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George Christodoulou
2006
Psychiatric bulletin of the Royal College of Psychiatrists
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Mental health profile of Greece
2010
International Psychiatry
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19th century (Christodoulou et al, 2010). ...
Since the mid-1980s, a profound reform in the organisation of mental health provision has been taking place in Greece (Madianos & Christodoulou, 2007; Christodoulou, 2009). ...
the 19th century ( Christodoulou et al, 2010) . ...
pmid:31508042
pmcid:PMC6734981
fatcat:447n7pmyl5hdljfss7lvrqls2a
Management of the psychosocial effects of economic crises
2013
World Psychiatry
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Impartial selection with prior information
[article]
2021
arXiv
pre-print
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We study the problem of impartial selection, a topic that lies at the intersection of computational social choice and mechanism design. The goal is to select the most popular individual among a set of community members. The input can be modeled as a directed graph, where each node represents an individual, and a directed edge indicates nomination or approval of a community member to another. An impartial mechanism is robust to potential selfish behavior of the individuals and provides
arXiv:2102.09002v1
fatcat:yb2zg2jn3zalzlydkki4qr5xxu
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... e incentives to voters to report their true preferences by ensuring that the chance of a node to become a winner does not depend on its outgoing edges. The goal is to design impartial mechanisms that select a node with an in-degree that is as close as possible to the highest in-degree. We measure the efficiency of such a mechanism by the difference of these in-degrees, known as its additive approximation. In particular, we study the extent to which prior information on voters' preferences could be useful in the design of efficient deterministic impartial selection mechanisms with good additive approximation guarantees. We consider three models of prior information, which we call the opinion poll, the a prior popularity, and the uniform model. We analyze the performance of a natural selection mechanism that we call approval voting with default (AVD) and show that it achieves a O(√(nlnn)) additive guarantee for opinion poll and a O(ln^2n) for a priori popularity inputs, where n is the number of individuals. We consider this polylogarithmic bound as our main technical contribution. We complement this last result by showing that our analysis is close to tight, showing an Ω(lnn) lower bound. This holds in the uniform model, which is the simplest among the three models.
Financial Crises: Impact on Mental Health and Suggested Responses
2013
Psychotherapy and Psychosomatics
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Psychiatric reform revisited
2009
World Psychiatry
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The main points of criticism are the following:
Psychiatric reform revisited
PERSPECTIVE
GeorGe Christodoulou Hellenic Centre for Mental Health and Research, Athens, Greece The trend towards the ...
doi:10.1002/j.2051-5545.2009.tb00227.x
pmid:19516938
pmcid:PMC2694516
fatcat:vn7ro2vwanhb7poz5vsehlqjpu
The Royal College of Psychiatrists goes 'international': the European International Division
2005
International Psychiatry
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The initiative of the Royal College of Psychiatrists to establish international divisions has created considerable enthusiasm. College members have some common characteristics, mainly their training and success in the Royal College examination. Thus College members share a common approach to the practice of psychiatry as well as some common experiences; it can be argued that they share a common language in psychiatry.
pmid:31507822
pmcid:PMC6733139
fatcat:oe2ih23xp5fmnkme7vft3nhzpq
Strategic Contention Resolution in Multiple Channels
[article]
2018
arXiv
pre-print
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The theoretical works that relate the most to the current paper are the seminal paper by Fiat, Mansour and Nadav [11] and two by Christodoulou et al. ...
arXiv:1810.04565v1
fatcat:4h72mdgxc5cxppwcyf27rhaiei
A deterministic truthful PTAS for scheduling related machines
[article]
2009
arXiv
pre-print
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Scheduling on related machines (Q||C_) is one of the most important problems in the field of Algorithmic Mechanism Design. Each machine is controlled by a selfish agent and her valuation can be expressed via a single parameter, her speed. In contrast to other similar problems, Archer and Tardos AT01 showed that an algorithm that minimizes the makespan can be truthfully implemented, although in exponential time. On the other hand, if we leave out the game-theoretic issues, the complexity of the
arXiv:0907.3068v1
fatcat:mgyvvuysjvhixir6jcdnnlgjg4
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... roblem has been completely settled -- the problem is strongly NP-hard, while there exists a PTAS HS88,ES04. This problem is the most well studied in single-parameter algorithmic mechanism design. It gives an excellent ground to explore the boundary between truthfulness and efficient computation. Since the work of Archer and Tardos, quite a lot of deterministic and randomized mechanisms have been suggested. Recently, a breakthrough result DDDR08 showed that a randomized truthful PTAS exists. On the other hand, for the deterministic case, the best known approximation factor is 2.8 Kov05,Kov07. It has been a major open question whether there exists a deterministic truthful PTAS, or whether truthfulness has an essential, negative impact on the computational complexity of the problem. In this paper we give a definitive answer to this important question by providing a truthful deterministic PTAS.
