Perturbation Approach to the Self Energy of non-S Hydrogenic States

We present results on the self-energy correction to the energy levels of hydrogen and hydrogenlike ions. The self energy represents the largest QED correction to the relativistic (Dirac-Coulomb) energy of a bound electron. We focus on the perturbation expansion of the self energy of non-S states, and provide estimates of the so-called A60 perturbative coefficient, which can be considered as a relativistic Bethe logarithm. Precise values of A60 are given for many P, D, F and G states, while estimates are given for other electronic states. These results can be used in high-precision spectroscopy experiments in hydrogen and hydrogenlike ions. They yield the best available estimate of the self-energy correction of many atomic states.Comment: 18 pages (in 2-column format), 21 figures. Version 2 (June 20, 2003) includes minor modification

Detection and optimization of suspension-free logic programs

AbstractIn recent years, language mechanisms to suspend, or delay, the execution of goals until certain variables become bound have become increasingly popular in logic programming languages. While convenient, such mechanisms can make control flow within a program difficult to predict at compile time, and therefore render many traditional compiler optimizations inapplicable. Unfortunately, this performance cost is also incurred by programs that do not use any delay primitives. In this paper, we describe a simple dataflow analysis for detecting computations where suspension effects can be ignored, and discuss several low-level optimizations that rely on this information. Our algorithm has been implemented in the jc system. Optimizations based on information it produces result in significant performance improvements, demonstrating speed comparable to or exceeding that of optimized C programs

Femtosecond Spectrotemporal Magneto-Optics

A new method to measure and analyze the time and spectrally resolved polarimetric response of magnetic materials is presented. It allows us to study the ultrafast magnetization dynamics of a CoPt3 ferromagnetic film. The analysis of the pump-induced rotation and ellipticity detected by a broad spectrum probe beam shows that magneto-optical signals predominantly reflect the spin dynamics in ferromagnets

HI intensity mapping with FAST

We discuss the detectability of large-scale HI intensity fluctuations using the FAST telescope. We present forecasts for the accuracy of measuring the Baryonic Acoustic Oscillations and constraining the properties of dark energy. The FAST $19$-beam L-band receivers ($1.05$--$1.45$ GHz) can provide constraints on the matter power spectrum and dark energy equation of state parameters ($w_{0},w_{a}$) that are comparable to the BINGO and CHIME experiments. For one year of integration time we find that the optimal survey area is $6000\,{\rm deg}^2$. However, observing with larger frequency coverage at higher redshift ($0.95$--$1.35$ GHz) improves the projected errorbars on the HI power spectrum by more than $2~\sigma$ confidence level. The combined constraints from FAST, CHIME, BINGO and Planck CMB observations can provide reliable, stringent constraints on the dark energy equation of state.Comment: 7 pages, 3 figures, submitted to "Frontiers in Radio Astronomy and FAST Early Sciences Symposium 2015" conference proceedin

Precise calculation of transition frequencies of hydrogen and deuterium based on a least-squares analysis

We combine a limited number of accurately measured transition frequencies in hydrogen and deuterium, recent quantum electrodynamics (QED) calculations, and, as an essential additional ingredient, a generalized least-squares analysis, to obtain precise and optimal predictions for hydrogen and deuterium transition frequencies. Some of the predicted transition frequencies have relative uncertainties more than an order of magnitude smaller than that of the g-factor of the electron, which was previously the most accurate prediction of QED.Comment: 4 pages, RevTe

Relativistic and Radiative Energy Shifts for Rydberg States

We investigate relativistic and quantum electrodynamic effects for highly-excited bound states in hydrogenlike systems (Rydberg states). In particular, hydrogenic one-loop Bethe logarithms are calculated for all circular states (l = n-1) in the range 20 <= n <= 60 and successfully compared to an existing asymptotic expansion for large principal quantum number n. We provide accurate expansions of the Bethe logarithm for large values of n, for S, P and circular Rydberg states. These three expansions are expected to give any Bethe logarithms for principal quantum number n > 20 to an accuracy of five to seven decimal digits, within the specified manifolds of atomic states. Within the numerical accuracy, the results constitute unified, general formulas for quantum electrodynamic corrections whose validity is not restricted to a single atomic state. The results are relevant for accurate predictions of radiative shifts of Rydberg states and for the description of the recently investigated laser-dressed Lamb shift, which is observable in a strong coherent-wave light field.Comment: 8 pages; RevTeX

Deep learning prediction of non-perfused volume without contrast agents during prostate ablation therapy

The non-perfused volume (NPV) is an important indicator of treatment success immediately after prostate ablation. However, visualization of the NPV first requires an injection of MRI contrast agents into the bloodstream, which has many downsides. Purpose of this study was to develop a deep learning model capable of predicting the NPV immediately after prostate ablation therapy without the need for MRI contrast agents. A modified 2D deep learning UNet model was developed to predict the post-treatment NPV. MRI imaging data from 95 patients who had previously undergone prostate ablation therapy for treatment of localized prostate cancer were used to train, validate, and test the model. Model inputs were T1/T2-weighted and thermometry MRI images, which were always acquired without any MRI contrast agents and prior to the final NPV image on treatment-day. Model output was the predicted NPV. Model accuracy was assessed using the Dice-Similarity Coefficient (DSC) by comparing the predicted to ground truth NPV. A radiologist also performed a qualitative assessment of NPV. Mean (std) DSC score for predicted NPV was 85% ± 8.1% compared to ground truth. Model performance was significantly better for slices with larger prostate radii (> 24 mm) and for whole-gland rather than partial ablation slices. The predicted NPV was indistinguishable from ground truth for 31% of images. Feasibility of predicting NPV using a UNet model without MRI contrast agents was clearly established. If developed further, this could improve patient treatment outcomes and could obviate the need for contrast agents altogether.</p

QED self-energy contribution to highly-excited atomic states

We present numerical values for the self-energy shifts predicted by QED (Quantum Electrodynamics) for hydrogenlike ions (nuclear charge $60 \le Z \le 110$) with an electron in an $n=3$, 4 or 5 level with high angular momentum ($5/2\le j \le 9/2$). Applications include predictions of precision transition energies and studies of the outer-shell structure of atoms and ions.Comment: 20 pages, 5 figure

Domestication of the floating fern symbiosis Azolla

Ferns from the Azolla genus are highly productive without nitrogen fertilizer because filamentous cyanobacteria, Nostoc azollae, associated with the shoot stem cells, invade leaf cavities for N2-fixation, and reproductive structures for generational transfer. Previously used as nitrogen biofertilizer, their domestication is now considered for circular economy including the sustainable production of plant protein. The symbiosis recently transgressed into molecular research. Sequences from metagenomes of several species are available to study the contribution of the microbiome components to the symbiosis traits. A first assembly and annotation of the reference genome A. filiculoides was released; it allowed reconstruction of tannin biosynthesis, which determines Azolla biomass quality as a feed. Here, we begin with describing novel research areas required to integrate agrosystem development with domestication. We next describe first achievements to control the life cycle of the symbiosis in relation to dissemination, storage and pre-breeding. We then identify key traits of the symbiosis that will need to be considered to achieve yield stability, and discuss these traits with the little mechanistic insight available thus far. We conclude that for rapid breeding, the next vital development will be genome editing of fern host and cyanobacterial symbiont and describe our first steps towards this end