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We investigate the electron quantum path interference effects during high harmonic generation in atomic gas medium driven by ultrashort chirped laser pulses. To achieve that, we identify and vary the different experimentally relevant control parameters of such a driving laser pulse influencing the high harmonic spectra. Specifically, the impact of the pulse duration, peak intensity and instantaneous frequency is studied in a self-consistent manner based on Lewenstein formalism. Simulations involving macroscopic propagation effects are also considered. The study aims to reveal the microscopic background behind a variety of interference patterns capturing important information both about the fundamental laser field and the generation process itself. The results provide guidance towards experiments with chirp control as a tool to unravel, explain and utilize the rich and complex interplay between quantum path interferences including the tuning of the periodicity of the intensity dependent oscillation of the harmonic signal, and the curvature of spectrally resolved Maker fringes., Comment: 25 pages, 8 figures, final version, New J. Phys. 23123012 (2021)

Energy-sum and angular correlation spectra of $e^+e^-$ pairs produced in the $^{3}$H(p,$\gamma$)$^{4}$He nuclear reaction have been studied at $E_p$=510, 610 and 900 keV proton energies. The main features of the spectra can be understood by taking into account the internal and external pair creations following the direct proton radiative capture by $^{3}$H. However, these processes cannot account for the observed peak around 115$^\circ$ in the angular correlation spectra. This anomalous excess of $e^+e^-$ pairs can be described by the creation and subsequent decay of a light particle during the direct capture process. The derived mass of the particle is $m_\mathrm{X}c^2$=16.94$\pm0.12 (stat) \pm 0.21 (syst)$~MeV. According to the mass and branching ratio ($B_x=5.1(13)\times10^{-6}$), this is likely the same X17 particle, which we recently suggested [Phys. Rev. Lett. 116, 052501 (2016)] for describing the anomaly observed in the decay of $^8$Be., Comment: 5 pages, 4 figures. arXiv admin note: text overlap with arXiv:1910.10459

We generate high-order harmonics in gaseous medium with tunable photon energy using time domain interferometry of double pulses in a non-collinear generation geometry. The method is based on the fact that the generated harmonics inherit certain spectral properties of the driving laser. The two temporally delayed ultrashort laser pulses, identical in all parameters, are produced by a custom-made split-and-delay unit utilizing wave front splitting without a significant energy loss. The arrangement is easy to implement in any attosecond pulse generation beamline, and is suitable for the production of an extreme ultraviolet source with simply and quickly variable central photon energy, useful for a broad range of applications., Comment: 6 pages, 5 figures, after peer-review

A critical barrier in the nephrology field is the lack of appropriate in vitro renal tubule models that allow manipulation of various mechanical factors, facilitating studies of disease pathophysiology and drug discovery. Here we report development of a novel in vitro assay system comprised of a renal tubule within an elasto-plastic extracellular matrix microenvironment. This in vitro tubule mimetic device consists of a container with two, pipette-accessible ports, filament-deposition (3D-) printed into 35 mm cell culture dishes. The container is filled with a hydrogel, such as a collagen I or fibrin gel, while a narrow masking tube is threaded through the ports. Following gelation, the masking material is pulled out leaving a tunnel within the gel. Seeding of the tunnels with M1 or MDCK renal epithelial cells through the side ports results in a monolayer with apical-basal polarity, such that laminin and fibronectin are present on the basal surface, while primary cilia project from the apical side of cells into the tubular lumen. The device is optically accessible, and can be live-imaged by phase contrast or epifluorescence microscopy. The lumen of the epithelial-lined tube can be connected through the side ports to a circulatory flow. We demonstrate that kidney epithelial cells are able to adjust the diameter of the model tubule by myosin-II dependent contractility. Furthermore, cells of the tubule are also able to remodel the surrounding hydrogel leading to budding from the main tubule. We propose that this versatile in vitro model system can be developed into a future pre-clinical tool to study pathophysiology of kidney diseases and identify therapeutic compounds., Comment: 11 pages, 4 figures

