423 research outputs found

    Review of the African genera Arantia StÄl and Goetia Karsch (Orthoptera. Tettigoniidae: Phaneropterinae).

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    The genus Arantia is reviewed, the distribution and distinguishing characters given. The three species of Goetia are assigned as subgenus to Arantia. Arantia gestri Griffini is transferred to this new subgenus and synonymized with G. dimidiata BolĂ­var. Other species synonymized are: A. accrana Karsch with A. rectifolia Brunner von Wattenwyl; A. gabunensis Brunner von Wattenwyl with A. regina Karsch; A. mammisignum Karsch and A. tigrina BolĂ­var with A. excelsior Karsch; A. ugandana Rehn is synonymized with A. fasciata (Walker). 6 species from Tropical Africa are newly described: A. (Arantia) quinquemaculata n. sp., A. (Arantia) ivoriana n. sp., A. (Euarantia) tanzanica n. sp., A. (Euarantia) tibiaspinosa n. sp., A. (Euarantia) bispinosa n. sp. and A. (Euarantia) griffinii n. sp. A key to the subgenera and species of Arantia is provided. The tribe Arantiini is synonymized with Holochlorini

    Location, location, location, the impact of registered sex offenders on home sale prices: A case study of McLean County, Illinois

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    Borrowing from the broken windows theory, this paper addresses the impact of sex offenders’ residences on neighborhood’s property values in McLean County, Illinois. Three data sets were combined to explore the relationship: the addresses of registered sex offenders (RSOs) in McLean County, Illinois, the location and property characteristics of homes sold in McLean County between December 2012 to December 2013, and variables from the 2010 U.S. Census. ArcGIS was utilized to create buffers up to 0.2 of a mile around a sold home to measure the concentration of RSOs and sexual predators (SPs) and to calculate the distance from the nearest RSO and SP. The results indicate that as RSO and SP concentration increased, home selling prices decreased by 6,586foreachRSOand6,586 for each RSO and 9,098 for each SP within the buffer. In regards of distance, RSOs and SPs negatively impacted home selling prices the closer they were to a home sale transaction. These findings inform the debate surrounding the requirements placed on sexual offender registration, community notification, and residency restrictions

    The Financial Impact of Registered Sex Offenders on Home Sale Prices: A Case Study of McLean County, Illinois

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    This study extends the current sex offender and housing literature by examining whether the presence of registered sex offenders (RSOs) and sexual predators (SPs) influenced home sale values in a mixed rural/agricultural and urban community. Using ArcGIS, the residences of RSOs in McLean County, Illinois, and home sale transactions, along with property and neighborhood characteristics were geocoded. The associations of home sale values to the distance to the nearest RSO and SP, as well as, the concentrations of RSOs and SPs were examined. Results revealed that each foot increase between the sold home to the residence of the nearest RSO and SP was associated with an increase in home sale prices of 17.03 and 15.25 U.S. dollars, and the concentrations of two or more RSOs and SPs was associated with a reduction in home sale prices of 12,750 and 17,797 U.S. dollars. These findings inform the debate surrounding the requirements placed on sexual offender registration, community notification, and residency restrictions

    Optimum structure for a uniform load over multiple spans

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    This paper presents a new half-plane Michell structure that transmits a uniformly distributed load of infinite horizontal extent to a series of equally-spaced pinned supports. Full kinematic description of the structure is obtained for the case when the maximum allowable tensile stress is greater than or equal to the allowable compressive stress. Although formal proof of optimality of the solution presented is not yet available, the proposed analytical solution is supported by substantial numerical evidence, involving the solution of problems with in excess of 10 billion potential members. Furthermore, numerical solutions for various combinations of unequal allowable stresses suggest the existence of a family of related, simple, and practically relevant structures, which range in form from a Hemp-type arch with vertical hangers to a structure which strongly resembles a cable-stayed bridge

    The impact of insect herbivory on biogeochemical cycling in broadleaved forests varies with temperature

