Two philosophies for solving non-linear equations in algebraic cryptanalysis

Algebraic Cryptanalysis [45] is concerned with solving of particular systems of multivariate non-linear equations which occur in cryptanalysis. Many different methods for solving such problems have been proposed in cryptanalytic literature: XL and XSL method, Gröbner bases, SAT solvers, as well as many other. In this paper we survey these methods and point out that the main working principle in all of them is essentially the same. One quantity grows faster than another quantity which leads to a “phase transition” and the problem becomes efficiently solvable. We illustrate this with examples from both symmetric and asymmetric cryptanalysis. In this paper we point out that there exists a second (more) general way of formulating algebraic attacks through dedicated coding techniques which involve redundancy with addition of new variables. This opens numerous new possibilities for the attackers and leads to interesting optimization problems where the existence of interesting equations may be somewhat deliberately engineered by the attacker

General relativistic null-cone evolutions with a high-order scheme

We present a high-order scheme for solving the full non-linear Einstein equations on characteristic null hypersurfaces using the framework established by Bondi and Sachs. This formalism allows asymptotically flat spaces to be represented on a finite, compactified grid, and is thus ideal for far-field studies of gravitational radiation. We have designed an algorithm based on 4th-order radial integration and finite differencing, and a spectral representation of angular components. The scheme can offer significantly more accuracy with relatively low computational cost compared to previous methods as a result of the higher-order discretization. Based on a newly implemented code, we show that the new numerical scheme remains stable and is convergent at the expected order of accuracy.Comment: 24 pages, 3 figure

The role of social capital in women's sexual and reproductive health and rights in humanitarian settings: a systematic review of qualitative studies.

Background Social capital is an important social determinant of women’s sexual and reproductive health and rights. Little research has been conducted to understand the role of social capital in women’s sexual and reproductive health and how this can be harnessed to improve health in humanitarian settings. We synthesised the evidence to examine the nexus of women’s sexual and reproductive health and rights and social capital in humanitarian contexts. Methods We undertook a systematic review of qualitative studies. The preferred reporting items for systematic review and meta-analysis guidelines were used to identify peer-reviewed, qualitative studies conducted in humanitarian settings published since 1999. We searched CINAHL, MEDLINE, ProQuest Health & Medicine, PubMed, Embase and Web of science core collection and assessed quality using the Critical Appraisal Skills Programme tool. We used a meta-ethnographic approach to synthesise and analyse the data. Findings Of 6749 initially identified studies, we included 19 studies, of which 18 were in conflict-related humanitarian settings and one in a natural disaster setting. The analysis revealed that the main form of social capital available to women was bonding social capital or strong links between people within groups of similar characteristics. There was limited use of bridging social capital, consisting of weaker connections between people of approximately equal status and power but with different characteristics. The primary social capital mechanisms that played a role in women’s sexual and reproductive health and rights were social support, informal social control and collective action. Depending on the nature of the values, norms and traditions shared by network members, these social capital mechanisms had the potential to both facilitate and hinder positive health outcomes for women. Conclusions These findings demonstrate the importance of understanding social capital in planning sexual and reproductive health responses in humanitarian settings. The analysis highlights the need to investigate social capital from an individual perspective to expose the intra-network dynamics that shape women’s experiences. Insights could help inform community-based preparedness and response programs aimed at improving the demand for and access to quality sexual and reproductive health services in humanitarian settings

Electronic clinical practice guidelines: Current status and future prospects in Hong Kong

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Probe-based Rapid Hybrid Hyperspectral and Tissue Surface Imaging Aided by Fully Convolutional Networks

Tissue surface shape and reflectance spectra provide rich intra-operative information useful in surgical guidance. We propose a hybrid system which displays an endoscopic image with a fast joint inspection of tissue surface shape using structured light (SL) and hyperspectral imaging (HSI). For SL a miniature fibre probe is used to project a coloured spot pattern onto the tissue surface. In HSI mode standard endoscopic illumination is used, with the fibre probe collecting reflected light and encoding the spatial information into a linear format that can be imaged onto the slit of a spectrograph. Correspondence between the arrangement of fibres at the distal and proximal ends of the bundle was found using spectral encoding. Then during pattern decoding, a fully convolutional network (FCN) was used for spot detection, followed by a matching propagation algorithm for spot identification. This method enabled fast reconstruction (12 frames per second) using a GPU. The hyperspectral image was combined with the white light image and the reconstructed surface, showing the spectral information of different areas. Validation of this system using phantom and ex vivo experiments has been demonstrated.Comment: This paper has been submitted to MICCAI2016 on 17 March, 2016, and conditionally accepted on 2 June, 201

Repeated ischaemic preconditioning: A novel therapeutic intervention and potential underlying mechanisms.

