Prioritizing relevance judgments to improve the construction of IR test collections

We consider the problem of optimally allocating a fixed budget to construct a test collection with associated relevance judgements, such that it can (i) accurately evaluate the relative performance of the participating systems, and (ii) generalize to new, previously unseen systems. We propose a two stage approach. For a given set of queries, we adopt the traditional pooling method and use a portion of the budget to evaluate a set of documents retrieved by the participating systems. Next, prioritize the queries and associated documents for further refinement of the test collection. Our objective is to increase the effectiveness of the test collection for comparative evaluation and extendibility to new systems. The query prioritization is formulated as a convex optimization problem, thereby permitting efficient solution and providing a flexible framework to incorporate various constraints. We use the remaining budget to evaluate query-document pairs with the highest priority scores. The budgets for the initial and the refinement phase are expended during the construction of the test collection and consider only the documents that have been retrieved by the participating systems. We evaluate our resource optimization approach on two TREC test collections namely TREC 8 and TREC 2004 Robust Track. We demonstrate that our optimization techniques are cost efficient and yield a significant improvement in the reusability of the test collections

More efficient lateral load patterns for seismic design of steel moment resisting frames

The preliminary design of building structures is normally based on the equivalent lateral forces provided in seismic design guidelines. The height-wise distribution of these loads is predominantly based on elastic vibration modes. However, as structures exceed their elastic limits in severe earthquakes, these design load patterns may not necessarily lead to efficient distribution of strength within the structures. To address this issue, several alternative load patterns have been proposed for the seismic design of non-linear structures. However, due to the simplifications involved in the development of these design load patterns, their adequacy needs to be assessed for different structural systems and earthquake excitations before they can be used in common practice. The aim of this work was to identify the most suitable lateral load patterns for the seismic design of steel moment-resisting frames. To do this, the non-linear seismic behaviour of three-, five-, seven-, ten- and 15-storey frames designed with nine different lateral load patterns were compared under 20 real and synthetic spectrum-compatible earthquakes using performance parameters such as maximum inter-storey drift, maximum plastic hinge rotation and cumulative damage. It was found that, for the same structural weight, structures designed with more efficient load patterns experienced up to 68% less global damage than their code-based counterparts

Neutrino spin oscillations in gravitational fields

We study neutrino spin oscillations in black hole backgrounds. In the case of a charged black hole, the maximum frequency of oscillations is a monotonically increasing function of the charge. For a rotating black hole, the maximum frequency decreases with increasing the angular momentum. In both cases, the frequency of spin oscillations decreases as the distance from the black hole grows. As a phenomenological application of our results, we study simple bipolar neutrino system which is an interesting example of collective neutrino oscillations. We show that the precession frequency of the flavor pendulum as a function of the neutrino number density will be higher for a charged/non-rotating black hole compared with a neutral/rotating black hole respectively.Comment: Replaced with the version accepted for publication in Gravitation and Cosmology, Springer. 10 pages. 4 figure

A Framework for the Game-theoretic Analysis of Censorship Resistance

We present a game-theoretic analysis of optimal solutions for interactions between censors and censorship resistance systems (CRSs) by focusing on the data channel used by the CRS to smuggle clients’ data past the censors. This analysis leverages the inherent errors (false positives and negatives) made by the censor when trying to classify traffic as either non-circumvention traffic or as CRS traffic, as well as the underlying rate of CRS traffic. We identify Nash equilibrium solutions for several simple censorship scenarios and then extend those findings to more complex scenarios where we find that the deployment of a censorship apparatus does not qualitatively change the equilibrium solutions, but rather only affects the amount of traffic a CRS can support before being blocked. By leveraging these findings, we describe a general framework for exploring and identifying optimal strategies for the censorship circumventor, in order to maximize the amount of CRS traffic not blocked by the censor. We use this framework to analyze several scenarios with multiple data-channel protocols used as cover for the CRS. We show that it is possible to gain insights through this framework even without perfect knowledge of the censor’s (secret) values for the parameters in their utility function

Ultrafast Electron Holes in Plasma Phase Space Dynamics

Electron holes (EH) are localized modes in plasma kinetic theory which appear as vortices in phase space. Earlier research on EH is based on the Schamel distribution function (df). A novel distribution function is proposed here, generalizing the original Schamel df in a recursive manner. Nonlinear solutions obtained by kinetic simulations are presented, with velocities twice the electron thermal speed. Using 1D-1V kinetic simulations, their propagation characteristics are traced and their stability is established by studying their long-time evolution and their behavior through mutual collisions.Comment: 5 pages, 6 figures, accepted in Scientific Report

A Principal-Agent Theory Perspective on PPP Risk Allocation

This study proposes a framework for the allocation of risk in public private partnerships (PPP) projects. Its contribution lies in the recognition and incorporation of risks introduced by project stakeholders, and as articulated by the principal-agent theory (PAT). The framework assesses risks and routes these risks to those parties best equipped to mitigate their impact on the project. This allocation of risk is facilitated by a thirteen-step process. The practical benefit of this study lies in outlining a clear, systematic method for allocating risk efficiently to both the government and private enterprise parties of the project. In so doing, risk mitigation can be expected to improve project performance, optimize stakeholder goals, and enhance sustainability objectives, including improved operational life-cycle efficiency and elevated social and community benefits

Non-surgical removal of some stones from a red tailed catfish (Phractocephalus hemioliopterus) stomach as gastric foreign bodies

A red-tailed catfish (Phractocephalus hemioliopterus) referred to Aquatic Animal Health Department, Faculty of Veterinary Medicine, University of Tehran for showing lethargy, bottom sitting, extension of abdomen and severe abdominal injuries. Its abdomen was swollen and the bulk of the foreign bodies were easily palpated. The heaviness of foreign bodies had made swimming and buoyancy difficult for fish. Several radiographic images were taken after anaesthetizing the catfish with 10% carvacrol, 2 drops in 1 liter of water. Radiographs revealed some stones with their size, number and location. Stones were removed non-surgically through the large oral cavity using suitable forceps. Totally 16 stones and 2 shells were removed from the stomach of the fish. The catfish was then returned to the water where normal swimming and buoyancy was restored

Residual absorption at zero temperature in d-wave superconductors

In a d-wave superconductor with elastic impurity scattering, not all the available optical spectral weight goes into the condensate at zero temperature, and this leads to residual absorption. We find that for a range of impurity parameters in the intermediate coupling regime between Born (weak) and unitary (strong) limit, significant oscillator strength remains which exhibits a cusp like behavior of the real part of the optical conductivity with upward curvature as a function of frequency, as well as a quasilinear temperature dependence of the superfluid density. The calculations offer an explanation of recent data on ortho-II YBa$_2$Cu$_3$O$_{6.5}$ which has been considered anomalous.Comment: Accepted for publication by Phys. Rev. B 7 Pages and 4 Figure