5,547 research outputs found
Parameterized Model-Checking for Timed-Systems with Conjunctive Guards (Extended Version)
In this work we extend the Emerson and Kahlon's cutoff theorems for process
skeletons with conjunctive guards to Parameterized Networks of Timed Automata,
i.e. systems obtained by an \emph{apriori} unknown number of Timed Automata
instantiated from a finite set of Timed Automata templates.
In this way we aim at giving a tool to universally verify software systems
where an unknown number of software components (i.e. processes) interact with
continuous time temporal constraints. It is often the case, indeed, that
distributed algorithms show an heterogeneous nature, combining dynamic aspects
with real-time aspects. In the paper we will also show how to model check a
protocol that uses special variables storing identifiers of the participating
processes (i.e. PIDs) in Timed Automata with conjunctive guards. This is
non-trivial, since solutions to the parameterized verification problem often
relies on the processes to be symmetric, i.e. indistinguishable. On the other
side, many popular distributed algorithms make use of PIDs and thus cannot
directly apply those solutions
Randomized benchmarking of single and multi-qubit control in liquid-state NMR quantum information processing
Being able to quantify the level of coherent control in a proposed device
implementing a quantum information processor (QIP) is an important task for
both comparing different devices and assessing a device's prospects with
regards to achieving fault-tolerant quantum control. We implement in a
liquid-state nuclear magnetic resonance QIP the randomized benchmarking
protocol presented by Knill et al (PRA 77: 012307 (2008)). We report an error
per randomized pulse of with a
single qubit QIP and show an experimentally relevant error model where the
randomized benchmarking gives a signature fidelity decay which is not possible
to interpret as a single error per gate. We explore and experimentally
investigate multi-qubit extensions of this protocol and report an average error
rate for one and two qubit gates of for a three
qubit QIP. We estimate that these error rates are still not decoherence limited
and thus can be improved with modifications to the control hardware and
software.Comment: 10 pages, 6 figures, submitted versio
Computed microtomography visualization and quantification of mouse ischemic brain lesion by nonionic radio contrast agents.
AIM:
To explore the possibility of brain imaging by microcomputed tomography (microCT) using x-ray contrasting methods to visualize mouse brain ischemic lesions after middle cerebral artery occlusion (MCAO). ----- METHODS:
Isolated brains were immersed in ionic or nonionic radio contrast agent (RCA) for 5 days and subsequently scanned using microCT scanner. To verify whether ex-vivo microCT brain images can be used to characterize ischemic lesions, they were compared to Nissl stained serial histological sections of the same brains. To verify if brains immersed in RCA may be used afterwards for other methods, subsequent immunofluorescent labeling with anti-NeuN was performed. ----- RESULTS:
Nonionic RCA showed better gray to white matter contrast in the brain, and therefore was selected for further studies. MicroCT measurement of ischemic lesion size and cerebral edema significantly correlated with the values determined by Nissl staining (ischemic lesion size: P=0.0005; cerebral edema: P=0.0002). Brain immersion in nonionic RCA did not affect subsequent immunofluorescent analysis and NeuN immunoreactivity. ----- CONCLUSION:
MicroCT method was proven to be suitable for delineation of the ischemic lesion from the non-infarcted tissue, and quantification of lesion volume and cerebral edema
Using Flow Specifications of Parameterized Cache Coherence Protocols for Verifying Deadlock Freedom
We consider the problem of verifying deadlock freedom for symmetric cache
coherence protocols. In particular, we focus on a specific form of deadlock
which is useful for the cache coherence protocol domain and consistent with the
internal definition of deadlock in the Murphi model checker: we refer to this
deadlock as a system- wide deadlock (s-deadlock). In s-deadlock, the entire
system gets blocked and is unable to make any transition. Cache coherence
protocols consist of N symmetric cache agents, where N is an unbounded
parameter; thus the verification of s-deadlock freedom is naturally a
parameterized verification problem. Parametrized verification techniques work
by using sound abstractions to reduce the unbounded model to a bounded model.
