2,777 research outputs found

    Assessment of Real Estate Brokerage Service Quality with a Practicing Professional's Instrument

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    This study explores factors that affect service quality for a large residential real estate brokerage in a diverse midwestern city. It examines the extent to which overall service quality influences homebuyers to recommend the brokerage firm and to use the firm for future transactions. A Linear Structural Relations model is fit to data using the firm's service quality instrument. Results indicate statistically significant relationships between both agent characteristics and the tangible aspects of the firm, and three measures of overall service quality. Implications for the real estate industry are discussed and suggestions for improvement and future research are provided.

    On the Fredholm property of bisingular pseudodifferential operators

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    For operators belonging either to a class of global bisingular pseudodifferential operators on Rm×RnR^m \times R^n or to a class of bisingular pseudodifferential operators on a product M×NM \times N of two closed smooth manifolds, we show the equivalence of their ellipticity (defined by the invertibility of certain associated homogeneous principal symbols) and their Fredholm mapping property in associated scales of Sobolev spaces. We also prove the spectral invariance of these operator classes and then extend these results to the even larger classes of Toeplitz type operators.Comment: 21 pages. Expanded sections 3 and 4. Corrected typos. Added reference

    Correlating the nanostructure of Al-oxide with deposition conditions and dielectric contributions of two-level systems in perspective of superconducting quantum circuits

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    This work is concerned with Al/Al-oxide(AlOx_{x})/Al-layer systems which are important for Josephson-junction-based superconducting devices such as quantum bits. The device performance is limited by noise, which has been to a large degree assigned to the presence and properties of two-level tunneling systems in the amorphous AlOx_{x} tunnel barrier. The study is focused on the correlation of the fabrication conditions, nanostructural and nanochemical properties and the occurrence of two-level tunneling systems with particular emphasis on the AlOx_{x}-layer. Electron-beam evaporation with two different processes and sputter deposition were used for structure fabrication, and the effect of illumination by ultraviolet light during Al-oxide formation is elucidated. Characterization was performed by analytical transmission electron microscopy and low-temperature dielectric measurements. We show that the fabrication conditions have a strong impact on the nanostructural and nanochemical properties of the layer systems and the properties of two-level tunneling systems. Based on the understanding of the observed structural characteristics, routes are derived towards the fabrication of Al/AlOx_{x}/Al-layers systems with improved properties.Comment: 28 pages, 4 figure

    Orion Entry Flight Control Stability and Performance

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    The Orion Spacecraft will be required to perform entry and landing functions for both Low Earth Orbit (LEO) and Lunar return missions, utilizing only the Command Module (CM) with its unique systems and GN&C design. This paper presents the current CM Flight Control System (FCS) design to support entry and landing, with a focus on analyses that have supported its development to date. The CM FCS will have to provide for spacecraft stability and control while following guidance or manual commands during exo-atmospheric flight, after Service Module separation, translational powered flight required of the CM, atmospheric flight supporting both direct entry and skip trajectories down to drogue chute deploy, and during roll attitude reorientation just prior to touchdown. Various studies and analyses have been performed or are on-going supporting an overall FCS design with reasonably sized Reaction Control System (RCS) jets, that minimizes fuel usage, that provides appropriate command following but with reasonable stability and control margin. Results from these efforts to date are included, with particular attention on design issues that have emerged, such as the struggle to accommodate sub-sonic pitch and yaw control without using excessively large jets that could have a detrimental impact on vehicle weight. Apollo, with a similar shape, struggled with this issue as well. Outstanding CM FCS related design and analysis issues, planned for future effort, are also briefly be discussed

    Trees on K-12 School Campuses in Virginia

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    Trees and saplings growing on K-12 school campuses were investigated in 105 school districts across Virginia. There were 2812 trees (\u3e12.5 cm stem diameter at 1.4 m above ground level) inventoried across all campuses. The mean and median campus tree population was 27 and 18, respectively. Loblolly pine (Pinus taeda L.) was the most abundant species, accounting for 11% of all inventoried trees. Red maple (Acer rubrum L.) was the most frequently inventoried species, present on 44% of the campuses. Sapling (trees with 2.5-12.5 cm stem diameter at 1.4 m above ground level) populations were similar to tree populations. The mean and median campus sapling population was 23 and 13, respectively. Flowering dogwood (Cornus florida L.) and red maple were the most abundant sapling species, each accounting for about 10% of all inventoried saplings. Flowering dogwood, red maple, Bradford pear (Pyrus calleryana Decne. ‘Bradford’), willow oak (Quercus phellos L. ), and ornamental cherry (Prunus spp. ) were the most frequently inventoried sapling species, each present on more than 25% of the campuses. Across all campuses, species diversity was relatively low: less than 10 species accounted for over 50% of the inventoried trees and saplings. Prominent Virginia natives, in particular Carya and Quercus species, were under represented in the inventory

    Droplets on Soft Surfaces Exhibit a Reluctance to Coalesce due to an Intervening Wetting Ridge

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    Microscale interactions with deformable substrates are of fundamental interest for studying self-assembly processes and the mobility of cells on soft surfaces, with applications in traction force microscopy. The behavior of microscale water droplets on a soft polymer substrate is investigated. Droplets formed by condensation on the soft substrate are reluctant to coalesce, which leads to coverage of the surface with clusters of droplets assembled in a honeycomb-like pattern. Cryogenically fixed in this state, scanning electron microscopy of these droplets reveals the presence of an intervening wetting ridge of the polymer that acts as a barrier between neighboring droplets and prevents coalescence. A linear elastic deformation model is developed to predict this surface profile and corroborate the observed behavior

    Free Floating Microcultures of Human Fetal Ventral Mesencephalon

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    Direct Evidence of the Discontinuous Character of the Kosterlitz-Thouless Jump

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    It is numerically shown that the discontinuous character of the helicity modulus of the two-dimensional XY model at the Kosterlitz-Thouless (KT) transition can be directly related to a higher order derivative of the free energy without presuming any {\it a priori} knowledge of the nature of the transition. It is also suggested that this higher order derivative is of intrinsic interest in that it gives an additional characteristics of the KT transition which might be associated with a universal number akin to the universal value of the helicity modulus at the critical temperature.Comment: 4 pages, to appear in PR

    Rectal Bleeding Associated With Chronic Pancreatitis

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    Pseudocyst formation, with its attendant complications of compression, rupture, bleeding and fistula formation, is a well known complication of chronic pancreatitis. In 1966 Berne and Edmondson drew attention to the often fatal outcome of pancreatico-colonic fistula complicated by hemorrhage. We present two cases of this rare complication of chronic pancreatitis as defined by the Marseille classification

    Involution and Constrained Dynamics I: The Dirac Approach

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    We study the theory of systems with constraints from the point of view of the formal theory of partial differential equations. For finite-dimensional systems we show that the Dirac algorithm completes the equations of motion to an involutive system. We discuss the implications of this identification for field theories and argue that the involution analysis is more general and flexible than the Dirac approach. We also derive intrinsic expressions for the number of degrees of freedom.Comment: 28 pages, latex, no figure
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