Titan's past and future: 3D modeling of a pure nitrogen atmosphere and geological implications

Several clues indicate that Titan's atmosphere has been depleted in methane during some period of its history, possibly as recently as 0.5-1 billion years ago. It could also happen in the future. Under these conditions, the atmosphere becomes only composed of nitrogen with a range of temperature and pressure allowing liquid or solid nitrogen to condense. Here, we explore these exotic climates throughout Titan's history with a 3D Global Climate Model (GCM) including the nitrogen cycle and the radiative effect of nitrogen clouds. We show that for the last billion years, only small polar nitrogen lakes should have formed. Yet, before 1 Ga, a significant part of the atmosphere could have condensed, forming deep nitrogen polar seas, which could have flowed and flooded the equatorial regions. Alternatively, nitrogen could be frozen on the surface like on Triton, but this would require an initial surface albedo higher than 0.65 at 4 Ga. Such a state could be stable even today if nitrogen ice albedo is higher than this value. According to our model, nitrogen flows and rain may have been efficient to erode the surface. Thus, we can speculate that a paleo-nitrogen cycle may explain the erosion and the age of Titan's surface, and may have produced some of the present valley networks and shorelines. Moreover, by diffusion of liquid nitrogen in the crust, a paleo-nitrogen cycle could be responsible of the flattening of the polar regions and be at the origin of the methane outgassing on Titan.Comment: Accepted for publication in Icarus on July 7, 201

The edge of the young Galactic disc

In this work we report and discuss the detection of two distant diffuse stellar groups in the third Galactic quadrant. They are composed of young stars, with spectral types ranging from late O to late B, and lie at galactocentric distances between 15 and 20 kpc. These groups are located in the area of two cataloged open clusters (VdB-Hagen~04 and Ruprecht~30), projected towards the Vela-Puppis constellations, and within the core of the Canis Major over-density. Their reddening and distance has been estimated analyzing their color-color and color-magnitude diagrams, derived from deep $UBV$ photometry. The existence of young star aggregates at such extreme distances from the Galactic center challenges the commonly accepted scenario in which the Galactic disc has a sharp cut-off at about 14 kpc from the Galactic center, and indicates that it extends to much greater distances (as also supported by recent detection of CO molecular complexes well beyond this distance). While the groups we find in the area of Ruprecht~30 are compatible with the Orion and Norma-Cygnus spiral arms, respectively, the distant group we identify in the region of VdB-Hagen~4 lies in the external regions of the Norma-Cygnus arm, at a galactocentric distance ($\sim$20 kpc) where no young stars had been detected so far in the optical.Comment: 45 pages, 11 eps figure, accepted for publication in the Astrophysical Journa

Impact of Clear Air Act Regulations on Nitrogen Fate and Transport in the Neuse River Basin

2012 S.C. Water Resources Conference - Exploring Opportunities for Collaborative Water Research, Policy and Managemen

Tenfold Metalation of Ferrocene: Synthesis, Structures and Metallophilic Interactions in FeC10(HgX)10

The permercuration of ferrocene was achieved by reacting ferrocene with 10 equivalents of mercury(II) butyrate Hg(O2CC3H7)2 in a facile one‐pot reaction in multi‐gram scale and high yields. The butyrate groups in FeC10(HgX)10 (X=O2CC3H7) can be exchanged by treatment with trifluoro‐ or trichloroacetic acid (X=O2CCF3, O2CCCl3). Substitution of the trifluoroacetate groups by halides (X=Cl, F) proceeds easily in aqueous THF. The completeness of metalation was confirmed by NMR and vibrational spectroscopy, mass spectrometry, as well as elemental analysis. Additionally, the first crystal structures of permetallated metallocenes are presented: FeC10(HgX)10 (X=Cl, O2CCF3, O2CCCl3)

Provision of pandemic disease information by health sciences librarians: a multisite comparative case series.

Objective: The research provides an understanding of pandemic information needs and informs professional development initiatives for librarians in disaster medicine. Methods: Utilizing a multisite, comparative case series design, the researchers conducted semi-structured interviews and examined supplementary materials in the form of organizational documents, correspondence, and websites to create a complete picture of each case. The rigor of the case series was ensured through data and investigator triangulation. Interview transcripts were coded using NVivo to identify common themes and points of comparison. Results: Comparison of the four cases revealed a distinct difference between “client-initiated” and “librarian-initiated” provision of pandemic information. Librarian-initiated projects utilized social software to “push” information, whereas client-initiated projects operated within patron-determined parameters to deliver information. Health care administrators were identified as a key audience for pandemic information, and news agencies were utilized as essential information sources. Librarians\u27 skills at evaluating available information proved crucial for selecting best-quality evidence to support administrative decision making. Conclusions: Qualitative analysis resulted in increased understanding of pandemic information needs and identified best practices for disseminating information during periods of high organizational stress caused by an influx of new cases of an unknown infectious disease

Support Networks and Family Empowerment in Early Intervention

Despite the importance of empowerment and the support network of families who receive early intervention (EI) with a family-centered approach, there is little evidence of a relationship between these two variables and family characteristics that might influence this relationship. This study analyzes the correlations between the perception of empowerment of the families, the family supports used, and the socio-demographic factors of both the child and the family. The study consisted of 44 families who received family-centered EI services. Our results show that families mainly used formal supports, followed by informal supports, and, to a lesser extent, intermediate supports. This indicates that families with children who receive EI preferably use the support network based on EI programs, schools, and professionals. Along with this formal support network, primary caregivers rely on their partners, parents, or friends—that is, the informal support network. Family empowerment was not correlated with age, diagnosis, or the reason for referral to EI; on the other hand, it was related to the supports where the families with the lowest empowerment scores were those who made greater use of formal support over informal support. Early intervention professionals must know, from the first encounter, the type and level of support of each family to enhance the development of the child and promote empowerment in families.Educació