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Nonlinear optical (NLO) phenomena such as harmonic generation, Kerr, and Pockels effects are of great technological importance for lasers, frequency converters, modulators, switches, etc. Recently, two-dimensional (2D) materials have drawn significant attention due to their strong and unique NLO properties. Here, we describe an efficient first-principles workflow for calculating the quadratic optical response and apply it to 375 non-centrosymmetric semiconductor monolayers from the Computational 2D Materials Database (C2DB). Sorting the non-resonant nonlinearities with respect to bandgap $E_g$ reveals an upper limit proportional to $E_g^{-4}$, which is neatly explained by two distinct generic models. We identify multiple promising candidates with giant nonlinearities and bandgaps ranging from 0.4 to 5 eV, some of which approach the theoretical upper limit and greatly outperform known materials. Our comprehensive library of ab initio NLO spectra for all 375 monolayers is freely available via the C2DB website. We expect this work to pave the way for highly efficient and compact opto-electronic devices based on 2D materials., Comment: 18 pages, 5 Figures

Evidence from studies which combined 2D-3D external beam radiotherapy (EBRT) ± chemotherapy with 2D brachytherapy (BT) for anal cancer suggest favorable outcomes when compared with chemo-EBRT alone. Further improvement of results can be expected in the era of intensity modulated EBRT and MRI-guided adaptive BT. Despite this, BT is not discussed as a therapeutic option in the prominent international guidelines and its use remains limited to selected institutions. Special skills, complexity, equipment, cost and reimbursement policies have been highlighted as barriers for its wider implementation. However, these factors are relevant for modern radiotherapy in general. Therefore, it can be argued that the role of BT as a component of chemoradiation should be redefined. We describe the historical evolution and current role of BT boost for anal cancer and outline its potential in the context of combined intensity modulated EBRT, chemotherapy and MRI-guided adaptive BT.

Additional file 1: Appendix 1. Data dictionary

Additional file 2: Appendix 2. Specification of secondary models

Squamous-cell carcinoma of the anus (ASCC) is a rare disease. Barriers have been encountered to conduct clinical and translational research in this setting. Despite this, ASCC has been a prime example of collaboration amongst researchers. We performed a bibliometric analysis of ASCC-related literature of the last 20 years, exploring common patterns in research, tracking collaboration and identifying gaps. The electronic Scopus database was searched using the keywords “anal cancer”, to include manuscripts published in English, between 2000 and 2020. Data analysis was performed using R-Studio 0.98.1091 software. A machine-learning bibliometric method was applied. The bibliometrix R package was used. A total of 2322 scientific documents was found. The average annual growth rate in publication was around 40% during 2000–2020. The five most productive countries were United States of America (USA), United Kingdom (UK), France, Italy and Australia. The USA and UK had the greatest link strength of international collaboration (22.6% and 19.0%). Two main clusters of keywords for published research were identified: (a) prevention and screening and (b) overall management. Emerging topics included imaging, biomarkers and patient-reported outcomes. Further efforts are required to increase collaboration and funding to sustain future research in the setting of ASCC.

Background and purpose: Significant improvements in the treatment of anal cancer have produced a growing population of anal cancer survivors. These patients often experience late adverse effects related to their treatment. Research has revealed substantial unmet needs because of long-term symptoms and functional impairments after treatment that may negatively affect health-related quality of life. The purpose of the present guidelines is to review the scientific evidence for the management of late adverse effects after (chemo)radiotherapy ([C]RT) for anal cancer and to extrapolate knowledge from other pelvic malignancies treated with pelvic (C)RT so that they may guide the clinical management of late adverse effects. Materials and methods: Relevant studies were systematically searched in four databases from their inception to June 2020 (no language limitation) and guidelines were searched in 16 databases, focussing on bowel dysfunction, psychosocial aspects, pain, and sexual and urinary dysfunction. The guidelines were developed by a panel of experts using the Oxford Centre for Evidence-based Medicine, levels of evidence, and grades of recommendations. Scientific evidence: Late adverse effects after (C)RT for anal cancer are associated with a low overall quality of life among survivors. The most pronounced late adverse effects are bowel dysfunction (present in up to 78%), urinary dysfunction (present in up to 45%), and sexual dysfunction (present in up to 90% of men and up to 100% of women). Only indirect data on adequate treatment options of these late adverse effects for anal cancer are available. Conclusion: Quality of life and late adverse effects should be monitored systematically following treatment for anal cancer to identify patients who require further specialist evaluation or support. Increased awareness of the extent of the problem may serve to stimulate and facilitate multidisciplinary collaboration, which is often required.

Anal cancer is a relatively rare, mostly HPV-related cancer. The curative treatment consists of concurrent chemoradiation delivered with modern radiotherapy techniques. The prognosis for most patients with early localized disease is very favourable; however patients with locally advanced disease and/or HPV negative tumours are at higher risk of locoregional and distant treatment failure. Tailored approaches are presently being investigated to determine the most suitable regimen in terms of radiotherapy dose prescription, target volume selection, normal tissue avoidance, and combination therapy. Metastatic anal cancer is treated with chemotherapy aiming at prolonged survival. The role of immune therapy in the clinical setting is being investigated. There is little knowledge on the biology of anal cancer, and an urgent need for more clinical and translational research dedicated to this disease. In this article, the evidence-base for the current treatment is briefly reviewed, and perspectives on future research needs are high-lighted.

The C2DB is a highly curated open database organizing a wealth of computed properties for more than 4000 atomically thin two-dimensional (2D) materials. Here we report on new materials and properties that were added to the database since its first release in 2018. The set of new materials comprise several hundred monolayers exfoliated from experimentally known layered bulk materials, (homo)bilayers in various stacking configurations, native point defects in semiconducting monolayers, and chalcogen/halogen Janus monolayers. The new properties include exfoliation energies, Bader charges, spontaneous polarisations, Born charges, infrared polarisabilities, piezoelectric tensors, band topology invariants, exchange couplings, Raman- and second harmonic generation spectra. We also describe refinements of the employed material classification schemes, upgrades of the computational methodologies used for property evaluations, as well as significant enhancements of the data documentation and provenance. Finally, we explore the performance of Gaussian process-based regression for efficient prediction of mechanical and electronic materials properties. The combination of open access, detailed documentation, and extremely rich materials property data sets make the C2DB a unique resource that will advance the science of atomically thin materials., Comment: 30 pages, 26 figures