This work was focused on the assessment of changes occurring in crop production and climate during the 20th century in Argentina. The study was carried out for nine sites located in the Pampas region that are representative of contrasting environments. We have considered the four main crops cultivated in this area (wheat, maize, sunflower and soybean). Historical climatic data and crop production related variables (yield, planted area, harvested area) were analyzed and, by means of crop simulation models, we quantified the impact of climate on crop yields. Changes occurring in climate during the three last decades of the 20th century were characterized by important increases in precipitation especially between October and March, decreases in maximum temperature and solar radiation in particular during spring and summer and increases in minimum temperature during almost all of the year. These changes contributed to increases in yields, especially in summer crops and in the semiarid zone, mostly due to increases in precipitation, although changes in temperature and radiation also affected crop yields but to a lesser extent. Comparing the period 1950Comparing the period -1970Comparing the period with 1971Comparing the period -1999 yields increases attributable to changes in climate were 38% in soybean, 18% in maize, 13% in wheat, and 12% in sunflower while mean observed yield increases were 110% for maize, 56% for wheat and 102% for sunflower.

No abstract

The staff of youth development programs perform a delicate balancing act between supporting youth agency and exercising necessary authority. To understand this balancing in daily practice, we interviewed 25 experienced (M = 14 years) leaders of arts, leadership, and technology programs for high-school-aged youth. We obtained accounts of when, how, and why they gave advice, set limits, and "supported youth when disagreeing." Qualitative analysis found surprising similarities across leaders. They used authority to give advice and set limits, but did so with reasoned restraint. Maximizing youth's opportunities to learn from experience was central in their decision making. They described employing authority in intentional ways aimed at helping youth's work succeed, strengthening youth's agency, and building skills for agency (e.g., critical thinking, "clarifying intent").

No abstract

No abstract