水体中重金属离子的形态及其对生物富集影响

详细介绍了水体中重金属离子形态的划分方法 ,阐述了重金属形态与生物富集的关系及其影响因素 ,指出该研究领域目前亟待解决的问题     

Brightness assimilation in bullseye displays

In simultaneous brightness contrast displays, a gray target square G(B) bordered by black appears brighter than an identical gray target square G(W) bordered by white. Here we demonstrate that this effect can be reversed if G(B) is surrounded by bands that alternate outward from black to white, while G(W) is surrounded by bands that alternate outward from white to black. With these simple "bullseye" displays assimilation generally occurs--G(B) appears darker than G(W). Experiments 1 and 2 used a 2AFC design with a 2.2 s display duration. The results of these experiments indicate that (i) substantial assimilation occurs for target Weber contrasts (relative to the gray background) of -0.25, 0, and 0.25, but assimilation was maximal when target contrast was -0.25 and decreased as target contrast increased, (ii) assimilation effects were the same whether the width of the four surround bands was 20% of the target or 40% of the target, and (iii) assimilation occurs with as few as 2 surround-bands and the magnitude of the effect increases slightly as the number of bands increase. When experiment 1 was re-run using the method of matching (experiment 3), however, the results changed dramatically: (moderate) assimilation effects were found only when target contrast was -0.25; when target contrast was 0.25, there was a brightness contrast effect; when target contrast was 0, there was no illusion. Assimilation effects in bullseye displays are not predicted by the CSF model described in DeValois and DeValois [Spatial Vision, Oxford University Press, New York, 1988], the anchoring model of Gilchrist et al. [Psychological Review, 106(4) (1999) 795], or Blakeslee and McCourt's [Vision Research 39 (1999) 4361] ODOG model. We propose that this assimilation effect is the result of a contrast inhibition mechanism similar to that proposed by Chubb et al. [Proceedings for the National Academy of Science, vol. 86, 1989, p. 9631] to underlie contrast effects.     

Context effects in haptic perception of roughness

The influence of temporal and spatial context during haptic roughness perception was investigated in two experiments. Subjects examined embossed dot patterns of varying average dot distance. A two-alternative forced-choice procedure was used to measure discrimination thresholds and biases. In Experiment 1, subjects had to discriminate between two stimuli that were presented simultaneously to adjacent fingers, after adaptation of one of these fingers. The results showed that adaptation to a rough surface decreased the perceived roughness of a surface subsequently scanned with the adapted finger, whereas adaptation to a smooth surface increased the perceived roughness (i.e. contrast after effect). In Experiment 2, subjects discriminated between subsequent test stimuli, while the adjacent finger was stimulated simultaneously. The results showed that perceived roughness of the test stimulus shifted towards the roughness of the adjacent stimulus (i.e. assimilation effect). These contextual effects are explained by structures of cortical receptive fields. Analogies with comparable effects in the visual system are discussed.     

Immigrant generation, socioeconomic status, and economic development of countries of origin: a longitudinal study of body mass index among children

Prior research has yielded mixed evidence of a relationship between immigrant generational status or acculturation and overweight or obesity among children of immigrants. This study examined socioeconomic status (SES) and economic development of the sending country as additional factors influencing children body mass index (BMI) and as moderating the relationship between parental generational status and BMI. Using data from the kindergarten cohort of the Early Childhood Longitudinal Survey (N=16,664 children) carried out in the USA, the research estimated growth curve models and tested the significance of interaction terms between generational status (i.e., children of the 1.0 generation, who arrived at age 12 or older; children of the 1.5 generation, who arrived between the ages of birth and 11; and children of natives), SES, and the country of origin's gross domestic product per capita. Results indicate that the children of the 1.0 generation from higher-income countries tended to gain more weight than children from lower-income countries. The relationship between family SES and weight gain was positive among the first-generation children and stronger among those from lower-income countries than from higher-income countries. Weight gain was positively associated with generation only among lower SES children from low-income countries. It was negatively associated with generation for higher SES children from low-income countries. The results are consistent with a conceptual model of BMI assimilation that links global nutrition patterns to the levels and socioeconomic variations in BMI among the 1.0-generation and their children, and conceptualizes assimilation as occurring within socioeconomic strata. This approach leads to the expectation that overweight is likely to be positively associated with generation among those from low-income countries (as measured by GDP/capita) with low SES but negatively associated among those from low-income countries with high SES.     

The watercolor effect: quantitative evidence for luminance-dependent mechanisms of long-range color assimilation

When a dark chromatic contour delineating a figure is flanked on the inside by a brighter chromatic contour, the brighter color will spread into the entire enclosed area. This is known as the watercolor effect (WCE). Here we quantified the effect of color spreading using both color-matching and hue-cancellation tasks. Over a wide range of stimulus chromaticities, there was a reliable shift in color appearance that closely followed the direction of the inducing contour. When the contours were equated in luminance, the WCE was still present, but weak. The magnitude of the color spreading increased with increases in luminance contrast between the two contours. Additionally, as the luminance contrast between the contours increased, the chromaticity of the induced color more closely resembled that of the inside contour. The results support the hypothesis that the WCE is mediated by luminance-dependent mechanisms of long-range color assimilation.     

