 119 (76%) included women. The vast majority of Enterobacteriaceae strains were susceptible to nitrofurantoin, fosfomycin and meropenem (99-100%). The frequency of strains susceptible to penicillins and cephalosporins ranged from 59% to 82%; 78% of strains were susceptible to ciprofloxacin. ESBL production was phenotypically detected in 15 (16%) Enterobacteriaceae strains, with CTX-M genes revealed in all cases. In all corresponding urine samples, CTX-M genes were also detected. The remaining 104 urine samples were negative for CTX-M genes. In none of the isolates and urine samples, carbapenemase genes were present.Conclusions: The frequency of ESBL producing Enterobacteriaceae was relatively high (16%), with CTX-M genes detected in all cases in both urine and urine cultures. Rapid PCR detection of CTX-M genes directly in urine samples from women with pyelonephritis can be valuable for timely informing treatment choices.

Water reaches Mars' upper atmosphere Mars once hosted abundant water on its surface but subsequently lost most of it to space. Small amounts of water vapor are still present in the atmosphere, which can escape if they reach sufficiently high altitudes. Fedorova et al. used data from the ExoMars Trace Gas Orbiter spacecraft to determine the distribution of water in Mars' atmosphere and investigate how it varies over seasons. Water vapor is sometimes heavily saturated, and its distribution is affected by the planet's large dust storms. Water can efficiently reach the upper atmosphere when Mars is in the warmest part of its orbit, and this behavior may have controlled the overall rate at which Mars lost its water. Science , this issue p. 297

International audience; The properties of Martian aerosols are an integral part of the planetary climatology. Global dust storms (GDS) significantly alter spatial and vertical distributions of dust and water ice aerosols and their microphysical properties. We explored the 2018/Martian Year 34 GDS with the Atmospheric Chemistry Suite (ACS) instrument onboard the ESA‐Roscosmos Trace Gas Orbiter (TGO) mission. Solar occultation observations of Thermal InfraRed (TIRVIM) and Near InfraRed (NIR) channels in the 0.7−6 μm spectral range with >103 signal‐to‐noise ratio are used to constrain the vertical dependence and the temporal evolution of the particle properties of water ice and dust (effective radius, effective variances, number density, and mass loading) before the 2018 GDS and during its onset and decay phases. In most of the observations, the particle size of dust and water ice decreases with altitude. The effective radius of dust and water ice particles ranges from 0.1−3.5 μm and 0.1−5.5 μm, respectively. The largest aerosol particles (> 2.5 μm for dust and > 3.5 μm for water ice) are present below 10 km before the onset and during the GDS decay phase. During the peak of the GDS, dust reached altitudes of 85 km; the most frequently observed effective radius is 1−2 μm with 0.1−1 cm‐3 number density and 0.1 effective variance. Detached layers of water ice composed of 0.1−1 μm particles are systematically observed at 50−100 km during this period. Below, at 0−50 km, we see the dust mixed with the main water ice layer comprising 1−4 μm particles.

In planetary research, Fourier transform infrared spectrometers (FTIR) solve a number of important scientific goals related both to the atmosphere and to the surface sounding. For remote orbital measurements, these goals are the thermal sounding of the atmosphere using, in particular, the 15-µm CO2 band, sensitive detections of minor gaseous species and aerosol characterization. FTIR can address similar atmospheric science goals when observing from a planetary surface allowing for better-resolved boundary layer and achieving greater accuracy (longer integration) for minor species detection. For studies of planetary surfaces, characterization of mineralogical composition in a wide IR range including sensitive measurements of hydration of the soil on airless bodies can be done. We outline a family of FTIR instruments dedicated to studies of Mars and the Moon. TIRVIM is a channel of ACS on ExoMars TGO (in orbit around Mars since October 2016). It is a 2-inch interferometer for nadir and solar occultation measurements of Mars’ atmosphere. It covers a spectral range of 1.7–17 µm with spectral resolution up to 0.13 cm−1. LUMIS is a similar instrument for Luna-Resource Orbiter (Luna-26) Roscosmos mission dedicated to the search for hydration of the lunar regolith in the 6-µm band. The spectral range of LUMIS is broad (1.7–17 µm), but its sensitivity is optimized for the 4–8 µm region. The spectral resolution is 50 cm−1. We also describe recent developments focused on technical solutions for miniaturized FTIR instruments with a very high spectral resolution (0.05 cm−1 and higher). The prototype targets measurements of minor atmospheric species from the surface of Mars using the Sun tracking. One important task is to provide a high precision of interferometer’s mirror movement. Another task is the development of a precise two-coordinate mechanism to seek for and follow the Sun.

