A comparison of multiple Rosetta data sets and 3D model calculations of 67P/Churyumov-Gerasimenko coma around equinox (May 2015)

We have used the latest available shape model for gas and dust simulations of the inner coma of comet 67P/Churyumov-Gerasimenko for the period around May 2015 (equinox). We compare results from a purely insolation-driven model with a complementary set of observations made by ROSINA, VIRTIS, MIRO, and OSIRIS within the same period. The observations include - for the first time - inverted MIRO measurements of gas density, temperature and bulk velocity to constrain the model. The comparisons show that, as in November 2014 (Marschall et al., 2016), insolation-driven activity does not provide an adequate fit to the data. Both VIRTIS and MIRO observations indicate that emissions from the Hatmehit and Imhotep regions of the nucleus are strongly depleted in total gas, H2O, and dust emissions in this case. The MIRO inversion provides a challenging constraint to the models as a consequence of the terminator orbit and nucleus pointing of the spacecraft. Nonetheless a consistent picture with a dominance of outgassing from the Hapi region, even at equinox, is clearly evident. An inhomogeneous model consistent with models proposed for the November 2014 time-frame was constructed and provides a better fit to the data. As far as we are aware this is the first time comae data from four Rosetta instruments have been used to constrain within one self-contained model the emission distribution at the nucleus surface and study the dynamics of the gas and dust outflow

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Dayside-to-nightside dust coma brightness asymmetry and its implications for nightside activity at Comet 67P/Churyumov–Gerasimenko

We have determined the dust coma brightness ratio between the dayside and the nightside (DS:NS) in OSIRISimages of comet 67P/Churyumov–Gerasimenko and compared them to results from numerical dust comasimulations to learn more about the dynamic processes that are involved in coma formation. The primaryfocus of this paper lies in the analysis of a subset of OSIRIS images acquired during one comet rotation on11. April 2015 when the spacecraft was at a phase angle of 90◦and therefore directly above the terminator.The DS:NS ratio was found to be 2.49±0.18 on average - a very low value if insolation-driven sublimation ofwater dominates dust emission. We investigated two possible hypotheses: First, the influence of direct activityfrom non-illuminated (nightside) areas of the comet and second, the brightness contribution of large gravity-dominated particles in the innermost coma. For our numerical simulations, we used a combination of DSMCgas dynamics simulation and particle propagation by an equation of motion to simulate the dust coma. Oursimulations show that direct activity from the nightside is preferred, contributing≈10% of the total emission.We show that intensity profiles, used to quantify dust outflow behaviour, fit the observations better whennightside activity is present and we suggest that nightside gas emission by CO2or CO is responsible for theobserved dust flux. With the help of a simplified Keplerian modelling approach we exclude large particles ongravitationally bound or ballistic orbits from being the major contributor to the observed dust coma brightness.Additionally, we show the DS:NS ratio as a function of days to perihelion and observe that it is on a similarlevel as in the April OSIRIS time series from February to mid-June 2015, but increases towards a maximum of≥4.07±0.49 shortly after perihelion passage. We suggest that this is correlated to the increasing importanceof H2O production when approaching perihelio

Güneştacının ısıtılma süreçleri ve bu süreçlere dikine ısısal iletkenliğin etkisi

Bu çalısmada, uzun zamandır bilinen günes tacının ısıtılması sorununun üzerinde durulmustur. Gözlemler, zaman içersinde çesitli dalgalanmalar göstermesine karsın Günestacında sürekliliğini koruyan ve 106 108 K düzeyinde sıcaklıklar olduğunu göstermistir. Bilinen odur ki, Günestacı bölgesi optik ince ısınım ve Geçis Bölgesine ısısal iletkenlik yoluyla sürekli olarak erke yitirmektedir. Öte yandan Günestacının sıcaklığı söz konusu düzeylerde sürekliliğini korumaktadır. Günestacının ısıtılması sorununda ısıtmaya aday süreçlerde son yıllarda ön plana çıkan Manyetikses (MS) dalgaları bu çalısmanın konusunu olusturmaktadır. Bu kapsamda öncelikle Günestacının manyetik ve plazma özellikleri incelenmis ve Manyetohidrodinamik bağlamda çözüm arayısına gidilmistir. Çözüm sürecinde MS dalgalarının üretilme süreçlerine değinilmemistir. Çalısmamız boyunca en çok ihtiyacı hissedilenler; iyonlasma sıcaklıkları ve üretildiğini varsaydığımız dalgaların güç tayfının bilinmeyisi olmustur. Sonuç olarak temel Manyetohidrodinamik esitliklerin MS dalgaları için yapılan çözümünün gözlemsel verilerle islenmesi sonucunda MS dalgalarının günestacını ısıtmaya iyi bir aday olduğu belirlenmistir

