[History, effects and mechanisms of action of ecstasy (3,4-methylenedioxyamphetamine): review of the literature]. / Histórico, efeitos e mecanismo de ação do êxtase (3-4 metilenodioximetanfetamina): revisão da literatura.

This review focuses on 3,4-methylenedioxymethamphetamine, an illegal drug known as "ecstasy." Ecstasy was introduced in Brazil in 1994. Data are lacking on the epidemiology and usage pattern of the drug in Brazil. However, there is evidence that until now the use of ecstasy has been limited to middle-class or upper-middle-class youth, so that most people, including health care professionals, are unfamiliar with the drug. However, ecstasy may be becoming more popular in Brazil, following a pattern seen in North America and Europe. Possible contributing to the drug's popularity is the fact that ecstasy is sold as a pill and is thus extremely easy to use. Ecstasy has a reputation for not being physically dangerous; however, there are many reports of adverse reactions associated with the drug. In addition, it is known that not all pills sold as ecstasy actually contain methylenedioxymethamphetamine. Since there is no quality control for the pills' contents, users never know exactly what they are taking. Thus, although users may perceive the effects of the drug as mostly positive, ecstasy is potentially dangerous. Primary and secondary interventions are needed to prevent the use of ecstasy and the occurrence of adverse reactions. To be effective, these measures must take into consideration the characteristics of the user population and the usage patterns. It is also essential to prepare health professionals for emergency medical interventions in cases of intoxication and complications resulting from the use of ecstasy.

Patterns of marihuana smoking among Brazilian students.

Changes in frequency of marihuana smoking over time were investigated by interviewing forty-seven Brazilian students from São Paulo between 18 and 24 years old, of both sexes. From their report, it was concluded that the course of smoking frequency follows two predominant patterns. In one of them, the 'Stable Pattern', subjects report increasing consumption up to a peak frequency where they remain for a relatively long and stable period of time. In the other one, the 'Descending Pattern', subjects report a gradual increase up to a peak, followed by a clear decline in rate of use. Two other patterns were also detected in a small number of subjects. The diversity of patterns identified stresses the difficulty in predicting the course of marihuana smoking frequency by young people. The relationship between marihuana smoking and the use of other drugs was also investigated. The only drugs that were reported to be regularly consumed by the majority of subjects were alcohol and tobacco, while 90% of the subjects reported having tried at least one other illegal drug.

Surface inspection via projection interferometry.

Projection fringe interferometry provides a useful technique for nondestructive surface analysis. Two beam interferometric fringes were projected onto a block of aluminum whose surface had various types of grooves cut into it. The fringes were digitized and analyzed via an automatic fringe tracking algorithm. Three-dimensional topographical maps of the surface's microstructure are presented together with a statistical analysis of surface parameters including average roughness, height distributions, and the autocorrelation function.

Optical Fourier transform characterization of fish scale age.

Optical Fourier transforms of haddock fish scales were made for fish taken from two different bodies of water. The scales in each group varied in age from 2 to 10 yr. A comparison of the image processed digitized Fourier transforms for the scales was made on a personal computer. Statistical correlation studies of these transforms were performed, and the results show a fairly good age discrimination between the scales in each age group.

Thermally induced laser interference and birefringence in a metal-coated optical plate.

Time-dependent interference and stress birefringent patterns have been observed when a laser beam was incident upon a metal-coated optical plate (beam splitter). These effects are caused by the spatially nonuniform and time-dependent temperature distribution in the plate as the result of the laser-light absorption. A detailed description of the observed phenomena is presented.

Rotational matched spatial filter for biological pattern recognition.

Randomly oriented microbiological patterns are recognized by rotating a matched spatial filter with an optical wedge prism. The filter is made from a composite input pattern with various sized objects to cover wider ranges of size variation in a species to be identified.

Coherent spatial filtering with simulated input.

A disadvantage of a well-tuned matched filter is partly overcome in recognizing biological species, i.e., algae. A simplified input pattern is prepared which simulates a given species. The matched spatial filter for this pattern can identify various diatoms in the species with considerably less size and orientation dependence. In addition, the filter still retains a high degree of pattern discrimination against other species.

Fourier transform differences and averaged similarities in diatoms.

Phase contrast photographs of diatoms are characterized from their Fourier transform taken through an optical diffractometer. The system output is placed on line to a PDP11/40 providing digital subtraction of two output spectral distributions due to different species. Differences obtained in this manner are used for characterizing various species. An average Fourier transform taken through coherent additions is also analyzed to find common features in a given set of diatoms.

Multispectral size-averaged incoherent spatial filtering.

A method of 2-D size-averaged incoherent recognition filtering is described. White light input illumination is used to multiplex chromatically a continuum of inputs differing in their spatial Fourier spectral magnifications. A two-grating dichromated-gelatin lateral-dispersion compensating device is inserted to correct chromatic dispersion introduced by a computer-generated hologram filter. The resulting registered recognition patterns are added to form a single effective filter size-averaged recognition peak. Using high efficiency compensating gratings and a bleached binary hologram allow the use of a relatively low-power light source.

Water pollution monitoring using matched spatial filters.

Presented are some results obtained from the application of matched spatial filtering techniques to the identification of biological specimens called diatoms (i.e., water algae). A prototype semiautomatic optical processor has been developed that utilizes the Vander Lugt type complex spatial filters. We describe the optical filter averaging technique employed and discuss our semi in situ developing method for the filters. The advantage of this method with regards to the critical position requirements for time sharing optical filters is also presented. The filter holder is mounted on X, Y stages and precision positioned under the control of a PDP-11-40 computer.

The dipole model and phase transitions in biological membranes.

Assuming the dipole model for a membrane, approximate calculations are made which employ a dipole-dipole interaction energy. The calculations are based upon the assumption of cooperative coupling of membrane polar molecules and make use of the Bragg-Williams approximation. A theoretical estimate is made of the critical temperature at which phase changes might occur in certain biological membranes. Proposals are presented which explain how the dipole transition might relate to the sometimes observed thermal phase transitions in biological membranes.