Oxygen isotope ratios provide important constraints on the history of the Martian volatile system, revealing the impact of several processes that might fractionate them, such as atmospheric loss into space or interaction with the surface. We report infrared measurements of the Martian atmosphere obtained with the mid-infrared channel (MIR) of the Atmospheric Chemistry Suite (ACS), onboard the ExoMars Trace Gas Orbiter. Absorption lines of the three main oxygen isotopologues of water vapour (H216O, H218O, and H217O) observed in the transmission spectra allow, for the first time, the measurement of vertical profiles of the 18O/16O and 17O/16O ratios in atmospheric water vapour. The observed ratios are enriched with respect to Earth-like values (δ18O = 200 ± 80‰ and δ17O = 230 ± 110‰ corresponding to the Vienna Standard Mean Ocean Water). The vertical structure of these ratios does not appear to show significant evidence of altitudinal variations.

We describe a 1-inch aperture pointing system realized with a rope transmission driven by geared stepper motors for operation at the surface of Mars. The system is intended to serve in the Fourier-transform spectrometer to observe both the sun through the atmosphere and the thermal emission of the atmosphere. The scanner covers a full 2π field of view (the upper hemisphere). The accuracy of 0.1 mrad (~21 arcsec) for the sun tracking is achieved using an automatic control system with an IR array sensor (32x32) in the loop. The optics of the pointing system consists of three flat mirrors and a germanium inlet window. The mass of the subsystem does not exceed 0.8 kg. The design accounts for the necessity of dust protection in the Martian environment. The effect of a finite accuracy of the pointing and tracking on the instrument signal to noise ratio is modeled.

An interferometer is an essential subsystem of the Fourier-transform spectrometer (FTS). We describe an FTS instrument to operate at the surface of Mars based on a Michelson interferometer with hollow retroreflectors. The instrument will operate in two different regimes, observing the solar disc through the atmosphere to measure trace gases, and measuring the thermal emission from the atmosphere to study the planetary boundary layer (PBL). The interferometer has an aperture of 1 inch, operates in the spectral range 1.7-17 μm, and features low mass and volume (≤1 kg with all necessary subsystems). Beam splitter and compensator are made of potassium bromide (KBr). A single-axis robot with stepper motor drive provides a linear movement of the retroreflector (the speed stability is about 2%) and enables a maximal optical path difference (MOPD) of 15 cm. A reference channel with a distributed-feedback laser diode (0.76 μm) and a photodiode (Si) supports the interferogram sampling and the speed stabilization loop. The time to measure one interferogram with a best spectral resolution of about 0.05 cm–1 is 500 s (the sun tracking regime). In the thermal sounding regime, one measurement of a two-side interferogram (with the spectral resolution of ~1 cm–1) takes less than 1 min. Laboratory calibrations with a black body and a laser confirm the design parameters of the instrument.

In this paper we study some properties of the Russian stock market with the application of network approaches and data-driven science. Complex networks theory allows us to construct and analyse topological network structures of the market. Among the important information which is possible to acquire from it is the relationships between stocks returns with the analysis of hidden information and market dynamics. This paper is focused on the analysis of the market network dynamics over time. We construct market networks for 75 consecutive overlapping 250-day periods to analyze the dynamics of the structural properties of the market rank-correlation-based network. Degree distribution and maximum clique size are considered as the important structural characteristics of the market network. In our opinion these parameters are the essential graph attributes and give insight into Russian financial market structure.

