Non-solar noble gas abundances in the atmosphere of Jupiter

The thermodynamic stability of clathrate hydrate is calculated to predict the formation conditions corresponding to a range of solar system parameters. The calculations were performed using the statistical mechanical theory developed by van der Waals and Platteeuw (1959) and existing experimental data concerning clathrate hydrate and its components. Dissociation pressures and partition functions (Langmuir constants) are predicted at low pressure for CO clathrate (hydrate) using the properties of chemicals similar to CO. It is argued that nonsolar but well constrained noble gas abundances may be measurable by the Galileo spacecraft in the Jovian atmosphere if the observed carbon enhancement is due to bombardment of the atmosphere by clathrate-bearing planetesimals sometime after planetary formation. The noble gas abundances of the Jovian satellite Titan are predicted, assuming that most of the methane in Titan is accreted as clathrate. It is suggested that under thermodynamically appropriate conditions, complete clathration of water ice could have occurred in high-pressure nebulas around giant planets, but probably not in the outer solar nebula. The stability of clathrate in other pressure ranges is also discussed

Counterterrorism Strategies

Since the attacks of 11 September, a kind of conventional wisdom about counterterrorism has emerged. On one hand, the “new terrorism” involves the violent expression of a radical religious agenda, suicide attackers, and mass- casualty violence. It is, therefore, both harder to deter and more destructive than the old ideological and ethno- nationalist varieties of terrorism, whose practitioners, in Brian Michael Jenkins’s now classic (and obsolete) formulation, wanted a lot of people watching, not a lot of people dead. On the other hand, the takedown, led by the United States, of the Taliban regime in Afghanistan forced the operational core of al-Qa‘ida to disperse and the transnational terror- ism network to become even more flat and decentralized

The U.S. Navy

Although Africa has long been a low strategic priority for the United States, Washington now has a sharp and pronounced strategic interest in protecting access to rich reserves of sub-Saharan oil and gas, mainly in the vicinity of the Gulf of Guinea, as part of its drive to reduce dependence on Middle East suppliers. By 2010, Africa’s share of U.S. oil imports could rise to 20 percent, and China has begun to engage the United States in a geopolitical contest for hydro- carbons and other economic and political benefits in sub-Saharan Africa

Somalia and the Pirates. ESF Working Paper No. 33, 18 December 2009

Piracy is defined by The Hague Centre for Strategic Studies as an "act of boarding or attempting to board any ship with the apparent intent to commit theft or any other crime and with the apparent intent or capability to use force in furtherance of that act." And it is estimated that from 1995 to 2009, around 730 persons were killed or are presumed dead, approximately 3,850 seafarers were held hostage, around 230 were kidnapped and ransomed, nearly 800 were seriously injured and hundreds more were threatened with guns and knives. (See paper by Rob de Wijk). In November 2009, CEPS held a European Security Forum seminar, in collaboration with the Institute for Strategic Studies, the Centre for the Democratic Control of Armed Forces and the Geneva Centre for Security Policy, to focus on the issue of Somalia and the Pirates, chaired by Francois Heisbourg. Four eminent specialists in this field: David Anderson, Rob de Wijk, Steven Haines and Jonathon Stevenson looked at the links with Somalia, and the historical, legal, political and security dimensions of the troubling success of piracy in today’s world. Their conclusions and recommendations for future action are brought together in this ESF 33 Working Paper

Perspectives of healthcare providers on the nutritional management of patients on haemodialysis in Australia: An interview study

Objective To describe the perspectives of healthcare providers on the nutritional management of patients on haemodialysis, which may inform strategies for improving patient-centred nutritional care. Design Face-to-face semistructured interviews were conducted until data saturation, and thematic analysis based on principles of grounded theory. Setting 21 haemodialysis centres across Australia. Participants 42 haemodialysis clinicians (nephrologists and nephrology trainees (15), nurses (12) and dietitians (15)) were purposively sampled to obtain a range of demographic characteristics and clinical experiences. Results Six themes were identified: responding to changing clinical status (individualising strategies to patient needs, prioritising acute events, adapting guidelines), integrating patient circumstances (assimilating life priorities, access and affordability), delineating specialty roles in collaborative structures (shared and cohesive care, pivotal role of dietary expertise, facilitating access to nutritional care, perpetuating conflicting advice and patient confusion, devaluing nutritional specialty), empowerment for behaviour change (enabling comprehension of complexities, building autonomy and ownership, developing self-efficacy through engagement, tailoring self-management strategies), initiating and sustaining motivation (encountering motivational hurdles, empathy for confronting life changes, fostering non-judgemental relationships, emphasising symptomatic and tangible benefits, harnessing support networks), and organisational and staffing barriers (staffing shortfalls, readdressing system inefficiencies). Conclusions Organisational support with collaborative multidisciplinary teams and individualised patient care were seen as necessary for developing positive patient-clinician relationships, delivering consistent nutrition advice, and building and sustaining patient motivation to enable change in dietary behaviour. Improving service delivery and developing and delivering targeted, multifaceted self-management interventions may enhance current nutritional management of patients on haemodialysis

Thermodynamics of clathrate hydrate at low and high pressures with application to the outer solar system

