Convex relaxation of mixture regression with efficient algorithms

We develop a convex relaxation of maximum a posteriori estimation of a mixture of regression models. Although our relaxation involves a semidefinite matrix variable, we reformulate the problem to eliminate the need for general semidefinite programming. In particular, we provide two reformulations that admit fast algorithms. The first is a max-min spectral reformulation exploiting quasi-Newton descent. The second is a min-min reformulation consisting of fast alternating steps of closed-form updates. We evaluate the methods against Expectation-Maximization in a real problem of motion segmentation from video data

Increasing value and reducing waste by optimizing the development of complex interventions: Enriching the development phase of the Medical Research Council (MRC) Framework

This is the final version of the article. Available from Elsevier via the DOI in this record.Background In recent years there has been much emphasis on ‘research waste’ caused by poor question selection, insufficient attention to previous research results, and avoidable weakness in research design, conduct and analysis. Little attention has been paid to the effect of inadequate development of interventions before proceeding to a full clinical trial. Objective We therefore propose to enrich the development phase of the MRC Framework by adding crucial elements to improve the likelihood of success and enhance the fit with clinical practice Methods Based on existing intervention development guidance and synthesis, a comprehensive iterative intervention development approach is proposed. Examples from published reports are presented to illustrate the methodology that can be applied within each element to enhance the intervention design. Results A comprehensive iterative approach is presented by combining the elements of the MRC Framework development phase with essential elements from existing guidance including: problem identification, the systematic identification of evidence, identification or development of theory, determination of needs, the examination of current practice and context, modelling the process and expected outcomes leading to final element: the intervention design. All elements are drawn from existing models to provide intervention developers with a greater chance of producing an intervention that is well adopted, effective and fitted to the context. Conclusion This comprehensive approach of developing interventions will strengthen the internal and external validity, minimize research waste and add value to health care research. In complex interventions in health care research, flaws in the development process immediately impact the chances of success. Knowledge regarding the causal mechanisms and interactions within the intended clinical context is needed to develop interventions that fit daily practice and are beneficial for the end-user

Be Your Own Curator with the CHIP Tour Wizard [html]

Web 2.0 enables increased access to the museum digital collection. More and more, users will spend time preparing their visits to the museums and reflecting on them after the visits. In this context, the CHIP (Cultural Heritage Information Personalization) project offers tools to the users to be their own curator, e.g. planning a personalized museum tour, discovering interesting artworks they want to see in a 'virtual' or a 'real' tour and quickly finding their ways in the museum. In this paper we present the new additions to the CHIP tools, which target the above functionality - a Web-based Tour Preparation Wizard and an export of a personalized tour to an interactive Mobile Guide used in the physical museum space. In addition, the user interactions during a real museum visit are stored and synchronized with the user model, which is maintained at the museum Web site

Be Your Own Curator with the CHIP Tour Wizard [pdf]

Web 2.0 enables increased access to the museum digital collection. More and more, users will spend time preparing their visits to the museums and reflecting on them after the visits. In this context, the CHIP (Cultural Heritage Information Personalization) project offers tools to the users to be their own curator, e.g. planning a personalized museum tour, discovering interesting artworks they want to see in a 'virtual' or a 'real' tour and quickly finding their ways in the museum. In this paper we present the new additions to the CHIP tools, which target the above functionality - a Web-based Tour Preparation Wizard and an export of a personalized tour to an interactive Mobile Guide used in the physical museum space. In addition, the user interactions during a real museum visit are stored and synchronized with the user model, which is maintained at the museum Web site

Формирование и продвижение кредитных продуктов и услуг

Кредитная услуга - одна из составляющих кредитной политики банка. Стремление к максимальному получению прибыли от ее предоставления и увеличению потока клиентов приводит к созданию комплекса (совокупности) услуг, а именно - кредитному продукту. Изучив интересы хозяйствующих субъектов, их потребности, банк может более точно разрабатывать приоритеты кредитной политики во взаимоотношениях с реальным сектором экономики. Обратная зависимость этого фактора - создание конкретного кредитного продукта и построение системы продвижения кредитных услуг, которая призвана осуществлять анализ, диагностику текущей ситуации, обеспечение взаимодействия между банками, нацелить взаимоотношения банка и заемщика на долгосрочную перспективу

Multipole interaction between atoms and their photonic environment

Macroscopic field quantization is presented for a nondispersive photonic dielectric environment, both in the absence and presence of guest atoms. Starting with a minimal-coupling Lagrangian, a careful look at functional derivatives shows how to obtain Maxwell's equations before and after choosing a suitable gauge. A Hamiltonian is derived with a multipolar interaction between the guest atoms and the electromagnetic field. Canonical variables and fields are determined and in particular the field canonically conjugate to the vector potential is identified by functional differentiation as minus the full displacement field. An important result is that inside the dielectric a dipole couples to a field that is neither the (transverse) electric nor the macroscopic displacement field. The dielectric function is different from the bulk dielectric function at the position of the dipole, so that local-field effects must be taken into account.Comment: 17 pages, to be published in Physical Review

Kernel Exponential Family Estimation via Doubly Dual Embedding

We investigate penalized maximum log-likelihood estimation for exponential family distributions whose natural parameter resides in a reproducing kernel Hilbert space. Key to our approach is a novel technique, doubly dual embedding, that avoids computation of the partition function. This technique also allows the development of a flexible sampling strategy that amortizes the cost of Monte-Carlo sampling in the inference stage. The resulting estimator can be easily generalized to kernel conditional exponential families. We establish a connection between kernel exponential family estimation and MMD-GANs, revealing a new perspective for understanding GANs. Compared to the score matching based estimators, the proposed method improves both memory and time efficiency while enjoying stronger statistical properties, such as fully capturing smoothness in its statistical convergence rate while the score matching estimator appears to saturate. Finally, we show that the proposed estimator empirically outperforms state-of-the-art methods in both kernel exponential family estimation and its conditional extension

Mesoscopic Cooperative Emission From a Disordered System

We study theoretically the cooperative light emission from a system of $N\gg 1$ classical oscillators confined within a volume with spatial scale, $L$, much smaller than the radiation wavelength, $\lambda_0=2\pi c/\omega_0$. We assume that the oscillators frequencies are randomly distributed around a central frequency, $\omega_0$, with some characteristic width, $\Omega\ll\omega_0$. In the absence of disorder, that is $\Omega=0$, the cooperative emission spectrum is composed of a narrow subradiant peak superimposed on a wide superradiant band. When $\Omega\neq 0$, we demonstrate that if $N$ is large enough, the subradiant peak is not simply broadened by the disorder but rather splits into a system of random narrow peaks. We estimate the spectral width of these peaks as a function of $N, L, \Omega$, and $\lambda_0$. We also estimate the amplitude of this mesoscopic structure in the emission spectrum.Comment: 25 pages including 6 figure