Integrated assurance assessment of a reconfigurable digital flight control system

The integrated application of reliability, failure effects and system simulator methods in establishing the airworthiness of a flight critical digital flight control system (DFCS) is demonstrated. The emphasis was on the mutual reinforcement of the methods in demonstrating the system safety

Mmm --- Popcorn!

Popcorn has been a favorite American treat for many years. Over 300 million pounds were sold in the United States in 1956. If this 300 million pounds were popped all at once, it would fill more than 3,500 boxcars and make up a freight train that would reach from Council Bluffs to Cedar Rapids

Convocation

The origins of phenotypic variation within mimetic Heliconius butterflies have long fascinated biologists and naturalists. However, the evolutionary processes that have generated this extraordinary diversity remain puzzling. Here we examine intraspecific variation across Heliconius cydno diversification and compare this variation to that within the closely related H. melpomene and H. timareta radiations. Our data, which consist of both mtDNA and genome scan from nearly 2250 AFLP loci, reveal a complex history of differentiation and admixture at different geographic scales. Both mtDNA and AFLP phylogenies suggest that H. timareta and H. cydno are probably geographic extremes of the same radiation that likely diverged from H. melpomene during the Pliocene-Pleistocene boundary. MtDNA suggest that this radiation originated in Central America or the Northwestern region of South America, with a subsequent colonization of the eastern and western slopes of the Andes. Our genome-scan data indicate significant admixture among sympatric H. cydno/H.timareta and H. melpomene populations across the extensive geographic ranges of the two radiations. Within H. cydno, both mtDNA and AFLP data indicate significant population structure at local scales, with strong genetic differences even among adjacent H. cydno color pattern races. These genetic patterns highlight the importance of past geoclimatic events, intraspecific gene flow, and local population differentiation in the origin and establishment of new adaptive forms

Extreme long-distance dispersal of the lowland tropical rainforest tree Ceiba pentandra L. (Malvaceae) in Africa and the Neotropics

Many tropical tree species occupy continental expanses of rainforest and flank dispersal barriers such as oceans and mountains. The role of long-distance dispersal in establishing the range of such species is poorly understood. In this study, we test vicariance hypotheses for range disjunctions in the rainforest tree Ceiba pentandra , which is naturally widespread across equatorial Africa and the Neotropics. Approximate molecular clocks were applied to nuclear ribosomal [ITS (internal transcribed spacer)] and chloroplast ( psb B- psb F) spacer DNA sampled from 12 Neotropical and five West African populations. The ITS ( N  = 5) and psb B- psb F ( N  = 2) haplotypes exhibited few nucleotide differences, and ITS and psb B- psb F haplotypes were shared by populations on both continents. The low levels of nucleotide divergence falsify vicariance explanations for transatlantic and cross-Andean range disjunctions. The study shows how extreme long-distance dispersal, via wind or marine currents, creates taxonomic similarities in the plant communities of Africa and the Neotropics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71417/1/j.1365-294X.2007.03341.x.pd

Polyphyly and gene flow between non-sibling Heliconius species

BACKGROUND: The view that gene flow between related animal species is rare and evolutionarily unimportant largely antedates sensitive molecular techniques. Here we use DNA sequencing to investigate a pair of morphologically and ecologically divergent, non-sibling butterfly species, Heliconius cydno and H. melpomene (Lepidoptera: Nymphalidae), whose distributions overlap in Central and Northwestern South America. RESULTS: In these taxa, we sequenced 30–45 haplotypes per locus of a mitochondrial region containing the genes for cytochrome oxidase subunits I and II (CoI/CoII), and intron-spanning fragments of three unlinked nuclear loci: triose-phosphate isomerase (Tpi), mannose-6-phosphate isomerase (Mpi) and cubitus interruptus (Ci) genes. A fifth gene, dopa decarboxylase (Ddc) produced sequence data likely to be from different duplicate loci in some of the taxa, and so was excluded. Mitochondrial and Tpi genealogies are consistent with reciprocal monophyly, whereas sympatric populations of the species in Panama share identical or similar Mpi and Ci haplotypes, giving rise to genealogical polyphyly at the species level despite evidence for rapid sequence divergence at these genes between geographic races of H. melpomene. CONCLUSION: Recent transfer of Mpi haplotypes between species is strongly supported, but there is no evidence for introgression at the other three loci. Our results demonstrate that the boundaries between animal species can remain selectively porous to gene flow long after speciation, and that introgression, even between non-sibling species, can be an important factor in animal evolution. Interspecific gene flow is demonstrated here for the first time in Heliconius and may provide a route for the transfer of switch-gene adaptations for Müllerian mimicry. The results also forcefully demonstrate how reliance on a single locus may give an erroneous picture of the overall genealogical history of speciation and gene flow

Effect of Pivot Point on Aerodynamic Force and Vortical Structure of Pitching Flat Plate Wings

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106512/1/AIAA2013-792.pd

Hierarchy Theory of Evolution and the Extended Evolutionary Synthesis: Some Epistemic Bridges, Some Conceptual Rifts

Contemporary evolutionary biology comprises a plural landscape of multiple co-existent conceptual frameworks and strenuous voices that disagree on the nature and scope of evolutionary theory. Since the mid-eighties, some of these conceptual frameworks have denounced the ontologies of the Modern Synthesis and of the updated Standard Theory of Evolution as unfinished or even flawed. In this paper, we analyze and compare two of those conceptual frameworks, namely Niles Eldredge’s Hierarchy Theory of Evolution (with its extended ontology of evolutionary entities) and the Extended Evolutionary Synthesis (with its proposal of an extended ontology of evolutionary processes), in an attempt to map some epistemic bridges (e.g. compatible views of causation; niche construction) and some conceptual rifts (e.g. extra-genetic inheritance; different perspectives on macroevolution; contrasting standpoints held in the “externalism–internalism” debate) that exist between them. This paper seeks to encourage theoretical, philosophical and historiographical discussions about pluralism or the possible unification of contemporary evolutionary biology

