Design and trade-offs of a pole-sitter mission

This paper provides a mission analysis and systems design of a pole-sitter mission, i.e. a spacecraft that is continuously above an Earth Pole, and can provide real-time, continuous and hemispherical coverage of the polar regions. Two different propulsion strategies are proposed: solar electric propulsion (SEP) and SEP hybridized with a solar sail. For both, minimum-propellant pole-sitter orbits and transfers are designed, assuming Soyuz and Ariane 5 launch options. A mass budget analysis allows for a tradeoff between mission lifetime and payload mass capacity (up to 7 years for 100 kg), and candidate payloads for a range of applications are investigated

Long-term study of the impact of methotrexate on serum cytokines and lymphocyte subsets in patients with active rheumatoid arthritis: correlation with pharmacokinetic measures

Objective To describe changes in immune parameters observed during long-term methotrexate (MTX) therapy in patients with active rheumatoid arthritis (RA) and explore correlations with simultaneously measured MTX pharmacokinetic (PKC) parameters. Design Prospective, open-label, long-term mechanism of action study. Setting University clinic. Methods MTX was initiated at a single weekly oral dose of 7.5 mg and dose adjusted for efficacy and toxicity for the duration of the study. Standard measures of disease activity were performed at baseline and every 6–36 months. Serum cytokine measurements in blood together with lymphocyte surface immunophenotypes and stimulated peripheral blood mononuclear cell (PBMC) cytokine production were assessed at each clinical evaluation. Results Cytokine concentrations exhibited multiple significant correlations with disease activity measures over time. The strongest correlations observed were for interleukin (IL)-6 (r=0.45, p<0.0001 for swollen joints and r=0.32, p=0.002 for tender joints) and IL-8 (r=0.25, p=0.01 for swollen joints). Significant decreases from baseline were observed in serum IL-1B, IL-6 and IL-8 concentrations. The most significant changes were observed for IL-6 (p<0.001). Significant increases from baseline were observed in IL-2 release from PBMCs ex vivo (p<0.01). In parallel, multiple statistically significant correlations were observed between MTX PKC measures and immune parameters. The change in swollen joint count correlated inversely with the change in area under the curve (AUC) for MTX (r=−0.63, p=0.007). Conclusions MTX therapy of patients with RA is accompanied by a variety of changes in serum cytokine expression, which in turn correlate strongly with clinical disease activity and MTX pharmacokinetics (PKCs). These data strongly support the notion that MTX mediates profound and functionally relevant effects on the immunological hierarchy in the RA lesion

Rapid Assessment of Wetland Ecosystem Services (RAWES): An example from Colombo, Sri Lanka

Wetlands make essential positive contributions to multiple dimensions of human wellbeing. However, recognition of these benefits is often lacking in decision-making, compromising the wellbeing of both the ecosystem and is many linked human beneficiaries. Wetland site managers, decision-makers and stakeholders all need to better understand the benefits provided by wetlands. Despite a plethora of available assessment techniques, very few approaches are genuinely rapid, applicable across different wetland types or consider the realities of time and money resource constraints. The Rapid Assessment of Wetland Ecosystem Services (RAWES) approach is presented as a method that meets these needs, illustrated through its practical application in over 60 different wetland sites supporting development of a Wetland Strategy for the Metro Colombo Region, Sri Lanka. The approach is based on the trained, local assessors using a variety of field indicators in order to assess the positive or negative contribution over 30 wetland ecosystem services provide at local, regional or global scales. Outputs are simplified, signalling to decision-makers the diversity of interlinked ecosystem service outcomes consequent from management policies and actions

Ramsar convention on Wetlands, resolution XIII.17: Rapidly assessing wetland ecosystem services

A Resolution agreed in October 20918 at CoP of the Ramsar Convention on Wetlands - Resolution XIII.17: Rapidly assessing wetland ecosystem services - on a method for the rapid assessment of wetland ecosystem service

