Joining Spacetimes on Fractal Hypersurfaces

The theory of fractional calculus is attracting a lot of attention from mathematicians as well as physicists. The fractional generalisation of the well-known ordinary calculus is being used extensively in many fields, particularly in understanding stochastic process and fractal dynamics. In this paper, we apply the techniques of fractional calculus to study some specific modifications of the geometry of submanifolds. Our generalisation is applied to extend the Israel formalism which is used to glue together two spacetimes across a timelike, spacelike or a null hypersurface. In this context, we show that the fractional extrapolation leads to some striking new results. More precisely we demonstrate that, in contrast to the original Israel formalism, where many spacetimes can only be joined together through an intermediate thin hypersurface of matter satisfying some non- standard energy conditions, the fractional generalisation allows these spacetimes to be smoothly sewed together without any such requirements on the stress tensor of the matter fields. We discuss the ramifications of these results for spacetime structure and the possible implications for gravitational physics.Comment: 22 pages, 2 figure

Coarse-to-Fine Lifted MAP Inference in Computer Vision

There is a vast body of theoretical research on lifted inference in probabilistic graphical models (PGMs). However, few demonstrations exist where lifting is applied in conjunction with top of the line applied algorithms. We pursue the applicability of lifted inference for computer vision (CV), with the insight that a globally optimal (MAP) labeling will likely have the same label for two symmetric pixels. The success of our approach lies in efficiently handling a distinct unary potential on every node (pixel), typical of CV applications. This allows us to lift the large class of algorithms that model a CV problem via PGM inference. We propose a generic template for coarse-to-fine (C2F) inference in CV, which progressively refines an initial coarsely lifted PGM for varying quality-time trade-offs. We demonstrate the performance of C2F inference by developing lifted versions of two near state-of-the-art CV algorithms for stereo vision and interactive image segmentation. We find that, against flat algorithms, the lifted versions have a much superior anytime performance, without any loss in final solution quality.Comment: Published in IJCAI 201

Characterization of color cross-talk of CCD detectors and its influence in multispectral quantitative phase imaging

Multi-spectral quantitative phase imaging (QPI) is an emerging imaging modality for wavelength dependent studies of several biological and industrial specimens. Simultaneous multi-spectral QPI is generally performed with color CCD cameras. However, color CCD cameras are suffered from the color crosstalk issue, which needed to be explored. Here, we present a new approach for accurately measuring the color crosstalk of 2D area detectors, without needing prior information about camera specifications. Color crosstalk of two different cameras commonly used in QPI, single chip CCD (1-CCD) and three chip CCD (3-CCD), is systematically studied and compared using compact interference microscopy. The influence of color crosstalk on the fringe width and the visibility of the monochromatic constituents corresponding to three color channels of white light interferogram are studied both through simulations and experiments. It is observed that presence of color crosstalk changes the fringe width and visibility over the imaging field of view. This leads to an unwanted non-uniform background error in the multi-spectral phase imaging of the specimens. It is demonstrated that the color crosstalk of the detector is the key limiting factor for phase measurement accuracy of simultaneous multi-spectral QPI systems.Comment: 16 pages, 8 figure

Modeling Psychrometric Data in Real-Time Fruit Logistics Monitoring

Progress in fruit logistics requires an increasing number of measurements to be performed in refrigerated chambers and during transport. Fruits and vegetables are submitted to a variety of risks during transport and storage that are responsible for material quality losses. Among them water loss and condensation are causes of deterioration that reduces the marketability of fresh fruits and vegetables. Wireless sensor networks (WSN) are a promising solution in monitoring food logistics. Instrumented with sensors, such as temperature and humidity, this technology allows on-line supply chain monitoring of perishable food products. Psychrometry studies the thermodynamic properties of moist air and the use of these properties to analyze conditions and processes involving moist air. Using the information provided by the sensors, psychrometric equations can be used for quick assessment of changes in the absolute water content of air, allowing estimation of future water loss and detection of condensation. In this paper the psychrometric data from ASABE (American Society of Agricultural and Biological Engineers) has been applied, for modeling evaporation and condensation of water related with regard to product in a refrigerated chamber. The experiments were conducted in a commercial wholesaler store in the fruit and vegetables wholesalers market of Madrid. Two different types of IEEE 802.15.4/ ZigBee motes have been used

Monitorización de Transportes frigoríficos de hortalizas mediante Redes Inalámbricas de Sensores tipo ZigBee

Los productos alimentarios perecederos tales como hortalizas, frutas, carne o pescado requieren transporte refrigerado. El control de la calidad y supervisión de los productos durante su transporte y distribución es de gran importancia para los operadores logísticos, donde el mayor reto es asegurar una cadena de frio continua desde el productor hasta el consumidor. Las empresas involucradas necesitan mejores métodos que garanticen la calidad de sus productos de cara a los consumidores. Para optimizar las condiciones de transporte de los productos alimentarios es necesario desarrollar sistemas automáticos de monitorización y control de los envíos. El presente artículo presenta un estudio experimental de monitorización de un transporte frigorífico de lechugas Little Gem (Lechuga baby o cogollo) desde Murcia hasta Francia, usando una red inalámbrica de sensores basada en el protocolo ZigBee/IEEE 802.15.4. La red estaba compuesta de cuatro nodos y una puerta de enlace. Las condiciones de transporte, fiabilidad de las comunicaciones y propiedades psicrométricas han sido analizadas. La aplicación del modelo psicrométrico de la ASABE permitió la detección inmediata de los cambios en contenido del agua del ambiente, estimando la condensación sobre la superficie del producto y las pérdidas de agua del mismo

Assessing the Role of Marketing at Earnings Announcement: Stock Market Response to Marketing Metrics Surprises

The explanatory power of earnings per share (eps) is on the decline as firms are focusing more on intangible assets and are disclosing more marketing metrics when they announce their earnings (e.g., subscribers for the telecom & media industry and monthly active users for social media industry). However, the performance of these marketing output metrics beyond market/analysts’ expectations (i.e., surprises) requires marketing resources, which may reduce current profitability but may also signal a higher future cash flow. Therefore, building on information economics, we assess if there is information content in marketing metric surprises, and how the stock market reacts to such surprises. Further, we argue that the information content of marketing metric surprises varies under different information signals by firms (strategic emphasis) and screening cues by investors (marketing expenditure). We also investigate the temporal variations in the effect of marketing metric surprises and also examine the relative importance of marketing metric surprises as compared to earnings surprises across multiple industries. We test the claims using an event study methodology around earnings announcement on S&P 1500 firms consisting of firms disclosing industry-specific marketing metrics and non-disclosing firms. We account for sample selection bias and correcting for potential endogeneity concerns of surprises marketing metrics. Our findings suggest that (1) although an increase in marketing metric surprise affects the stock market returns positively, (2) this effect is strengthened when firms signal strategic emphasis on value appropriation relative to value creation whereas (3) it is attenuated when investors screen for firms with higher unanticipated marketing expenditure, (4) the effect of marketing metric surprises increases over time whereas it decreases for earnings surprise, and (5) the effect of marketing metric surprise is higher in the telecom and media industry as compared to earnings surprises. The study helps to improve marketing accountability at the time of earnings announcement by improving the overall earnings quality of firms