91 research outputs found
Federal Aid in Wildlife Restoration
This report represents a compilation, analysis and summarization of data collected on the South Platte Management Area and deals primarily with game bird data collected by personnel of Project W-37-R. History, general description, and methods of operation are discussed, and recommendations for future operations given.
Briefly, the South Platte Management Area is located in Logan and Sedgwick counties, comprising over 11, 400 acres of state-owned land in four separate segments. The largest segment (more than 12,000 acres of deeded and leased land) lies along the South Platte River from Proctor to Red Lion. This, and a second area of 240 acres, near the town of Sedgwick, known as Sedgwick Bar, were acquired using Federal Aid Funds, primarily for the purpose of providing wintering and resting sites for migratory waterfowl which frequent this section of northeastern Colorado in greater numbers in winter than anywhere else in the state. These areas are used as public shooting grounds during the regular open seasons. Most of the discusssions in this report pertain to these two areas.
The third and fourth segments of the management area are Sand Draw, some ten miles south of Julesburg, and the Smith Property near Crook. Both were acquired to provide all-year habitat for upland game birds, primarily pheasants, with some of the land farmed on a percentage basis and part of the grain left standing for winter feed
Waterfowl - water temperature relations in winter
Submitted to Office of Water Resources Research, U.S. Department of the Interior.Bibliography: page 60.Project A-006-COLO, Grant agreement nos. 14-01-0001-1074, 1625, 3006
Exploring the limits of saving a subspecies: The ethics and social dynamics of restoring northern white rhinos (Ceratotherium simum cottoni)
Abstract The northern white rhino (Ceratotherium simum cottoni) is functionally extinct with only two females left alive. However, cryopreserved material from a number of individuals represents the potential to produce additional individuals using advanced reproductive and genetic rescue technologies and perhaps eventually a population to return to their native range. If this could and were done, how should it be done responsibly and thoughtfully. What issues and questions of a technical, bioethical, and societal nature will it raise that need to be anticipated and addressed? Such issues are explored in this article by an interdisciplinary team assembled to provide context to the northern white rhino project of the San Diego Zoo Global
SYSTEMS ENGINEERING AND ASSURANCE MODELING (SEAM): A WEB-BASED SOLUTION FOR INTEGRATED MISSION ASSURANCE
We present an overview of the Systems Engineering and Assurance Modeling (SEAM) platform, a web-browser-based tool which is designed to help engineers evaluate the radiation vulnerabilities and develop an assurance approach for electronic parts in space systems. The SEAM framework consists of three interconnected modeling tools, a SysML compatible system description tool, a Goal Structuring Notation (GSN) visual argument tool, and Bayesian Net and Fault Tree extraction and export tools. The SysML and GSN sections also have a coverage check application that ensures that every radiation fault identified on the SysML side is also addressed in the assurance case in GSN. The SEAM platform works on space systems of any degree of radiation hardness but is especially helpful for assessing radiation performance in systems with commercial-off-the-shelf (COTS) electronic components
Connecting Mission Profiles and Radiation Vulnerability Assessment
Radiation vulnerability assessment early in spacecraft development is cheaper and faster than in late development phases. RGENTIC and SEAM are two software platforms that can be coupled to provide this type of early assessment. Specifically, RGENTIC is a tool that outputs descriptions of radiation risks based on a selected mission environment and the system’s electronic part portfolio, while SEAM models how radiation-induced faults in electronic parts propagate through a system. In this work, we propose a spacecraft evaluation flow where RGENTIC’s outputs, which are radiation vulnerabilities of electronic parts for a given mission, become inputs to SEAM, resulting in an automatic part-type template palette presented to users so that they can easily begin modeling the occurrence and propagation of radiation-induced faults in their spacecraft. In this context, fault propagation modeling shows how radiation effects impact the spacecraft’s electronics.
The interface between these platforms can be streamlined through the creation of a SEAM global part-type library with templates based on radiation effects in part-type families such as sensors, processors, voltage regulators, and so forth. Several of the part-types defined in RGENTIC have been integrated into SEAM templates. Ultimately, all 66+ part-types from the RGENTIC look-up table will be included in the SEAM global part library. Once accomplished, the part templates can be used to populate each project-specific part library in SEAM, ensuring all RGENTIC’s part-types are represented, and the radiation effects are consistent between the two.
