35,821 research outputs found

    A process chain for integrating microfluidic interconnection elements by micro- overmoulding of thermoplastic elastomers

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    This paper presents a process chain for in-line integration of microfluidic interconnection elements by a variant of micro-injection moulding (mu IM). A SEBS-based thermoplastic elastomer (TPE) was moulded over polymethylmethacrylate (PMMA) to produce a hybrid microfluidic structure with an aspect ratio of 2. The process chain implemented micro-milling for fabricating micro-structured tool inserts, and mu IM and micro-overmoulding was used for replication. A two-plate mould was used for moulding the substrate, whilst a three-plate mould with a replaceable insert was used for TPE overmoulding. The presented application was an interconnect system for a microfluidic device, which enabled direct fitting of standard tubes into microfluidic substrates. A leakage test showed that the interconnection was leak-proof within a range of flow rates between 0.32 and 0.62 ml min(-1)

    USING THE RANDOM PARAMETERS LOGIT MODEL TO COMBINE REVEALED AND STATED PREFERENCE DATA

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    Recent literature has combined Revealed (RP) and Stated Preference (SP) data in the Multinomial Logit Model (MNL) to estimate the value of environmental goods. However, emerging research has identified that a limitation of the MNL is the assumption of Independently and Identically Distributed (IID) errors, resulting in inaccurate model predictions and inconsistent utility parameters. Our analysis applies an alternative method to combine RP and SP data that takes into account the heterogeneity in both the observable and unobservable components of utility. This allows us to test whether such heterogeneity has an important effect on predicting behavioral choices.Revealed and Stated Preference Data, Scale Factor, Environmental Economics and Policy,

    Microstructure noise, realized volatility, and optimal sampling

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    Recorded prices are known to diverge from their "efficient" values due to the presence of market microstructure contaminations. The microstructure noise creates a dichotomy in the model-free estimation of integrated volatility. While it is theoretically necessary to sum squared returns that are computed over very small intervals to better identify the underlying quadratic variation over a period, the summing of numerous contaminated return data entails substantial accumulation of noise. Using asymptotic arguments as in the extant theoretical literature on the subject, we argue that the realized volatility estimator diverges to infinity almost surely when noise plays a role. While realized volatility cannot be a consistent estimate of the quadratic variation of the log price process, we show that a standardized version of the realized volatility estimator can be employed to uncover the second moment of the (unobserved) noise process. More generally, we show that straightforward sample moments of the noisy return data provide consistent estimates of the moments of the noise process. Finally, we quantify the finite sample bias/variance trade-off that is induced by the accumulation of noisy observations and provide clear and easily implementable directions for optimally sampling contaminated high frequency return data for the purpose of volatility estimationMicrostructure noise, realized volatility

    Relationship between thermodynamics and dynamics of supercooled liquids

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    Diffusivity, a measure for how rapidly a fluid self-mixes, shows an intimate, but seemingly fragmented, connection to thermodynamics. On one hand, the "configurational" contribution to entropy (related to the number of mechanically-stable configurations that fluid molecules can adopt) has long been considered key for predicting supercooled liquid dynamics near the glass transition. On the other hand, the excess entropy (relative to ideal gas) provides a robust scaling for the diffusivity of fluids above the freezing point. Here we provide, to our knowledge, the first evidence that excess entropy also captures how supercooling a fluid modifies its diffusivity, suggesting that dynamics, from ideal gas to glass, is related to a single, standard thermodynamic quantity.Comment: to appear in Journal of Chemical Physic

    THE EFFECT OF RISK AND AUTONOMY ON INDEPENDENT HOG PRODUCERS' CONTRACTING DECISIONS

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    The introduction of vertical coordination in the hog industry has provided producers with new business arrangements for raising hogs. While some researchers have elicited utility functions for hog producers on the basis of income risk, none have addressed autonomy, a factor which appears to be important in business arrangement selection for independent family hog operations. In this study, a method is developed for eliciting a multi-attribute function with attributes of income and autonomy. Utility functions are elicited for a group of Minnesota farrow-to-finish hog producers. For these producers, autonomy dominated risk as the most important attribute in business arrangement selection.Livestock Production/Industries,

    Estimating the Nonmarket Value of Green Technologies Using Partial Data Enrichment Techniques

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    Recent studies have suggested that green technologies may be a cost effective way to manage urban runoff. Literature has also suggests that there needs to be a greater empirical basis to estimate the benefits associated with social values associated with urban trees; we therefore estimate ecosystem benefits of green technologies using emerging data enrichment valuation methods.Environmental Economics and Policy,
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