2,479 research outputs found

    Aviation, Herbert Hoover and His “American Plan”

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    Mountain Lion (Puma concolor) Population Characteristics and Resource Selection in the North Dakota Badlands

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    Mountain lions (Puma concolor) have significant ecological impacts on the ecosystems they inhabit, leading to both biological and social ramifications. Yet, due to the relatively recent natural recolonization by mountain lions of the Little Missouri Badlands Region of western North Dakota, detailed data regarding many aspects of this population have been lacking. Therefore, we studied mountain lions occupying the Badlands Region to improve our understanding of mountain lion population ecology, resource selection, and occurrence in North Dakota. Our objectives were to: 1) improve the accuracy of home range size, subadult movement, and survival estimates of mountain lions in North Dakota, 2) employ statistical population reconstruction (SPR) techniques to model the mountain lion population in North Dakota and use it to estimate population abundance, population density, and investigate population trajectory, 3) investigate individual and population-level resource selection and develop a population-level resource selection function (RSF) for mountain lions across the Badlands, and 4) create a statewide habitat suitability map for the species and compare it with previous models, and 5) estimate statewide carrying capacity for mountain lions based upon quantity of suitable habitat. During 2015 and 2016, we captured and marked nine mountain lions (3 M, 6 F) across the Badlands. We included data collected from 16 other mountain lions marked during previous research in our analyses when appropriate. Annual 95% home ranges for males averaged 295.44 km2 (CI = 226.64–364.25 km2) while females averaged 127.49 km2 (CI = 83.27–171.71 km2). We recorded subadult movement patterns for one subadult male and one subadult female. Between 2012 and 2016, average annual survival was estimated at 45.6% (95% CI = 26.4–66.1). Sex-specific survival was estimated at 58.9% (95% CI = 33.8–80.0) for females and 25.9% (95% CI = 8.9–55.5) for males. Additionally, we recorded 17 cause-specific mortalities of marked mountain lions over the same five-year period. Between 2005 and 2017, annual population abundance estimates ranged from low a of 27 total mountain lions (95% CI = 1–52) in 2005-06 to a high of 165 total mountain lions (95% CI = 89–241) in 2011-12. We produced 12 annual density estimates (2005-17), which ranged from a low of 0.45 total mountain lions/100 km2 in 2005-06 to a high of 2.8 total mountain lions/100 km2 in 2011-12. Mountain lions exhibited varying individual responses to habitat components, yet population-level patterns emerged. Mountain lions showed strong positive selection for landscape ruggedness, edge habitat, and forest, while displaying negative responses to disturbed anthropogenic landcovers. We used the population-level RSF to map suitable habitat for mountain lions across the state of North Dakota, which indicated 3,969 km2 of suitable habitat in North Dakota, approximately 60% of which occurred in the Badlands and Missouri River Breaks regions. Our model validated well, and produced a carrying capacity estimate of 38 to 61 (range = 11–88) resident adult mountain lions, based upon published population densities and quantity of suitable habitat in North Dakota. Managers in North Dakota now have the information needed to make scientificallyinformed decisions regarding the current and future management of this apex predator

    Listing Specialization and Residential Real Estate Licensee

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    Earlier research has found that specialization by real estate agents creates economies of scope for real estate firms. So far, however, no research has addressed this issue at the agent level. The question this research seeks to answer is whether specialization in one side of the real estate transaction increases agent income. The most important finding is that specialization has an asymmetric impact on earnings. Specializing in listings positively enhances agent income. In contrast, specialization on the selling side has an adverse affect on agent income. The implications of these findings for the consumer and real estate industry are also examined.

    The Capitalization of Seller Paid Consessions

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    Using a hedonic pricing model, we analyze the capitalization of total seller paid discount points and closing costs into the price of a house. We hypothesize that sellers are concerned about the sales price net of total seller paid concessions (SPNC), rather than the exact terms of the transaction. Since the SPNC is easily ascertained in the negotiation process, we further hypothesize that total seller paid concessions (TSPC) are fully capitalized into the sales price. To test this hypothesis, sales price is regressed on a set of control variables including TSPC. In this framework, TSPC will be positive and not significantly different from one if concessions are fully capitalized. The empirical results provide support for the capitalization hypothesis. Negotiation strategies and study limitations follow from the empirical results.

    Endogenous and Ectopic Expression ofnogginSuggests a Conserved Mechanism for Regulation of BMP Function during Limb and Somite Patterning

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    AbstractThe genenoggin,originally cloned inXenopus,encodes a secreted factor expressed in the Spemann organizer, where it functions to oppose the ventralizing influence of bone morphogenetic proteins (BMPs). Noggin protein acts by binding directly to BMPs, thereby preventing them from interacting with their receptors. Here we describe the pattern of expression of the chickennoggingene during somite and limb development, two tissues in which BMPs have been postulated to play essential patterning roles. We find thatnogginis expressed in dynamic restricted patterns consistent with an important role in the modulation of BMP signaling. Using a replication competent retrovirus we have ectopically expressednogginin developing somitic and limb bud mesoderm and observed phenotypes consistent with complete block of BMP activity. This includes suppression of lateral somite differentiation and, in the limb, complete inhibition of chondrogenesis and local suppression of programmed cell death. In addition, we find that ectopicnogginexpression in the limb has no effect on anteroposterior limb pattern, suggesting that BMPs are unlikely to play a significant role in this process. Taken together, our results indicate thatnogginis a key regulator of vertebrate limb and somite patterning and suggest that the antagonistic Noggin–BMP interaction is a widely used mechanism to modulate BMP signaling during multiple inductive events in vertebrate embryogenesis

    The rank filtration and Robinson’s complex

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    AbstractFor a functor from the category of finite sets to abelian groups, Robinson constructed a bicomplex in [A. Robinson, Gamma homology, Lie representations and E∞ multiplications, Invent. Math. 152 (2) (2003) 331–348] which computes the stable derived invariants of the functor as defined by Dold–Puppe in [A. Dold, D. Puppe, Homologie nicht-additiver Funktoren. Anwendungen., Ann. Inst. Fourier (Grenoble) 11 (1961) 201–312]. We identify a subcomplex of Robinson’s bicomplex which is analogous to a normalization and also computes these invariants. We show that this new bicomplex arises from a natural filtration of the functor obtained by taking left Kan approximations on subcategories of bounded cardinality
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