Assimilation approach to measuring organizational change from pre- to post-intervention

AIM: To present a conceptual and measurement strategy that allows to objectively, sensitively evaluate intervention progress based on data of participants’ perceptions of presenting problems.METHODS: We used as an example an organization development intervention at a United States Veterans Affairs medical center. Within a year, the intervention addressed the hospital’s initially serious problems and multiple stakeholders (employees, management, union representatives) reported satisfaction with progress made. Traditional quantitative outcome measures, however, failed to capture the strong positive impact consistently reported by several types of stakeholders in qualitative interviews. To address the paradox, full interview data describing the medical center pre- and post- intervention were examined applying a validated theoretical framework from another discipline: Psychotherapy research. The Assimilation model is a clinical-developmental theory that describes empirically grounded change levels in problematic experiences, e.g., problems reported by participants. The model, measure Assimilation of Problematic Experiences Scale (APES), and rating procedure have been previously applied across various populations and problem types, mainly in clinical but also in non-clinical settings. We applied the APES to the transcribed qualitative data of intervention participants’ interviews, using the method closely replicating prior assimilation research (the process whereby trained clinicians familiar with the Assimilation model work with full, transcribed interview data to assign the APES ratings). The APES ratings summarized levels of progress which was defined as participants’ assimilation level of problematic experiences, and compared from pre- to post-intervention.RESULTS: The results were consistent with participants’ own reported perceptions of the intervention impact. Increase in APES levels from pre- to post-intervention suggested improvement, missed in the previous quantitative measures (the Maslach Burnout Inventory and the Work Environment Scale). The progress specifically consisted of participants’ moving from the APES stages where the problematic experience was avoided, to the APES stages where awareness and attention to the problems were steadily sustained, although the problems were not yet fully processed or resolved. These results explain why the conventional outcome measures failed to reflect the intervention progress; they narrowly defined progress as resolution of the presenting problems and alleviation of symptomatic distress. In the Assimilation model, this definition only applies to a sub-segment of the change continuum, specifically the latest APES stages. The model defines progress as change in psychological processes used in response to the problem, i.e., a growing ability to deal with problematic issues non-defensively, manifested differently depending on APES stages. At early stages, progress is an increased ability to face the problem rather than turning away. At later APES stages, progress involves naming, understanding and successfully addressing the problem. The assimilation approach provides a broader developmental context compared to exclusively symptom, problem-, or behavior- focused approaches that typically inform outcome measurement in interpersonally based interventions. In our data, this made the difference between reflecting (APES) vs missing (Maslach Burnout Inventory, Work Environment Scale) the pre-post change that was strongly perceived by the intervention recipients.CONCLUSION: The results illustrated a working solution to the challenge of objectively evaluating progress in subjectively experienced problems. This approach informs measuring change in psychologically based interventions.     

MIGRATION AND SUBSTANCE USE: EVIDENCE FROM THE U.S. NATIONAL HEALTH INTERVIEW SURVEY*

Representative data from the U.S. National Health Interview Survey are used to investigate the substance use patterns of immigrants and compare them to those of the native born populations. The information examined is from the 1991 supplementary Drug and Alcohol Use Data File, which examined the self-reported substance use behaviors of approximately 21,000 adults aged 18–44. Findings indicate that immigrants to the U.S. in the late twentieth century are less likely to use alcohol and other drugs than are native born citizens. Additional findings suggest assimilation processes by which exposure to mainstream American society leads to patterns of alcohol and illicit drug use among long term immigrants that approximates that of the native born population. The patterns of substance use observed among immigrants, however, are not consistent with acculturative stress mechanisms. These findings provide an important and representative profile of the substance use patterns of one of the largest international migration streams of the past one hundred years.     

Immigrant generation and physical activity among Mexican,Chinese & Filipino adults in the U.S.

Migrant studies of physical activity (PA) can provide insight into the prevention of chronic disease. It is unclear, however, whether PA increases or decreases the longer migrants live in their host country. In the US, studies on immigrants’ length of residence in the US and PA are inconclusive and many studies do not adequately consider the role of socioeconomic status (SES). Using California data, we examine relationships between immigrant generation and physical activity (PA) among Mexican, Chinese and Filipino adults, who represent the three largest immigrant groups in the US, and the extent to which the relationships are confounded by SES. Data from the 2000 US Census was linked with data on adults 18 years and older from the 2005 California Health Interview Survey. PA was measured in three different domains: leisure time (LTPA), non-leisure time (NLTPA) and any PA. Logistic regression was used to examine whether a wide range of SES factors, measured at the respondent and neighborhood levels, influenced the relationship between immigrant generation and PA in all domains and in different ethnic origin groups.     

五行学说的发生认识论解释

文章从皮亚杰发生认识论的视角出发,对五行学说概念系统的演进过程进行研究,试图厘清五行学说在其漫长而辉煌的发展历程中,经历了哪些主要的发展阶段,这些阶段分别都有什么特征,从前一个主要阶段到下一个主要阶段的发展过程中,这些相邻阶段之间又有什么必然的联系。通过研究和分析,我们认为皮亚杰发生认识论中的"4个不同发展阶段理论"能够对五行学说发生发展进程的演变进行解释。