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We conducted a multicentre observational study in people living with HIV (PLHIV) on antiretroviral therapy in Alicante (Spain) from 2019 to 2020 aiming to analyse the prevalence of abuse and assess treatment adherence according to this variable. We used the Abuse Assessment Screen tool, the simplified medication adherence questionnaire and the medication possession ratio to assess outcomes.. Of the 161 included PLHIV, 53 (32.9%) had suffered abuse (27 emotional abuse, 6 physical abuse, 3 sexual abuse, 13 emotional and physical abuse, 4 unknown type). Seven (4.3%) had suffered abuse in the last year (5 emotional, 2 physical). Abuse had lasted a median of 48 months (interquartile range 12-81). HIV status was considered as a cause of violence by 9.4% of victims. In the multivariable analysis, only abuse was independently associated with non-adherence [adjusted odds ratio (aOR) 3.92; 95% confidence interval (CI) 1.80-8.84

We conducted a multicentre observational study in people living with HIV (PLHIV) on antiretroviral therapy in Alicante (Spain) from 2019 to 2020 aiming to analyse the prevalence of abuse and assess treatment adherence according to this variable. We used the Abuse Assessment Screen tool, the simplified medication adherence questionnaire and the medication possession ratio to assess outcomes.. Of the 161 included PLHIV, 53 (32.9%) had suffered abuse (27 emotional abuse, 6 physical abuse, 3 sexual abuse, 13 emotional and physical abuse, 4 unknown type). Seven (4.3%) had suffered abuse in the last year (5 emotional, 2 physical). Abuse had lasted a median of 48 months (interquartile range 12-81). HIV status was considered as a cause of violence by 9.4% of victims. In the multivariable analysis, only abuse was independently associated with non-adherence [adjusted odds ratio (aOR) 3.92; 95% confidence interval (CI) 1.80-8.84; p = 0.0007]. Abuse (aOR 6.14; 95% CI 1.63-27.70; p = 0.001) and previous incarceration (aOR 15.08 95% CI 2.71-104.71; p = 0.003) were associated with detectable viral load. In conclusion, the prevalence of abuse is high in PLHIV, hampering adherence and virological success. Abuse screening tools should be incorporated into routine HIV care.

This article presents a review of the literature on the information filtering methods used in current Recommender Systems, with an emphasis on recommendation Systems based on content, and those based on collaboration. The study starts from the classic taxonomy of filtering methods: content-based and collaboration-based, their mechanisms are explored, advantages and areas of opportunity are cited, and knowledge-based filtering is also incorporated. It concludes with an easy-to-understand literary review that seeks to provide the reader with an overview of the classic mechanisms behind Recommendation Systems, and some of the techniques widely used in the models. The study of modern techniques that could be used to improve the recommendations in the different types of filtering, such as those that use mixed approaches and those that use knowledge graphs, is left in perspective.

While messaging systems with strong security guarantees are widely used in practice, designing a protocol that scales efficiently to large groups and enjoys similar security guarantees remains largely open. The two existing proposals to date are ART (Cohn-Gordon et al., CCS18) and TreeKEM (IETF, The Messaging Layer Security Protocol, draft). TreeKEM is the currently considered candidate by the IETF MLS working group, but dynamic group operations (i.e. adding and removing users) can cause efficiency issues. In this paper we formalize and analyze a variant of TreeKEM which we term Tainted TreeKEM (TTKEM for short). The basic idea underlying TTKEM was suggested by Millican (MLS mailing list, February 2018). This version is more efficient than TreeKEM for some natural distributions of group operations, we quantify this through simulations.Our second contribution is two security proofs for TTKEM which establish post compromise and forward secrecy even against adaptive attackers. The security loss (to the underlying PKE) in the Random Oracle Model is a polynomial factor, and a quasipolynomial one in the Standard Model. Our proofs can be adapted to TreeKEM as well. Before our work no security proof for any TreeKEM-like protocol establishing tight security against an adversary who can adaptively choose the sequence of operations was known. We also are the first to prove (or even formalize) active security where the server can arbitrarily deviate from the protocol specification. Proving fully active security – where also the users can arbitrarily deviate – remains open.

Automated contract tracing aims at supporting manual contact tracing during pandemics by alerting users of encounters with infected people. There are currently many proposals for protocols (like the “decentralized” DP-3T and PACT or the “centralized” ROBERT and DESIRE) to be run on mobile phones, where the basic idea is to regularly broadcast (using low energy Bluetooth) some values, and at the same time store (a function of) incoming messages broadcasted by users in their proximity. In the existing proposals one can trigger false positives on a massive scale by an “inverse-Sybil” attack, where a large number of devices (malicious users or hacked phones) pretend to be the same user, such that later, just a single person needs to be diagnosed (and allowed to upload) to trigger an alert for all users who were in proximity to any of this large group of devices.

Key trees are often the best solution in terms of transmission cost and storage requirements for managing keys in a setting where a group needs to share a secret key, while being able to efficiently rotate the key material of users (in order to recover from a potential compromise, or to add or remove users). Applications include multicast encryption protocols like LKH (Logical Key Hierarchies) or group messaging like the current IETF proposal TreeKEM. A key tree is a (typically balanced) binary tree, where each node is identified with a key: leaf nodes hold users’ secret keys while the root is the shared group key. For a group of size N, each user just holds log(N) keys (the keys on the path from its leaf to the root) and its entire key material can be rotated by broadcasting 2log(N) ciphertexts (encrypting each fresh key on the path under the keys of its parents). In this work we consider the natural setting where we have many groups with partially overlapping sets of users, and ask if we can find solutions where the cost of rotating a key is better than in the trivial one where we have a separate key tree for each group. We show that in an asymptotic setting (where the number m of groups is fixed while the number N of users grows) there exist more general key graphs whose cost converges to the cost of a single group, thus saving a factor linear in the number of groups over the trivial solution. As our asymptotic “solution” converges very slowly and performs poorly on concrete examples, we propose an algorithm that uses a natural heuristic to compute a key graph for any given group structure. Our algorithm combines two greedy algorithms, and is thus very efficient: it first converts the group structure into a “lattice graph”, which is then turned into a key graph by repeatedly applying the algorithm for constructing a Huffman code. To better understand how far our proposal is from an optimal solution, we prove lower bounds on the update cost of continuous group-key agreement and multicast encryption in a symbolic model admitting (asymmetric) encryption, pseudorandom generators, and secret sharing as building blocks. ISSN:0302-9743 ISSN:1611-3349

Hybrid wheat varieties give higher yields than conventional lines but are difficult to produce due to a lack of effective control of male fertility in breeding lines. One promising system involves the Rf1 and Rf3 genes that restore fertility of wheat plants carrying Triticum timopheevii-type cytoplasmic male sterility (T-CMS). Here, by genetic mapping and comparative sequence analyses, we identify Rf1 and Rf3 candidates that can restore normal pollen production in transgenic wheat plants carrying T-CMS. We show that Rf1 and Rf3 bind to the mitochondrial orf279 transcript and induce cleavage, preventing expression of the CMS trait. The identification of restorer genes in wheat is an important step towards the development of hybrid wheat varieties based on a CMS-Rf system. The characterisation of their mode of action brings insights into the molecular basis of CMS and fertility restoration in plants., The development of hybrid wheat cultivars is hampered by the lack of an effective way to control male fertility in breeding lines. Here, the authors report the identification of two restorer-of-fertility genes Rf1 and Rf3 that can restore fertility of wheat plants carrying Triticum timopheevii-type cytoplasmic male sterility.