PNAEQ - 13 years of post-analytical EQAS in Portugal

In the last 13 years, PNAEQ provided a specific program on post-analytical phase. In order to raise the offer of schemes in areas like Thrombosis/ Haemostasis, PNAEQ has established a consortium with ECAT Foundation distributing two more schemes: Post- Analytical Platelet Function and Pre- and Post-Analytical in Haemostasis. Furthermore, five of the analytical schemes organized by PNAEQ include a post-analytical interpretation, such as Blood Morphology, Hemoglobinopathies, Hydatidose, Rubella and Toxoplasmosis. The main objective of implementing specific and integrated programs on post-analytical phase is to evaluate the performance of laboratories on these matters in order to improve their quality service. The specific program on post-analytical phase provided by PNAEQ comprises 6 types of surveys: audits (vertical and presential), case simulation, case-study, document evaluation, quality indicators and questionnaires. Each survey represents a different tool to evaluate several items of the post-analytical process (Table 1), as well as the laboratory collaborators involved in each task (Figure 1). The items in evaluation are annually selected in the PNAEQ Working Group on Pre- and Post-Analytical Phase (created in 2015) and in compliance with the Portuguese Legislation and the ISO 15189:2012(E). Since 2007 PNAEQ has distributed 6 types of tools in the Post-Analytical Phase EQA, stabilizing in 3 of them in the last five years: Audits, Case Simulation and Quality Indicators. The participation rate has been increasing since 2015, which can be due to the multiple actions performed by PNAEQ Working Group on Pre- and Post-Analytical Phase. In addition, the Case Simulation surveys are the most participated (74% average) since the participation depends on PNAEQ. For the future, PNAEQ and the Working Group will work on the continuous update of the tools content distributed in each survey according to international references and the experience of other EQA organizers.N/

A comparison of various quasi-newton schemes for partitioned fluid-structure interaction

During the last 5 years, quasi-Newton schemes have proven to be a robust and efficient way to couple partitioned fluid-structure interaction. We showed in previous work that they also allow to perform a parallel coupling. Bogaers et al. introduced a new variant based on a multi-vector update [14]. This variant renders a tuning of the reuse of old information unnecessary as all old iterations are implicitly covered in a Jacobian update. In this work, we compare this multi-vector variant in an inverse formulation to the classical IQN-ILS algorithm for serial as well as parallel coupling

Secure Federated Learning against Model Poisoning Attacks via Client Filtering

Given the distributed nature, detecting and defending against the backdoor attack under federated learning (FL) systems is challenging. In this paper, we observe that the cosine similarity of the last layer's weight between the global model and each local update could be used effectively as an indicator of malicious model updates. Therefore, we propose CosDefense, a cosine-similarity-based attacker detection algorithm. Specifically, under CosDefense, the server calculates the cosine similarity score of the last layer's weight between the global model and each client update, labels malicious clients whose score is much higher than the average, and filters them out of the model aggregation in each round. Compared to existing defense schemes, CosDefense does not require any extra information besides the received model updates to operate and is compatible with client sampling. Experiment results on three real-world datasets demonstrate that CosDefense could provide robust performance under the state-of-the-art FL poisoning attack

Automatised full one-loop renormalisation of the MSSM I: The Higgs sector, the issue of tan(beta) and gauge invariance

We give an extensive description of the renormalisation of the Higgs sector of the minimal supersymmetric model in SloopS. SloopS is an automatised code for the computation of one-loop processes in the MSSM. In this paper, the first in a series, we study in detail the non gauge invariance of some definitions of tan(beta). We rely on a general non-linear gauge fixing constraint to make the gauge parameter dependence of different schemes for tan(beta) at one-loop explicit. In so doing, we update, within these general gauges, an important Ward-Slavnov-Taylor identity on the mixing between the pseudo-scalar Higgs, A^0, and the Z^0. We then compare the tan(beta) scheme dependence of a few observables. We find that the best tan(beta) scheme is the one based on the decay A^0 -> tau^+ tau^- because of its gauge invariance, being unambiguously defined from a physical observable, and because it is numerically stable. The oft used DRbar scheme performs almost as well on the last count, but is usually defined from non-gauge invariant quantities in the Higgs sector. The use of the heavier scalar Higgs mass in lieu of tan(beta) though related to a physical parameter induces too large radiative corrections in many instances and is therefore not recommended.Comment: 34 pages, 1 figure, typos corrected, accepted for publication in Phys. Rev.

Asymmetric contrarians in opinion dynamics

Asymmetry in contrarian behavior is investigated within the Galam model of opinion dynamics using update groups of size 3 with two competing opinions A and B. Denoting $x$ and $y$ the respective proportions of A and B contrarians, four schemes of implementations are studied. First scheme activates contrarians after each series of updates with probabilities $x$ and $y$ for agents holding respectively opinion A and B. Second scheme activates contrarians within the update groups only against global majority with probability $x$ when A is majority and $y$ when B is majority. Third scheme considers in-group contrarians acting prior to the local majority update against both local majority and minority opinions. Last scheme activates in-group contrarians prior to the local majority update but only against the local majority. The main result is the loss of the fifty-fifty attractor produced by symmetric contrarians. Producing a bit less contrarians on its own side than the other side becomes the key to win a public debate, which in turn can guarantee an election victory. The associated phase diagram of opinion dynamics is found to exhibit a rich variety of counterintuitive results.Comment: 13 pages LaTeX with numerous figs; ver 2 updated with new bibliographic refeernces and corrections to figure reference

Forward Private Searchable Symmetric Encryption with Optimized I/O Efficiency

Recently, several practical attacks raised serious concerns over the security of searchable encryption. The attacks have brought emphasis on forward privacy, which is the key concept behind solutions to the adaptive leakage-exploiting attacks, and will very likely to become mandatory in the design of new searchable encryption schemes. For a long time, forward privacy implies inefficiency and thus most existing searchable encryption schemes do not support it. Very recently, Bost (CCS 2016) showed that forward privacy can be obtained without inducing a large communication overhead. However, Bost's scheme is constructed with a relatively inefficient public key cryptographic primitive, and has a poor I/O performance. Both of the deficiencies significantly hinder the practical efficiency of the scheme, and prevent it from scaling to large data settings. To address the problems, we first present FAST, which achieves forward privacy and the same communication efficiency as Bost's scheme, but uses only symmetric cryptographic primitives. We then present FASTIO, which retains all good properties of FAST, and further improves I/O efficiency. We implemented the two schemes and compared their performance with Bost's scheme. The experiment results show that both our schemes are highly efficient, and FASTIO achieves a much better scalability due to its optimized I/O