Invasion percolation and global optimization

Invasion bond percolation (IBP) is mapped exactly into Prim's algorithm for finding the shortest spanning tree of a weighted random graph. Exploring this mapping, which is valid for arbitrary dimensions and lattices, we introduce a new IBP model that belongs to the same universality class as IBP and generates the minimal energy tree spanning the IBP cluster.Comment: 4 pages, 3 Postscript figures avaliable from [email protected], REVTE

Managing M&A-From Strategic Intent to Integration: IOCs Acquisition of IBP and After

<div align=justify>This paper, in the nature of a case study, discusses the entire range of managerial issues addressed by Indian Oil Corporation Limited (IOC) in the acquisition, subsequent merger and post-merger integration of IBP Co. Limited (IBP) following IBP's disinvestment by the Government of India. The three stages of IBP transactions spanned a 5-6 year period from 2002 to 2007. The paper discusses from IOC's perspective, the strategic case for the IBP acquisition, rationale for what turned out to be an extremely aggressive bid price for IBP, the raison for subsequent merger, and the critical choices made by IOC management in post-merger integration of IBP. The paper also examines the controversies the IBP transactions generated in their wake and the corporate governance issues involved. We conclude that IOC appears to have handled the entire value chain of activities in the IBP transactions from acquisition planning and strategic evaluation through deal execution, post-acquisition merger, and to post-merger integration with a high level of professionalism, a balanced sense of priorities and a high degree of sensitivity, rarely seen in the Indian public sector milieu. We also believe that as Indian companies, particularly the larger state-owned enterprises, find themselves in the inevitable need to pursue M&A-based growth strategies, IOC's IBP experience should provide useful guidance in their endeavours. </div>

Posterior Contraction Rates of the Phylogenetic Indian Buffet Processes

By expressing prior distributions as general stochastic processes, nonparametric Bayesian methods provide a flexible way to incorporate prior knowledge and constrain the latent structure in statistical inference. The Indian buffet process (IBP) is such an example that can be used to define a prior distribution on infinite binary features, where the exchangeability among subjects is assumed. The phylogenetic Indian buffet process (pIBP), a derivative of IBP, enables the modeling of non-exchangeability among subjects through a stochastic process on a rooted tree, which is similar to that used in phylogenetics, to describe relationships among the subjects. In this paper, we study the theoretical properties of IBP and pIBP under a binary factor model. We establish the posterior contraction rates for both IBP and pIBP and substantiate the theoretical results through simulation studies. This is the first work addressing the frequentist property of the posterior behaviors of IBP and pIBP. We also demonstrated its practical usefulness by applying pIBP prior to a real data example arising in the field of cancer genomics where the exchangeability among subjects is violated

Antitubercular specific activity of ibuprofen and the other 2-arylpropanoic acids using the HT-SPOTi whole-cell phenotypic assay

Objectives: Lead antituberculosis (anti-TB) molecules with novel mechanisms of action are urgently required to fuel the anti-TB drug discovery pipeline. The aim of this study was to validate the use of the high-throughput spot culture growth inhibition (HT-SPOTi) assay for screening libraries of compounds against Mycobacterium tuberculosis and to study the inhibitory effect of ibuprofen (IBP) and the other 2-arylpropanoic acids on the growth inhibition of M tuberculosis and other mycobacterial species. Methods: The HT-SPOTi method was validated not only with known drugs but also with a library of 47 confirmed anti-TB active compounds published in the ChEMBL database. Three over-the-counter non-steroidal anti-inflammatory drugs were also included in the screening. The 2-arylpropanoic acids, including IBP, were comprehensively evaluated against phenotypically and physiologically different strains of mycobacteria, and their cytotoxicity was determined against murine RAW264.7 macrophages. Furthermore, a comparative bioinformatic analysis was employed to propose a potential mycobacterial target. Results: IBP showed antitubercular properties while carprofen was the most potent among the 2-arylpropanoic class. A 3,5-dinitro-IBP derivative was found to be more potent than IBP but equally selective. Other synthetic derivatives of IBP were less active, and the free carboxylic acid of IBP seems to be essential for its anti-TB activity. IBP, carprofen and the 3,5-dinitro-IBP derivative exhibited activity against multidrug-resistant isolates and stationary phase bacilli. On the basis of the human targets of the 2-arylpropanoic analgesics, the protein initiation factor infB (Rv2839c) of M tuberculosis was proposed as a potential molecular target. Conclusions: The HT-SPOTi method can be employed reliably and reproducibly to screen the antimicrobial potency of different compounds. IBP demonstrated specific antitubercular activity, while carprofen was the most selective agent among the 2-arylpropanoic class. Activity against stationary phase bacilli and multidrug-resistant isolates permits us to speculate a novel mechanism of antimycobacterial action. Further medicinal chemistry and target elucidation studies could potentially lead to new therapies against TB

