Physical Simulation of Inarticulate Robots

In this note we study the structure and the behavior of inarticulate robots. We introduce a robot that moves by successive revolvings. The robot's structure is analyzed, simulated and discussed in detail

Satisfiability of General Intruder Constraints with and without a Set Constructor

Many decision problems on security protocols can be reduced to solving so-called intruder constraints in Dolev Yao model. Most constraint solving procedures for protocol security rely on two properties of constraint systems called monotonicity and variable origination. In this work we relax these restrictions by giving a decision procedure for solving general intruder constraints (that do not have these properties) that stays in NP. Our result extends a first work by L. Mazar\'e in several directions: we allow non-atomic keys, and an associative, commutative and idempotent symbol (for modeling sets). We also discuss several new applications of the results.Comment: Submitted to the Special issue of Information and Computation on Security and Rewriting Techniques (SecReT), 2011. 59 page

Intruder deducibility constraints with negation. Decidability and application to secured service compositions

The problem of finding a mediator to compose secured services has been reduced in our former work to the problem of solving deducibility constraints similar to those employed for cryptographic protocol analysis. We extend in this paper the mediator synthesis procedure by a construction for expressing that some data is not accessible to the mediator. Then we give a decision procedure for verifying that a mediator satisfying this non-disclosure policy can be effectively synthesized. This procedure has been implemented in CL-AtSe, our protocol analysis tool. The procedure extends constraint solving for cryptographic protocol analysis in a significative way as it is able to handle negative deducibility constraints without restriction. In particular it applies to all subterm convergent theories and therefore covers several interesting theories in formal security analysis including encryption, hashing, signature and pairing.Comment: (2012

Constraints-based Verification of Parameterized Cryptographic Protocols.

Cryptographic protocols are crucial for securing electronic transactions. The confidence in these protocols can be increased by the formal analysis of their security properties. Although many works have been dedicated to standard protocols like Needham-Schroeder very few address the more challenging class of group protocols. We present a synchronous model for group protocols, that generalizes standard protocol models by permitting unbounded lists inside messages. In this extended model we propose a correct and complete set of inference rules for checking security properties in presence of an active intruder for the class of Well-Tagged protocols. We prove that the application of these rules on a constraint system terminates and that the normal form obtained can be checked for satisfiability. Therefore, we present here a decision procedure for this class

A Note On Computing Set Overlap Classes

Let ${\cal V}$ be a finite set of $n$ elements and ${\cal F}=\{X_1,X_2, >..., X_m\}$ a family of $m$ subsets of ${\cal V}.$ Two sets $X_i$ and $X_j$ of ${\cal F}$ overlap if $X_i \cap X_j \neq \emptyset,$ $X_j \setminus X_i \neq \emptyset,$ and $X_i \setminus X_j \neq \emptyset.$ Two sets $X,Y\in {\cal F}$ are in the same overlap class if there is a series $X=X_1,X_2, ..., X_k=Y$ of sets of ${\cal F}$ in which each $X_iX_{i+1}$ overlaps. In this note, we focus on efficiently identifying all overlap classes in $O(n+\sum_{i=1}^m |X_i|)$ time. We thus revisit the clever algorithm of Dahlhaus of which we give a clear presentation and that we simplify to make it practical and implementable in its real worst case complexity. An useful variant of Dahlhaus's approach is also explained

Microwave photon generation in a doubly tunable superconducting resonator

We have developed and tested a doubly tunable resonator, with the intention to simulate fast motion of the resonator boundaries in real space. Our device is a superconducting coplanar-waveguide half-wavelength microwave resonator, with fundamental resonant frequency ~5 GHz. Both of its ends are terminated by dc-SQUIDs, which serve as magnetic-flux-controlled inductances. Applying a flux to either SQUID allows tuning of the resonant frequency by approximately 700 MHz. By using two separate on-chip magnetic-flux lines, we modulate the SQUIDs with two tones of equal frequency, close to twice that of the resonator's fundamental mode. We observe photon generation, at the fundamental frequency, above a certain pump amplitude threshold. By varying the relative phase of the two pumps we are able to control the photon generation threshold, in good agreement with a theoretical model for the modulation of the boundary conditions. At the same time, some of our observations deviate from the theoretical predictions, which we attribute to parasitic couplings, resulting in current driving of the SQUIDs.Comment: 7 pages, 4 figure

Is COVID-19 perceived as a threat to equal career opportunities amongst Swiss medical students? A cross-sectional survey study from Bern and Geneva.

INTRODUCTION Students frequently rely on part-time jobs to earn a living wage. We sought to evaluate the sociodemographic status of Swiss medical students and their perception regarding equal career opportunities in view of impaired part-time job opportunities under the COVID-19 pandemic. METHODS We conducted an anonymous online survey among Swiss medical students from Bern and Geneva over a period of 4 months between December 2020 and April 2021. We evaluated sociodemographic data, current living situation, part-time job occupation as well as other sources of income to fund living expenses, and, by means of a five-point Likert scale (1=strongly disagree and 5=strongly agree), whether COVID-19 was perceived as impeding equal career opportunities. RESULTS Of 968 participants, corresponding to around 13.8% of all medical students in Switzerland, 81.3% had part-time jobs. Amongst the employed, 54.8% worked to afford living expenses and 28.9% reported a negative financial impact due to reduced part-time jobs under the pandemic. The loss of part-time jobs was perceived to make medical studies a privilege for students with higher socioeconomic status (4.11±1.0), whose opportunity to study is independent of a regular income. A governmental backup plan was considered crucial to support affected students (4.22±0.91). DISCUSSION COVID-19 and its sequelae are perceived as a threat for Swiss medical students and lead to a disadvantage for those with lower socioeconomic status. Nationwide measures should be established to foster equal career opportunities

Does turbulence affect the habitat choice of Atlantic salmon parr?

Habitat preferences of Atlantic salmon parr are commonly described using mean flow velocity, water depth, and substrate as habitat variables, and a variety of habitat models have been developed using these variables to predict habitat quality. However, Atlantic salmon parr live in highly turbulent streams and rivers, in which intense fluctuations of flow velocity occur. Habitat preferences that consider the high variability of flow velocity have not been studied, and this although it has been shown in laboratory experiments that turbulence may affect the behavior and energetics of fish. Consequently, we studied the use of turbulent flow by Atlantic salmon parr in Patapédia River, Québec, Canada using radio-telemetry. We analyzed summer habitat preferences of individual parr in relation to several dynamic hydraulic variables such as standard deviation of flow velocity, turbulent kinetic energy, Froude number, and shear stress, and compared them with the habitat availability within the river reach. Our results revealed that in a natural flow environment, parr display a high individual variability in habitat preferences in relation to flow turbulence. Such heterogeneous habitat preferences suggest that individuals are not constrained to single habitat types and exhibit flexible habitat use. Furthermore, no differences were observed in habitat preferences between the four daily periods (dawn, day, dusk, and night) within individual parr

Cool-SPS: Pulling down the temperature, pushing up the reactivity

The use of materials, especially in the field of electronics, but also for catalysis, health (…), requires the control of their shaping (dense or porous materials, spherical or anisotropic particles…). This objective is frequently reached through the preparation of ceramics by conventional, high temperature sintering. Spark Plasma Sintering (SPS) is a particularly efficient densification method, initially dedicated to refractory materials, that is now extremely versatile and allows for the elaboration of nanostructured and/or transparent ceramics, among many other applications. Please click Additional Files below to see the full abstract