The effect of thermal conductivity on the outgassing and local gas dynamics from cometary nuclei

Aims. The aim of this work is to investigate the parameters influencing the generation of the inner comae of a comet with a spherical nucleus and to model the gas activity distribution around its nuclei. Here, we investigate the influence of thermal conductivity combined with sub-surface H2O and CO2-ice sources on insolation-driven sublimation and the resulting gas flow field. In the process, we adopted some of the rotational and surface properties of the target of the Rosetta mission, comet 67P/Churyumov-Gerasimenko (67P/CG). Methods. We used a simplified model of heat transport through the surface layer to establish sublimation rates from a H2O- and CO2-ice sub-surface into a vacuum. We then applied the 3D Direct Simulation Monte Carlo method to model the coma as a sublimation-driven flow. The free parameters of the model were used to test the range of effects arising from thermal inertia and the depth of the source on the gas outflow. Results. Thermal inertia and the depth of the sublimation front can have a strong effect on the emission distribution of the flow at the surface. In models with a thermal inertia up to 80 TIU (thermal inertia units: J m−2 K−1 s−1∕2), the H2O distribution can be rotated about the rotation axis by about 20° relative to models with no thermal lag. For CO2, the maximum activity can be shifted towards the sunset terminator with activity going far into the nightside for cases with low thermal diffusivity. The presence of a small amount of CO2 can reduce the presence of H2O by at least an order of magnitude on the nightside by blocking H2O flow. In addition, CO2 can also decrease the speed of the mixed flow in the same region up to 200 m s−1, compared to cases with no CO2 activity. Conclusions. Even low values of the thermal inertia can substantially modify the gas flow field. Including CO2 leads to strong variations in the local CO2/H2O density ratio between the dayside and nightside. CO2 can dominate the gas composition above the nightside and can also act to modify the H2O flow field close to the terminator

Gas terminal velocity from MIRO/Rosetta data using neural network approach

Context. The Microwave Instrument on the Rosetta Orbiter (MIRO) on board the Rosetta spacecraft was designed to investigate the surface and gas activity of the comet 67P/Churyumov-Gerasimenko. The MIRO spectroscopic measurements carry information about the velocity of gas emanating from the nucleus surface. Knowledge of the terminal velocity of the H2O gas is valuable for interpretation of in situ measurements, calibrating 3D coma simulations, and studying the physics of gas acceleration. Aims. Using a neural network technique, we aim to estimate the gas terminal velocity from the entire MIRO dataset of nadir geometry pointings. The velocity of the gas is encoded in the Doppler shift of the measured rotational transitions of o-H$_{2}^{16}$O and o-H$_{2}^{18}$O even when the spectral lines are optically thick with quasi or fully saturated line cores. Methods. Neural networks are robust nonlinear algorithms that can be trained to recognize underlying input to output functional relationships. A training set of about 2200 non-LTE simulated spectra for the two transitions is computed for known input cometary atmospheres, varying column density, temperature, and expansion velocity profiles. Two four-layer networks are used to learn and then predict the gas terminal velocity from the MIRO nadir measured o-H$_{2}^{16}$O and o-H$_{2}^{18}$O spectra lines, respectively. We also quantify the accuracy, stability, and uncertainty of the estimated parameter. Results. Once trained, the neural network is very effective in inverting the measured spectra. We process the entire dataset of MIRO measurements from August 2014 to July 2016, and investigate correlations and temporal evolution of terminal velocities derived from the two spectral lines. The highest terminal velocities obtained from H$_{2}^{18}$O are higher than those from H$_{2}^{16}$O with differences that evolve in time and reach about 150 m s−1 on average around perihelion. A discussion is provided on how to explain this peculiar behavior

