3,128 research outputs found
Metallic threaded composite fastener
A metallic threaded composite fastener, particularly suited for high temperature applications, has a body member made of high temperature resistant composite material with a ceramic coating. The body member has a head portion configured to be installed in a countersunk hole and a shank portion which is noncircular and tapered. One part of the shank may be noncircular and the other part tapered, or the two types of surface could be combined into a frustum of a noncircular cone. A split collar member made of high strength, high temperature tolerant metal alloy is split into two halves and the interior of the halves are configured to engage the shank. The exterior of the collar has a circumferential groove which receives a lock ring to secure the collar halves to the shank. In the assembled condition torque may be transmitted from the body to the split collar by the engaged noncircular portions to install and remove the fastener assembly into or from a threaded aperture and shear loads in the collar threads are transferred to the shank tapered portion as a combination of radial compression and axial tension loads. Thus, tension loads may be applied to the fastener shank without damaging the ceramic coating
Modelling DNA Origami Self-Assembly at the Domain Level
We present a modelling framework, and basic model parameterization, for the
study of DNA origami folding at the level of DNA domains. Our approach is
explicitly kinetic and does not assume a specific folding pathway. The binding
of each staple is associated with a free-energy change that depends on staple
sequence, the possibility of coaxial stacking with neighbouring domains, and
the entropic cost of constraining the scaffold by inserting staple crossovers.
A rigorous thermodynamic model is difficult to implement as a result of the
complex, multiply connected geometry of the scaffold: we present a solution to
this problem for planar origami. Coaxial stacking and entropic terms,
particularly when loop closure exponents are taken to be larger than those for
ideal chains, introduce interactions between staples. These cooperative
interactions lead to the prediction of sharp assembly transitions with notable
hysteresis that are consistent with experimental observations. We show that the
model reproduces the experimentally observed consequences of reducing staple
concentration, accelerated cooling and absent staples. We also present a
simpler methodology that gives consistent results and can be used to study a
wider range of systems including non-planar origami
Hyperfine structure in the red emission system of NbN
A detailed study of hyperfine structure observed in the 0,0 band of the 3Φ (aβ) →3Δ (aβ) system of NbN has shown that the secondary hyperfine effects observed in this structure are not due to a perturbation in the 3Δ state but rather to the presence of a nonnegligible hyperfine effect in the 3Φ excited state. Calculations of the intensity factors corresponding to the observed transitions confirm this hypothesis and give results in excellent agreement with experiment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69362/2/JCPSA6-63-7-2861-1.pd
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Isoprenoids determine Th1/Th2 fate in pathogenic T cells, providing a mechanism of modulation of autoimmunity by atorvastatin.
3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase is a critical enzyme in the mevalonate pathway that regulates the biosynthesis of cholesterol as well as isoprenoids that mediate the membrane association of certain GTPases. Blockade of this enzyme by atorvastatin (AT) inhibits the destructive proinflammatory T helper cell (Th)1 response during experimental autoimmune encephalomyelitis and may be beneficial in the treatment of multiple sclerosis and other Th1-mediated autoimmune diseases. Here we present evidence linking specific isoprenoid intermediates of the mevalonate pathway to signaling pathways that regulate T cell autoimmunity. We demonstrate that the isoprenoid geranylgeranyl-pyrophosphate (GGPP) mediates proliferation, whereas both GGPP and its precursor, farnesyl-PP, regulate the Th1 differentiation of myelin-reactive T cells. Depletion of these isoprenoid intermediates in vivo via oral AT administration hindered these T cell responses by decreasing geranylgeranylated RhoA and farnesylated Ras at the plasma membrane. This was associated with reduced extracellular signal-regulated kinase (ERK) and p38 phosphorylation and DNA binding of their cotarget c-fos in response to T cell receptor activation. Inhibition of ERK and p38 mimicked the effects of AT and induced a Th2 cytokine shift. Thus, by connecting isoprenoid availability to regulation of Th1/Th2 fate, we have elucidated a mechanism by which AT may suppress Th1-mediated central nervous system autoimmune disease
Neuronal activation for semantically reversible sentences
Semantically reversible sentences are prone to misinterpretation and take longer for typically developing children and adults to comprehend; they are also particularly problematic for those with language difficulties such as aphasia or Specific Language Impairment. In our study, we used fMRI to compare the processing of semantically reversible and nonreversible sentences in 41 healthy participants to identify how semantic reversibility influences neuronal activation. By including several linguistic and nonlinguistic conditions within our paradigm, we were also able to test whether the processing of semantically reversible sentences places additional load on sentence-specific processing, such as syntactic processing and syntactic-semantic integration, or on phonological working memory. Our results identified increased activation for reversible sentences in a region on the left temporal–parietal boundary, which was also activated when the same group of participants carried out an articulation task which involved saying “one, three” repeatedly. We conclude that the processing of semantically reversible sentences places additional demands on the subarticulation component of phonological working memory
A comparison of the growth of the C4 grass Spartina anglica with the C3 grass Lolium perenne at different temperatures.
