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The identification of the causative genetic variants in quantitative trait loci (QTL) influencing phenotypic traits is challenging, especially in crosses between outbred strains. We have previously identified several QTL influencing tameness and aggression in a cross between two lines of wild-derived, outbred rats (Rattus norvegicus) selected for their behavior towards humans. Here, we use targeted sequence capture and massively parallel sequencing of all genes in the strongest QTL in the founder animals of the cross. We identify many novel sequence variants, several of which are potentially functionally relevant. The QTL contains several regions where either the tame or the aggressive founders contain no sequence variation, and two regions where alternative haplotypes are fixed between the founders. A re-analysis of the QTL signal showed that the causative site is likely to be fixed among the tame founder animals, but that several causative alleles may segregate among the aggressive founder animals. Using a formal test for the detection of positive selection, we find 10 putative positively selected regions, some of which are close to genes known to influence behavior. Together, these results show that the QTL is probably not caused by a single selected site, but may instead represent the joint effects of several sites that were targets of polygenic selection. more...

In light of the significance that ecosystem service research is likely to play in linking conservation activities and human welfare, systematic approaches to measuring, modeling and mapping ecosystem services (and their value to society) are sorely needed. In this paper we outline one such approach, which we developed in order to understand the links between the functioning of the ecosystems of Tanzania’s Eastern Arc Mountains and their impact on human welfare at local, regional and global scales. The essence of our approach is the creation of a series of maps created using field-based or remotely sourced data, data-driven models, and socio-economic scenarios coupled with rule-based assumptions. Here we describe the construction of this spatial information and how it can help to shed light on the complex relationships between ecological and social systems. There are obvious difficulties in operationalizing this approach, but by highlighting those which we have encountered in our own case-study work, we have also been able to suggest some routes to overcoming these impediments. more...

Global efforts to conserve biodiversity have the potential to deliver economic benefits to people (i.e., "ecosystem services"). However, regions for which conservation benefits both biodiversity and ecosystem services cannot be identified unless ecosystem services can be quantified and valued and their areas of production mapped. Here we review the theory, data, and analyses needed to produce such maps and find that data availability allows us to quantify imperfect global proxies for only four ecosystem services. Using this incomplete set as an illustration, we compare ecosystem service maps with the global distributions of conventional targets for biodiversity conservation. Our preliminary results show that regions selected to maximize biodiversity provide no more ecosystem services than regions chosen randomly. Furthermore, spatial concordance among different services, and between ecosystem services and established conservation priorities, varies widely. Despite this lack of general concordance, "win-win" areas - regions important for both ecosystem services and biodiversity - can be usefully identified, both among ecoregions and at finer scales within them. An ambitious interdisciplinary research effort is needed to move beyond these preliminary and illustrative analyses to fully assess synergies and trade-offs in conserving biodiversity and ecosystem services. more...

Background: Nonsense-mediated mRNA decay (NMD) is a eukaryotic mRNA surveillance mechanism that detects and degrades mRNAs with premature termination codons (PTC+ mRNAs). In mammals, a termination codon is recognized as premature if it lies more than about 50 nucleotides upstream of the final intron position. More than a third of reliably inferred alternative splicing events in humans have been shown to result in PTC+ mRNA isoforms. As the mechanistic details of NMD have only recently been elucidated, we hypothesized that many PTC+ isoforms may have been cloned, characterized and deposited in the public databases, even though they would be targeted for degradation in vivo. Results: We analyzed the human alternative protein isoforms described in the SWISS-PROT database and found that 144 (5.8% of 2,483) isoform sequences amenable to analysis, from 107 (7.9% of 1,363) SWISS-PROT entries, derive from PTC+ mRNA. Conclusions: For several of the PTC+ isoforms we identified, existing experimental evidence can be reinterpreted and is consistent with the action of NMD to degrade the transcripts. Several genes with mRNA isoforms that we identified as PTC+ - calpain-10, the CDC-like kinases (CLKs) and LARD - show how previous experimental results may be understood in light of NMD. more...

The technique of Surface Brillouin Spectroscopy is attracting considerable attention for the non-destructive characterization of near-surface properties that depend upon the elastic behaviour. These include surface strengthening, delamination in metallised layers and structural changes near surfaces. We here present a study of the chemical strengthening of glass. SBS measurements of surface acoustic wave (SAW) velocity in glasses strengthened by the exchange of K+ for Na+ ions were carried out using the Bede BriSc instrument. The study of surface acoustic waves on a transparent material such as glass was made possible by depositing a thin layer of aluminium on the glass surface. At a working frequency of 20 GHz, the optimum thickness of the layer was found to be 30 nm. The replacement of Na+ by K+ ions that takes place during the treatment of the glass causes near-surface modifications of both density and elastic constants. An increase of 3.8% in density due to the replacement of light Na+ ions by heavier K+ ions at the surface could account only for a 1.9% decrease in the surface acoustic wave velocity. Residual stresses were estimated to have a negligible effect on surface acoustic wave velocity. At the same time a 2.8+/-0.4% decrease in the surface acoustic wave velocity due to the ion-exchange process was observed by SBS. This result suggests that a significant part of the surface acoustic wave (SAW) velocity change should be attributed to variations in the elastic constants (approximately 1.8%) and agrees well with independent estimates of the Young's modulus (E) and shear modulus (C-44) changes caused by replacing the Na+ ions by K+ ions during the process. more...

