Inverse Covariance Estimation for High-Dimensional Data in Linear Time and Space: Spectral Methods for Riccati and Sparse Models

We propose maximum likelihood estimation for learning Gaussian graphical models with a Gaussian (ell_2^2) prior on the parameters. This is in contrast to the commonly used Laplace (ell_1) prior for encouraging sparseness. We show that our optimization problem leads to a Riccati matrix equation, which has a closed form solution. We propose an efficient algorithm that performs a singular value decomposition of the training data. Our algorithm is O(NT^2)-time and O(NT)-space for N variables and T samples. Our method is tailored to high-dimensional problems (N gg T), in which sparseness promoting methods become intractable. Furthermore, instead of obtaining a single solution for a specific regularization parameter, our algorithm finds the whole solution path. We show that the method has logarithmic sample complexity under the spiked covariance model. We also propose sparsification of the dense solution with provable performance guarantees. We provide techniques for using our learnt models, such as removing unimportant variables, computing likelihoods and conditional distributions. Finally, we show promising results in several gene expressions datasets.Comment: Appears in Proceedings of the Twenty-Ninth Conference on Uncertainty in Artificial Intelligence (UAI2013

Effects Of Production Location And Internationalization Mode On Product Prices: A Real Market Test

Two of the most important decisions that a multinational enterprise (MNE) or internationalizing firm face are: (1) Where should production be located to serve a specific market? and (2) How should this market be served--through exports, wholly-owned subsidiary production, joint venture, or licensing? These two questions have been studied at length in the international business literature. In these studies, however, the emphasis has been on the comparative costs of alternative country sites and market servicing modes. The product pricing side of these questions has been relatively neglected. This dissertation studies the effects of different production countries-of-origin and market servicing modes on prices of 445 products being sold in an informal economy smuggler\u27s market in the Philippines. Firm-specific effects were controlled for by comparing products made by the same MNE. In addition, interviews were conducted with managers of eight MNEs and a non-MNE in the Philippines to discuss qualitative managerial issues on location and mode.;The international marketing literature has shown that buyers exhibit country-of-origin preferences. Most of these studies used hypothetical products and hypothetical buying situations. This dissertation uses prices of real products in a real market to test the hypothesis that buyers prefer products produced in more developed countries, over products produced in lesser developed countries.;Some MNE scholars have suggested that product quality can be affected by the choice of mode in servicing a foreign market. However, this hypothesis has not been empirically tested. This dissertation tests the hypothesis that buyers will prefer products produced by more internalized modes of production. It is assumed that preference for higher product quality will be reflected in the price premiums of preferred goods.;The price premium data collected for this dissertation is analyzed using OLS regression. The results support the hypotheses that buyers prefer products produced from more developed countries over lesser developed countries, that branding decreases these price premiums, that purchase risk increases the price premiums, and that goods produced through more internalized modes are preferred.;The interviews with the managers generally supported the findings of the price analysis. Finally, a number of managerial implications was drawn from the results

Precooling Parameters Of 'roxo De Valinhos' Figs (ficus Carica L.) Packed In A Carton Box