The Southern Flying Squirrel (\u3ci\u3eGlaucomys volans\u3c/i\u3e) in Lincoln, Nebraska
The southern flying squirrel (Glaucomys volans) is considered a species of greatest conservation need in Nebraska and listed as threatened in the state. Historically, the geographic range of the southern flying squirrel in Nebraska has been restricted to five eastern counties from a northern suburb of Omaha, Douglas Co., southward in the four counties of Sarpy, Otoe, Nemaha, and Richardson, all bordering the Missouri River on the east. In late November of 2018, a resident of Lincoln, Lancaster Co., Nebraska, contacted the Nebraska Game and Parks Commission about an animal found dead in his yard. This animal proved to be a southern flying squirrel, which was 50 [80 km] to 70 [112 km] miles west of the known geographic range of the species. Two additional individuals were subsequently observed at the original residence as were individuals in at least eight separate neighborhoods throughout the city of Lincoln. Clearly, a population of the southern flying squirrels is established and reproducing in Lincoln, but their origin is unknown. The source of this city-dwelling population may be from released/escaped pets, a natural dispersal from the Missouri River via the Platte River and Salt Creek, or inadvertent translocation when moving timber or fire wood
A genomic analysis and transcriptomic atlas of gene expression in Psoroptes ovis reveals feeding- and stage-specific patterns of allergen expression
Background: Psoroptic mange, caused by infestation with the ectoparasitic mite, Psoroptes ovis, is highly contagious, resulting in intense pruritus and represents a major welfare and economic concern for the livestock industry Worldwide. Control relies on injectable endectocides and organophosphate dips, but concerns over residues, environmental contamination, and the development of resistance threaten the sustainability of this approach, highlighting interest in alternative control methods. However, development of vaccines and identification of chemotherapeutic targets is hampered by the lack of P. ovis transcriptomic and genomic resources.
Results: Building on the recent publication of the P. ovis draft genome, here we present a genomic analysis and transcriptomic atlas of gene expression in P. ovis revealing feeding- and stage-specific patterns of gene expression, including novel multigene families and allergens. Network-based clustering revealed 14 gene clusters demonstrating either single- or multi-stage specific gene expression patterns, with 3075 female-specific, 890 male-specific and 112, 217 and 526 transcripts showing larval, protonymph and tritonymph specific-expression, respectively. Detailed analysis of P. ovis allergens revealed stage-specific patterns of allergen gene expression, many of which were also enriched in "fed" mites and tritonymphs, highlighting an important feeding-related allergenicity in this developmental stage. Pair-wise analysis of differential expression between life-cycle stages identified patterns of sex-biased gene expression and also identified novel P. ovis multigene families including known allergens and novel genes with high levels of stage-specific expression.
Conclusions: The genomic and transcriptomic atlas described here represents a unique resource for the acarid-research community, whilst the OrcAE platform makes this freely available, facilitating further community-led curation of the draft P. ovis genome
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