Time filter

Source Type

Northfield, MN, United States

Carleton College is a private non-sectarian, coeducational, liberal arts college in Northfield, Minnesota. The college enrolls 2,035 undergraduate students, and employs 220 full-time faculty members. In its 2014 edition of college rankings, U.S. News & World Report ranked Carleton College the seventh-best liberal arts college in the United States and ranked Carleton number one for undergraduate teaching at a national liberal arts college. Wikipedia.

Egge E.S.,Carleton College
European Journal of Combinatorics

We first give a combinatorial interpretation of Everitt, Littlejohn, and Wellman's Legendre-Stirling numbers of the first kind. We then give a combinatorial interpretation of the coefficients of the polynomial analogous to that of the Eulerian numbers, where are Everitt, Littlejohn, and Wellman's Legendre-Stirling numbers of the second kind. Finally we use a result of Bender to show that the limiting distribution of these coefficients as n approaches infinity is the normal distribution. © 2010 Elsevier Ltd. Source

Weisberg J.M.,Carleton College | Nice D.J.,Lafayette College | Taylor J.H.,Princeton University
Astrophysical Journal

We present results of more than three decades of timing measurements of the first known binary pulsar, PSR B1913+16. Like most other pulsars, its rotational behavior over such long timescales is significantly affected by small-scale irregularities not explicitly accounted for in a deterministic model. Nevertheless, the physically important astrometric, spin, and orbital parameters are well determined and well decoupled from the timing noise. We have determined a significant result for proper motion, μα = - 1.43 ±0.13,μδ =-0.70 ±0.13 mas yr-1. The pulsar exhibited a small timing glitch in 2003 May, with Δf/f = 3.7 × 10-11, and a smaller timing peculiarity in mid-1992. A relativistic solution for orbital parameters yields improved mass estimates for the pulsar and its companion, m1 = 1.4398 ± 0.0002 M⊙ and m2 = 1.3886 ± 0.0002 M⊙. The system's orbital period has been decreasing at a rate 0.997 ± 0.002 times that predicted as a result of gravitational radiation damping in general relativity. As we have shown before, this result provides conclusive evidence for the existence of gravitational radiation as predicted by Einstein's theory. © 2010. The American Astronomical Society. Source

Tasson J.D.,Carleton College
Physical Review D - Particles, Fields, Gravitation and Cosmology

A largely unconstrained set of relativity-violating effects is studied via the gravitomagnetic effect on intrinsic spins. The results of existing comagnetometer experiments are used to place constraints on two new combinations of these effects at the 10% level. We show that planned improvements in these experiments will make them competitive with the best existing sensitivities to this elusive class of relativity-violating effects. Prospects for measuring the conventional general-relativistic gravitomagnetic effect are also considered. © 2012 American Physical Society. Source

Coughlin M.W.,Carleton College
Classical and Quantum Gravity

The LIGO and Virgo detectors are sensitive to a variety of noise sources, such as instrumental artifacts and environmental disturbances. The Stochastic Transient Analysis Multi-detector Pipeline has been developed to search for long-duration (t 1 s) gravitational-wave (GW) signals. This pipeline can also be used to identify environmental noise transients. Here, we present an algorithm to determine when long-duration noise sources couple into the interferometers, as well as identify what these noise sources are. We analyze the cross-power between a GW strain channel and an environmental sensor, using pattern recognition tools to identify statistically significant structure in cross-power timefrequency maps. We identify interferometer noise from airplanes, helicopters, thunderstorms and other sources. Examples from LIGOs sixth science run, S6, and Virgos third scientific run, VSR3, are presented. © 2011 IOP Publishing Ltd. Source

Whited M.T.,Carleton College
Beilstein Journal of Organic Chemistry

The concept of frustrated Lewis pairs (FLPs) has received considerable attention of late, and numerous reports have demonstrated the power of non- or weakly interacting Lewis acid-base pairs for the cooperative activation of small molecules. Although most studies have focused on the use of organic or main-group FLPs that utilize steric encumbrance to prevent adduct formation, a related strategy can be envisioned for both organic and inorganic complexes, in which "electronic frustration" engenders reactivity consistent with both nucleophilic (basic) and electrophilic (acidic) character. Here we propose that such a description is consistent with the behavior of many coordinatively unsaturated transition-metal species featuring metal-ligand multiple bonds, and we further demonstrate that the resultant reactivity may be a powerful tool for the functionalization of C-H and E-H bonds. © 2012 Whited; licensee Beilstein-Institut. Source

Discover hidden collaborations