An Improved Private Mechanism for Small Databases

We study the problem of answering a workload of linear queries $\mathcal{Q}$, on a database of size at most $n = o(|\mathcal{Q}|)$ drawn from a universe $\mathcal{U}$ under the constraint of (approximate) differential privacy. Nikolov, Talwar, and Zhang~\cite{NTZ} proposed an efficient mechanism that, for any given $\mathcal{Q}$ and $n$, answers the queries with average error that is at most a factor polynomial in $\log |\mathcal{Q}|$ and $\log |\mathcal{U}|$ worse than the best possible. Here we improve on this guarantee and give a mechanism whose competitiveness ratio is at most polynomial in $\log n$ and $\log |\mathcal{U}|$, and has no dependence on $|\mathcal{Q}|$. Our mechanism is based on the projection mechanism of Nikolov, Talwar, and Zhang, but in place of an ad-hoc noise distribution, we use a distribution which is in a sense optimal for the projection mechanism, and analyze it using convex duality and the restricted invertibility principle.Comment: To appear in ICALP 2015, Track

Examining the effect of childhood animal cruelty motives on recurrent adult violent crimes toward humans

Few researchers have studied the predictive ability of childhood animal cruelty motives as they are associated with later recurrent violence toward humans. Based on a sample of 180 inmates at one medium- and one maximum-security prison in a Southern state, the present study examines the relationship among several retrospectively identified motives (fun, out of anger, hate for the animal, and imitation) for childhood animal cruelty and the later commission of violent crimes (murder, rape, assault, and robbery) against humans. Almost two-thirds of the inmates reported engaging in childhood animal cruelty for fun, whereas almost one-fourth reported being motivated either out of anger or imitation. Only one-fifth of the respondents reported they had committed acts of animal cruelty because they hated the animal. Regression analyses revealed that recurrent animal cruelty was the only statistically significant variable in the model. Respondents who had committed recurrent childhood animal cruelty were more likely to have had committed recurrent adult violence toward humans. None of the motives for committing childhood animal cruelty had any effect on later violence against humans

PHYTOSANITARY REGULATION AND AGRICULTURAL FLOWS: TOBACCO INPUTS AND CIGARETTES OUTPUTS

This paper examines the effects of the use of increasingly-popular phytosanitary regulations on production costs, and output and factor trade flows. The case addressed is that of the European regulation of maximum chemical residues in cigarettes manufactured with tobacco containing maleic hydrazide. The paper presents simulations of the effects of tightening the input/output market linkages and on the substitution away from the residue-contaminated U.S. input to residue-free non-U.S. inputs. This induced substitution results in higher costs, lower quantity supplied of the final product, and higher prices for U.S. cigarettes in Europe. Cross-price effects lead to higher quantities of EU cigarettes sold and a corresponding increase in the use of all inputs, including U.S. tobacco. When the U.S. tobacco price is allowed to fall, direct price effects stimulate the EU derived demand for U.S. tobacco. Although the regulation is protectionist in the output market, it leads to increased EU imports of the residue-contaminated input. When the price of U.S. tobacco adjusts, the regulation is actually antiprotective for EU growers. The regulation also indirectly influences production practices of U.S. tobacco growers and leads to lower levels of MH residues on U.S. leaf.Agricultural and Food Policy,

Faster k-Medoids Clustering: Improving the PAM, CLARA, and CLARANS Algorithms

Clustering non-Euclidean data is difficult, and one of the most used algorithms besides hierarchical clustering is the popular algorithm Partitioning Around Medoids (PAM), also simply referred to as k-medoids. In Euclidean geometry the mean-as used in k-means-is a good estimator for the cluster center, but this does not hold for arbitrary dissimilarities. PAM uses the medoid instead, the object with the smallest dissimilarity to all others in the cluster. This notion of centrality can be used with any (dis-)similarity, and thus is of high relevance to many domains such as biology that require the use of Jaccard, Gower, or more complex distances. A key issue with PAM is its high run time cost. We propose modifications to the PAM algorithm to achieve an O(k)-fold speedup in the second SWAP phase of the algorithm, but will still find the same results as the original PAM algorithm. If we slightly relax the choice of swaps performed (at comparable quality), we can further accelerate the algorithm by performing up to k swaps in each iteration. With the substantially faster SWAP, we can now also explore alternative strategies for choosing the initial medoids. We also show how the CLARA and CLARANS algorithms benefit from these modifications. It can easily be combined with earlier approaches to use PAM and CLARA on big data (some of which use PAM as a subroutine, hence can immediately benefit from these improvements), where the performance with high k becomes increasingly important. In experiments on real data with k=100, we observed a 200-fold speedup compared to the original PAM SWAP algorithm, making PAM applicable to larger data sets as long as we can afford to compute a distance matrix, and in particular to higher k (at k=2, the new SWAP was only 1.5 times faster, as the speedup is expected to increase with k)

