A Bivariate Hypothesis Testing Approach for Mapping the Trait-Influential Gene

The linkage disequilibrium (LD) based quantitative trait loci (QTL) model involves two indispensable hypothesis tests: the test of whether or not a QTL exists, and the test of the LD strength between the QTaL and the observed marker. The advantage of this two-test framework is to test whether there is an influential QTL around the observed marker instead of just having a QTL by random chance. There exist unsolved, open statistical questions about the inaccurate asymptotic distributions of the test statistics. We propose a bivariate null kernel (BNK) hypothesis testing method, which characterizes the joint distribution of the two test statistics in two-dimensional space. The power of this BNK approach is verified by three different simulation designs and one whole genome dataset. It solves a few challenging open statistical questions, closely separates the confounding between ‘linkage’ and ‘QTL effect’, makes a fine genome division, provides a comprehensive understanding of the entire genome, overcomes limitations of traditional QTL approaches, and connects traditional QTL mapping with the newest genotyping technologies. The proposed approach contributes to both the genetics literature and the statistics literature, and has a potential to be extended to broader fields where a bivariate test is needed

Used-habitat calibration plots: a new procedure for validating species distribution, resource selection, and step-selection models

“Species distribution modeling” was recently ranked as one of the top five “research fronts” in ecology and the environmental sciences by ISI's Essential Science Indicators (Renner and Warton 2013), reflecting the importance of predicting how species distributions will respond to anthropogenic change. Unfortunately, species distribution models (SDMs) often perform poorly when applied to novel environments. Compounding on this problem is the shortage of methods for evaluating SDMs (hence, we may be getting our predictions wrong and not even know it). Traditional methods for validating SDMs quantify a model's ability to classify locations as used or unused. Instead, we propose to focus on how well SDMs can predict the characteristics of used locations. This subtle shift in viewpoint leads to a more natural and informative evaluation and validation of models across the entire spectrum of SDMs. Through a series of examples, we show how simple graphical methods can help with three fundamental challenges of habitat modeling: identifying missing covariates, non-linearity, and multicollinearity. Identifying habitat characteristics that are not well-predicted by the model can provide insights into variables affecting the distribution of species, suggest appropriate model modifications, and ultimately improve the reliability and generality of conservation and management recommendations

Design and assembly sequence analysis of option 3 for CETF reference space station

A design and assembly sequence was conducted on one option of the Dual Keel Space Station examined by a NASA Critical Evaluation Task Force to establish viability of several variations of that option. A goal of the study was to produce and analyze technical data to support Task Force decisions to either examine particular Option 3 variations in more depth or eliminate them from further consideration. An analysis of the phasing assembly showed that use of an Expendable Launch Vehicle in conjunction with the Space Transportation System (STS) can accelerate the buildup of the Station and ease the STS launch rate constraints. The study also showed that use of an Orbital Maneuvering Vehicle on the first flight can significantly benefit Station assembly and, by performing Station subsystem functions, can alleviate the need for operational control and reboost systems during the early flights. In addition to launch and assembly sequencing, the study assessed stability and control, and analyzed node-packaging options and the effects of keel removal on the structural dynamics of the Station. Results of these analyses are presented and discussed

Comparison of bare root and RPM seedling production technologies : implications for agroforestry

Paper presented at the 12th North American Agroforesty Conference, which was held June 4-9, 2011 in Athens, Georgia.In Ashton, S. F., S.W. Workman, W.G. Hubbard and D.J. Moorhead, eds. Agroforestry: A Profitable Land Use. Proceedings, 12th North American Agroforestry Conference, Athens, GA, June 4-9, 2011.'Root Production Method' (RPM) technology significantly increases the development of root systems in containerized seedlings. As an alternative to bare root seedlings, RPM seedlings have been promoted as a method to increase growth and survivability of hardwood trees. However, few scientific studies have been conducted that would support these claims. Three oak species (Quercus spp.) were the focus of this study. Seed was collected from a single mother tree of black oak (Quercus velutina, Lam.), white oak (Quercus alba Linn.), and swamp white oak (Quercus bicolor Willd.). Half of the seed from each mother tree was used to produce RPM, the other half bare root stock, (i.e. half siblings) which were planted in the fall (RPM) of 1996 or spring (bare root) of 1997 at the Horticulture and Agroforestry Research Center, New Franklin, MO. After 14 years in the field, bare root and RPM trees were harvested for each species and total above ground weight was recorded. Statistical analysis of the data was conducted using least-square means and a method of orthogonal contrasts to determine if significant differences existed between the biomass of bare root and RPM trees. Results showed that the RPM trees had up to twice as much above-ground biomass weight as the bare root trees of the same age. Implications of this study suggest that RPM trees could be used in agroforestry practices as a way of increasing carbon sequestration and biomass production. In addition, the significant increase in growth that was observed should serve to enhance interest in adopting agroforestry practices.Larry D. Godsey (1), John P. Dwyer (2), W. Dusty Walter (1) and Harold 'Gene' Garrett (1) ; 1. University of Missouri Center for Agroforestry, Columbia, MO. 2. Department of Forestry, School of Natural Resources, University of Missouri-Columbia,Columbia, MO.Includes bibliographical references

