Resources,models, and theory in the improvement of research in science education     

Ralph W. Tyler 《科学教学研究杂志》1967,5(1):43-51

Research in science education is an interdisciplinary effort, fully meriting the allocation of university resources and the serious effort of able scholars.  相似文献   

The ADHD spectrum and everyday life: experience sampling of adolescent moods, activities, smoking, and drinking     

Whalen CK  Jamner LD  Henker B  Delfino RJ  Lozano JM 《Child development》2002,73(1):209-227

Using an experience sampling methodology, the everyday lives of 153 adolescents with low, middle, or high levels of attention-deficit/hyperactivity disorder (ADHD) characteristics as assessed by either parent or teen were examined. Twice each hour, across two 4-day recording intervals, participants in a longitudinal study of stress and health risks logged their behaviors, moods, and social contexts. Those with high, in contrast to low, ADHD symptom levels recorded more negative and fewer positive moods, lower alertness, more entertaining activities relative to achievement-oriented pursuits, more time with friends and less time with family, and more tobacco and alcohol use. Fewer associations emerged with parent-defined than with teen-defined subgroups, although the differences in alertness, peer and family contexts, entertainment versus achievement activities, and substance use were consistent across sources. Even at subclinical levels, ADHD characteristics were associated with behavioral patterns and contexts that may promote peer deviancy training, unhealthy lifestyle behaviors, and vulnerability to nicotine dependence.  相似文献   

Overshadowing of explicitly unpaired conditioned inhibition is disrupted by preexposure to the overshadowed inhibitor     

Aaron P. Blaisdell  Hernán I. Savastano  Ralph R. Miller 《Learning & behavior》1999,27(3):346-357

In two conditioned lick-suppression experiments with rats, the interaction of preexposure to a target stimulus and subsequent overshadowing of conditioned inhibition treatment was examined. Blaisdell, Bristol, Gunther, and Miller (1998) have demonstrated that stimulus preexposure and overshadowing counteract each other in their effects on Pavlovian excitation, producing strong excitatory responding to the target stimulus. In the present experiments, a conditioned inhibition analogue of this effect was examined. Overshadowing of conditioned inhibition (i.e., attenuation of inhibitory control of behavior by the target stimulus) was demonstrated when a more salient stimulus was compounded with the target inhibitor during conditioned inhibition training. However, the overshadowing deficit was attenuated by preexposing the target stimulus prior to overshadowing treatment. To account for this phenomenon, we contrast the comparator hypothesis (Miller & Matzel, 1988) with contemporary models that focus on associative acquisition.  相似文献   

Dielectrophoresis of DNA: Quantification by impedance measurements     

Anja Henning  Frank. F. Bier  Ralph H?lzel 《Biomicrofluidics》2010,4(2)

Dielectrophoretic properties of DNA have been determined by measuring capacitance changes between planar microelectrodes. DNA sizes ranged from 100 bp to 48 kbp, DNA concentrations from below 0.1 to 70 μg∕ml. Dielectrophoretic spectra exhibited maximum response around 3 kHz and 3 MHz. The strongest response was found for very long DNA (above 10 kbp) and for short 100 bp fragments, which corresponds to the persistence length of DNA. The method allows for an uncomplicated, automatic acquisition of the dielectrophoretic properties of submicroscopical objects without the need for labeling protocols or optical accessibility.  相似文献   

Overshadowing and CS duration: counteraction and a reexamination of the role of within-compound associations in cue competition     

Heather T. Sissons  Gonzalo P. Urcelay  Ralph R. Miller 《Learning & behavior》2009,37(3):254-268

In the present experiments, we examined the role of within-compound associations in the interaction of the overshadowing procedure with conditioned stimulus (CS) duration, using a conditioned suppression procedure with rats. In Experiment 1, we found that, with elemental reinforced training, conditioned suppression to the target stimulus decreased as CS duration increased (i.e., the CS duration effect), whereas, with compound reinforced training (i.e., the overshadowing procedure), conditioned suppression to the target stimulus increased as CS duration increased. In subsequent experiments, we replicated these findings with sensory preconditioning and demonstrated that extinction of the overshadowing stimulus results in retrospective revaluation with short CSs and in mediated extinction with long CSs. These results highlight the role of the duration of the stimulus in behavioral control. Moreover, these results illuminate one cause (the CS duration) of whether retrospective revaluation or mediated extinction will be observed.  相似文献   

Spacing extinction trials alleviates renewal and spontaneous recovery     

Gonzalo P. Urcelay  Daniel S. Wheeler  Ralph R. Miller 《Learning & behavior》2009,37(1):60-73

Studies of extinction in classical conditioning situations can reveal techniques that maximize the effectiveness of exposure-based behavior therapies. In three experiments, we investigated the effect of varying the intertrial interval during an extinction treatment in a fear-conditioning preparation with rats as subjects. In Experiment 1, we found less fear at test (i.e., more effective extinction) when extinction trials were widely spaced, relative to intermediate or massed extinction trials. In Experiment 2, we used an ABA renewal procedure and observed that spaced trials attenuated renewal of conditioned fear relative to massed trials. In Experiment 3, we used a similar design, but instead of changing the physical context at the time of testing, we interposed a retention interval after the extinction treatment to produce a change in the temporal context. The results showed less spontaneous recovery of fear after spaced than after massed extinction trials. These results suggest that extinction is more enduring when the extinction trials are spaced rather than massed. Although the benefits of spacing trials are small when there is no contextual change from extinction to testing, a change in either physical or temporal context following massed extinction trials leads to a recovery from extinction, which is reduced when the trials are spaced.  相似文献   

