99 research outputs found
Automated Reasoning over Deontic Action Logics with Finite Vocabularies
In this paper we investigate further the tableaux system for a deontic action
logic we presented in previous work. This tableaux system uses atoms (of a
given boolean algebra of action terms) as labels of formulae, this allows us to
embrace parallel execution of actions and action complement, two action
operators that may present difficulties in their treatment. One of the
restrictions of this logic is that it uses vocabularies with a finite number of
actions. In this article we prove that this restriction does not affect the
coherence of the deduction system; in other words, we prove that the system is
complete with respect to language extension. We also study the computational
complexity of this extended deductive framework and we prove that the
complexity of this system is in PSPACE, which is an improvement with respect to
related systems.Comment: In Proceedings LAFM 2013, arXiv:1401.056
Eine präzise Multilevel-Testbench zur Systemsimulation und Charakterisierung einer 2,5 GHz PLL
In diesem Aufsatz wird eine präzise Multilevel-Testbench zur PLL-Charakterisierung vorgestellt. Die Schwerpunkte dieses Beitrags sind einerseits das 10 GHz VCO-Design und andererseits die vorhersagefähigen Ergebnisse der mit Hilfe dieses Multilevelansatzes durchgeführten PLL-Systemsimulationen. <br><br> Bei dem VCO-Design wurden folgende Ergebnisse erreicht: Abstimmbereich &asymp;26% bzw. kvco&asymp;1300 MHz/V, Phasenrauschen PN=&ndash;101,4 dBc/Hz @1 MHz Offset vom 10 GHz Träger, Leistungsverbrauch = 5,5 mW. Als realistisches Demonstrationsbeispiel ist das &#0132;analog mixed signal&#0147;-Verhalten eines 2,5 GHz PLL-Systems für &#0132;dual-conversion&#0147;-Strukturen bei IEEE 802.11a WLAN-Anwendungen gewählt worden. Für dieses Beispiel wird eine effiziente PLL-Modellierung kritischer PLL-Blöcke (Frequenzteiler und Phasenfrequenzdetektor) auf der Basis der PSS-Analyse und neuer Verilog-A/MS Befehle demonstriert. Die dabei verwendete Testbench kann im Prinzip in verschiedenen aktuellen Wireless Kommunikationssystemen bis 10 GHz wieder verwendet werden (Reuse-IP). Dieser Ansatz führt einerseits zur Verbesserung der Simulationszeiten (verglichen mit dem Transistorlevel) und andererseits zu genaueren und realistischeren Ergebnissen, vor allem am VCO-Ausgang (verglichen mit dem HDL-Level)
On the construction of explosive relation algebras
Fork algebras are an extension of relation algebras obtained by extending the
set of logical symbols with a binary operator called fork. This class of
algebras was introduced by Haeberer and Veloso in the early 90's aiming at
enriching relation algebra, an already successful language for program
specification, with the capability of expressing some form of parallel
computation.
The further study of this class of algebras led to many meaningful results
linked to interesting properties of relation algebras such as representability
and finite axiomatizability, among others. Also in the 90's, Veloso introduced
a subclass of relation algebras that are expansible to fork algebras, admitting
a large number of non-isomorphic expansions, referred to as explosive relation
algebras.
