Detection and estimation of block structure in spatial weight matrix

In many economic applications, it is often of interest to categorize, classify or label individuals by groups based on similarity of observed behavior. We propose a method that captures group affiliation or, equivalently, estimates the block structure of a neighboring matrix embedded in a Spatial Econometric model. The main results of the LASSO estimator shows that off-diagonal block elements are estimated as zeros with high probability, property defined as “zero-block consistency”. Furthermore, we present and prove zero-block consistency for the estimated spatial weight matrix even under a thin margin of interaction between groups. The tool developed in this paper can be used as a verification of block structure by applied researchers, or as an exploration tool for estimating unknown block structures. We analyzed the US Senate voting data and correctly identified blocks based on party affiliations. Simulations also show that the method performs well

Estimation and selection of spatial weight matrix in a spatial lag model

Spatial econometric models allow for interactions among variables through the specification of a spatial weight matrix. Practitioners often face the risk of misspecification of such a matrix. In many problems a number of potential specifications exist, such as geographic distances, or various economic quantities among variables. We propose estimating the best linear combination of these specifications, added with a potentially sparse adjustment matrix. The coefficients in the linear combination, together with the sparse adjustment matrix, are subjected to variable selection through the adaptive Least Absolute Shrinkage and Selection Operator (LASSO). As a special case, if no spatial weight matrices are specified, the sparse adjustment matrix becomes a sparse spatial weight matrix estimator of our model. Our method can therefore be seen as a unified framework for the estimation and selection of a spatial weight matrix. The rate of convergence of all proposed estimators are determined when the number of time series variables can grow faster than the number of time points for data, while Oracle properties for all penalized estimators are presented. Simulations and an application to stocks data confirms the good performance of our procedure

Correlações genéticas e fenotípicas em duas populações de milho (Zea mays L.) braquítico e suas implicações no melhoramento do teor de óleo no grão

Coeficientes de correlações genéticas e fenotípicas foram estimados entre os caracteres: altura da planta (AP); altura da espiga (AE); peso de espigas (PE) e teor de óleo (TO). As estimativas foram obtidas para duas populações braquíticas de milho (Piranão VD-2 e Piranão VF-1), baseado em espiga por fileira, utilizando-se testemunha intercalar, onde a cada duas progênies plantava-se uma fileira do híbrido simples AG 305-B. Os valores das correlações genéticas aditivas encontradas entre os caracteres altura da planta, altura da espiga e peso de espigas, foram todos positivos. Para o caráter teor de óleo, quando correlacionado com os demais caracteres, os valores das correlações obtidos foram negativos nas duas populações, exceção feita ao peso de espiga correlacionada com teor de óleo, na população Piranão VD-2, cujo valor foi positivo e próximo de zero. As respostas correlacionadas obtidas entre os caracteres, quando a seleção é praticada para o caráter teor de óleo e vice versa, independente do método de seleção empregado, mostram que a seleção para teor de óleo leva a modificação na estrutura da planta, para as duas populações.Genetic and phenotypic correlations were estimated among the characteristics: plant height (AP), ear height (AE), ear weight (PE) and oil content (TO). The estimates were obtained for two brachytic maize populations (Piranão VD-2 e Piranão VF-1), based on the ear to row having an intercalated tester where at each two progenie rows had one row of the single hybrid Ag-305-B used as a tester. The additive genetic correlations found between plant height, ear height and ear weight, were all positives. When the oil content was correlated with ear weight, plant and ear height, negative correlation values were observed in both populations, exception done for oil content and ear weight in the Piranão VD-2 population, which value was positive and near to zero. The correlated genetic response found are suggesting that when selection is done for oil content, in both population will have some changing with the plant phenotype, mainly for plant and ear height

INFLUENCE OF DIFFERENT ASSEMBLIES ON PRE-HEATING THE HSLA SAR 80T STEEL ON COATED ELECTRODE WELDING

The present work evaluated the influence of assemblies other than preheating in the welding process obtained by coated electrode, using high strength and low alloy steel SAR 80T as the base metal and the AWS E7018 electrode as the addition metal. In order to prevent cracks, preheating and interpassing for low alloy steel was performed. Depending on the way the preheating equipment is installed, it may take more or less time to reach the preheat temperature. Different assembly arrangements for top joints were evaluated, aiming at cost reduction, in addition to evaluations of the mechanical properties of the joint. Visual testing, ultrasound, micrography, macrography and cross-sectional traction were performed. The results obtained were considered acceptable and showed that there was an influence on time, cost of preheating and resistance to impact

Antimycobacterial And Cytotoxicity Activities Of Free And Liposome-encapsulated 3-(4'-bromo[1,1'-biphenyl-4-yl)-3-(4-bromo-phenyl)-n,n- Dimethyl-2-propen-1-amine

