Modular Assembly of Metamaterials Using Light Gradients.

This is a report on a pilot study that tests the feasibility of assembling photonic metamaterials (PMs) using light gradient forces. Following a strategy that works like modular construction, light gradient forces, produced by a tightly focused, one-dimensional standing wave optical trap (SWOT), time-multiplexed across a two-dimensional lattice were used to assemble voxels consisting of prefabricated, monodispersed nanoparticles (NPs) with radii ranging from 30 to 500 nm into three-dimensional structures on a hydrogel scaffold. Hundreds of NPs can be manipulated concurrently into a complex heterogeneous voxel this way, and then the process can be repeated by stitching together voxels to form a metamaterial of any size, shape, and constituency although imperfectly. Imperfections introduce random phase-shifts and amplitude variations that can have an adverse effect on the band structure. Regardless, PMs were created this way using two different dielectric NPs, polystyrene and rutile, and then the near-infrared performance for each was analyzed with angle-, wavelength-, and polarization-dependent reflection spectroscopy. The cross-polarized spectra showed evidence of a resonance peak. Interestingly, whereas the line-shape from the polypropylene array was symmetric, the rutile array was not, which may be indicative of Fano resonance. So, even with the structural defects, reflection spectroscopy revealed a resonance. This article is protected by copyright. All rights reserved.

Negative allometry of leaf xylem conduit diameter and double-wall thickness: implications for implosion safety.

Xylem conduits have lignified walls to resist crushing pressures. The thicker the double-wall (T) relative to its diameter (D), the greater the implosion safety. Having safer conduits may incur higher costs and reduced flow, while having less resistant xylem may lead to catastrophic collapse under drought. Although recent studies have shown that conduit implosion commonly occurs in leaves, little is known about how leaf xylem scales T vs D to trade off safety, flow efficiency, mechanical support, and cost. We measured T and D in > 7000 conduits of 122 species to investigate how T vs D scaling varies across clades, habitats, growth forms, leaf, and vein sizes. As conduits become wider, their double-cell walls become proportionally thinner, resulting in a negative allometry between T and D. That is, narrower conduits, which are usually subjected to more negative pressures, are proportionally safer than wider ones. Higher implosion safety (i.e. higher T/D ratios) was found in asterids, arid habitats, shrubs, small leaves, and minor veins. Despite the strong allometry, implosion safety does not clearly trade off with other measured leaf functions, suggesting that implosion safety at whole-leaf level cannot be easily predicted solely by individual conduits' anatomy.

Dweck's Social-Cognitive Model of Achievement Motivation in Science.

Dweck's social-cognitive model has long been used as a basis for achievement motivation research. However, few studies have examined the comprehensive model with interactions between perceived ability and achievement goals, and even fewer studies have focused on this model in a science academic context. With a sample of undergraduates (n = 1,036), the relations among mindsets, science academic self-efficacy, achievement goals, and achievement-related outcomes in science were examined. Fixed mindset related to performance goals. Growth mindset related to mastery goals and the number of courses completed. There was a significant indirect effect of growth mindset on interest value via mastery goals. Contrary to Dweck's model, the relation of performance goals to outcomes did not vary as a function of science academic self-efficacy. The findings provide empirical evidence for a more nuanced understanding of Dweck's model. They provide practical insights for how to support undergraduate students who are pursuing science-related career.

Patterns, predictors, and outcomes of situated expectancy-value profiles in an introductory chemistry course.

Using latent profile analysis, we identified profiles of expectancy beliefs, perceived values, and perceived costs among 1433 first- and second-year undergraduates in an introductory chemistry course for STEMM majors. We also investigated demographic differences in profile membership and the relation of profiles to chemistry final exam achievement, science/STEMM credits completed, and graduating with a science/STEMM major. Four motivational profiles were identified: Moderately Confident and Costly (profile 1), Mixed Values-Costs/Moderate-High Confidence (profile 2), High Confidence and Values/Moderate-Low Costs (profile 3), and High All (profile 4). Underrepresented students in STEMM were more likely to be in profile 2 relative to profile 3. First-generation college students were more likely to be in profile 4 than profile 3. Finally, students likely to be in profile 3 had higher final exam grades than the other profiles and were more likely to graduate with a science major compared to profile 1. There were no differences in graduating science major between profile 3 and the other two profiles. Thus, profile 3 was most adaptive for both proximal (final exam) and distal (graduating with a science major) outcomes. Results suggest that supporting motivation early in college is important for persistence and ultimately the talent development of undergraduate STEMM students.

