2,671 research outputs found

    Reforming the Contested Convention: Rethinking the Presidential Nomination Process

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    The presidential nomination process could be substantially improved through a few minor tweaks that would reduce unnecessary uncertainty, bolster its democratic underpinnings, and improve the connections among its various components. First, certain fundamental rules governing national conventions should be determined well in advance of the presidential nominating process, before any primaries or caucuses are held or delegates selected, and not be subject to change or suspension at the convention itself. Second, parties should enhance the democratic moorings of their national conventions by requiring presidential candidates to win a greater number of presidential preference votes to be placed into nomination. Third, state parties should tie the various components of the presidential nomination process more closely together by adopting a blend of the Democratic and Republican Parties’ current approaches. When a candidate is allotted national convention delegates based on the results of a presidential preference vote, the candidate should have a voice in selecting those delegates, and those delegates in turn should be bound to vote for that candidate, at least during the first round of voting at the national convention

    Water, High-Altitude Condensates, and Possible Methane Depletion in the Atmosphere of the Warm Super-Neptune WASP-107b

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    The super-Neptune exoplanet WASP-107b is an exciting target for atmosphere characterization. It has an unusually large atmospheric scale height and a small, bright host star, raising the possibility of precise constraints on its current nature and formation history. We report the first atmospheric study of WASP-107b, a Hubble Space Telescope measurement of its near-infrared transmission spectrum. We determined the planet's composition with two techniques: atmospheric retrieval based on the transmission spectrum and interior structure modeling based on the observed mass and radius. The interior structure models set a 3σ3\,\sigma upper limit on the atmospheric metallicity of 30×30\times solar. The transmission spectrum shows strong evidence for water absorption (6.5σ6.5\,\sigma confidence), and the retrieved water abundance is consistent with expectations for a solar abundance pattern. The inferred carbon-to-oxygen ratio is subsolar at 2.7σ2.7\,\sigma confidence, which we attribute to possible methane depletion in the atmosphere. The spectral features are smaller than predicted for a cloud-free composition, crossing less than one scale height. A thick condensate layer at high altitudes (0.1 - 3 mbar) is needed to match the observations. We find that physically motivated cloud models with moderate sedimentation efficiency (fsed=0.3f_\mathrm{sed} = 0.3) or hazes with a particle size of 0.3 μ\mum reproduce the observed spectral feature amplitude. Taken together, these findings serve as an illustration of the diversity and complexity of exoplanet atmospheres. The community can look forward to more such results with the high precision and wide spectral coverage afforded by future observing facilities.Comment: 10 pages, 4 figures; accepted to ApJ

    The application of ‘just in time’ to reverse logistics: a feasibility study from the UK multiple retail sector

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    Purpose: The purpose of the research is to assess the operational feasibility of applying just in time (JIT) practices to a UK multiple retailers’ reverse logistics (RL) function for waste packaging materials, whilst also assessing possible benefits which may be derived from such an application. Research Approach: The research adopts an embedded case study approach, which included multiple analyses at different nodes of the retail and distribution operational units within the organisation. Interviews were undertaken which allowed for the creation of a narrative outlining the organisation’s operating environments and RL function dynamics, this was then compared to key JIT success factors. Findings: At the functional level there are a number of attributes within the case organisation which would positively influence the adoption of JIT processes, given their relationship with critical success factors outlined within the literature. It is also observed that where negative relationships do exist, they are mainly attitudinal in nature and thus through process reengineering and appropriate training could be averted. On balance the findings indicate that with minimal restructuring and investment the case organisation would be capable of supporting JIT processes. Possible implications of a successful JIT implementation are also discussed. These suggest that although duplicate movement within the network may occur, there would also be efficiency increases in both forward and reverse operations allowing for significant savings. Practical Impact: A new process model is proposed for the case organisations forward and reverse operations which incorporates JITP elements into the RL function. This creates a new just in time reverse logistics (JITRL) environment where collection activities are removed from forward operations, resulting in possible cost savings for the overall distribution network derived from increased efficiencies and capital expenditure. Originality: The research presented provides a unique and novel approach to the application of JIT systems, not only showing that it is possible in operational contexts, but also that JITRL systems may offer significant benefits beyond this organisation, to distribution networks in operations within a similar environment to that of the case organisation

    Resolved Spectroscopy of the T8.5 and Y0-0.5 Binary WISEPC J121756.91+162640.2AB

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    We present 0.9 - 2.5 um resolved spectra for the ultracool binary WISEPC J121756.91+162640.2AB. The system consists of a pair of brown dwarfs that straddles the currently defined T/Y spectral type boundary. We use synthetic spectra generated by model atmospheres that include chloride and sulfide clouds (Morley et al.), the distance to the system (Dupuy & Kraus), and the radius of each component based on evolutionary models (Saumon & Marley) to determine a probable range of physical properties for the binary. The effective temperature of the T8.5 primary is 550 - 600 K, and that of the Y0 - Y0.5 secondary is 450 K. The atmospheres of both components are either free of clouds or have extremely thin cloud layers. We find that the masses of the primary and secondary are 30 and 22 M_Jup, respectively, and that the age of the system is 4 - 8 Gyr. This age is consistent with astrometric measurements (Dupuy & Kraus) that show that the system has kinematics intermediate between those of the thin and thick disks of the Galaxy. An older age is also consistent with an indication by the H - K colors that the system is slightly metal-poor.Comment: 21 pages which include 6 Figures and 3 Tables. Accepted on November 8 2013 for publication in Ap

