5,302 research outputs found
Machine Understanding of Human Behavior
A widely accepted prediction is that computing will move to the background, weaving itself into the fabric of our everyday living spaces and projecting the human user into the foreground. If this prediction is to come true, then next generation computing, which we will call human computing, should be about anticipatory user interfaces that should be human-centered, built for humans based on human models. They should transcend the traditional keyboard and mouse to include natural, human-like interactive functions including understanding and emulating certain human behaviors such as affective and social signaling. This article discusses a number of components of human behavior, how they might be integrated into computers, and how far we are from realizing the front end of human computing, that is, how far are we from enabling computers to understand human behavior
Aqueous Humor Outflow Structure and Function Imaging At the Bench and Bedside: A Review.
Anterior segment glaucoma clinical care and research has recently gained new focus because of novel imaging modalities and the advent of angle-based surgical treatments. Traditional investigation drawn to the trabecular meshwork now emphasizes the entire conventional aqueous humor outflow (AHO) pathway from the anterior chamber to the episcleral vein. AHO investigation can be divided into structural and functional assessments using different methods. The historical basis for studying the anterior segment of the eye and AHO in glaucoma is discussed. Structural studies of AHO are reviewed and include traditional pathological approaches to modern tools such as multi-model two-photon microscopy and optical coherence tomography. Functional assessment focuses on visualizing AHO itself through a variety of non-real-time and real-time techniques such as aqueous angiography. Implications of distal outflow resistance and segmental AHO are discussed with an emphasis on melding bench-side research to viable clinical applications. Through the development of an improved structure: function relationship for AHO in the anterior segment of the normal and diseased eye, a better understanding of the eye with improved therapeutics may be developed
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From M-ary Query to Bit Query: a new strategy for efficient large-scale RFID identification
The tag collision avoidance has been viewed as one of the most important research problems in RFID communications and bit tracking technology has been widely embedded in query tree (QT) based algorithms to tackle such challenge. Existing solutions show further opportunity to greatly improve the reading performance because collision queries and empty queries are not fully explored. In this paper, a bit query (BQ) strategy based Mary query tree protocol (BQMT) is presented, which can not only eliminate idle queries but also separate collided tags into many small subsets and make full use of the collided bits. To further optimize the reading performance, a modified dual prefixes matching (MDPM) mechanism is presented to allow multiple tags to respond in the same slot and thus significantly reduce the number of queries. Theoretical analysis and simulations are supplemented to validate the effectiveness of the proposed BQMT and MDPM, which outperform the existing QT-based algorithms. Also, the BQMT and MDPM can be combined to BQMDPM to improve the reading performance in system efficiency, total identification time, communication complexity and average energy cost
Modeling and Optimizing High Pressure Liquid Chromatography (HPLC) Columns for the Separation of Biopharmaceuticals
One of the most critical steps in the production of pharmaceuticals is the separation of the desired compound from reaction byproducts and environmental contaminants. Among the most sensitive of these methods is High Pressure Liquid Chromatography (HPLC), in which an initial mixture of compounds is forced by high pressure fluid flow through a column packed with a porous solid medium. Size and charge interactions with the solid phase cause the compounds to elute at different times from the column.
The performance of an HPLC column is highly dependent on properties such as the length, ambient temperature, inlet pressure, and solid medium porosity. The ideal parameters are conventionally determined by purchasing and physically testing a series of columns, which can be prohibitive in cost, time, and materials. Thus there currently exists a pressing need for computer models to simulate the separation of two or more compounds in order to expedite the onerous process of physical optimization.
This study sought to simulate the physical phenomena that underlie the elution process in an HPLC column, and optimize the conditions such that species separation and purity are maximized. The computing software COMSOL was used to model the involved physics, which comprised the flow of a mobile phase through a porous matrix, modeled by the Navier-Stokes Brinkman equation; the diffusion and dispersion of two solutes in the matrix, modeled by the general mass transfer equation; and the effect of external heating on the materials’ behavior, modeled by the general heat equation. The geometry of the HPLC column consisted of an axisymmetric two-dimensional tube filled with a uniformly distributed porous matrix.
This model column was evaluated by simulating the separation of creatine and creatinine, two closely-related molecules involved in muscle tissue energetics. Once the model was tailored to a high degree of accuracy in comparison with experimental data, the column and species parameters were optimized. The optimal geometry for the separation of creatine and creatinine by HPLC, was a column of diameter 1.05 mm and length 78.4 mm, with a packed bed of spherical particles 5 µm in diameter. The optimal column temperature for this particular situation was found to be lower, at 15℃, as this slightly increases peak resolution but also elution time.
Though concentration plots derived from this model corroborated experimental elution absorbance plots with relatively high fidelity, lingering issues remain, including the unexpectedly small influence of temperature on elution characteristics. Future models may seek to correct this calculation error by including a less steep concentration gradient at the inlet at initial time points. Additionally, variations in column heating were found to have a very small effect on the diffusion of the solute bands, so the external temperature was excluded from the optimization process. The successful implementation of this model indicates that HPLC chromatography can be feasibly represented by computer modeling, and more specific models can reduce the time and material costs of extensive physical testing
Replica-molded electro-optic polymer Mach–Zehnder modulator
A Mach-Zehnder electro-optic polymer amplitude modulator is fabricated by a simple and high-throughput soft-stamp replica-molding technique. The modulator structure incorporates the highly nonlinear and stable chromophore, AJL8, doped in amorphous polycarbonate. Single-arm phase-retardation results in a halfwave voltage (V-pi) of 8.4 V at 1600 nm. The on/off extinction ratio is better than 19 dB, resulting from precise Y-branch power splitters and good waveguide uniformity. These results indicate that the simple fabrication process allows for good optical performance from high-fidelity replicas of the original master devices
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