Recurrent High-Grade Squamous Intraepithelial Lesion After Loop Excision Procedure Versus Loop Procedure With Top Hat.

OBJECTIVE: To evaluate single-pass loop electrosurgical excision procedure (LEEP-SP) versus LEEP with top hat (LEEP-TH) in terms of treatment failure defined as high-grade squamous intraepithelial lesion (HSIL) cytology within 2 years' follow-up. METHODS: This single-institution cohort study used a prospectively collected cervical dysplasia database including all patients who underwent LEEP-SP or LEEP-TH for biopsy-proven cervical intraepithelial neoplasia between 2005 and 2019. RESULTS: Of 340 patients included, 178 underwent LEEP-SP and 162 LEEP-TH. The LEEP-TH patients were more likely to be older (mean age, 40.4 vs 36.5 years; p < .001) and have a positive preprocedure endocervical sampling (68.5% vs 11.8%; p < .001). Positive margins were found in 23 LEEP-SP (12.9%) and in 25 LEEP-TH (15.4%; p = .507). There was no significant difference in depth of excision between LEEP-SP (13.21 ± 23.19 mm) and LEEP-TH (17.37 ± 28.26 mm; p = .138). At 2 years, there was no difference in the rates of HSIL cytology (5.2% vs 6.3%; p = .698), any positive human papillomavirus test, or HSIL cytology (25% vs 15%; p = .284). The 57 patients undergoing repeat excision were more likely to be older (mean age, 40.95 vs 37.52 years; p = .023), have had a LEEP-TH (26.3% vs 73.7%; p < .001), and have initial cytologic HSIL (64.9% vs 35.0%; p < .001). CONCLUSIONS: In this single-institution study, there is no difference in the rate of recurrent HSIL in patients undergoing LEEP-SP versus LEEP-TH. A LEEP-TH may have limited additional benefit over a LEEP-SP in the treatment of cervical HSIL.

Gender Differences and Roles of Two Science Self-Efficacy Beliefs in Predicting Post-College Outcomes.

The end of college is a key transition point when students prepare for the workforce or graduate school, and when competence beliefs that have been shaped throughout college play a particularly important role in decision-making processes. This study examined the roles of two competence beliefs, self-efficacy for scientific tasks and science academic self-efficacy, during the final year of college. A structural equation model was used to examine science research self-efficacy and science academic self-efficacy as predictors of post-graduation science career intentions and life satisfaction; prior achievement was also included as a predictor of competence beliefs and post-graduation outcomes. Findings indicated that both types of self-efficacy predicted career intentions and life satisfaction. To better understand the processes that contribute to gender gaps in certain science careers, gender differences in mean levels of self-efficacy and in the structural relations among the variables of interest were examined using multi-group analyses. Females reported lower academic self-efficacy, despite having similar levels of prior achievement and outcomes; structural relations also appeared to vary by gender. Results extend theoretical understanding of the roles of two distinct forms of self-efficacy and the potential mechanisms explaining gender gaps in science fields.

Prioritizing Surgical Services during on-Going Pandemic Response: Modification and Reliability of the Medically Necessary Time Sensitive Surgery (MeNTS) Scoring Tool.

