632 resultados para Urponen, Maija


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The aim of the study was to investigate the structure of affective and cognitive engagement using the Student Engagement Instrument (SEI; Appleton, Christenson, Kim, & Reschly, 2006) and to examine the associations to behavioral engagement, as well as student-reported self-esteem, burnout, and academic achievement among Finnish junior high school students. The analyses were carried out in the main sample of 2,485 students, as well as in an independent sample of 821 students. The results showed that the original five-factor structure of the SEI construed along three affective and two cognitive engagement factors fit the current data relatively well. Affective and cognitive student engagement correlated positively with an independent measure of behavioral engagement. Furthermore, affective and cognitive engagement were positively associated with student-reported self-esteem and academic achievement, and negatively with school burnout. The findings provided corroborating evidence for the psychometric properties and utilization of the SEI instrument for assessing the engagement of junior high school students. (DIPF/Orig.)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In May, June and July 1996, samples wcre collected along one transect greatly influenced by river discharge (eastern side of the gulf), along one transect slightly influence by river discharge (western side), at one station Iocated in the mouth of the main river (River Daugava), at one station located in the center of the Gulf and at several nearshore locations of the western side. Ratios of rnolecular concentrations of in situ dissolved ioorganic nitrogen, phosphorus and silicon, as weIl as enrichment bioassays were llsed to dctcrrnine which nutrient (s) lirnited the potential biomass of phytoplankton. Both comparison of (NO.d-N02+NJ.L): P04 (DIN: DIP) values with Redfic1d's ratio and bioassay inspection led to the sarne conclusions. Phosphorus was clearly the nutrient most limiting for the potcntial biornass of test species in nitrogen- rich waters, which occurred in mid spring, in the upper layer of the southern-eastern part of the Gulf which is greatly influenced by river discharge. In late spring, with the decrease of the total DIN reserve, nitrogen and phosphorus showed an equallimiting role. In deeper layers of this area and out of the river plume (western side and central part of the gulf), nitrogen was the limiting nutrient. In summer, whcn river discharge was the lowest, a11 DIN concentrations but one ranged between 1.6 and 2.6 µM, and the whole area was nitrogen-limited for both the cyanobacterial and the algal test strains. In 74% of the samples for which nitrogen was the limiting nutrient, phosphorus was recorded to be the second potentially limiting nutrient. In contrast, silicon never appeared as limiting the growth potential of either Microcystis aeruginosa or Phaeodactylum tricornutum; phosphorus was the limiting nutrient when DIN: Si03 values were >1 (in May), but DIN: Si03 was <1 when nitrogen was limiting (June and July). The authors conclude that the recently reported decrease of silicon loading in coastal waters and its subsequent enhanced importance in pushing the outcome of species competition towards harmful species may not yet be the most important factor for the Gulf of Riga. Iron appeared for 12% of the tests in the list of nutrients limiting the potential biomass. Tentative results also indicated that a significant fraction of the nitrogen (~,4 µg-atom N 1(-1) taken up by Microcystis aeruginosa may have been in the form of dissolved organic nitrogen (DON). It is thus also suggested tentatively that more attention be paid to these nitrients during further research in the Gulf of Riga.