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Serving low-income children from birth to age five and their families, Head Start is a primary venue for identification and intervention in the area of child mental health. However, recent research has demonstrated that the knowledge base regarding prevalence, developmental course, and predictive power of child mental health problems is lacking for young children in general and low-income, diverse populations in particular. Head Start's agency-level data is often discrepant from both national estimates and small, intensive studies of similar populations, perhaps for reasons related to availability of community services and professional staff, as well as concerns about stigmatization. Following on recent expert recommendations, new collaborative Federal initiatives are underway to increase our understanding of the types, trajectories, and treatments of mental health problems affecting the vulnerable children served by Head Start. The paper concludes with a call to action for the field in the area of young children's mental health.  相似文献   
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The role of incentive learning in instrumental performance following a shift in the degree of water deprivation was analyzed in three experiments. In Experiments 1A and IB, rats trained to perform an instrumental action reinforced with either sucrose or maltodextrin solutions when in a high-deprivation state were subsequently shifted to a low-deprivation state and tested in extinction. This within-state shift in water deprivation reduced instrumental performance only when the animals had been exposed to the reinforcer in the low-deprivation state prior to instrumental training. In Experiment 2, a concurrent training procedure was used to assess whether the change in the value of the reinforcer brought about by preexposurewas mediated by the contingency between the instrumental action and the reinforcer. Preexposure to the reinforcer under the low-deprivation state produced a selective reduction of the performance of the action upon which it was contingent during training when testing was conducted in extinction following a shift from the high- to the low-deprivation state. These experiments provide evidence that animals have to learn about the incentive value of a reinforcer in a particular motivational state through exposure to the reinforcer in that state.  相似文献   
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The election of Raúl Alfonsín in October of 1983 represented the return of democracy to Argentina after more than seven years of a military dictatorship that left the country in a terribly distressed state. Since the dictatorship had joined the boycott of the 1980 Moscow Olympics led by the USA, for Argentina, the 1984 Los Angeles Olympics meant both coming back to the Olympic fold and the first such festival under the new democratic government. This paper explores Argentina's trajectory towards, and construction of, its participation in the country's first post-dictatorship Olympics. In doing so, this paper reveals why participation in the 1984 Los Angeles Olympics was not a priority for the incoming administration and why such participation was not conceived as a potential emissary capable of reaffirming on the global Olympic stage the hard fought, yet still emerging, democracy of Argentina. In addition, it reveals not only the determination of the Alfonsín administration to make his sport policy work but also its aspirations, complexity and ambiguities.  相似文献   
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The combined effects of pH and temperature on red pigment production and fungal morphology were evaluated in a submerged culture of Penicillium purpurogenum GH2, using Czapek-Dox media with d-xylose as a carbon source. An experimental design with a factorial fix was used: three pH values (5, 7, and 9) and two temperature levels (24 and 34 °C) were evaluated. The highest production of red pigment (2.46 g/L) was reached with a pH value of 5 and a temperature of 24 °C. Biomass and red pigment production were not directly associated. This study demonstrates that P. purpurogenum GH2 produces a pigment of potential interest to the food industry. It also shows the feasibility of producing and obtaining natural water-soluble pigments for potential use in food industries. A strong combined effect (p<0.05) of pH and temperature was associated with maximal red pigment production (2.46 g/L).  相似文献   
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