The self-talk of a group of undergraduate students, both in general day-to-day and academic situations, was compiled and the effect on students' academic performances was analysed. The results show that: (1) there is a correlation between the valence of general self-talk and academic self-talk; (2) participants exhibit more positive than negative self-talk, although they report more negative self-talk when faced with a more difficult compared to an easier academic subject, while positive academic self-talk was higher in the easy than in the more difficult academic subjects; (3) the negative valence of self-talk (general and academic), is correlated with the negative results predicted by the students six weeks before doing the examination and (4) for the difficult academic subject, but nor for easier subject, students who suspend report using less positive academic self-talk and more negative academic self-talk than those who passes. These results to encourage for wondering about the utility of training in the use of appropriate self-talk for coping academic situations perceived as difficult and improve students performance in such situations.

En este trabajo se identificaron los autodiálogos de un grupo de estudiantes en situaciones cotidianas y en situaciones académicas de evaluación. Posteriormente, se analizó la relación entre los autodiálogos y el rendimiento académico. Los resultados muestran que: (1) existe correlación entre las valencias del autodiálogo general y el autodiálogo académico; (2) los participantes muestran más autodiálogo positivo que negativo, tanto en su vida cotidiana como en situaciones académicas. En relación a estas últimas, los participantes informan más autodiálogo negativo y menos autodiálogo positivo ante la Evaluación de una materia académica percibida como difícil que ante una percibida como fácil; (3) la valencia negativa de los autodiálogos (general y académico) correlacionó con los resultados académicos negativos anticipados por los estudiantes seis semanas antes de realizar el exámen y (4) en el caso de la materia valorada como difícil, los resultados académicos obtenidos en el examen guardan una estrecha relación con el rendimiento anticipado. Encontramos en los resultados argumentos para reflexionar sobre la utilidad que podría tener el entrenamiento en el uso de autodiálogos adecuados para facilitar el afrontamiento de situaciones académicas percibidas como difíciles y mejorar el rendimiento de los estudiantes en tales situaciones.

Fractal scaling of the exponential type is used to establish the cumulative volume (V) distribution applied through agricultural spray nozzles in size x droplets, smaller than the characteristic size X. From exponent d, we deduced the fractal dimension (Df) which measures the degree of irregularity of the medium. This property is known as 'self-similarity'. Assuming that the droplet set from a spray nozzle is self-similar, the objectives of this study were to develop a methodology for calculating a Df factor associated with a given nozzle and to determine regression coefficients in order to predict droplet spectra factors from a nozzle, taking into account its own Df and pressure operating. Based on the iterated function system, we developed an algorithm to relate nozzle types to a particular value of Df. Four nozzles and five operating pressure droplet size characteristics were measured using a Phase Doppler Particle Analyser (PDPA). The data input consisted of droplet size spectra factors derived from these measurements. Estimated Df values showed dependence on nozzle type and independence of operating pressure. We developed an exponential model based on the Df to enable us to predict droplet size spectra factors. Significant coefficients of determination were found for the fitted model. This model could prove useful as a means of comparing the behavior of nozzles which only differ in not measurable geometric parameters and it can predict droplet spectra factors of a nozzle operating under different pressures from data measured only in extreme work pressures.

Knodus shinahota, espécie nova, é descrita do río Shinahota, um afluente do alto da bacia do rio Mamoré, Província de Tiraque, Estado de Cochabamba, Bolívia. A espécie nova pode ser distinguida de todas as suas congêneres exceto K. chapadae e K. geryi por ter seis fileiras de escamas entre a linha lateral e a origem da nadadeira dorsal (vs 4 ou 5 fileiras de escamas nas demais espécies). Knodus shinahota difere de K. chapadae por possuir mais fileiras de escamas entre a linha lateral e a origem da nadadeira pélvica (5 vs 3½ ou 4, respectivamente) e mais escamas na linha lateral (38-41 vs 36-38, respectivamente). Difere de K. geryi por possuir mais fileiras de escamas entre a linha lateral e a origem da nadadeira pélvica (5 vs 4, respectivamente); menos raios ramificados na nadadeira anal (17-20 vs 15-17, respectivamente), e pela falta das duas grandes manchas escuras, simétricas, basalmente nos lobos da nadadeira caudal que caracteriza K. geryi.

Knodus shinahota, new species, is described from río Shinahota, a tributary of the upper rio Mamoré basin, Província de Tiraque, Cochabamba State, Bolivia. The new species can be distinguished from all congeners except K. chapadae and K. geryi by having six rows of scales between the lateral line and the dorsal-fin origin (vs 4 or 5 rows of scales in the other species). Knodus shinahota differs from K. chapadae by possessing more rows of scales between the lateral line and the pelvic-fin origin (5 vs 3½ or 4, respectively) and more lateral line scales (38-41 vs 36-38, respectively). It differs from K. geryi by possessing more rows of scales between the lateral-line and the pelvic-fin origin (5 vs 4, respectively); fewer branched anal-fin rays (17-20 vs 15-17, respectively), and by lacking the two symmetric, large, dark, blotches on the basal portions of the caudal-fin lobes that characterize K. geryi.