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- Resource Type:
- Article
- Creator:
- Nimijean, Richard
- Date Created:
- 2005-02-01
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- Resource Type:
- Article
- Creator:
- Ibrahim, Marc, Janz, Siegfried, Cheben, Pavel, Xu, Dan-Xia, Schmid, Jens H., Ma, Rubin, Aleali, Alireza, Lamontagne, Boris, Bock, Przemek J., Lapointe, Jean, Densmore, Adam, and Ye, Winnie N.
- Abstract:
- In this paper, athermal silicon waveguides using bridged subwavelength grating (BSWG) structures are proposed and investigated. The realization of temperature-independent BSWG waveguides for both polarizations is demonstrated numerically and experimentally. SU-8 polymer is used as the cladding material to compensate for the positive thermo-optic (TO) coefficient (dn/dT) of silicon. We investigate the dependence of the effective TO coefficient of BSWG waveguides on both the bridge width and grating duty cycle. The BSWG waveguides have a width of 490 nm, a height of 260 nm, and a grating pitch of 250 nm. Athermal behavior is achieved for both the transverse-magnetic (TM) and the transverse-electric (TE) polarized light for a variety of bridge width and duty cycle combinations. Furthermore, the BSWGs can be designed to be athermal for both TE and TM polarization simultaneously.
- Date Created:
- 2012-07-30
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- Resource Type:
- Article
- Creator:
- D'Angiulli, Amedeo, Lipina, Sebastian J., and Olesinska, Alice
- Abstract:
- The appearance of developmental cognitive neuroscience (DCN) in the socioeconomic status (SES) research arena is hugely transformative, but challenging. We review challenges rooted in the implicit and explicit assumptions informing this newborn field. We provide balanced theoretical alternatives on how hypothesized psychological processes map onto the brain (e.g., problem of localization) and how experimental phenomena at multiple levels of analysis (e.g., behavior, cognition and the brain) could be related. We therefore examine unclear issues regarding the existing perspectives on poverty and their relationships with low SES, the evidence of low-SES adaptive functioning, historical precedents of the “alternate pathways” (neuroplasticity) interpretation of learning disabilities related to low-SES and the notion of deficit, issues of “normativity” and validity in findings of neurocognitive differences between children from different SES, and finally alternative interpretations of the complex relationship between IQ and SES. Particularly, we examine the extent to which the available laboratory results may be interpreted as showing that cognitive performance in low-SES children reflects cognitive and behavioral deficits as a result of growing up in specific environmental or cultural contexts, and how the experimental findings should be interpreted for the design of different types of interventions—particularly those related to educational practices—or translated to the public—especially the media. Although a cautionary tone permeates many studies, still, a potential deficit attribution—i.e., low-SES is associated with cognitive and behavioral developmental deficits—seems almost an inevitable implicit issue with ethical implications. Finally, we sketch the agenda for an ecological DCN, suggesting recommendations to advance the field, specifically, to minimize equivocal divulgation and maximize ethically responsible translation.
- Date Created:
- 2015-08-21
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- Resource Type:
- Article
- Creator:
- Graham, Debra, Couchman, Ronald, and Hempstead, Janet
- Abstract:
- Undergraduate collaborative research is highlighted in many university initiatives; how-ever there is a lack of exemplars in disciplines that do not employ the scientific method. “Pop Music Reviews” was an attempt to forge a template for Women’s and Gender Stud-ies. This paper presents a description of the pilot project and provides qualitative assess-ments by the first- and second-year students, fourth-year teaching assistant (TA), refer-ence librarian, and professor. Together, the appraisals indicate that there are two different but equally necessary components for a successful collaborative research endeavour: the structural setting and the social and emotional environment. In both these components, there were weaknesses in the areas of planning and background training. Yet, the benefits as perceived through the experiences of the various participants were significant. Report-ed gains included increased understanding of research processes and applications, en-hanced critical thinking skills, expanded disciplinary knowledge, improved student moti-vation and confidence, greater interest in graduate studies, and the fostering of collegial interactions and mentoring.
