Strategic manipulation of empirical tests

Theories can be produced by individuals seeking a good reputation of knowledge. Hence, a significant question is how to test theories anticipating that they might have been produced by (potentially uninformed) experts who prefer their theories not to be rejected. If a theory that predicts exactly like the data generating process is not rejected with high probability then the test is said to not reject the truth. On the other hand, if a false expert, with no knowledge over the data generating process, can strategically select theories that will not be rejected then the test can be ignorantly passed. These tests have limited use because they cannot feasibly dismiss completely uninformed experts. Many tests proposed in the literature (e.g., calibration tests) can be ignorantly passed. Dekel and Feinberg (2006) introduced a class of tests that seemingly have some power of dismissing uninformed experts. We show that some tests from their class can also be ignorantly passed. One of those tests, however, does not reject the truth and cannot be ignorantly passed. Thus, this empirical test can dismiss false experts.We also show that a false reputation of knowledge can be strategically sustained for an arbitrary, but given, number of periods, no matted which test is used (provided that it does not reject the truth). However, false experts can be discredited, even with bounded data sets, if the domain of permissible theories is mildly restricted.

Optimal two-sided tests for instrumental variables regression with heteroskedastic and autocorrelated errors

This paper considers two-sided tests for the parameter of an endogenous variable in an instrumental variable (IV) model with heteroskedastic and autocorrelated errors. We develop the nite-sample theory of weighted-average power (WAP) tests with normal errors and a known long-run variance. We introduce two weights which are invariant to orthogonal transformations of the instruments; e.g., changing the order in which the instruments appear. While tests using the MM1 weight can be severely biased, optimal tests based on the MM2 weight are naturally two-sided when errors are homoskedastic. We propose two boundary conditions that yield two-sided tests whether errors are homoskedastic or not. The locally unbiased (LU) condition is related to the power around the null hypothesis and is a weaker requirement than unbiasedness. The strongly unbiased (SU) condition is more restrictive than LU, but the associated WAP tests are easier to implement. Several tests are SU in nite samples or asymptotically, including tests robust to weak IV (such as the Anderson-Rubin, score, conditional quasi-likelihood ratio, and I. Andrews' (2015) PI-CLC tests) and two-sided tests which are optimal when the sample size is large and instruments are strong. We refer to the WAP-SU tests based on our weights as MM1-SU and MM2-SU tests. Dropping the restrictive assumptions of normality and known variance, the theory is shown to remain valid at the cost of asymptotic approximations. The MM2-SU test is optimal under the strong IV asymptotics, and outperforms other existing tests under the weak IV asymptotics.

Invariant tests in an instrumental variables model with unknown data generating process

In this work we focus on tests for the parameter of an endogenous variable in a weakly identi ed instrumental variable regressionmodel. We propose a new unbiasedness restriction for weighted average power (WAP) tests introduced by Moreira and Moreira (2013). This new boundary condition is motivated by the score e ciency under strong identi cation. It allows reducing computational costs of WAP tests by replacing the strongly unbiased condition. This latter restriction imposes, under the null hypothesis, the test to be uncorrelated to a given statistic with dimension given by the number of instruments. The new proposed boundary condition only imposes the test to be uncorrelated to a linear combination of the statistic. WAP tests under both restrictions to perform similarly numerically. We apply the di erent tests discussed to an empirical example. Using data from Yogo (2004), we assess the e ect of weak instruments on the estimation of the elasticity of inter-temporal substitution of a CCAPM model.

Utilização de nanosílica como aditivo estendedor para pastas cimentantes de baixa densidade destinadas à cimentação de poços petrolíferos

Cementing operations are conducted at different times of the well s life and they have high importance, because the functions are fundamental to keep good properties during a long life of the well, such as, maintain the mechanical stability of the well, to promote the isolation hydraulic and support the tubing. In some situations, the rocky zones have low fractures pressures and require the use of lightweight slurries to prevent the hydrostatic pressure in the formation is greater than the pressure of fracture. There are three ways to reduce the density of cement slurries: exterders water additives, microspheres and foamed slurries. The most used extender water additive is sodium bentonite, which is a clay with a good capacity of water absorption and expansion of its volume, the main disadvantage of this additive is the reduction of the strength. Currently, the use of nanoscale particles has received special attention, mainly because they get new functionalities. Following this trend, this paper aims to use a colloidal solution of nano-silica as an exterders water additives for use in oil wells. Slurries were designed with fixed 13lb/gal density and concentration of nano silica 0.1 gpc; 0.4 gpc; 0.7 and 1gpc, the influence of nano-silica was studied at these levels in isolation and combined varying concentrations of CaCl2,. Tests including rheology, stability, strength, thickening time, porosity and permeability. Besides the API tests, microstructural characterizations were performed after 28 days of the slurries, X-ray diffraction (XRD) and scanning electron microscopy (SEM)

Pycnoscelus surinamensis (Linnaeus, 1758) (Blaberoidea: Blaberidae), a cockroach with a possible association with the ant Brachymyrmex cordemoyi Forel, 1895 (Hymenoptera: Formicidae) and which may be exhibiting a domiciliation trend.

