Focus group discussions.

This chapter provides an overview of focus group discussions as a research method. Using illustrative examples, the chapter discusses the appropriateness of the technique for accounting research. The chapter then highlights both the strengths and drawbacks of the technique and provides guidance on how to mitigate the drawbacks. The chapter concludes with advice on the practical considerations for running focus group discussions and articulates the unique data analysis considerations of the technique

An Isogeny-Based Adaptor Signature Using SQISign

Transactions on blockchains can prove very costly, so as a solution to avoid these large costs, schemes involving payment channel networks have been developed. One approach to implementing these off-chain forms of payment securely involves adaptor signatures. Previous work has established a generic construction of adaptor signatures using signature schemes that satisfy a couple of key properties. Unfortunately, most post-quantum signature schemes do not satisfy these properties, meaning more work needs to be done to develop quantum-safe solutions. We introduce a new post-quantum adaptor signature that uses SQISign as its underlying signature. SQISign has been shown to be significantly faster and to require less storage than any other isogeny-based signature, giving our construction potential for significant improvements in the way of efficiency. We give the details of the new scheme, provide proofs of its security, and estimate memory costs

Fast and Frobenius: Rational Isogeny Evaluation over Finite Fields

Consider the problem of efficiently evaluating isogenies $\phi: E \to E/H$ of elliptic curves over a finite field $\mathbb{F}_q$, where the kernel $H = \langle G\rangle$ is a cyclic group of odd (prime) order: given $E$, $G$, and a point (or several points) $P$ on $E$, we want to compute $\phi(P)$. This problem is at the heart of efficient implementations of group-action- and isogeny-based post-quantum cryptosystems such as CSIDH. Algorithms based on V{\'e}lu's formulae give an efficient solution to this problem when the kernel generator $G$ is defined over $\mathbb{F}_q$. However, for general isogenies, $G$ is only defined over some extension $\mathbb{F}_{q^k}$, even though $\langle G\rangle$ as a whole (and thus $\phi$) is defined over the base field $\mathbb{F}_q$; and the performance of V{\'e}lu-style algorithms degrades rapidly as $k$ grows. In this article we revisit the isogeny-evaluation problem with a special focus on the case where $1 \le k \le 12$. We improve V{\'e}lu-style isogeny evaluation for many cases where $k = 1$ using special addition chains, and combine this with the action of Galois to give greater improvements when $k > 1$

Should you use steroids to treat infectious mononucleosis?

Studies of steroids to treat infectious mononucleosis have found no significant effect on the clinical course of the illness at 1 to 3 months (strength of recommendation [SOR]: B, 1 randomized controlled trial [RCT] and 1 nonrandomized double-blind trial). Although steroids have been shown to improve resolution of hematologic ab- normalities, fever, and white blood cell count, and may shorten length of infirmary stay (SOR: B, 1 nonrandomized double-blind trial and 1 RCT), no significant difference was found in resolution of symptoms with or without steroids (SOR: A, 2 RCTs)

Efficient supersingularity testing over F_p and CSIDH key validation

International audienceMany public-key cryptographic protocols, notably non-interactive key exchange (NIKE), require incoming public keys to be validated to mitigate some adaptive attacks. In CSIDH, an isogeny-based post-quantum NIKE, a key is deemed legitimate if the given Montgomery coefficient specifies a supersingular elliptic curve over the prime field. In this work, we survey the current supersingularity tests used for CSIDH key validation, and implement and measure two new alternative algorithms. Our implementation shows that we can determine supersingularity substantially faster, and using less memory, than the state-of-the-art

Solving the Tensor Isomorphism Problem for special orbits with low rank points: Cryptanalysis and repair of an Asiacrypt 2023 commitment scheme

The Tensor Isomorphism Problem (TIP) has been shown to be equivalent to the matrix code equivalence problem, making it an interesting candidate on which to build post-quantum cryptographic primitives. These hard problems have already been used in protocol development. One of these, MEDS, is currently in Round 1 of NIST\u27s call for additional post-quantum digital signatures. In this work, we consider the TIP for a special class of tensors. The hardness of the decisional version of this problem is the foundation of a commitment scheme proposed by D\u27Alconzo, Flamini, and Gangemi (Asiacrypt 2023). We present polynomial-time algorithms for the decisional and computational versions of TIP for special orbits, which implies that the commitment scheme is not secure. The key observations of these algorithms are that these special tensors contain some low-rank points, and their stabilizer groups are not trivial. With these new developments in the security of TIP in mind, we give a new commitment scheme based on the general TIP that is non-interactive, post-quantum, and statistically binding, making no new assumptions. Such a commitment scheme does not currently exist in the literature

