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Sensenig A.T.,Tabor College | Lorentz K.A.,University of Akron | Kelly S.P.,University of Akron | Blackledge T.A.,University of Akron
Journal of the Royal Society Interface | Year: 2012

The kinetic energy of flying insect prey is a formidable challenge for orb-weaving spiders. These spiders construct two-dimensional, round webs from a combination of stiff, strong radial silk and highly elastic, glue-coated capture spirals. Orb webs must first stop the flight of insect prey and then retain those insects long enough to be subdued by the spiders. Consequently, spider silks rank among the toughest known biomaterials. The large number of silk threads composing a web suggests that aerodynamic dissipation may also play an important role in stopping prey. Here, we quantify energy dissipation in orb webs spun by diverse species of spiders using data derived from high-speed videos of web deformation under prey impact. By integrating video data with material testing of silks, we compare the relative contributions of radial silk, the capture spiral and aerodynamic dissipation. Radial silk dominated energy absorption in all webs, with the potential to account for approximately 100 per cent of the work of stopping prey in larger webs. The most generous estimates for the roles of capture spirals and aerodynamic dissipation show that they rarely contribute more than 30 per cent and 10 per cent of the total work of stopping prey, respectively, and then only for smaller orb webs. The reliance of spider orb webs upon internal energy absorption by radial threads for prey capture suggests that the material properties of the capture spirals are largely unconstrained by the selective pressures of stopping prey and can instead evolve freely in response to alternative functional constraints such as adhering to prey. © 2012 The Royal Society. Source


Yisak H.,Tabor College | Gobena T.,Health Science University | Mesfin F.,Health Science University
BMC Pediatrics | Year: 2015

Background: Under nutrition is one of the major causes of health problems among children under five years old in Ethiopia. Though the problem of under nutrition has decreased in the country, it is still continuing as one of the major causes of mortality of children under five. Studies have shown that the magnitude and related factors of under nutrition are varied in different agro-ecological settings of the country. Thus it is indispensable to assess the nature of the problem at community level. The objective of this study was to assess the extent of under nutrition and related factors among children under five years in Haramaya district, eastern Ethiopia. Methods: A community based cross sectional study was conducted in Haramaya district from December 1, 2012 to January 30, 2013 and Multi-stage stratified systematic random sampling technique was used to select the study subjects. A total of 791 study subjects were included in the study. Data were collected using face-to-face interview and anthropometric measurements. World Health Organization (WHO) Anthro software was used to convert nutritional data indices from anthropometric measurement into Z-scores, and Multivariate logistic regression model with an enter method was used to determine the predictors of under nutrition. Results: The study indicated that prevalence of stunting, wasting and underweight among children under five years old were 45.8 %, 10.7 % and 21 % respectively. Children in rural Kebeles with Adjusted odd ratio (AOR) =2.45, 95 % CI(1.25-6.66), children who were 6 and above birth order (AOR =1.992, 95 % CI( 1.05-3.77)), and children who were used to live with households having two and more under five children (AOR = 1.81, 95 % CI( 1.19-2.7)) were more stunted than their counterparts. Children in the lowland Kebeles, (AOR = 3.29, 95 % CI( 1.2-8.8)) and children having diarrhea, (AOR = 2.48, 95 % CI(1.28-4.78)); mothers with Body mass index (BMI) < 18.5 (AOR = 2.17, 95 % CI(1.17-3.81)); mothers who did not have ANC visit during pregnancy (AOR = 3.47, 95 % CI (1.49-7.8) ) and with birth order of 4 to 5 children (AOR = 3.08, 95 % CI (1.11-8.5)), were more likely to be underweight than their counterparts. Moreover, male children (AOR = 2.37, 95 % CI (1.19-4.7)), children who were served food with family (AOR = 2.3, 95 % CI (1.14- 4.9)), children who had fever, (AOR = 2.9, 95 % CI (1.16-7.2)), were more likely to be wasted than their counterparts. Conclusions: This study indicated that nearly half of the children under five years in the study area were stunted. Thus, a large number of children had poor nutritional history or growth failure. Furthermore, underweight and wasting were significantly high. The problem can be addressed by targeting children since their early ages and by conducting tailored nutrition education to mothers or caretakers to improve the nutritional status of their children. © 2015 Yisak et al. Source


