25,145 research outputs found
Performance of a 28-inch ramjet utilizing gaseous hydrogen at a mach number of 3.6, angles of attack up to 12 deg, and pressure altitudes up to 110,000 feet
Combustion efficiency of gaseous hydrogen fuel for ramjets at very high altitudes and high distortio
Resummed Quantum Gravity
We present the current status of the a new approach to quantum general
relativity based on the exact resummation of its perturbative series as that
series was formulated by Feynman. We show that the resummed theory is UV finite
and we present some phenomenological applications as well.Comment: 4 pages, 1 figure; presented at ICHEP0
Recommended from our members
The sensitivity of the ENSO to volcanic aerosol spatial distribution in the MPI large ensemble. In open review for ESD
Using the Max Planck Institute Grand Ensemble (MPI-GE) with 200 members for the historical simulation (1850–2005), we investigate the impact of the spatial distribution of volcanic aerosols on the ENSO response. In particular, we select 3 eruptions (El Chichón, Agung and Pinatubo) in which the aerosol is respectively confined to the Northern Hemisphere, the Southern Hemisphere or equally distributed across the equator. Our results show that the ENSO anomalies start at the end of the year of the eruption and peak the following one. Especially, we found that when the aerosol is located in the Northern Hemisphere or is symmetrically distributed, El Niño-like anomalies develop while aerosol distribution confined to the Southern Hemisphere leads to a La Niña-like anomaly. Our results strongly point to the volcanically induced displacement of the ITCZ as the main mechanism that drives the ENSO response, while suggesting that the other mechanisms (the ocean dynamical thermostat, the cooling of tropical northern Africa or of the Maritime continent) commonly invoked to explain the post-eruption ENSO response appear not to be at play in our mode
Cholesterol and coronary heart disease: screening and treatment
Coronary heart disease (CHD) is a major cause of morbidity and mortality in the United Kingdom, accounting for just under one quarter of all deaths in 1995: 27% among men and 21% among women.1 Although many CHD deaths occur among elderly people, CHD accounts for 31% of male and 13% of female deaths within the 45–64 age group
Massive Elementary Particles and Black Holes
An outstanding problem posed by Einstein's general theory of relativity to
the quantum theory of point particle fields is the fate of a massive point
particle; for, in the classical solutions of Einstein's theory, such a system
should be a black hole. We use exact results in a new approach to quantum
gravity to show that this conclusion is obviated by quantum loop effects.
Phenomenological implications are discussedComment: 11 pages; 1 figure; improved text relating to asymptotic safet
Thioxoethenylidene (CCS) as a bridging ligand
The reaction of [Mo(≡CBr)(CO)2(Tp*)] (Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) with [Fe2(μ-SLi)2(CO)6] affords, inter alia, the unsymmetrical binuclear thioxoethenylidene complex [Mo2(μ,σ(C):η2(C′S)-CCS)(CO)4(Tp*)2], which may be more directly obtained from [Mo(≡CBr)(CO)2(Tp*)] and Li2S. The reaction presumably proceeds via the intermediacy of the bis(alkylidynyl)thioether complex S{C≡Mo(CO)2(Tp*)}2, which was, however, not directly observed but explored computationally and found to lie 78.6 kJ mol–1 higher in energy than the final thioxoethenylidene product. Computational interrogation of the molecules [M2(μ-C2S)(CO)2(Tp*)2] (M = Mo, W, Re, Os) reveals three plausible coordination modes for a thioxoethenylidene bridge which involve a progressive strengthening of the C–C bond and weakening of the M–C and M–S bonds, as might be expected from simple effective atomic number considerations.This work was supported by the Australian Research Council (DP130102598 and DP110101611)
Radiative Transfer in Prestellar Cores: A Monte Carlo Approach
We use our Monte Carlo radiative transfer code to study non-embedded
prestellar cores and cores that are embedded at the centre of a molecular
cloud. Our study indicates that the temperature inside embedded cores is lower
than in isolated non-embedded cores, and generally less than 12 K, even when
the cores are surrounded by an ambient cloud of small visual extinction (Av~5).
Our study shows that the best wavelength region to observe embedded cores is
between 400 and 500 microns, where the core is quite distinct from the
background. We also predict that very sensitive observations (~1-3 MJy/sr) at
170-200 microns can be used to estimate how deeply a core is embedded in its
parent molecular cloud. Finally, we present preliminary results of asymmetric
models of non-embedded cores.Comment: 8 pages, 15 figures, to appear in the conference proceedings of "Open
Issues in Local Star Formation and Early Stellar Evolution", held in Ouro
Preto (Brazil), April 5-10, 200
Lessons in learning gain: insights from a pilot project
‘Learning gain’ has become an increasingly prominent concept in debates about the effectiveness of higher education across OECD countries. In England, interest has been heightened by the Higher Education Funding Council for England (HEFCE)’s major research initiative on learning gain, launched in 2015, and by the new Teaching Excellence Framework which assesses learning and teaching and student outcomes. HEFCE’s novel research initiative has funded a set of experimental projects across the English higher education sector for the first time. This paper presents preliminary findings from one such project at the University of East Anglia (UEA). The project trials and evaluates three approaches to identifying and measuring learning gain using data from cohorts of students across different discipline areas during 2015–2016 and 2016–2017. It builds upon previous work carried out at UEA in developing self-efficacy assessments and applying concept inventories. Student marks provide a simple comparator as a third approach to measuring learning gain
ML-SIM: universal reconstruction of structured illumination microscopy images using transfer learning.
Structured illumination microscopy (SIM) has become an important technique for optical super-resolution imaging because it allows a doubling of image resolution at speeds compatible with live-cell imaging. However, the reconstruction of SIM images is often slow, prone to artefacts, and requires multiple parameter adjustments to reflect different hardware or experimental conditions. Here, we introduce a versatile reconstruction method, ML-SIM, which makes use of transfer learning to obtain a parameter-free model that generalises beyond the task of reconstructing data recorded by a specific imaging system for a specific sample type. We demonstrate the generality of the model and the high quality of the obtained reconstructions by application of ML-SIM on raw data obtained for multiple sample types acquired on distinct SIM microscopes. ML-SIM is an end-to-end deep residual neural network that is trained on an auxiliary domain consisting of simulated images, but is transferable to the target task of reconstructing experimental SIM images. By generating the training data to reflect challenging imaging conditions encountered in real systems, ML-SIM becomes robust to noise and irregularities in the illumination patterns of the raw SIM input frames. Since ML-SIM does not require the acquisition of experimental training data, the method can be efficiently adapted to any specific experimental SIM implementation. We compare the reconstruction quality enabled by ML-SIM with current state-of-the-art SIM reconstruction methods and demonstrate advantages in terms of generality and robustness to noise for both simulated and experimental inputs, thus making ML-SIM a useful alternative to traditional methods for challenging imaging conditions. Additionally, reconstruction of a SIM stack is accomplished in less than 200 ms on a modern graphics processing unit, enabling future applications for real-time imaging. Source code and ready-to-use software for the method are available at http://ML-SIM.github.io
- …