4,278 research outputs found
Alternating, private alternating, and quantum alternating realtime automata
We present new results on realtime alternating, private alternating, and
quantum alternating automaton models. Firstly, we show that the emptiness
problem for alternating one-counter automata on unary alphabets is undecidable.
Then, we present two equivalent definitions of realtime private alternating
finite automata (PAFAs). We show that the emptiness problem is undecidable for
PAFAs. Furthermore, PAFAs can recognize some nonregular unary languages,
including the unary squares language, which seems to be difficult even for some
classical counter automata with two-way input. Regarding quantum finite
automata (QFAs), we show that the emptiness problem is undecidable both for
universal QFAs on general alphabets, and for alternating QFAs with two
alternations on unary alphabets. On the other hand, the same problem is
decidable for nondeterministic QFAs on general alphabets. We also show that the
unary squares language is recognized by alternating QFAs with two alternations
Quantum key distribution with realistic states: photon-number statistics in the photon-number splitting attack
Quantum key distribution can be performed with practical signal sources such
as weak coherent pulses. One example of such a scheme is the Bennett-Brassard
protocol that can be implemented via polarization of the signals, or equivalent
signals. It turns out that the most powerful tool at the disposition of an
eavesdropper is the photon-number splitting attack. We show that this attack
can be extended in the relevant parameter regime such as to preserve the
Poissonian photon number distribution of the combination of the signal source
and the lossy channel.Comment: 4 page
Acceptance Ambiguity for Quantum Automata
We consider notions of freeness and ambiguity for the acceptance probability of Moore-Crutchfield Measure Once Quantum Finite Automata (MO-QFA). We study the distribution of acceptance probabilities of such MO-QFA, which is partly motivated by similar freeness problems for matrix semigroups and other computational models. We show that determining if the acceptance probabilities of all possible input words are unique is undecidable for 32 state MO-QFA, even when all unitary matrices and the projection matrix are rational and the initial configuration is defined over real algebraic numbers. We utilize properties of the skew field of quaternions, free rotation groups, representations of tuples of rationals as a linear sum of radicals and a reduction of the mixed modification Post\u27s correspondence problem
Research and Efforts in the Human Dimension: A Special Issue on Human-Systems Research in the U.S. Department of Energy
Operator-sum representation of time-dependent density operators and its applications
We show that any arbitrary time-dependent density operator of an open system
can always be described in terms of an operator-sum representation regardless
of its initial condition and the path of its evolution in the state space, and
we provide a general expression of Kraus operators for arbitrary time-dependent
density operator of an -dimensional system. Moreover, applications of our
result are illustrated through several examples.Comment: 4 pages, no figure, brief repor
Motivational dynamics of German Salafist jihadists: A multi-methodical in-depth study of three paradigmatic cases
Individuals belonging to terrorist organizations accept and often use violence as an instrument of their strategies to achieve their goals. The present study focuses on the motivational dynamics of three contrastively selected paradigmatic cases of extremists that grew up in Germany, joined and supported terrorist organizations abroad, and later disengaged and distanced themselves from the jihadist ideology. An innovative multi-methodical approach was applied to the interviews that combines a biographical reconstruction of the lived experiences with a psychoanalytically informed interpretation of the narratives. First, the biographical trajectories were analyzed on the manifest level: How have the former terrorists experienced their own pathways? What were relevant factors for their engagement in and disengagement from terrorism? Second, to gain a deeper understanding of the unconscious motivational dynamics for involvement in terrorism, key sequences of the narrative interviews were interpreted scenically in a psychoanalytical interpretation group: How did the interviewees express their lived experiences (and why in this particular way)? What latent meanings can be extrapolated that provide deep insights into the motivational backgrounds of their decisions? Based on the results of the triangulation process, characterizing structural hypotheses about case dynamics including protective and risk factors are presented and implications for prevention and intervention approaches are given
Stark effect and generalized Bloch-Siegert shift in a strongly driven two-level system
A superconducting qubit was driven in an ultrastrong fashion by an
oscillatory microwave field, which was created by coupling via the nonlinear
Josephson energy. The observed Stark shifts of the `atomic' levels are so
pronounced that corrections even beyond the lowest-order Bloch-Siegert shift
are needed to properly explain the measurements. The quasienergies of the
dressed two-level system were probed by resonant absorption via a cavity, and
the results are in agreement with a calculation based on the Floquet approach.Comment: 4+ page
Fruit scent and observer colour vision shape food-selection strategies in wild capuchin monkeys
The senses play critical roles in helping animals evaluate foods, including fruits that can change both in colour and scent during ripening to attract frugivores. Although numerous studies have assessed the impact of colour on fruit selection, comparatively little is known about fruit scent and how olfactory and visual data are integrated during foraging. We combine 25 months of behavioural data on 75 wild, white-faced capuchins (Cebus imitator) with measurements of fruit colours and scents from 18 dietary plant species. We show that frequency of fruit-directed olfactory behaviour is positively correlated with increases in the volume of fruit odours produced during ripening. Monkeys with red-green colour blindness sniffed fruits more often, indicating that increased reliance on olfaction is a behavioural strategy that mitigates decreased capacity to detect red-green colour contrast. These results demonstrate a complex interaction among fruit traits, sensory capacities and foraging strategies, which help explain variation in primate behaviour.https://www.nature.com/articles/s41467-019-10250-9Published versio
Socioeconomic status as a risk factor for dementia death:individual participant meta-analysis of 86 508 men and women from the UK
Background Life-course socioeconomic factors may have a role in dementia aetiology but there is a current paucity of studies. Meta-analyses of individual participant data would considerably strengthen this evidence base. Aims To examine the association between socioeconomic status in early life and adulthood with later dementia death. Method Individual participant meta-analysis of 11 prospective cohort studies (1994-2004, n = 86 508). Results Leaving full-time education at an earlier age was associated with an increased risk of dementia death in women (fully adjusted hazard ratio (HR) for age ⩽14 v. age ⩾16: HR = 1.76, 95% CI 1.23-2.53) but not men. Occupational social class was not statistically significantly associated with dementia death in men or women. Conclusions Lower educational attainment in women was associated with an increased risk of dementia-related death independently of common risk behaviours and comorbidities
Verification and Validation of Semantic Annotations
In this paper, we propose a framework to perform verification and validation
of semantically annotated data. The annotations, extracted from websites, are
verified against the schema.org vocabulary and Domain Specifications to ensure
the syntactic correctness and completeness of the annotations. The Domain
Specifications allow checking the compliance of annotations against
corresponding domain-specific constraints. The validation mechanism will detect
errors and inconsistencies between the content of the analyzed schema.org
annotations and the content of the web pages where the annotations were found.Comment: Accepted for the A.P. Ershov Informatics Conference 2019(the PSI
Conference Series, 12th edition) proceedin
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