Atmospheric Chemistry Suite (ACS) is a part of Russian contribution to ExoMars Trace Gas Orbiter (TGO) ESA-Roscosmos mission. ACS includes three separate infrared spectrometers (MIR, NIR and TIRVIM) with a different spectral coverage and targeted to the different science goals. ACS TIRVIM is a Fourier-transform spectrometer based on 2-inch double pendulum interferometer. It operates in the spectral range of 1.7-7 μm with the best spectral resolution 0.13 cm-1 for solar occultation (SO) mode and 0.8 cm-1 for nadir mode. In nadir mode TIRVIM is purposed to thermal sounding of the Martian atmosphere and aerosol properties retrieval. In SO mode TIRVIM is dedicated to trace gases measurements complementing to ACS MIR. After successful launch of ExoMars TGO on 16 April 2016 there were three time slots for turning on science instruments during cruise phase to execute necessary checks and calibration measurements. In March 2018 the nominal science orbit was reached after cruise and aerobraking phases. The first results of TIRVIM data processing show high performance of the instrument.

The aim of the paper is to provide an analysis of news and financial data using their network representation. The formation of network structures from data sources is carried out using two different approaches: by building the so-called market graph in which nodes represent financial assets (e.g., stocks) and the edges between nodes stand for the correlation between the corresponding assets, by constructing a company co-mention network in which any two companies are connected by an edge if a news item mentioning both companies has been published in a certain period of time. Topological changes of the networks over the period 2005&ndash, 2010 are investigated using the sliding window of six-month duration. We study the stability of the market graph and the company co-mention network over time and establish which of the two networks was more stable during the period. In addition, we examine the impact of the crisis of 2008 on the stability of the market graph as well as the company co-mention network. The networks that are considered in this paper and that are the objects of our study (the market graph and the company co-mention network) have a non-changing set of nodes (companies), and can change over time by adding/removing links between these nodes. Different graph similarity measures are used to evaluate these changes. If a network is stable over time, a measure of similarity between two graphs constructed for two different time windows should be close to zero. If there was a sharp change between the graphs constructed for two adjacent periods, then this should lead to a sharp increase in the value of the similarity measure between these two graphs. This paper uses the graph similarity measures which were proposed relatively recently. In addition, to estimate how the networks evolve over time we exploit QAP (Quadratic Assignment Procedure). While there is a sufficient amount of works studying the dynamics of graphs (including the use of graph similarity metrics), in this paper the company co-mention network dynamics is examined both individually and in comparison with the dynamics of market graphs for the first time.

The surname of author Cathy Quantin-Nataf was misspelled ‘Quantin-Nata’, authors Ehouarn Millour and Roland Young were missing from the ACS and NOMAD Science Teams list, and minor changes have been made to the author and affiliation lists; see accompanying Amendment. These errors have been corrected online.

The surname of author Cathy Quantin-Nataf was misspelled ‘Quantin-Nata’ , authors Ehouarn Millour and Roland Young were missing from the ACS Science Team list, and minor changes have been made to the author and affiliation lists; see accompanying Amendment. These errors have been corrected online.

Observations of Mars with the infrared imaging spectrometer ISM on board the Phobos -2 spacecraft provided more than 40,000 spectra in the wavelength range 0.7–3.2 μm with a spatial resolution of about 20 km. These spectra bear features of both atmospheric and surface origin. Measurements in the water vapour bands near 1.9 and 2.6 μm along the flanks of huge Martian volcanoes provided the data on the H 2 O spatial variations above them. The retrieved mixing ratio was about 200 ppm above the volcanoes, which was about a factor of five higher than that found above the surrounding terrains. The origin of the observed water vapour anomaly is likely to be connected to the volcanoes and could be explained by the regolith-atmosphere water vapour exchange. On the basis of a new theoretical approach to the process of diffusion of adsorbed water from the regolith to the atmosphere, a model of the observed anomaly was proposed. It implies an intensive vapour desorption during the day hours from the volcanic regolith, which was assumed to be different in composition from that of surrounding highlands.

