Cassipourol: un diterpenoide monocíclico con actividad larvicida en Croton funckianus / Cassipourol: a monocyclic diterpenoid with larvicidal activity from Croton funckianus

Bioassay-guided fractionation of petroleum ether soluble part of the ethanolic extract of Croton funckianus (Euphorbiaceae: Crotonoideae) senescent leaves against Culex quinquefasciatus third instar larvae afforded a diterpenoid with Larvicidal activity called cassipourol. The structure of cassipourol was elucidated by 1D (1H, 13C) and 2D (COSY, HMQC, HMBC) NMR spectroscopy and by comparing their spectroscopic data with that reported in the literature.

El fraccionamiento guiado por bioensayos de la fracción soluble en éter de petróleo del extracto etanólico proveniente de las hojas senescentes de la especie Croton funckianus (Euphorbiaceae: Crotonoideae) frente a larvas de tercer estadio del mosquito zancudo Culex quinquefasciatus condujo a la identificación de un nuevo diterpenoide con actividad larvicida denominado cassipourol. La estructura del cassipourol se elucido empleando espectroscopia RMN 1D (1H, 13C) y 2D (COSY, HMQC, HMBC) y por comparación de sus datos espectroscópicos con los reportados en la literatura.

Illusion of control in Internet users and college students.

When people try to obtain a desired event and this outcome occurs independently of their behavior, they often think that they are controlling its occurrence. This is known as the illusion of control, and it is the basis for most superstitions and pseudosciences. However, most experiments demonstrating this effect had been conducted many years ago and almost always in the controlled environment of the psychology laboratory and with psychology students as subjects. Here, we explore the generality of this effect and show that it is still today a robust phenomenon that can be observed even in the context of a very simple computer program that users try to control (and believe that they are controlling) over the Internet. Understanding how robust and general this effect is, is a first step towards eradicating irrational and pseudoscientific thinking.

Frequency of judgment as a context-like determinant of predictive judgments.

Several studies have shown that predictive and causal judgments vary depending on whether the question used to assess the relationship between events is presented after each piece of information or only after all the available information has been observed. This effect could be understood by assuming that in the two cases people perceive that the test question requires that different sets of evidence be taken into account. This hypothesis is tested in the present experiments through contextual manipulations that take place at the time of training and at the time of test. Our results show that people use this contextual information to infer which set of events should be considered when making their subjective assessments. The results are at odds with current theoretical approaches, but it is possible to develop mechanisms that would allow these models to account for the observed evidence.

Flexible use of recent information in causal and predictive judgments.

Associative and statistical theories of causal and predictive learning make opposite predictions for situations in which the most recent information contradicts the information provided by older trials (e.g., acquisition followed by extinction). Associative theories predict that people will rely on the most recent information to best adapt their behavior to the changing environment. Statistical theories predict that people will integrate what they have learned in the two phases. The results of this study showed one or the other effect as a function of response mode (trial by trial vs. global), type of question (contiguity, causality, or predictiveness), and postacquisition instructions. That is, participants are able to give either an integrative judgment, or a judgment that relies on recent information as a function of test demands. The authors concluded that any model must allow for flexible use of information once it has been acquired.