2,412 research outputs found
Moving Ahead Amid Fiscal Challenges: A Look at Medicaid Spending, Coverage and Policy Trends
Examines fiscal year 2011 trends in state efforts to control Medicaid spending, reform payment and delivery systems, and prepare for healthcare reform implementation, as well as projections in spending and enrollment growth for fiscal year 2012
Exploring practical estimates of the ensemble size necessary for particle filters
Author Posting. © American Meteorological Society, 2015. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Monthly Weather Review 144 (2016): 861-875, doi:10.1175/MWR-D-14-00303.1.Particle filtering methods for data assimilation may suffer from the âcurse of dimensionality,â where the required ensemble size grows rapidly as the dimension increases. It would, therefore, be useful to know a priori whether a particle filter is feasible to implement in a given system. Previous work provides an asymptotic relation between the necessary ensemble size and an exponential function of , a statistic that depends on observation-space quantities and that is related to the system dimension when the number of observations is large; for linear, Gaussian systems, the statistic can be computed from eigenvalues of an appropriately normalized covariance matrix. Tests with a low-dimensional system show that these asymptotic results remain useful when the system is nonlinear, with either the standard or optimal proposal implementation of the particle filter. This study explores approximations to the covariance matrices that facilitate computation in high-dimensional systems, as well as different methods to estimate the accumulated system noise covariance for the optimal proposal. Since may be approximated using an ensemble from a simpler data assimilation scheme, such as the ensemble Kalman filter, the asymptotic relations thus allow an estimate of the ensemble size required for a particle filter before its implementation. Finally, the improved performance of particle filters with the optimal proposal, relative to those using the standard proposal, in the same low-dimensional system is demonstrated.Slivinski was supported by the NSF through Grants DMS-0907904 and DMS-1148284, by ONR through DOD (MURI) Grant N000141110087, and by NCARâs Advanced Study Program during a collaborative visit to NCAR.2016-05-1
Differences in Antibiotic Resistance in Fresh-water Bacteria from Furman Lake and Feeder Streams
A one page summary by three Furman students describing their research on bacteria found in the Furman Lake.https://scholarexchange.furman.edu/lake-documents/1007/thumbnail.jp
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Less-structured time in children's daily lives predicts self-directed executive functioning.
Executive functions (EFs) in childhood predict important life outcomes. Thus, there is great interest in attempts to improve EFs early in life. Many interventions are led by trained adults, including structured training activities in the lab, and less-structured activities implemented in schools. Such programs have yielded gains in children's externally-driven executive functioning, where they are instructed on what goal-directed actions to carry out and when. However, it is less clear how children's experiences relate to their development of self-directed executive functioning, where they must determine on their own what goal-directed actions to carry out and when. We hypothesized that time spent in less-structured activities would give children opportunities to practice self-directed executive functioning, and lead to benefits. To investigate this possibility, we collected information from parents about their 6-7 year-old children's daily, annual, and typical schedules. We categorized children's activities as "structured" or "less-structured" based on categorization schemes from prior studies on child leisure time use. We assessed children's self-directed executive functioning using a well-established verbal fluency task, in which children generate members of a category and can decide on their own when to switch from one subcategory to another. The more time that children spent in less-structured activities, the better their self-directed executive functioning. The opposite was true of structured activities, which predicted poorer self-directed executive functioning. These relationships were robust (holding across increasingly strict classifications of structured and less-structured time) and specific (time use did not predict externally-driven executive functioning). We discuss implications, caveats, and ways in which potential interpretations can be distinguished in future work, to advance an understanding of this fundamental aspect of growing up
Do Smoothing Activities Indicate Higher or Lower Financial Reporting Quality? Evidence from Effective Tax Rates
Prior literature is mixed as to whether smoothing through accruals indicates higher or lower financial reporting quality (Tucker and Zarowin 2006; Jayaraman 2008; Dechow et al. 2010). Motivated by the unique inter-temporal features and reporting incentives of tax expense, we provide new evidence on this debate by examining the link between smoothing of GAAP effective tax rates (ETRs) and the likelihood of financial restatements. Different from earnings smoothingâs insignificant relation with restatements, we find that ETR smoothing through tax accruals is associated with a lower likelihood of financial restatement and lower likelihood of tax-related financial reporting fraud. Further investigation reveals that such negative associations are stronger in firms with a higher level of discretion in tax reporting and when the demand and monitoring for transparent reporting is higher. We also document corroborating evidence that smoothing through tax accruals increases the informativeness of GAAP ETRs for predicting future cash ETRs. Collectively, our results contribute to the financial reporting and tax literatures by providing evidence that smoothing activities pertaining to tax accruals are consistent with higher financial reporting quality
Atf6alpha impacts cell number by influencing survival, death and proliferation
BACKGROUND: A growing body of literature suggests the cell-intrinsic activity of Atf6alpha during ER stress responses has implications for tissue cell number during growth and development, as well as in adult biology and tumorigenesis [1]. This concept is important, linking the cellular processes of secretory protein synthesis and endoplasmic reticulum stress response with functional tissue capacity and organ size. However, the field contains conflicting observations, especially notable in secretory cell types like the pancreatic beta cell.
SCOPE OF REVIEW: Here we summarize current knowledge of the basic biology of Atf6alpha, along with the pleiotropic roles Atf6alpha plays in cell life and death decisions and possible explanations for conflicting observations. We include studies investigating the roles of Atf6alpha in cell survival, death and proliferation using well-controlled methodology and specific validated outcome measures, with a focus on endocrine and metabolic tissues when information was available.
MAJOR CONCLUSIONS: The net outcome of Atf6alpha on cell survival and cell death depends on cell type and growth conditions, the presence and degree of ER stress, and the duration and intensity of Atf6alpha activation. It is unquestioned that Atf6alpha activity influences the cell fate decision between survival and death, although opposite directions of this outcome are reported in different contexts. Atf6alpha can also trigger cell cycle activity to expand tissue cell number through proliferation. Much work remains to be done to clarify the many gaps in understanding in this important emerging field
Recoiling black holes: prospects for detection and implications of spin alignment
Supermassive black hole (BH) mergers produce powerful gravitational wave (GW)
emission. Asymmetry in this emission imparts a recoil kick to the merged BH,
which can eject the BH from its host galaxy altogether. Recoiling BHs could be
observed as offset active galactic nuclei (AGN). Several candidates have been
identified, but systematic searches have been hampered by large uncertainties
regarding their observability. By extracting merging BHs and host galaxy
properties from the Illustris cosmological simulations, we have developed a
comprehensive model for recoiling AGN. Here, for the first time, we model the
effects of BH spin alignment and recoil dynamics based on the gas-richness of
host galaxies. We predict that if BH spins are not highly aligned,
seeing-limited observations could resolve offset AGN, making them promising
targets for all-sky surveys. For randomly-oriented spins, less than about 10
spatially-offset AGN may be detectable in HST-COSMOS, and > 10^3 could be found
with Pan-STARRS, LSST, Euclid, and WFIRST. Nearly a thousand velocity-offset
AGN are predicted within the SDSS footprint; the rarity of large broad-line
offsets among SDSS quasars is likely due in part to selection effects but
suggests that spin alignment plays a role in suppressing recoils. Nonetheless,
in our most physically motivated model where alignment occurs only in gas-rich
mergers, hundreds of offset AGN should be found in all-sky surveys. Our
findings strongly motivate a dedicated search for recoiling AGN.Comment: 30 pages, 19 figures. Accepted to MNRAS after minor revision
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