Efficient abstractions which work well for industrial scale protocols typically
bound the model by replacing the state of most of the agents by an abstract
environment, while keeping just one or two agents as is. However, leveraging
such efficient abstractions becomes a challenge for s-deadlock: a violation of
s-deadlock is a state in which the transitions of all of the unbounded number
of agents cannot occur and so a simple abstraction like the one above will not
preserve this violation. In this work we address this challenge by presenting a
technique which leverages high-level information about the protocols, in the
form of message sequence dia- grams referred to as flows, for constructing
invariants that are collectively stronger than s-deadlock. Efficient
abstractions can be constructed to verify these invariants. We successfully
verify the German and Flash protocols using our technique
Milk Yield of Dairy Buffaloes Supplemented with Yeast Solution and Yeast-fermented Cassava Pulp
Feed resource availability and quality are two of the major factors limiting dairy production in the Philippines. Utilization of microbial-based feed additives and agricultural by-products such as cassava pulp aided by fermentation technology can help provide the needed resource. This study aimed to determine the effect of activated yeast (Saccharomyces cerevisiae) solution (AYS) and yeast-fermented cassava pulp (YFCP) on milk production and feed cost-efficiency in dairy buffaloes. The study followed RCBD design using 63 dairy buffaloes at the Philippine Carabao Center in Ubay Stock Farm, Bohol. The average daily milk yield (ADMY) of buffaloes supplemented with 0.5L AYS and 1L AYS twice daily were greater than that of control buffaloes by 0.67L and 0.69L, respectively (P = 0.0039).On the other hand, the ADMY of buffaloes fed with YFCP and YFCP+AYS were greater than that of control buffaloes by 0.64 and 0.68L, respectively (P = 0.0320). Supplementation of AYS and feeding YFCP yielded the lowest cost per liter of milk produced at PhP 20.25 and PhP 16.24, respectively. It is recommended to supplement milking dairy buffaloes with AYS or feeding YFCP in areas with cassava pulp to increase feed resource, increase milk production and improve feed cost-efficiency thereby increasing significantly the farmer’s income
C–F bond activation of perfluorinated arenes by a bioxazoline-derived N-heterocyclic carbene
The N-heterocyclic carbene IBioxMe4 enacts selective single and double C–F bond activation of octafluorotoluene and hexafluorobenzene, respectively. The formation of the fluoroarene substituted, zwitterionic imidazoliumolate products is consistent with a mechanism involving nucleophilic aromatic substitution and subsequent oxazoline ring opening by liberated fluoride
UV-light promoted C–H bond activation of benzene and fluorobenzenes by an iridium(i) pincer complex
Iridium(I) carbonyl complex [Ir(2,6-(PtBu2CH2)2C6H3)(CO)] undergoes reversible C–H bond activation of benzene and a series of fluorobenzenes on UV irradiation. Exclusive ortho-selectivity is observed in reactions of fluorobenzene and 1,2-difluorobenzene
Negative Quasi-Probability as a Resource for Quantum Computation
A central problem in quantum information is to determine the minimal physical
resources that are required for quantum computational speedup and, in
particular, for fault-tolerant quantum computation. We establish a remarkable
connection between the potential for quantum speed-up and the onset of negative
values in a distinguished quasi-probability representation, a discrete analog
of the Wigner function for quantum systems of odd dimension. This connection
allows us to resolve an open question on the existence of bound states for
magic-state distillation: we prove that there exist mixed states outside the
convex hull of stabilizer states that cannot be distilled to non-stabilizer
target states using stabilizer operations. We also provide an efficient
simulation protocol for Clifford circuits that extends to a large class of
mixed states, including bound universal states.Comment: 15 pages v4: This is a major revision. In particular, we have added a
new section detailing an explicit extension of the Gottesman-Knill simulation
protocol to deal with positively represented states and measurement (even
when these are non-stabilizer). This paper also includes significant
elaboration on the two main results of the previous versio
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