2,345 research outputs found
Advanced gearbox technology
An advanced 13,000 HP, counterrotating (CR) gearbox was designed and successfully tested to provide a technology base for future designs of geared propfan propulsion systems for both commercial and military aircraft. The advanced technology CR gearbox was designed for high efficiency, low weight, long life, and improved maintainability. The differential planetary CR gearbox features double helical gears, double row cylindrical roller bearings integral with planet gears, tapered roller prop support bearings, and a flexible ring gear and diaphragm to provide load sharing. A new Allison propfan back-to-back gearbox test facility was constructed. Extensive rotating and stationary instrumentation was used to measure temperature, strain, vibration, deflection and efficiency under representative flight operating conditions. The tests verified smooth, efficient gearbox operation. The highly-instrumented advanced CR gearbox was successfully tested to design speed and power (13,000 HP), and to a 115 percent overspeed condition. Measured CR gearbox efficiency was 99.3 percent at the design point based on heat loss to the oil. Tests demonstrated low vibration characteristics of double helical gearing, proper gear tooth load sharing, low stress levels, and the high load capacity of the prop tapered roller bearings. Applied external prop loads did not significantly affect gearbox temperature, vibration, or stress levels. Gearbox hardware was in excellent condition after the tests with no indication of distress
The Performance of the Robo-AO Laser Guide Star Adaptive Optics System at the Kitt Peak 2.1-m Telescope
Robo-AO is an autonomous laser guide star adaptive optics system recently
commissioned at the Kitt Peak 2.1-m telescope. Now operating every clear night,
Robo-AO at the 2.1-m telescope is the first dedicated adaptive optics
observatory. This paper presents the imaging performance of the adaptive optics
system in its first eighteen months of operations. For a median seeing value of
, the average Strehl ratio is 4\% in the band
and 29\% in the J band. After post-processing, the contrast ratio under
sub-arcsecond seeing for a primary star is five and
seven magnitudes at radial offsets of and
, respectively. The data processing and archiving pipelines
run automatically at the end of each night. The first stage of the processing
pipeline shifts and adds the data using techniques alternately optimized for
stars with high and low SNRs. The second "high contrast" stage of the pipeline
is eponymously well suited to finding faint stellar companions.Comment: 12 pages, 16 figures, to be submitted to PAS
Ospemifene Displays Broad-Spectrum Synergistic Interactions with Itraconazole Through Potent Interference with Fungal Efflux Activities
Azole antifungals are vital therapeutic options for treating invasive mycotic infections. However, the emergence of azole-resistant isolates combined with limited therapeutic options presents a growing challenge in medical mycology. To address this issue, we utilized microdilution checkerboard assays to evaluate nine stilbene compounds for their ability to interact synergistically with azole drugs, particularly against azole-resistant fungal isolates. Ospemifene displayed the most potent azole chemosensitizing activity, and its combination with itraconazole displayed broad-spectrum synergistic interactions against Candida albicans, Candida auris, Cryptococcus neoformans, and Aspergillus fumigatus (ΣFICI = 0.05–0.50). Additionally, in a Caenorhabditis elegans infection model, the ospemifene-itraconazole combination significantly reduced fungal CFU burdens in infected nematodes by ~75–96%. Nile Red efflux assays and RT-qPCR analysis suggest ospemifene interferes directly with fungal efflux systems, thus permitting entry of azole drugs into fungal cells. This study identifies ospemifene as a novel antifungal adjuvant that augments the antifungal activity of itraconazole against a broad range of fungal pathogens
Laser synthesis of carbon-rich SiC nanoribbons
A nanosecond pulsed laser direct-write and doping (LDWD) technique is used for the fabrication of carbon-rich silicon carbide nanoribbons, heterostructure in a single crystal 4H-SiC wafer. Characterization by high-resolution transmission electron microscope and selected area electron diffraction pattern revealed the presence of nanosize crystalline ribbons with hexagonal graphite structure in the heat-affected zone below the decomposition temperature isotherm in the SiC epilayer. The nanoribbons exist in three layers each being approximately 50-60 nm thick, containing 15-17 individual sheets. The layers are self-aligned on the (0001) plane of the SiC epilayer with their c axis at 87degrees to the incident laser beam. The LDWD technique permits synthesis of heterostructured nanoribbons in a. single step without additional material or catalyst, and effectively eliminates, the need for nanostructure handling and transferring processes
Influence of body condition on the population dynamics of Atlantic salmon with consideration of the potential impact of sea lice