- Date Created:
- 2012-09-09
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Vividness of visual imagery and incidental recall of verbal cues, when phenomenological availability
- Resource Type:
- Article
- Creator:
- Zakizadeh, Jila, Runge, Matthew, Faulkner, Andrew, D'Angiulli, Amedeo, Morcos, Selvana, and Chan, Aldrich
- Abstract:
- The relationship between vivid visual mental images and unexpected recall (incidental recall) was replicated, refined, and extended. In Experiment 1, participants were asked to generate mental images from imagery-evoking verbal cues (controlled on several verbal properties) and then, on a trial-by-trial basis, rate the vividness of their images; 30 min later, participants were surprised with a task requiring free recall of the cues. Higher vividness ratings predicted better incidental recall of the cues than individual differences (whose effect was modest). Distributional analysis of image latencies through ex-Gaussian modeling showed an inverse relation between vividness and latency. However, recall was unrelated to image latency. The follow-up Experiment 2 showed that the processes underlying trial-by-trial vividness ratings are unrelated to the Vividness of Visual Imagery Questionnaire (VVIQ), as further supported by a meta-analysis of a randomly selected sample of relevant literature. The present findings suggest that vividness may act as an index of availability of long-term sensory traces, playing a non-epiphenomenal role in facilitating the access of those memories.
- Date Created:
- 2013-01-02
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- Resource Type:
- Article
- Creator:
- Fitzsimmons, Lauren P., Harrison, Sarah J., Thomson, Ian R., and Bertram, Susan
- Abstract:
- Phenotypic plasticity can be adaptive when phenotypes are closely matched to changes in the environment. In crickets, rhythmic fluctuations in the biotic and abiotic environment regularly result in diel rhythms in density of sexually active individuals. Given that density strongly influences the intensity of sexual selection, we asked whether crickets exhibit plasticity in signaling behavior that aligns with these rhythmic fluctuations in the socio-sexual environment. We quantified the acoustic mate signaling behavior of wild-caught males of two cricket species, Gryllus veletis and G. pennsylvanicus. Crickets exhibited phenotypically plastic mate signaling behavior, with most males signaling more often and more attractively during the times of day when mating activity is highest in the wild. Most male G. pennsylvanicus chirped more often and louder, with shorter interpulse durations, pulse periods, chirp durations, and interchirp durations, and at slightly higher carrier frequencies during the time of the day that mating activity is highest in the wild. Similarly, most male G. veletis chirped more often, with more pulses per chirp, longer interpulse durations, pulse periods, and chirp durations, shorter interchirp durations, and at lower carrier frequencies during the time of peak mating activity in the wild. Among-male variation in signaling plasticity was high, with some males signaling in an apparently maladaptive manner. Body size explained some of the among-male variation in G. pennsylvanicus plasticity but not G. veletis plasticity. Overall, our findings suggest that crickets exhibit phenotypically plastic mate attraction signals that closely match the fluctuating socio-sexual context they experience.
- Date Created:
- 2013-07-22
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- Resource Type:
- Article
- Creator:
- Katti, Madhusudan and Bertram, Susan
- Abstract:
- Evolutionary biology and ecology have always been collaborative enterprises, benefitting enormously from active communication of ideas among traditional academic networks of peers. The Internet age, with its thriving online social networks, offers new tools that can help our current generation of biologists to collaborate, and communicate with the public, more effectively. Having a dynamic web presence, being part of an active blogging, Facebook, or Google+ community, and being a strategic tweeter can help your research, teaching, and service programs. Below we outline how to be a strategically savvy and active social media scientist, and discuss some of the pitfalls to avoid wasting time. We highlight some ecologists and evolutionary biologists who are active in social media to help you understand the many ways social media can help you in your academic life.
- Date Created:
- 2013-07-07
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- Resource Type:
- Article
- Creator:
- Holahan, Matthew, Cahill, Shaina, and Tuplin, Erin
- Abstract:
- Seasonal fluctuations in food availability show a tight association with seasonal variations in body weight and food intake. Seasonal variations in food intake, energy storage and expenditure appear to be a widespread phenomenon suggesting they may have evolved in anticipation for changing environmental demands. These cycles appear to be driven by changes in external daylength acting on neuroendocrine pathways. A number of neuroendocrine pathways, two of which are the endocrine mechanisms underlying feeding and stress, appear to show seasonal changes in both their circulating levels and reactivity. As such, variation in the level or reactivity to these hormones may be crucial factors in the control of seasonal variations in food-seeking behaviours. The present review examines the relationship between feeding behavior and seasonal changes in circulating hormones. We hypothesize that seasonal changes in circulating levels of glucocorticoids and the feeding-related hormones ghrelin and leptin contribute to seasonal fluctuations in feeding-related behaviors. This review will focus on the seasonal circulating levels of these hormones as well as sensitivity to these hormones in the modulation of food-seeking behaviors.