The harmonization process between RGENTIC and SEAM begins as follows: designers input a detailed knowledge of their system and mission into RGENTIC, which then outputs a generic part-type list that associates each part-type with potential radiation concerns. The list is then downloaded in a SEAM-readable file, which SEAM uses to populate the initially blank project with the part templates that correspond to RGENTIC’s output. The final product is a system fault model using a project-specific radiation effect part library.
The radiation effects considered in the part library are associated with three categories of radiation-environment issues: single event effects (SEE), total ionizing dose (TID), and displacement damage dose (DDD). An example part-type is the discrete LED, which has been functionally decomposed into input power and output light. It has a single possible radiation-induced fault that is associated with DDD, which causes degraded brightness and is observed on the output.
Overall, designers will benefit from a coordination of these two tools because it simplifies the initial definition of the project in SEAM. This is especially the case for new users, since the necessary radiation models for their parts are available before modeling commences. Furthermore, starting from a duplicate of an existing project decreases the amount of time and effort required to develop project-specific models. Incorporating RGENTIC’s table of part-types resolves these issues and provides a streamlined process for creating system radiation fault models. Consequently, spacecraft designers can identify radiation problems early in the design cycle and fix them with lower cost and less effort than in later design stages
Methodology for Correlating Historical Degradation Data to Radiation-Induced Degradation System Effects in Small Satellites
When constructing a system-level fault tree to demonstrate device-to-system level radiation degradation, reliability engineers need relevant, device-level failure probabilities to incorporate into reliability models. Deriving probabilities from testing can be expensive and time-consuming, especially if the system is complex. This methodology offers an alternative means of deriving device-level failure probabilities. It uses Bayesian analysis to establish links between historical radiation datasets and failure probabilities. A demonstration system for this methodology is provided, which is a TID response of a linear voltage regulator at 100 krad(SiO2). Data fed into the Bayesian model is derived from literature on the components found within a linear voltage regulator. An example is presented with data pertaining to the device’s bipolar junction transistor (BJT)’s gain degradation factor (GDF). Kernel density estimation is used to provide insight into the dataset’s general distribution shape. This guides the engineer into picking the appropriate distribution for device-level Bayesian analysis. Failure probabilities generated from the Bayesian analysis are incorporated into a LTspice model to derive a system failure probability (using Monte Carlo) of the regulator’s output. In our demonstration system, a 96.5% likelihood of system degradation was found in the assumed environment
The HIPASS Catalogue - II. Completeness, Reliability, and Parameter Accuracy
The HI Parkes All Sky Survey (HIPASS) is a blind extragalactic HI 21-cm
emission line survey covering the whole southern sky from declination -90 to
+25. The HIPASS catalogue (HICAT), containing 4315 HI-selected galaxies from
the region south of declination +2, is presented in Meyer et al. (2004a, Paper
I). This paper describes in detail the completeness and reliability of HICAT,
which are calculated from the recovery rate of synthetic sources and follow-up
observations, respectively. HICAT is found to be 99 per cent complete at a peak
flux of 84 mJy and an integrated flux of 9.4 Jy km/s. The overall reliability
is 95 per cent, but rises to 99 per cent for sources with peak fluxes >58 mJy
or integrated flux > 8.2 Jy km/s. Expressions are derived for the uncertainties
on the most important HICAT parameters: peak flux, integrated flux, velocity
width, and recessional velocity. The errors on HICAT parameters are dominated
by the noise in the HIPASS data, rather than by the parametrization procedure.Comment: Accepted for publication in MNRAS. 12 pages, 11 figures. Paper with
higher resolution figures can be downloaded from http://hipass.aus-vo.or
The Northern HIPASS catalogue - Data presentation, completeness and reliability measures
The Northern HIPASS catalogue (NHICAT) is the northern extension of the
HIPASS catalogue, HICAT (Meyer et al. 2004). This extension adds the sky area
between the declination range of +2 deg < dec. < +25.5 deg to HICAT's
declination range of -90 deg < dec. < +2 deg. HIPASS is a blind HI survey using
the Parkes Radio Telescope covering 71% of the sky (including this northern
extension) and a heliocentric velocity range of -1,280 km/s to 12,700 km/s .