We thank Marine Scotland Science (MSS) for providing the studentship for this work. We are grateful to Alexander G Murray from MSS Aberdeen for providing data for model parameterization. We also want to thank Gordon Smith and Ian Simpson from MSS Montrose, as well as the owner and staff of the net fishery at North Esk for enabling data collection. We thank Peerage of Science and two anonymous referees for constructive comments and critique points which considerably improved earlier drafts.Peer reviewedPublisher PD
Repurposing Approach IdentifiesPitavastatin as a Potent AzoleChemosensitizing Agent EffectiveAgainst Azole-Resistant CandidaSpecies
The limited number of antifungals and the rising frequency of azole-resistant Candida species are growing challenges to human medicine. Drug repurposing signifies an appealing approach to enhance the activity of current antifungal drugs. Here, we evaluated the ability of Pharmakon 1600 drug library to sensitize an azole-resistant Candida albicans to the effect of fluconazole. The primary screen revealed 44 non-antifungal hits were able to act synergistically with fluconazole against the test strain. Of note, 21 compounds, showed aptness for systemic administration and limited toxic effects, were considered as potential fluconazole adjuvants and thus were termed as “repositionable hits”. A follow-up analysis revealed pitavastatin displaying the most potent fluconazole chemosensitizing activity against the test strain (ΣFICI 0.05) and thus was further evaluated against 18 isolates of C. albicans (n = 9), C. glabrata (n = 4), and C. auris (n = 5). Pitavastatin displayed broad-spectrum synergistic interactions with both fluconazole and voriconazole against ~89% of the tested strains (ΣFICI 0.05–0.5). Additionally, the pitavastatin-fluconazole combination significantly reduced the biofilm-forming abilities of the tested Candida species by up to 73%, and successfully reduced the fungal burdens in a Caenorhabditis elegans infection model by up to 96%. This study presents pitavastatin as a potent azole chemosensitizing agent that warrant further investigation
PREDICTORS OF POSTPARTUM DEPRESSION IN DUBAI, A RAPIDLY GROWING MULTICULTURAL SOCIETY IN THE UNITED ARAB EMIRATES
Background: Postpartum depression (PPD) is a significant public health problem adversely affecting mothers, their newborns,
and other members of the family. Although PPD is common and potentially dangerous, only a minority of the cases are identified in primary health care settings during routine care, and the majority of depressed mothers in the community lies unrecognized and therefore untreated.
Subjects and methods: In this study, a total of 1500 mothers were approached randomly, 808 accepted to participate, and 504
were within the inclusion criteria (women who had a birth of a singleton full-term healthy infant, had an uncomplicated pregnancy, and were within their one week to six months postpartum). The participants completed the Edinburgh Postnatal Depression Scale.
Results: A total of 168 women had an EPDS score 10, yielding a crude prevalence rate of 33%. The prevalence of suicidal
ideation was 14 out of 504 (3%), among which 11 (79%) had EPDS score of 10. We fitted multiple linear regression models to
evaluate the predictors of variables measured on the EPDS scale. This model was statistically significant p<0.0001 in predicting the total EPDS score. Women\u27s employment status, baby\u27s birth weight, stressful life event and marital conflict were statistically significant predictors.
Conclusions: The findings of this study are anticipated to entail the government and policy makers in the region to pay more
attention to the apparently high prevalence of unrevealed PPD in the community. It is crucial to enhance screening mechanisms for early detection, providing interventions to manage symptoms, and at the same time mandating local guidelines to address the PPD pathology as a high priority for the UAE population
Coupling Classical and Quantum Variables using Continuous Quantum Measurement Theory
We propose a system of equations to describe the interaction of a
quasiclassical variable with a set of quantum variables that goes
beyond the usual mean field approximation. The idea is to regard the quantum
system as continuously and imprecisely measured by the classical system. The
effective equations of motion for the classical system therefore consist of
treating the quantum variable as a stochastic c-number \x (t) the
probability distibution for which is given by the theory of continuous quantum
measurements. The resulting theory is similar to the usual mean field equations
(in which is replaced by its quantum expectation value) but with two
differences: a noise term, and more importantly, the state of the quantum
subsystem evolves according to the stochastic non-linear Schrodinger equation
of a continuously measured system. In the case in which the quantum system
starts out in a superposition of well-separated localized states, the classical
system goes into a statistical mixture of trajectories, one trajectory for each
individual localized state.Comment: 11 pages, plain Tex (with revised settings for \vsize and \voffset to
accommodate US paper sizes
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