In this work we discuss some general techniques for constructing algebras of
this type
A Logic for Real-Time Systems Specification, Its Algebraic Semantics, and Equational Calculus
We present a logic for real time systems specification which is an extension of first order dynamic logic by adding (a) arbitrary atomic actions rather than only assignments, (b) variables over actions which allow to specify systems partially, and (c) explicit time. The logic is algebraized using closure fork algebras and a representation theorem for this class is presented. This allows to define an equational (but infinitary) proof system for the algebraization.Laboratorio de Investigación y Formación en Informática Avanzad
Geometrical dependence of low frequency noise in superconducting flux qubits
A general method for directly measuring the low-frequency flux noise (below
10 Hz) in compound Josephson junction superconducting flux qubits has been used
to study a series of 85 devices of varying design. The variation in flux noise
across sets of qubits with identical designs was observed to be small. However,
the levels of flux noise systematically varied between qubit designs with
strong dependence upon qubit wiring length and wiring width. Furthermore,
qubits fabricated above a superconducting ground plane yielded lower noise than
qubits without such a layer. These results support the hypothesis that
localized magnetic impurities in the vicinity of the qubit wiring are a key
source of low frequency flux noise in superconducting devices.Comment: 5 pages, 5 figure
Single-charge escape processes through a hybrid turnstile in a dissipative environment
We have investigated the static, charge-trapping properties of a hybrid
superconductor---normal metal electron turnstile embedded into a high-ohmic
environment. The device includes a local Cr resistor on one side of the
turnstile, and a superconducting trapping island on the other side. The
electron hold times, t ~ 2-20s, in our two-junction circuit are comparable with
those of typical multi-junction, N >= 4, normal-metal single-electron tunneling
devices. A semi-phenomenological model of the environmental activation of
tunneling is applied for the analysis of the switching statistics. The
experimental results are promising for electrical metrology.Comment: Submitted to New Journal of Physics 201
Understanding the Concentration Dependence of Viral Capsid Assembly Kinetics - the Origin of the Lag Time and Identifying the Critical Nucleus Size
The kinetics for the assembly of viral proteins into a population of capsids
can be measured in vitro with size exclusion chromatography or dynamic light
scattering, but extracting mechanistic information from these studies is
challenging. For example, it is not straightforward to determine the critical
nucleus size or the elongation time (the time required for a nucleated partial
capsid to grow completion). We show that, for two theoretical models of capsid
assembly, the critical nucleus size can be determined from the concentration
dependence of the assembly reaction half-life and the elongation time is
revealed by the length of the lag phase. Furthermore, we find that the system
becomes kinetically trapped when nucleation becomes fast compared to
elongation. Implications of this constraint for determining elongation
mechanisms from experimental assembly data are discussed.Comment: Submitted to Biophysical Journa
Dynamic Pathways for Viral Capsid Assembly
We develop a class of models with which we simulate the assembly of particles
into T1 capsid-like objects using Newtonian dynamics. By simulating assembly
for many different values of system parameters, we vary the forces that drive
assembly. For some ranges of parameters, assembly is facile, while for others,
assembly is dynamically frustrated by kinetic traps corresponding to malformed
or incompletely formed capsids. Our simulations sample many independent
trajectories at various capsomer concentrations, allowing for statistically
meaningful conclusions. Depending on subunit (i.e., capsomer) geometries,
successful assembly proceeds by several mechanisms involving binding of
intermediates of various sizes. We discuss the relationship between these
mechanisms and experimental evaluations of capsid assembly processes.Comment: 13 pages, 13 figures. Submitted to Biophys.
Long-term effects of tongue piercing — a case control study
The aim of this study was to evaluate tooth and periodontal damage in subjects wearing a tongue piercing (TP) in comparison to matched control subjects without tongue piercing. Members of the German Federal Armed Forces who had TP (group TP) and a matched control group (group C) volunteered to take part in the study. The time in situ, localization and material of TP were documented. Dental examinations included DMF-T, oral hygiene, enamel fissures (EF), enamel cracks (EC) and recessions. Statistical analysis was determined by χ2 test and the t test. Both groups had 46 male subjects (mean age 22.1 years). The piercings had been in situ for 3.8 ± 3.1 years. Subjects in the TP group had a total of 1,260 teeth. Twenty-nine subjects had 115 teeth (9.1%) with EF (67% lingual). In group C (1,243 teeth), 30 subjects had 60 teeth with EF (4.8%, 78% vestibular) (p < 0.01). Thirty-eight subjects belonging to group TP had EC in 186 teeth (15%). In group C, 26 subjects with 56 teeth (4.5%) were affected by EC (p < 0.001). Twenty-seven subjects in group TP had 97 teeth (7.7%) with recessions. Lingual surfaces of anterior teeth in the lower jaw were affected most frequently (74%). In group C, 8 subjects had 19 teeth (1.5%) with recessions (65% vestibular). Differences between the two groups were statistically significant (p < 0.001). Tongue piercing is correlated with an increased occurrence of enamel fissures, enamel cracks and lingual recessions. Patients need better information on the potential complications associated with tongue piercing
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