6,855 research outputs found
DC-10 composite vertical stabilizer ground test program
A review of the structural configuration and ground test program is presented. Particular emphasis is placed on the testing of a full-scale stub box test subcomponent and full span ground test unit. The stub box subcomponent was tested in an environmental chamber under ambient, cold/wet, and hot/wet conditions. The test program included design limit static loads, fatigue spectrum loading to approximately two service lifetimes (with and without damage), design limit damage tolerance tests, and a final residual strength test to a structural failure. The first full-scale ground test unit was tested under ambient conditions. The test unit was to have undergone static, fatigue, and damage tolerance tests but a premature structural failure occurred at design limit load during the third limit load test. A failure theory was developed which explains the similarity in types of failure and the large load discrepancy at failure between the two test articles. The theory attributes both failures to high stress concentrations at the edge of the lower rear spar access opening. A second full-scale ground test unit has been modified to incorporate the various changes resulting from the premature failure. The article has been assembled and is active in the test program
The baboon endogenous virus genome. II. Provirus sequence variations in baboon cell DNA
Restriction analysis of the approximately 100 integrated baboon endogenous virus (BaEV) proviruses in baboon cells and tissues has revealed two major sequence variations, both in the gag gene region of the genome. One, a 150 nucleotide pair insert, is present in a small proportion of the proviral DNAs of some baboons, but is present in the majority of the proviral DNAs of other baboons. The second, a Bam HI recognition sequence located 2.25 kb from the proviral 5' end, is missing or modified in approximately one-half of the integrated genomes. We consider the possibility that accumulation of proviruses not containing the 0.15 kb insert is correlated with viral activation and expression since it is this form that is a replication intermediate in freshly infected permissive cells. It is evident from these initial studies that the organization of the multiple BaEV proviruses in baboon DNA has undergone modification during evolution
A New Colorimetric Assay of Apurinic/Apyrimidinic (Abasic) Sites of Deoxyribonucleic acid (DNA) Using Bicinchoninic Acid [
Apurinic/apyrimidinic (AP or abasic) sites are DNA lesions that result from the loss of a nucleobase by hydrolysis of the N-glycosyl bond. It is estimated that AP sites are the most frequent lesions in cells with about 10,000-50,000 times per day per cell under typical aerobic conditions [2]. The formation of AP sites is caused by environmental and cancer therapeutic genotoxins such as alkylating agents, oxidizing agents, ionizing radiation, and ultraviolet radiation.https://scholarworks.moreheadstate.edu/celebration_posters_2022/1024/thumbnail.jp
Tuberculosis, human rights, and law reform: Addressing the lack of progress in the global tuberculosis response
In 2018, the United Nations General Assembly convened the first-ever high-level meeting (HLM) on tuberculosis (TB). Since that time news on the world’s most lethal infectious disease is not good—the 2019 WHO TB report shows 1.2 million people died from TB, a number that has fallen just 11% since 2015, less than one-third of the way towards the End TB Strategy milestone of a 35% reduction (to about 850 million deaths) by 2020. The same number of people, 10.0 million, are estimated to have fallen ill with TB in 2018 as in 2017. The stubborn persistence of TB is attributable to glaring gaps in case detection and treatment. While case detection has increased in recent years, there is still a significant gap between the 7 million new cases reported and the 10 million incident cases estimated in the most recent WHO data—and treatment success continues to hover at only 85%.
There has long been a call for a shift toward a “human rights-based approach” in TB—building policies and programs explicitly on the norms and values set out in international human rights law, treating people with TB as rights holders in their interaction with the state and the health system, and working to overcome stigma and discrimination. Yet laws in high TB-burden countries (HBCs) have not been reformed to include basic rights protections. This helps explain the lack of progress, as individuals who fear discrimination and coercion may avoid diagnosis and treatment. Thus, TB stands in stark contrast to HIV/AIDS, for which the international community has moved far more decisively to recognize and protect key rights, even as more progress is needed. At the UN, heads of state committed to removing discriminatory laws and policies against people with TB, protecting and promoting their human rights and dignity, as a key part of a strategy to improve the TB response and end the epidemic. Here, we analyze key areas of law with particular importance for TB, focusing on five aspects of compulsory public health powers in law and on laws related to migration. We identify significant gaps between core human rights norms and existing legal environments
Accuracy threshold for concatenated error detection in one dimension
Estimates of the quantum accuracy threshold often tacitly assume that it is
possible to interact arbitrary pairs of qubits in a quantum computer with a
failure rate that is independent of the distance between them. None of the many
physical systems that are candidates for quantum computing possess this
property. Here we study the performance of a concatenated error-detection code
in a system that permits only nearest-neighbor interactions in one dimension.
