The Stellar Masses and Star Formation Histories of Galaxies at z ≈ 6: Constraints from Spitzer Observations in the Great Observatories Origins Deep Survey

Using the deep Spitzer Infrared Array Camera (IRAC) observations of the Great Observatories Origins Deep Survey (GOODS), we study the stellar masses and star formation histories of galaxies at z approx 6 based on the i_(775)-band dropout sample selected from the GOODS fields. In total, we derive stellar masses for 53 i_(775)-band dropouts that have robust IRAC detections. These galaxies have typical stellar masses of ~10^(10) M_⊙ and typical ages of a couple of hundred million years, consistent with earlier results based on a smaller sample of z ≈ 6 galaxies. The existence of such massive galaxies at z ≈ 6 can be explained by at least one set of N-body simulations of the hierarchical paradigm. We also study 79 i_(775)-band dropouts that are invisible in the IRAC data and find that they are typically less massive by a factor of 10. These galaxies are much bluer than those detected by the IRAC, indicating that their luminosities are dominated by stellar populations with ages ≾ 40 Myr. Based on our mass estimates, we derive a lower limit to the global stellar mass density at z ≈ 6, which is 1.1-6.7 × 10^6 M_⊙ Mpc^(-3). The prospect of detecting the progenitors of the most massive galaxies at yet higher redshifts is explored. We also investigate the implication of our results for reionization and find that the progenitors of the galaxies comparable to those in our sample, even in the most optimized (probably unrealistic) scenario, cannot sustain the reionization for a period longer than ~2 Myr. Thus most of the photons required for reionization must have been provided by other sources, such as the progenitors of the dwarf galaxies that are far below our current detection capability

Impact of Training and Education for Caregivers of Infants and Toddlers

Training and education of infant and toddler caregivers is one important factor associated with the quality of child care they provide. In response to research showing that high-quality care supports positive development in young children, policymakers have established training and education requirements for licensed providers and launched numerous initiatives to train and educate caregivers. Caregivers themselves believe training and education to be important, including relative and unregulated family child care providers, many of whom express interest in accessing training although not required by regulation to do so. What approaches to caregiver training and education are the most likely to improve the quality of care for children under age 3 in family child care homes and centers? To help answer this question, this brief describes research findings on a small number of training initiatives targeting infant and toddler caregivers where quality was observed before and after training. While it is too soon to draw firm generalizations from this young and scattered body of research, findings from these studies raise pertinent considerations for policymakers. (See Research-to-Policy Connections No. 2, Infant and Toddler Child Care Quality, for a list of observational instruments frequently used to measure quality.) Other research has focused on increases in provider knowledge and/or self-reported changes in caregiving practices as a result of training and education. It is not clear whether effects found using either of these measures correspond to effects on quality seen with observational measures

Infant and Toddler Child Care Quality

With over half the nation's infants and toddlers in regular, nonparental child care, the quality of that care is a priority concern for policymakers. Many studies show that high-quality child care supports the positive social, emotional, and cognitive development of young children. The research summarized in this policy brief identifies factors that tend to predict higher quality within arrangement types—family child care, center care, and relative care—and describes the range of quality found in each type. Although different studies measure child care quality in different ways, many researchers group quality measures into two categories, structural and process. Both examine factors that support the responsive and reliable relationships with caregivers so essential for the healthy development of infants and toddlers. Structural measures—child-staff ratio and group size, caregivers' general education and specialized training, their tenure and income—look at aspects of arrangements that support positive child-adult relationships and child development. Process measures directly examine children's experiences, including caregivers' interactions with the children—their attention, warmth, and responsiveness. Though less direct, structural factors are less costly for researchers to study than process factors, which require direct observations. Unlike process factors, structural factors can be regulated by policymakers. Many instruments are used to measure quality in infant and toddler child care arrangements (see the Resources Section for a list of frequently use ones). Most are designed to examine the global quality of child care arrangements—producing a composite rating based on observations of routines, practices, facilities, and equipment—and utilize both process and structural measures. Some are more exclusively composed of process measures. Researchers continue to develop new measures and instruments in this young field of inquiry

Infant and Toddler Child Care Arrangements

What care arrangements do American parents make for their infants and toddlers while they are at work, school, or otherwise unavailable to provide care themselves? Research findings that respond to this question come from two recent nationally representative surveys: the Early Childhood Longitudinal Study, Birth Cohort, and the National Survey of America's Families (NSAF), 2002. Additional research helps answer a second, related question: What factors influence the types of care arrangements made for this country's children under age 3

Experimental studies of the vapor phase nucleation of refractory compounds. VI. The condensation of sodium.

In this paper we discuss the condensation of sodium vapor and the formation of a sodium aerosol as it occurs in a gas evaporation condensation chamber. A one-dimensional model describing the vapor transport to the vapor/aerosol interface was employed to determine the onset supersaturation, in which we assume the observed location of the interface is coincident with a nucleation rate maximum. We then present and discuss the resulting nucleation onset supersaturation data within the context of nucleation theory based on the liquid droplet model. Nucleation results appear to be consistent with a cesium vapor-to-liquid nucleation study performed in a thermal diffusion cloud chamber

