295 research outputs found
Achromatizing a liquid-crystal spectropolarimeter: Retardance vs Stokes-based calibration of HiVIS
Astronomical spectropolarimeters can be subject to many sources of systematic
error which limit the precision and accuracy of the instrument. We present a
calibration method for observing high-resolution polarized spectra using
chromatic liquid-crystal variable retarders (LCVRs). These LCVRs allow for
polarimetric modulation of the incident light without any moving optics at
frequencies >10Hz. We demonstrate a calibration method using pure Stokes input
states that enables an achromatization of the system. This Stokes-based
deprojection method reproduces input polarization even though highly chromatic
instrument effects exist. This process is first demonstrated in a laboratory
spectropolarimeter where we characterize the LCVRs and show example
deprojections. The process is then implemented the a newly upgraded HiVIS
spectropolarimeter on the 3.67m AEOS telescope. The HiVIS spectropolarimeter
has also been expanded to include broad-band full-Stokes spectropolarimetry
using achromatic wave-plates in addition to the tunable full-Stokes
polarimetric mode using LCVRs. These two new polarimetric modes in combination
with a new polarimetric calibration unit provide a much more sensitive
polarimetric package with greatly reduced systematic error.Comment: Accepted in PAS
Substance use and academic success: Results from three longitudinal panels, including analyses of adjustments for panel attrition
https://deepblue.lib.umich.edu/bitstream/2027.42/137861/1/occ62.pd
Education-drug use relationships: An examination of racial/ethnic subgroups
https://deepblue.lib.umich.edu/bitstream/2027.42/137857/1/occ66.pd
HealthâRelated Quality of Life in Kidney Donors From the Last Five Decades: Results From the RELIVE Study
Live donation benefits recipients, but the longâterm consequences for donors remain uncertain. Renal and Lung Living Donors Evaluation Study surveyed kidney donors (Nâ=â2455; 61% women; mean age 58, aged 24â94; mean time from donation 17 years, range 5â48 years) using the Short Formâ36 Health Survey (SFâ36). The 95% confidence intervals for White and AfricanâAmerican donors included or exceeded SFâ36 norms. Over 80% of donors reported average or above average health for their age and sex (pâ1 SD below norm). Obesity, history of psychiatric difficulties and nonâWhite race were risk factors for impaired physical health; history of psychiatric difficulties was a risk factor for impaired mental health. Education, older donation age and a firstâdegree relation to the recipient were protective factors. One percent reported that donation affected their health very negatively. Enhanced predonation evaluation and counseling may be warranted, along with ongoing monitoring for overweight donors. Questionnaires completed by 2544 living donors 5 to 48 years postnephrectomy show that 80% have average or better healthârelated quality of life for their age and sex based on SFâ36 norms and that obesity, history of psychiatric difficulties and nonwhite race are risk factors for poor healthârelated quality of life outcomes, whereas being older, having more education and/or being a firstâdegree relation to the recipient predict better outcomes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/100300/1/ajt12434.pd
Emotional WellâBeing of Living Kidney Donors: Findings From the RELIVE Study
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109345/1/ajt12906.pd
Metal-coordination: using one of nature's tricks to control soft material mechanics
Growing evidence supports a critical role of dynamic metal-coordination crosslinking in soft biological material properties such as self-healing and underwater adhesion. Using bio-inspired metal-coordinating polymers, initial efforts to mimic these properties have shown promise. Here we demonstrate how bio-inspired aqueous polymer network mechanics can be easily controlled via metal-coordination crosslink dynamics; metal ion-based crosslink stability control allows aqueous polymer network relaxation times to be finely tuned over several orders of magnitude. In addition to further biological material insights, our demonstration of this compositional scaling mechanism should provide inspiration for new polymer material property-control designs.National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (DMR-0820054)Danish Council for Independent Research (Natural Sciences for a Post-Doctoral Fellowship 272-08-0087)University of Chicago. Materials Research Science and Engineering Center (DMR 0820054
Signaling in Secret: Pay-for-Performance and the Incentive and Sorting Effects of Pay Secrecy
Key Findings: Pay secrecy adversely impacts individual task performance because it weakens the perception that an increase in performance will be accompanied by increase in pay; Pay secrecy is associated with a decrease in employee performance and retention in pay-for-performance systems, which measure performance using relative (i.e., peer-ranked) criteria rather than an absolute scale (see Figure 2 on page 5); High performing employees tend to be most sensitive to negative pay-for- performance perceptions; There are many signals embedded within HR policies and practices, which can influence employeesâ perception of workplace uncertainty/inequity and impact their performance and turnover intentions; and When pay transparency is impractical, organizations may benefit from introducing partial pay openness to mitigate these effects on employee performance and retention
Catechol Polymers for pH-Responsive, Targeted Drug Delivery to Cancer Cells
A novel cell-targeting, pH-sensitive polymeric carrier was employed in this study for delivery of the anticancer drug bortezomib (BTZ) to cancer cells. Our strategy is based on facile conjugation of BTZ to catechol-containing polymeric carriers that are designed to be taken up selectively by cancer cells through cell surface receptor-mediated mechanisms. The polymer used as a building block in this study was poly(ethylene glycol), which was chosen for its ability to reduce nonspecific interactions with proteins and cells. The catechol moiety was exploited for its ability to bind and release borate-containing therapeutics such as BTZ in a pH-dependent manner. In acidic environments, such as in cancer tissue or the subcellular endosome, BTZ dissociates from the polymer-bound catechol groups to liberate the free drug, which inhibits proteasome function. A cancer-cell-targeting ligand, biotin, was presented on the polymer carriers to facilitate targeted entry of drug-loaded polymer carriers into cancer cells. Our study demonstrated that the cancer-targeting drug-polymer conjugates dramatically enhanced cellular uptake, proteasome inhibition, and cytotoxicity toward breast carcinoma cells in comparison with nontargeting drug-polymer conjugates. The pH-sensitive catechol-boronate binding mechanism provides a chemoselective approach for controlling the release of BTZ in targeted cancer cells, establishing a concept that may be applied in the future toward other boronic acid-containing therapeutics to treat a broad range of diseases
Enzymatically Degradable Mussel-Inspired Adhesive Hydrogel
Mussel-inspired adhesive hydrogels represent innovative candidate medical sealants or glues. In the present work, we describe an enzyme-degradable mussel-inspired adhesive hydrogel formulation, achieved by incorporating minimal elastase substrate peptide Ala-Ala into the branched poly(ethylene glycol) (PEG) macromonomer structure. The system takes advantage of neutrophil elastase expression upregulation and secretion from neutrophils upon recruitment to wounded or inflamed tissue. By integrating adhesive degradation behaviors that respond to cellular cues, we expand the functional range of our mussel-inspired adhesive hydrogel platforms. Rapid (<1 min) and simultaneous gelation and adhesion of the proteolytically active, catechol-terminated precursor macromonomer was achieved by addition of sodium periodate oxidant. Rheological analysis and equilibrium swelling studies demonstrated that the hydrogel is appropriate for soft tissue-contacting applications. Notably, hydrogel storage modulus (G) achieved values on the order of 10 kPa, and strain at failure exceeded 200% strain. Lap shear testing confirmed the materials adhesive behavior (shear strength: 30.4 ± 3.39 kPa). Although adhesive hydrogel degradation was not observed during short-term (27 h) in vitro treatment with neutrophil elastase, in vivo degradation proceeded over several months following dorsal subcutaneous implantation in mice. This work represents the first example of an enzymatically degradable mussel-inspired adhesive and expands the potential biomedical applications of this family of materials
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