Streaking single-electron ionization in open-shell molecules driven by X-ray pulses

We obtain continuum molecular wavefunctions for open-shell molecules in the Hartree-Fock framework. We do so while accounting for the singlet or triplet total spin symmetry of the molecular ion, that is, of the open-shell orbital and the initial orbital where the electron ionizes from. Using these continuum wavefunctions, we obtain the dipole matrix elements for a core electron that ionizes due to single-photon absorption by a linearly polarized X-ray pulse. After ionization from the X-ray pulse, we control or streak the electron dynamics using a circularly polarized infrared (IR) pulse. For a high intensity IR pulse and photon energies of the X-ray pulse close to the ionization threshold of the $1{\sigma}$ or $2{\sigma}$ orbitals, we achieve control of the angle of escape of the ionizing electron by varying the phase delay between the X-ray and IR pulses. For a low intensity IR pulse, we obtain final electron momenta distributions on the plane of the IR pulse and we find that many features of these distributions correspond to the angular patterns of electron escape solely due to the X-ray pulse.Comment: 13 pages, 7 figure

Identifying key mechanisms leading to visual recognition errors for missed colorectal polyps using eye-tracking technology

Background and Aim Lack of visual recognition of colorectal polyps may lead to interval cancers. The mechanisms contributing to perceptual variation, particularly for subtle and advanced colorectal neoplasia, have scarcely been investigated. We aimed to evaluate visual recognition errors and provide novel mechanistic insights. Methods Eleven participants (seven trainees and four medical students) evaluated images from the UCL polyp perception dataset, containing 25 polyps, using eye-tracking equipment. Gaze errors were defined as those where the lesion was not observed according to eye-tracking technology. Cognitive errors occurred when lesions were observed but not recognized as polyps by participants. A video study was also performed including 39 subtle polyps, where polyp recognition performance was compared with a convolutional neural network. Results Cognitive errors occurred more frequently than gaze errors overall (65.6%), with a significantly higher proportion in trainees (P = 0.0264). In the video validation, the convolutional neural network detected significantly more polyps than trainees and medical students, with per-polyp sensitivities of 79.5%, 30.0%, and 15.4%, respectively. Conclusions Cognitive errors were the most common reason for visual recognition errors. The impact of interventions such as artificial intelligence, particularly on different types of perceptual errors, needs further investigation including potential effects on learning curves. To facilitate future research, a publicly accessible visual perception colonoscopy polyp database was created

Performance of artificial intelligence for detection of subtle and advanced colorectal neoplasia

OBJECTIVES: There is uncertainty regarding the efficacy of artificial intelligence (AI) software to detect advanced subtle neoplasia, particularly flat lesions and sessile serrated lesions (SSLs), due to low prevalence in testing datasets and prospective trials. This has been highlighted as a top research priority for the field. METHODS: An AI algorithm was evaluated on 4 video test datasets containing 173 polyps (35,114 polyp positive frames and 634,988 polyp-negative frames) specifically enriched with flat lesions and SSLs, including a challenging dataset containing subtle advanced neoplasia. The challenging dataset was also evaluated by 8 endoscopists (4 independent, 4 trainees, according to Joint Advisory Group on GI endoscopy (JAG) standards in United Kingdom). RESULTS: In the first 2 video datasets, the algorithm achieved per-polyp sensitivities of 100% and 98.9%. Per-frame sensitivities were 84.1% and 85.2% . In the subtle dataset, the algorithm detected a significantly higher number of polyps (P<0.0001), compared to JAG-independent and trainee endoscopists, achieving per-polyp sensitivities of 79.5%, 37.2% and 11.5% respectively. Furthermore, when considering subtle polyps detected by both the algorithm and at least one endoscopist, the AI detected polyps significantly faster on average. CONCLUSIONS: The AI based algorithm achieved high per-polyp sensitivities for advanced colorectal neoplasia, including flat lesions and SSLs, outperforming both JAG independent and trainees on a very challenging dataset containing subtle lesions that could have been overlooked easily and contribute to interval colorectal cancer. Further prospective trials should evaluate AI to detect subtle advanced neoplasia in higher risk populations for colorectal cancer

