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Observation of a comb of optical squeezing over many gigahertz of bandwith
No full textWe experimentally demonstrate the generation of optical
squeezing at multiple longitudinal modes and transverse Hermite-Gauss
modes of an optical parametric amplifier. We present measurements of
approximately 3 dB squeezing at baseband, 1.7 GHz, 3.4 GHz and 5.1 GHz
which correspond to the first, second and third resonances of the amplifier.
We show that both the magnitude and the bandwidth of the squeezing at
the higher longitudinal modes is greater than can be observed at baseband.
The squeezing observed is the highest frequency squeezing reported to date
Engineering benchmarks for planning: The domains used in the deterministic part of IPC-4
No full textIn a field of research about general reasoning mechanisms, it is essential to have appropriate benchmarks. Ideally, the benchmarks should reflect possible applications of the developed technology. In AI Planning, researchers more and more tend to draw their testing examples from the benchmark collections used in the International Planning Competition (IPC). In the organization of (the deterministic part of) the fourth IPC, IPC-4, the authors therefore invested significant effort to create a useful set of benchmarks. They come from five different (potential) real-world applications of planning: airport ground traffic control, oil derivative transportation in pipeline networks, model-checking safety properties, power supply restoration, and UMTS call setup. Adapting and preparing such an application for use as a benchmark in the IPC involves, at the time, inevitable (often drastic) simplifications, as well as careful choice between, and engineering of, domain encodings. For the first time in the IPC, we used compilations to formulate complex domain features in simple languages such as STRIPS, rather than just dropping the more interesting problem constraints in the simpler language subsets. The article explains and discusses the five application domains and their adaptation to form the PDDL test suites used in IPC-4. We summarize known theoretical results on structural properties of the domains, regarding their computational complexity and provable properties of their topology under the h+ function (an idealized version of the relaxed plan heuristic). We present new (empirical) results illuminating properties such as the quality of the most wide-spread heuristic functions (planning graph, serial planning graph, and relaxed plan), the growth of propositional representations over instance size, and the number of actions available to achieve each fact; we discuss these data in conjunction with the best results achieved by the different kinds of planners participating in IPC-4
Step size adaptation in reproducing kernel Hilbert space
No full textThis paper presents an online support vector machine (SVM) that uses the stochastic meta-descent
(SMD) algorithm to adapt its step size automatically. We formulate the online learning problem as
a stochastic gradient descent in reproducing kernel Hilbert space (RKHS) and translate SMD to the
nonparametric setting, where its gradient trace parameter is no longer a coefficient vector but an
element of the RKHS. We derive efficient updates that allow us to perform the step size adaptation
in linear time. We apply the online SVM framework to a variety of loss functions, and in particular
show how to handle structured output spaces and achieve efficient online multiclass classification.
Experiments show that our algorithm outperforms more primitive methods for setting the gradient
step size
When to coalesce: early versus late coalition announcement in an experimental democracy
No full textIn multi-party democracies, several parties usually have to join together in coalition to form government. Many aspects of that process have been fairly fully investigated, others less so. Among the latter is the timing of the formation and announcement of coalitions.
While the dominant popular image may be one of parties meeting together after the election to hammer out a coalition agreement, pre-election coalitions of one sort or another are actually quite common. In almost half of the elections in OECD (Organization for Economic Co-operation and Development) countries since the Second World War, at least one pair of parties had pre-announced their intention to join together in government. A quarter of governments formed were based wholly (and another quarter in part) on pre-election agreements.
To date, such studies as there have been of pre-election coalitions have concentrated primarily on system-level explanations – features of the electoral system (majoritarian or proportional, and so on) that make such arrangements more or less likely.3 Here we shall instead look more at the agent-level logic of ‘early’ (pre-election) versus ‘late’ (post-election) coalition formation, from the point of view of voters and parties.
