304 research outputs found
Detecting Flaws in the Presence of Strong Geometry Signals in F100 Gas Turbine Engine Components
The inspection of F-100 gas turbine engine components using the Retirement For Cause (RFC) Eddy Current Inspection Station includes the requirement to scan three common but critical geometries: Antirotation windows (ARW), antirotation tangs (ART) and the live rim (LR) area at the component rim, as shown in Figures 1 and 2. These geometries have a common feature — edges, as shown in Figure 3 — that presents a challenge to successful inspection. The edges are sources of strong geometry signals that often have a higher amplitude than flaw signals, thus making a conventional amplitude inspection technique difficult. Therefore, a “frequency select” technique was developed which uses the frequency difference as a flaw determination criteria [1,2]. Using this technique, the RFC System has successfully detected both EDM notches and fatigue cracks in these geometries located in engine components fabricated of IN-100, waspaloy and titanium
Automated Eddy Current Detection of Edge Defects in a Complex Geometry Using a Magnitude Approach
The inspection capability on turbine engine disks is important to the safety of an airplane. Eddy current inspection has been widely accepted as an effective tool in detecting small fatigue cracks on engine disks. The inspection of simple geometries such as boltholes, webs and bores in a engine disk is less complicated than those of complex geometries such as antirotation windows, scallops, dovetails and non-circular holes. One of the main difficulties in inspecting complex geometries is due to the presence of irregular edges. Raatz [1] reported the influence of edges in measuring conductivity. Williams, Tilson and Blitz [2] minimized the change of phase angle variation around an edge by the proper selection of inspection frequency and coil size. Elsberry and Bailey [3] enhanced edge defect detection by using a shielded probe to collimate the field. Hoppe and Stubbs [4], on the other hand, used the frequency content of the edge signals to discern the edge defect in antirotation windows. This frequency approach was extended to the inspection of other complex geometries such as antirotation tangs and live rims by Ko [5]. Furthermore, Ko [6] used the edge signals in scallops to position a rotational probe in a scallop prior to inspection. These techniques [4–6] are limited to partial inspection of the geometries; however, a new technique is needed if an entire inspection of a complex geometry is required. This paper discusses the use of a simple mechanical mechanism to adapt to a complex geometry, and a signal processing technique for the detection of edge defects.</p
Trends in mortality from Hodgkin's disease in western and eastern Europe
Hodgkin's disease mortality rates steadily declined by about 75% between the late 1960's and the late 1990's in the current European Union countries and the USA, and Japan. Eastern European countries, however, showed only an approximately 40% decline between the late 1960's and the early 1990's, and no further fall thereafter
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Results of the MAJORANA DEMONSTRATOR's Search for Double-Beta Decay of 76Ge to Excited States of 76Se
The MAJORANA DEMONSTRATOR is searching for double-beta decay of 76Ge to excited states (E.S.) in 76Se using a modular array of high purity Germanium detectors. 76Ge can decay into three E.S.s of 76Se. The E.S. decays have a clear event signature consisting of a ββ-decay with the prompt emission of one or two γ-rays, resulting in with high probability in a multi-site event. The granularity of the DEMONSTRATOR detector array enables powerful discrimination of this event signature from backgrounds. Using 21.3 kg-y of isotopic exposure, the DEMONSTRATOR has set world leading limits for each E.S. decay, with 90% CL lower half-life limits in the range of (0.56 2.1) ⋅ 1024 y. In particular, for the 2v transition to the first 0+ E.S. of 76Se, a lower half-life limit of 0.68 ⋅ 1024 at 90% CL was achieved
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ADC Nonlinearity Correction for the Majorana Demonstrator
Imperfections in analog-to-digital conversion (ADC) cannot be ignored when signal digitization requirements demand both wide dynamic range and high resolution, as is the case for the Majorana Demonstrator 76Ge neutrinoless double-beta decay search. Enabling the experiment's high-resolution spectral analysis and efficient pulse shape discrimination required careful measurement and correction of ADC nonlinearities. A simple measurement protocol was developed that did not require sophisticated equipment or lengthy data-taking campaigns. A slope-dependent hysteresis was observed and characterized. A correction applied to digitized waveforms prior to signal processing reduced the differential and integral nonlinearities by an order of magnitude, eliminating these as dominant contributions to the systematic energy uncertainty at the double-beta decay Q value
The role of multiple marks in epigenetic silencing and the emergence of a stable bivalent chromatin state