Introduction. Figs of the variety 'Roxo de Valinhos' are currently cooled in a cold room at a temperature between (1 and 3)°C, and it is unknown how long it takes to cool the fruits to that temperature. The work was based on the need to determine the parameters of forced-air precooling of figs packed in a carton box used for exportation and commercialization in São Paulo State, Brazil. Materials and methods. The fruits were harvested at the harvest rami stage (3/4 of maturity) and at size "type 8", corresponding to eight fruits per box, making up a total of 24 fruits per package. Forty-eight packages were utilized, 24 on each side to form a Californian tunnel. The airflow was 2.8 L·s-1 per kg of product, with an average velocity of the air of 2.0 m·s-1. The initial interior temperature of the fruits was 20°C and the final temperature was 1°C. The evolution of the fig interior temperature was registered. Results. The cooling curve was drawn and the exponential analytical model to predict the precooling parameters was made based on the experimental data. The cooling curve of fig showed a typical behavior; the average fruit temperature during precooling presented a rapid fall at the beginning of the cooling, and slowly declined when it was close to the final temperature. Conclusion. The cooling time was 110 min, the cooling coefficient was 0.0344 min-1, the Biot number was 1.3 and the convective heat transference coefficient was 23.8°C·W -1·m-2. © 2006 Cirad/EDP Sciences All rights reserved.616401406Turk, R., Effects of harvest time and pre-cooling on fruit quality and cold storage of Ficus carica L. cv. 'Bursa syahjiu (1989) Acta Hortic, 258, pp. 279-285Dincer, I., Thermal cooling data for figs exposed to air cooling (1995) Int. Commun. Heat Mass Transf, 22, pp. 559-566Dincer, I., Transient heat transfer analysis in air cooling of individual spherical products (1995) J. Food Eng, 26, pp. 453-467Leal P.A.M., Cortez L.A.B., Métodos de préresfriamento de frutas e hortalizas, in: II Curso Atual. Tecnol. Resfr. Frut. Hortal., Fac. Eng. Agríc. (UNICAMP), Campinas-SP, Brazil, 1998, pp. 81-91Talbot, M.T., Chau, K.V., (1991) Precooling strawberries, p. 942. , Inst. Food Agric. Sci, Univ. Fla, Circ, USAFraser H.W., Forced-air cooling of fresh Ontario fruits and vegetables, Minist. Agric. Food., Toronto, Ontario, 1991Chau K.V., Mathematical modelling of postharvest processes, Grupo Tecnol. Pós-Colheita, Univ. Estadual Campinas, Fac. Eng. Agríc., Campinas-SP, Brazil, 2001Dussán-Sarria S., Honório S.L., Condutividade e difusividade térmica do figo (Ficus carica L.) 'Roxo de Valinhos', Rev. Bras. de Eng. Agríc. 24 (2004) 185-194Mohsenin, N.N., (1980) Thermal properties of foods and agricultural materials, Gordon Breach Sci, pp. 198-224. , Publ, New York, USAGoyette, B., Vigneault, C., Panneton, B., Raghavan, G.S.V., Method to evaluate temperature at the surface of horticultural crops (1997) Can. Agric. Eng, 38, pp. 292-295(1998) Methods of precooling fruits, vegetables and ornamentals, Am, pp. 14.1-14.10. , Soc. Heat. Refrig. Air-Cond. Eng, ASHRAE, Refrigeration handbook Inc, Atlanta, Georgia, USA, AnonTeruel M.B., Estudo teórico - experimental do resfriamento de laranja e banana com ar forçado, Univ. Estadual Campinas, Fac. Eng. Mec.,Thesis, Campinas, Brazil, 2000, 300 pDincer, I., Cooling parameters and film conductances of spherical products cooled in an airflow (1995) Appl. Energy, 50, pp. 269-280Dincer, I., Simplified solution for temperature distributions of spherical and cylindrical products during rapid air cooling (1995) Energy Convers. Manag, 36, pp. 1175-1184Baird, C.D., Gaffney, J.J., Talbot, M.T., Design criteria for efficient and cost effective forced-air cooling systems for fruits and vegetables (1988) ASHRAE Trans, 94, pp. 1434-145

Anomalous water and ion dynamics in hydroxyapatite mesopores

International audienc

The heme-based oxygen sensor Rhizobium etli FixL: influence of auxiliary ligands on heme redox potential and implications on the enzyme activity

Conformational changes associated to sensing mechanisms of heme-based protein sensors are a key molecular event that seems to modulate not only the protein activity but also the potential of the Fe redox couple of the heme domain. In this work, midpoint potentials (E) assigned to the Fe redox couple of the heme domain of FixL from Rhizobium etli (ReFixL) in the unliganded and liganded states were determined by spectroelectrochemistry in the presence of inorganic mediators. In comparison to the unliganded ReFixL protein (+ 19 mV), the binding to ligands that switch off the kinase activity induces a negative shift, i. e. E = − 51, − 57 and − 156 mV for O, imidazole and CN, respectively. Upon binding to CO, which does not affect the kinase active, E was observed at + 21 mV. The potential values observed for Fe of the heme domain of ReFixL upon binding to CO and O do not follow the expected trend based on thermodynamics, assuming that positive potential shift would be expected for ligands that bind to and therefore stabilize the Fe state. Our results suggest that the conformational changes that switch off kinase activity upon O binding have knock-on effects to the local environment of the heme, such as solvent rearrangement, destabilize the Fe state and counterbalances the Fe-stabilizing influence of the O ligand