Kelly S.P.,University of Akron | Sensenig A.,Tabor College | Lorentz K.A.,University of Akron | Blackledge T.A.,University of Akron
Zoology | Year: 2011

Orb-weaving spiders depend upon their two-dimensional silk traps to stop insects in mid flight. While the silks used to construct orb webs must be extremely tough to absorb the tremendous kinetic energy of insect prey, webs must also minimize the return of that energy to prey to prevent insects from bouncing out of oscillating webs. We therefore predict that the damping capacity of major ampullate spider silk, which forms the supporting frames and radial threads of orb webs, should be evolutionarily conserved among orb-weaving spiders. We test this prediction by comparing silk from six diverse species of orb spiders. Silk was taken directly from the radii of orb webs and a Nano Bionix test system was used either to sequentially extend the silk to 25% strain in 5% increments while relaxing it fully between each cycle, or to pull virgin silk samples to 15% strain. Damping capacity was then calculated as the percent difference in loading and unloading energies. Damping capacity increased after yield for all species and typically ranged from 40 to 50% within each cycle for sequentially pulled silk and from 50 to 70% for virgin samples. Lower damping at smaller strains may allow orb webs to withstand minor perturbations from wind and small prey while still retaining the ability to capture large insects. The similarity in damping capacity of silk from the radii spun by diverse spiders highlights the importance of energy absorption by silk for orb-weaving spiders. © 2011 Elsevier GmbH. Source


Sensenig A.T.,Tabor College | Agnarsson I.,University of Puerto Rico at San Juan | Blackledge T.A.,University of Akron
Journal of Zoology | Year: 2011

Body size increases greatly during ontogeny in most animals and is often accompanied by dramatic shifts in foraging strategies and hence food resources. Orb-weaver spiders provide an interesting case, where a relatively homogeneous foraging strategy, aerial silk webs, is employed across all ontogenetic stages. Orb webs are spun soon after spiders emerge from the egg sac through growth of up to two orders of magnitude in body size. The sizes of prey targeted by the spiders are also likely to increase as spiders develop. Here, we examine how relative silk investment, web architecture, and the material properties of silk in webs change during ontogeny in the orb-weaver Neoscona arabesca. We also quantify two emergent properties of web performance - prey stopping potential and stickiness. We find that silk investment increases isometrically with body size, with the exception of greater than expected glue production in larger spiders. Larger spiders spin larger webs, with smaller radii, but the increased volume of all silk types and greater toughness of the capture spiral silk result in the isometric scaling of stopping potential. The strength and toughness of sticky capture spiral thread increases with diameter and hence also with ontogeny, a size scaling pattern that mirrors an evolutionary pattern across spider species. Dragline thread material properties do not change over ontogeny. The improved material properties of capture spiral threads and the increased absolute stopping potential of webs are consistent with the hypothesis that rare, large prey items play a crucial role in spiders reaching adulthood and in maximizing fecundity of female orb-weaver spiders. © 2011 The Authors. Journal of Zoology © 2011 The Zoological Society of London. Source


Cox J.A.,Tabor College
Journal of Religion, Disability and Health | Year: 2011

Leviticus 21:16-23 has historically been used negatively with regard to people with disabilities and ministry. The aim of this discussion is to present the Levitical restriction on priests with disabilities in a positive light. This goal is achieved by presenting a reading of Leviticus 21:16-23 as an enacted parable. An enacted parable is a parabolic action that involves the person of the one who enacts it. In the case of Leviticus 21:16-23, the enacted parable concerns the way in which the blemished priests provided a visual demonstration of the holiness of Yahweh. © Taylor & Francis Group, LLC. Source

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