1,116 research outputs found
Policy Analysis: Minimum Wage in the Portland Metropolitan Area
Oregon’s current minimum wage of 14.75 in 2022. This wage provides full time minimum wage workers enough income for adequate nutrition and reasonable housing while reducing reliance on social safety net programs
Seconds-scale coherence in a tweezer-array optical clock
Optical clocks based on atoms and ions achieve exceptional precision and
accuracy, with applications to relativistic geodesy, tests of relativity, and
searches for dark matter. Achieving such performance requires balancing
competing desirable features, including a high particle number, isolation of
atoms from collisions, insensitivity to motional effects, and high duty-cycle
operation. Here we demonstrate a new platform based on arrays of ultracold
strontium atoms confined within optical tweezers that realizes a novel
combination of these features by providing a scalable platform for isolated
atoms that can be interrogated multiple times. With this tweezer-array clock,
we achieve greater than 3 second coherence times and record duty cycles up to
96%, as well as stability commensurate with leading platforms. By using optical
tweezer arrays --- a proven platform for the controlled creation of
entanglement through microscopic control --- this work further promises a new
path toward combining entanglement enhanced sensitivities with the most precise
optical clock transitions
Educational Demo Hyperboloid Hole in the Wall
ME450 Capstone Design and Manufacturing Experience: Fall 2015A hyperboloid of revolution demonstrates that a straight rod rotating about a central axis follows a curved path in three-dimensional space, forming a hyperboloid. This project aims to scale up a typical, tabletop hyperboloid of revolution demonstration to be life-size. The new demonstration, now six feet tall, will allow a child up to eight years of age to replace the rod. The mission of this project on a broader scale is to provide more mathematical background than traditionally available, with the hopes of getting younger generations interested in the STEM fields. As this demonstration would like to be used in classrooms and museums, the entire display will need to be easily assembled and transported.http://deepblue.lib.umich.edu/bitstream/2027.42/117344/1/ME450-F15-Project27-FinalReport.pd
Leveraging text data for causal inference using electronic health records
Text is a ubiquitous component of medical data, containing valuable
information about patient characteristics and care that are often missing from
structured chart data. Despite this richness, it is rarely used in clinical
research, owing partly to its complexity. Using a large database of patient
records and treatment histories accompanied by extensive notes by attendant
physicians and nurses, we show how text data can be used to support causal
inference with electronic health data in all stages, from conception and design
to analysis and interpretation, with minimal additional effort. We focus on
studies using matching for causal inference. We augment a classic matching
analysis by incorporating text in three ways: by using text to supplement a
multiple imputation procedure, we improve the fidelity of imputed values to
handle missing data; by incorporating text in the matching stage, we strengthen
the plausibility of the matching procedure; and by conditioning on text, we can
estimate easily interpretable text-based heterogeneous treatment effects that
may be stronger than those found across categories of structured covariates.
Using these techniques, we hope to expand the scope of secondary analysis of
clinical data to domains where quantitative data is of poor quality or
nonexistent, but where text is available, such as in developing countries
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Nanoscale Measurements of Charge Transfer at Cocatalyst/Semiconductor Interfaces in BiVO4 Particle Photocatalysts
Semiconductor photocatalyst particles convert solar energy to fuels like H2. The particles are often assumed to provide crystalline-facet-dependent electron-hole separation. A common strategy is to deposit a hydrogen evolution reaction (HER) electrocatalyst on electron-selective facets and an oxygen evolution reaction (OER) electrocatalyst on hole-selective facets. A precise understanding of how charge-carrier-selective contacts emerge and how they are rationally designed, however, is missing. Using a combination of ex situ and in situ conducting atomic force microscopy (AFM) experiments and new ionomer/catalyst-semiconductor test structures, we show how heterogeneity in charge-carrier selectivity can be measured at the nanoscale. We discover that the presence of the water/electrolyte interface is critical to induce hole selectivity between the CoOx water-oxidation catalyst and the BiVO4 light absorber. pH-dependent measurements suggest that negative surface charge on the semiconductor is central to inducing hole selectivity. The work also demonstrates a new approach to control local pH and introduce water using thin-film ionomers compatible with conductive AFM measurements
Reactivating Fetal Hemoglobin Expression in Human Adult Erythroblasts Through BCL11A Knockdown Using Targeted Endonucleases.