- Date Created:
- 2013-07-23
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- Resource Type:
- Article
- Creator:
- D'Angiulli, Amedeo, Aragón-Flores, Mariana, Mukherjee, Partha S., Cross, Janet V., Gómez-Garza, Gilberto, Zhu, Hongtu, Chao, Chih-kai, Mora-Tiscareño, Antonieta, Franco-Lira, Maricela, Engle, Randall, Jewells, Valerie, Solorio, Edelmira, Weili, Lin, Medina-Cortina, Humberto, Torres-Jardón, Ricardo, Calderón-Garcidueñas, Lilian, and Ferreira-Azevedo, Lara
- Abstract:
- Air pollution exposures are linked to systemic inflammation, cardiovascular and respiratory morbidity and mortality, neuroinflammation and neuropathology in young urbanites. In particular, most Mexico City Metropolitan Area (MCMA) children exhibit subtle cognitive deficits, and neuropathology studies show 40% of them exhibiting frontal tau hyperphosphorylation and 51% amyloid-β diffuse plaques (compared to 0% in low pollution control children). We assessed whether a short cocoa intervention can be effective in decreasing plasma endothelin 1 (ET-1) and/or inflammatory mediators in MCMA children. Thirty gram of dark cocoa with 680 mg of total flavonols were given daily for 10.11 ± 3.4 days (range 9–24 days) to 18 children (10.55 years, SD = 1.45; 11F/7M). Key metabolite ratios in frontal white matter and in hippocampus pre and during cocoa intervention were quantified by magnetic resonance spectroscopy. ET-1 significantly decreased after cocoa treatment (p = 0.0002). Fifteen children (83%) showed a marginally significant individual improvement in one or both of the applied simple short memory tasks. Endothelial dysfunction is a key feature of exposure to particulate matter (PM) and decreased endothelin-1 bioavailability is likely useful for brain function in the context of air pollution. Our findings suggest that cocoa interventions may be critical for early implementation of neuroprotection of highly exposed urban children. Multi-domain nutraceutical interventions could limit the risk for endothelial dysfunction, cerebral hypoperfusion, neuroinflammation, cognitive deficits, structural volumetric detrimental brain effects, and the early development of the neuropathological hallmarks of Alzheimer's and Parkinson's diseases.
- Date Created:
- 2013-08-02
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- Resource Type:
- Article
- Creator:
- LeFevre, Jo-Anne, Kamawar, Deepthi, Jimenez Lira, Carolina, Sowinski, Carla, Cankaya, Ozlem, and Skwarchuk, Sheri-Lynn
- Abstract:
- Individuals who do well in mathematics and science also often have good spatial skills. However, the predictive direction of links between spatial abilities and mathematical learning has not been firmly established, especially for young children. In the present research, we addressed this issue using a sample from a longitudinal data set that spanned 4 years and which includes measures of mathematical performance and various cognitive skills, including spatial ability. Children were tested once in each of 4 years (Time 1, 2, 3, and 4). At Time 3 and 4, 101 children (in Grades 2, 3, or 4 at Time 3) completed mathematical measures including (a) a number line task (0–1000), (b) arithmetic, and (c) number system knowledge. Measures of spatial ability were collected at Time 1, 2, or 3. As expected, spatial ability was correlated with all of the mathematical measures at Time 3 and 4, and predicted growth in number line performance from Time 3 to Time 4. However, spatial ability did not predict growth in either arithmetic or in number system knowledge. Path analyses were used to test whether number line performance at Time 3 was predictive of arithmetic and number system knowledge at Time 4 or whether the reverse patterns were dominant. Contrary to the prediction that the number line is an important causal construct that facilitates learning arithmetic, no evidence was found that number line performance predicted growth in calculation more than calculation predicted number line growth. However, number system knowledge at Time 3 was predictive of number line performance at Time 4, independently of spatial ability. These results provide useful information about which aspects of growth in mathematical performance are (and are not) related to spatial ability and clarify the relations between number line performance and measures of arithmetic and number system knowledge.
- Date Created:
- 2013-08-29