Thermal depinning of fluxons in ratchet discrete Josephson rings

We study numerically the thermal depinning of single fluxons in ratchet Josephson junction rings. Rings are made of 9 junctions with 3 different critical currents. We present results for a wide range of the main physical parameters of the system: damping, coupling and temperature. The computed results can be well understood in the framework of single particle thermal activation theories

Key Management for Onion Routing in a True Peer to Peer Setting

Onion routing is a technique for anonymous and privacy preserving communication at the base of popular Internet anonymity tools such as Tor. In onion routing, traffic is relayed by a number of intermediary nodes (called relays) before it reaches the intended destination. To guarantee privacy and prevent tampering, each packet is encrypted multiple times in a layered manner, using the public keys of the relays. Therefore, this mechanism makes two important assumptions: first, that the relays are able to communicate with each other; second, that the user knows the list of available relays and their respective public keys. Tor implements therefore a distributed directory listing the relays and their keys. When a user is not able to communicate with relays directly, he has to use special bridge servers to connect to the onion network. This construction, however, does not work in a fully peer to peer setting, where each peer only knows a limited number of other peers and may not be able to communicate with some of them due, for instance, to NAT or firewalls. In this paper we propose a key management scheme for onion routing that overcomes these problems. The proposed solution does not need a directory system and does not imply knowledge of all active relays, while it guarantees the secure distribution of public keys. We also present an alternative strategy for building circuit of relays based on bloom filters. The proposed construction overcomes some of the structural inefficiencies of the Tor design, and opens the way for implementing onion routing over a true peer to peer overlay network

On acceptance conditions for membrane systems: characterisations of L and NL

In this paper we investigate the affect of various acceptance conditions on recogniser membrane systems without dissolution. We demonstrate that two particular acceptance conditions (one easier to program, the other easier to prove correctness) both characterise the same complexity class, NL. We also find that by restricting the acceptance conditions we obtain a characterisation of L. We obtain these results by investigating the connectivity properties of dependency graphs that model membrane system computations

Increased markers of cardiac vagal activity in leucine-rich repeat kinase 2-associated Parkinson's disease.

PurposeCardiac autonomic dysfunction manifests as reduced heart rate variability (HRV) in idiopathic Parkinson's disease (PD), but no significant reduction has been found in PD patients who carry the LRRK2 mutation. Novel HRV features have not been investigated in these individuals. We aimed to assess cardiac autonomic modulation through standard and novel approaches to HRV analysis in individuals who carry the LRRK2 G2019S mutation.MethodsShort-term electrocardiograms were recorded in 14 LRRK2-associated PD patients, 25 LRRK2-non-manifesting carriers, 32 related non-carriers, 20 idiopathic PD patients, and 27 healthy controls. HRV measures were compared using regression modeling, controlling for age, sex, mean heart rate, and disease duration. Discriminant analysis highlighted the feature combination that best distinguished LRRK2-associated PD from controls.ResultsBeat-to-beat and global HRV measures were significantly increased in LRRK2-associated PD patients compared with controls (e.g., deceleration capacity of heart rate: p = 0.006) and idiopathic PD patients (e.g., 8th standardized moment of the interbeat interval distribution: p = 0.0003), respectively. LRRK2-associated PD patients also showed significantly increased irregularity of heart rate dynamics, as quantified by Rényi entropy, when compared with controls (p = 0.002) and idiopathic PD patients (p = 0.0004). Ordinal pattern statistics permitted the identification of LRRK2-associated PD individuals with 93% sensitivity and 93% specificity. Consistent results were found in a subgroup of LRRK2-non-manifesting carriers when compared with controls.ConclusionsIncreased beat-to-beat HRV in LRRK2 G2019S mutation carriers compared with controls and idiopathic PD patients may indicate augmented cardiac autonomic cholinergic activity, suggesting early impairment of central vagal feedback loops in LRRK2-associated PD

Thermal depinning of fluxons in discrete Josephson rings

We study the thermal depinning of single fluxons in rings made of Josephson junctions. Due to thermal fluctuations a fluxon can be excited from its energy minima and move through the array, causing a voltage across each junction. We find that for the initial depinning, the fluxon behaves as a single particle and follows a Kramers-type escape law. However, under some conditions this single particle description breaks down. At low values of the discreteness parameter and low values of the damping, the depinning rate is larger than the single particle result would suggest. In addition, for some values of the parameters the fluxon can undergo low-voltage diffusion before switching to the high-voltage whirling mode. This type of diffusion is similar to phase diffusion in a single junction, but occurs without frequency-dependent damping. We study the switching to the whirling state as well

Disertaciones sobre la fundamentación de las decisiones constitucionales

El presente artículo analiza desde el modelo hermenéutico, nuevas maneras de comprenderlos derechos fundamentales, donde la práctica judicial adquiere especial relevancia, y además se enriquece de metodologías interpretativas como el sistema del precedente, introducción de los test constitucionales y las aplicaciones de las técnicas de ponderación y proporcionalidad. De este modo, el Derecho constitucional, integra una nueva teoría de textos normativos que abandona la rígida distinción entre fuentes primarias y secundarias por encontrarla insuficiente para resolverla variedad y complejidad de problemas jurídicos actuales. Por tanto, a través de un ejemplo de jurisprudencia acerca del matrimonio igualitario de la Corte Constitucional Colombiana, se demostrará los diferentes avances en esta materia.Palabras clave: Argumentación jurídica, neoconstitucionalismo, reglas interpretativas, Corte Constitucional de Colombia, decisión judicial.AbstractThis article analyzes, from the hermeneutic model, new ways of understanding fundamental rights, where the judicial practice is especially relevant and gets further enriched through interpretive methodologies such as the precedent system, the introduction of constitutional tests and the application of techniques of balancing and proportionality. In this way, constitutional law includes a new theory of legal texts, which abandons the rigid distinction between primary and secondary sources for finding it insufficient to resolve the variety and complexity of current legal problems. Accordingly, we will show the different advances made in this area through an example of equal marriage law in the Constitutional Court of Colombia.Keywords: Legal argumentation, neoconstitutionalism, interpretive rules, Constitutional Court of Colombia, judicial decision.</p

Decaying lava extrusion rate at El Reventador Volcano, Ecuador measured using high-resolution satellite radar

Lava extrusion at erupting volcanoes causes rapid changes in topography and morphology on the order of tens or even hundreds of metres. Satellite radar provides a method for measuring changes in topographic height over a given time period to an accuracy of metres, either by measuring the width of radar shadow cast by steep sided features, or by measuring the difference in radar phase between two sensors separated in space. We measure height changes, and hence estimate extruded lava volume flux, at El Reventador, Ecuador between 2011 and 2016, using data from the Radarsat-2 and TanDEM-X satellite missions. We find 39 new lava flows were extruded between 9 February 2012 and 24 August 2016, with a cumulative volume of 44.8M m3 dense rock equivalent and a gradually decreasing eruption rate. The average dense rock rate of lava extrusion during this time is 0.31 ± 0.02 m3s−1, which is similar to the long term average from 1972 to 2016. Apart from a volumetrically small dyke opening event between 9 March and 10 June 2012, lava extrusion at El Reventador is not accompanied by any significant magmatic ground deformation. We use a simple physics-based model to estimate that the volume of the magma reservoir under El Reventador is greater than 3 km3. Our lava extrusion data can be equally well fit by models representing a closed reservoir depressurising during the eruption with no magma recharge, or an open reservoir with a time-constant magma recharge rate of up to 0.35 ± 0.01 m3s−