We examined the efficiency, specificity, and mutational signatures of zinc finger nucleases (ZFNs), transcriptional activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 systems designed to target the gene encoding the transcriptional repressor BCL11A, in human K562 cells and human CD34+ progenitor cells. ZFNs and TALENs were delivered as in vitro transcribed mRNA through electroporation; CRISPR/Cas9 was codelivered by Cas9 mRNA with plasmid-encoded guideRNA (gRNA) (pU6.g1) or in vitro transcribed gRNA (gR.1). Analyses of efficacy revealed that for these specific reagents and the delivery methods used, the ZFNs gave rise to more allelic disruption in the targeted locus compared to the TALENs and CRISPR/Cas9, which was associated with increased levels of fetal hemoglobin in erythroid cells produced in vitro from nuclease-treated CD34+ cells. Genome-wide analysis to evaluate the specificity of the nucleases revealed high specificity of this specific ZFN to the target site, while specific TALENs and CRISPRs evaluated showed off-target cleavage activity. ZFN gene-edited CD34+ cells had the capacity to engraft in NOD-PrkdcSCID-IL2Rγnull mice, while retaining multi-lineage potential, in contrast to TALEN gene-edited CD34+ cells. CRISPR engraftment levels mirrored the increased relative plasmid-mediated toxicity of pU6.g1/Cas9 in hematopoietic stem/progenitor cells (HSPCs), highlighting the value for the further improvements of CRISPR/Cas9 delivery in primary human HSPCs
The human ankyrin 1 promoter insulator sustains gene expression in a β-globin lentiviral vector in hematopoietic stem cells.
Lentiviral vectors designed for the treatment of the hemoglobinopathies require the inclusion of regulatory and strong enhancer elements to achieve sufficient expression of the β-globin transgene. Despite the inclusion of these elements, the efficacy of these vectors may be limited by transgene silencing due to the genomic environment surrounding the integration site. Barrier insulators can be used to give more consistent expression and resist silencing even with lower vector copies. Here, the barrier activity of an insulator element from the human ankyrin-1 gene was analyzed in a lentiviral vector carrying an antisickling human β-globin gene. Inclusion of a single copy of the Ankyrin insulator did not affect viral titer, and improved the consistency of expression from the vector in murine erythroleukemia cells. The presence of the Ankyrin insulator element did not change transgene expression in human hematopoietic cells in short-term erythroid culture or in vivo in primary murine transplants. However, analysis in secondary recipients showed that the lentiviral vector with the Ankyrin element preserved transgene expression, whereas expression from the vector lacking the Ankyrin insulator decreased in secondary recipients. These studies demonstrate that the Ankyrin insulator may improve long-term β-globin expression in hematopoietic stem cells for gene therapy of hemoglobinopathies
An atomic boson sampler
A boson sampler implements a restricted model of quantum computing. It is
defined by the ability to sample from the distribution resulting from the
interference of identical bosons propagating according to programmable,
non-interacting dynamics. Here, we demonstrate a new combination of tools for
implementing boson sampling using ultracold atoms in a two-dimensional,
tunnel-coupled optical lattice. These tools include fast and programmable
preparation of large ensembles of nearly identical bosonic atoms
( indistinguishability) by means of rearrangement with
optical tweezers and high-fidelity optical cooling, propagation for variable
evolution time in the lattice with low loss (, independent of
evolution time), and high fidelity detection of the atom positions after their
evolution (typically ). With this system, we study specific
instances of boson sampling involving up to atoms distributed among sites in the lattice. Direct verification of a given boson sampling
distribution is not feasible in this regime. Instead, we introduce and perform
targeted tests to determine the indistinguishability of the prepared atoms, to
characterize the applied family of single particle unitaries, and to observe
expected bunching features due to interference for a large range of atom
numbers. When extended to interacting systems, our work demonstrates the core
capabilities required to directly assemble ground and excited states in
simulations of various Hubbard models.Comment: 20 pages, 7 figures (main text and methods); 8 pages, 2 figures
(supplemental materials
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