Nonnormality and the localized control of extended systems

The idea of controlling the dynamics of spatially extended systems using a small number of localized perturbations is very appealing - such a setup is easy to implement in practice. However, when the distance between controllers generating the perturbations becomes large, control fails due to increasing sensitivity of the system to noise and nonlinearities. We show that this failure is due to the fact that the evolution operator for the controlled system becomes increasingly nonnormal as the distance between controllers grows. This nonnormality is the result of control and can arise even for systems whose evolution operator is normal in the absence of control.Comment: 4 pages, 4 figure

The black-hole masses of Seyfert galaxies and quasars

The central black-hole masses of a sample of 30 luminous quasars are estimated using H-beta FWHM measurements from a combination of new and previously-published nuclear spectra. The quasar black-hole mass estimates are combined with reverberation-mapping measurements for a sample of Seyfert galaxies (Wandel 1999) in order to study AGN black-hole masses over a wide range in nuclear luminosity. It is found that black-hole mass and bulge luminosity are well correlated and follow a relation consistent with that expected if black-hole and bulge mass are directly proportional. Contrary to the results of Wandel (1999) no evidence is found that Seyfert galaxies follow a different Mblack-Mbulge relation to quasars. However, the black-hole mass distributions of the radio-loud and radio-quiet quasar sub-samples are found to be significantly different, with the median black-hole mass of the radio-loud quasars a factor of three larger than their radio-quiet counterparts. Finally, utilizing the elliptical galaxy fundamental plane to provide stellar velocity dispersion estimates, a comparison is performed between the virial H-beta black-hole mass estimates and those of the Mblack-sigma correlations of Gebhardt et al. (2000a) and Merritt & Ferrarese (2000). With the disc-like geometry of the broad-line region adopted in this paper, the virial H-beta black-hole masses indicate that the correct normalization of the black-hole vs. bulge mass relation is Mblack=0.0025Mbulge, while the standard assumption of purely random broad-line velocities leads to Mblack=0.0008Mbulge. The normalization of Mblack=0.0025Mbulge provided by the disc model is in remarkably good agreement with that inferred for our quasar sample using the (completely independent) Mblack-sigma correlations.Comment: 10 pages, 6 figures, accepted for publication in MNRA

An updated systematic review of the cost-effectiveness of therapies for metastatic breast cancer

Purpose: The goal of this systematic review is to provide an update to the review by Pouwels et al. by conducting a systematic review and an assessment of the reporting quality of the economic analyses conducted since 2014. Methods: This systematic review identified published articles focused on metastatic breast cancer treatment using the Medline/PubMed and Scopus databases and the following search criteria: (((cost effectiveness[MeSH Terms]) OR (cost effectiveness) OR (cost-effectiveness) OR (cost utility) OR (cost–utility) OR (economic evaluation)) AND ((“metastatic breast cancer”) OR (“advanced breast cancer”))). The reporting quality of the included articles was evaluated using the International Society of Pharmacoeconomics and Outcomes Research (ISPOR) Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist. Results: Of the 256 identified articles, 67 of the articles were published after October 2014 when the prior systematic review stopped its assessment (Pouwels et al. in Breast Cancer Res Treat 165:485–498, 2017). From the 67 articles, we narrowed down to include 17 original health economic analyses specific to metastatic or advanced breast cancer. These articles were diverse with respect to methods employed and interventions included. Conclusion: Although each of the articles contributed their own analytic strengths and limitations, the overall quality of the studies was moderate. The review demonstrated that the vast majority of the reported incremental cost-effectiveness ratios exceeded the typically employed willingness to pay thresholds used in each country of analysis. Only three of the reviewed articles studied chemotherapies rather than treatments targeting either HER2 or hormone receptors, demonstrating a gap in the literature

Concurrent prescribing of opioids with other sedating medications after cancer diagnosis: a population-level analysis

Purpose: Cancer is a major reason for concurrent prescription of opioids with other sedating medications—particularly benzodiazepines and gabapentinoids—yet population-based assessments of the extent and predictors of concurrent prescribing among clinically and demographically diverse patients with cancer are lacking. Methods: We conducted a retrospective cohort study of patients with non-metastatic cancer using North Carolina cancer registry data linked with Medicare and private insurance claims (2013–2016). We used modified Poisson regression to assess associations of patient characteristic with adjusted relative risk (aRR) of new concurrent prescribing of opioids with benzodiazepines or gabapentinoids after diagnosis. Results: Overall, 15% of patients were concurrently prescribed opioids with benzodiazepines or gabapentinoids. Characteristics independently associated with an increased risk of concurrent prescribing included cancer type (e.g., aRR cervical vs. colorectal cancer: 1.55, 95% CI: 1.12–2.14); prior use of opioids (aRR: 2.43, 95% CI:2.21–2.67), benzodiazepines (aRR: 4.08, 95% CI: 3.72–4.48), or gabapentinoids (3.82, 95% CI: 3.31–4.39), and premorbid mental health conditions, including substance use disorder (aRR: 1.27, 95% CI: 1.05–1.54). Black and Hispanic patients were less likely to experience concurrent prescribing (aRR, Black vs. White: 0.35, 95% CI: 0.15–0.83; aRR, Hispanic vs. White: 0.75, 95% CI: 0.66–0.85). Conclusion: Approximately 1 in 7 patients with cancer was concurrently prescribed opioids with other sedating medications. Associations between patient characteristics and risk of concurrent prescribing highlight predictors of concurrent prescribing and suggest a rationale for systematic assessment of substance use history at diagnosis. Future research could explore inequitable pain and symptom management and investigate risk of adverse medication-related events

Methicillin-resistant Staphylococcus aureus in Horses and Horse Personnel, 2000–2002

Methicillin-resistant Staphylococcus aureus was isolated from horses and horse personnel in a pattern suggestive of interspecies transmission of a human-origin clone