1,059 research outputs found

    Automation and robotics considerations for a lunar base

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    An envisioned lunar outpost shares with other NASA missions many of the same criteria that have prompted the development of intelligent automation techniques with NASA. Because of increased radiation hazards, crew surface activities will probably be even more restricted than current extravehicular activity in low Earth orbit. Crew availability for routine and repetitive tasks will be at least as limited as that envisioned for the space station, particularly in the early phases of lunar development. Certain tasks are better suited to the untiring watchfulness of computers, such as the monitoring and diagnosis of multiple complex systems, and the perception and analysis of slowly developing faults in such systems. In addition, mounting costs and constrained budgets require that human resource requirements for ground control be minimized. This paper provides a glimpse of certain lunar base tasks as seen through the lens of automation and robotic (A&R) considerations. This can allow a more efficient focusing of research and development not only in A&R, but also in those technologies that will depend on A&R in the lunar environment

    Secondary Students' Dynamic Modeling Processes: Analyzing, Reasoning About, Synthesizing, and Testing Models of Stream Ecosystems

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    In this paper, we explore dynamic modeling as an opportunity for students to think about the science content they are learning. We examined the “Cognitive Strategies for Modeling” (CSMs) in which students engaged as they created dynamic models. We audio- and videotape-recorded eight pairs of ninth grade science students and analyzed their conversations and actions. In analyzing appropriate objects and factors for their model, some students merely enumerated potential factors whereas others engaged in rich, substantial, mindful analysis. In reasoning about their models, students discussed relationships in depth, concentrated only on the most important key relationships, or encountered difficulty distinguishing between causal and correlational relationships. In synthesizing working models, students mapped their model to aid visualization, focused on their goal, or talked about their model's appearance or form. Students attempted to articulate explanations for their relationships, but sometimes their explanations were shallow. In testing their models, some students tested thoroughly but only a few persisted in debugging their model's behavior so that it matched their expectations. In our conclusion we suggest that creating dynamic models has great potential for use in classrooms to engage students in thought about science content, particularly in those thinking strategies best fostered by dynamic modeling: analysis, relational reasoning, synthesis, testing and debugging, and making explanations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45184/1/10956_2004_Article_412477.pd

    Standardized test outcomes for students engaged in inquiry-based science curricula in the context of urban reform

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    Considerable effort has been made over the past decade to address the needs of learners in large urban districts through scaleable reform initiatives. We examine the effects of a multifaceted scaling reform that focuses on supporting standards based science teaching in urban middle schools. The effort was one component of a systemic reform effort in the Detroit Public Schools, and was centered on highly specified and developed project-based inquiry science units supported by aligned professional development and learning technologies. Two cohorts of 7th and 8th graders that participated in the project units are compared with the remainder of the district population, using results from the high-stakes state standardized test in science. Both the initial and scaled up cohorts show increases in science content understanding and process skills over their peers, and significantly higher pass rates on the statewide test. The relative gains occur up to a year and a half after participation in the curriculum, and show little attenuation with in the second cohort when scaling occurred and the number of teachers involved increased. The effect of participation in units at different grade levels is independent and cumulative, with higher levels of participation associated with similarly higher achievement scores. Examination of results by gender reveals that the curriculum effort succeeds in reducing the gender gap in achievement experienced by urban African-American boys. These findings demonstrate that standards-based, inquiry science curriculum can lead to standardized achievement test gains in historically underserved urban students, when the curriculum is highly specified, developed, and aligned with professional development and administrative support. © 2008 Wiley Periodicals, Inc. J Res Sci Teach 45: 922–939, 2008Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/61206/1/20248_ftp.pd

    BlackOPs: Increasing confidence in variant detection through mappability filtering

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    Identifying variants using high-throughput sequen-cing data is currently a challenge because true biological variants can be indistinguishable from technical artifacts. One source of technical arti-fact results from incorrectly aligning experimen-tally observed sequences to their true genomic origin (‘mismapping’) and inferring differences in mismapped sequences to be true variants. We de-veloped BlackOPs, an open-source tool that simu-lates experimental RNA-seq and DNA whole exome sequences derived from the reference genome, aligns these sequences by custom parameters, detects variants and outputs a blacklist of positions and alleles caused by mismapping. Blacklist

    Site-specific inductive and inhibitory activities of MMP-2 and MMP-3 orchestrate mammary gland branching morphogenesis

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    During puberty, mouse mammary epithelial ducts invade the stromal mammary fat pad in a wave of branching morphogenesis to form a complex ductal tree. Using pharmacologic and genetic approaches, we find that mammary gland branching morphogenesis requires transient matrix metalloproteinase (MMP) activity for invasion and branch point selection. MMP-2, but not MMP-9, facilitates terminal end bud invasion by inhibiting epithelial cell apoptosis at the start of puberty. Unexpectedly, MMP-2 also represses precocious lateral branching during mid-puberty. In contrast, MMP-3 induces secondary and tertiary lateral branching of ducts during mid-puberty and early pregnancy. Nevertheless, the mammary gland is able to develop lactational competence in MMP mutant mice. Thus, specific MMPs refine the mammary branching pattern by distinct mechanisms during mammary gland branching morphogenesis

    Orthotopic Ileal Neobladder Reconstruction for Bladder Cancer: Is Adjuvant Chemotherapy Safe?