On the Efficiency of All-Pay Mechanisms
[article]
2015
arXiv
pre-print
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Christodoulou , Kovács and Schapira [7] initiated the study of the (Bayesian) price of anarchy of simultaneous auctions with item-bidding. ...
Christodoulou et al. [8] constructed tight lower bounds for first-price auctions and showed a tight price of anarchy bound of 2 for all-pay auctions with subadditive valuations. ...
arXiv:1508.01130v1
fatcat:zczivforszb3bfvb24n3waltxu
Contention Resolution under Selfishness
2013
Algorithmica
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In many communications settings, such as wired and wireless local-area networks, when multiple users attempt to access a communication channel at the same time, a conflict results and none of the communications are successful. Contention resolution is the study of distributed transmission and retransmission protocols designed to maximize notions of utility such as channel utilization in the face of blocking communications. An additional issue to be considered in the design of such protocols is
doi:10.1007/s00453-013-9773-4
fatcat:7axnizr2hfbn3aznzimooonam4
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... hat selfish users may have incentive to deviate from the prescribed behavior, if another transmission strategy increases their utility. The work of Fiat et al. [8] addresses this issue by constructing an asymptotically optimal incentive-compatible protocol. However, their protocol assumes the cost of any single transmission is zero, and the protocol completely collapses under non-zero transmission costs. In this paper, we treat the case of non-zero transmission cost c. We present asymptotically optimal contention resolution protocols that are robust to selfish users, in two different channel feedback models. Our main result is in the Collision Multiplicity Feedback model, where after each time slot, the number of attempted transmissions is returned as feedback to the users. In this setting, we give a protocol that has expected cost 2n + c log n and is in o(1)-equilibrium, where n is the number of users.
Coordination Mechanisms
[chapter]
2004
Lecture Notes in Computer Science
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We introduce the notion of coordination mechanisms to improve the performance in systems with independent selfish and noncolluding agents. The quality of a coordination mechanism is measured by its price of anarchy-the worst-case performance of a Nash equilibrium over the (centrally controlled) social optimum. We give upper and lower bounds for the price of anarchy for selfish task allocation and congestion games.
doi:10.1007/978-3-540-27836-8_31
fatcat:h4ovmqoo5nf5bj5fielifq72ai
Coordination mechanisms
2009
Theoretical Computer Science
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We introduce the notion of coordination mechanisms to improve the performance in systems with independent selfish and noncolluding agents. The quality of a coordination mechanism is measured by its price of anarchy-the worst-case performance of a Nash equilibrium over the (centrally controlled) social optimum. We give upper and lower bounds for the price of anarchy for selfish task allocation and congestion games.
doi:10.1016/j.tcs.2009.01.005
fatcat:trpp2kb3jzex3pikstvhna7qr4
The Role of Twitter in YouTube Videos Diffusion
[chapter]
2012
Lecture Notes in Computer Science
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This work is supported in part by the Startup Grant [George Pallis, 2011], funded by the University of Cyprus. ...
doi:10.1007/978-3-642-35063-4_31
fatcat:jovnlzihbzckzafncxjpmhu2gy
Truthful Aggregation of Budget Proposals with Proportionality Guarantees
[article]
2022
arXiv
pre-print
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We study a participatory budgeting problem, where a set of strategic agents wish to split a divisible budget among different projects, by aggregating their proposals on a single division. Unfortunately, the straight-forward rule that divides the budget proportionally is susceptible to manipulation. In a recent work, Freeman et al. [arXiv:1905.00457] proposed a class of truthful mechanisms, called moving phantom mechanisms. Among others, they propose a proportional mechanism, in the sense that
arXiv:2203.09971v1
fatcat:slnkpzny65bfznezzoyyq7fnoe
more »
... the extreme case where all agents prefer a single project to receive the whole amount, the budget is assigned proportionally. While proportionality is a naturally desired property, it is defined over a limited type of preference profiles. To address this, we expand the notion of proportionality, by proposing a quantitative framework which evaluates a budget aggregation mechanism according to its worst-case distance from the proportional allocation. Crucially, this is defined for every preference profile. We study this measure on the class of moving phantom mechanisms, and we provide approximation guarantees. For two projects, we show that the Uniform Phantom mechanism is the optimal among all truthful mechanisms. For three projects, we propose a new, proportional mechanism which is virtually optimal among all moving phantom mechanisms. Finally, we provide impossibility results regarding the approximability of moving phantom mechanisms.
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