    Ignorance is bliss: General and robust cancellation of decoherence via no-knowledge quantum feedback

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    A "no-knowledge" measurement of an open quantum system yields no information about any system observable; it only returns noise input from the environment. Surprisingly, performing such a no-knowledge measurement can be advantageous. We prove that a system undergoing no-knowledge monitoring has reversible noise, which can be cancelled by directly feeding back the measurement signal. We show how no-knowledge feedback control can be used to cancel decoherence in an arbitrary quantum system coupled to a Markovian reservoir that is being monitored. Since no-knowledge feedback does not depend on the system state or Hamiltonian, such decoherence cancellation is guaranteed to be general, robust and can operate in conjunction with any other quantum control protocol. As an application, we show that no-knowledge feedback could be used to improve the performance of dissipative quantum computers subjected to local loss.Comment: 6 pages + 2 pages supplemental material, 3 figure

    Cross-cultural comparison of genetic and cultural transmission of smoking initiation using an extended twin kinship model

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    Background: Considerable evidence from twin and adoption studies indicates that genetic and shared environmental factors play a role in the initiation of smoking behavior. Although twin and adoption designs are powerful to detect genetic and environmental influences, they do not provide information on the processes of assortative mating and parent–offspring transmission and their contribution to the variability explained by genetic and/or environmental factors. Methods: We examined the role of genetic and environmental factors in individual differences for smoking initiation (SI) using an extended kinship design. This design allows the simultaneous testing of additive and non-additive genetic, shared and individual-specific environmental factors, as well as sex differences in the expression of genes and environment in the presence of assortative mating and combined genetic and cultural transmission, while also estimating the regression of the prevalence of SI on age. A dichotomous lifetime ‘ever’ smoking measure was obtained from twins and relatives in the ‘Virginia 30,000’ sample and the ‘Australian 25,000’. Results: Results demonstrate that both genetic and environmental factors play a significant role in the liability to SI. Major influences on individual differences appeared to be additive genetic and unique environmental effects, with smaller contributions from assortative mating, shared sibling environment, twin environment, cultural transmission, and resulting genotype-environment covariance. Age regression of the prevalence of SI was significant. The finding of negative cultural transmission without dominance led us to investigate more closely two possible mechanisms for the lower parent–offspring correlations compared to the sibling and DZ twin correlations in subsets of the data: (1) age × gene interaction, and (2) social homogamy. Neither of the mechanism provided a significantly better explanation of the data. Conclusions: This study showed significant heritability, partly due to assortment, and significant effects of primarily non-parental shared environment on liability to SI

    Thermal reaction norms and the scale of temperature variation: latitudinal vulnerability of intertidal Nacellid limpets to climate change

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    The thermal reaction norms of 4 closely related intertidal Nacellid limpets, Antarctic (Nacella concinna), New Zealand (Cellana ornata), Australia (C. tramoserica) and Singapore (C. radiata), were compared across environments with different temperature magnitude, variability and predictability, to test their relative vulnerability to different scales of climate warming. Lethal limits were measured alongside a newly developed metric of “duration tenacity”, which was tested at different temperatures to calculate the thermal reaction norm of limpet adductor muscle fatigue. Except in C. tramoserica which had a wide optimum range with two break points, duration tenacity did not follow a typical aerobic capacity curve but was best described by a single break point at an optimum temperature. Thermal reaction norms were shifted to warmer temperatures in warmer environments; the optimum temperature for tenacity (Topt) increased from 1.0°C (N. concinna) to 14.3°C (C. ornata) to 18.0°C (an average for the optimum range of C. tramoserica) to 27.6°C (C. radiata). The temperature limits for duration tenacity of the 4 species were most consistently correlated with both maximum sea surface temperature and summer maximum in situ habitat logger temperature. Tropical C. radiata, which lives in the least variable and most predictable environment, generally had the lowest warming tolerance and thermal safety margin (WT and TSM; respectively the thermal buffer of CTmax and Topt over habitat temperature). However, the two temperate species, C. ornata and C. tramoserica, which live in a variable and seasonally unpredictable microhabitat, had the lowest TSM relative to in situ logger temperature. N. concinna which lives in the most variable, but seasonally predictable microhabitat, generally had the highest TSMs. Intertidal animals live at the highly variable interface between terrestrial and marine biomes and even small changes in the magnitude and predictability of their environment could markedly influence their future distributions
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