862 research outputs found

    Status and egalitarianism in traditional communities: An analysis of funeral attendance in six Zimbabwean villages

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    This paper explores two hypotheses concerning the role of status in relationships between rich and poor in traditional communities by analyzing who goes to whose funerals in six Zimbabwean villages. Funerals allow status to be observed because non-attendance is a sign of disrespect. We find that the richer a household hosting a funeral, the less likely heads of neighbouring households are to attend. Thus, the status-for0insurance hypothesis - that the poor bestow status upon the rich in return for help in times of need is rejected in favour of the egalitarianism hypothesis - that richer households are denied status.

    An Up-Close Look at Student-Centered Math Teaching: A Study of Highly Regarded High School Teachers and Their Students - Executive Summary

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    Today, far too many students see mathematics as a subject to be endured, rather than a subject of real-world importance and personal value. That doesn't have to be the case. When teachers use student-centered techniques to engage studentsin more active and authentic ways, they can transform math classrooms into lively learning environments in which studentstake charge of their own learning, collaborate with others, persist in solving complex problems, and make meaningfulconnections to the world around them. Through such experiences, students may come to appreciate mathematics as adiscipline that enriches their lives and their understanding of the world.While a growing body of research supports many of the principles of student-centered instruction, there is still a great dealto learn about how such approaches enhance student learning in mathematics. Recent calls for strengthening the STEMworkforce and for more rigorous K-12 standards via the Common Core State Standards have placed increased emphasison developing higher-order thinking and problem-solving skills in high school mathematics, heightening the need for moreinformation about how teachers can effectively engage students with math content.The American Institutes of Research (AIR), with support from the Nellie Mae Education Foundation, conducted a study ofhighly regarded high school math teachers to expand the research base in two important ways. First, rather than assumingstudent-centered instruction is a monolithic construct, the team used a case study approach to provide rich descriptions ofhow the approach plays out in several classrooms, taking into account how teachers' personal philosophy and the school'sinstructional context might influence their practice. The case study also provided insights into students' perspectives on different approaches to mathematics instruction. Second, the researchers look across a larger sample of classrooms to determine the effects of varying degrees of student-centeredness on students' engagement with learning and their problem-solving skills.This brief offers highlights from the study's design and findings. Readers are encouraged to access the full paper for more details

    The Deformable Mirror Demonstration Mission (DeMi) CubeSat: optomechanical design validation and laboratory calibration

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    Coronagraphs on future space telescopes will require precise wavefront correction to detect Earth-like exoplanets near their host stars. High-actuator count microelectromechanical system (MEMS) deformable mirrors provide wavefront control with low size, weight, and power. The Deformable Mirror Demonstration Mission (DeMi) payload will demonstrate a 140 actuator MEMS deformable mirror (DM) with \SI{5.5}{\micro\meter} maximum stroke. We present the flight optomechanical design, lab tests of the flight wavefront sensor and wavefront reconstructor, and simulations of closed-loop control of wavefront aberrations. We also present the compact flight DM controller, capable of driving up to 192 actuator channels at 0-250V with 14-bit resolution. Two embedded Raspberry Pi 3 compute modules are used for task management and wavefront reconstruction. The spacecraft is a 6U CubeSat (30 cm x 20 cm x 10 cm) and launch is planned for 2019.Comment: 15 pages, 10 figues. Presented at SPIE Astronomical Telescopes + Instrumentation, Austin, Texas, US

    Understanding the Antiproliferative Activity of Plant Extracts

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    Many plants possess medicinal properties. Some, such as the Pacific yew, have yielded chemotherapeutic drugs (taxanes). Scientists report that other extracts such as the leaves of Calendula officinalis (marigold), Vinca rosea (periwinkle), Viscum cruciatum (mistletoe), and Rosmarinus officinalis (rosemary) have anti-tumor activity. In most cases, the chemical components responsible for antiproliferative activity have not been identified and it is unclear if any individual components are as effective in isolation as they are in the context of the whole extract. Furthermore, in most cases, there are no data indicating whether these extracts have synergistic effects or cause negative reactions when used with other drugs. We are using HeLa (adenocarcinoma), RAW 264.7 (leukemia), HepG2 (hepatoma), MDA-MB-231 (adenocarcinoma), and human foreskin fibroblasts (HFF, non-tumorigenic) to test the antiproliferative activity of several plant extracts. We identified five extracts, grapeseed, guava, yew, juniper berry, and Vinca, that slow the growth of all five cell lines in a dose-dependent manner. We are using a variety of methods to understand the mechanism by which these extracts are blocking cell growth

    Regional Structural Orientation of the Mount Sharp Group Revealed by In Situ Dip Measurements and Stratigraphic Correlations on the Vera Rubin Ridge

