Road Supply in Central London: Addition of an Ignored Social Cost

Studies examining the social cost of driving usually ignore the opportunity cost of having roads in place: the associated land rents. Especially for geographic regions where land is valuable, including the rent costs may even lead governments to close some roads. By using the London congestion charging zone case, a more general long-run social cost curve is calculated with the addition of the rents. Based on the optimal road usage concept, this study found that including the rents in the cost/benefit analysis significantly affects the results and can increase the social cost by up to 200% and decrease the optimal road usage by 40%

Gravity-Assist Trajectories to the Ice Giants: An Automated Method to Catalog Mass- Or Time-Optimal Solutions

This work presents an automated method of calculating mass (or time) optimal gravity-assist trajectories without a priori knowledge of the flyby-body combination. Since gravity assists are particularly crucial for reaching the outer Solar System, we use the Ice Giants, Uranus and Neptune, as example destinations for this work. Catalogs are also provided that list the most attractive trajectories found over launch dates ranging from 2024 to 2038. The tool developed to implement this method, called the Python EMTG Automated Trade Study Application (PEATSA), iteratively runs the Evolutionary Mission Trajectory Generator (EMTG), a NASA Goddard Space Flight Center in-house trajectory optimization tool. EMTG finds gravity-assist trajectories with impulsive maneuvers using a multiple-shooting structure along with stochastic methods (such as monotonic basin hopping) and may be run with or without an initial guess provided. PEATSA runs instances of EMTG in parallel over a grid of launch dates. After each set of runs completes, the best results within a neighborhood of launch dates are used to seed all other cases in that neighborhood-allowing the solutions across the range of launch dates to improve over each iteration. The results here are compared against trajectories found using a grid-search technique, and PEATSA is found to outperform the grid-search results for most launch years considered

Fundamental constraints on particle tracking with optical tweezers

A general quantum limit to the sensitivity of particle position measurements is derived following the simple principle of the Heisenberg microscope. The value of this limit is calculated for particles in the Rayleigh and Mie scattering regimes, and with parameters which are relevant to optical tweezers experiments. The minimum power required to observe the zero-point motion of a levitating bead is also calculated, with the optimal particle diameter always smaller than the wavelength. We show that recent optical tweezers experiments are within two orders of magnitude of quantum limited sensitivity, suggesting that quantum optical resources may soon play an important role in high sensitivity tracking applications

Expression of ECM proteins fibulin-1 and -2 in acute and chronic liver disease and in cultured rat liver cells

Fibulin-2 has previously been considered as a marker to distinguish rat liver myofibroblasts from hepatic stellate cells. The function of other fibulins in acute or chronic liver damage has not yet been investigated. The aim of this study has been to evaluate the expression of fibulin-1 and -2 in models of rat liver injury and in human liver cirrhosis. Their cellular sources have also been investigated. In normal rat liver, fibulin-1 and -2 were both mainly present in the portal field. Fibulin-1-coding transcripts were detected in total RNA of normal rat liver, whereas fibulin-2 mRNA was only detected by sensitive, real-time quantitative polymerase chain reaction. In acute liver injury, the expression of fibulin-1 was significantly increased (17.23-fold after 48 h), whereas that of fibulin-2 was not modified. The expression of both fibulin-1 and -2 was increased in experimental rat liver cirrhosis (19.16- and 26.47-fold, respectively). At the cellular level, fibulin-1 was detectable in hepatocytes, “activated” hepatic stellate cells, and liver myofibroblasts (2.71-, 122.65-, and 469.48-fold over the expression in normal rat liver), whereas fibulin-2 was restricted to liver myofibroblasts and was regulated by transforming growth factor beta-1 (TGF-β1) in 2-day-old hepatocyte cultures and in liver myofibroblasts. Thus, fibulin-1 and -2 respond differentially to single and repeated damaging noxae, and their expression is differently present in liver cells. Expression of the fibulin-2 gene is regulated by TGF-β1 in liver myofibroblasts

Metabolic capabilities of microorganisms involved in and associated with the anaerobic oxidation of methane