Health systems are struggling to manage a fluctuating volume of critically ill patients with COVID-19 while continuing to provide basic surgical services and expand capacity to address operative cases delayed by the pandemic. As we move forward through the next phases of the pandemic, we will need a decision-making system that allows us to remain nimble as clinicians to meet our patient's needs while also working with a new framework of healthcare operations. Here, we present our quality improvement process for the adaptation and application of the Medically Necessary Time-Sensitive (MeNTS) toolto gynecologic surgical services beyond the initial COVID response and into recovery of surgical services; with analysis of the reliability of the modified-MeNTS tool in our multi-site safety net hospital network. This multicenter study evaluated the gynecology surgical case volume at three tertiary acute care safety net institutions within the LA County Department of Health Services: Harbor-UCLA (HUMC), Olive View Medical Center (OVMC), and Los Angeles County + University of Southern California (LAC+USC). We describe our modified-Delphi approach to adapt the MeNTS tool in a structured fashion and its application to gynecologic surgical services. Blinded reviewers engaged in a three-round iterative adaptation and final scoring utilizing the modified tool. The cohort consisted of 392 female consecutive gynecology patients across three Los Angeles County Hospitals awaiting scheduled procedures in the surgical queue.The majority of patients were Latina (74.7%) and premenopausal (67.1%). Over half (52.4%) of the patients had cardiovascular disease, while 13.0% had lung disease, and 13.8% had diabetes. The most common indications for surgery were abnormal uterine bleeding (33.2%), pelvic organ prolapse (19.6%) and presence of an adnexal mass (14.3%). Minimally invasive approaches via laparoscopy, robotic-assisted laparoscopy, or vaginal surgery was the predominant planned surgical route (54.8%). Modified-MeNTS scores assumed a normal distribution across all patients within our cohort (Median 33, Range 18-52). Overall, ICC across all three institutions demonstrated "good" interrater reliability (0.72). ICC within institutions at HUMC and OVMC were categorized as "good" interrater reliability, while LAC-USC interrater reliability was categorized as "excellent" (HUMC 0.73, OVMC 0.65, LAC+USC 0.77). The modified-MeNTS tool performed well across a range of patients and procedures with a normal distribution of scores and high reliability between raters. We propose that the modified-MeNTS framework be considered as it employs quantitative methods for decision-making rather than subjective assessments.

The Role of Stereotype Threat in Ethnically Minoritized Students' Science Motivation: A Four-Year Longitudinal Study of Achievement and Persistence in STEM.

Grounded in expectancy-value and stereotype threat theories, this four-year longitudinal study examined associations between changes in stereotype threat and motivation (self-efficacy, task values, and perceived costs) among 425 undergraduates from racial/ethnic groups typically underrepresented in science, technology, engineering, and mathematics (STEM). Growth analyses indicated that students' stereotype threat and perceived cost of studying science increased during college, whereas science self-efficacy, intrinsic value, and attainment value declined. Parallel growth analyses suggested that higher initial stereotype threat related to a faster decline in attainment value and faster increase in perceived costs throughout college. Higher initial levels and a steeper increase in stereotype threat related to lower STEM GPA. Higher initial levels and a slower decline in motivation variables related to higher STEM GPA and more completed STEM courses. These findings provide empirical evidence for the relations between stereotype threat and motivation among underrepresented minority students during a key developmental period.

Development of an Online Experiment Platform for High School Biology.

We developed a novel online platform, Rex (Real experiments) that immerses students in a scientific investigative process. Rex is a virtual web-based biological science experiment platform, hosted by real scientists, and uses actual lab experiments that generate real data for students to collect, analyze, and interpret. Seven neuroscience experiments use zebrafish and rats as model systems to study the effects of drugs such as tetrahydrocannabinol (THC), caffeine, alcohol, and cigarette smoke, which are of interest to high school students. We carried out a small field-test of Rex in a variety of high school biology classrooms (e.g., standard, honors, AP, anatomy/physiology) to obtain student and teacher feedback about the implementation and usability of the program. We also assessed student situational interest (SI) to determine whether the Rex experiment captured students' attention, and whether it was an enjoyable and meaningful experience. Overall, students reported a moderate level of SI after participating in the Rex experiments. Situational interest did not differ across teachers, class section, class level, or the type of experiment. In addition, we present details of the technical issues encountered in the classroom, and we provide guidance to readers who may want to use the resource in their classrooms.

Science expectancy, value, and cost profiles and their proximal and distal relations to undergraduate science, technology, engineering, and math persistence.

Despite efforts to attract and maintain diverse students in the science, technology, engineering and math (STEM) pipeline, issues with attrition from undergraduate STEM majors persist. The aim of this study was to examine how undergraduate science students' competence beliefs, task values, and perceived costs in science combine into motivational profiles and to consider how such profiles relate to short and long-term persistence outcomes in STEM. We also examined the relations between underrepresented group membership and profile membership. Using latent profile analysis, we identified three profiles that characterized 600 participants' motivation during their first semester in college: Moderate All, Very High Competence/Values-Low Effort Cost, and High Competence/Values-Moderate Low Costs. The Moderate All profile was associated with the completion of fewer STEM courses and lower STEM GPAs relative to the other profiles after one year and after four years of college. Furthermore, underrepresented minority students were overrepresented in the Moderate All profile. Findings contribute to our understanding of how science competence beliefs, task values, and perceived costs may coexist and what combinations of these variables may be adaptive or deleterious for STEM persistence and achievement.