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    Ground‐based bedding orientation measurements are critical to determine the geologic history and processes of sedimentation in Gale crater, Mars. We constrain the dip of lacustrine strata of the Blunts Point, Pettegrove Point, and Jura members of the Murray formation using a combination of regional stratigraphic correlations and bed attitude measurements from stereo Mastcam images taken by the Mars Science Laboratory Curiosity rover. In situ bed attitude measurements using a principal component analysis‐based regression method reveal a wide range of dips and dip azimuths owing to a combination of high stereo errors, postdepositional deformation of strata (e.g., fracturing, rotation, and impact cratering), and different primary depositional dips. These constrain regional dips to be within several degrees of horizontal on average. Stratigraphic correlations between targets observed in the Glen Torridon trough and at the Pettegrove Point‐Jura member contact of Vera Rubin ridge (VRR) constrain dips to be between 3°SE and 2°NW, consistent with nearly flat strata deposited horizontally on an equipotential surface. The Jura member is determined to be stratigraphically equivalent to the northern portion of the Glen Torridon trough. Rover‐based dip magnitudes are generally significantly shallower than the orientation of VRR member contacts measured from High Resolution Imaging Science Experiment‐based traces, suggesting the sedimentary strata and VRR member contacts may be discordant

    Genetic Decomposition of the Heritable Component of Reported Childhood Maltreatment

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    BACKGROUND: Decades of research have shown that environmental exposures, including self-reports of trauma, are partly heritable. Heritable characteristics may influence exposure to and interpretations of environmental factors. Identifying heritable factors associated with self-reported trauma could improve our understanding of vulnerability to exposure and the interpretation of life events. METHODS: We used genome-wide association study summary statistics of childhood maltreatment, defined as reporting of abuse (emotional, sexual, and physical) and neglect (emotional and physical) (N = 185,414 participants). We calculated genetic correlations (rg) between reported childhood maltreatment and 576 traits to identify phenotypes that might explain the heritability of reported childhood maltreatment, retaining those with |rg| > 0.25. We specified multiple regression models using genomic structural equation modeling to detect residual genetic variance in childhood maltreatment after accounting for genetically correlated traits. RESULTS: In 2 separate models, the shared genetic component of 12 health and behavioral traits and 7 psychiatric disorders accounted for 59% and 56% of heritability due to common genetic variants (single nucleotide polymorphism–based heritability [h2SNP]) of childhood maltreatment, respectively. Genetic influences on h2SNP of childhood maltreatment were generally accounted for by a shared genetic component across traits. The exceptions to this were general risk tolerance, subjective well-being, posttraumatic stress disorder, and autism spectrum disorder, identified as independent contributors to h2SNP of childhood maltreatment. These 4 traits alone were sufficient to explain 58% of h2SNP of childhood maltreatment. CONCLUSIONS: We identified putative traits that reflect h2SNP of childhood maltreatment. Elucidating the mechanisms underlying these associations may improve trauma prevention and posttraumatic intervention strategies

    Microwave Spin Control of a Tin-Vacancy Qubit in Diamond

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    The negatively charged tin-vacancy (SnV-) center in diamond is a promising solid-state qubit for applications in quantum networking due to its high quantum efficiency, strong zero phonon emission, and reduced sensitivity to electrical noise. The SnV- has a large spin-orbit coupling, which allows for long spin lifetimes at elevated temperatures, but unfortunately suppresses the magnetic dipole transitions desired for quantum control. Here, by use of a naturally strained center, we overcome this limitation and achieve high-fidelity microwave spin control. We demonstrate a pi-pulse fidelity of up to 99.51+/0.03%$ and a Hahn-echo coherence time of T2echo = 170.0+/-2.8 microseconds, both the highest yet reported for SnV- platform. This performance comes without compromise to optical stability, and is demonstrated at 1.7 Kelvin where ample cooling power is available to mitigate drive induced heating. These results pave the way for SnV- spins to be used as a building block for future quantum technologies

    The Lantern Vol. 76, No. 1, Fall 2008

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    • Cruel • A Night in Three Parts • The Moment I Said It • To Know • I Will Never Skipskipskip a Rock • The Ravine • Untitled • Skeleton • Midnight Letter • Where Children Come From • Orphan of War • Ciega / Mezquita • The Other Side • Those Dancing Days are Gone • Cycling • The 2nd of July • The Tantric Semantics of Studying Abroad • A Three-Part Study in Musical Relations • Amway Man • Hard Luck Investigator • Spring • Interview With Poet Eleanor Wilnerhttps://digitalcommons.ursinus.edu/lantern/1173/thumbnail.jp
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