Isolated Gust Generation for the Investigation of Airfoil-Gust Interaction

As part of an effort to examine the impact of vortical gusts on airfoils, a simple gust generator has been built and investigated. This consists of a heaving at plate capable of following a specifed transverse trajectory across a water tunnel. The relationship between the trajectory and the properties of the gusts that are shed downstream is characterized for non-periodic heaving motion described by Eldredge's smooth motion equation. PIV experiments show that the circulation of the vortical gust is proportional to the heaving speed of the plate. Tests with a downstream NACA 0018 airfoil demonstrate repeatable forces in response to the produced gusts

The Roots of Diversity: Below Ground Species Richness and Rooting Distributions in a Tropical Forest Revealed by DNA Barcodes and Inverse Modeling

F. Andrew Jones is with the Smithsonian Tropical Research Institute, David L. Erickson is with the Smithsonian Institution, Moises A. Bernal is with the Smithsonian Tropical Research Institute and UT Austin, Eldredge Bermingham is with the Smithsonian Tropical Research Institute, W. John Kress is with the Smithsonian Institution, Edward Allen Herre is with the Smithsonian Tropical Research Institute, Helene C. Muller-Landau is with the Smithsonian Tropical Research Institute, Benjamin L. Turner is with the Smithsonian Tropical Research Institute.Background -- Plants interact with each other, nutrients, and microbial communities in soils through extensive root networks. Understanding these below ground interactions has been difficult in natural systems, particularly those with high plant species diversity where morphological identification of fine roots is difficult. We combine DNA-based root identification with a DNA barcode database and above ground stem locations in a floristically diverse lowland tropical wet forest on Barro Colorado Island, Panama, where all trees and lianas >1 cm diameter have been mapped to investigate richness patterns below ground and model rooting distributions. Methodology/Principal Findings -- DNA barcode loci, particularly the cpDNA locus trnH-psba, can be used to identify fine and small coarse roots to species. We recovered 33 species of roots from 117 fragments sequenced from 12 soil cores. Despite limited sampling, we recovered a high proportion of the known species in the focal hectare, representing approximately 14% of the measured woody plant richness. This high value is emphasized by the fact that we would need to sample on average 13 m2 at the seedling layer and 45 m2 for woody plants >1 cm diameter to obtain the same number of species above ground. Results from inverse models parameterized with the locations and sizes of adults and the species identifications of roots and sampling locations indicates a high potential for distal underground interactions among plants. Conclusions -- DNA barcoding techniques coupled with modeling approaches should be broadly applicable to studying root distributions in any mapped vegetation plot. We discuss the implications of our results and outline how second-generation sequencing technology and environmental sampling can be combined to increase our understanding of how root distributions influence the potential for plant interactions in natural ecosystems.FAJ acknowledges the support of a Tupper postdoctoral fellowship in tropical biology and the National Science Foundation (DEB 0453665). Funding was provided by the Smithsonian Institution Global Earth Observatory, the Smithsonian Tropical Research Institute/Center for Tropical Forest Sciences endowment fund, and the Smithsonian Tropical Research Institute/Frank Levinson fund. We would like to thank Autoridad Nacional del Ambiente and the Smithsonian Tropical Research Institute for processing research permits. We thank S. Hubbell and R. Condit for access to plot data, S. Schnitzer for liana census data (NSF DEB 0613666), and L. Comita and S. Hubbell for access to seedling data (NSF DEB 0075102 and DEB 0823728). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Marine Scienc

Phase I Study of Ipilimumab Combined with Whole Brain Radiation Therapy or Radiosurgery for Melanoma Patients with Brain Metastases

Purpose: We performed a phase I study to determine the maximum tolerable dose (MTD) and safety of ipilimumab with stereotactic radiosurgery (SRS) or whole brain radiotherapy (WBRT) in patients with brain metastases (BM) from melanoma. Methods: Based on intracranial (IC) disease burden, patients were treated with WBRT (Arm A) or SRS (Arm B). Ipilimumab starting dose was 3 mg/kg (every 3 weeks, starting on day 3 of WBRT or 2 days after SRS). Ipilimumab was escalated to 10 mg/kg using a two-stage, 3+3 design. The primary endpoint was to determine the MTD of ipilimumab combined with radiotherapy. Secondary endpoints were overall survival (OS), IC and extracranial (EC) control, progression free survival (PFS), and toxicity. This trial is regis- tered with ClinicalTrials.gov, number NCT01703507. Results: Characteristics of the 16 patients enrolled between 2011 and 2014 were: mean age, 60; median BM, 2 (1 to \u3e10); number with EC disease, 13 (81%). Treatment included WBRT (n=5), SRS (n=11), ipilimumab 3mg/kg (n=7), 10 mg/kg (n=9). Median follow-up was 8 months (Arm A) and 10.5 months (Arm B). There were 21 grade 1-2 neuro- toxic effects with no dose-limiting toxicities (DLTs). One patient experienced grade 3 neurotoxicity prior to ipilimumab administration. Ten additional grade 3 toxicities were reported with gastrointestinal (n=5, 31%) as the most common. There were no grade 4/5 toxicities. Median PFS and OS, respectively, in Arm A were 2.5 months and 8 months, and in Arm B were 2.1 months and not reached. Conclusion: Concurrent ipilimumab 10 mg/kg with SRS is safe. The WBRT arm was closed early due to slow accrual, but demonstrated safety with ipilimumab 3 mg/kg. No patient experienced DLT. Larger studies with ipilimumab 10 mg/kg and SRS are warranted