Non-Keplerian orbits using low thrust, high ISP propulsion systems

The technology of high ISP propulsion systems with long lifetime and low thrust is improving, and opens up numerous possibilities for future missions. The use of continuous thrust can be applied in all directions including prependicular to the flight direction to force the spacecraft out of a natural orbit (or A orbit) into a displaced orbit (a non-Keplerian or B orbit): such orbits could have a diverse range of potential applications. Using the equations of motion we generate a catalogue of these B orbits corresponding to displaced orbits about the Sun, Mercury, Venus, Earth, the Moon, Mars, Phobos and Deimos, the dwarf planet Ceres, and Saturn. For each system and a given thrust, contours both in and perpendicular to the plane of the ecliptic are produced in the rotating frame, in addition to an equithrust surface. Together these illustrate the possible domain of B orbits for low thrust values between 0 and 300mN. Further, the required thrust vector orientation for the B orbit is obtained and illustrated. The sub-category of solar sail enabled missions is also considered. Such a catalogue of B orbits enables an efficient method of indentifying regions of possible displaced orbits for potential use in future missions

Opportunities and barriers for FinTech in SAARC and ASEAN Countries

This article assesses the opportunities and challenges for different categories of FinTechs in the SAARC and ASEAN regions. We consider the global financial inclusion data released by the World Bank and map the responses to gain insights into the opportunities and challenges for FinTechs in the respective regions. We develop a new index, termed the FinTech Opportunity Index (FOI), to conceptualise the opportunities and barriers based on individual savings, borrowings, purchasing behaviour, and payment preferences. We note that FinTech services have potential opportunities for expansion in the ASEAN regions but less so in the SAARC regions. The need for different types of FinTech services varies between regions. Services such as crowdfunding, neobanks, and InsurTech have potential in the ASEAN regions, especially with the positive attitude towards entrepreneurship and asset investments. In the SAARC regions, InsurTechs linked to health care has potential along with LendTechs and neobanks. We further note that males, and the young are more likely adopters of FinTechs in both regions. The analysis suggests the need for innovative promotions and education to motivate the more sceptical, especially women and the elderly population, to adopt FinTech services

Autonomous path planning for on-orbit servicing vehicles

On-orbit servicing has long been considered as a means of reducing mission costs. While automated on-orbit servicing of satellites in LEO and GEO has yet to be realised, the International Space Station (ISS) will require servicing in a number of forms for re-supply, external visual inspection and maintenance. This paper will discuss a unified approach to path planning for such servicing vehicles using artificial potential field methods. In particular, path-constrained rendezvous and docking of the ESA Automated Transfer Vehicle (ATV) at the ISS will be investigated as will mission and path planning tools for the Daimler-Chrysler Aerospace ISS Inspector free-flying camera. Future applications for free-flying microcameras and co-operative control between multiple free-flyers for on-orbit assembly will also be considered

Initial Conditions for Bubble Universes

The "bubble universes" of Coleman and De Luccia play a crucial role in string cosmology. Since our own Universe is supposed to be of this kind, bubble cosmology should supply definite answers to the long-standing questions regarding cosmological initial conditions. In particular, it must explain how an initial singularity is avoided, and also how the initial conditions for Inflation were established. We argue that the simplest non-anthropic approach to these problems involves a requirement that the spatial sections defined by distinguished bubble observers should not be allowed to have arbitrarily small volumes. Casimir energy is a popular candidate for a quantum effect which can ensure this, but [because it violates energy conditions] there is a danger that it could lead to non-perturbative instabilities in string theory. We make a simple proposal for the initial conditions of a bubble universe, and show that our proposal ensures that the system is non-perturbatively stable. Thus, low-entropy conditions can be established at the beginning of a bubble universe without violating the Second Law of thermodynamics and without leading to instability in string theory. These conditions are inherited from the ambient spacetime.Comment: Further clarifications; 28 pages including three eps files. This is the final [accepted for publication] versio