Integration-by-parts identities in FDR

Four-dimensional renormalized (FDR) integrals play an increasingly important role in perturbative loop calculations. Thanks to them, loop computations can be performed directly in four dimensions and with no ultraviolet (UV) counterterms. In this paper I prove that integration-by-parts (IBP) identities can be used to find relations among multi-loop FDR integrals. Since algorithms based on IBP are widely applied beyond one loop, this result represents a decisive step forward towards the use of FDR in multi-loop calculations.Comment: 13 page

An Exercise in Invariant-based Programming with Interactive and Automatic Theorem Prover Support

Invariant-Based Programming (IBP) is a diagram-based correct-by-construction programming methodology in which the program is structured around the invariants, which are additionally formulated before the actual code. Socos is a program construction and verification environment built specifically to support IBP. The front-end to Socos is a graphical diagram editor, allowing the programmer to construct invariant-based programs and check their correctness. The back-end component of Socos, the program checker, computes the verification conditions of the program and tries to prove them automatically. It uses the theorem prover PVS and the SMT solver Yices to discharge as many of the verification conditions as possible without user interaction. In this paper, we first describe the Socos environment from a user and systems level perspective; we then exemplify the IBP workflow by building a verified implementation of heapsort in Socos. The case study highlights the role of both automatic and interactive theorem proving in three sequential stages of the IBP workflow: developing the background theory, formulating the program specification and invariants, and proving the correctness of the final implementation.Comment: In Proceedings THedu'11, arXiv:1202.453

Inappropriate use of proton-pump inhibitors and fragility fracture risk. A preliminary study

Introducción: Los inhibidores de la bomba de protones (IBP) son fármacos ampliamente utilizados, si bien esto conlleva a un sobreuso que no es acorde con las indicaciones aceptadas en España y en el resto de Europa. Por otro lado, algunos autores han establecido una posible implicación de los IBP en el riesgo de fractura. Con este trabajo hemos pretendido efectuar una primera aproximación al conocimiento del consumo de IBP en nuestro medio y analizar para qué indicación son prescritos, a la vez que estudiar su posible asociación con un mayor riesgo de fractura por fragilidad entre sus consumidores. Material y método: Estudio observacional, transversal, abierto, descriptivo, en el que se entrevistó aleatoriamente a un número de pacientes que fueron atendidos en diferentes ámbitos sanitarios: consultas externas hospitalarias, servicios de urgencias, consulta de Atención Primaria y pacientes ingresados en planta hospitalaria. Resultados: De los 411 pacientes entrevistados, el 54% de los pacientes recibían IBP, y cuya edad media era de 63,3 años, frente al 46% que no los tomaban y que eran más jóvenes, con una edad media de 50,9 años. La distribución por sexos fue similar. La principal razón de utilizar el IBP era como “protector gástrico”, en el 39,8% de los pacientes, indicación no existente en la ficha técnica de este grupo de fármacos. Los consumidores de IBP tenían una mayor prevalencia de todas las fracturas por fragilidad. Conclusiones: Más de la mitad de la población encuestada consume IBP, y de ella cerca del 40% sin una indicación médica correcta. Por esto, unido a la mayor prevalencia de fracturas por fragilidad que presentan –que nos hace pensar en un posible mayor riesgo de fractura entre sus usuarios– consideramos la necesidad de un uso más racional de estos fármacos. Estas conclusiones son preliminares pero, a la vista de estos resultados, creemos que puede ser interesante realizar más estudios dirigidos a comprobar de manera más firme la relación entre los IBP y el riesgo de fractura osteoporótica.Sociedad Canaria de Osteoporosi

Poisson Latent Feature Calculus for Generalized Indian Buffet Processes

The purpose of this work is to describe a unified, and indeed simple, mechanism for non-parametric Bayesian analysis, construction and generative sampling of a large class of latent feature models which one can describe as generalized notions of Indian Buffet Processes(IBP). This is done via the Poisson Process Calculus as it now relates to latent feature models. The IBP was ingeniously devised by Griffiths and Ghahramani in (2005) and its generative scheme is cast in terms of customers entering sequentially an Indian Buffet restaurant and selecting previously sampled dishes as well as new dishes. In this metaphor dishes corresponds to latent features, attributes, preferences shared by individuals. The IBP, and its generalizations, represent an exciting class of models well suited to handle high dimensional statistical problems now common in this information age. The IBP is based on the usage of conditionally independent Bernoulli random variables, coupled with completely random measures acting as Bayesian priors, that are used to create sparse binary matrices. This Bayesian non-parametric view was a key insight due to Thibaux and Jordan (2007). One way to think of generalizations is to to use more general random variables. Of note in the current literature are models employing Poisson and Negative-Binomial random variables. However, unlike their closely related counterparts, generalized Chinese restaurant processes, the ability to analyze IBP models in a systematic and general manner is not yet available. The limitations are both in terms of knowledge about the effects of different priors and in terms of models based on a wider choice of random variables. This work will not only provide a thorough description of the properties of existing models but also provide a simple template to devise and analyze new models.Comment: This version provides more details for the multivariate extensions in section 5. We highlight the case of a simple multinomial distribution and showcase a multivariate Levy process prior we call a stable-Beta Dirichlet process. Section 4.1.1 expande