Exploring More-Coherent Quantum Annealing

In the quest to reboot computing, quantum annealing (QA) is an interesting candidate for a new capability. While it has not demonstrated an advantage over classical computing on a real-world application, many important regions of the QA design space have yet to be explored. In IARPA's Quantum Enhanced Optimization (QEO) program, we have opened some new lines of inquiry to get to the heart of QA, and are designing testbed superconducting circuits and conducting key experiments. In this paper, we discuss recent experimental progress related to one of the key design dimensions: qubit coherence. Using MIT Lincoln Laboratory's qubit fabrication process and extending recent progress in flux qubits, we are implementing and measuring QA-capable flux qubits. Achieving high coherence in a QA context presents significant new engineering challenges. We report on techniques and preliminary measurement results addressing two of the challenges: crosstalk calibration and qubit readout. This groundwork enables exploration of other promising features and provides a path to understanding the physics and the viability of quantum annealing as a computing resource.Comment: 7 pages, 3 figures. Accepted by the 2018 IEEE International Conference on Rebooting Computing (ICRC

Usability and feasibility of consumer-facing technology to reduce unsafe medication use by older adults

Background Mobile health technology can improve medication safety for older adults, for instance, by educating patients about the risks associated with anticholinergic medication use. Objective This study's objective was to test the usability and feasibility of Brain Buddy, a consumer-facing mobile health technology designed to inform and empower older adults to consider the risks and benefits of anticholinergics. Methods Twenty-three primary care patients aged ≥60 years and using anticholinergic medications participated in summative, task-based usability testing of Brain Buddy. Self-report usability was assessed by the System Usability Scale and performance-based usability data were collected for each task through observation. A subset of 17 participants contributed data on feasibility, assessed by self-reported attitudes (feeling informed) and behaviors (speaking to a physician), with confirmation following a physician visit. Results Overall usability was acceptable or better, with 100% of participants completing each Brain Buddy task and a mean System Usability Scale score of 78.8, corresponding to “Good” to “Excellent” usability. Observed usability issues included higher rates of errors, hesitations, and need for assistance on three tasks, particularly those requiring data entry. Among participants contributing to feasibility data, 100% felt better informed after using Brain Buddy and 94% planned to speak to their physician about their anticholinergic related risk. On follow-up, 82% reported having spoken to their physician, a rate independently confirmed by physicians. Conclusion Consumer-facing technology can be a low-cost, scalable intervention to improve older adults’ medication safety, by informing and empowering patients. User-centered design and evaluation with demographically heterogeneous clinical samples uncovers correctable usability issues and confirms the value of interventions targeting consumers as agents in shared decision making and behavior change

Post-Agricultural Succession in El PetÉn, Guatemala

We compared post-agricultural succession across the range of farming activities practiced in Guatemala's northern lowlands: agroforestry, swidden, ranching, and input-intensive monocultures. At 10 sites over 13 to 40 months we assessed the following characteristics of trees and shrubs that were>1 cm diameter at breast height: height, basal-area accumulation, recruitment of all individuals and fleshy-fruited individuals, and accumulation of all species and fleshy-fruited species. Succession, as measured by all these response variables except height, was dramatically faster on agroforestry and swidden sites than on pastures or input-intensive monocultures. Overall recruitment was faster for swiddens than for agroforests, but other response variables did not differ significantly between the two treatments. Regression results suggest that initial ground cover by herbs inhibited recruitment of woody colonists. The significant positive coefficient for initial basal area and the significant negative coefficient for distance from forest for accumulation of both fleshy-fruited individuals and species are probably explained by the behavioral responses of seed-dispersing animals. Our results suggest that the conservation strategy of discouraging swidden agriculture in favor of sedentary, input-intensive agriculture to relieve pressure on old-growth forest may be counterproductive over the long term.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75095/1/j.1523-1739.2003.01265.x.pd

Board # 114 : Progress toward Optimizing Student Team Skill Development using Evidence-Based Strategies

The broad goal of this work is to study the effectiveness of various teamwork training interventions. This research requires the use of a common model of teamwork and a system for training, collecting ratings data, and providing feedback. We will leverage the NSF’s prior investment in the CATME system, which meets the research criteria and automates some of the data collection and feedback, which will aid in executing the research protocol consistently. Seven empirical studies will determine the effect sizes of training, practice in teams, practice rating, and feedback interventions on cognitive development (improvement of team skills) and metacognitive development (improvement of self- and peer-evaluation skills). Outcomes. We focus both on cognitive skills related to team-member effectiveness and on metacognitive skills that enable competent self- and peer-evaluation of team members’ effectiveness. An intermediate knowledge-level outcome affects both—developing an improved cognitive model of teamwork. Students must learn what skills are necessary for effective teamwork to be able to develop and evaluate them. Strategies. To achieve these outcomes, we have several strategies. Frame-of-reference training, which is well-established and empirically supported, will align students’ cognitive model of teamwork with ours by teaching students the ways team members can contribute effectively to teams in the five key areas summarized earlier. Experience working in teams and evaluating teamwork will improve team skills and self- and peer-evaluation skills. Experience in teams increases as students work on multiple teams. Rating practice will be accomplished by showing students descriptions or videotapes of fictitious team members and having them rate the contributions these fictitious team members make, in addition to rating themselves and their real teammates following work in teams. Finally, we will examine how the degree to which and manner in which feedback on team skills is provided affect student outcomes. This presentation (Executive Summary and Poster) will provide a valuable update on this project, share various lessons for classroom practice, and provide guidance to other faculty who seek to use CATME in their research

Application of scaled nucleation theory to metallic vapor condensation

In this paper we report that scaled nucleation theory (SNT) can describe moderately well the observed nucleation behavior of a significant number of refractory materials if a more appropriate value of a quantity commonly referred to as the excess surface entropy is used. With the availability of more reliable critical point and liquid property data, we are better able to calculate this quantity and we find that for refractory materials it can be as small as one half to one third the quantity traditionally used in its approximation. As a result of using more accurate values, we find considerably better agreement between SNT and experiment than what was originally determined. We also explain why using surface tension slope information to determine the excess surface entropy can lead to substantial errors in the SNT supersaturation prediction