Due to a combination of their promising anticancer properties, limited supply from the marine sponge source and their unprecedented molecular architecture, spirastrellolides represent attractive and challenging synthetic targets. A modular strategy for the synthesis of spirastrellolide A methyl ester, which allowed for the initial stereochemical uncertainties in the assigned structure was adopt...

This paper analyzes the individual decision of online shopping, in terms of socioeconomic characteristics, internet related variables and location factors. Since online shopping is only observed for internet users, we use the two-step Heckman’s model to correct sample selection. We argue that one of the relevant variables to explain online shopping, the existence of a home internet connection, ...

Social learning models of investment provide an interesting explanation for sudden changes in investment behaviour. Caplin and Leahy (1994) develop a model of social learning in which agents learn about the true state of demand from the investment suspension decisions of other agents. The author tests the main predictions of Caplin and Leahy’s model using a unique database of investment project...

This paper uses Italian panel data to analyse transition probabilities at the bottom of the earnings distribution during the 1990s. The analytical framework is characterised by the ability to account for endogeneity of initial conditions and earnings attrition. Results show that both are endogenous for the estimation of low pay transitions. In particular it is found that the low paid are more l...

Businesses routinely rely on econometric models to analyze and predict consumer behavior. Estimation of such models may require combining a firm’s internal data with external datasets to take into account sample selection, missing observations, omitted variables and errors in measurement within the existing data source. In this paper we point out that these data problems can be addressed when e...

This paper considers the problem of testing for cross section independence in limited dependent variable panel data models. It derives a Lagrangian multiplier (LM) test and shows that in terms of generalized residuals of Gourieroux, Monfort, Renault and Trognon (1987) it reduces to the LM test of Breusch and Pagan (1980). Due to the tendency of the LM test to over-reject in panels with large N ...

An Economic Analysis of Exclusion Restrictions for Instrumental Variable Estimation Instrumental variable estimation requires untestable exclusion restrictions. With policy effects on individual outcomes, there is typically a time interval between the moment the agent realizes that he may be exposed to the policy and the actual exposure or the announcement of the actual treatment status. In suc...

Polycyclic aromatic hydrocarbons (PAHs) and n-alkanes are important specific organic constituents in fine particulate matter (PM2.5). Seventy-five PM2.5 samples were collected Spring Changzhou, to investigate the concentrations sources of (C9–C40) PAHs. The average total PAHs (∑PAHs) (∑n-alkanes) 4.37 ± 4.95 ng/m3 252.37 184.02 ng/m3, ranging from 0.43 22.22 57.37 972.17 respectively. ∑n-alkane...

A generalized concept in the Citrus genus is that highly polyembryonic varieties produce only a small number of hybrids. Small zygotic embryos congregate primarily near micropyle, while nucellar organize or away from micropyle. In present study, authors determined seeds, per seed, and largest embryo (LE) position five citrus cultivars: C35 citrange, Volkamer lemon, Amblycarpa mandarin, Minneola...

An efficient and accurate method for concrete thermal parameter inversion is essential to guarantee the reliable prompt analysis results of dams. Traditional methods either suffer from low efficiency or are limited in accuracy. Thus, this paper presents a multiple based on an integrated surrogate model (ISM) Jaya algorithm. This replaces finite element with ISM incorporating three machine learn...