On the action potential as a propagating density pulse and the role of anesthetics

The Hodgkin-Huxley model of nerve pulse propagation relies on ion currents through specific resistors called ion channels. We discuss a number of classical thermodynamic findings on nerves that are not contained in this classical theory. Particularly striking is the finding of reversible heat changes, thickness and phase changes of the membrane during the action potential. Data on various nerves rather suggest that a reversible density pulse accompanies the action potential of nerves. Here, we attempted to explain these phenomena by propagating solitons that depend on the presence of cooperative phase transitions in the nerve membrane. These transitions are, however, strongly influenced by the presence of anesthetics. Therefore, the thermodynamic theory of nerve pulses suggests a explanation for the famous Meyer-Overton rule that states that the critical anesthetic dose is linearly related to the solubility of the drug in the membranes.Comment: 13 pages, 8 figure

The Evolution of X-ray Bursts in the "Bursting Pulsar" GRO J1744-28

GRO J1744-28, commonly known as the `Bursting Pulsar', is a low mass X-ray binary containing a neutron star and an evolved giant star. This system, together with the Rapid Burster (MXB 1730-33), are the only two systems that display the so-called Type II X-ray bursts. These type of bursts, which last for 10s of seconds, are thought to be caused by viscous instabilities in the disk; however the Type II bursts seen in GRO J1744-28 are qualitatively very different from those seen in the archetypal Type II bursting source the Rapid Burster. To understand these differences and to create a framework for future study, we perform a study of all X-ray observations of all 3 known outbursts of the Bursting Pulsar which contained Type II bursts, including a population study of all Type II X-ray bursts seen by RXTE. We find that the bursts from this source are best described in four distinct phenomena or `classes' and that the characteristics of the bursts evolve in a predictable way. We compare our results with what is known for the Rapid Burster and put out results in the context of models that try to explain this phenomena.Comment: Accepted to MNRAS Aug 17 201

Combining education and science outcomes : the marine studies programme and Tūhua marine reserve monitoring

Tūhua (Mayor Island) lies 35 kilometres off shore in the Bay of Plenty, New Zealand. It has a long history of Māori occupation and is of high cultural significance to these traditional owners. Tūhua was once world-renowned for big game fishing, but after incremental declines in local fish populations, in 1993 a no-take marine reserve was gazetted and has been the subject of annual marine monitoring surveys since that time. Continued monitoring has only been possible because of the creation of an innovative science/education partnership between the Tūhua Trust Board, representing the indigenous Māori owners of the island, the Department of Conservation (DOC), responsible for managing the reserve, and the Marine Studies Department of Bay of Plenty Polytechnic (BOPP). The Polytechnic\u27s Marine Studies course is a successful undergraduate diploma/degree education programme, combining strong practical elements with academic rigour. Second year Marine Studies students and staff members undertake the marine monitoring surveys at Tūhua on an annual extended field trip. Managers expected the marine reserve would demonstrate growth in fish numbers in comparison to the adjacent less protected areas. However little change in key indicator species was apparent after ten years of protection and this precipitated a review of the methodology and marine management policies. Twenty years after protection, there are now clear differences. Interwoven with this hard science discourse are the perceptions of the students involved in the annual monitoring programme. On the extended monitoring field trip, the students and staff members live on the island for ten days in basic conditions and are immersed in a natural learning environment. Results of a series of questionnaires suggest that the students involved increase not only their skill sets but also have increased self-confidence, motivation and conservation awareness. Science and education outcomes have been successfully combined into a readily transferable model over twenty years at this ecologically and culturally significant island location.Keith E. Gregor: Marine Studies Department, Bay of Plenty PolytechnicKim D. Youg: Conservation Ecology Research Unit, Department of Zoology and Entomology, University of PretoriaDaniel C. Rapson: Tauranga Management Area, Department of ConservationJacob McC. Overton: Landcare Researc

The design and performance of an improved target for MICE

The linear motor driving the target for the Muon Ionisation Cooling Experiment has been redesigned to improve its reliability and performance. A new coil-winding technique is described which produces better magnetic alignment and improves heat transport out of the windings. Improved field-mapping has allowed the more precise construction to be demonstrated, and an enhanced controller exploits the full features of the hardware, enabling increased acceleration and precision. The new user interface is described and analysis of performance data to monitor friction is shown to allow quality control of bearings and a measure of the ageing of targets during use

Minimum Information about a Neuroscience Investigation (MINI) Electrophysiology

This module represents the formalized opinion of the authors and the CARMEN consortium, which identifies the minimum information required to report the use of electrophysiology in a neuroscience study, for submission to the CARMEN system (www.carmen.org.uk).
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