Measurements of the size and correlations between ions using an electrolytic point contact.

The size of an ion affects everything from the structure of water to life itself. In this report, to gauge their size, ions dissolved in water are forced electrically through a sub-nanometer-diameter pore spanning a thin membrane and the current is measured. The measurements reveal an ion-selective conductance that vanishes in pores <0.24 nm in diameter-the size of a water molecule-indicating that permeating ions have a grossly distorted hydration shell. Analysis of the current noise power spectral density exposes a threshold, below which the noise is independent of current, and beyond which it increases quadratically. This dependence proves that the spectral density, which is uncorrelated below threshold, becomes correlated above it. The onset of correlations for Li+, Mg2+, Na+ and K+-ions extrapolates to pore diameters of 0.13 ± 0.11 nm, 0.16 ± 0.11 nm, 0.22 ± 0.11 nm and 0.25 ± 0.11 nm, respectively-consonant with diameters at which the conductance vanishes and consistent with ions moving through the sub-nanopore with distorted hydration shells in a correlated way.

Science identity development trajectories in a gateway college chemistry course: Predictors and relations to achievement and STEM pursuit.

This investigation of undergraduates' heterogeneous science identity trajectories within a gateway chemistry course identified three latent classes (High and Stable, Moderate and Slightly Increasing, Moderate and Declining) using growth mixture modeling. Underrepresented minorities were more likely to exhibit Moderate-and-Slightly-Increasing science identities versus High-and-Stable patterns. Students with higher perceived competence were more likely classified into the High-and-Stable class compared to the other classes. Students classified into the High-and-Stable class scored significantly higher on the final exam and appeared to be more likely to remain in a STEM major across fall and spring semesters compared to the other two classes. Results suggest that some students' identities shift within a single semester and supporting science perceived competence before college may support students' science identity development.

Multiple Pathways to Success: An Examination of Integrative Motivational Profiles Among Upper Elementary and College Students.

Two studies were conducted with distinct samples to investigate how motivational beliefs cohere and function together (i.e., motivational profiles) and predict academic adjustment. Integrating across motivational theories, participants (N Study 1 = 160 upper elementary students; N Study 2 = 325 college students) reported on multiple types of motivation (achievement goals, task value, perceived competence) for schooling more generally (Study 1) and in science (Study 2). Three profiles characterized by Moderate-High All, Intrinsic and Confident, and Average All motivation were identified in both studies. Profiles characterized by Very High All motivation (Study 1) and Moderate Intrinsic and Confident (Study 2) were also present. Across studies, the Moderate-High All and Intrinsic and Confident profiles were associated with the highest academic engagement and achievement. Findings highlight the benefit of integrating across motivational theories when creating motivational profiles, provide initial evidence regarding similarities and differences in integrative motivational profiles across distinct samples, and identify which motivational combinations are associated with beneficial academic outcomes in two educational contexts.

From science student to scientist: Predictors and outcomes of heterogeneous science identity trajectories in college.

This 5-year longitudinal study investigates the development of science identity throughout college from an expectancy-value perspective. Specifically, heterogeneous developmental patterns of science identity across 4 years of college were examined using growth-mixture modeling. Gender, race/ethnicity, and competence beliefs (efficacy for science tasks, perceived competence in science) were modeled as antecedents, and participation in a science career after graduation was modeled as a distal outcome of these identity development trajectories. Three latent classes (High with Transitory Incline, Moderate-High and Stable, and Moderate-Low with Early Decline) were identified. Gender, race/ethnicity, and competence beliefs in the first year of college significantly predicted latent class membership. In addition, students in the two highest classes were significantly more likely to report being involved in science careers or science fields after college graduation than students in the Moderate-Low with Early Decline class. (PsycINFO Database Record

Repairing the Leaky Pipeline: A Motivationally Supportive Intervention to Enhance Persistence in Undergraduate Science Pathways.

The current study reports on the efficacy of a multi-faceted motivationally designed undergraduate enrichment summer program for supporting science, technology, engineering and math (STEM) persistence. Structural equation modeling was used to compare summer program participants (n = 186), who participated in the program between their first and second years in college, to a propensity score matched comparison sample (n = 401). Participation in the summer program positively predicted science motivation (self-efficacy, task value), assessed eight months after the end of the program (second year in college). The summer enrichment program was also beneficial for science persistence variables, as evidenced by significant direct and indirect effects of the program on science course completion during students' third year of college and students' intentions to pursue a science research career assessed during the third year of college. In general, the program was equally beneficial for all participants, but ancillary analyses indicated added benefits with respect to task value for students with relatively lower prior science achievement during the first year of college and with respect to subsequent science course taking for males. Implications for developing effective interventions to reduce the flow of individuals out of STEM fields and for translating motivational theory into practice are discussed.