Gastrin-Releasing Peptide Signaling Plays a Limited and Subtle Role in Amygdala Physiology and Aversive Memory

Links between synaptic plasticity in the lateral amygdala (LA) and Pavlovian fear learning are well established. Neuropeptides including gastrin-releasing peptide (GRP) can modulate LA function. GRP increases inhibition in the LA and mice lacking the GRP receptor (GRPR KO) show more pronounced and persistent fear after single-trial associative learning. Here, we confirmed these initial findings and examined whether they extrapolate to more aspects of amygdala physiology and to other forms of aversive associative learning. GRP application in brain slices from wildtype but not GRPR KO mice increased spontaneous inhibitory activity in LA pyramidal neurons. In amygdala slices from GRPR KO mice, GRP did not increase inhibitory activity. In comparison to wildtype, short- but not long-term plasticity was increased in the cortico-lateral amygdala (LA) pathway of GRPR KO amygdala slices, whereas no changes were detected in the thalamo-LA pathway. In addition, GRPR KO mice showed enhanced fear evoked by single-trial conditioning and reduced spontaneous firing of neurons in the central nucleus of the amygdala (CeA). Altogether, these results are consistent with a potentially important modulatory role of GRP/GRPR signaling in the amygdala. However, administration of GRP or the GRPR antagonist (D-Phe6, Leu-NHEt13, des-Met14)-Bombesin (6–14) did not affect amygdala LTP in brain slices, nor did they affect the expression of conditioned fear following intra-amygdala administration. GRPR KO mice also failed to show differences in fear expression and extinction after multiple-trial fear conditioning, and there were no differences in conditioned taste aversion or gustatory neophobia. Collectively, our data indicate that GRP/GRPR signaling modulates amygdala physiology in a paradigm-specific fashion that likely is insufficient to generate therapeutic effects across amygdala-dependent disorders

Characterization of a fluvial aquifer at a range of depths and scales: the Triassic St Bees Sandstone Formation, Cumbria, UK

Fluvial sedimentary successions represent porous media that host groundwater and geothermal resources. Additionally, they overlie crystalline rocks hosting nuclear waste repositories in rift settings. The permeability characteristics of an arenaceous fluvial succession, the Triassic St Bees Sandstone Formation in England (UK), are described, from core-plug to well-test scale up to ~1 km depth. Within such lithified successions, dissolution associated with the circulation of meteoric water results in increased permeability (K~10−1–100 m/day) to depths of at least 150 m below ground level (BGL) in aquifer systems that are subject to rapid groundwater circulation. Thus, contaminant transport is likely to occur at relatively high rates. In a deeper investigation (> 150 m depth), where the aquifer has not been subjected to rapid groundwater circulation, well-test-scale hydraulic conductivity is lower, decreasing from K~10−2 m/day at 150–400 m BGL to 10−3 m/day down-dip at ~1 km BGL, where the pore fluid is hypersaline. Here, pore-scale permeability becomes progressively dominant with increasing lithostatic load. Notably, this work investigates a sandstone aquifer of fluvial origin at investigation depths consistent with highly enthalpy geothermal reservoirs (~0.7–1.1 km). At such depths, intergranular flow dominates in unfaulted areas with only minor contribution by bedding plane fractures. However, extensional faults represent preferential flow pathways, due to presence of high connective open fractures. Therefore, such faults may (1) drive nuclear waste contaminants towards the highly permeable shallow (< 150 m BGL) zone of the aquifer, and (2) influence fluid recovery in geothermal fields

Discovertebral (Andersson) lesions of the spine in ankylosing spondylitis revisited

A well-known complication in patients with ankylosing spondylitis (AS) is the development of localised vertebral or discovertebral lesions of the spine, which was first described by Andersson in 1937. Since then, many different terms are used in literature to refer to these localised lesions of the spine, including the eponym ‘Andersson lesion’ (AL). The use of different terms reflects an ongoing debate on the exact aetiology of the AL. In the current study, we performed an extensive review of the literature in order to align communication on aetiology, diagnosis and management between treating physicians. AL may result from inflammation or (stress-) fractures of the complete ankylosed spine. There is no evidence for an infectious origin. Regardless of the exact aetiology, a final common pathway exists, in which mechanical stresses prevent the lesion from fusion and provoke the development of pseudarthrosis. The diagnosis of AL is established on conventional radiography, but computed tomography and magnetic resonance imaging both provide additional information. There is no indication for a diagnostic biopsy. Surgical instrumentation and fusion is considered the principle management in symptomatic AL that fails to resolve from a conservative treatment. We advise to use the term Andersson lesion for these spinal lesions in patients with AS

