Management of organic matter in the tropics: translating theory into practice

Inputs of organic materials play a central role in the productivity of many tropical farming systems by providing nutrients through decomposition and substrate for synthesis of soil organic matter (SOM). The organic inputs in many tropical farming systems such as crop residues, manures, and natural fallows are currently of low quality and insufficient quantity to maintain soil fertility hence there is need to find alternative or supplementary sources of nutrients. Knowledge gained over the past decade on the role of organic resource quality in influencing soil nutrient availability patterns (Synchrony Principle) and SOM maintenance (SOM Principle) provides a strong scientific basis on which to develop management tools. This scientific information must be linked with farmer knowledge and circumstances to provide a realistic approach to soil fertility and SOM management in the tropics. A decision tree has been developed for testing hypotheses about the resource quality parameters that affect nitrogen release patterns and rates. The decision tree is linked to an Organic Resource Database (ORD) with detailed information on the resource quality of agroforestry trees and leguminous cover crops providing a systematic means of selecting organic resources for soil fertility management. The decision tree has also been translated into a practical field guide for use with farmers in evaluating organic materials. The longer-term effects of organic inputs on SOM might also be addressed through the decision tree and database. It is generally believed that materials good for short-term soil fertility will not build or maintain SOM; if true then it is difficult to imagine practical means of maintaining SOM in the African context where short-term fertility issues will take precedence over longer-term maintenance of SOM. This revised version was published online in June 2006 with corrections to the Cover Date.     

BEH Amide柱：使碳水化合物的分析更简单、快速、高效

碳水化合物的色谱分析对很多行业的研究来说都是非常重要的工作。例如．食品中单糖与二糖的定性定量，由于复杂糖类．糖醇、人造甜味剂与盐皆可形成复杂基质．使分析变得困难；制药行业通常使用简单或复杂的糖类或糖衍生物基质作为起始药物．通过对药物配方中的这些化合物进行分析，可以为生产提供所需要的信息；     

Telepresence, soundscapes and technological expectation: putting the observer into the equation

In an experiment exploring the impact of sound on sensations of telepresence, 126 participants watched a video clip using either headphones or speakers. The results illustrate that sound is an important factor in stimulating telepresence responses in audiences. Interactions between soundscape and screen size were also revealed. A traverse interaction between aural/visual congruency and soundscapes was evident. A second data set of 102 participants was collected to illuminate the effect of technological expectation that emerged in the first study. Expectations had been mentioned in other studies, and the data support the notion that people have an expectation of the technological quality of a presentation. The results suggest that examining expectations could assist in future conceptualizations of telepresence.     

Texture mapping and distortion in digital graphics

Texture mapping is a method commonly used to increase the visual complexity of computer generated images while maintaining simplicity in the underlying geometric models. Texture maps are generally defined in two dimensional space; thus, a primary problem when applying textures to objects is determining a mapping transformation from the three dimensional space of the object to the two dimensional space of the map. A method for mapping complex polygonal geometries is presented. The algorithmunfolds the object polygon by polygon and projects the texture map onto the resulting two dimensional geometry. Enhancements to the basic unfolding algorithm either (1) control the location of map distorition introduced at areas of severe curvature or (2) average distortions over a larger area.     

"Controlling teaching strategies: Undermining children's self-determination and performance": Correction to Flink et al.

Reports an error in "Controlling teaching strategies: Undermining children's self-determination and performance" by Cheryl Flink, Ann K. Boggiano and Marty Barrett (Journal of Personality and Social Psychology, 1990[Nov], Vol 59[5], 916-924). In the article, Figure 1 on page 922 is labeled incorrectly. The labels in both the left and right panels of the figure should be reversed so that No Pressure Condition is the label for the broken lines and Pressure Condition is the label for the solid lines. The following abstract of the original article appeared in record 1991-13808-001.) Examined the hypothesis that students would show performance impairment when they were exposed to teachers who were pressured to maximize student performance level and who used controlling strategies. For this purpose, 4th-grade teachers and their students participated in a field experiment in which teachers either were pressured to maximize student performance or were told simply to help their students learn. In addition, the teaching sessions were videotaped to assess teachers' use of controlling strategies, as rated by blind coders. Following the teaching sessions, student performance on tasks initially taught by teachers as well as on a generalization task was assessed by blind experimenters. As predicted, the data indicated that students evidenced performance impairment during the subsequent testing session only when they were exposed to pressured teachers using controlling strategies. Results are discussed within the context of self-determination theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of encoding task on age-related differences in the functional neuroanatomy of face memory.