In the present paper, we report on the occurrence of the cockroach Pycnoscelus surinamensis (Linnaeus, 1758) in Brachymyrmex cordemoyi Forel, 1895 nests, indicating a possible symbiosis between these two species. Also, the finding of intradomicile P. surinamensis nymphs may indicate this species is extending its habitat to human habitations, i.e. changing its ecological category from peridomestic to domestic.

Minimizing inter-genotypic competition effects to predict genetic values and selection in forestry genetic tests

The effect of competition is an important source of variation in breeding experiments. This study aimed to compare the selection of plants of open-pollinated families of Eucalyptus with and without the use of competition covariables. Genetic values were determined for each family and tree and for the traits height, diameter at breast height and timber volume in a randomized block design, resulting in the variance components, genetic parameters, selection gains, effective size and selection coincidence, with and without the use of covariables. Intergenotypic competition is an important factor of environmental variation. The use of competition covariables generally reduces the estimates of variance components and influences genetic gains in the studied traits. Intergenotypic competition biases the selection of open-pollinated eucalypt progenies, and can result in an erroneous choice of superior genotypes; the inclusion of covariables in the model reduces this influence.

The intravenous glucose tolerance and postprandial glucose tests may present different responses in the evaluation of obese dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Utilização de modelos de regressão aleatória para produção de leite no dia do controle, com diferentes estruturas de variâncias residuais

Foram utilizados quatorze modelos de regressão aleatória, para ajustar 86.598 dados de produção de leite no dia do controle de 2.155 primeiras lactações de vacas Caracu, truncadas aos 305 dias. Os modelos incluíram os efeitos fixos de grupo contemporâneo e a covariável idade da vaca ao parto. Uma regressão ortogonal de ordem cúbica foi usada para modelar a trajetória média da população. Os efeitos genéticos aditivos e de ambiente permanente foram modelados por meio de regressões aleatórias, usando polinômios ortogonais de Legendre, de ordens cúbicas. Diferentes estruturas de variâncias residuais foram testadas e consideradas por meio de classes contendo 1, 10, 15 e 43 variâncias residuais e de funções de variâncias (FV) usando polinômios ordinários e ortogonais, cujas ordens variaram de quadrática até sêxtupla. Os modelos foram comparados usando o teste da razão de verossimilhança, o Critério de Informação de Akaike e o Critério de Informação Bayesiano de Schwar. Os testes indicaram que, quanto maior a ordem da função de variâncias, melhor o ajuste. Dos polinômios ordinários, a função de sexta ordem foi superior. Os modelos com classes de variâncias residuais foram aparentemente superiores àqueles com funções de variância. O modelo com homogeneidade de variâncias foi inadequado. O modelo com 15 classes heterogêneas foi o que melhor ajustou às variâncias residuais, entretanto, os parâmetros genéticos estimados foram muito próximos para os modelos com 10, 15 ou 43 classes de variâncias ou com FV de sexta ordem.

Sistema híbrido para detecção e diagnóstico de falhas em sistemas dinâmicos

The industries are getting more and more rigorous, when security is in question, no matter is to avoid financial damages due to accidents and low productivity, or when it s related to the environment protection. It was thinking about great world accidents around the world involving aircrafts and industrial process (nuclear, petrochemical and so on) that we decided to invest in systems that could detect fault and diagnosis (FDD) them. The FDD systems can avoid eventual fault helping man on the maintenance and exchange of defective equipments. Nowadays, the issues that involve detection, isolation, diagnose and the controlling of tolerance fault are gathering strength in the academic and industrial environment. It is based on this fact, in this work, we discuss the importance of techniques that can assist in the development of systems for Fault Detection and Diagnosis (FDD) and propose a hybrid method for FDD in dynamic systems. We present a brief history to contextualize the techniques used in working environments. The detection of fault in the proposed system is based on state observers in conjunction with other statistical techniques. The principal idea is to use the observer himself, in addition to serving as an analytical redundancy, in allowing the creation of a residue. This residue is used in FDD. A signature database assists in the identification of system faults, which based on the signatures derived from trend analysis of the residue signal and its difference, performs the classification of the faults based purely on a decision tree. This FDD system is tested and validated in two plants: a simulated plant with coupled tanks and didactic plant with industrial instrumentation. All collected results of those tests will be discussed

CHARACTERIZATION of RALSTONIA SOLANACEARUM STRAINS FROM BRAZIL USING MOLECULAR METHODS and PATHOGENICITY TESTS

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Didática do plurilinguismo: efeitos da intercompreensão de línguas românicas na compreensão de textos escritos em português

