10,733 research outputs found

    Innovation, Managerial Effort, and Start-Up Performance

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    Managers of start-up firms make a number of important yet understudied decisions, such as whether or not to develop a new product, whether or not to choose a high-technology product or service, whether or not to use external assistance, and the amount of time and effort they will devote to their new company. These choices are informed by their access to various resources, such as the size of the management team, its education level, its previous experience working at start-ups, and other attributes. In this paper we consider how these resources influence optimal provision of effort, and examine decisions about innovative behavior (i.e., to market a novel or high-technology product) and managerial exertion (i.e., the hours per week spent by the managers and their decision to supplement their own efforts by employing external assistance such as consulting services)

    Computing the local pressure in molecular dynamics simulations

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    Computer simulations of inhomogeneous soft matter systems often require accurate methods for computing the local pressure. We present a simple derivation, based on the virial relation, of two equivalent expressions for the local (atomistic) pressure in a molecular dynamics simulation. One of these expressions, previously derived by other authors via a different route, involves summation over interactions between particles within the region of interest; the other involves summation over interactions across the boundary of the region of interest. We illustrate our derivation using simulations of a simple osmotic system; both expressions produce accurate results even when the region of interest over which the pressure is measured is very small.Comment: 11 pages, 4 figure

    Bird Dispersal Techniques

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    Conflicts between humans and birds likely have existed since agricultural practices began. Paintings from ancient Greek, Egyptian, and Roman civilizations depict birds attacking crops. In Great Britain, recording of efforts at reducing bird damage began in the 1400s, with books on bird control written in the 1600s. Even so, the problem persists. Avian damage to crops remains an issue today, but we also are concerned with damage to homes, businesses, and aircraft, and the possibility of disease transmission from birds to humans or livestock. Successful dispersal techniques should capitalize on bird sensory capabilities. If birds cannot perceive the dispersal technique, it will not be effective in dispersing birds. Not only must birds be able to perceive a dispersal technique, they also must interpret the technique as a threat to their safety. A technique that worked initially may fail later as birds habituate to it and no longer perceive the technique as threatening. For some species, the introduction of limited lethal control reinforces non-lethal dispersal techniques, as the birds again perceive the non-lethal technique as potentially dangerous. For other species, changing techniques is necessary, because they may not react to the death of a flock member and therefore still not interpret the scare technique as a threat. In either case, changing techniques and using multiple techniques in an integrated manner are essential for deterring birds from sensitive areas. No single technique or tool will deter birds in every instance or situation; there is no silver bullet. Successful bird dispersal involves a combination of tools and timing of use, as well as the skill and persistence of biologists and wildlife control operators (WCOs). The following sections offer overviews of various techniques that have been used to mitigate bird problems in various situations, as well as examples that highlight successful bird dispersal programs

    SweetSpot: Near-Infrared Observations of Thirteen Type Ia Supernovae from a New NOAO Survey Probing the Nearby Smooth Hubble Flow

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    We present 13 Type Ia supernovae (SNe Ia) observed in the restframe near-infrared (NIR) from 0.02 < z < 0.09 with the WIYN High-resolution Infrared Camera (WHIRC) on the WIYN 3.5-m telescope. With only 1-3 points per light curve and a prior on the time of maximum from the spectrum used to type the object we measure an H-band dispersion of spectroscopically normal SNe Ia of 0.164 mag. These observations continue to demonstrate the improved standard brightness of SNe Ia in H-band even with limited data. Our sample includes two SNe Ia at z ~ 0.09, which represent the most distant restframe NIR H-band observations published to date. This modest sample of 13 NIR SNe Ia represent the pilot sample for "SweetSpot" - a three-year NOAO Survey program that will observe 144 SNe Ia in the smooth Hubble flow. By the end of the survey we will have measured the relative distance to a redshift of z ~ 0.05 to 1%. Nearby Type Ia supernova (SN Ia) observations such as these will test the standard nature of SNe Ia in the restframe NIR, allow insight into the nature of dust, and provide a critical anchor for future cosmological SN Ia surveys at higher redshift.Comment: 36 pages, 8 figures, Submitted to Ap

    Bird Dispersal Techniques

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    Conflicts between humans and birds likely have existed since agricultural practices began. Paintings from ancient Greek, Egyptian, and Roman civilizations depict birds attacking crops. In Great Britain, recording of efforts at reducing bird damage began in the 1400s, with books on bird control written in the 1600s. Even so, the problem persists. Avian damage to crops remains an issue today, but we also are concerned with damage to homes, businesses, and aircraft, and the possibility of disease transmission from birds to humans or livestock. Successful dispersal techniques should capitalize on bird sensory capabilities. If birds cannot perceive the dispersal technique, it will not be effective in dispersing birds. Not only must birds be able to perceive a dispersal technique, they also must interpret the technique as a threat to their safety. A technique that worked initially may fail later as birds habituate to it and no longer perceive the technique as threatening. For some species, the introduction of limited lethal control reinforces non-lethal dispersal techniques, as the birds again perceive the non-lethal technique as potentially dangerous. For other species, changing techniques is necessary, because they may not react to the death of a flock member and therefore still not interpret the scare technique as a threat. In either case, changing techniques and using multiple techniques in an integrated manner are essential for deterring birds from sensitive areas. No single technique or tool will deter birds in every instance or situation; there is no silver bullet. Successful bird dispersal involves a combination of tools and timing of use, as well as the skill and persistence of biologists and wildlife control operators (WCOs). The following sections offer overviews of various techniques that have been used to mitigate bird problems in various situations, as well as examples that highlight successful bird dispersal programs

    Strategic Directions in Supermarket Deli/Prepared Foods

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    A.E. Res. 90-1

    A novel method for transient detection in high-cadence optical surveys: Its application for a systematic search for novae in M31

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    [abridged] In large-scale time-domain surveys, the processing of data, from procurement up to the detection of sources, is generally automated. One of the main challenges is contamination by artifacts, especially in regions of strong unresolved emission. We present a novel method for identifying candidates for variables and transients from the outputs of such surveys' data pipelines. We use the method to systematically search for novae in iPTF observations of the bulge of M31. We demonstrate that most artifacts produced by the iPTF pipeline form a locally uniform background of false detections approximately obeying Poissonian statistics, whereas genuine variables and transients as well as artifacts associated with bright stars result in clusters of detections, whose spread is determined by the source localization accuracy. This makes the problem analogous to source detection on images produced by X-ray telescopes, enabling one to utilize tools developed in X-ray astronomy. In particular, we use a wavelet-based source detection algorithm from the Chandra data analysis package CIAO. Starting from ~2.5x10^5 raw detections made by the iPTF data pipeline, we obtain ~4000 unique source candidates. Cross-matching these candidates with the source-catalog of a deep reference image, we find counterparts for ~90% of them. These are either artifacts due to imperfect PSF matching or genuine variable sources. The remaining ~400 detections are transient sources. We identify novae among these candidates by applying selection cuts based on the expected properties of nova lightcurves. Thus, we recovered all 12 known novae registered during the time span of the survey and discovered three nova candidates. Our method is generic and can be applied for mining any target out of the artifacts in optical time-domain data. As it is fully automated, its incompleteness can be accurately computed and corrected for.Comment: 16 pages, 8 figures, accepted to A&
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