We theoretically demonstrate for the first time that a single free electron in circular or spiral motion emits twisted photons carrying well-defined orbital angular momentum along the axis of the ...electron circulation, in adding to spin angular momentum. We show that, when the electron velocity is relativistic, the radiation field contains harmonic components and the photons of lth harmonic carry lℏ total angular momentum for each. This work indicates that twisted photons are naturally emitted by free electrons and are more ubiquitous in laboratories and in nature than ever thought.
Kinetic particle‐in‐cell simulations are used to identify signatures of the electron diffusion region (EDR) and its surroundings during asymmetric magnetic reconnection. A “shoulder” in the sunward ...pointing normal electric field (EN > 0) at the reconnection magnetic field reversal is a good indicator of the EDR and is caused by magnetosheath electron meandering orbits in the vicinity of the X line. Earthward of the X line, electrons accelerated by EN form strong currents and crescent‐shaped distribution functions in the plane perpendicular to B. Just downstream of the X line, parallel electric fields create field‐aligned crescent electron distribution functions. In the immediate upstream magnetosheath, magnetic field strength, plasma density, and perpendicular electron temperatures are lower than the asymptotic state. In the magnetosphere inflow region, magnetosheath ions intrude resulting in an Earthward pointing electric field and parallel heating of magnetospheric particles. Many of the above properties persist with a guide field of at least unity.
Key Points
Where the sunward normal electric field overlaps the magnetic field reversal (the “shoulder”) is a signature of electron diffusion region
Signatures in the regions upstream of the X line establish context to find the diffusion region
Cusp‐like motion of magnetosheath electrons associated with electron acceleration produce crescent‐shaped particle distributions
Summary
Background
Application of deep‐learning technology to skin cancer classification can potentially improve the sensitivity and specificity of skin cancer screening, but the number of training ...images required for such a system is thought to be extremely large.
Objectives
To determine whether deep‐learning technology could be used to develop an efficient skin cancer classification system with a relatively small dataset of clinical images.
Methods
A deep convolutional neural network (DCNN) was trained using a dataset of 4867 clinical images obtained from 1842 patients diagnosed with skin tumours at the University of Tsukuba Hospital from 2003 to 2016. The images consisted of 14 diagnoses, including both malignant and benign conditions. Its performance was tested against 13 board‐certified dermatologists and nine dermatology trainees.
Results
The overall classification accuracy of the trained DCNN was 76·5%. The DCNN achieved 96·3% sensitivity (correctly classified malignant as malignant) and 89·5% specificity (correctly classified benign as benign). Although the accuracy of malignant or benign classification by the board‐certified dermatologists was statistically higher than that of the dermatology trainees (85·3% ± 3·7% and 74·4% ± 6·8%, P < 0·01), the DCNN achieved even greater accuracy, as high as 92·4% ± 2·1% (P < 0·001).
Conclusions
We have developed an efficient skin tumour classifier using a DCNN trained on a relatively small dataset. The DCNN classified images of skin tumours more accurately than board‐certified dermatologists. Collectively, the current system may have capabilities for screening purposes in general medical practice, particularly because it requires only a single clinical image for classification.
What's already known about this topic?
Several computer‐aided classification systems have been introduced that achieve high sensitivity for melanoma detection; however, low specificity was a trade‐off for high sensitivity.
The application of deep‐learning technology to skin cancer classification could potentially improve the sensitivity and specificity of skin cancer screening.
The number of training images required for such a system is thought to be extremely large, and compiling large datasets for rare skin conditions is difficult.
What does this study add?
Our deep convolutional neural network (DCNN), trained on only 4867 images from 1842 patients, classified images of skin tumours into 14 different diagnoses more accurately than board‐certified dermatologists.
The fluctuation range was only ± 3·2% by fivefold cross‐validation, showing the robustness of the system.
Our DCNN system requires only a single image and provides 96·3% sensitivity and 89·5% specificity in the detection of skin cancer; however, it should be validated in a prospective clinical study before use for screening purposes in general medical practice.
Linked Editorial: Janda and Soyer. Br J Dermatol 2019; 180:247–248.