We discuss the results of measurements made with the Planetary Fourier Spectrometer (PFS) onboard the Mars Express spacecraft. The data were obtained in the beginning of the mission and correspond to the end of summer in the southern hemisphere of Mars (L s ∼ 340°). Three orbits are considered, two of which passed through volcanoes Olympus and Ascraeus Mons (the height above the surface is about +20 km), while the third orbit intersects lowland Hellas (−7 km). The influence of the relief on the properties of the aerosol observed is demonstrated: clouds of water ice with a visual optical thickness of 0.1–0.5 were observed above volcanoes, while only dust was found during the observations (close in time) along the orbit passing through Hellas in low and middle latitudes. This dust is homogeneously mixed with gas and has a reduced optical thickness of 0.25±0.05 (at v = 1100 cm−1). In addition to orographic clouds, ice clouds were observed in this season in the northern polar region. The clouds seen in the images obtained simultaneously by the mapping spectrometer OMEGA confirm the PFS results. Temperature inversion is discovered in the north polar hood below the level 1 mbar with a temperature maximum at about 0.6 mbar. This inversion is associated with descending movements in the Hadley cell.

International audience; The acousto-optic spectrometer of the near infrared range, which is a part of the spectrometer SPICAM onboard the Mars-Express spacecraft, began to operate in the orbit of Mars in January 2004. In the SPICAM experiment, a spectrometer on the basis of an acousto-optic filter was used for the first time to investigate other planets. During one and a half years of operation, the IR channel of SPICAM obtained more than half a million spectra in the 1-1.7 μm range with a resolving power of more than 1500 in different modes of observation: limb, nadir, and solar eclipses. The main goal of the experiment is to study the content of water vapor in the Martian atmosphere by measuring the absorption spectrum in the 1.38 μm band. Characteristics of the instrument (high spectral resolution and signal-to-noise ratio) allow one to solve a number of additional scientific problems including the study of ozone distribution by emission of singlet oxygen (O2 1Δg), detection of the water and carbonic dioxide ices, and also the study of the vertical distribution and optical characteristics of aerosol in the Martian atmosphere. We present a description of the instrument, the results of its ground and in-flight calibrations, and a brief survey of the basic scientific results obtained by the SPICAM spectrometer during a year-and-half of operation.

International audience; The SPICAM Light optical package on the ESA Mars Express mission is dedicated to the nadir and limb observations in the UV between 118 nm and 320 nm, and has originally included an IR solar occultation channel, an inheritance of the IR part of the SPICAM solar occultation instrument for Mars 96. Because of severe mass constrains of the mission this channel has been replaced by a lightweight (0.7 kg) near infrared instrument that employs a new technology acousto-optical tuneable filter (AOTF). This channel is dedicated to the nadir measurements of water vapour column abundance in the near infrared between 1 and 1.7 μm simultaneously with ozone measured in the UV. In addition to the measurements of water vapour column abundance in the band of 1.38 μm, the NIR nadir spectrometer will measure the CO2 quantity in the bands of 1.43, 1.57-1.6 μm, and, consequently, the surface pressure (with known topography); and will contribute to the studies of atmospheric aerosols and the surface, by spectro-polarimetry measurements. Fully functional model of the instrument has been assembled, has been undergone a number of tests; the spectra of terrestrial atmospheric transmittance have been recorded. The scientific context of the experiment will be discussed along with the instrument's description; current development status and the calibration results will be presented.