Age-related differences in brain activity mediating face recognition were examined using positron emission tomography. Participants encoded faces using a pleasant-unpleasant judgement, a right-left orientation task, and intentional learning. Scans also were obtained during recognition. Both young and old groups showed significant effects of encoding task on recognition accuracy, but older adults showed reduced accuracy overall. Increased brain activity in older adults was similar to that seen in young adults during conditions associated with deeper processing, but was reduced during the shallow encoding and recognition conditions. Differential correlations of brain activity and behavior were found that suggest older adults use unique neural systems to facilitate face memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relationship of racial stressors to blood pressure responses and anger expression in Black college students.

27 Black college students viewed 3 excerpts showing racist situations involving Blacks; anger-provoking, nonracist situations; and neutral situations. After each scene, blood pressure (BP) was taken; a mood checklist, the Framingham Anger Scale (S. Haynes et al; see PA, Vol 68:10702), and the Anger Expression Scale of C. Spielberger et al (1985) were administered. Analyses revealed that BP significantly increased during the presentation of racist stimuli but not of anger-provoking or neutral stimuli. Self-reports of state anger, as measured by the mood checklist, were significant for both the anger-provoking and racist stimuli. BP scores were significantly correlated to the 2 trait anger measures. Exposure to racist stimuli was associated with BP increases among Blacks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences in prevalence of tobacco use among Indian urban youth: the role of socioeconomic status

This study examined whether the distribution of tobacco use and related psychosocial risk factors among youth in urban India vary by socioeconomic status (SES). Data were derived from a cross-sectional survey of students enrolled in the 6th and 8th grades in 32 schools in Delhi and Chennai (N = 11,642). The survey was conducted in 2004, before the implementation of a program designed to prevent and reduce tobacco use (MYTRI). Mixed-effect regression models were used (a) to determine the prevalence of tobacco use among private (higher SES) and government (lower SES) school students, (b) to investigate whether certain psychosocial factors were associated with increased tobacco use, and (c) to determine how these factors varied by school type. Ever-use of multiple forms of tobacco (e.g., gutkha, bidis, and cigarettes) was more prevalent among government school students than private school students. After adjusting for city, gender, grade, and age, we found the prevalence rate for ever-use of any tobacco product to be 18.9% for government school students, compared with 12.2% for private school students (p<.01). Students in government schools scored lower than private school students on most psychosocial risk factors for tobacco use studied here, indicating higher risk. Government school students scored the lowest for refusal skills, self-efficacy, and reasons not to use tobacco. Social susceptibility to chewing tobacco and social susceptibility to smoking were strong correlates of current tobacco use among government school students. Exposure to tobacco advertising was also a strong correlate of current tobacco use for government school students but not private school students. In two large cities of India, students attending government schools are using many forms of tobacco at higher rates than private school students. The psychosocial risk profile of government school students suggests they are more vulnerable to initiation and use and to outside influences that encourage use.     

Mn+Sb2O3 Thermite/Intermetallic Delay Compositions

The binary Mn+Sb₂O₃ pyrotechnic composition was investigated for mining detonator time delay applications. EKVI thermodynamic modelling predicted two maxima in the adiabatic reaction temperature. The local maximum, at a manganese fuel content of ca. 36 wt‐%, corresponds to a pure thermite‐type redox reaction: 3 Mn+Sb₂O₃→3 MnO+2Sb. The overall maximum in the adiabatic reaction temperature (ca. 1640 K), at the fuel‐rich composition of 49 wt‐% Mn, is consistent with the reaction 5 Mn+Sb₂O₃→3 MnO+2 MnSb, i.e. a combination of the standard thermite with an additional exothermic intermetallic reaction. XRD analysis of combustion residues confirmed the formation of MnSb and Mn₂Sb for fuel‐rich compositions. Burn rates were measured using delay elements assembled into commercial detonators. The d₅₀ particle sizes were 23.4 and 0.92 μm for the Mn fuel and Sb₂O₃ oxidant powders, respectively. The delay elements comprised rolled lead tubes with a length of 44 mm and an outer diameter of 6.4 mm. The rolling action compacted the pyrotechnic compositions to 74 ± 2 % theoretical maximum density. The burning rate increased linearly from 4.2 to 9.4 mm s⁻¹ over the composition range 25–50 wt‐% Mn.