Spatial Ecology of the Desert Tortoise: Sampling Frequency and Biological Influences

Understanding the spatial ecology of an animal is crucial for making positive efforts to provide for its recovery. As a part of this understanding, home range estimates are used to answer a variety of questions in ecological studies. However, home range estimates based on a collection of radio-telemetry locations are sensitive to methodological variables, such as sample size, sampling frequency, and the choice of estimator. Further confounding these estimates are a number of physical, social, and ecological factors. Identifying the main determinants of space use patterns by a species may aid conservation efforts. The Desert Tortoise (Gopherus agassizii)of the Mojave Desert inhabits an extreme environment where a number of factors likely influence its land use patterns. Prior home range estimates of the Desert Tortoise are wide ranging from different portions of the desert, due in part to the use of a variety of sampling methodologies. My goal was to determine how different facets of sampling methodology affect home range estimates of the Desert Tortoise using two widely-used home range estimators, the minimum convex polygon and the fixed kernel density estimator. In addition, investigated physical, social, and ecological variables to examine the dominant factor(s) influencing the spatial ecology of the Desert Tortoise. Results suggested that previous home range estimates were highly influenced by the sampling regime utilized. Home range estimates in this study were much greater than those in the literature, possibly due to an intensive sampling regime. This suggests that tortoises may require more land than previously thought. Males and females demonstrated very different patterns of space and burrow use, suggesting these variables affect estimates for each sex differently. I conclude that a combination of these variables determines space use in tortoises. By adopting a uniform sampling methodology, researchers can better provide comparable data across studies in a holistic effort to understand the spatial ecology of a species

Minimum Nurse Staffing Legislation and the Financial Performance of California Hospitals

To estimate the effect of minimum nurse staffing ratios on California acute care hospitals’ financial performance

The Effect of Minimum Nurse Staffing Legislation on Uncompensated Care Provided by California Hospitals

This study assesses whether California’s minimum nurse staffing legislation affected the amount of uncompensated care provided by California hospitals. Using data from California’s Office of Statewide Health Planning and Development, the American Hospital Association Annual Survey and InterStudy, we divide hospitals into quartiles based on pre-regulation staffing levels. Controlling for other factors, we estimate changes in the growth rate of uncompensated care in the three lowest staffing quartiles relative to the quartile of hospitals with the highest staffing level. Our sample includes short-term general hospitals over the period 1999 to 2006. We find that growth rates in uncompensated care are lower in the first three staffing quartiles as compared to the highest quartile; however, results are statistically significant only for county and for-profit hospitals in quartiles one and three. We conclude that minimum nurse staffing ratios may lead some hospitals to limit uncompensated care, likely due to increased financial pressure

California's Minimum Nurse Staffing Legislation: Results from a Natural Experiment

To determine whether, following implementation of California's minimum nurse staffing legislation, changes in acuity-adjusted nurse staffing and quality of care in California hospitals outpaced similar changes in hospitals in comparison states without such regulations

Author Correction: FAM222A encodes a protein which accumulates in plaques in Alzheimer’s disease (Nature Communications, (2020), 11, 1, (411), 10.1038/s41467-019-13962-0)

In the original version of the manuscript, the image shown in Figure 4g, bottom row (Aβ1–42 + rAggregatin), under “6h” was incorrect. This image incorrectly showed the same sample as shown in the original Figure 4g, top row (Aβ1–42), under “0.5h”. The correct version of figure 4g is as follows: (Figure presented.) which replaces the previous incorrect version: (Figure presented.)

Toward a Consensus on Guiding Principles for Health Systems Strengthening

Based upon a review of the literature, Robert Chad Swanson and colleagues present a set of guiding principles for health systems strengthening

Ras activation of Erk restores impaired tonic BCR signaling and rescues immature B cell differentiation

B cell receptors (BCRs) generate tonic signals critical for B cell survival and early B cell development. To determine whether these signals also mediate the development of transitional and mature B cells, we examined B cell development using a mouse strain in which nonautoreactive immunoglobulin heavy and light chain–targeted B cells express low surface BCR levels. We found that reduced BCR expression translated into diminished tonic BCR signals that strongly impaired the development of transitional and mature B cells. Constitutive expression of Bcl-2 did not rescue the differentiation of BCR-low B cells, suggesting that this defect was not related to decreased cell survival. In contrast, activation of the Ras pathway rescued the differentiation of BCR-low immature B cells both in vitro and in vivo, whereas extracellular signal-regulated kinase (Erk) inhibition impaired the differentiation of normal immature B cells. These results strongly suggest that tonic BCR signaling mediates the differentiation of immature into transitional and mature B cells via activation of Erk, likely through a pathway requiring Ras