Unveiling coastal aeolian facies in the Upper Jurassic record of eastern Iberia: new insights from the dinosaur fossil–bearing Villar del Arzobispo Fm (Teruel, E Spain)

Trabajo presentado en el 33rd International Meeting of Sedimentology y 16ème Congrès Français de Sédimentologie (2017), celebrado en Toulouse (Francia), del 10 al 12 de octubre de 2017The Upper Jurassic Villar del Arzobispo Fm is a mixed siliciclastic-carbonate succession that crops out in the Riodeva area (Teruel, eastern Spain) and preserves abundant dinosaur fossils. In this area, the succession has been interpreted as representing the preserved accumulation of an inner carbonate platform that evolved upwards into a predominantly siliciclastic fluvial system with minor marine carbonate incursions. However, preliminary studies performed in this area have revealed the presence of aeolian deposits intercalated with tidal, scarce alluvial and marine deposits, suggesting deposition in a coastal plain setting, rather than a fluvial system. In this work, we analyse the aeolian deposits of the Villar del Arzobispo Fm to reconstruct the depositional environments of the unit. For the first time, we describe the occurrence of dome-shaped aeolian dunes in the Mesozoic record of Iberia. The studied deposits are arranged in metre-thick sandstone beds (up to 10 m). Beds exhibit flat bases and tops, and a lateral continuity up to 300 m and occur interbedded with edaphized, reddish siliciclastic mudstone. Two facies associations are distinguished. The Aeolian dune facies association consists on fine-to medium-grained, well-to very well-sorted sandstone, which displays different types of large-scale cross-bedding. (1) Tangential cross-bedding is arranged in up to 2 m-thick sets, displaying tangential foresets (angles of 20-35°) and reactivation surfaces; internally, it is formed by mm-to cm-thick laminae that pinch out upwards and downwards. (2) Low-angle cross-bedding is arranged in sets up to 2.7 m-thick, displaying low-angle foresets (< 15°), laterally extensive bottomsets and reactivation surfaces; internally, it consists of mm-to cm-thick laterally continuous laminae. (3) Dome-shaped cross-bedding is arranged in up to 4 m-thick sets, consisting of convex-up, steeply dipping foresets (up to 35°) with preserved topsets. These features are typical of migrating aeolian dunes. Specifically, the tangential cross-bedding may result from the accumulation of grainflow packages on the lee side of dunes exceeding the angle of repose, whereas the low-angle cross-bedding may result from the accumulation of wind ripples in the dune plinths. Deposits displaying steeply dipping, convex-up foresets with preserved topsets are interpreted as dome-shaped dunes. The Interdune facies association comprises two facies. (1) Near-horizontally laminated sandstone with mm-to cm-thick layers of carbonaceous detritus occurring as drapes; these drapes commonly pass updip into the bottomsets and rarely the lower part of the foresets of aforementioned aeolian dune deposits. (2) Decimetrethick, fine-grained, climbing-rippled sandstone beds, interbedded with tangential cross-bedded sandstone. These facies suggest deposition in wet aeolian interdunes that were subjected to episodic aqueous floods. The fact that the studied deposits are interbedded with tidal and marine deposits, suggests that interdune flood events might have been caused by storms or spring tides in this coastal palaeoenvironment. Ephemeral flash flood events likely also occurred. Collectively, these facies relationships indicate that, during the Late Jurassic, coastal aeolian dunes developed in a coastal plain setting in eastern Iberia; this plain was also influenced by tides and affected by episodic alluvial depositionFunded by the Spanish project CGL2014-52670-P, Government of Aragón (FOCONTUR-E62) and a predoctoral scholarship (FPU13/02978).Peer reviewe