Fast and Frobenius: Rational Isogeny Evaluation over Finite Fields

Consider the problem of efficiently evaluating isogenies $\phi: \mathcal{E} \to \mathcal{E}/H$ of elliptic curves over a finite field $\mathbb{F}_q$, where the kernel $H = \langle{G}\rangle$ is a cyclic group of odd (prime) order: given $\mathcal{E}$, $G$, and a point (or several points) $P$ on $\mathcal{E}$, we want to compute $\phi(P)$. This problem is at the heart of efficient implementations of group-action- and isogeny-based post-quantum cryptosystems such as CSIDH. Algorithms based on Vélu\u27s formul\ae{} give an efficient solution to this problem when the kernel generator $G$ is defined over $\mathbb{F}_q$. However, for general isogenies, $G$ is only defined over some extension $\mathbb{F}_{q^k}$, even though $\langle{G}\rangle$ as a whole (and thus $\phi$) is defined over the base field $\mathbb{F}_q$; and the performance of Vélu-style algorithms degrades rapidly as $k$ grows. In this article, we revisit the isogeny-evaluation problem with a special focus on the case where $1 \le k \le 12$. We improve Vélu-style isogeny evaluation for many cases where $k = 1$ using special addition chains, and combine this with the action of Galois to give greater improvements when $k > 1$

Seeing Community for the Trees: The Links among Contact with Natural Environments, Community Cohesion, and Crime

Individuals may be losing touch with nature as their contact with it decreases worldwide. Although the consequences for people's personal well-being outcomes are becoming well documented, there is almost no research examining the social correlates of contact with nature. This article used a large nationally representative sample to link objective (percent greenspace) and subjective measurements of contact with nature, community cohesion, and local crime incidence. The perceived quality, views, and amount of time spent in nature were linked to more community cohesion, and in turn, the perception of cohesive communities enhanced individual well-being outcomes and contributions back to society through higher workplace productivity and environmentally responsible behaviors. Our findings also indicated that local nature was linked to lower crime both directly and indirectly through its effects on community cohesion

Post-intervention Status in Patients With Refractory Myasthenia Gravis Treated With Eculizumab During REGAIN and Its Open-Label Extension

OBJECTIVE: To evaluate whether eculizumab helps patients with anti-acetylcholine receptor-positive (AChR+) refractory generalized myasthenia gravis (gMG) achieve the Myasthenia Gravis Foundation of America (MGFA) post-intervention status of minimal manifestations (MM), we assessed patients' status throughout REGAIN (Safety and Efficacy of Eculizumab in AChR+ Refractory Generalized Myasthenia Gravis) and its open-label extension. METHODS: Patients who completed the REGAIN randomized controlled trial and continued into the open-label extension were included in this tertiary endpoint analysis. Patients were assessed for the MGFA post-intervention status of improved, unchanged, worse, MM, and pharmacologic remission at defined time points during REGAIN and through week 130 of the open-label study. RESULTS: A total of 117 patients completed REGAIN and continued into the open-label study (eculizumab/eculizumab: 56; placebo/eculizumab: 61). At week 26 of REGAIN, more eculizumab-treated patients than placebo-treated patients achieved a status of improved (60.7% vs 41.7%) or MM (25.0% vs 13.3%; common OR: 2.3; 95% CI: 1.1-4.5). After 130 weeks of eculizumab treatment, 88.0% of patients achieved improved status and 57.3% of patients achieved MM status. The safety profile of eculizumab was consistent with its known profile and no new safety signals were detected. CONCLUSION: Eculizumab led to rapid and sustained achievement of MM in patients with AChR+ refractory gMG. These findings support the use of eculizumab in this previously difficult-to-treat patient population. CLINICALTRIALSGOV IDENTIFIER: REGAIN, NCT01997229; REGAIN open-label extension, NCT02301624. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that, after 26 weeks of eculizumab treatment, 25.0% of adults with AChR+ refractory gMG achieved MM, compared with 13.3% who received placebo

Minimal Symptom Expression' in Patients With Acetylcholine Receptor Antibody-Positive Refractory Generalized Myasthenia Gravis Treated With Eculizumab

The efficacy and tolerability of eculizumab were assessed in REGAIN, a 26-week, phase 3, randomized, double-blind, placebo-controlled study in anti-acetylcholine receptor antibody-positive (AChR+) refractory generalized myasthenia gravis (gMG), and its open-label extension