390 research outputs found
Understanding the Use of Curriculum Materials: A Cross-Site Research Study Report
A cross-site study conducted under the auspices of CSMC was designed to explore curriculum enactment of a particular mathematical topic in the three districts. District representatives selected âcomposing and decomposingâ as the focus of the study, noting that it was an area of mathematics that teachers find challenging to teach and that students find challenging to learn.
The hope was that the study would both inform the participating districts, and provide a model for others in the field to use in studying the implementation of particular mathematical ideas of interest.This paper was supported by funds from the National Science Foundation (NSF)
Lipid ratios as a marker for red blood cell storage quality and as a possible explanation for donor gender differences in storage quality
Background and objectives
Red blood cells that are stored for transfusions as red cell concentrates (RCCs) undergo changes during the storage period, culminating in the lysis of the cells. The goal of this work is to find markers that are linked to high haemolysis, in order to explain the interâdonor variability that is known to occur in storage quality, and also the known differences between RCCs from male and female donors.
Materials and methods
The relative amounts of lipids at the end of the storage period were compared for one group of low haemolysis samples (24 units, all â€0·15% haemolysis), and one group of high haemolysis samples (26 units, all â„0·5% haemolysis). Representative lipids were analysed from different lipid classes, including cholesterol, phosphatidylcholine, phosphatidylethanolamine, sphingomyelin and ceramide. Whole membrane preparations were analysed with one mass spectrometry technique, and lipid extracts were analysed with a second mass spectrometry technique.
Results
The ratio of palmitoylâoleoyl phosphatidylcholine (POPC) to sphingomyelin was different for the high and low haemolysis groups (P = 0·0001) and for the RCCs from male and female donors (P = 0·0009). The ratio of cholesterol to phospholipids showed only minimal links to haemolysis. Higher relative amounts of sphingomyelin were associated with lower haemolysis, and higher relative amounts of ceramides were associated with increased haemolysis.
Conclusion
The level of sphingomyelinase activity and the resulting ratio of sphingomyelin to POPC is proposed as a possible marker for RCC storage quality
Hemolysis Pathways during Storage of Erythrocytes and Inter-Donor Variability in Erythrocyte Morphology
Visual Orbits of Spectroscopic Binaries with the CHARA Array. III. HD 8374 and HD 24546
We present the visual orbits of two long period spectroscopic binary stars,
HD 8374 and HD 24546, using interferometric observations acquired with the
CHARA Array and the Palomar Testbed Interferometer. We also obtained new radial
velocities from echelle spectra using the APO 3.5 m and Fairborn 2.0 m
telescopes. By combining the visual and spectroscopic observations, we solve
for the full, three-dimensional orbits and determine the stellar masses and
distances to within 3% uncertainty. We then estimate the effective temperature
and radius of each component star through Doppler tomography and spectral
energy distribution analyses, in order to compare the observed stellar
parameters to the predictions of stellar evolution models. For HD 8374, we find
masses of M1 = 1.636 +/- 0.050 Msun and M2 = 1.587 +/- 0.049 Msun, radii of R1
= 1.84 +/- 0.05 Rsun and R2 = 1.66 +/- 0.12 Rsun, temperatures of Teff1 = 7280
+/- 110 K and Teff2 = 7280 +/- 120 K, and an estimated age of 1.0 Gyr. For HD
24546, we find masses of M1 = 1.434 +/- 0.014 Msun and M2 = 1.409 +/- 0.014
Msun, radii of R1 = 1.67 +/- 0.06 Rsun and R2 = 1.60 +/- 0.10 Rsun,
temperatures of Teff1 = 6790 +/- 120 K and Teff2 = 6770 +/- 90 K, and an
estimated age of 1.4 Gyr. HD 24546 is therefore too old to be a member of the
Hyades cluster, despite its physical proximity to the group.Comment: 18 pages, 10 figures. Accepted for publication in A
Spectroscopy, MOST Photometry, and Interferometry of MWC 314: Is it an LBV or an interacting binary?