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    ABSTRACT Objective: We examined our database of patients undergoing radical cystectomy (RC) with orthotopic neobladder (NB) to determine whether adjuvant chemotherapy in this group is safe. Materials and Methods: We performed a retrospective analysis of patients who underwent radical cystectomy and urinary diversion between 1992 and 2004. Relevant clinical and therapeutic data were entered into a database. High-risk bladder cancer patients who underwent NB were identified. They were stratified into 2 groups, those who received adjuvant chemotherapy and those who did not. The incidence of complications between the 2 groups was analyzed and compared. Results: Over the 12-year period, 136 patients underwent RC and NB construction for bladder cancer. Of these, 83 patients were at high risk for recurrence. Nineteen patients received adjuvant chemotherapy and 64 did not. The complication rate in the adjuvant chemotherapy group was 53% and it was 23% in those who did not receive chemotherapy. There were no perioperative or treatment related death. There were 2 patients with grade 4 toxicity in the adjuvant chemotherapy group. There was a statistical difference between these two groups with regard to the incidence of complications. However, none of these complications was life-threatening, required only conservative treatment and caused no long-term disability. Conclusions: Adjuvant chemotherapy is a safe treatment for patients undergoing RC and NB substitution. Hence, the option of orthotopic NB should not be denied in selected bladder cancer patients with high risk for recurrent disease

    An Investigation of Software Scaffolds Supporting Modeling Practices

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    Modeling of complex systems and phenomena is of value in science learning and is increasingly emphasised as an important component of science teaching and learning. Modeling engages learners in desired pedagogical activities. These activities include practices such as planning, building, testing, analysing, and critiquing. Designing realistic models is a difficult task. Computer environments allow the creation of dynamic and even more complex models. One way of bringing the design of models within reach is through the use of scaffolds. Scaffolds are intentional assistance provided to learners from a variety of sources, allowing them to complete tasks that would otherwise be out of reach. Currently, our understanding of how scaffolds in software tools assist learners is incomplete. In this paper the scaffolds designed into a dynamic modeling software tool called Model-It are assessed in terms of their ability to support learners' use of modeling practices. Four pairs of middle school students were video-taped as they used the modeling software for three hours, spread over a two week time frame. Detailed analysis of coded videotape transcripts provided evidence of the importance of scaffolds in supporting the use of modeling practices. Learners used a variety of modeling practices, the majority of which occurred in conjunction with scaffolds. The use of three tool scaffolds was assessed as directly as possible, and these scaffolds were seen to support a variety of modeling practices. An argument is made for the continued empirical validation of types and instances of tool scaffolds, and further investigation of the important role of teacher and peer scaffolding in the use of scaffolded tools.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43636/1/11165_2004_Article_5112115.pd

    Integrated analysis of RNA and DNA from the phase III trial CALGB 40601 identifies predictors of response to trastuzumab-based neoadjuvant chemotherapy in HER2-positive breast cancer

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    Purpose: Response to a complex trastuzumab-based regimen is affected by multiple features of the tumor and its microenvironment. Developing a predictive algorithm is key to optimizing HER2-targeting therapy. Experimental Design: We analyzed 137 pretreatment tumors with mRNA-seq and DNA exome sequencing from CALGB 40601, a neoadjuvant phase III trial of paclitaxel plus trastuzumab with or without lapatinib in stage II to III HER2-positive breast cancer. We adopted an Elastic Net regularized regression approach that controls for covarying features within high-dimensional data. First, we applied 517 known gene expression signatures to develop an Elastic Net model to predict pCR, which we validated on 143 samples from four independent trials. Next, we performed integrative analyses incorporating clinicopathologic information with somatic mutation status, DNA copy number alterations (CNA), and gene signatures. Results: The Elastic Net model using only gene signatures predicted pCR in the validation sets (AUC ¼ 0.76). Integrative analyses showed that models containing gene signatures, clinical features, and DNA information were better pCR predictors than models containing a single data type. Frequently selected variables from the multiplatform models included amplifications of chromosome 6p, TP53 mutation, HER2-enriched subtype, and immune signatures. Variables predicting resistance included Luminal/ERþ features. Conclusions: Models using RNA only, as well as integrated RNA and DNA models, can predict pCR with improved accuracy over clinical variables. Somatic DNA alterations (mutation, CNAs), tumor molecular subtype (HER2E, Luminal), and the microenvironment (immune cells) were independent predictors of response to trastuzumab and paclitaxel-based regimens. This highlights the complexity of predicting response in HER2-positive breast cancer

    Regioselective routes to orthogonally-substituted aromatic MIDA boronates

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    A series of tetrasubstituted aromatics has been synthesized, many of which are based on elaborated N-methyliminodiacetic acid (MIDA)-boronates. A sequence employing nitration, bromination, stepwise Suzuki-Miyaura (SM) coupling with a boronic acid, then base-mediated unmasking of the boronic acid from the MIDA-boronate and a second SM-coupling has led to our desired, mainly 1,2,4,5-substituted tetrasubstituted aromatic targets
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