180 research outputs found
Finite automata with advice tapes
We define a model of advised computation by finite automata where the advice
is provided on a separate tape. We consider several variants of the model where
the advice is deterministic or randomized, the input tape head is allowed
real-time, one-way, or two-way access, and the automaton is classical or
quantum. We prove several separation results among these variants, demonstrate
an infinite hierarchy of language classes recognized by automata with
increasing advice lengths, and establish the relationships between this and the
previously studied ways of providing advice to finite automata.Comment: Corrected typo
Quantum Optimization Problems
Krentel [J. Comput. System. Sci., 36, pp.490--509] presented a framework for
an NP optimization problem that searches an optimal value among
exponentially-many outcomes of polynomial-time computations. This paper expands
his framework to a quantum optimization problem using polynomial-time quantum
computations and introduces the notion of an ``universal'' quantum optimization
problem similar to a classical ``complete'' optimization problem. We exhibit a
canonical quantum optimization problem that is universal for the class of
polynomial-time quantum optimization problems. We show in a certain relativized
world that all quantum optimization problems cannot be approximated closely by
quantum polynomial-time computations. We also study the complexity of quantum
optimization problems in connection to well-known complexity classes.Comment: date change
A Dichotomy Theorem for the Approximate Counting of Complex-Weighted Bounded-Degree Boolean CSPs
We determine the computational complexity of approximately counting the total
weight of variable assignments for every complex-weighted Boolean constraint
satisfaction problem (or CSP) with any number of additional unary (i.e., arity
1) constraints, particularly, when degrees of input instances are bounded from
above by a fixed constant. All degree-1 counting CSPs are obviously solvable in
polynomial time. When the instance's degree is more than two, we present a
dichotomy theorem that classifies all counting CSPs admitting free unary
constraints into exactly two categories. This classification theorem extends,
to complex-weighted problems, an earlier result on the approximation complexity
of unweighted counting Boolean CSPs of bounded degree. The framework of the
proof of our theorem is based on a theory of signature developed from Valiant's
holographic algorithms that can efficiently solve seemingly intractable
counting CSPs. Despite the use of arbitrary complex weight, our proof of the
classification theorem is rather elementary and intuitive due to an extensive
use of a novel notion of limited T-constructibility. For the remaining degree-2
problems, in contrast, they are as hard to approximate as Holant problems,
which are a generalization of counting CSPs.Comment: A4, 10pt, 20 pages. This revised version improves its preliminary
version published under a slightly different title in the Proceedings of the
4th International Conference on Combinatorial Optimization and Applications
(COCOA 2010), Lecture Notes in Computer Science, Springer, Vol.6508 (Part I),
pp.285--299, Kailua-Kona, Hawaii, USA, December 18--20, 201
Characterization of metal-insulator-semicomductor capacitors with insulating nitride films grown on 4H-SiC
ArticleJAPANESE JOURNAL OF APPLIED PHYSICS. 47(1):676-678(2008)journal articl
Characterization of Al-based insulating films fabricated by physical vapor deposition
ArticleJAPANESE JOURNAL OF APPLIED PHYSICS. 47(1):609-611(2008)journal articl
Identification of freight patterns via association rules: the case of agricultural grains.