MWC 314 is a bright candidate luminous blue variable that resides in a fairly
close binary system, with an orbital period of 60.7530.003 d. We observed
MWC 314 with a combination of optical spectroscopy, broad-band ground- and
space-based photometry, as well as with long baseline, near-infrared
interferometry. We have revised the single-lined spectroscopic orbit and
explored the photometric variability. The orbital light curve displays two
minima each orbit that can be partially explained in terms of the tidal
distortion of the primary that occurs around the time of periastron. The
emission lines in the system are often double-peaked and stationary in their
kinematics, indicative of a circumbinary disc. We find that the stellar wind or
circumbinary disc is partially resolved in the K\prime-band with the longest
baselines of the CHARA Array. From this analysis, we provide a simple,
qualitative model in an attempt to explain the observations. From the
assumption of Roche Lobe overflow and tidal synchronisation at periastron, we
estimate the component masses to be M1 M and M2
M, which indicates a mass of the LBV that is extremely low. In addition
to the orbital modulation, we discovered two pulsational modes with the MOST
satellite. These modes are easily supported by a low-mass hydrogen-poor star,
but cannot be easily supported by a star with the parameters of an LBV. The
combination of these results provides evidence that the primary star was likely
never a normal LBV, but rather is the product of binary interactions. As such,
this system presents opportunities for studying mass-transfer and binary
evolution with many observational techniques.Comment: 26 pages, 7 figures, 5 tables, 2 appendices with 7 additional tables
and 2 additional figures. Accepted for publication in MNRA
Evaluation Research and Institutional Pressures: Challenges in Public-Nonprofit Contracting
This article examines the connection between program evaluation research and decision-making by public managers. Drawing on neo-institutional theory, a framework is presented for diagnosing the pressures and conditions that lead alternatively toward or away the rational use of evaluation research. Three cases of public-nonprofit contracting for the delivery of major programs are presented to clarify the way coercive, mimetic, and normative pressures interfere with a sound connection being made between research and implementation. The article concludes by considering how public managers can respond to the isomorphic pressures in their environment that make it hard to act on data relating to program performance.This publication is Hauser Center Working Paper No. 23. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers
Pulmonary Hypertension and Other Potentially Fatal Pulmonary Complications in Systemic Juvenile Idiopathic Arthritis
Objective Systemic juvenile idiopathic arthritis (JIA) is characterized by fevers, rash, and arthritis, for which interleukinâ1 (ILâ1) and ILâ6 inhibitors appear to be effective treatments. Pulmonary arterial hypertension (PAH), interstitial lung disease (ILD), and alveolar proteinosis (AP) have recently been reported with increased frequency in systemic JIA patients. Our aim was to characterize and compare systemic JIA patients with these complications to a larger cohort of systemic JIA patients. Methods Systemic JIA patients who developed PAH, ILD, and/or AP were identified through an electronic Listserv and their demographic, systemic JIA, and pulmonary disease characteristics as well as their medication exposure information were collected. Patients with these features were compared to a cohort of systemic JIA patients enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) registry. Results The patients (n = 25) were significantly ( P < 0.05) more likely than the CARRA registry cohort (n = 389) to be female; have more systemic features; and have been exposed to an ILâ1 inhibitor, tocilizumab, corticosteroids, intravenous immunoglobulin, cyclosporine, and cyclophosphamide. Twenty patients (80%) were diagnosed with pulmonary disease after 2004. Twenty patients (80%) had macrophage activation syndrome (MAS) during their disease course and 15 patients (60%) had MAS at pulmonary diagnosis. Sixteen patients had PAH, 5 had AP, and 7 had ILD. Seventeen patients (68%) were taking or recently discontinued (<1 month) a biologic agent at pulmonary symptom onset; 12 patients (48%) were taking antiâILâ1 therapy (primarily anakinra). Seventeen patients (68%) died at a mean of 10.2 months from the diagnosis of pulmonary complications. Conclusion PAH, AP, and ILD are underrecognized complications of systemic JIA that are frequently fatal. These complications may be the result of severe uncontrolled systemic disease activity and may be influenced by medication exposure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97453/1/21889_ftp.pd
Recommended from our members
An integrative view of the regulatory and transcriptional landscapes in mouse hematopoiesis.
Thousands of epigenomic data sets have been generated in the past decade, but it is difficult for researchers to effectively use all the data relevant to their projects. Systematic integrative analysis can help meet this need, and the VISION project was established for validated systematic integration of epigenomic data in hematopoiesis. Here, we systematically integrated extensive data recording epigenetic features and transcriptomes from many sources, including individual laboratories and consortia, to produce a comprehensive view of the regulatory landscape of differentiating hematopoietic cell types in mouse. By using IDEAS as our integrative and discriminative epigenome annotation system, we identified and assigned epigenetic states simultaneously along chromosomes and across cell types, precisely and comprehensively. Combining nuclease accessibility and epigenetic states produced a set of more than 200,000 candidate cis-regulatory elements (cCREs) that efficiently capture enhancers and promoters. The transitions in epigenetic states of these cCREs across cell types provided insights into mechanisms of regulation, including decreases in numbers of active cCREs during differentiation of most lineages, transitions from poised to active or inactive states, and shifts in nuclease accessibility of CTCF-bound elements. Regression modeling of epigenetic states at cCREs and gene expression produced a versatile resource to improve selection of cCREs potentially regulating target genes. These resources are available from our VISION website to aid research in genomics and hematopoiesis.National Institute of Diabetes and Digestive and Kidney Diseases (grant number R24DK106766-01A1), the National Human Genome Research Institute (grant number U54HG006998
Arctic soil methane sink increases with drier conditions and higher ecosystem respiration
Arctic wetlands are known methane (CH4) emitters but recent studies suggest that the Arctic CH4 sink strength may be underestimated. Here we explore the capacity of well-drained Arctic soils to consume atmospheric CH4 using >40,000 hourly flux observations and spatially distributed flux measurements from 4 sites and 14 surface types. While consumption of atmospheric CH4 occurred at all sites at rates of 0.092 ± 0.011 mgCH4 mâ2 hâ1 (mean ± s.e.), CH4 uptake displayed distinct diel and seasonal patterns reflecting ecosystem respiration. Combining in situ flux data with laboratory investigations and a machine learning approach, we find biotic drivers to be highly important. Soil moisture outweighed temperature as an abiotic control and higher CH4 uptake was linked to increased availability of labile carbon. Our findings imply that soil drying and enhanced nutrient supply will promote CH4 uptake by Arctic soils, providing a negative feedback to global climate change
- âŠ