Desigm and Development Considerations of a Learning Object Repository

A learning objects repository (LOR) is a web-based educational portal that houses, displays, and delivers sharable content objects for educational purposes. Design of such a repository encounters a number of considerations that relate the behavior of the information system to the content objects it manages. This paper examines these design issues in light of standards we have utilized. In particular, the instructional design of our learning objects is based on a concept called progressive scaffolding, which refers to the process of providing differing levels of media guidance. A brief description of related research is included. Furthermore, our objects are compliant with the Advanced Distributed Learning’s Sharable Content Object Reference Model (SCORM) to ensure they behave in a uniform and predictable manner. This paper also reviews existing content portals and gives a summary of an evaluation project carried out with a prototype

Healthcare utilization and spending by children with cancer on Medicaid

BackgroundChildren with cancer are a unique patient population with high resource, complex healthcare needs. Understanding their healthcare utilization could highlight areas for care optimization.ProcedureWe performed a retrospective, cross‐sectional analysis of the 2014 Truven Marketscan Medicaid Database to explore clinical attributes, utilization, and spending among children with cancer who were Medicaid enrollees. Eligible patients included children (ages 0–18 years) with cancer (Clinical Risk Group 8). Healthcare utilization and spending (per member per month, PMPM) were assessed overall and across specific healthcare services.ResultsChildren with cancer (n = 5,405) represent less than 1% of the 1,516,457 children with medical complexity in the dataset. Children with cancer had high services use: laboratory/radiographic testing (93.0%), outpatient specialty care (83.4%), outpatient therapy/treatment (53.4%), emergency department (43.7%), hospitalization (31.5%), home healthcare (9.5%). PMPM spending for children with cancer was $3,706 overall and$2,323 for hospital care.ConclusionChildren with cancer have high healthcare resource use and spending. Differences in geographic distribution of services for children with cancer and the trajectory of spending over the course of therapy are areas for future investigation aimed at lowering costs of care without compromising on health outcomes.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138316/1/pbc26569_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138316/2/pbc26569.pd

Reflux related hospital admissions after fundoplication in children with neurological impairment: retrospective cohort study

Objective To examine the impact of fundoplication on reflux related hospital admissions for children with neurological impairment

On the Spectral Evolution of Cool, Helium-Atmosphere White Dwarfs: Detailed Spectroscopic and Photometric Analysis of DZ Stars

We present a detailed analysis of a large spectroscopic and photometric sample of DZ white dwarfs based on our latest model atmosphere calculations. We revise the atmospheric parameters of the trigonometric parallax sample of Bergeron, Leggett, & Ruiz (12 stars) and analyze 147 new DZ white dwarfs discovered in the Sloan Digital Sky Survey. The inclusion of metals and hydrogen in our model atmosphere calculations leads to different atmospheric parameters than those derived from pure helium models. Calcium abundances are found in the range from log (Ca/He) = -12 to -8. We also find that fits of the coolest objects show peculiarities, suggesting that our physical models may not correctly describe the conditions of high atmospheric pressure encountered in the coolest DZ stars. We find that the mean mass of the 11 DZ stars with trigonometric parallaxes, = 0.63 Mo, is significantly lower than that obtained from pure helium models, = 0.78 Mo, and in much better agreement with the mean mass of other types of white dwarfs. We determine hydrogen abundances for 27% of the DZ stars in our sample, while only upper limits are obtained for objects with low signal-to-noise ratio spectroscopic data. We confirm with a high level of confidence that the accretion rate of hydrogen is at least two orders of magnitude smaller than that of metals (and up to five in some cases) to be compatible with the observations. We find a correlation between the hydrogen abundance and the effective temperature, suggesting for the first time empirical evidence of a lower temperature boundary for the hydrogen screening mechanism. Finally, we speculate on the possibility that the DZA white dwarfs could be the result of the convective mixing of thin hydrogen-rich atmospheres with the underlying helium convection zone.Comment: 67 pages, 32 figures, accepted for publication in Ap

A classification of the effective metric in nonlinear electrodynamics

We show that only two types of effective metrics are possible in certain nonlinear electromagnetic theories. This is achieved by using the dependence of the effective metric on the energy-momentum tensor of the background along with the Segr\`e classification of the latter. Each of these forms is completely determined by single scalar function, which characterizes the light cone of the nonlinear theory. We compare this light cone with that of Minkowski in two examples.Comment: Accepted for publication in Classical & Quantum Gravit

The Spitzer Extragalactic Representative Volume Survey (SERVS): The Environments of High-z SDSS Quasi-Stellar-Objects