The purpose of the present research is to use innovative optical techniques and superior signal capture and processing systems to determine the waveforms, frequency spectra, and propagational behavior of the acoustic emission signals generated by the various mechanical deformation mechanisms leading to failure of metal alloys of prime importance to naval structures. The ultimate goal of this research is to absolutely determine the degree to which precise characterization of the acoustic emission signals can serve to remotely assess the severity of mechanical damage and give early warning of impending failure. Experiments were performed using a modified piezoelectric transducer, a Fizeau type interferometer, and a modified Michelson interferometer. Acoustic emission events were generated by pulling microtensile specimens in an extremely quiet microtensile machine and by the brittle, step unloading fracture of glass capillary tubes on the surface of test specimens possessing different geometries. All acoustic emission event waveforms were recorded by a high speed transient recorder and stored on magnetic mini-diskettes for analysis on a high speed digital computer and for future propagational behavior and waveform analysis. Specimens which were pulled on the microtensile machine were examined under optical and scanning electron microscopes to determine a point by point correlation between acoustic emission events and microstructural changes. more...

The purpose of the present research is to optimize existing ultrasonic and acoustic emission techniques and to investigate new ones for early detection of fatigue damage in aluminum alloys used in aircraft construction. An ultrasonic pulse-echo system was used during fatigue cycling to record conventional A-scan wave forms as well as to monitor ultrasonic attenuation on 7075-T651 aluminum alloy specimens possessing different surface conditions. In addition, acoustic emission signals were recorded simultaneously with the ultrasonic measurements on each test specimen using two different acoustic emission systems. The task of correlating evidence of cumulative fatigue damage and acoustic emission data was approached by the use of long term true-rms averaging of the system output and frequency domain analysis of acoustic emission signals recorded at selected intervals throughout the test. The integrity of the data was verified by independent electronic testing of the instrumentation, in situ eddy current and visual inspection, and metallographic examination. (Author) more...

A method of choosing alternative mixes of instruments is presented. The mix of instruments is chosen based on total discounted cost for the life of the system. The optimum mix is chosen using linear programming techniques. The sample problem solved chooses the optimum mix of tracking telescopes for White Sands Missile Range. The information used for this analysis was collected in the summer of 1976. (Author) more...

Simultaneous direct measurements taken in elevation, azimuth and range for independent instrumentation sources, when aggregated and reduced can often yield sensible estimates. However, strong aberrations and inconsistencies in the estimates derived from data reduction have been known to occur. Two particular factors are investigated in order to partially explain theoretically these elusive deviations and to establish some cause and effect relationship. The first set of factors relates to the relative geometric siting of the instruments as well as the type of measurements recorded. Typical measurements which would be conducive to such aberrations are discussed. The second set of factors relates to the selection of a frame of reference for aximuthal measurement. It is shown that coordinate selection can play for certain types of measurements a significant role in multiplying the GDOP by severalfold from a rationally established minimum basis. (Author), Proceedings of the National Aerospace Electronics Conference. more...

Accurate estimates of Cartesian coordinates of the existing range instrumentation systems depend on such factors as target position, number of instruments, location of instruments, and instrument accuracy. This report analyses the problem of instrument location when the station configuration is asymmetrical. This is an extension of a previous investigation and covers a more general class of problems. This study has shown that, for angle measuring devices, the error estimate is functionally related to the azimuth reference used when the station locations are asymmetrical. Expressions are developed for several classes of site geometries. Optimal site geometries have been identified within a certain class of site geometries. (Author) more...

The report discusses a Hybrid Navigational System for low altitude airborne tracking and for accurate calibration of range instrumentation equipment. System consists of an airborne inertial platform, transponder for Distance Measuring Equipment (DME) interrogation (providing range and range measurements), barometer type altimeter or a phase array radar, an airborne navigational and filtering computer, and ground based DME. Inertial platform may or may not be torqued. The heart of the system is the navigational computer and the Kalman filter. A reference trajectory is generated by the cubic spline method and along with proper coordinate conversion, the doppler data, range measurements data, barometer data, and the inertial measurement unit (IMU) accelerometer measurements corrupted with noise are simulated. Navigational equations, error equations, and the Kalman filter algorithm are mechanized. more...

The use of ultrasonic testing for the inspection of weldments in titanium alloys requires careful acoustical characterization of the materials and weldments in question. In the first part of the present work various ultrasonic tests were conducted on a series of test specimens of titanium alloy weldments and base plate material. Ultrasonic wave velocity and attenuation measurements were made in the low megahertz frequency range using both longitudinal and shear waves. Both the ultrasonic wave velocity and attenuation were observed to be lower in the weld region than in the base metal. Information provided by x-ray analysis helped to account for the observed wave velocity behavior. Changes in the attentuation were correlated tto microstructural variations and hardness measurements in the weld region and base metal. The second stage of the research focused on the problem of dissolved gas contamination of Ti-6211 welded joints. In order to evaluate the feasibility of ultrasonic testing for detecting quantitatively the presence of interstitial gas contamination in weldments of Ti-6211, ultrasonic wave velocity and ultrasonic attenuation measurements were performed on a series of five specimens with nominal oxygen levels of 0.1, 0.2, 0.3, 0.4, and 0.5 percent by weight. Careful density measurements in addition to the ultrasonic wave velocity data enabled accurate determination of elastic moduli. (Author), This article is from the Proceedings of the Workshop on Nondestructive Evaluation (NDE) of Titanium Alloys Held on 2-4 Feb 82 at the Naval Research Laboratory, Underwater Sound Reference Detachment, Orlando, FL., AD-A147 626, p71 - 95. more...