Boston College

About: Boston College is a education organization based out in Boston, Massachusetts, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 9749 authors who have published 25406 publications receiving 1105145 citations. The organization is also known as: BC.

A Short, Rigid, Structurally Pure Carbon Nanotube by Stepwise Chemical Synthesis

Abstract: The inaccessibility of uniform-diameter, single-chirality carbon nanotubes (CNTs) in pure form continues to thwart efforts by scientists to use these ultrathin materials in innovative applications that could revolutionize nanoscale electronics. Stimulated by the challenge to address this long-standing problem, we and other organic chemists have envisioned a new production strategy involving the controlled elongation of small hydrocarbon templates, such as hemispherical nanotube end-caps, prepared by bottom-up chemical synthesis; the diameter and rim structure encoded in the template would dictate the diameter and chirality of the resulting CNT. Toward that objective, a short [5,5] CNT has now been synthesized by stepwise chemical methods. This C50H10 geodesic polyarene has been isolated, purified, crystallized, and fully characterized by NMR spectroscopy, UV–vis absorption spectroscopy, high resolution mass spectrometry, and X-ray crystallography.

Ab initio thermal transport in compound semiconductors

Abstract: We use a recently developed ab initio approach to calculate the lattice thermal conductivities of compound semiconductors. An exact numerical solution of the phonon Boltzmann transport equation is implemented, which uses harmonic and anharmonic interatomic force constants determined from density functional theory as inputs. We discuss the method for calculating the anharmonic interatomic force constants in some detail, and we describe their role in providing accurate thermal conductivities in a range of systems. This first-principles approach obtains good agreement with experimental results for well-characterized systems (Si, Ge, and GaAs). We determine the intrinsic upper bound to the thermal conductivities of cubic aluminum-V, gallium-V, and indium-V compounds as limited by anharmonic phonon scattering. The effects of phonon-isotope scattering on the thermal conductivities are examined in these materials and compared to available experimental data. We also obtain the lattice thermal conductivities of other technologically important materials, AlN and SiC. For most materials, good agreement with the experimental lattice thermal conductivities for naturally occurring isotopic compositions is found. We show that the overall frequency scale of the acoustic phonons and the size of the gap between acoustic and optic phonons play important roles in determining the lattice thermal conductivity of each system. The first-principles approach used here can provide quantitative predictions of thermal transport in a wide range of systems.

Leadership competencies for implementing planned organizational change

Abstract: This paper bridges the leadership and organizational change literatures by exploring the relationship between managers' leadership competencies (namely, their effectiveness at person-oriented and task-oriented behaviors) and the likelihood that they will emphasize the different activities involved in planned organizational change implementation (namely, communicating the need for change, mobilizing others to support the change, and evaluating the change implementation). We examine this relationship using data from 89 clinical managers at the United Kingdom National Health Service who implemented change projects between 2003 and 2004. Our results lend overall support to the proposed theory. This finding suggests that treating planned organizational change as a generic phenomenon might mask important idiosyncrasies associated both with the different activities involved in the change implementation process and with the unique functions that leadership competencies might play in the execution of these activities.

Practicing a musical instrument in childhood is associated with enhanced verbal ability and nonverbal reasoning.

Abstract: Background: In this study we investigated the association between instrumental music training in childhood and outcomes closely related to music training as well as those more distantly related. Methodology/Principal Findings: Children who received at least three years (M=4.6 years) of instrumental music training outperformed their control counterparts on two outcomes closely related to music (auditory discrimination abilities and fine motor skills) and on two outcomes distantly related to music (vocabulary and nonverbal reasoning skills). Duration of training also predicted these outcomes. Contrary to previous research, instrumental music training was not associated with heightened spatial skills, phonemic awareness, or mathematical abilities. Conclusions/Significance: While these results are correlational only, the strong predictive effect of training duration suggests that instrumental music training may enhance auditory discrimination, fine motor skills, vocabulary, and nonverbal reasoning. Alternative explanations for these results are discussed.