99,717 research outputs found
Extreme recoils: impact on the detection of gravitational waves from massive black hole binaries
Recent numerical simulations of coalescences of highly spinning massive black
hole binaries (MBHBs) suggest that the remnant can suffer a recoil velocity of
the order of few thousands km/s. We study here, by means of dedicated
simulations of black holes build--up, how such extreme recoils could affect the
cosmological coalescence rate of MBHBs, placing a robust lower limit for the
predicted number of gravitational wave (GW) sources detectable by future
space--borne missions (such as LISA). We consider two main routes for black
hole formation: one where seeds are light remnants of Population III stars
(~10^2 \msun), and one where seeds are much heavier (>~10^4 \msun), formed via
the direct gas collapse in primordial nuclear disks. We find that extreme
recoil velocities do not compromise the efficient MBHB detection by LISA. If
seeds are already massive and/or relatively rare, the detection rate is reduced
by only ~15%. The number of detections drops substantially (by ~60%) if seeds
are instead light and abundant, but in this case the number of predicted
coalescences is so high that at least ~10 sources in a three year observation
are guaranteed.Comment: 5 pages, 4 figures, replaced with final versio
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Amor y Apoyo: Lecciones de Latinx Families in Nourishing Resilience to First and Second-Generation College Students
The present qualitative study aims to understand how Latino/Hispanic herea er referred to as Latinx, parent involvement is different or similar among first- and second-generation college students in how they experience higher education and how parental education impacts the use of student support services. Hence, supporting Latinx student retention by developing university and parental relationships. Second-generation college students and Latinx parents were unable to be included in the study because of their scarcity or hesitation of participating. Therefore, participants included a convenience sample of six first-generation undergraduate students from a 4-year institution. Semi-structured interviews were conducted to obtain their stories of parental involvement and student involvement. Results suggest that (1) first-generation college students experience a hands-off involvement from parents, however, they enjoyed the freedom this brought, (2) Latinx parents might have a misunderstanding of college student identity, and (3) students expressed a desire to have their parents learn about and understand mental health. Implications of findings include universities creating more resources to support Latinx students’ mental health, as well as earlier school outreach for Latinx parent involvement to better inform them about the college lifestyle
Adaptive dynamic path re-planning RRT algorithms with game theory for UAVs
The main aim of this paper is to describe an adaptive re-planning algorithm based on a RRT and Game Theory to produce an efficient collision free obstacle adaptive Mission Path Planner for Search and Rescue (SAR) missions. This will provide UAV autopilots and flight computers with the capability to autonomously avoid static obstacles and No Fly Zones (NFZs) through dynamic adaptive path replanning. The methods and algorithms produce optimal collision free paths and can be integrated on a decision aid tool and UAV autopilots
N electrons in a quantum dot: Two-point Pade approximants
We present analytic estimates for the energy levels of N electrons (N = 2 -
5) in a two-dimensional parabolic quantum dot. A magnetic field is applied
perpendicularly to the confinement plane. The relevant scaled energy is shown
to be a smooth function of the parameter \beta=(effective Rydberg/effective dot
energy)^{1/6}. Two-point Pade approximants are obtained from the series
expansions of the energy near the oscillator () and Wigner
() limits. The approximants are expected to work with an error
not greater than 2.5% in the entire interval .Comment: 27 pages. LaTeX. 6 figures not include
Two and three electrons in a quantum dot: 1/|J| - expansion
We consider systems of two and three electrons in a two-dimensional parabolic
quantum dot. A magnetic field is applied perpendicularly to the electron plane
of motion. We show that the energy levels corresponding to states with high
angular momentum, J, and a low number of vibrational quanta may be
systematically computed as power series in 1/|J|. These states are relevant in
the high-B limit.Comment: LaTeX, 15 pages,6 postscript figure
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