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There is growing scholarly attention towards understanding the role of environmental factors on entrepreneurial action, decision-making, and outcomes. The external enabler (EE) framework provides a unified and comprehensive understanding of how different types of macro- environmental changes, ranging from technological, natural-environmental to socio-demographic changes, impact the substance, rate, and quantity of entrepreneurship. Scholarly interest in applying the EE framework to uncover the presence of heterogeneity in entrepreneurial action based on spatial, sectoral, temporal, and demographic dimensions is emerging. By focusing on opacity, which is a core construct of the EE framework, and using a Knowledge Problem approach to underscore temporal dimension of EEs, this study develops a time-calibrated understanding of opacity related to the external enablement of entrepreneurial action. Given the focus on the evolving nature of an EE, we conduct our empirical investigation in the gradually advancing Artificial Intelligence industry by drawing data from Crunchbase. [ABSTRACT FROM AUTHOR]

In four years, the Medicine Hat Teacher Supervision and Evaluation Project has evolved from centrally planned innovation into an integral part of the district's internal organization, enabling teachers and administrators to pursue educational change and professional development and receive recognition in a climate of rising expectations, trust, and collaboration. (SV)

Ecosystem-based fisheries management requires a fundamental understanding of ecosystem boundaries and interspecies interactions. We report a delineation of fish and invertebrate data collected by trawl survey along the Maine, USA, coast. Principal components analysis (PCA) reduced the multidimensionality of the data and created new variables from correlations among species. Bootstrapped PCA was employed to assess PCA structure using eigenvalue variation and species associations using eigenvector variation. A general linear model related structure of fish community identified in PCA to depth, temperature, longitude, and interactions among these variables. Generally, alongshore and onshore--offshore assemblage patterns related to oceanographic gradients, with seasonal variation. PCA-created variables act as indicators of biodiversity and are related to the scale of observation, allowing for multiple scales to be integrated if data are available. Species targeted and gear used along with spatial extent and sampling density must be considered when management zonation is to be undertaken but would allow boundaries to follow biological and physical gradients rather than relying on the typical political and economic variables, avoiding ecologically deleterious spatial patterns in fishing pressure or other instances of de facto zoning. Regardless, this study describes some contributing factors causing division of species assemblages that should be considered. Resume: La gestion des peches basee sur les ecosystemes necessite une comprehension fondamentale des frontieres entre les ecosystemes et des interactions entre les especes. Nous presentons une delimitation des donnees sur les poissons et les invertebres recoltees par inventaire au chalut le long de la cote du Maine, E.-U. Une analyse des composantes principales (PCA) a reduit la nature multidimensionnelle des donnees et a cree de nouvelles variables a partir des correlations entre les especes. Une PCA avec bootstrap a servi a estimer la structure de la PCA, ainsi que les associations d'especes, d'apres la variation des valeurs propres. Un modele lineaire general a relie la structure de la communaute de poissons identifiee dans la PCA a la profondeur, a la temperature, a la longitude et aux interactions entre ces variables. En general, les patrons de regroupements le long de la cote et entre la cote et le large sont associes a des gradients oceaniques avec une variation saisonniere. Les variables creees par la PCA servent d'indicateurs de la biodiversite et sont reliees a l'echelle d'observation, ce qui permet l'integration de plusieurs echelles lorsque les donnees sont suffisantes. Il est necessaire de tenir compte des especes ciblees et des engins de peche utilises, de meme que de l'etendue spatiale et de la densite d'echantillonnage, afin d'entreprendre un zonage de gestion; celui-ci doit permettre aux frontieres de suivre les gradients biologiques et physiques plutot que de se baser sur les variables politiques et economiques habituelles; ainsi, il est possible d'eviter les effets spatiaux nefastes de la pression de peche et des autres circonstances du zonage de facto. Neanmoins, notre etude decrit certains facteurs a considerer qui contribuent a la division des regroupements d'especes. [Traduit par la Redaction], Introduction Biodiversity is a structural characteristic describing ecosystems that provides information on the state (Slocombe 1998) as well as the adaptive capacity and robustness of the ecosystem to external impacts [...]