El prisma de las seguridades en América Latina. Escenarios regionales y locales

La democracia, los derechos humanos, la violencia y la seguriadd, son temas relacionados, y en buena medida interdependientes, que hoy por hoy constituyen aspectos neurálgicos en la comprensión política, social y económica del orden mundial y, por supuesto, de la realidad latinoamericana. En los últimos años el estudio en temas de la seguridad y su relación con los derechos humanos, consolidación de la democracia y la paz en los países de América Latina, ha tenido grandes avances debido al interés que en los teóricos despierta el análisis de los cambios que empiezan a producirse a mediados de los años setenta tanto en el ámbito global como a escala regional. Entre los cambios internos cabe señalar el fin de las dictaduras militares, las transiciones a la democracia en el marco de las transformaciones en el modelo económico, junto con los retos que la globalización impone. A nivel internacional, el fin de la Guerra Fría trajo consigo el cambio de un esquema bipolar a uno unipolar en lo político, y multipolar en lo económico, de modo que surge un nuevo escenario para la formulación y ejecución de las políticas públicas y, por supuesto, un cambio en el modelo de seguridad, en la medida en que el enemigo comunista desaparece, lo que da lugar a la identificación de otros tipos de amenazas y de manera concomitante al surgimiento de conceptos alternativos de seguridad (humana, ciudadana, multidimensional)

Seguridad en democracia : un reto a la violencia en América Latina

La democracia, los derechos humanos, la violencia y la seguridad, son temas relacionados, y en buena medida interdependientes, que hoy por hoy constituyen aspectos neurálgicos en la compresión política, social y económica del orden mundial y, por supuesto, de la realidad latinoamericana. En los últimos años el estudio en temas de la seguridad y su relación con los derechos humanos, consolidación de la democracia y la paz en los países de América Latina, ha tenido grandes avances debido al interés que en los teóricos despierta el análisis de los cambios que empiezan a producirse a mediados de los años setenta tanto en el ámbito global como a escala regional. Entre los cambios internos cabe señalar el fin de las dictaduras militares, las transiciones a la democracia en el marco de las transformaciones en el modelo económico, junto con los retos que la globalización impone. A nivel internacional, el fin de la Guerra Fría trajo consigo el cambio de un esquema bipolar a uno unipolar en lo político, y multipolar en lo económico, de modo que surge un nuevo escenario para la formulación y ejecución de las políticas públicas y, por supuesto, un cambio en el modelo de seguridad, en la medida en que el enemigo comunista desaparece, lo que da lugar a la identificación de otros tipos de amenazas y de manera concomitante al surgimiento de conceptos alternativos de seguridad (humana, ciudadana, multidimensional).INDICE Presentación 11 Introducción 15 Seguridad pública Doctrinas actores e instituciones; perspectivas juridicas en el tema de seguridad en América Latina Bertha García Gallegos 25 La participación de los ciudadanos en la seguridad pública en México. Algunas reflexiones sobre el impacto limitado y los retos de la participación ciudadana organizada en el campo de la inseguridad José Alfredo Zavaleta Betancourt 43 Seguridad ciudadana: policía para la democracia Nadia Soley Lizarazo Vargas 69 Seguridad global y local: dos visiones en pugna Pablo Emilio Angarita Cañas 89 Los desafíos emergentes a la gestión de la seguridad como consecuencia de la redefinición del espacio público en Argentina Roberto González (coordinador) 113 Seguridad internacional Seguridad democratica, conflicto interno armado y su regionalizacion Alejo Vargas Velásquez 133 Consejo sudamericano de defensa: hacia una integración regional en Defensa Angela Moreira 159 As políticas de segurança continental da oea e a cooperação regional Juliana Santos Maia Bertazzo 175 La intervencion colectiva en Haiti: a propósito de las operaciones de paz César Torres del Río 191 A política de defesa e política externa: coerência ou desencontros? Héctor Luis Saint-Pìerre 203 Las relaciones de seguridad entre Colombia y Ecuador: una nueva construccion de confianza Dolores Bermeo Lara y Nathalie Pabón Ayala 227 Altibajos de la hegemonía militar de Estados Unidos en la cuenca del Caribe: los casos de Colombia, México y Venezuela. (1991-2008) Saúl Mauricio Rodríguez Hernández 253 Seguridad en la región Amazónica Viviana García Pinzón 271 Actores e instituciones Las relaciones civil-militares en la República Argentina Juan Lopez Chorne y Beatriz Irene Wehle 299 Pasado reciente, memoria y ciudadanía en los informes de verdad: el testimonio en el Informe Valech (2004) Graciela Rubio 315 Narcotráfico y militarización en méxico. Territorios, economías regionales y transnacionalismo Salvador Maldonado Aranda 34