Differentially Private Exponential Random Graphs

We propose methods to release and analyze synthetic graphs in order to protect privacy of individual relationships captured by the social network. Proposed techniques aim at fitting and estimating a wide class of exponential random graph models (ERGMs) in a differentially private manner, and thus offer rigorous privacy guarantees. More specifically, we use the randomized response mechanism to release networks under $\epsilon$-edge differential privacy. To maintain utility for statistical inference, treating the original graph as missing, we propose a way to use likelihood based inference and Markov chain Monte Carlo (MCMC) techniques to fit ERGMs to the produced synthetic networks. We demonstrate the usefulness of the proposed techniques on a real data example.Comment: minor edit

Thermal Stabilization of the HCP Phase in Titanium

We have used a tight-binding model that is fit to first-principles electronic-structure calculations for titanium to calculate quasi-harmonic phonons and the Gibbs free energy of the hexagonal close-packed (hcp) and omega crystal structures. We show that the true zero-temperature ground-state is the omega structure, although this has never been observed experimentally at normal pressure, and that it is the entropy from the thermal population of phonon states which stabilizes the hcp structure at room temperature. We present the first completely theoretical prediction of the temperature- and pressure-dependence of the hcp-omega phase transformation and show that it is in good agreement with experiment. The quasi-harmonic approximation fails to adequately treat the bcc phase because the zero-temperature phonons of this structure are not all stable

Monitoring Cross-Linking, the Evolution of Refractive Index and the Glass Transition Temperature of an Epoxy Resin Using an Optical Fiber Sensor

Hyphenated analytical techniques enable the simultaneous measurement of relevant processing and materials parameters under identical environmental conditions. In the current study, a power-compensated differential scanning calorimeter (DSC) was custom-modified to enable the integration of an optical fibre sensor to monitor in situ the progression of the cross-linking reactions by inferring the evolution of the refractive index. A cleaved optical fibre was used and it served as a Fresnel reflection sensor (FRS). The DSC was calibrated with and without the integrated FRS and it was demonstrated that it did not influence the performance of the DSC. The FRS was calibrated using reference refractive index oils within the DSC. An epoxy/amine resin system was cross-linked at 70 ^oC and the enthalpy of cross-linking and the evolution of the refractive index were monitored simultaneously using the DSC and FRS respectively. After the cross-linking was completed, the DSC was programmed to perform a ramped heating schedule from ambient temperature to 150 ^oC. The FRS was capable of detecting glass transition temperature (Tg) of the cross-linked resin. An excellent correlation was observed for the Tg obtained by the FRS and DSC. The contribution of factors affecting the resolution of the data from the FRS are discussed.</p

Closed Loop Control of a Wing's Lift for 'Gust' Suppression

The ability to maintain a constant lift force on a low aspect ratio semi circular wing using pulsed blowing active flow control is experimentally investigated. Dynamic models of the wing’s response to pressure (pulsed blowing) actuation and the response to longitudinal gusting are obtained through black-box system identification methods. Robust closed loop controllers are synthesized using a mixed sensitivity loop shaping approach. An additional feedforward disturbance compensation is designed based on a model of the unsteady aerodynamics. The controllers show good suppression of lift fluctuations at low frequencies, but as frequencies increase the control performance degrades due to fundamental physical limitations. The limitations are related to the leading edge vortex formation time