The road system is the main form of transport in the biggest production regions between the domestic market and exporting. ports, as well as the transport used on intermodal routes connecting production areas with rail and/or water terminals. The goal of the current study is to recognize non-obvious patterns in a mass of data for road freights of selected grain: soy and corn. As such, the data mining technique, known as the Apriori algorithm, is used to generate association rules that describe such patterns. Among the varied rules identified by this technique, we highlight those that enable us to conclude that: i. Soy and corn production in the state of Mato Grosso is carried via the port of Santos; ii. The grain storage silos located in the state of Mato Grosso mainly receive shipments from the same state; iii. The port of São Francisco do Sul, mainly receives corn; iv. In the state of Minas Gerais there is an intermodal route that receives the grain originating mostly from Mato Grosso and transfers it to the rail system, which then carries the load to its next destination
Quantum Computation Relative to Oracles
The study of the power and limitations of quantum computation remains a major challenge in complexity theory. Key questions revolve around the quantum complexity classes EQP, BQP, NQP, and their derivatives. This paper presents new relativized worlds in which (i) co-RP is not a subset of NQE, (ii) P=BQP and UP=EXP, (iii) P=EQP and RP=EXP, and (iv) EQP is not a subset of the union of Sigma{p}{2} and Pi{p}{2}. We also show a partial answer to the question of whether Almost-BQP=BQP
Classically time-controlled quantum automata
In this paper we introduce classically time-controlled quantum automata or CTQA, which is a slight but reasonable modification of Moore-Crutchfield quantum finite automata that uses time-dependent evolution operators and a scheduler defining how long each operator will run. Surprisingly enough, time-dependent evolutions provide a significant change in the computational power of quantum automata with respect to a discrete quantum model. Furthermore, CTQA presents itself as a new model of computation that provides a different approach to a formal study of “classical control, quantum data” schemes in quantum computing.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI
Computational Indistinguishability between Quantum States and Its Cryptographic Application
We introduce a computational problem of distinguishing between two specific
quantum states as a new cryptographic problem to design a quantum cryptographic
scheme that is "secure" against any polynomial-time quantum adversary. Our
problem, QSCDff, is to distinguish between two types of random coset states
with a hidden permutation over the symmetric group of finite degree. This
naturally generalizes the commonly-used distinction problem between two
probability distributions in computational cryptography. As our major
contribution, we show that QSCDff has three properties of cryptographic
interest: (i) QSCDff has a trapdoor; (ii) the average-case hardness of QSCDff
coincides with its worst-case hardness; and (iii) QSCDff is computationally at
least as hard as the graph automorphism problem in the worst case. These
cryptographic properties enable us to construct a quantum public-key
cryptosystem, which is likely to withstand any chosen plaintext attack of a
polynomial-time quantum adversary. We further discuss a generalization of
QSCDff, called QSCDcyc, and introduce a multi-bit encryption scheme that relies
on similar cryptographic properties of QSCDcyc.Comment: 24 pages, 2 figures. We improved presentation, and added more detail
proofs and follow-up of recent wor
Investigating the biological properties of carbohydrate derived fulvic acid (CHD-FA) as a potential novel therapy for the management of oral biofilm infections.
Background:
A number of oral diseases, including periodontitis, derive from microbial biofilms and are associated with increased antimicrobial resistance. Despite the widespread use of mouthwashes being used as adjunctive measures to control these biofilms, their prolonged use is not recommended due to various side effects. Therefore, alternative broad-spectrum antimicrobials that minimise these effects are highly sought after. Carbohydrate derived fulvic acid (CHD-FA) is an organic acid which has previously demonstrated to be microbiocidal against Candida albicans biofilms, therefore, the aims of this study were to evaluate the antibacterial activity of CHD-FA against orally derived biofilms and to investigate adjunctive biological effects.<p></p>
Methods:
Minimum inhibitory concentrations were evaluated for CHD-FA and chlorhexidine (CHX) against a range of oral bacteria using standardised microdilution testing for planktonic and sessile. Scanning electron microscopy was also employed to visualise changes in oral biofilms after antimicrobial treatment. Cytotoxicity of these compounds was assessed against oral epithelial cells, and the effect of CHD-FA on host inflammatory markers was assessed by measuring mRNA and protein expression.<p></p>
Results:
CHD-FA was highly active against all of the oral bacteria tested, including Porphyromonas gingivalis, with a sessile minimum inhibitory concentration of 0.5%. This concentration was shown to kill multi-species biofilms by approximately 90%, levels comparable to that of chlorhexidine (CHX). In a mammalian cell culture model, pretreatment of epithelial cells with buffered CHD-FA was shown to significantly down-regulate key inflammatory mediators, including interleukin-8 (IL-8), after stimulation with a multi-species biofilm.<p></p>
Conclusions:
Overall, CHD-FA was shown to possess broad-spectrum antibacterial activity, with a supplementary function of being able to down-regulate inflammation. These properties offer an attractive spectrum of function from a naturally derived compound, which could be used as an alternative topical treatment strategy for oral biofilm diseases. Further studies in vitro and in vivo are required to determine the precise mechanism by which CHD-FA modulates the host immune response.<p></p>
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