Editorial     

Sue Ralph  Julie Marshall  Juliet Goldbart 《Journal of Research in Special Educational Needs》2009,9(2):64-65

  相似文献   

Editorial     

Sue Ralph 《Journal of Research in Special Educational Needs》2009,9(3):139-140

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试论图书馆员国际交流项目及其评估——以四川大学和亚利桑那州立大学图书馆员交流项目为例   总被引：1，自引：0，他引：1  

胡琳  刘倩  Ralph B. Gabbard 《图书情报工作》2015,59(4):63-69

[目的/意义] 针对图书馆员国际交流项目缺乏评估研究的现状,提出一种有借鉴意义的测量工具来评估其实际效果和价值。[方法/过程] 以四川大学和亚利桑那州立大学图书馆员交流项目为例,参考D. Bachner和U. Zeutschel对国际青年交流项目的测量和评估方法确定评估标准,引入李克特五分量表,结合要求详细阐述的开放式问题,形成一个定性和定量相结合的评估工具。[结果/结论] 通过评估,对馆员交流项目进行全面审视,确定其在个人、机构、制度层面的影响和效果,发现项目决策、实施过程中的亮点与不足,提出促进馆员国际交流项目进一步发展的建议。  相似文献   

Rare cell isolation and profiling on a hybrid magnetic/size-sorting chip     

Jaehoon Chung  David Issadore  Adeeti Ullal  Kyungheon Lee  Ralph Weissleder  Hakho Lee 《Biomicrofluidics》2013,7(5)

We present a hybrid magnetic/size-sorting (HMSS) chip for isolation and molecular analyses of circulating tumor cells (CTCs). The chip employs both negative and positive cell selection in order to provide high throughput, unbiased CTC enrichment. Specifically, the system utilizes a self-assembled magnet to generate high magnetic forces and a weir-style structure for cell sorting. The resulting device thus can perform multiple functions, including magnetic depletion, size-selective cell capture, and on-chip molecular staining. With such capacities, the HMSS device allowed one-step CTC isolation and single cell detection from whole blood, tested with spiked cancer cells. The system further facilitated the study of individual CTCs for heterogeneity in molecular marker expression.Circulating tumor cells (CTCs) have emerged as an important biomarker in clinical practice as well as in fundamental research.^{1, 2} CTCs, shed from primary tumors, have been shown to be an early harbinger of tumor expansion and metastasis³ and have been used to predict disease progression, response to treatment, relapse, and overall survival.^{4, 5, 6} Recent work has shown that CTCs display distinct proteomic and genetic profiles; for example, CTCs in pancreatic cancer, have increased RNA expression of Wnt, implicating this pathway in metastasis.⁷ Proteomic characterization of proliferative markers such as Ki-67, and hormonal markers such as androgen receptor in prostate cancer, also have been shown to be predictive of treatment outcome.^{8, 9}Despite such clinical potential of CTCs, their routine detection and characterization still remains a significant technical challenge.¹⁰ The task requires screening of a large number of cells (e.g., > 10⁷ cells in 10 ml blood) and enrichment of heterogeneous targets against a complex biological background. Two main methods of CTC isolation are typically used: positive and negative selection. In positive selection, CTCs are directly isolated from blood via size-based filtration^{11, 12, 13, 14, 15, 16, 17, 18, 19, 20} or antibody-based capture.^{1, 8, 21} Negative depletion reduces abundant blood cells, often by immunomagnetic separation, for downstream CTC enrichment.²² Both approaches have been used for high throughput CTC isolation from whole blood (SI Table 1).²³ Each method, however, has its own inherent limitations. Positive enrichment could be biased by its selection criteria (e.g., cell size and cell surface markers). Negative selection, albeit unbiased, often requires complex sample processing (e.g., multiple washing steps for CTC isolation) that could result in cell loss.We hypothesized that both positive and negative selection could be combined in a single platform to enable (1) highly efficient and unbiased CTC purification, and (2) in-situ molecular analyses of collected cells. As a proof-of-concept, we herein describe a hybrid magnetic/size-sorting (HMSS) system that integrates magnetic and size-based isolation into a compact microfluidic chip. The HMSS first uses a magnetic filter to deplete leukocytes through immunomagnetic capture. Samples then pass through a size-sorter region that traps individual cells at predefined locations. Since abundant leukocytes are removed by the magnetic filter, the size-sorter could have a low size cut-off (∼5 μm), which allows for the unbiased capture of even small cancer cells. Furthermore, molecular probes can be introduced to perform on-chip, multiplexed analyses at single-cell resolution. We evaluated the utility of the developed system by capturing and profiling tumor cells in whole blood. The HMSS offers the advantages of both negative and positive selection and thereby differs from the recently reported iChip system²⁴ which can operate only in either a negative or a positive selection mode.  相似文献