The thermodynamic stability of clathrate hydrate is calculated under a wide range of temperature and pressure conditions applicable to solar system problems, using a statistical mechanical theory developed by van der Waals and Platteeuw (1959) and existing experimental data on properties of clathrate hydrates and their components. At low pressure, dissociation pressures and partition functions (Langmuir constants) for CO clathrate (hydrate) have been predicted, using the properties of clathrate containing, as guests, molecules similar to CO. The comparable or higher propensity of CO to incorporate in clathrate relative to N_2 is used to argue for high CO-to-N_2 ratios in primordial Titan if N_2 was accreted as clathrate. The relative incorporation of noble gases in clathrate from a solar composition gas at low temperatures is calculated and applied to the case of giant-planet atmospheres and icy satellites. It is argued that nonsolar but well-constrained noble gas abundances will be measured by Galileo in the Jovian atmosphere if the observed carbon enhancement is due to bombardment of the atmosphere by clathrate-bearing planetesimals sometime after planetary formation. The noble gas abundances in Titan's atmosphere are also predicted under the hypothesis that much of the satellite's methane accreted as clathrate. Double occupancy of clathrate cages by H_2 and CH_4 in contact with a solar composition gas is examined, and it is concluded that potentially important amounts of H_2 may have incorporated in satellites as clathrate. The kinetics of clathrate formation is also examined, and it is suggested that, under thermodynamically appropriate conditions, essentially complete clathration of water ice could have occurred in high-pressure nebulae around giant planets but probably not in the outer solar nebula; comets probably did not aggregate as clathrate. At moderate pressures, the phase diagram for methane clathrate hydrate in the presence of 15% ammonia (relative to water) is constructed, and application to the early Titan atmospheric composition is described. The high-pressure stability of CH_4, N_2, and mixed CH_4-N_2 clathrate hydrate is calculated; conversion back to water and CH_4 and/ or N_2 fluids or solids is predicted for pressures ≳ 12 kilobars (independent of temperature) and temperatures ≳ 320 K (independent of pressure). The effect of ammonia is to shrink the T-P stability field of clathrate with increasing ammonia concentration. These results imply that (1) clathrate is stable throughout the interior of Oberon- and Rhea-sized icy satellites, and (2) clathrate incorporated in the innermost icy regions of Titan would have decomposed, perhaps allowing buoyant methane to rise. Brief speculation on the implications of this conclusion for the origin of surficial methane on Titan is given. A list of suggested experiments and observations to test the theory and its predictions is presented

New Analysis Indicates No Thermal Inversion in the Atmosphere of HD 209458b

An important focus of exoplanet research is the determination of the atmospheric temperature structure of strongly irradiated gas giant planets, or hot Jupiters. HD 209458b is the prototypical exoplanet for atmospheric thermal inversions, but this assertion does not take into account recently obtained data or newer data reduction techniques. We re-examine this claim by investigating all publicly available Spitzer Space Telescope secondary-eclipse photometric data of HD 209458b and performing a self-consistent analysis. We employ data reduction techniques that minimize stellar centroid variations, apply sophisticated models to known Spitzer systematics, and account for time-correlated noise in the data. We derive new secondary-eclipse depths of 0.119 +/- 0.007%, 0.123 +/- 0.006%, 0.134 +/- 0.035%, and 0.215 +/- 0.008% in the 3.6, 4.5, 5.8, and 8.0 micron bandpasses, respectively. We feed these results into a Bayesian atmospheric retrieval analysis and determine that it is unnecessary to invoke a thermal inversion to explain our secondary-eclipse depths. The data are well-fitted by a temperature model that decreases monotonically between pressure levels of 1 and 0.01 bars. We conclude that there is no evidence for a thermal inversion in the atmosphere of HD 209458b.Comment: 8 pages, 5 figures; accepted for publication in Ap

Dialect in digitally mediated written interaction: a survey of the geohistorical distribution of the ditransitive in British English using Twitter

Recent research (Gerwin, 2013; Siewierska & Hollmann, 2007; Yáñez Bouza & Denison, 2015) uses historical and contemporary corpora to quantify diachronic and spatial distributions of variants of the ditransitive in British English. Each study pays particular attention to ditransitives with two pronominal objects, where internal factors influencing variation are reduced primarily to the choice of pronoun and verb type. Three variants are attested, a ‘prepositional dative’ (PDAT - ‘send it to me’), a double-object (GTD - ‘send me it’) and an alternative regionally marked double object construction (TGD - ‘send it me’). Corpus evidence reveals the pronominal TGD as the most frequent variant until the beginning of the 19th century, when the PDAT gained preference. The pronominal GTD, now considered canonical, emerges at the beginning of the 20th century. Broad agreement over the geographical distribution of the ditransitive is based primarily on maps drawn from the Survey of English Dialects (SED), but “comprehensive frequency data” (Yáñez Bouza & Denison, 2015, p.248) is lacking. The current project provides detailed frequency data drawn from language use on Twitter which is accurately mapped according to GPS coding. This map shows remarkable crossover with the SED maps, demonstrating both the stability of the geographical distribution over time and the amenability of “interactive written discourse” (Ferrara, Brunner, & Whittemore, 1991) to the expression of dialect. The results detail a large degree of variation in the relative frequency of each variable over physical space. Such variation brings into focus some important questions regarding the nature of a language as conceived in formal linguistic theory and a problematic tendency to ‘lump together’ large, linguistically diverse regions and treat them as one entity (Siewierska & Hollmann, 2007, p.97). Instead, using statistical tests for difference, the present study groups contiguous regions by the relative probabilistic frequencies of each variant. The results have implications for dialect geography, dialect syntax and recent approaches concerning regionally sensitive probabilistic approaches to grammar (Bresnan & Ford, 2010)