We make use of a new message-passing scheme that maximizes the number of errors
that can be reliably corrected by the code. Our numerical results indicate that
arbitrarily accurate universal quantum computation is possible if the
probability of failure of each elementary physical operation is below
approximately 10^{-5}. This threshold is three orders of magnitude lower than
the highest known.Comment: 7 pages, 4 figures, now with error bar
Baboon endogenous virus genome: Molecular cloning and structural characterization of nondefective viral genomes from DNA of a baboon cell strain
Several heterogeneities in the baboon endogenous virus (BaEV) genomes that are present in the DNA of normal baboon tissues and the baboon cell strain BEF-3 have been described previously. To study these genomes, we cloned BaEV proviruses from BEF-3 cellular DNA into the vector Charon 4A. Of the four full-length clones isolated, one was nondefective as determined by transfection. The sequence of a portion of this clone was found to code for amino acids 61-91 in the p30 region of the gag gene. This identification allowed us to align the restriction map with the BaEV genetic map. One heterogeneity, a BamHI site 2.4 kilobases (kb) from the proviral 5' end, was located close to the gag-pol junction; another, a BamHI site 1.4 kb from the 5' end of the genome, corresponded to the gag p30 coding sequence for amino acids 32-34; and a third, a Xho I site, was near the 3' end of the pol gene. To select the nondefective BaEV genomes from BEF-3 cells, we infected permissive cells with virus produced by BEF-3 cells and also transfected BEF-3 cellular DNA into permissive cells. The BaEV genomes in the permissive recipient cultures were then analyzed by restriction enzyme analysis. These nondefective genomes were found to be heterogeneous with respect to the gag-pol BamHI site and the Xho I site, but all were found to contain the BamHI site 1.4 kb from the 5' end of the genome
Dextran Sulfate Sodium Inhibits Alanine Synthesis in Caco-2 Cells
To understand and characterize the pathogenic mechanisms of inflammatory bowel disease, dextran sulfate sodium (DSS) has been used to induce acute and chronic colitis in animal models by causing intestinal epithelium damage. The mechanism of action of DSS in producing this outcome is not well understood. In an effort to understand how DSS might impact epithelial cell metabolism, we studied the intestinal epithelial cell line Caco-2 incubated with 1% DSS over 56 hours using 1H NMR spectroscopy. We observed no difference in cell viability as compared to control cultures, and an approximately 1.5-fold increase in IL-6 production upon incubation with 1% DSS. The effect on Caco-2 cell metabolism as measured through changes in the concentration of metabolites in the cell supernatant included a three-fold decrease in the concentration of alanine. Given that the concentrations of other amino acids in the cell culture supernatant were not different between treated and control cultures over 56 hours suggest that DSS inhibits alanine synthesis, specifically alanine aminotransferase, without affecting other key metabolic pathways. The importance of alanine aminotransferase in inflammatory bowel disease is discussed
Three-dimensional electronic instabilities in polymerized solid A1C60
The low-temperature structure of A1C60 (A=K, Rb) is an ordered array of
polymerized C60 chains, with magnetic properties that suggest a non-metallic
ground state. We study the paramagnetic state of this phase using
first-principles electronic-structure methods, and examine the magnetic
fluctuations around this state using a model Hamiltonian. The electronic and
magnetic properties of even this polymerized phase remain strongly three
dimensional, and the magnetic fluctuations favor an unusual three-dimensional
antiferromagnetically ordered structure with a semi-metallic electronic
spectrum.Comment: REVTeX 3.0, 10 pages, 4 figures available on request from
[email protected]
Metal-insulator transitions: Influence of lattice structure, Jahn-Teller effect, and Hund's rule coupling
We study the influence of the lattice structure, the Jahn-Teller effect and
the Hund's rule coupling on a metal-insulator transition in AnC60 (A= K, Rb).
The difference in lattice structure favors A3C60 (fcc) being a metal and A4C60
(bct) being an insulator, and the coupling to Hg Jahn-Teller phonons favors
A4C60 being nonmagnetic. The coupling to Hg (Ag) phonons decreases (increases)
the value Uc of the Coulomb integral at which the metal-insulator transition
occurs. There is an important partial cancellation between the Jahn-Teller
effect and the Hund's rule coupling.Comment: 4 pages, RevTeX, 3 eps figure, additional material available at
http://www.mpi-stuttgart.mpg.de/docs/ANDERSEN/fullerene
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