The infrared imaging spectrometer (ISM) on board Phobos-2 spacecraft provided the most important and valuable data on the atmospheric water content on Mars in the post-Viking period. Some of the results of this experiment are likely to be the evidence of the existence of the regolith-atmosphere water vapour exchange. Release of the water molecules, stored in the regolith in the adsorbed phase, to the atmosphere, induced by the noon temperature rise can cause up to a factor of 3 increase in the atmospheric water amount above the areas with high adsorbing capabilities such as clay regolith. Much less, about 30%, increase is expected above the terrains, covered with basalt grains. Local time variations of atmospheric water amount, observed by ISM, are within these limits. The dependence of water vapour desorption rate on the regolith properties can result in the spatial variations of atmospheric water content above clay and basalt regions. This is assumed to be the reason of a factor of 5±2 increase in the atmospheric water mixing ratio, observed by ISM above the flanks of Martian volcanoes as compared to the surrounding terrains.

The infrared instrument IKS flown on board the VEGA space probes was designed for the detection of emission bands of parent molecules, and for a measurement of the size and temperature of the thermal emitting nuclear region. The instrument had three channels with cooled detectors: an "imaging channel" designed to modulate the signal of the nucleus and two spectroscopic channels operating at 2.5-5 and 6-12 micrometers, respectively, equipped with circular variable filters of resolving power approximately 50. This paper presents and discusses the results from the spectral channels. On VEGA 1, usable spectra were obtained at distances D from the comet nucleus ranging from 250,000 to 40,000 km corresponding to fields of view 4000 and 700 km in diameter, respectively. The important internal background signal caused by the instrument itself, which could not be cooled, had to be eliminated. Since no sky chopping was performed, we obtain difference spectra between the current spectrum and a reference spectrum with little or no cometary signal taken at the beginning of the observing sequence (D approximately 200,000 km). Final discrimination between cometary signal and instrumental background is achieved using their different time evolution, since the instrumental background is proportional to the slow temperature drift of the instrument, and the cometary signal due to parent molecules or dust grains is expected to vary in first order as D-1. The 2.5-5 micrometers IKS spectra definitely show strong narrow signals at 2.7 and 4.25 micrometers, attributed to the nu 3 vibrational bands of H2O and CO2, respectively, and a broader signal in the region 3.2-3.5 micrometers, which may be attributed to CH-bearing molecules. All these signals present the expected D-1 intensity variation. Weaker emission features at 3.6 and 4.7 micrometers could correspond to the nu 1 and nu 5 bands of H2CO and the (1 - 0) band of CO, respectively. Molecular production rates are derived from the observed emissions, assuming that they are due to resonance fluorescence excited by the Sun's infrared radiation. For the strong bands of H2O and CO2, the rovibrational lines are optically thick, and radiative transfer is taken into account. We derive production rates, at the moment of the VEGA 1 flyby, of approximately 10(30) sec-1 for H2O, approximately 2.7 x 10(28) sec-1 for CO2, approximately 5 x 10(28) sec-1 for CO, and 4 x 10(28) sec-1 for H2CO, if attributions to CO and H2CO are correct. The production rate of carbon atoms in CH-bearing molecules is approximately 9 x 10(29) sec-1 assuming fluorescence of molecules in the gas phase, but could be much less if the 3.2-3.5 micrometers emission is attributed to C-H stretch in polycyclic aromatic hydrocarbons or small organic grains. In addition, marginal features are present at 4.85 and 4.45 micrometers, tentatively attributed to OCS and molecules with the CN group, respectively. Broad absorption at 2.8-3.0 micrometers, as well as a narrow emission at 3.15 micrometers, which follow well the D-1 intensity variation, might be due to water ice. Emission at 2.8 micrometers is also possibly present, and might be due to OH created in vibrationally excited states after water photodissociation. The 6-12 micrometers spectrum does not show any molecular emission, nor emission in the 7.5-micrometers region. The spectrum is dominated by silicate emission showing a double structure with maxima at 9.0 and 11.2 micrometers, which suggests the presence of olivine.