A Pharmacology-Based Enrichment Program for Undergraduates Promotes Interest in Science.

There is a strong need to increase the number of undergraduate students who pursue careers in science to provide the "fuel" that will power a science and technology-driven U.S. economy. Prior research suggests that both evidence-based teaching methods and early undergraduate research experiences may help to increase retention rates in the sciences. In this study, we examined the effect of a program that included 1) a Summer enrichment 2-wk minicourse and 2) an authentic Fall research course, both of which were designed specifically to support students' science motivation. Undergraduates who participated in the pharmacology-based enrichment program significantly improved their knowledge of basic biology and chemistry concepts; reported high levels of science motivation; and were likely to major in a biological, chemical, or biomedical field. Additionally, program participants who decided to major in biology or chemistry were significantly more likely to choose a pharmacology concentration than those majoring in biology or chemistry who did not participate in the enrichment program. Thus, by supporting students' science motivation, we can increase the number of students who are interested in science and science careers.

Antecedents and consequences of situational interest.

BACKGROUND: There is a growing body of research on situational interest (SI). Yet, we still know relatively little about how SI is supported in the classroom and the academic benefits of SI. AIM: The current study investigated (1) contextual antecedents of SI; (2) potential benefits of SI for academic outcomes; and (3) SI as a mediator of classroom practices to academic outcomes. SAMPLE: Participants were 126 male and female adolescents (mean age = 14.6 years) who took part in a science course during a 3-week residential summer programme for talented adolescents. METHOD: Participants completed self-report measures prior to the start of the summer programme and at the end of the programme. Summer programme instructors completed ratings of students' engagement during the programme. RESULT: Multiple regression analyses were conducted to investigate the three study aims. After controlling for initial individual interest, perceived choice, instructor approachability, and course connections to real life were statistically significant predictors of SI during the summer programme, with varying associations observed based on the form of SI (triggered, maintained-feeling, and maintained-value). SI was positively related to individual interest and perceived competence in science at the end of the programme as well as teacher-rated engagement; SI also mediated the associations of classroom practices with these outcomes. CONCLUSION: Results suggest that classroom practices shape SI. In turn, SI supports motivation and engagement. Moreover, differentiated antecedents and outcomes of the three sub-components of SI were identified, highlighting the utility of this three-component approach for studying SI.

Identification as Gifted and Implicit Beliefs About Intelligence: An Examination of Potential Moderators.

The current study investigated whether the developmental timing of a student's identification as gifted (i.e., when a student is first identified) was associated with later implicit beliefs about intelligence, and whether this relation is moderated by academic ability. A sample of 1,743 high-ability college students reported on whether and when they had been identified as gifted, academic ability (SAT scores), and implicit beliefs of intelligence. Timing of identification was unrelated to implicit beliefs; academic ability was the only significant predictor. Higher ability students who had been previously identified as gifted at any point in time reported implicit beliefs more toward entity beliefs than relatively lower ability students who had also been identified; however, this effect was quite small. Implicit beliefs did not vary by ability level for nonidentified students. These findings suggest that identification as gifted at any age modestly (but not necessarily meaningfully) relates to implicit beliefs for high-ability students.

Symposium on integrating the science of environmental justice into decision-making at the Environmental Protection Agency: an overview.

In March 2010, the Environmental Protection Agency (EPA) collaborated with government and nongovernmental organizations to host a groundbreaking symposium, "Strengthening Environmental Justice Research and Decision Making: A Symposium on the Science of Disproportionate Environmental Health Impacts." The symposium provided a forum for discourse on the state of scientific knowledge about factors identified by EPA that may contribute to higher burdens of environmental exposure or risk in racial/ethnic minorities and low-income populations. Also featured were discussions on how environmental justice considerations may be integrated into EPA's analytical and decision-making frameworks and on research needs for advancing the integration of environmental justice into environmental policymaking. We summarize key discussions and conclusions from the symposium and briefly introduce the articles in this issue.