The rapid advancements in machine learning, graphics processing technologies and the availability of medical imaging data have led to a rapid increase in the use of deep learning models in the medical domain. This was exacerbated by the rapid advancements in convolutional neural network (CNN) based architectures, which were adopted by the medical imaging community to assist clinicians in disease diagnosis. Since the grand success of AlexNet in 2012, CNNs have been increasingly used in medical image analysis to improve the efficiency of human clinicians. In recent years, three-dimensional (3D) CNNs have been employed for the analysis of medical images. In this paper, we trace the history of how the 3D CNN was developed from its machine learning roots, we provide a brief mathematical description of 3D CNN and provide the preprocessing steps required for medical images before feeding them to 3D CNNs. We review the significant research in the field of 3D medical imaging analysis using 3D CNNs (and its variants) in different medical areas such as classification, segmentation, detection and localization. We conclude by discussing the challenges associated with the use of 3D CNNs in the medical imaging domain (and the use of deep learning models in general) and possible future trends in the field., Comment: Published in Sensors Journal (https://www.mdpi.com/1424-8220/20/18/5097)

This work theoretically investigates high-order harmonic generation in rare gas atoms driven by two temporally delayed ultrashort laser pulses. Apart from their temporal delay, the two pulses are identical. Using a single-atom model of the laser-matter interaction it is shown that the photon energy of the generated harmonics is controllable within the range of one eV -- a bandwidth comparable to the photon energy of the fundamental field -- by varying the time delay between the generating laser pulses. It is also demonstrated that high-order harmonics generated by double pulses have advantageous characteristics, which mimick certain properties of an extreme ultraviolet (XUV) monochromator. With the proposed method, a simpler setup at a much lower cost and comparatively higher spectral yield can be implemented in contrast to other approaches., Comment: 7 pages, 6 figures, after peer-review, corrected typo in author list

We observed electron-positron pairs from the electro-magnetically forbidden M0 transition depopulating the 21.01 MeV 0$^-$ state in $^4$He. A peak was observed in their $e^+e^-$ angular correlations at 115$^\circ$ with 7.2$\sigma$ significance, and could be described by assuming the creation and subsequent decay of a light particle with mass of $m_\mathrm{X}c^2$=16.84$\pm0.16 (stat) \pm 0.20 (syst)$ MeV and $\Gamma_\mathrm{X}$= $3.9\times 10^{-5}$ eV. According to the mass, it is likely the same X17 particle, which we recently suggested [Phys. Rev. Lett. 116, 052501 (2016)] for describing the anomaly observed in $^8$Be., Comment: 5 pages, 4 figures

Conduction and valence band states for the highly mismatched alloy (HMA) Ge:C are projected onto Ge crystal states, Ge vacancy states, and Ge/C atomic orbitals, revealing that substitutional carbon not only creates a direct bandgap, but the new conduction band is optically active. Overlap integrals of the new Ge:C conduction band with bands of pure Ge shows the new band has almost no Ge band character. C sites structurally mimic uncharged vacancies in the Ge lattice, similar to Hjalmarson's model for other HMAs. C perturbs the entire Ge band structure even at the deepest crystal core energy levels. Projection onto atomic sites shows relatively weak localization compared with other HMAs, but does show a strong anisotropy in probability distribution. L-valley conduction band states in Ge are ruled out as major contributors to the carbon state in Ge:C, both by weak inner products between these states and by a negligible effect on optical transition strength when adding C., Comment: 11 pages with references, 5 figures

Bitcoin's Lightning Network (LN) is a scalability solution for Bitcoin allowing transactions to be issued with negligible fees and settled instantly at scale. In order to use LN, funds need to be locked in payment channels on the Bitcoin blockchain (Layer-1) for subsequent use in LN (Layer-2). LN is comprised of many payment channels forming a payment channel network. LN's promise is that relatively few payment channels already enable anyone to efficiently, securely and privately route payments across the whole network. In this paper, we quantify the structural properties of LN and argue that LN's current topological properties can be ameliorated in order to improve the security of LN, enabling it to reach its true potential., Comment: Added some remarks regarding how centralized is liquidity