This paper presents a study of the environments of SDSS Quasi-Stellar-Objects (QSOs) in the Spitzer Extragalactic Representative Volume Survey (SERVS). We concentrate on the high-redshift QSOs as these have not been studied in large numbers with data of this depth before. We use the IRAC 3.6-4.5{\mu}m colour of objects and ancillary r-band data to filter out as much foreground contamination as possible. This technique allows us to find a significant (> 4-{\sigma}) over-density of galaxies around QSOs in a redshift bin centred on z ~ 2.0 and a (> 2-{\sigma}) over-density of galaxies around QSOs in a redshift bin centred on z ~ 3.3. We compare our findings to the predictions of a semi-analytic galaxy formation model, based on the {\Lambda}CDM millennium simulation, and find for both redshift bins that the model predictions match well the source-density we have measured from the SERVS data.Comment: 13 pages, 12 figures, Accepted by Ap

Acute Pancreatitis in the Emergency Department

Introduction: Acute pancreatitis (AP) is a common emergency department (ED) presentation with a variety of outcomes. Stratifying AP severity with scoring systems can allow physicians to effectively manage patient disposition. Objective: To identify ED pancreatitis patients who will likely be admitted to the ICU or be discharged within 48 hours, and to validate existing pancreatitis severity scores. Methods: Patients with a final ED diagnosis of AP and/or lipase ≥ 3 times the upper limit of normal were enrolled in a prospective, observational chart review study. Parametric and non-parametric descriptive statistics were used to describe the patient population. Area under receiver operating curve (AUC) was used to determine the predictive accuracy of existing pancreatitis scores. Results: Ranson criteria, Glasgow-Imrie (GI) criteria, Bedside Index of Severity in Acute Pancreatitis (BISAP), and Harmless Acute Pancreatitis Score (HAPS) were assessed. GI criteria (AUC = 0.77) had the highest predictive accuracy for ICU admission, while Ranson criteria (AUC = 0.62) had the highest predictive accuracy for early discharge. Mean scores of ICU patients were significantly (p \u3c 0.05) higher than those of non-ICU patients in all four scoring systems; however, mean scores in ICU patients failed to meet the severe case threshold for all four scoring systems. Discussion: Existing pancreatitis scoring systems cannot consistently predict AP severity in ED patients. The small difference in mean ICU and non-ICU patient scores illustrates the difficulty of using scoring systems to stratify AP severity in the ED. Further efforts to develop an ED-specific scoring system could allow physicians to more efficiently admit patients

The environments of z~1 Active Galactic Nuclei at 3.6um

We present an analysis of a large sample of AGN environments at z~1 using stacked Spitzer data at 3.6um. The sample contains type-1 and type-2 AGN in the form of quasars and radio galaxies, and spans a large range in both optical and radio luminosity. We find, on average, that 2 to 3 massive galaxies containing a substantial evolved stellar population lie within a 200-300 kpc radius of the AGN, constituting a >8-sigma excess relative to the field. Secondly, we find evidence for the environmental source density to increase with the radio luminosity of AGN, but not with black-hole mass. This is shown first by dividing the AGN into their classical AGN types, where we see more significant over-densities in the fields of the radio-loud AGN. If instead we dispense with the classical AGN definitions, we find that the source over-density as a function of radio luminosity for all our AGN exhibits a positive correlation. One interpretation of this result is that the Mpc-scale environment is in some way influencing the radio emission that we observe from AGN. This could be explained by the confinement of radio jets in dense environments leading to enhanced radio emission or, alternatively, may be linked to more rapid black-hole spin brought on by galaxy mergers.Comment: 13 pages, 12 figures, accepted by MNRA

Magnetic Tower Outflows from a Radial Wire Array Z-pinch

We present the first results of high energy density laboratory astrophysics experiments which explore the evolution of collimated outflows and jets driven by a toroidal magnetic field. The experiments are scalable to astrophysical flows in that critical dimensionless numbers such as the Mach number, the plasma beta and the magnetic Reynolds number are all in the astrophysically appropriate ranges. Our experiments use the MAGPIE pulsed power machine and allow us to explore the role of magnetic pressure in creating and collimating the outflow as well as showing the creation of a central jet within the broader outflow cavity. We show that currents flow along this jet and we observe its collimation to be enhanced by the additional hoop stresses associated with the generated toroidal field. Although at later times the jet column is observed to go unstable, the jet retains its collimation. We also present simulations of the magnetic jet evolution using our two-dimensional resistive magneto-hydrodynamic (MHD) laboratory code. We conclude with a discussion of the astrophysical relevance of the experiments and of the stability properties of the jet.Comment: Accepted by MNRAS. 17 pages without figures. Full version with figures can be found at http://www.pas.rochester.edu/~afrank/labastro/MF230rv.pd