653 research outputs found
Сучасні глобальні процеси у світовій економіці та їх вплив на економічну безпеку держави
Мета роботи. Визначення особливостей формування системи економічної безпеки держави, взагалі, та
України, зокрема, в сучасних умовах глобального розвитку світового господарства
The role of L1 use for L1 attrition
While the factor ‘language contact’ is often named among the most important for the development of individual language attrition, empirical validations of this claim are few and far between. This contribution argues that a bilingual’s use of the first language comprises very diverse situations which cannot be subsumed under one predictor variable. Grosjean’s (2001) framework of language modes is invoked as a useful way of structuring the use of the L1 by immigrants. A statistical investigation of these different types of L1 use on the one hand and language proficiency data on the other demonstrates that the impact of both active and passive exposure to the first language on attrition is anything but straightforward
An Algorithm for Strategic Continuation or Restriction of Asthma Medication Prior to Exercise Challenge Testing in Childhood Exercise Induced Bronchoconstriction
Exercise induced bronchial (EIB) constriction is a common and highly specific feature of pediatric asthma and should be diagnosed with an exercise challenge test (ECT). The impact of EIB in asthmatic children's daily lives is immense, considering the effects on both physical and psychosocial development. Monitoring childhood asthma by ECT's can provide insight into daily life disease burden and the control of asthma. Current guidelines for bronchoprovocation tests restrict both the use of reliever and maintenance asthma medication before an exercise challenge to prevent false-negative testing, as both have significant acute bronchoprotective properties. However, restricting maintenance medication before an ECT may be less appropiate to evaluate EIB symptoms in daily life when a diagnosis of asthma is well established. Rigorous of maintenance medication before an ECT according to guidelines may lead to overestimation of the real, daily life asthma burden and lead to an inappropiate step-up in therapy. The protection against EIB offered by the combined acute and chronic bronchoprotective effects of maintenance medication can be properly assessed whilst maintaining them. This may aid in achieving the goal of unrestricted participation of children in daily play and sports activities with their peers without escalation of therapy. When considering a step down in medication, a strategic wash-out of maintenance medication before an ECT aids in providing objective support of potential discontinuation of maintenance medication
First language attrition and reversion among older migrants
Emigration usually requires speakers to become bilingual, and eventually they may even become dominant in their second language. This can lead to a gradual loss of proficiency in the first language, a phenomenon referred to as first language attrition. As migrants become elderly, however, they sometimes report a "reversion" in language dominance, whereby the second language, which they have used in their daily lives for years or decades, recedes and the first language becomes stronger again. There are largely anecdotal cases of communication between such speakers and their children who were not brought up to speak their parents' first language becoming impossible. It is, however, very difficult to separate fact from fiction in such reports. This article will give an overview of changes in lexical access and fluency in the first language of adult migrants. It will assess simplistic predictions for a linear development of first and second languages against a more complex perspective which takes into account psycholinguistic aspects of activation, inhibition, and cognitive ageing. The predictions made on this basis will be tested on a large-scale quantitative investigation of language proficiency among migrants of German and Dutch descent in the Netherlands and Canada. © 2009 by Walter de Gruyter GmbH & Co. KG
Nearly optimal solutions for the Chow Parameters Problem and low-weight approximation of halfspaces
The \emph{Chow parameters} of a Boolean function
are its degree-0 and degree-1 Fourier coefficients. It has been known
since 1961 (Chow, Tannenbaum) that the (exact values of the) Chow parameters of
any linear threshold function uniquely specify within the space of all
Boolean functions, but until recently (O'Donnell and Servedio) nothing was
known about efficient algorithms for \emph{reconstructing} (exactly or
approximately) from exact or approximate values of its Chow parameters. We
refer to this reconstruction problem as the \emph{Chow Parameters Problem.}
Our main result is a new algorithm for the Chow Parameters Problem which,
given (sufficiently accurate approximations to) the Chow parameters of any
linear threshold function , runs in time \tilde{O}(n^2)\cdot
(1/\eps)^{O(\log^2(1/\eps))} and with high probability outputs a
representation of an LTF that is \eps-close to . The only previous
algorithm (O'Donnell and Servedio) had running time \poly(n) \cdot
2^{2^{\tilde{O}(1/\eps^2)}}.
