Peregrine Falcon Eggs: Egg Size, Hatchling Sex, and Clutch Sex Ratios

Eggs (n = 367) collected from wild Peregrine Falcon (Falco peregrinus anatum) nests between 1976 and 1990 in Colorado and New Mexico were artificially incubated and hatched. We retrospectively examined these data for variation in egg length, breadth, and initial mass of hatchlings to resolve questions about relationships among egg size, chick size, and sex; and egg size related to first and second clutches and years. Egg length and breadth were significantly related to chick mass at hatching. Neither egg size nor hatchling mass were related to sex. Egg breadth slightly increased and then decreased over the years eggs were collected, which possibly reflects a re-established and then aging wild falcon population or other environmental variation. We also evaluated clutch sex ratios relative to theory based on sexual size dimorphism and local resource competition. Sex ratios did not significantly differ from 1:1 within first or second clutches separately or when combined. Thus, Peregrine Falcons in this population apparently did not skew clutch sex ratios in accordance with local resource competition or Fisherian theory

HIV risk perception and sexual behavior among HIV-uninfected men and transgender women who have sex with men in sub-Saharan Africa: Findings from the HPTN 075 qualitative sub-study.

There remains a limited understanding of how men who have sex with men (MSM) and transgender women (TGW) in sub-Saharan Africa (SSA) perceive their risk for HIV and how risk influences behavior during sexual interactions. We performed thematic analysis on in-depth interviews from the qualitative sub-study of HPTN 075 in Kenya, Malawi, and South Africa. Using the Integrated Behavioral Model (IBM) constructs, we found that most MSM and TGW perceived themselves to be at risk for HIV, leading them to regularly engage in safer sexual behaviors. Notably, even though these MSM and TGW perceived themselves to be at risk for HIV, some of them reported engaging in transactional sex, sex under the influence of alcohol, and intentional non-use of condoms. This indicates that HIV risk perception was not always associated with safer sexual behaviors or a reduction in risk behaviors. Attitudes (negative attitudes toward condom use), perceived norms (social pressures), and environment constraints (contextual barriers) were related to MSM and TGW not engaging in safe sexual behavior. Hearing the perspectives of MSM and TGW on their sexual behavior continues to be important for the development and implementation of effective prevention policies and interventions. Eliminating structural barriers such as stigma, discrimination, and criminalization of same-sex sexuality is a crucial prerequisite for the success of interventions to promote sexual health among MSM and TGW in SSA

Optimizing over trained GNNs via symmetry breaking

Optimization over trained machine learning models has applications including: verification, minimizing neural acquisition functions, and integrating a trained surrogate into a larger decision-making problem. This paper formulates and solves optimization problems constrained by trained graph neural networks (GNNs). To circumvent the symmetry issue caused by graph isomorphism, we propose two types of symmetry-breaking constraints: one indexing a node 0 and one indexing the remaining nodes by lexicographically ordering their neighbor sets. To guarantee that adding these constraints will not remove all symmetric solutions, we construct a graph indexing algorithm and prove that the resulting graph indexing satisfies the proposed symmetry-breaking constraints. For the classical GNN architectures considered in this paper, optimizing over a GNN with a fixed graph is equivalent to optimizing over a dense neural network. Thus, we study the case where the input graph is not fixed, implying that each edge is a decision variable, and develop two mixed-integer optimization formulations. To test our symmetry-breaking strategies and optimization formulations, we consider an application in molecular design.Comment: 10 main pages, 27 with appendix, 9 figures, 7 table