Ischaemic preconditioning (IPC) refers to the phenomenon that short periods of cyclical tissue ischaemia confer subsequent protection against ischaemia-induced injury. As a consequence, IPC can ameliorate the myocardial damage following infarction and reduce infarct size. The ability of IPC to confer remote protection makes IPC a potentially feasible cardioprotective strategy. In this review, we discuss the concept that repeatedly exposing tissue to IPC may increase the "dose" of protection, and subsequently lead to enhanced protection against ischaemia-induced myocardial injury. This may be relevant for clinical populations, who demonstrate attenuated efficacy of IPC to prevent or attenuate ischaemic injury (and therefore myocardial infarct size). Furthermore, episodic IPC facilitates repeated exposure to local (e.g. shear stress) and systemic (e.g. hormones, cytokines, blood-borne substances) stimuli, which may induce improvement in vascular function and health. Such adaptation may contribute to prevention of cardio- and cerebro-vascular events. The clinical benefits of repeated IPC may, therefore, result from both the prevention of ischaemic events and attenuation of their consequences. We provide an overview of the literature pertaining to the impact of repeated IPC on cardiovascular function, related to both local and or remote adaptation, as well as potential clinical implications. This article is protected by copyright. All rights reserved

Trace elements in Corallium spp. as indicators for origin and habitat

Precious corals have been commercially exploited for many centuries around the world. The skeletons of these corals consist of calcium carbonate, and have been used as amulets or gemstones since ancient times. Different Corallium species of Coralidae family (e.g., Corallium rubrum, Corallium elatus, Corallium konojoi, and Paracorellium japonicum) were collected from different locations of the Mediterranean Sea (off Italy) and Pacific Ocean (off Japan and off Midway Island), and trace elements in their skeletons were analyzed. Results show that trace element concentrations in the skeletons of Corallium spp. were attributable to their habitat and origin. In particular, Mg/Ca and Ba/Ca ratios in the skeletons of Corallium spp. from the Mediterranean Sea and Japanese and the Midway Islands' waters were found to be habitat-specific. This study also reveals that trace elements in the skeletons can be used as ecological indicator of the coral's origin, and are expected to play an important part in the cultural study and sustainable management of precious corals. Findings of this study will also be of great relevance to the coral industry to authenticate and identify the habitat and origin of the corals. © 2012 Elsevier B.V

Systematic Construction of Nonlinear Product Attacks on Block Ciphers

A major open problem in block cipher cryptanalysis is discovery of new invariant properties of complex type. Recent papers show that this can be achieved for SCREAM, Midori64, MANTIS-4, T-310 or for DES with modified S-boxes. Until now such attacks are hard to find and seem to happen by some sort of incredible coincidence. In this paper we abstract the attack from any particular block cipher. We study these attacks in terms of transformations on multivariate polynomials. We shall demonstrate how numerous variables including key variables may sometimes be eliminated and at the end two very complex Boolean polynomials will become equal. We present a general construction of an attack where multiply all the polynomials lying on one or several cycles. Then under suitable conditions the non-linear functions involved will be eliminated totally. We obtain a periodic invariant property holding for any number of rounds. A major difficulty with invariant attacks is that they typically work only for some keys. In T-310 our attack works for any key and also in spite of the presence of round constants

Adherence to the test, trace, and isolate system in the UK: results from 37 nationally representative surveys

Objective: To investigate rates of adherence to the UK’s test, trace, and isolate system over the initial 11 months of the covid-19 pandemic. Design: Series of cross sectional online surveys. Setting: 37 nationally representative surveys in the UK, 2 March 2020 to 27 January 2021. Participants: 74 697 responses from 53 880 people living in the UK, aged 16 years or older (37 survey waves, about 2000 participants in each wave). Main outcome measures: Identification of the main symptoms of covid-19 (cough, high temperature or fever, and loss of sense of smell or taste), self-reported adherence to self-isolation if symptoms were present and intention to self-isolate if symptoms were to develop, requesting a test for covid-19 if symptoms were present and intention to request a test if symptoms were to develop, and intention to share details of close contacts. Results: Only 51.5% of participants (95% confidence interval 51.0% to 51.9%, n=26 030/50  570) identified the main symptoms of covid-19; the corresponding values in the most recent wave of data collection (25-27 January 2021) were 50.8% (48.6% to 53.0%, n=1019/2007). Across all waves, duration adjusted adherence to full self-isolation was 42.5% (95% confidence interval 39.7% to 45.2%, n=515/1213); in the most recent wave of data collection (25-27 January 2021), it was 51.8% (40.8% to 62.8%, n=43/83). Across all waves, requesting a test for covid-19 was 18.0% (95% confidence interval 16.6% to 19.3%, n=552/3068), increasing to 22.2% (14.6% to 29.9%, n=26/117) from 25 to 27 January. Across all waves, intention to share details of close contacts was 79.1% (95% confidence interval 78.8% to 79.5%, n=36 145/45 680), increasing to 81.9% (80.1% to 83.6%, n=1547/1890) from 25 to 27 January. Non-adherence was associated with being male, younger age, having a dependent child in the household, lower socioeconomic grade, greater financial hardship during the pandemic, and working in a key sector. Conclusions: Levels of adherence to test, trace, and isolate are low, although some improvement has occurred over time. Practical support and financial reimbursement are likely to improve adherence. Targeting messaging and policies to men, younger age groups, and key workers might also be necessary