HYPOTHESES CONCERNING COALITION TIMING:
In the tradition of Downs and Riker and their coalition-theorist progeny, we shall assume that voters are interested primarily in getting policies adopted which are close to their ‘ideal points’ in policy space, and that parties are interested primarily in winning office to implement policies as close as possible to their ‘ideal points’ in policy space. That leads parties to strive for ‘minimal connected winning coalitions’: ‘connected’ in the sense that they link parties adjacent in policy space; ‘minimal’ in the sense that they involve the party's sharing power with the fewest parties backed by fewest voters that it can and still win
Prices versus rationing: Marshallian surplus and mandatory water restrictions
No full textWe estimate an aggregate daily water demand for Sydney using rainfall, temperature, and price data for the period 1994-2005. The estimated demand is used to calculate the difference in Marshallian surplus between using the metered price of household water to regulate total consumption in Sydney versus mandatory water restrictions for the period 2004/2005. Using a choke price of 235 million for the period 1 June 2004 to 1 June 2005. On a per capita basis this equates to approximately 150 per household — a little less than half the average Sydney household water bill in 2005
Dynamics of matter-wave solitons in a ratchet potential
No full textWe study the dynamics of bright solitons formed in a Bose-Einstein condensate with attractive atomic
interactions perturbed by a weak bichromatic optical lattice potential. The lattice depth is a biperiodic
function of time with a zero mean, which realizes a flashing ratchet for matter-wave solitons. We find that
the average velocity of a soliton and the soliton current induced by the ratchet depend on the number of
atoms in the soliton. As a consequence, soliton transport can be induced through scattering of different
solitons. In the regime when matter-wave solitons are narrow compared to the lattice period the dynamics
is well described by the effective Hamiltonian theory
The effect of arsenic mitigation interventions on disease burden in Bangladesh
No full textMany interventions have been advocated to mitigate the impact of arsenic contamination of drinking water in Bangladesh. However, there are few data on the true magnitude of arsenic-related disease in Bangladesh nationally. There has also been little consideration given to possible adverse effects of such interventions, in particular, diarrheal disease. The purpose of this study was to estimate and compare the likely impacts of arsenic mitigation interventions on both arsenic-related disease and water-borne infectious disease. We found that arsenic-related disease currently results in 9,136 deaths per year and 174,174 disability-adjusted life years (DALYs ; undiscounted) lost per year in those exposed to arsenic concentrations > 50 µg/L. This constitutes 0.3% of the total disease burden in Bangladesh in terms of undiscounted DALYs. We found intervention to be of overall benefit in reducing disease burden in most scenarios examined, but the concomitant increase in water-related infectious disease significantly reduced the potential benefits gained from intervention. A minimum reduction in arsenic-related DALYs of 77% was necessary before intervention achieved any reduction in net disease burden. This is assuming that interventions were provided to those exposed to > 50 µg/L and would concomitantly result in a 20% increase in water-related infectious disease in those without access to adequate sanitation. Intervention appears to be justified for those populations exposed to high levels of arsenic, but it must be based on exposure levels and on the effectiveness of interventions not only in reducing arsenic but in minimizing risk of water-related infections
Historicizing "Cross-Cultural"
No full textIn 2000, a few years into the 10-year history
of the ANU’s Centre for Cross-Cultural
Research, a new field of research for the
Centre was announced: “Conceptualising
Cross-Cultural Research”, which in later
years became “Interrogating Concepts of
the Cross-Cultural”
Applying conditionality to development assistance
No full textThe announcement on 6 May 2004 by the Millennium Challenge
Corporation (MCC) of the 16 countries eligible to receive funding under
the Bush Administration’s Millennium Challenge Account (MCA) is a key
step in the process of determining the direction of development assistance by
applying quantitative international comparators to the governance performance of
developing countries. It is the latest in a series of conditionality strategies aimed
at making aid ‘effective’
Fast iterative kernel principal component analysis
No full textWe develop gain adaptation methods that improve convergence of the kernel Hebbian algorithm
(KHA) for iterative kernel PCA (Kim et al., 2005). KHA has a scalar gain parameter which is
either held constant or decreased according to a predetermined annealing schedule, leading to slow
convergence. We accelerate it by incorporating the reciprocal of the current estimated eigenvalues
as part of a gain vector. An additional normalization term then allows us to eliminate a tuning
parameter in the annealing schedule. Finally we derive and apply stochastic meta-descent (SMD)
gain vector adaptation (Schraudolph, 1999, 2002) in reproducing kernel Hilbert space to further
speed up convergence. Experimental results on kernel PCA and spectral clustering of USPS digits,
motion capture and image denoising, and image super-resolution tasks confirm that our methods
converge substantially faster than conventional KHA. To demonstrate scalability, we perform kernel
PCA on the entire MNIST data set