5,280 research outputs found
Man-computer role in space navigation and guidance Final report
Man computer roles and hardware requirements for navigation and guidance in deep space manned mission
Man-computer roles in space navigation and guidance, phase I
Estimated man-machine requirement computations for space navigation and guidanc
Genetic Dissection of a QTL Affecting Bone Geometry.
Parameters of bone geometry such as width, length, and cross-sectional area are major determinants of bone strength. Although these traits are highly heritable, few genes influencing bone geometry have been identified. Here, we dissect a major quantitative trait locus (QTL) influencing femur size. This QTL was originally identified in an F2 cross between the C57BL/6J-hg/hg (HG) and CAST/EiJ strains and was referred to as femur length in high growth mice 2 (Feml2). Feml2 was located on chromosome (Chr.) 9 at ∼20 cM. Here, we show that the HG.CAST-(D9Mit249-D9Mit133)/Ucd congenic strain captures Feml2 In an F2 congenic cross, we fine-mapped the location of Feml2 to an ∼6 Mbp region extending from 57.3 to 63.3 Mbp on Chr. 9. We have identified candidates by mining the complete genome sequence of CAST/EiJ and through allele-specific expression (ASE) analysis of growth plates in C57BL/6J × CAST/EiJ F1 hybrids. Interestingly, we also find that the refined location of Feml2 overlaps a cluster of six independent genome-wide associations for human height. This work provides the foundation for the identification of novel genes affecting bone geometry
Mechanisms of cell injury by activated oxygen species.
Current evidence suggests that O2- and H2O2 injure cells as a result of the generation of a more potent oxidizing species. In addition to O2- and H2O2, the third essential component of the complex that mediates the lethal cell injury is a cellular source of ferric iron. The hypothesis most consistent with all the available data suggests that O2- reduces a cellular source of ferric to ferrous iron, and the latter then reacts with H2O2 to produce a more potent oxidizing species, like the .OH or an equivalently reactive species. In turn, .OH initiates the peroxidative decomposition of the phospholipids of cellular membranes. .OH also damages the inner mitochondrial membrane. Upon mitochondrial deenergization, a sequence of events is initiated that similarly leads to the loss of viability of the cell. DNA represents a third cellular target of .OH. Depending on the cell type, oxidative DNA damage can be coupled to cell killing through a mechanism related to the activation of poly (ADP-ribose) polymerase
Periodic Evaluation of Northeastern Spruce and Balsam Fir Lumber Properties
PERIODIC EVALUATION OF NORTHEASTERN SPRUCE AND BALSAM FIR LUMBER PROPERTIES
By Benjamin Farber
Advisors: Dr. Douglas Gardner
An Abstract of the Thesis Presented
In Partial Fulfilment of the Requirements for the
Degree of Master of Science
(In Forest Resources)
August 2018
In the past two decades, proportions of juvenile wood have increased in lumber cut from intensively managed Southern yellow pine (Pinus spp.) plantation-based forests. Knowing that a decrease in rotation age can increase proportions of juvenile wood, which in turn negatively affects mechanical properties in lumber, the SYP grouping was evaluated to determine if the published design values in the National Design Specification (NDS) required a downward adjustment. In 2011, following extensive testing, the American Lumber Standards Committee (ALSC) required that design values for SYP be reduced by 30 percent. As a result of this, ASTM D1990-16 was revised to include required periodic monitoring of all lumber species groupings to detect possible downward shifts in mechanical properties. The Northeastern Lumber Manufacturing Association (NELMA) conducts monitoring programs approximately every five years within the Northeast and Great Lakes regions, two of the three regions where SPF(s) lumber is produced (the third region is in the Western U.S. which is monitored by the Western Wood Products Association (WWPA)). The monitoring program described herein, as required by ASTM D1990-16, evaluates bending properties of balsam fir (Abies balsamea) and the Eastern spruces (Picea rubens, Picea glauca, Picea mariana and Picea abies) for No.2 grade 2” x 4” lumber. In addition to the required 2” x 4” size this research program also evaluated 2” x 6” and 2” x 8”.
The monitoring program requires testing and subsequent analysis follows ASTM standards D1990-16 and D4761-13, the latter specifying testing procedures for static bending tests of lumber.
After lumber flexural failure, procedures outlined in ASTM D4761-13 were applied to each specimen to diagram and quantify the failure behavior and create a failure code. This failure code is used in the determination of the strength ratio which is then used to calculate Grade Quality Index (GQI), which is used to determine if further lumber mechanical property adjustments are required.
The 2” x 4” modulus of rupture (MOR) and modulus of elasticity (MOE) values derived from this testing program were statistically compared to the three separate testing programs. The 2” x 6” and 2” x 8” values from the 2017 monitoring program, were compared with the 1991 values and showed a decrease in MOR and MOE. Further testing of the 2” x 6” and 2” x 8” No. 2 nominal widths should be conducted in future testing programs to investigate any possible downward shift in mechanical property values.
A Wilcoxon test showed that the 2” x 4” samples of both species had similar MOE values when compared with the 1991 design values, but did show a downward shift in values when comparing the MOR values. A Tukey HSD reported similar results reporting the MOE as statistically the same as the 1991 values for both species, whereas the mean MOR was statistically lower. These findings are still considered preliminary as this programs results will be pooled together with the two future monitoring programs and combined with the remaining species within SPF(s). After final submission to the ALSC, The SPF(s) pooled values will be re-evaluated
Random simplicial complexes in the medial regime
We describe topology of random simplicial complexes in the lower and upper
models in the medial regime, i.e. under the assumption that the probability
parameters approach neither nor . We show that nontrivial
Betti numbers of typical lower and upper random simplicial complexes in the
medial regime lie in a narrow range of dimensions. For instance, an upper
random simplicial complex on vertices in the medial regime with high
probability has non-vanishing Betti numbers only for where and are constants. A lower
random simplicial complex on vertices in the medial regime is with high
probability -connected and its dimension satisfies where are constants. The paper develops a new technique,
based on Alexander duality, which relates the lower and upper models.Comment: 23 pages. v2 contains an updated abstrac
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