An estimate of the chemical composition of Titan's lakes

Hundreds of radar-dark patches interpreted as lakes have been discovered in the north and south polar regions of Titan. We have estimated the composition of these lakes by using the direct abundance measurements from the Gas Chromatograph Mass Spectrometer (GCMS) aboard the Huygens probe and recent photochemical models based on the vertical temperature profile derived by the Huygens Atmospheric Structure Instrument (HASI). Thermodynamic equilibrium is assumed between the atmosphere and the lakes, which are also considered as nonideal solutions. We find that the main constituents of the lakes are ethane (C2H6) (~76-79%), propane (C3H8) (~7-8%), methane (CH4) (~5-10%), hydrogen cyanide (HCN) (~2-3%), butene (C4H8) (~1%), butane (C4H10) (~1%) and acetylene (C2H2) (~1%). The calculated composition of lakes is then substantially different from what has been expected from models elaborated prior to the exploration of Titan by the Cassini-Huygens spacecraft.Comment: 5 pages, 2 figures, accepted in ApJ

Photochemical enrichment of deuterium in Titan's atmosphere: new insights from Cassini-Huygens

Cassini-Huygens data are used to re-examine the potential sources of the D/H enhancement over solar, measured in methane, in Titan's atmosphere. Assuming that the system is closed with respect to carbon, the use of constraints from the Huygens probe for the determination of the current mass of atmospheric methane and the most up-to-date determination of D/H from Cassini/CIRS infrared spectra allow us to show that photochemical enrichment of deuterium is not sufficient to be the sole mechanism yielding the measured D/H value. A possible fractionation between CH3D and CH4 during the escape process may slightly enhance the deuterium enrichment, but is not sufficient to explain the observed D/H value over the range of escape values proposed in the literature. Hence, alternative mechanisms such as a primordial deuterium enrichment must be combined with the photochemical enrichment in Titan's atmosphere in order to explain its current D/H value.Comment: 4 pages, 3 figures, accepted in ApJ

Preserving the environment

Altres títols : Naturally creativ

PENGARUH KUANTITAS LAYANAN DAN KEPERCAYAAN TERHADAP KEPUASAN NASABAH KREDIT MIKRO PADA BANK PT. BTPN ARGAMAKMUR

The purpose of this research were the impact of service quality toward :ustomer satisfaction at BTPN Bank of Argamalcnur Branch, 2J Analyze the impact of irust toward customer satisfaction at BTPN Bank of Argamakmur Branch, 3) Analyze rhe impact of service quality and trust toward customer satisfaction at BTPN Bank of Argamakmur Branch, 4) Identified the variable that had dominance impact toward customer satisfaction at BTPN Bank of Argamakmur Branch. Purpose sampling method ',vas used on this research. The numbers of sampling were 155 respondents. Multiple regression analysis was used as research method on this study. The result of study can be summaries: 1) There was significant impact of service quality toward customer satisfaction at BTPN Bank of Argamakmur Branch with the value of coefficient was 0,467; 2J There was significant impact of tn-rst toward customer satisfaction at BTPN Bank of Argamakmur Branch with the value of coefficient was 0,382,3) There was significant impact of service quality and trust toward customer satisfaction at BTPN Bank of Argamalnnur Branch with the value of inpact was 67 ,2o/o and 32,8o/a of the rest was influence by other factors, 4) Based on the study found that the service quality had more strong impact to customer satisfaction rather than of trust at BTPN Bank of Argamakmur Branch

Interactions between landscape changes and host communities can regulate echinococcus multilocularis transmission

An area close to the Qinghai-Tibet plateau region and subject to intensive deforestation contains a large focus of human alveolar echinococcosis while sporadic human cases occur in the Doubs region of eastern France. The current review analyses and compares epidemiological and ecological results obtained in both regions. Analysis of rodent species assemblages within quantified rural landscapes in central China and eastern France shows a significant association between host species for the pathogenic helminth Echinococcus multilocularis, with prevalences of human alveolar echinococcosis and with land area under shrubland or grassland. This suggests that at the regional scale landscape can affect human disease distribution through interaction with small mammal communities and their population dynamics. Lidicker's ROMPA hypothesis helps to explain this association and provides a novel explanation of how landscape changes may result in increased risk of a rodent-borne zoonotic disease

Negative ions formed in N₂/CH₄/Ar discharge – a simulation of Titan's atmosphere chemistry

The formation of negative ions produced in a negative point-to-plane corona discharge fed by a Ar/N2//CH4/ gas mixture has been studied using mass spectrometry. The measurements were carried out in flowing regime at ambient temperature and a reduced pressure of 460 mbar. The CN ? anion has been found to be the most dominant negative ion in the discharge and is believed to be the precursor of heavier negative ions such as C3/N ? and C5/N ? . The most likely pathway for the formation of such molecular anions is H-loss dissociative electron attachment to HCN, H3/CN and H5/CN formed in the discharge. These same anions have been detected in Titan's atmosphere and the present experiments may provide some novel insights into the chemical and physical mechanisms prevalent in Titan's atmosphere and hence assist in the interpretation of results from the Cassini Huygens space mission

Electron-attachment rates for carbon-rich molecules in protoplanetary atmospheres: the role of chemical differences

The formation of anionic species in the interstellar medium from interaction of linear molecules containing carbon, nitrogen and hydrogen as atomic components (polyynes) with free electrons in the environment is modelled via a quantum treatment of the collision dynamics. The ensuing integral cross sections are employed to obtain the corresponding attachment rates over a broad range of temperatures for the electrons. The calculations unequivocally show that a parametrization form often employed for such rates yields a broad range of values that turn out to be specific for each molecular species considered, thus excluding using a unique set for the whole class of polyynes.Comment: accepted to be published on MNRA