A vacuum tube amplifier for small direct voltages     

Joseph Razek 《Journal of The Franklin Institute》1935,219(2):137-155

A simple means for combining a small direct voltage with an alternating carrier is described. This consists of connecting the direct voltage in series with an alternating voltage of the same order of magnitude. The two are then passed through a copper oxide rectifier which suppresses one part of the cycle. The degree of suppression depends upon the magnitude of the direct voltage. The resulting fluctuating voltage can be amplified to any desired degree in a conventional amplifier.The theory for the simple case of pure resistance is worked out, with an example. The solution of the more general case with inductances is indicated.The practical circuit which has been used for the amplification of thermo-couple currents, and as a galvanometer power multiplier, is shown.  相似文献   

Analytical Interference,Who Should Assess Kits?     

Jude Joseph Fleming 《Indian journal of clinical biochemistry : IJCB》2015,30(3):245-246

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Microfluidic chemical processing with on-chip washing by deterministic lateral displacement arrays with separator walls     

Yu Chen  Joseph D'Silva  Robert H. Austin  James C. Sturm 《Biomicrofluidics》2015,9(5)

We describe a microfluidic device for on-chip chemical processing, such as staining, and subsequent washing of cells. The paper introduces “separator walls” to increase the on-chip incubation time and to improve the quality of washing. Cells of interest are concentrated into a treatment stream of chemical reagents at the first separator wall for extended on-chip incubation without causing excess contamination at the output due to diffusion of the unreacted treatment chemicals, and then are directed to the washing stream before final collections. The second separator wall further reduces the output contamination from diffusion to the washing stream. With this approach, we demonstrate on-chip leukocyte staining with Rhodamine 6G and washing. The results suggest that other conventional biological and analytical processes could be replaced by the proposed device.  相似文献   

Physical activity patterns of ethnic children from low socio-economic environments within the UK     

Emma Lisa Jane Eyre  Michael Joseph Duncan  Samantha Louise Birch  Valerie Cox  Matthew Blackett 《Journal of sports sciences》2015,33(3):232-242

Many children fail to meet physical activity (PA) guidelines for health benefits. PA behaviours are complex and depend on numerous interrelated factors. The study aims to develop current understanding of how children from low Socio-economic environments within the UK use their surrounding built environments for PA by using advanced technology. The environment was assessed in 96 school children (7–9 years) using global positioning system (GPS) monitoring (Garmin Forerunner, 305). In a subsample of 46 children, the environment and PA were assessed using an integrated GPS and heart rate monitor. The percentage of time spent indoor, outdoor, in green and non-green environments along with time spent in moderate-to-vigorous PA (MVPA) in indoor and outdoor environments were assessed. A 2-by-2 repeated measures analysis of covariance, controlling for body mass index, BF%, assessed the environmental differences. The findings show that 42% of children from deprived wards of Coventry fail to meet PA guidelines, of which 43% was accumulated during school. Children engaged in more MVPA outdoor than indoor environments (P < 0.01) and a greater amount of time was spent in non-green environments (P < 0.01). Increased time outdoors was negatively associated with BF%. In conclusion, outdoor environments are important for health-enhancing PA and reducing fatness in deprived and ethnic children.  相似文献   

The evolving reference desk: A case study     

Christopher Ross Bowron  Joseph E. Weber 《The Journal of Academic Librarianship》2019,45(5):102057

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Evidence-based digital literacy class for older,low-income African-American adults     

Hyunjin Seo  Joseph Erba  Darcey Altschwager  Mugur Geana 《Journal of Applied Communication Research》2019,47(2):130-152

Based on our community engagement project involving 47 older, low-income African-American adults from a senior community center, this study analyzes how an underserved population acquires knowledge and skills related to digital technologies. We discuss the conceptualization, implementation, and evaluation of a weekly, four-month long computer class for members of the senior community center. Our mixed-method research shows the importance of taking into account both the multidimensional nature of adult learning and the social and cultural contexts in which learning occurs when working with underserved adult populations. Findings from our formative and evaluative research offer insights into changes in the computer class participants’ attitudes toward and perspectives on key digital literacy issues including security and privacy online and online information verification. Scholarly and policy implications are discussed in the context of digital competency and adult learning for marginalized populations.  相似文献   

Assessing the role of curriculum coherence in student learning about energy     

David Fortus  LeeAnn M. Sutherland Adams  Joseph Krajcik  Brian Reiser 《科学教学研究杂志》2015,52(10):1408-1425

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Towards critical appraisal of infographics as scientific inscriptions          下载免费PDF全文

Joseph L. Polman  Engida H. Gebre 《科学教学研究杂志》2015,52(6):868-893

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Anxiety and the Use of Alcohol‐Related Protective Behavioral Strategies     

Lucy E. Napper  Joseph W. LaBrie  Justin F. Hummer 《Journal of College Counseling》2015,18(1):21-36

Protective behavioral strategies (PBS) are useful skills for reducing the negative consequences of alcohol. The moderating effects of anxiety on the relationship between 3 different types of PBS and negative consequences were examined among students accessing college counseling services. Results revealed a significant interaction between anxiety and strategies while drinking, suggesting that these simple strategies may be particularly beneficial among students who drink heavily and experience high levels of anxiety. Implications for counseling centers are discussed.  相似文献   

Infant vocalizing and phenotypic outcomes in autism: Evidence from the first 2 years     

Samantha Plate  Lisa Yankowitz  Leslie Resorla  Meghan R. Swanson  Shoba Sreenath Meera  Annette Estes  Natasha Marrus  Meredith Cola  Victoria Petrulla  Aubrey Faggen  Juhi Pandey  Sarah Paterson  John R. Pruett Jr.  Heather Hazlett  Stephen Dager  Tanya St. John  Kelly Botteron  Lonnie Zwaigenbaum  Joseph Piven  Robert T. Schultz  Julia Parish-Morris  IBIS Network 《Child development》2022,93(2):468-483

Infant vocalizations are early-emerging communicative markers shown to be atypical in autism spectrum disorder (ASD), but few longitudinal, prospective studies exist. In this study, 23,850 infant vocalizations from infants at low (LR)- and high (HR)-risk for ASD (HR-ASD = 23, female = 3; HR-Neg = 35, female = 13; LR = 32, female = 10; 80% White; collected from 2007 to 2017 near Philadelphia) were analyzed at 6, 12, and 24 months. At 12 months, HR-ASD infants produced fewer vocalizations than HR-Neg infants. From 6 to 24 months, HR-Neg infants demonstrated steeper vocalization growth compared to HR-ASD and LR infants. Finally, among HR infants, vocalizing at 12 months was associated with language, social phenotype, and diagnosis at age 2. Infant vocalizing is an objective behavioral marker that could facilitate earlier detection of ASD.  相似文献