This exploratory study aims to present some readings as Doyé (2003), Carrasco Perea (2003), Melo Araújo e Sá (2004), Chavagne (2009) and Alas-Martins (2010; 2011) which helped to confirm some ways for showing that a plurilingual environment can enable a trend in improving the understanding of written texts in the mother tongue, and can collaborate on a better perception of the world around a person with all their different nuances. The study describes the methodology and some results of our doctoral research that resulted in the insertion of the experimental discipline called Intercomprehension of Romanic Languages (ILR) in the curriculum in the city of Natal / RN / Brazil, and it was justified because of high functional illiteracy degree among young people up to 15 years old according to the educational data from IBGE research on 2010. The results were verified through an experimental action-research which was characterized by Lewin (1946); Nunan (1992); Thiollent (1994) and Trip (2005) in two schools: Professoara Terezinha Paulino de Lima (municipal school) and Professora Ana Julia de Carvalho Mousinho (State of Rio Grande do Norte), with 95 students from the final years of primary education. The corpus of this research was subjected to a series of condensed techniques like the nonparametric test from Kruskal and Wallis (1952) and the parametric test ANOVA as an effort to provide statistical significance to the analysis of the results indicated in the book of ILR activities. The research presented some skill views about reading comprehension of written texts according to perspective of Ringbow (1987), Giacobbe (1990), Alarcão (1991; 2009a and 2009b), Corder (1992), Castellotti (2001) and Degache (2003), and the possibilities of transfer these skills for learning Portuguese as pointed out by Meissner, Klein and Stegmann (2004); it indicates a positive trend towards the understanding of LM according to analyzing the scores of written tests and texts by participants in solving tasks

A duplicated nitrotienyl derivative with antimycobacterial activity: synthesis, X-ray crystallography, biological and mutagenic activity tests

A duplicated nitrotienyl derivative was obtained as a by-product from the synthesis of a proposed molecular hybrid of a nitrotienyl derivative and isoniazid with an expected dual antimycobacteria mechanism. The structure was shown to be the 5,5'-dinitro-2(2,3-diaza-4-(2'-tienyl)buta-1,3-dienyl)tiophene by X-ray crystallography. The minimal inhibitory concentration (MIC) determination of this compound proved to be promising against Mycobacterium pathogenic strains such as M. avium and M. kansasei, although it had a high level of mutagenicity, as observed in mutagenic activity tests. (c) 2006 Elsevier Masson SAS. All rights reserved.

Mathematical tests about the existence and applications of PPS-wavelets in function approximation problems

Neural networks and wavelet transform have been recently seen as attractive tools for developing eficient solutions for many real world problems in function approximation. Function approximation is a very important task in environments where computation has to be based on extracting information from data samples in real world processes. So, mathematical model is a very important tool to guarantee the development of the neural network area. In this article we will introduce one series of mathematical demonstrations that guarantee the wavelets properties for the PPS functions. As application, we will show the use of PPS-wavelets in pattern recognition problems of handwritten digit through function approximation techniques.

Prevalência e susceptibilidade antimicrobiana de Staphylococcusspp. em quadros de saúde e doença periodontal

The aim of this study was determine the prevalence and antimicrobial susceptibility of Staphylococcus spp. from patients with periodontal disease and periodontally healthy, correlate them with factors to host, local environment and traits of the diseases. To this, thirty adults from 19 to 55 years old were selected. They had not periodontal treatment and no antibiotic or antimicrobial was administered during three previous months. From these individuals, sites periodontally healthy, with chronic gingivitis and/or periodontitis were analyzed. Eighteen subgingival dental biofilm samples were collected through sterile paper points being six from each tooth randomly selected, representing conditions mentioned. They were transported to Oral Microbiology laboratory, plated onto Mannitol Salt Agar (MSA) and incubated at 370C in air for 48 h. Staphylococcus spp. were identified by colonial morphology, Gram stain, catalase reaction, susceptibility to bacitracin and coagulase activity. After identification, strains were submitted to the antibiotic susceptibility test with 12 antimicrobials, based on Kirby-Bauer technique. To establish the relation between coagulase-negative Staphylococcus (CSN) presence and their infection levels and host factors, local environment and traits of diseases were used Chi-square, Mann-Whitney and Kruskal-Wallis tests to a confidence level of 95%. 86,7% subjects harbored CSN in 11,7% periodontal sites. These prevalence were 12,1% in healthy sites, 11,7% in chronic gingivitis, 13,5% in slight chronic periodontitis, 6,75% in moderate chronic periodontitis and in sites with advance chronic periodontitis was not isolated CSN, without difference among them (p = 0,672). There was no significant difference to presence and infection levels of CSN as related to host factors, local environm ent and traits of the diseases. Amongst the 74 samples of CSN isolated, the biggest resistance was observed to penicillin (55,4%), erythromycin (32,4%), tetracycline (12,16%) and clindamycin (9,4%). 5,3% of the isolates were resistant to oxacilin and methicillin. No resistance was observed to ciprofloxacin, rifampicin and vancomycin. It was concluded that staphylococci are found in low numbers in healthy or sick periodontal sites in a similar ratio. However, a trend was observed to a reduction in staphylococci occurrence toward more advanced stages of the disease. This low prevalence was not related to any variables analyzed. Susceptibility profile to antibiotics demonstrates a raised resistance to penicillin and a low one to methicillin. To erythromycin, tetracycline and clindamycin was observed a significant resistance

Interpretation of Resistivity Piezocone Tests in a Contaminated Municipal Solid Waste Disposal Site

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)