7 research outputs found
Brownian motion of solitons in a Bose-Einstein Condensate
We observed and controlled the Brownian motion of solitons. We launched solitonic excitations in highly elongated 87 Rb Bose-Einstein condensates (BECs) and showed that a dilute background of impurity atoms in a different internal state dramatically affects the soliton. With no impurities and in one-dimension (1D), these solitons would have an infinite lifetime, a consequence of integrability. In our experiment, the added impurities scatter off the much larger soliton, contributing to its Brownian motion and decreasing its lifetime. We describe the soliton\u27s diffusive behavior using a quasi-1D scattering theory of impurity atoms interacting with a soliton, giving diffusion coefficients consistent with experiment
Sexual harassment reported by undergraduate female physicists
Sexual harassment occurs more frequently in male-dominated fields and physics is a more male-dominated field than most other science, technology, engineering, and mathematics (STEM) fields. Thus, it is important to examine the occurrence and impact of sexual harassment on women in physics. A survey of undergraduate women, who attended a conference for undergraduate women in physics, revealed that approximately three quarters (74.3%; 338/455) of survey respondents experienced at least one type of sexual harassment. This sample was recruited from a large fraction of undergraduate women in physics in the United States. We find that certain types of sexual harassment predict a negative sense of belonging and exacerbate the imposter phenomenon. The types of sexual harassment that predict these outcomes, both forms of gender harassment, while seemingly less severe types of harassment, have been found to have substantially negative personal and professional consequences. These findings are important since prior work has found that sense of belonging and the imposter phenomenon are related to students’ persistence in STEM fields. Our results have implications for understanding and improving persistence in physics by informing the community about the occurrence of sexual harassment and its effects so that we can begin to work towards reducing its occurrence and mitigating its effects
Coronal Heating as Determined by the Solar Flare Frequency Distribution Obtained by Aggregating Case Studies
Flare frequency distributions represent a key approach to addressing one of
the largest problems in solar and stellar physics: determining the mechanism
that counter-intuitively heats coronae to temperatures that are orders of
magnitude hotter than the corresponding photospheres. It is widely accepted
that the magnetic field is responsible for the heating, but there are two
competing mechanisms that could explain it: nanoflares or Alfv\'en waves. To
date, neither can be directly observed. Nanoflares are, by definition,
extremely small, but their aggregate energy release could represent a
substantial heating mechanism, presuming they are sufficiently abundant. One
way to test this presumption is via the flare frequency distribution, which
describes how often flares of various energies occur. If the slope of the power
law fitting the flare frequency distribution is above a critical threshold,
as established in prior literature, then there should be a
sufficient abundance of nanoflares to explain coronal heating. We performed
600 case studies of solar flares, made possible by an unprecedented number
of data analysts via three semesters of an undergraduate physics laboratory
course. This allowed us to include two crucial, but nontrivial, analysis
methods: pre-flare baseline subtraction and computation of the flare energy,
which requires determining flare start and stop times. We aggregated the
results of these analyses into a statistical study to determine that . This is below the critical threshold, suggesting that Alfv\'en
waves are an important driver of coronal heating.Comment: 1,002 authors, 14 pages, 4 figures, 3 tables, published by The
Astrophysical Journal on 2023-05-09, volume 948, page 7