In marine sediments the anaerobic oxidation of methane with sulfate as electron acceptor (AOM) is responsible for the removal of a major part of the greenhouse gas methane. AOM is performed by consortia of anaerobic methane-oxidizing archaea (ANME) and their specific partner bacteria. The physiology of these organisms is poorly understood, which is due to their slow growth with doubling times in the order of months and the phylogenetic diversity in natural and in vitro AOM enrichments. Here we study sediment-free long-term AOM enrichments that were cultivated from seep sediments sampled off the Italian Island Elba (20◦C; hereon called E20) and from hot vents of the Guaymas Basin, Gulf of California, cultivated at 37◦C (G37) or at 50◦C (G50). These enrichments were dominated by consortia of ANME-2 archaea and Seep-SRB2 partner bacteria (E20) or by ANME-1, forming consortia with Seep-SRB2 bacteria (G37) or with bacteria of the HotSeep-1 cluster (G50). We investigate lipid membrane compositions as possible factors for the different temperature affinities of the different ANME clades and show autotrophy as characteristic feature for both ANME clades and their partner bacteria. Although in the absence of additional substrates methane formation was not observed, methanogenesis from methylated substrates (methanol and methylamine) could be quickly stimulated in the E20 and the G37 enrichment. Responsible for methanogenesis are archaea from the genus Methanohalophilus and Methanococcoides, which are minor community members during AOM (1–7h of archaeal 16S rRNA gene amplicons). In the same two cultures also sulfur disproportionation could be quickly stimulated by addition of zero-valent colloidal sulfur. The isolated partner bacteria are likewise minor community members (1–9h of bacterial 16S rRNA gene amplicons), whereas the dominant partner bacteria (Seep-SRB1a, Seep-SRB2, or HotSeep-1) did not grow on elemental sulfur. Our results support a functioning of AOM as syntrophic interaction of obligate methanotrophic archaea that transfer non-molecular reducing equivalents (i.e., via direct interspecies electron transfer) to obligate sulfate-reducing partner bacteria. Additional katabolic processes in these enrichments but also in sulfate methane interfaces are likely performed by minor community members

Subsurface microbial methanotrophic mats in the Black Sea

A nodule-shaped microbial mat was found subsurface in sediments of a gas seep in the anoxic Black Sea. This mat was dominated by ANME-1 archaea and consumed methane and sulfate simultaneously. We propose that such subsurface mats represent the initial stage of previously investigated microbial reefs

Adaptation to transboundary climate risks in trade: investigating actors and strategies for an emerging challenge

There is growing recognition that international trade can transmit climate risks across borders, requiring new forms of and approaches to adaptation. This advanced review synthesizes knowledge on how, by whom and where adaptation actions can be taken in the agriculture and industrial sectors to reduce these transboundary climate risks (TCRs). We find a material difference in the literature on TCRs in agriculture as compared with industrial sectors. Operational and market risks, in particular reductions in food availability, dominate in agriculture, while supply chain and trade-related risks are highlighted for industry. While the origin of the risk (source) is the primary target of adaptation to agricultural TCRs, the general governance structure, such as UNFCCC and WTO deliberations, are important targets in both sectors. Adaptation at the country of destination and along the trade network is of minor importance in both sectors. Regarding the type of adaptation option, agriculture heavily relies on trade policy, agricultural adaptation, and adaptation planning and coordination, while in industry knowledge creation, research and development, and risk management are seen as essential. Governments and the international community are identified as key actors, complemented by businesses and research as critical players in industry. Some measures, such as protectionist trade policies and irrigation, are controversial as they shift risks across countries and sectors, rather than reduce them. While more research is needed, this review shows that a critical mass of evidence on adaptation to TCRs is beginning to emerge, particularly underscoring the importance of international coordination mechanisms. This article is categorized under:. Vulnerability and Adaptation to Climate Change > Institutions for Adaptation Vulnerability and Adaptation to Climate Change > Multilevel and Transnational Climate Change Governance

Sagnac Interferometer Enhanced Particle Tracking in Optical Tweezers

A setup is proposed to enhance tracking of very small particles, by using optical tweezers embedded within a Sagnac interferometer. The achievable signal-to-noise ratio is shown to be enhanced over that for a standard optical tweezers setup. The enhancement factor increases asymptotically as the interferometer visibility approaches 100%, but is capped at a maximum given by the ratio of the trapping field intensity to the detector saturation threshold. For an achievable visibility of 99%, the signal-to-noise ratio is enhanced by a factor of 200, and the minimum trackable particle size is 2.4 times smaller than without the interferometer

Analyzing the Creative Problem-Solving Process: Inventing a Product from a Given Recyclable Item

Detailed documentations of creative invention are scarce in the professional literature, but could be useful to those engaging in or studying the problem solving process. This investigation describes the creative process of graduate students (7 female, 4 male) in a problem-solving theory and practice course grappling with the task of creating products from four identical recyclable items that were circular, star-impressed bottoms of plastic juice bottles. Several popular models of the problem-solving process are compared to the participants’ steps in this invention problem. Participants first provided emotional reactions to the given ill-defined problem of making a product from the specified items. They used several techniques to generate ideas and to restrict or define the problem, choosing an optimal product that fits their require-ments. An analysis of participants’ reflections concerning their creative process showed that although participants first found the problem challenging and could not conceptualize effective products, the idea-generating activities assisted them in making a wide variety of useful products. Participants’ knowledge and skill areas were highlighted by their choices of products. After completing and presenting a first product, participants engaged in additional activities to generate ideas for a second product. The second product was either an improvement of the first product, a new but related product, or a product inspired by the work of others in the class. Products of this loosely defined problem included: maracas, dish, spin top, candy suckers, closet organizers, party decorations, yoyo, ladybug, wall décor, flowers, catch game, party hat, candle holders, moth life cycle, catapult game, toy clock, goblets, castanets, accessory organizer, and spice shaker