Existencia de una estructura ?ptima de capital

El presente trabajo de tesis busca presentar expresiones matem?ticas para el costo del capital accionario (RS) y costo de la deuda (RB) que permitan verificar y calcular anal?ticamente la existencia (o inexistencia) de la estructura ?ptima de capital utilizando el modelo del WACC, y teniendo como base las teor?as de Modigliani y Miller y del Trade-Off. En caso que se pueda determinar la estructura ?ptima de capital, esta debe calcularse en funci?n de otras variables, sin que el valor de ninguna de ellas sea asumido arbitrariamente. Las caracter?sticas principales del presente trabajo incluyen: a) Presentar expresiones matem?ticas para RS y RB que permitan la existencia y el c?lculo de una estructura ?ptima de capital. b) Presentar una formulaci?n de RB que aumente con el nivel de apalancamiento, reflejando de esta forma el impacto de los costos de quiebra en el costo de la deuda. Asimismo, la expresi?n de RB debe tener un valor mayor a cero cuando no exista deuda. c) Las expresiones que se elijan no deben permitir que el apalancamiento ?ptimo se encuentre limitado. Esto debido a que, en la realidad, el nivel de apalancamiento es muy variado dependiendo de las empresas, industrias y mercados donde funcionan

Efecto de un anticoccidial natural a base de saponinas de Yucca schidigera y Trigonella foenum-graecum sobre el control de coccidiosis en pollos de carne

The aim of this study was to evaluate the effect of a natural anticoccidial based on saponins from Yucca schidigera and Trigonella foenum-graecumen in the control of coccidiosis in broilers. It was used 75 1-day-old chicks from the Cobb 500 line, randomly distributed in three treatments: DBSA (base diet without addition of anticoccidial), DBAN (base diet with addition of natural anticoccidial), DBQI (base diet with addition of chemical anticoccidial - ionophore) with five repetitions and five chicks per experimental unit. The birds were inoculated on day 14 with 15 times the recommended dose of the live vaccine (Coccivac-D) which contains Eimeria acervulina, E. maxima, E. mivati, E. tenella, E. necatrix, E. brunetti, E. hagani and E. praecox to induce the disease. The variables oocyst count per gram of faeces (ROpgh), intestinal lesions and various productive parameters were evaluated. The values ​​of ROpgh were similar for DBAN and DBQI peaking at the seventh week (328.8 and 455.8 Opgh, respectively), and then decreasing. Intestinal lesions on days 10, 20 and 28 post-infection and the productive parameters at the end of the study were similar for both treatments, but significantly better than the DBSA control. It is concluded that the saponins from Y. schidigera and T. foenum-graecum can efficiently replace chemical anticoccidials in bird feeds.  El objetivo del estudio fue evaluar el efecto de un anticoccidial natural a base de saponinas procedentes de Yucca schidigera y Trigonella foenum-graecumen en el control de coccidiosis en pollos de carne. Se utilizaron 75 pollos machos de la línea Cobb 500 de un día de edad, distribuidos al azar en tres tratamientos: DBSA (dieta base sin adición de anticoccidial), DBAN (dieta base con adición de anticoccidial natural), DBQI (dieta base con adición de anticoccidial químico - ionóforo) con cinco repeticiones y cinco aves por unidad experimental. Los pollos fueron inoculados en día 14 con 15 veces la dosis recomendada de la vacuna viva (Coccivac-D), que contiene Eimeria acervulina, E. maxima, E. mivati, E. tenella, E. necatrix, E. brunetti, E. hagani y E. praecox para inducir la enfermedad. Se evaluaron las variables recuento de ooquistes por gramo de heces (ROpgh), lesiones intestinales y diversos parámetros productivos. Los valores de ROpgh fueron similares para DBAN y DBQI llegando a su pico a la séptima semana (328.8 y 455.8 Opgh, respectivamente), para luego disminuir. Las lesiones intestinales los días 10, 20 y 28 pos-infección y los parámetros productivos al final del estudio fueron similares para ambos tratamientos, pero significativamente mejores que el control DBSA. Se concluye que las saponinas procedentes de Y. schidigera y T. foenum-graecum pueden remplazar eficientemente a los anticoccidiales químicos en la alimentación de las aves

Treatment of children obesity and diabetes through gamification

Childhood obesity is nowadays a global epidemic. This illness sometimes comes with another associated problem, like Diabetes type II. In this paper we present a case of study about the results of the application of a gamified educational program. A 3-year longitudinal and prospective study was conducted a patient with obesity and diabetes. Different assessments regarding the health state of the patient have been developed (family background, physical/medical, emotional state and physical activity). Using Positive outcomes have been obtained in their medical registers and also, in their health habits. Thus, the application of gamification strategies in the educational program has positive impact in the health

The three-peat challenge : business as usual, responsible agriculture, and conservation and restoration as management trajectories in global peatlands

FundingThis work was supported by the Natural Environment Research Council [grant numbers NE/X015238/1; NE/ V006444/1; NE/V018760/1], the Royal Geographical Society (RBEA 02.21), the Royal Society (RGS\R2\202229), and Growing Health (BB/X010953/1) BBSRC Institute Strategic Programme.Peer reviewedPublisher PD