全光波长变换器及其在光网络中的应用

All optical network (AON) is a hot topic in recentstudies of optical fiber communications . Key tech-niques in AONinclude optical switching/routing,opti-cal cross connection ( OXC) , all optical wavelengthconversion (AOWC) ,all optical buffering,etc. Opti…     

“Things your history teacher won't teach you: Science edition”: Black women science teachers as anti-racist teachers

Marginalized communities cannot and do not have decontextualized experiences with how socioscientific issues, such as exposure to COVID-19 as frontline essential workers, high Black infant mortality rates, air pollution leading to respiratory problems, and other issues, affect their communities. As PreK-12 science teachers and teacher educators strive to dismantle oppressive practices in their classrooms and curriculum, it would be helpful to learn from Black women science teachers who have been engaging in anti-racist practices before the racial awakenings of Summer 2020. In this study, three different virtual focus groups, or Sista Circles, were conducted with 18 Black women secondary science teachers. Ranging from 1 to 22 years of experience, Black women teachers across the country and international participants in Canada and Qatar participated in the Sista Circles. From intersectional qualitative analysis and narrative inquiry, the findings of the study reveal that Black women science teachers enact anti-racist science teaching by bringing something new to the community; using NGSS standards within the context of the community; teaching at the intersection of history, culture, and science learning and teaching; and building critical consciousness in the science classroom. Furthermore, the findings of the study have implications for the use of anti-racist frameworks within the context of science education that were authentically the practices of the Black women in the study. This study offers insights into how the critical consciousness of Black women teachers can be represented in the science classroom even in times of nonsupport from peers and administration. The power and necessity of Black women teachers are paramount in science classrooms specifically because of the neutral, apolitical ways science teaching has been approached in the past. The narratives and stories shared here exemplify how Black women science teachers transform science teaching and learning by displaying various acts of Criticality.     

The effect of acceleration signal processing for head impact numeric simulations

Brain injury research in sport employs a variety of physical models equipped with accelerometers. These acceleration signals are commonly processed using filters. The purpose of this research was to determine the effect of applying filters with different cutoff frequencies to the acceleration signals used as input for finite element modeling of the brain. Signals were generated from reconstructions of concussion events from American football and ice hockey in the laboratory using a Hybrid III headform. The resulting acceleration signals were used as input for the University College Dublin Brain Trauma Model after being processed with filters. The results indicated that using a filter with a cutoff of 300 Hz or higher had little effect on the resulting strain measures. In some cases there was some effect of the filters on the peak linear (8–30g) and rotational measures (1000–4000 rad/s²), but little effect on the finite element strain result (approximately 2–6 %). The short duration and high magnitude accelerations, such as the puck impact, were most affected by the cutoff frequency of different filters.     

Sequences of reward magnitude and runway performance

Three groups of rats underwent 24 days of training and 12 days of extinction (three trials per day) in a runway under conditions of increasing (I), decreasing (D), and random (R) sequences of reward magnitudes (0, 45, and 500 mg). The I Ss ran faster over the daily trials, the D Ss slowed down, and the R Ss ran at approximately equal speeds on each trial. The patterned running observed in training persisted in extinction, with the R Ss running fastest and the I Ss next. The results were discussed in terms of Capaldi’s sequential theory and Amsel’s frustration theory.     

A treatment program for failure to thrive: A cost/effectiveness analysis

Failure to thrive (FTT) is a frequent cause for the admission of infants to the hospital. Such hospitalizations are often lengthy and expensive, and usually do not contribute to an understanding of the etiology of FTT. Generally, organic causes of FTT can be ruled out by a thorough history and physical examination. In this study two groups were examined: 17 infants who were admitted to foster medical placement homes (MPH), private homes with specially trained parents; and a comparison group of 18 infants who were treated in a more traditional way with diagnostic hospitalization. The groups were similar in all regards prior to admission. All infants were less than a year of age. Family disruption was a prominent feature in both groups, but socio-demographic analysis showed them to be similar in all areas studied. The comparison group gained an average of 276 grams in the hospital over 8.6 days. The MPH group gained 362 grams in the hospital over 8.7 days, with an additional 1270 grams in the medical placement home over 31.1 days. Five children were admitted to the medical placement home without hospitalization. After correcting for an expected weight gain of 15 grams per day (normal growth), the comparison group showed a catch-up growth of 16 gms/day, while the MPH group gained 29 gms/day in excess of expectation, almost twice the comparison group. A 100-gram weight gain cost +308 in the MPH program and +1,635 in the traditional approach. This five-fold difference was felt to be a significant deterrent to the continuing approach of admitting children to the hospital for for the workup of FTT.(ABSTRACT TRUNCATED AT 250 WORDS)     

A Little Fire in BurgerLand

相似文献