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    Herbivorous insects alter biogeochemical cycling within forests, but the magnitude of these impacts, their global variation, and drivers of this variation remain poorly understood. To address this knowledge gap and help improve biogeochemical models, we established a global network of 74 plots within 40 mature, undisturbed broadleaved forests. We analyzed freshly senesced and green leaves for carbon, nitrogen, phosphorus and silica concentrations, foliar production and herbivory, and stand-level nutrient fluxes. We show more nutrient release by insect herbivores at non-outbreak levels in tropical forests than temperate and boreal forests, that these fluxes increase strongly with mean annual temperature, and that they exceed atmospheric deposition inputs in some localities. Thus, background levels of insect herbivory are sufficiently large to both alter ecosystem element cycling and influence terrestrial carbon cycling. Further, climate can affect interactions between natural populations of plants and herbivores with important consequences for global biogeochemical cycles across broadleaved forests

    Predicting tree distributions in an East African biodiversity hotspot : model selection, data bias and envelope uncertainty

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    The Eastern Arc Mountains (EAMs) of Tanzania and Kenya support some of the most ancient tropical rainforest on Earth. The forests are a global priority for biodiversity conservation and provide vital resources to the Tanzanian population. Here, we make a first attempt to predict the spatial distribution of 40 EAM tree species, using generalised additive models, plot data and environmental predictor maps at sub 1 km resolution. The results of three modelling experiments are presented, investigating predictions obtained by (1) two different procedures for the stepwise selection of predictors, (2) down-weighting absence data, and (3) incorporating an autocovariate term to describe fine-scale spatial aggregation. In response to recent concerns regarding the extrapolation of model predictions beyond the restricted environmental range of training data, we also demonstrate a novel graphical tool for quantifying envelope uncertainty in restricted range niche-based models (envelope uncertainty maps). We find that even for species with very few documented occurrences useful estimates of distribution can be achieved. Initiating selection with a null model is found to be useful for explanatory purposes, while beginning with a full predictor set can over-fit the data. We show that a simple multimodel average of these two best-model predictions yields a superior compromise between generality and precision (parsimony). Down-weighting absences shifts the balance of errors in favour of higher sensitivity, reducing the number of serious mistakes (i.e., falsely predicted absences); however, response functions are more complex, exacerbating uncertainty in larger models. Spatial autocovariates help describe fine-scale patterns of occurrence and significantly improve explained deviance, though if important environmental constraints are omitted then model stability and explanatory power can be compromised. We conclude that the best modelling practice is contingent both on the intentions of the analyst (explanation or prediction) and on the quality of distribution data; generalised additive models have potential to provide valuable information for conservation in the EAMs, but methods must be carefully considered, particularly if occurrence data are scarce. Full results and details of all species models are supplied in an online Appendix. (C) 2008 Elsevier B.V. All rights reserved

    Resource limitation modulates the fate of dissimilated nitrogen in a dual-pathway Actinobacterium

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    Respiratory ammonification and denitrification are two evolutionarily unrelated dissimilatory nitrogen (N) processes central to the global N cycle, the activity of which is thought to be controlled by carbon (C) to nitrate (NO₃⁻) ratio. Here we find that Intrasporangium calvum C5, a novel menaquinone-based dual-pathway denitrifier/respiratory ammonifier, disproportionately utilizes ammonification rather than denitrification when grown under carbon or nitrate limitation, not C:NO3- ratio. Instead, C:NO₃⁻ ratio is a confounding variable for resource limitation. We find that the protein atomic composition for denitrification modules (NirK) are significantly cost minimized for C and N compared to ammonification modules (NrfA), indicating that resource limitation is a major selective pressure imprinted in the architecture of these proteins. The evolutionary precedent for these findings suggests ecological and biogeochemical importance as evidenced by higher growth rates when I. calvum grows predominantly using its ammonification pathway and by assimilating its end-product (ammonium) for growth under ammonium-deplete conditions. Genomic analysis of I. calvum further reveals a versatile ecophysiology to cope with nutrient stress and redox conditions. Metabolite and transcriptional profiles during growth indicate that transcript abundances encoding for its nitrite reducing enzyme modules, NrfAH and NirK, significantly increase in response to nitrite production. Mechanistically, our results suggest that pathway selection is driven by intracellular redox potential (redox poise), which may be lowered during resource limitation, thereby decreasing catalytic activity of upstream electron transport steps needed for denitrification enzymes. Our work advances our understanding of the biogeochemical flexibility of N-cycling organisms, pathway evolution, and ecological food-webs
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