Parameterizing probabilities for estimating age-composition distributions for mixture models

When estimating parameters that constitute a discrete probability distribution {pj}, it is difficult to determine how constraints should be made to guarantee that the estimated parameters { pˆj} constitute a probability distribution (i.e., pˆj>0, Σ pˆj =1). For age distributions estimated from mixtures of length-at-age distributions, the EM (expectationmaximization) algorithm (Hasselblad, 1966; Hoenig and Heisey, 1987; Kimura and Chikuni, 1987), restricted least squares (Clark, 1981), and weak quasisolutions (Troynikov, 2004) have all been used. Each of these methods appears to guarantee that the estimated distribution will be a true probability distribution with all categories greater than or equal to zero and with individual probabilities that sum to one. In addition, all these methods appear to provide a theoretical basis for solutions that will be either maximum-likelihood estimates or at least convergent to a probability distribu

Community Engagement in the International Emergency Response to Ebola, 2014-2016

An unsafe and illegal burial conducted in Port Loko, Sierra Leone during the Ebola epidemic of 2014-2016 exposed competing risk perspectives between emergency responders and the affected community, and called into question community engagement (CE) efforts in the response – particularly regarding strict, but culturally-problematic burial protocols. This work interrogates the effectiveness of CE through development of a novel, two-dimensional metric. The first dimension builds on the work of Davidson (1998) and others to parse CE efforts into four distinct domains: Information Provision, Consultation, Participation, and Community Empowerment. The second dimension builds on the work of Arnstein (1969) and others to create a semi-quantitative scale which assigns an Empowerment Score from zero to two, assessing the degree to which community feedback leads to material changes in interventions in each domain. The Empowerment Score methodology was applied to analyze CE efforts reported in literature and in the CE standards of international response organizations. The methodology was then used in a modified Delphi survey of responders and anthropologists with experience in the Ebola response in Sierra Leone, to characterize the successes and shortcomings of CE efforts, with a focus on burial of persons who had died of Ebola. Quantitative analysis of Delphi panelists’ numeric scores, combined with qualitative analysis of their textual comments, revealed substantial disagreement between diverse experts regarding the appropriateness or success of CE efforts in the response. However, there was general agreement among the experts that future epidemic responses should take into account cultural concerns in the negotiation of burial protocols or other interventions that may collide with cultural values. For future emergency responses, the incorporation of social scientists such as anthropologists into CE structures, as well as intentional involvement of community members in the planning and implementation of disease-control measures, is recommended. Additionally, the international emergency response community is called to a posture of humility, acknowledging that realities other than the medicalized and materialistic drive human behavior, including health-affecting behavior. Respectful engagement with risk as understood by a community, combined with a Harm Reduction philosophy to define interventions, may save more lives than biomedically pure, but coercive approaches

Bose-Einstein Condensate Comagnetometer

We describe a comagnetometer employing the $f=1$ and $f=2$ ground state hyperfine manifolds of a $^{87}$Rb spinor Bose-Einstein condensate as co-located magnetometers. The hyperfine manifolds feature nearly opposite gyromagnetic ratios and thus the sum of their precession angles is only weakly coupled to external magnetic fields, while being highly sensitive to any effect that rotates both manifolds in the same way. The $f=1$ and $f=2$ transverse magnetizations and azimuth angles are independently measured by non-destructive Faraday rotation probing, and we demonstrate a $44.0(8)\text{dB}$ common-mode rejection in good agreement with theory. We show how spin-dependent interactions can be used to inhibit $2\rightarrow 1$ hyperfine relaxing collisions, extending to $\sim 1\text{s}$ the transverse spin lifetime of the $f=1,2$ mixtures. The technique could be used in high sensitivity searches for new physics on sub-millimeter length scales, precision studies of ultra-cold collision physics, and angle-resolved studies of quantum spin dynamics