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12 results on '"English, Samuel"'

1. Updated Constraints on Asteroid-Mass Primordial Black Holes as Dark Matter

Author

Smyth, Nolan, Profumo, Stefano, English, Samuel, Jeltema, Tesla, McKinnon, Kevin, and Guhathakurta, Puragra

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics, High Energy Physics - Theory
Abstract

Microlensing of stars places significant constraints on sub-planetary-mass compact objects, including primordial black holes, as dark matter candidates. As the lens' Einstein radius in the source plane becomes comparable to the size of the light source, however, source amplification is strongly suppressed, making it challenging to constrain lenses with a mass at or below $10^{-10}$ solar masses, i.e. asteroid-mass objects. Current constraints, using Subaru HSC observations of M31, assume a fixed source size of one solar radius. Here we point out that the actual stars in M31 bright enough to be used for microlensing are typically much larger. We correct the HSC constraints by constructing a source size distribution based on the M31 PHAT survey and on a synthetic stellar catalogue, and by correspondingly weighing the finite-size source effects. We find that the actual HSC constraints are weaker by up to almost three orders of magnitude in some cases, broadening the range of masses for which primordial black holes can be the totality of the cosmological dark matter by almost one order of magnitude., Comment: 8 pages, 6 figures, accepted to PRD. Moved supplemental section into main body

Published
2019
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2. Updated constraints on asteroid-mass primordial black holes as dark matter

Author

Smyth, Nolan, Profumo, Stefano, English, Samuel, Jeltema, Tesla, McKinnon, Kevin, and Guhathakurta, Puragra

Subjects
Space Sciences, Astronomical Sciences, Physical Sciences, astro-ph.CO, hep-th, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract

Microlensing of stars places significant constraints on sub-planetary-masscompact objects, including primordial black holes, as dark matter candidates.As the lens' Einstein radius in the source plane becomes comparable to the sizeof the light source, however, source amplification is strongly suppressed,making it challenging to constrain lenses with a mass at or below $10^{-10}$solar masses, i.e. asteroid-mass objects. Current constraints, using Subaru HSCobservations of M31, assume a fixed source size of one solar radius. Here wepoint out that the actual stars in M31 bright enough to be used formicrolensing are typically much larger. We correct the HSC constraints byconstructing a source size distribution based on the M31 PHAT survey and on asynthetic stellar catalogue, and by correspondingly weighing the finite-sizesource effects. We find that the actual HSC constraints are weaker by up toalmost three orders of magnitude in some cases, broadening the range of massesfor which primordial black holes can be the totality of the cosmological darkmatter by almost one order of magnitude.

Published
2020

4. Exploring the Scientific Literature Specific to Surfing Equipment and Design: A Scoping Review

Author

Romanin, Alexander, English, Samuel, Kemp-Smith, Kevin, Furness, James, and Newcomer, Sean

Subjects
Engineering Physics, Medical Sciences, Physiology, Physics, Fin, Wetsuit, Sports Sciences, Fluid Dynamics, Musculoskeletal, Neural, and Ocular Physiology, FOS: Biological sciences, Physical Sciences and Mathematics, Medicine and Health Sciences, Equipment design, Surfing, Physiological Processes, Surfboard
Abstract

A scoping review which aims to identify and explore scientific literature pertaining to surfing equipment design. This review looks to identify themes and knowledge gaps within the sport of surfing.

Published
2022
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5. 'Education of Urban, Unenrolled, and Mobile Indians.' A Position Paper.

Author

English, Samuel F.

Abstract

The problem of an American Indian not on a tribal roll is that he is not a legal ward of any particular tribe and is therefore ineligible for financial aid for educational purposes. The relocation program has moved Indians from reservations to urgan areas to encourage assimilation, further adding to the identity problem. Urban Indians are pressuring relocation centers for advanced educational opportunities, but resources are limited for higher education. Often Indian students are not provided with enough funds to complete a program they are encouraged to begin. Little information is available on the problems of urban Indians. Existing organizations such as the National Indian Youth Council should be contracted with to research Indian problems in all urban areas with large concentrations of Indian people. An Indian organization such as the United Scholarship Service should be contracted with to conduct an investigation of existing educational programs for Indian students to result in compilation and dissemination of information about opportunities for higher education. (JH)

Published
1970

8. Cytochrome c(sub)3 mutants of Desulfovibrio desulfuricans

Author

Rapp-Giles, Barbara J., Casalot, Laurence, English, Samuel R., Ringbauer, Joseph A. Jr, Dolla, Alain, and Wall, Judy D.

Subjects
Cytochrome c -- Genetic aspects, Gene mutations -- Analysis, Sulfur bacteria -- Physiological aspects, Electron transport -- Physiological aspects, Biological sciences
Abstract

Results show that the tetraheme cytochrome c(sub)3 plays a role in the electron transport pathway in Desulfovibrio desulfuricans bacteria.

Published
2000

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