As a byproduct of our approach, we show that for any linear threshold
function over , there is a linear threshold function which
is \eps-close to and has all weights that are integers at most \sqrt{n}
\cdot (1/\eps)^{O(\log^2(1/\eps))}. This significantly improves the best
previous result of Diakonikolas and Servedio which gave a \poly(n) \cdot
2^{\tilde{O}(1/\eps^{2/3})} weight bound, and is close to the known lower
bound of (1/\eps)^{\Omega(\log \log (1/\eps))}\} (Goldberg,
Servedio). Our techniques also yield improved algorithms for related problems
in learning theory
Variational method for learning Quantum Channels via Stinespring Dilation on neutral atom systems
The state of a closed quantum system evolves under the
Schr\"{o}dinger equation, where the reversible evolution of the state is
described by the action of a unitary operator on the initial state
, i.e.\ . However,
realistic quantum systems interact with their environment, resulting in
non-reversible evolutions, described by Lindblad equations. The solution of
these equations give rise to quantum channels that describe the
evolution of density matrices according to , which
often results in decoherence and dephasing of the state. For many quantum
experiments, the time until which measurements can be done might be limited,
e.g. by experimental instability or technological constraints. However, further
evolution of the state may be of interest. For instance, to determine the
source of the decoherence and dephasing, or to identify the steady state of the
evolution. In this work, we introduce a method to approximate a given target
quantum channel by means of variationally approximating equivalent unitaries on
an extended system, invoking the Stinespring dilation theorem. We report on an
experimentally feasible method to extrapolate the quantum channel on discrete
time steps using only data on the first time steps. Our approach heavily relies
on the ability to spatially transport entangled qubits, which is unique to the
neutral atom quantum computing architecture. Furthermore, the method shows
promising predictive power for various non-trivial quantum channels. Lastly, a
quantitative analysis is performed between gate-based and pulse-based
variational quantum algorithms.Comment: 11 pages, 7 figure
Approximately efficient two-sided combinatorial auctions
We develop and extend a line of recent work on the design of mechanisms for two-sided markets. e markets we consider consist of buyers and sellers of a number of items, and the aim of a mechanism is to improve the social welfare by arranging purchases and sales of the items. A mechanism is given prior distributions on the agents’ valuations of the items, but not the actual valuations; thus the aim is to maximise the expected social welfare over these distributions. As in previous work, we are interested in the worst-case ratio between the social welfare achieved by a truthful mechanism, and the best social welfare possible.
Our main result is an incentive compatible and budget balanced constant-factor approximation mechanism in a setting where buyers have XOS valuations and sellers’ valuations are additive. This is the rst such approximation mechanism for a two-sided market setting where the agents have combinatorial valuation functions. To achieve this result, we introduce a more general kind of demand query that seems to be needed in this situation. In the simpler case that sellers have unit supply (each having just one item to sell), we give a new mechanism whose welfare guarantee improves on a recent one in the literature. We also introduce a more demanding version of the strong budget balance (SBB) criterion, aimed at ruling out certain “unnatural” transactions satised by SBB. We show that the stronger version is satised by our mechanisms
Omgaan met digitale nationale beleidskaarten
In dit werkdocument worden de resultaten besproken van een casestudy die onderdeel is van het project GeO3 - Omgaan met onzekerheid binnen Ruimtelijke Ordening. De directie Platteland van het ministerie van LNV heeft bij het publiceren van het meerjarenprogramma van Agenda Vitaal Platteland geen digitale viewer gepubliceerd omdat men bang was voor verkeerde interpretatie van de digitale kaarten. In dit project is gekeken naar methoden en cartografische oplossingen om voortaan zonder angst voor misinterpretaties digitale nationale beleidskaarten te kunnen verspreiden. De oplossing is gezocht in het opstellen van een handreiking, zodat kaarten ook daadwerkelijk weergeven wat er bedoeld is door de maker
ParaDisEO-Based Design of Parallel and Distributed Evolutionary Algorithms
The original publication is available at www.springerlink.comInternational audienceParaDisEO is a framework dedicated to the design of parallel and distributed metaheuristics including local search methods and evolutionary algorithms. This paper focuses on the latter aspect. We present the three parallel and distributed models implemented in ParaDisEO and show how these can be exploited in a user-friendly, flexible and transparent way. These models can be deployed on distributed memory machines as well as on shared memory multi-processors, taking advantage of the shared memory in the latter case. In addition, we illustrate the instantiation of the models through two applications demonstrating the efficiency and robustness of the framework
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