Family firms can enjoy substantial Iongevity. Ironically, however, they are often imperiled by the very process that is essential to this Iongevity. Using the concept of managerial discretion as a [...]

A new combined lutetium oxyorthosilicate (LSO) PET/CT scanner with an extended axial field-of-view (FOV) of 21.8 cm has been developed (Biograph TruePoint PET/CT with TrueV; Siemens Molecular Imaging) and introduced into clinical practice. The scanner includes the recently announced point spread function (PSF) reconstruction algorithm. The PET components incorporate four rings of 48 detector blocks, 5.4 cm x 5.4 cm in cross-section. Each block comprises a 13 x 13 matrix of 4 x 4 x 20 [mm.sup.3] elements. Data are acquired with a 4.5 ns coincidence time window and an energy window of 425-650 keV. The physical performance of the new scanner has been evaluated according to the recently revised National Electrical Manufacturers Association (NEMA) NU 2-2007 standard and the results have been compared with a previous PET/CT design that incorporates three rings of block detectors with an axial coverage of 16.2 cm (Biograph TruePoint PET/CT; Siemens Molecular Imaging). In addition to the phantom measurements, patient Noise Equivalent Count Rates (NECRs) have been estimated for a range of patients with different body weights (42-154 kg). The average spatial resolution is the same for both scanners: 4.4 mm (FWHM) and 5.0 mm (FWHM) at 1 cm and 10 cm respectively from the center of the transverse FOV. The scatter fractions of the Biograph TruePoint and Biograph TruePoint TrueV are comparable at 32%. Compared to the three ring design, the system sensitivity and peak NECR with smoothed randoms correction (1R) increase by 82% and 73%, respectively. The increase in sensitivity from the extended axial coverage of the Biograph TruePoint PET/CT with TrueV should allow a decrease in either scan time or injected dose without compromising diagnostic image quality. The contrast improvement with the PSF reconstruction potentially offers enhanced detectability for small lesions. Index Terms--Extended FOV, NEMA measurements, PET/CT, PSF reconstruction.

Social entrepreneurship (SE) is emerging as a common approach to meeting social needs. However, SE founders appear to be organizing under both for-profit and nonprofit organizational forms to engage in [...]

The use of x-ray computed tomography (CT)-based attenuation correction for positron emission tomography (PET) in PET/CT systems requires the transformation of CT Hounsfieid units (HU) to linear attenuation coefficients at 511 keV (LA[C.sub.511]). This cannot be done perfectly from a single peak kilovolt (kVp) CT scan due to variability in Compton and photoelectric composition and, thus, an approximate transformation must be employed. One difficulty in this lies in accurately determining the linear attenuation coefficients (LAC) in actual human tissue. Typically, phantoms consisting of synthetic materials thought to be approximate human tissue equivalents are employed instead. A potentially more accurate approach would be to use dual kVp CT scans to estimate LA[C.sub.511] in actual human tissue and then base the single kVp transformation on these data. This approach would also permit an assessment of the dispersion of actual tissue values about the two-component trend lines typically used for the single kVp transformation. In this paper, we develop and assess this methodology. Index Terms--Attenuation correction, human tissue, linear attenuation coefficient, PET, PET/CT.

We propose a new methodology for analyzing clinical positron emission tomography (PET) count rate performance that involves matching net trues (prompts--delayeds) and randoms (delayeds) count rate responses measured on a reference phantom to the actual patient data. We employ these estimated response curves to compute a performance metric closely related to the noise equivalent count rate, as a function of the total singles event rate in the system. From this we can determine the peak performance value relative to the measured performance for any individual acquisition. This maximum performance value depends only on the emitter and attenuator distributions. These peak count rates can be used to derive frame durations for equivalent noise, and correlated with patient weight. We can also determine the singles rate and, thereby, activity necessary to achieve this maximum performance and, based on the known activity in the patient, predict optimal injected doses. Index Terms--Clinical performance, count rate, injected dose, NEC, patient weight, PNECR, positron emission tomography (PET).