There’s nothing plain about projection radiography! A discussion paper

YesObjectives: Unlike the technological advances in cross-sectional imaging, the adoption of CR and DR has been relatively overlooked in terms of the additional radiographer skills and competences required for optimal practice. Furthermore, projection radiography is often referred to as basic, plain or other words suggesting simplicity or entry-level skill requirements. Radiographers’ professional identity is connected with the discourse expressed via the language used in daily practice and consequently, if the perception of projection radiography is regarded as simple practice not requiring much reflection or complex decision-making, apathy and carelessness may arise. The purpose of this narrative review was to raise projection radiography from its longstanding lowly place and re-position it as a specialist imaging field. Key findings: Danish pre-registration radiography curricula contain little mention of projection radiography and a low proportion (n ¼ 17/144; 11.8%) of Danish radiography students chose to focus on projection radiography within publicly available BSc. theses between 2016 and 2020 as compared to topics related to CT and MRI (n ¼ 60/144; 41.7%). Conclusion: By changing how we as the profession perceive the role and position of projection radiography, we can start to rebuild its lost prestige and demand a greater, more detailed and clinically relevant educational offering from academic partners. For this to commence, the language and terminology we use to describe ourselves and tasks undertaken must reflect the complexity of the profession. Implications for practice: Regardless of imaging modality, every patient should be assured that a radiographer with expertise in acquiring images of diagnostic quality undertakes their examination. Reclaiming the prestige of projection radiography may lead students and radiographers to recognize projection radiography as a demanding specialist field for the benefit of the patients

Exact Solutions of Model Hamiltonian Problems with Effective Interactions

We demonstrate with soluble models how to employ the effective Hamiltonian approach of Lee and Suzuki to obtain all the exact eigenvalues of the full Hamiltonian. We propose a new iteration scheme to obtain the effective Hamiltonian and demonstrate its convergence properties.Comment: 12 pages and 1 figur

Large-space shell-model calculations for light nuclei

An effective two-body interaction is constructed from a new Reid-like $NN$ potential for a large no-core space consisting of six major shells and is used to generate the shell-model properties for light nuclei from $A$=2 to 6. (For practical reasons, the model space is partially truncated for $A$=6.) Binding energies and other physical observables are calculated and compare favorably with experiment.Comment: prepared using LaTex, 21 manuscript pages, no figure

Bacterial chemoreceptor arrays are hexagonally packed trimers of receptor dimers networked by rings of kinase and coupling proteins

FWN – Publicaties zonder aanstelling Universiteit Leide

Spinning Strings, Black Holes and Stable Closed Timelike Geodesics

The existence and stability under linear perturbation of closed timelike curves in the spacetime associated to Schwarzschild black hole pierced by a spinning string are studied. Due to the superposition of the black hole, we find that the spinning string spacetime is deformed in such a way to allow the existence of closed timelike geodesics.Comment: 5 pages, RevTex4, some corrections and new material adde

Deterministically Driven Avalanche Models of Solar Flares

We develop and discuss the properties of a new class of lattice-based avalanche models of solar flares. These models are readily amenable to a relatively unambiguous physical interpretation in terms of slow twisting of a coronal loop. They share similarities with other avalanche models, such as the classical stick--slip self-organized critical model of earthquakes, in that they are driven globally by a fully deterministic energy loading process. The model design leads to a systematic deficit of small scale avalanches. In some portions of model space, mid-size and large avalanching behavior is scale-free, being characterized by event size distributions that have the form of power-laws with index values, which, in some parameter regimes, compare favorably to those inferred from solar EUV and X-ray flare data. For models using conservative or near-conservative redistribution rules, a population of large, quasiperiodic avalanches can also appear. Although without direct counterparts in the observational global statistics of flare energy release, this latter behavior may be relevant to recurrent flaring in individual coronal loops. This class of models could provide a basis for the prediction of large solar flares.Comment: 24 pages, 11 figures, 2 tables, accepted for publication in Solar Physic

Pion and Sigma Polarizabilities and Radiative Transitions

Fermilab E781 plans measurements of gamma-Sigma and $\gamma$-pion interactions using a 600 GeV beam of Sigmas and pions, and a virtual photon target. Pion polarizabilities and radiative transitions will be measured in this experiment. The former can test a precise prediction of chiral symmetry; the latter for a_1(1260) ----> pi + gamma is important for understanding the polarizability. The experiment also measures polarizabilities and radiative transitions for Sigma hyperons. The polarizabilities can test predictions of baryon chiral perturbation theory. The radiative transitions to the Sigma*(1385) provide a measure of the magnetic moment of the s-quark. Previous experimental and theoretical results for gamma-pi and gamma-Sigma interactions are given. The E781 experiment is described.Comment: 13 pages text (tex), Tel Aviv U. Preprint TAUP 2204-94, uses Springer-Verlag TEX macro package lecproc.cmm (appended at end of tex file, following \byebye), which requires extracting lecproc.cmm and putting this file in your directory in addition to the tex file (mmcd.tex) before tex processing. lecproc.cmm should be used following instructions and guidelines available from Springer-Verlag. Submitted to the Proceedings of Workshop on Chiral Dynamics, Massachusetts Institute of Technology, July 1994, Eds. A. Bernstein, B. Holstein. Replaced Oct. 4 to add TAUP preprint number. Replaced Oct. 12 to correct Pb target thickness from 1.3% interaction to 0.3

Explicit processing of verbal and spatial features during letter-location binding modulates oscillatory activity of a fronto-parietal network.

The present study investigated the binding of verbal and spatial features in immediate memory. In a recent study, we demonstrated incidental and asymmetrical letter-location binding effects when participants attended to letter features (but not when they attended to location features) that were associated with greater oscillatory activity over prefrontal and posterior regions during the retention period. We were interested to investigate whether the patterns of brain activity associated with the incidental binding of letters and locations observed when only the verbal feature is attended differ from those reflecting the binding resulting from the controlled/explicit processing of both verbal and spatial features. To achieve this, neural activity was recorded using magnetoencephalography (MEG) while participants performed two working memory tasks. Both tasks were identical in terms of their perceptual characteristics and only differed with respect to the task instructions. One of the tasks required participants to process both letters and locations. In the other, participants were instructed to memorize only the letters, regardless of their location. Time–frequency representation of MEG data based on the wavelet transform of the signals was calculated on a single trial basis during the maintenance period of both tasks. Critically, despite equivalent behavioural binding effects in both tasks, single and dual feature encoding relied on different neuroanatomical and neural oscillatory correlates. We propose that enhanced activation of an anterior–posterior dorsal network observed in the task requiring the processing of both features reflects the necessity for allocating greater resources to intentionally process verbal and spatial features in this task

Direct Observation of Charge Transfer between NOx and Monolayer MoS2 by Operando Scanning Photoelectron Microscopy

Atomically thin transition metal dichalcogenides MoS2, WSe2, etc. have long been touted as promising materials for gas detection because of their tunable band gaps; however, the sensing mechanism, based on a charge transfer process, has not been fully explored. Here, we directly observe the effect of this charge transfer on the doping levels in MoS2 upon exposure to NOx by performing scanning photoelectron microscopy SPEM on a monolayer MoS2 transistor under bias conditions in a gas environment. By a comparison of the operando SPEM maps of the transistor with and without exposure to NOx gas, a downward shift in the Fermi level position could be detected, consistent with NOx gas making the MoS2 channel less n typ