We introduce and analyze a minimal model of epigenetic silencing in budding
yeast, built upon known biomolecular interactions in the system. Doing so, we
identify the epigenetic marks essential for the bistability of epigenetic
states. The model explicitly incorporates two key chromatin marks, namely H4K16
acetylation and H3K79 methylation, and explores whether the presence of
multiple marks lead to a qualitatively different systems behavior. We find that
having both modifications is important for the robustness of epigenetic
silencing. Besides the silenced and transcriptionally active fate of chromatin,
our model leads to a novel state with bivalent (i.e., both active and
silencing) marks under certain perturbations (knock-out mutations, inhibition
or enhancement of enzymatic activity). The bivalent state appears under several
perturbations and is shown to result in patchy silencing. We also show that the
titration effect, owing to a limited supply of silencing proteins, can result
in counter-intuitive responses. The design principles of the silencing system
is systematically investigated and disparate experimental observations are
assessed within a single theoretical framework. Specifically, we discuss the
behavior of Sir protein recruitment, spreading and stability of silenced
regions in commonly-studied mutants (e.g., sas2, dot1) illuminating the
controversial role of Dot1 in the systems biology of yeast silencing.Comment: Supplementary Material, 14 page
Family history of cancer as a risk factor for second malignancies after Hodgkin's lymphoma
This study estimated the risk of second primary malignancies after Hodgkin's lymphoma (HL) in relation to family history of cancer, age at diagnosis and latency, among 6946 patients treated for HL in Sweden in 1965–1995 identified through the Swedish Cancer Register (SCR). First-degree relatives (FDRs) to the HL patients and their malignancies were then ascertained together with their malignancies through the Multi-Generation Registry and SCR. The HL patient cohort was stratified on the number of FDRs with cancer, and standardised incidence ratios (SIRs) of developing SM were analysed. In the HL cohort, 781 SM were observed 1 year or longer after HL diagnosis. The risk for developing SM increased with the number of FDRs with cancer, SIRs being 2.26, 3.01, and 3.45 with 0, 1, or ⩾2 FDRs with cancer, respectively. Hodgkin's lymphoma long-term survivors treated at a young age with a family history of cancer carry an increased risk for developing SM and may represent a subgroup where standardised screening for the most common cancer sites could be offered in a stringent surveillance programme
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Exotic Dark Matter Search with the Majorana Demonstrator
With excellent energy resolution and ultralow-level radiogenic backgrounds, the high-purity germanium detectors in the Majorana Demonstrator enable searches for several classes of exotic dark matter (DM) models. In this work, we report new experimental limits on keV-scale sterile neutrino DM via the transition magnetic moment from conversion to active neutrinos ν_{s}→ν_{a}. We report new limits on fermionic dark matter absorption (χ+A→ν+A) and sub-GeV DM-nucleus 3→2 scattering (χ+χ+A→ϕ+A), and new exclusion limits for bosonic dark matter (axionlike particles and dark photons). These searches utilize the (1-100)-keV low-energy region of a 37.5-kg y exposure collected by the Demonstrator between May 2016 and November 2019 using a set of ^{76}Ge-enriched detectors whose surface exposure time was carefully controlled, resulting in extremely low levels of cosmogenic activation
Interaction of the Deubiquitinating Enzyme Ubp2 and the E3 Ligase Rsp5 Is Required for Transporter/Receptor Sorting in the Multivesicular Body Pathway
Protein ubiquitination is essential for many events linked to intracellular protein trafficking. We sought to elucidate the possible involvement of the S. cerevisiae deubiquitinating enzyme Ubp2 in transporter and receptor trafficking after we (this study) and others established that affinity purified Ubp2 interacts stably with the E3 ubiquitin ligase Rsp5 and the (ubiquitin associated) UBA domain containing protein Rup1. UBP2 interacts genetically with RSP5, while Rup1 facilitates the tethering of Ubp2 to Rsp5 via a PPPSY motif. Using the uracil permease Fur4 as a model reporter system, we establish a role for Ubp2 in membrane protein turnover. Similar to hypomorphic rsp5 alleles, cells deleted for UBP2 exhibited a temporal stabilization of Fur4 at the plasma membrane, indicative of perturbed protein trafficking. This defect was ubiquitin dependent, as a Fur4 N-terminal ubiquitin fusion construct bypassed the block and restored sorting in the mutant. Moreover, the defect was absent in conditions where recycling was absent, implicating Ubp2 in sorting at the multivesicular body. Taken together, our data suggest a previously overlooked role for Ubp2 as a positive regulator of Rsp5-mediated membrane protein trafficking subsequent to endocytosis
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