The entire Virgo Cluster region has been observed in the Northern HIPASS. The
galaxy catalogue, NHICAT, contains 1002 sources with v_hel > 300 km/s . Sources
with -300 km/s < v_hel < 300 km/s were excluded to avoid contamination by
Galactic emission. In total, the entire HIPASS survey has found 5317 galaxies
identified purely by their HI content. The full galaxy catalogue is
publicly-available at .Comment: 12 pages, accepted for publication by MNRA
Macronuclear Genome Sequence of the Ciliate Tetrahymena thermophila, a Model Eukaryote
The ciliate Tetrahymena thermophila is a model organism for molecular and cellular biology. Like other ciliates, this species has separate germline and soma functions that are embodied by distinct nuclei within a single cell. The germline-like micronucleus (MIC) has its genome held in reserve for sexual reproduction. The soma-like macronucleus (MAC), which possesses a genome processed from that of the MIC, is the center of gene expression and does not directly contribute DNA to sexual progeny. We report here the shotgun sequencing, assembly, and analysis of the MAC genome of T. thermophila, which is approximately 104 Mb in length and composed of approximately 225 chromosomes. Overall, the gene set is robust, with more than 27,000 predicted protein-coding genes, 15,000 of which have strong matches to genes in other organisms. The functional diversity encoded by these genes is substantial and reflects the complexity of processes required for a free-living, predatory, single-celled organism. This is highlighted by the abundance of lineage-specific duplications of genes with predicted roles in sensing and responding to environmental conditions (e.g., kinases), using diverse resources (e.g., proteases and transporters), and generating structural complexity (e.g., kinesins and dyneins). In contrast to the other lineages of alveolates (apicomplexans and dinoflagellates), no compelling evidence could be found for plastid-derived genes in the genome. UGA, the only T. thermophila stop codon, is used in some genes to encode selenocysteine, thus making this organism the first known with the potential to translate all 64 codons in nuclear genes into amino acids. We present genomic evidence supporting the hypothesis that the excision of DNA from the MIC to generate the MAC specifically targets foreign DNA as a form of genome self-defense. The combination of the genome sequence, the functional diversity encoded therein, and the presence of some pathways missing from other model organisms makes T. thermophila an ideal model for functional genomic studies to address biological, biomedical, and biotechnological questions of fundamental importance
The time scale of recombination rate evolution in great apes
We present three linkage-disequilibrium (LD)-based recombination maps generated using whole-genome sequence data from 10 Nigerian chimpanzees, 13 bonobos, and 15 western gorillas, collected as part of the Great Ape Genome Project (Prado-Martinez J, et al. 2013. Great ape genetic diversity and population history. Nature 499:471-475). We also identified species-specific recombination hotspots in each group using a modified LDhot framework, which greatly improves statistical power to detect hotspots at varying strengths. We show that fewer hotspots are shared among chimpanzee subspecies than within human populations, further narrowing the time scale of complete hotspot turnover. Further, using species-specific PRDM9 sequences to predict potential binding sites (PBS), we show higher predicted PRDM9 binding in recombination hotspots as compared to matched cold spot regions in multiple great ape species, including at least one chimpanzee subspecies. We found that correlations between broad-scale recombination rates decline more rapidly than nucleotide divergence between species. We also compared the skew of recombination rates at centromeres and telomeres between species and show a skew from chromosome means extending as far as 10-15Mb from chromosome ends. Further, we examined broad-scale recombination rate changes near a translocation in gorillas and found minimal differences as compared to other great ape species perhaps because the coordinates relative to the chromosome ends were unaffected. Finally, on the basis of multiple linear regression analysis, we found that various correlates of recombination rate persist throughout the African great apes including repeats, diversity, and divergence. Our study is the first to analyze within- And between-species genome-wide recombination rate variation in several close relatives
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