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1. Perspectives on a peer-driven intervention to promote pre-exposure prophylaxis (PrEP) uptake among men who have sex with men in southern New England: a qualitative study

Author

Jun Tao, Hannah Parent, Ishu Karki, Harrison Martin, Sarah Alexandra Marshall, Jhanavi Kapadia, Amy S. Nunn, Brandon D. L. Marshall, Henry F. Raymond, Leandro Mena, and Philip A. Chan

Subjects
Peer-driven intervention, Men who have sex with men (MSM), HIV pre-exposure prophylaxis (PrEP), Black/African American, Hispanic/Latino, Public aspects of medicine, RA1-1270
Abstract

Abstract Background Pre-exposure prophylaxis (PrEP) is a highly effective pharmaceutical intervention that prevents HIV infection, but PrEP uptake across the US has been slow among men who have sex with men (MSM), especially among Black/African American (B/AA) and Hispanic /Latino (H/L) MSM. This study investigates the acceptability and essential components of a peer-driven intervention (PDI) for promoting PrEP uptake among MSM, with a specific focus on B/AA and H/L communities. Methods We conducted 28 semi-structured, qualitative interviews with MSM in southern New England to explore the components of a PDI, including attitudes, content, and effective communication methods. A purposive sampling strategy was used to recruit diverse participants who reflect the communities with the highest burden of HIV infection. Results Of 28 study participants, the median age was 28 years (interquartile range [IQR]: 25, 35). The sample comprised B/AA (39%, n = 11) and H/L (50%, n = 14) individuals. Notably, nearly half of the participants (46%) were current PrEP users. We found that many participants were in favor of using a PDI approach for promoting PrEP. Additionally, several participants showed interest in becoming peer educators themselves. They emphasized the need for strong communication skills to effectively teach others about PrEP. Moreover, participants noted that peer education should cover key topics like how PrEP works, how effective it is, and any possible side effects. Conclusions Our study shows that effective PDIs, facilitated by well-trained peers knowledgeable about PrEP, could enhance PrEP uptake among MSM, addressing health disparities and potentially reducing HIV transmission in B/AA and H/L communities.

Published
2024
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4. Spectrahedra and Convex Hulls of Rank-One Elements

Author

Harrison, Martin Ames

Subjects
Mathematics - Optimization and Control, Mathematics - Algebraic Geometry
Abstract

The Helton-Nie Conjecture (HNC) is the proposition that every convex semialgebraic set is a spectrahedral shadow. Here we prove that HNC is equivalent to another propo- sition related to quadratically constrained quadratic programming. Namely, that the convex hull of the rank-one elements of any spectrahedron is a spectrahedral shadow. In the case of compact convex semialgebraic sets, the spectrahedra may be taken to be compact. We illustrate the relationship between spetrahedra and these convex subsets with examples., Comment: 11 pages, 2 images

Published
2015

7. Pfister's theorem fails in the free case

Author

Harrison, Martin

Subjects
Mathematics - Rings and Algebras
Abstract

Artin solved Hilbert's $17^{th}$ problem by showing that every positive semidefinite polynomial can be realized as a sum of squares of rational functions. Pfister gave a bound on the number of squares of rational functions: if $p$ is a positive semi-definite polynomial in $n$ variables, then there is a polynomial $q$ so that $q^2p$ is a sum of at most $2^n$ squares. As shown by D'Angelo and Lebl, the analog of Pfister's theorem fails in the case of Hermitian polynomials. Specifically, it was shown that the rank of any multiple of the polynomial $\|z\|^{2d} \equiv (\sum_j |z_j|^2)^d$ is bounded below by a quantity depending on $d$. Here we prove that a similar result holds in a free $\ast$-algebra.

Published
2011

9. Six poems

Author

Harrison, Martin

Published
1976

45. Using game theory to model interspecific brood parasitism in bird populations

Author

Harrison, Martin D.

Subjects
519, QA Mathematics, QH0301 Biology, QL Zoology
Abstract

The interaction between hosts and parasites in bird populations has been studied extensively. I use game theoretic methods to model this interaction. This has been done previously but has not been studied taking into account the detailed sequential nature of this game. I introduce models allowing the host and parasite to make a number of decisions which will depend on a number of natural factors. A sequence of events follows, which is broken down into two key stages; firstly the interaction between the host and the parasite adult, and secondly that between the host and the parasite chick. The final decision involves the host choosing whether to raise or abandon the chicks that are in the nest. There are certain natural parameters and probabilities which are central to these various decisions; in particular the host is generally uncertain whether parasitism has taken place, but can assess the likelihood of parasitism based upon certain cues (e.g. how many eggs remain in its nest). I have taken elements of games which have been previously created and constructed my own models to fully describe this interaction. These parasites have different methods of parasitizing the nests of their hosts, and the hosts can in turn have different reactions to these parasites. This is later built into a model where there is more than one host nesting over a breeding season. We have a number of nesting sites and different time points in which the host can begin to nest. In the previous models the host was given the opportunity to abandon the nest. In this game the host is allowed to abandon and then restart the nesting process. The probability that the host is parasitized can be decided using a number of factors including the number of hosts laying during a given time period, the nesting site or the number of parasites during the course of the season. Using these models we are able to find situations which match those which we have seen in nature. Also the models are able to predict what natural changes such as parasitism rate or mimicry will do to the interaction. Overall I believe these models to give as good an indication of the key elements of the interaction and how they can change over time.

Published
2010

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