ABSTRACT
The different stages of the life cycle of parasites are important components of ecosystems. Changes in environmental conditions may affect free-living stages, host-parasite interactions and ecosystem functioning. The larvae of Chordodes nobilii, which belongs to the parasitic phylum Nematomorpha, are susceptible to extreme temperatures and different pollutants, but the effects of pH and moderate temperature variations have not been evaluated yet. Our objective was to assess the effect of temperature, pH and their interaction on the infectivity of C. nobilii larvae to Aedes aegypti larvae over time. Larvae were treated with factorial combinations of temperature (18, 23 and 28°C), pH (7, 8 and 9) and time periods (24 and 48 h). Results show a highly significant interaction among all variables. The highest infectivity was recorded at 18°C and pH 7 at 24 and 48 h, and the lowest one at 28°C and pH 8 at 24 and 48 h. Infectivity differed significantly among the three temperatures only at pH 8 and 48 h, decreasing with increasing temperature. Our study is the first report of the effect of pH on a Nematomorpha species and suggests that the infectivity of C. nobilii larvae may be affected negatively by an increase in temperature and its interaction with pH and time. Since parasites must be considered for a better understanding of the effects of stressors on freshwater ecosystems, our results may help in the design and analysis of studies of anthropogenic impact.
Subject(s)
Ecosystem , Helminths , Animals , Fresh Water , Larva , Life Cycle Stages , TemperatureABSTRACT
En continuidad con los estudios del área de Perfiles de la Cátedra de Psicología Experimental I y II, se llevó a cabo un análisis comparativo de Perfiles de Personalidad en estudiantes de psicología. La muestra fue intencional y autoseleccionada, quedó conformada por 153 estudiantes de Psicología. Se ha utilizado un diseño Descriptivo y Comparado. El instrumento utilizado fue el Inventario Multifásico de la Personalidad Minnesota-2 (MMPI-2). Los resultados reportan que existe un patrón de personalidad con similitudes muy acentuadas en los estudiantes de la carrera de psicología, independiente del curso al que pertenecen, y en comparación a los perfiles de años anteriores (n = 152, muestra 2001: n=168, muestra 2007: y n= 101 muestra 2008).
In continuity with the studies of the area of Profiles of the Professorship of Experimental Psychology I and II, a comparative analysis of Profiles of Personality in students of psychology was carried out. The sample was intentional and autoseleccionada, remained conformed by 153 (166) students of Psychology. A Descriptive design has been utilized and Compared. The instrument utilized was the Polyphase Inventory of the Personality Minnesota-2 (MMPI-2). The results report that a boss of personality with similarities exists very accentuated in the students of the career of psychology, independent of the course to which they belong, and in comparison to the profiles of previous years (n = 152 sample 2001; n = 168, sample 2007 and n = 101 sample 2008).
ABSTRACT
Se plantea una investigación con un diseño cuasi-experimental intragrupo prepost evaluación, cuyo objetivo es demostrar que la modificación de la política de pago de comisiones, de estándar a escalar (VI), influye en el nivel de satisfacción (VD) de una muestra de 40 vendedores de una compañía telefónica, que será medida por el Cuestionario De Satisfacción Laboral S10/12 (Meliá y Peiró, 1998). Se aplicará un análisis estadístico descriptivo e inferencial, para comprobar la relación funcional entre la VI (modificación de la política de pago de comisiones, de estándar a escalar) y la VD (aumento del nivel de satisfacción de los vendedores), recurriendo a la prueba t de Student para una sola muestra, con un nivel de significación de 0,05.