CAPTCHaStar! A novel CAPTCHA based on interactive shape discovery

Over the last years, most websites on which users can register (e.g., email providers and social networks) adopted CAPTCHAs (Completely Automated Public Turing test to tell Computers and Humans Apart) as a countermeasure against automated attacks. The battle of wits between designers and attackers of CAPTCHAs led to current ones being annoying and hard to solve for users, while still being vulnerable to automated attacks. In this paper, we propose CAPTCHaStar, a new image-based CAPTCHA that relies on user interaction. This novel CAPTCHA leverages the innate human ability to recognize shapes in a confused environment. We assess the effectiveness of our proposal for the two key aspects for CAPTCHAs, i.e., usability, and resiliency to automated attacks. In particular, we evaluated the usability, carrying out a thorough user study, and we tested the resiliency of our proposal against several types of automated attacks: traditional ones; designed ad-hoc for our proposal; and based on machine learning. Compared to the state of the art, our proposal is more user friendly (e.g., only some 35% of the users prefer current solutions, such as text-based CAPTCHAs) and more resilient to automated attacks.Comment: 15 page

Current concepts in the treatment of intra-articular calcaneal fractures: results of a nationwide survey

The treatment of intra-articular calcaneal fractures is controversial and randomised clinical trials are scarce. Moreover, the socio-economic cost remains unclear. The aim of this study was to estimate the incidence, treatment preferences and socio-economic cost of this complex fracture in the Netherlands. This data may aid in planning future clinical trials and support education. The method of study was of a cross-sectional survey design. A written survey was sent to one representative of both the traumatology and the orthopaedic staff in each hospital in the Netherlands. Data on incidence, treatment modalities, complications and follow-up strategies were recorded. The socio-economic cost was calculated. The average response rate was 70%. Fracture classifications, mostly by Sanders and Essex-Lopresti, were applied by 29%. Annually, 920 intra-articular calcaneal fractures (0.4% incidence rate) were treated, mainly with ORIF (46%), conservative (39%) and percutaneous (10%) treatment. The average non-weight-bearing mobilisation was 9 weeks (SD 2 weeks). An outcome score, mainly AOFAS, was documented by 7%. A secondary arthrodesis was performed in 21% of patients. The socio-economic cost was estimated to be €21.5–30.7 million. Dutch intra-articular calcaneal fracture incidence is at least 0.4% of all fractures presenting to hospitals. Better insight into treatment modalities currently employed and costs in the Netherlands was obtained

The many possible climates from the Paris Agreement’s aim of 1.5 °C warming

The United Nations’ Paris Agreement includes the aim of pursuing efforts to limit global warming to only 1.5 °C above pre-industrial levels. However, it is not clear what the resulting climate would look like across the globe and over time. Here we show that trajectories towards a ‘1.5 °C warmer world’ may result in vastly different outcomes at regional scales, owing to variations in the pace and location of climate change and their interactions with society’s mitigation, adaptation and vulnerabilities to climate change. Pursuing policies that are considered to be consistent with the 1.5 °C aim will not completely remove the risk of global temperatures being much higher or of some regional extremes reaching dangerous levels for ecosystems and societies over the coming decades

Dual modification of Alzheimer’s disease PHF-tau protein by lysine methylation and ubiquitylation: a mass spectrometry approach

In sporadic Alzheimer’s disease (AD), neurofibrillary lesion formation is preceded by extensive post-translational modification of the microtubule associated protein tau. To identify the modification signature associated with tau lesion formation at single amino acid resolution, immunopurified paired helical filaments were isolated from AD brain and subjected to nanoflow liquid chromatography–tandem mass spectrometry analysis. The resulting spectra identified monomethylation of lysine residues as a new tau modification. The methyl-lysine was distributed among seven residues located in the projection and microtubule binding repeat regions of tau protein, with one site, K254, being a substrate for a competing lysine modification, ubiquitylation. To characterize methyl lysine content in intact tissue, hippocampal sections prepared from post mortem late-stage AD cases were subjected to double-label confocal fluorescence microscopy using anti-tau and anti-methyl lysine antibodies. Anti-methyl lysine immunoreactivity colocalized with 78 ± 13% of neurofibrillary tangles in these specimens. Together these data provide the first evidence that tau in neurofibrillary lesions is post-translationally modified by lysine methylation