Plain language summary available online
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Quantum manipulation of populations and pathways in matter by light pulses, so-called coherent control, is currently one of the hottest research areas in optical physics and photochemistry. The ...forefront of coherent control research is moving rapidly into the regime of extreme ultraviolet wavelength and attosecond temporal resolution. This advance has been enabled by the development of high harmonic generation light sources driven by intense femtosecond laser pulses and by the advent of seeded free electron laser sources. Synchrotron radiation, which is usually illustrated as being of poor temporal coherence, hitherto has not been considered as a tool for coherent control. Here we show an approach based on synchrotron radiation to study coherent control in the extreme ultraviolet and attosecond regime. We demonstrate this capability by achieving wave-packet interferometry on Rydberg wave packets generated in helium atoms.
Opsin proteins are fundamental components of animal vision whose structure largely determines the sensitivity of visual pigments to different wavelengths of light. Surprisingly little is known about ...opsin evolution in beetles, even though they are the most species rich animal group on Earth and exhibit considerable variation in visual system sensitivities. We reveal the patterns of opsin evolution across 62 beetle species and relatives. Our results show that the major insect opsin class (SW) that typically confers sensitivity to "blue" wavelengths was lost ~300 million years ago, before the origin of modern beetles. We propose that UV and LW opsin gene duplications have restored the potential for trichromacy (three separate channels for colour vision) in beetles up to 12 times and more specifically, duplications within the UV opsin class have likely led to the restoration of "blue" sensitivity up to 10 times. This finding reveals unexpected plasticity within the insect visual system and highlights its remarkable ability to evolve and adapt to the available light and visual cues present in the environment.
We report the observation of quantum interference between electron wave packets launched from the inner-shell 4d orbital of the Xe atom. Using pairs of femtosecond radiation wave packets from a ...synchrotron light source, we obtain time-domain interferograms for the inner-shell excitations. This approach enables the experimental verification and control of the quantum interference between the electron wave packets. Furthermore, the femtosecond Auger decay of the inner-shell excited state is tracked. To the best of our knowledge, this is the first observation of wave packet interference in an atomic inner-shell process, and also the first time-resolved experiment on few-femtosecond Auger decay using a synchrotron light source.
The bacterial pathogen Legionella pneumophila creates an intracellular niche permissive for its replication by extensively modulating host-cell functions using hundreds of effector proteins delivered ...by its Dot/Icm secretion system
. Among these, members of the SidE family (SidEs) regulate several cellular processes through a unique phosphoribosyl ubiquitination mechanism that bypasses the canonical ubiquitination machinery
. The activity of SidEs is regulated by another Dot/Icm effector known as SidJ
; however, the mechanism of this regulation is not completely understood
. Here we demonstrate that SidJ inhibits the activity of SidEs by inducing the covalent attachment of glutamate moieties to SdeA-a member of the SidE family-at E860, one of the catalytic residues that is required for the mono-ADP-ribosyltransferase activity involved in ubiquitin activation
. This inhibition by SidJ is spatially restricted in host cells because its activity requires the eukaryote-specific protein calmodulin (CaM). We solved a structure of SidJ-CaM in complex with AMP and found that the ATP used in this reaction is cleaved at the α-phosphate position by SidJ, which-in the absence of glutamate or modifiable SdeA-undergoes self-AMPylation. Our results reveal a mechanism of regulation in bacterial pathogenicity in which a glutamylation reaction that inhibits the activity of virulence factors is activated by host-factor-dependent acyl-adenylation.
Treatment of wide-neck bifurcation aneurysms using endovascular therapy is still challenging even with the development of treatment devices. The purpose of this investigation was to assess the safety ...and efficacy of treatment with a Woven EndoBridge (WEB) device for wide-neck bifurcation aneurysms.
All patients treated with a WEB device at our institution between May 2009 and November 2016 were retrospectively evaluated. Clinical and imaging evaluation, aneurysm occlusion status, and modified Rankin scale score were analyzed 1 day after treatment and in the short- (<6 months), mid- (<24 months), and long-term (>24 months) follow-up periods.
Forty-one cases of wide-neck aneurysms were analyzed in this study. Overall, 78.8% of the aneurysms had complete occlusion in the last follow-up, and 19.5% required retreatment with additional endovascular devices. A good clinical outcome (modified Rankin scale: 0-2) was obtained in 95.1% of the patients, and the overall treatment-related morbidity and mortality rates were 2.4% and 0.0%, respectively. The mean follow-up time was 15.3 ± 13.5 months.
The results obtained in this study suggest that treatment of wide-neck bifurcation aneurysms with a WEB device is feasible with an acceptable safety and efficacy rate.
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