Frequency responses of age-structured populations: Pacific salmon as an example

Increasing evidence of the effects of changing climate on physical ocean conditions and long-term changes in fish populations adds to the need to understand the effects of stochastic forcing on marine populations. Cohort resonance is of particular interest because it involves selective sensitivity to specific time scales of environmental variability, including that of mean age of reproduction, and, more importantly, very low frequencies (i.e., trends). We present an age-structured model for two Pacific salmon species with environmental variability in survival rate and in individual growth rate, hence spawning age distribution. We use computed frequency response curves and analysis of the linearized dynamics to obtain two main results. First, the frequency response of the population is affected by the life history stage at which variability affects the population; varying growth rate tends to excite periodic resonance in age structure, while varying survival tends to excite low-frequency fluctuation with more effect on total population size. Second, decreasing adult survival strengthens the cohort resonance effect at all frequencies, a finding that addresses the question of how fishing and climate change will interact.Comment: much revised: the version accepted by Theoretical Population Biolog

Sailing Down The Chesapeake Bay

People standing at river bank; Ship sailing on river; Trees on both sides of coverhttps://scholarsjunction.msstate.edu/cht-sheet-music/11246/thumbnail.jp

The incandescent rag

letters of the title glowing as if lit up by light bulbs.https://scholarsjunction.msstate.edu/cht-sheet-music/3970/thumbnail.jp

DNP Project: Knowledge and Attitudes Regarding Current Technology to Prevent Drug Diversion

The purpose of this project was to assess Student Registered Nurse Anesthetists (SRNA) and Certified Registered Nurse Anesthetists (CRNA) knowledge and attitudes about current interventions using technology to prevent drug diversion. A descriptive survey was sent to current Illinois Association of Nurse Anesthetists members that included SRNAs and CRNAs. The survey was a modified version of the Evidence-based nursing tool originally developed by Upton and Upton (2006) and was coded utilizing a Likert scale. Data were collected from a sample of 145 SRNAs and CRNAs. Knowledge regarding drug diversion was in the neutral range with a mean = 2.64 - 3.66 and SD = 0.85 - 1.24. Responses to attitudes regarding drug diversion were in the neutral range with a mean = 2.83 - 3.99 and SD = 0.83 - 1.35. Attitudes were more positive among females (m= 3.69, sd= 0.76) than males (m= 3.41, sd= 0.78). In addition, attitudes were more positive among those with Doctoral degrees (m= 3.86, sd= 0.56 than those with Master’s degrees (m= 3.48, sd= 0.81;t(83.447) = -3.141, p = .002). Analysis of the survey results found that overall, there were neutral opinions of knowledge and attitudes on drug diversion. Based on the overall neutrality of the results, revisions were made to the original survey. The revised survey was sent to five CRNAs to evaluate the tool for clarity and appropriateness of the survey items. Overall response supported that the revised survey tool may more accurately reflect survey participant knowledge and attitudes in regards to drug diversion. Recommendations for future research include utilization of the new survey tool with a goal of obtaining a larger response rate. Dependent on results, developing an educational tool in the future may help to improve knowledge and increase positive attitudes on the topic of drug diversion

Pride Of The Prairie

Photograph of Harry A. Ellis; Illustration of woman sitting on hill with black horse in backgroundhttps://scholarsjunction.msstate.edu/cht-sheet-music/7973/thumbnail.jp

Silv\u27ry Bells : Jingle Bells

https://digitalcommons.library.umaine.edu/mmb-ps/3036/thumbnail.jp

Hyacinth Rag

Two hyacinth plantshttps://scholarsjunction.msstate.edu/cht-sheet-music/13783/thumbnail.jp

Letter to Sonora Dodd from Mary Botsford Charlton, May 21, 1915

Letter to Sonora Dodd from Mary Botsford Charlton, Managing Editor, The People\u27s Home Journal, New York.https://digitalcommons.whitworth.edu/fathers-day-correspondence/1029/thumbnail.jp