The antimycobacterial activity of 3-(4'-bromo[1,1'-biphenyl-4-yl)-3-(4- bromo-phenyl)-N,N-dimethyl-2-propen-1-amine (BBAP), free or incorporated in preformed liposomes, on extracellular M. tuberculosis H37Rv was 8 and 25 μM (MIC), respectively. Extracellular antimycobacterial activity was not significantly improved by entrapment of BBAP in liposomes, but there was a 6.1-fold reduction of BBAP cytotoxicity on J774 macrophages. Liposomal BBAP or its free form showed IC50 values of 165 and 27 μM, resulting in a selectivity index (SI=IC50/MIC) of 3.4 and 6.6, respectively. Free BBAP in concentrations from 10 to 80 μM were quite effective in eliminating intracellular M. tuberculosis while liposomal formulation was less effective at these concentrations.334871874Corbett, E.L., Watt, C.J., Walker, N., Mayer, D.B.M., Willians, B.G., Raviglione, M.C., Dye, C., (2003) Arch. Intern. Med., 163, p. 1009Vynnycky, E., Fine, P.E., (1997) Epidemiol. Infec., 119, p. 183Pandey, R., Khuller, G.K., (2005) J. Antimicrob. Chemother., 55, p. 430De Souza, A.O., Aily D., C.G., Sato, D.N., Durán, N., (1998) J. Antimicrob. Chemother., 42, p. 407De Souza, A.O., Junior, R.R.S., Ferreira-Julio, J.F., Rodriguez, J.A., Melo, P.S., Haun, M., Sato, D.N., Durán, N., (2001) Eur. J. Med. Chem., 36, p. 843De Souza, A.O., Pereira, D.G., Durán, N., (2002) Ann. Rev. Biomed. Sci., 4, p. 53De Souza, A.O., Hemerly, F.P., Busollo, A.C., Melo, P.S., Machado, G.M.C., Miranda, C.C., Santa-Rita, R.M., Durán, N., (2002) J. Antimicrob. Chemother., 50, p. 629De Souza, A.O., Santos, R.R., Sato, D.N., De Azevedo, M.M.M., Ferreira, D.A., Melo, P.S., Haun, M., Durán, N., (2004) J. Braz. Chem. Soc., 15, p. 682De Souza, A.O., Alderete, J.B., Faljoni-Alario, A., Silva, C.L., Durán, N., (2005) J. Chil. Chem. Soc., 50, p. 591De Conti, R., Gimenez, S.M.M., Haun, M., Pilli, R.A., De Castro, S.L., Durán, N., (1996) Eur. J. Med. Chem., 31, p. 915Bangham, A.D., Standish, M.M., Watkins, J.C., (1965) J. Mol. Biol., 13, p. 238Chen, P.S., Toribara, T.Y., Warner, H., (1956) Anal. Chem., 28, p. 1756Oh, Y.K., Nix, D.E., Straubinger, R.M., (1995) Antimicrob. Agents Chemother., 39, p. 2104Collins, L.A., Franzblau, S.G., (1997) Antimicrob. Agents Chemother., 41, p. 1004Denizot, F., Lang, R., (1986) J. Immun. Methods, 89, p. 27

Assembly of a Three-Dimensional Multitype Bronchiole Coculture Model Using Magnetic Levitation

A longstanding goal in biomedical research has been to create organotypic cocultures that faithfully represent native tissue environments. There is presently great interest in representative culture models of the lung, which is a particularly challenging tissue to recreate in vitro. This study used magnetic levitation in conjunction with magnetic nanoparticles as a means of creating an organized three-dimensional (3D) coculture of the bronchiole that sequentially layers cells in a manner similar to native tissue architecture. The 3D coculture model was assembled from four human cell types in the bronchiole: endothelial cells, smooth muscle cells (SMCs), fibroblasts, and epithelial cells (EpiCs). This study represents the first effort to combine these particular cell types into an organized bronchiole coculture. These cell layers were first cultured in 3D by magnetic levitation, and then manipulated into contact with a custom-made magnetic pen, and again cultured for 48 h. Hematoxylin and eosin staining of the resulting coculture showed four distinct layers within the 3D coculture. Immunohistochemistry confirmed the phenotype of each of the four cell types and showed organized extracellular matrix formation, particularly, with collagen type I. Positive stains for CD31, von Willebrand factor, smooth muscle a-actin, vimentin, and fibronectin demonstrate the maintenance of the phenotype for endothelial cells, SMCs, and fibroblasts. Positive stains for mucin-5AC, cytokeratin, and E-cadherin after 7 days with and without 1% fetal bovine serum showed that EpiCs maintained the phenotype and function. This study validates magnetic levitation as a method for the rapid creation of organized 3D cocultures that maintain the phenotype and induce extracellular matrix formation

Quasiparticle Interactions in Fractional Quantum Hall Systems: Justification of Different Hierarchy Schemes

The pseudopotentials describing the interactions of quasiparticles in fractional quantum Hall (FQH) states are studied. Rules for the identification of incompressible quantum fluid ground states are found, based upon the form of the pseudopotentials. States belonging to the Jain sequence nu=n/(1+2pn), where n and p are integers, appear to be the only incompressible states in the thermodynamic limit, although other FQH hierarchy states occur for finite size systems. This explains the success of the composite Fermion picture.Comment: RevTeX, 10 pages, 7 EPS figures, submitted fo Phys.Rev.