Spin-dynamics simulations of the triangular antiferromagnetic XY model

Using Monte Carlo and spin-dynamics methods, we have investigated the dynamic behavior of the classical, antiferromagnetic XY model on a triangular lattice with linear sizes $L \leq 300$. The temporal evolutions of spin configurations were obtained by solving numerically the coupled equations of motion for each spin using fourth-order Suzuki-Trotter decompositions of exponential operators. From space- and time-displaced spin-spin correlation functions and their space-time Fourier transforms we obtained the dynamic structure factor $S({\bf q},w)$ for momentum ${\bf q}$ and frequency $\omega$. Below $T_{KT}$(Kosterlitz-Thouless transition), both the in-plane ($S^{xx}$) and the out-of-plane ($S^{zz}$) components of $S({\bf q},\omega)$ exhibit very strong and sharp spin-wave peaks. Well above $T_{KT}$, $S^{xx}$ and $S^{zz}$ apparently display a central peak, and spin-wave signatures are still seen in $S^{zz}$. In addition, we also observed an almost dispersionless domain-wall peak at high $\omega$ below $T_{c}$(Ising transition), where long-range order appears in the staggered chirality. Above $T_{c}$, the domain-wall peak disappears for all $q$. The lineshape of these peaks is captured reasonably well by a Lorentzian form. Using a dynamic finite-size scaling theory, we determined the dynamic critical exponent $z$ = 1.002(3). We found that our results demonstrate the consistency of the dynamic finite-size scaling theory for the characteristic frequeny $\omega_{m}$ and the dynamic structure factor $S({\bf q},\omega)$ itself.Comment: 8 pages, RevTex, 10 figures, submitted to PR

A weakly stable algorithm for general Toeplitz systems

We show that a fast algorithm for the QR factorization of a Toeplitz or Hankel matrix A is weakly stable in the sense that R^T.R is close to A^T.A. Thus, when the algorithm is used to solve the semi-normal equations R^T.Rx = A^Tb, we obtain a weakly stable method for the solution of a nonsingular Toeplitz or Hankel linear system Ax = b. The algorithm also applies to the solution of the full-rank Toeplitz or Hankel least squares problem.Comment: 17 pages. An old Technical Report with postscript added. For further details, see http://wwwmaths.anu.edu.au/~brent/pub/pub143.htm

Brigatinib (BRG) vs crizotinib (CRZ) in the phase III ALTA-1L trial

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Linear Responses in Time-dependent Hartree-Fock-Bogoliubov Method with Gogny Interaction

A numerical method to integrate the time-dependent Hartree-Fock Bogoliubov (TDHFB) equations with Gogny interaction is proposed. The feasibility of the TDHFB code is illustrated by the conservation of the energy, particle numbers, and center-of-mass in the small amplitude vibrations of oxygen 20. The TDHFB code is applied to the isoscalar quadrupole and/or isovector dipole vibrations in the linear (small amplitude) region in oxygen isotopes (masses A = 18,20,22 and 24), titanium isotopes (A = 44,50,52 and 54), neon isotope (A = 26), and magnesium isotopes (A = 24 and 34). The isoscalar quadrupole and isovector dipole strength functions are calculated from the expectation values of the isoscalar quadrupole and isovector dipole moments.Comment: 10 pages, 13 figure

Elastic Theory of Defects in Toroidal Crystals

We report a comprehensive analysis of the ground state properties of axisymmetric toroidal crystals based on the elastic theory of defects on curved substrates. The ground state is analyzed as a function of the aspect ratio of the torus, which provides a non-local measure of the underlying Gaussian curvature, and the ratio of the defect core-energy to the Young modulus. Several structural features are discussed,including a spectacular example of curvature-driven amorphization in the limit of the aspect ratio approaching one. The outcome of the elastic theory is then compared with the results of a numerical study of a system of point-like particles constrained on the surface of a torus and interacting via a short range potential.Comment: 24 pages, 24 figure

Reach in and reach out : the story of the MSc in pipeline engineering at Newcastle University

This paper presents an unusual case of university-industry interaction whereby a group of small businesses came together to persuade a university to establish an MSc in Pipeline Engineering. We identify that the course contributed to regional development in four ways. Firstly, it provided graduates for local industry. Secondly, it linked local firms with pipeline engineers world wide and raised the region's profile within that network. Thirdly, it strengthened the research base of the university through the recruitment of pipeline engineers from industry and fourthly, it facilitated the possibility of joint research between the university and local firms. We question whether this model is transferable to other industry sectors/universities. We conclude that this outreach activity has been shaped by the 'reach-in' to the university of the local business community and propose a revised model of university interaction with regional industry. Traditionally universities have been seen as 'reaching out' to regional industry and the collaborations have been viewed as being instigated by the university and often research-based. Our revised model proposes an alternative mechanism whereby collaborations can be instigated by industry and through a teaching-route