The Anderson-Mott transition induced by hole-doping in Nd1-xTiO3

The insulator/metal transition induced by hole-doping due to neodymium vacancies of the Mott- Hubbard antiferromagnetic insulator, Nd1-xTiO3, is studied over the composition range 0.010(6) < x < 0.243(10). Insulating p-types conduction is found for x < 0.071(10). Anderson localization in the presence of a Mott-Hubbard gap, is the dominant localization mechanism for the range of 0.074(10) < x < 0.089(1) samples. For x < 0.089(1), n-type conduction is observed and the activation energy extrapolates to zero by x < 0.1. The 0.095(8) < x < 0.203(10) samples are Fermi-liquid metals and the effects of strong electronic correlations are evident near the metal-to-insulator boundaries in features such as large Fermi liquid T2 coefficients. For 0.074(9) < x < 0.112(4), a weak negative magnetoresistance is found below ~ 15 K and it is attributed to the interaction of conduction electrons with Nd3+ magnetic moments. Combining information from our companion study of the magnetic properties of Nd1-xTiO3 solid solution, a phase diagram is proposed. The main conclusions are that long range antiferromagnetic order disappears before the onset of metallic behavior and that the Anderson-Mott transition occurs over a finite range of doping levels. Our results differ from conclusions drawn from a similar study on the hole doped Nd1-xCaxTiO3 system which found the co-existence of antiferromagnetic order and metallic behavior and that the Mott transition occurs at a discrete doping level

A Nonlinear Transmission Line Model for Simulating Distributed SIS Frequency Multipliers

Superconductor/insulator/superconductor (SIS) jun-ctions have extremely nonlinear electrical properties, which makes them ideal for a variety of applications, including heterodyne mixing and frequency multiplication. With SIS mixers, the SIS junctions normally have circular cross sections, but they can also be fabricated in the form of microstrip transmission lines, known as distributed SIS junctions (DSJs). By using a DSJ as an open-circuit stub, it is possible to create a large SIS junction with a low effective input reactance. This is beneficial for SIS frequency multipliers because their output power is proportional to the area of the junction. It is challenging, however, to simulate the behavior of DSJs because they have to be modeled as transmission lines and the model has to take into account the quasiparticle tunneling current, which is a nonlinear function of the ac voltage. In this article, we present a new nonlinear transmission line model to accurately describe the behavior of DSJs and to simulate the performance of distributed SIS frequency multipliers (DSMs). This model is compared to experimental data from a recent DSM device and good agreement is found between the dc tunneling currents and the output powers at the second harmonic. Based on this success, an improved DSM design is proposed that has a higher output power and a higher conversion efficiency than previous designs.\ua0\ua9 2011-2012 IEEE

Clemson University Retrieval of Explants Program and Registry in Orthopaedics (CU-REPRO)

The Clemson University Retrieval of Explants Program and Registry in Orthopaedics (CU-REPRO) is a student-led creative inquiry program created in 2008. CU-REPRO is a working repository of more than 500 explanted joint replacements collected from cooperative partnerships with 11 hospitals in South Carolina. This program provides an exciting opportunity for students to work with orthopedic surgical teams to collect and process explanted medical devices. This program allows students to explore clinical problems associated with surgical and patient variables, and develop the tools and techniques for systematic evaluation of implant designs, biomaterials, and function. It is one of only a few implant retrieval programs in the country and distinguishes itself by incorporating undergraduate education, biomaterials research and community outreach in its mission. This year, CU-REPRO began research into hip replacements to determine reasons why a subset of explanted femoral stems were received with mid-stem fractures. Review of clinical records revealed that some stems were cut during revision surgery to aid removal while others endured fatigue fractures while in the patients. This semester, the engineering significance of this finding will be explored, as related to loading conditions, stem size and material. The goal is to publish these findings in a suitable orthopaedics journal and make a meaningful scientific contribution. The REPRO team would like to thank the Clemson University Creative Inquiry program for the opportunity to continue to build the growing registry and to expand the program to include research projects