21 research outputs found
Trends in book-tax income and balance sheet differences.
Conference paperWe use Compustat and tax return data to describe trends from 1991-1998 in differences
between book and tax measures of income and balance sheet amounts. Our primary findings
confirm that book-tax income differences are growing throughout the 1990s. Extending prior
work, we partition the sample to describe the differences by industry, global character and
profitability. Secondly, we compare Compustat financial statement assets and liabilities to the
book balance sheet reported on the tax return and find that the tax return amounts exceed the
financial statement amounts in the aggregate. We plan to investigate suggested explanations for
this excess, including differences in book versus tax consolidation reporting and off-balance
sheet activity
Gravitational field around a screwed superconducting cosmic string in scalar-tensor theories
We obtain the solution that corresponds to a screwed superconducting cosmic
string (SSCS) in the framework of a general scalar-tensor theory including
torsion. We investigate the metric of the SSCS in Brans-Dicke theory with
torsion and analyze the case without torsion. We show that in the case with
torsion the space-time background presents other properties different from that
in which torsion is absent. When the spin vanish, this torsion is a
-gradient and then it propagates outside of the string. We investigate
the effect of torsion on the gravitational force and on the geodesics of a
test-particle moving around the SSCS. The accretion of matter by wakes
formation when a SSCS moves with speed is investigated. We compare our
results with those obtained for cosmic strings in the framework of
scalar-tensor theory.Comment: 22 pages, LaTeX, presented at the "XXII - Encontro Nacional de Fisica
de Particulas e Campos", Sao Lourenco, MG, Brazi
Gravitational field around a time-like current-carrying screwed cosmic string in scalar-tensor theories
In this paper we obtain the space-time generated by a time-like
current-carrying superconducting screwed cosmic string(TCSCS). This
gravitational field is obtained in a modified scalar-tensor theory in the sense
that torsion is taken into account. We show that this solution is comptible
with a torsion field generated by the scalar field . The analysis of
gravitational effects of a TCSCS shows up that the torsion effects that appear
in the physical frame of Jordan-Fierz can be described in a geometric form
given by contorsion term plus a symmetric part which contains the scalar
gradient. As an important application of this solution, we consider the linear
perturbation method developed by Zel'dovich, investigate the accretion of cold
dark matter due to the formation of wakes when a TCSCS moves with speed and
discuss the role played by torsion. Our results are compared with those
obtained for cosmic strings in the framework of scalar-tensor theories without
taking torsion into account.Comment: 21 pages, no figures, Revised Version, presented at the "XXIV-
Encontro Nacional de Fisica de Particulas e Campos ", Caxambu, MG, Brazil, to
appear in Phys. Rev.
A connectome and analysis of the adult Drosophila central brain.
The neural circuits responsible for animal behavior remain largely unknown. We summarize new methods and present the circuitry of a large fraction of the brain of the fruit fly Drosophila melanogaster. Improved methods include new procedures to prepare, image, align, segment, find synapses in, and proofread such large data sets. We define cell types, refine computational compartments, and provide an exhaustive atlas of cell examples and types, many of them novel. We provide detailed circuits consisting of neurons and their chemical synapses for most of the central brain. We make the data public and simplify access, reducing the effort needed to answer circuit questions, and provide procedures linking the neurons defined by our analysis with genetic reagents. Biologically, we examine distributions of connection strengths, neural motifs on different scales, electrical consequences of compartmentalization, and evidence that maximizing packing density is an important criterion in the evolution of the fly's brain
Economic Effects of Media Concentration: Estimates from a Model of the Newspaper Firm.
By specifying and estimating a five-equation model of newspaper operations, this paper provides evidence useful for addressing several issues concerning media concentration. On the cost side, the results indicate that there exist significant scale economies in the production of circulation and space. On the other hand, the evidence suggests that chain newspapers can not produce output more efficiently than independents, all things equal. On the demand side, rival newspapers located in contiguous geographic markets appear to have an important competitive effect on the demand for circulation. However, broadcast stations do not seem to affect demand for newspaper advertising and circulation. Copyright 1990 by Blackwell Publishing Ltd.
Mechanochemically Active Soft Robots
The functions of soft robotics are
intimately tied to their formî—¸channels
and voids defined by an elastomeric superstructure that reversibly
stores and releases mechanical energy to change shape, grip objects,
and achieve complex motions. Here, we demonstrate that covalent polymer
mechanochemistry provides a viable mechanism to convert the same mechanical
potential energy used for actuation in soft robots into a mechanochromic,
covalent chemical response. A bis-alkene functionalized spiropyran
(SP) mechanophore is cured into a molded polyÂ(dimethylsiloxane) (PDMS)
soft robot walker and gripper. The stresses and strains necessary
for SP activation are compatible with soft robot function. The color
change associated with actuation suggests opportunities for not only
new color changing or camouflaging strategies, but also the possibility
for simultaneous activation of latent chemistry (e.g., release of
small molecules, change in mechanical properties, activation of catalysts,
etc.) in soft robots. In addition, mechanochromic stress mapping in
a functional robotic device might provide a useful design and optimization
tool, revealing spatial and temporal force evolution within the robot
in a way that might be coupled to autonomous feedback loops that allow
the robot to regulate its own activity. The demonstration motivates
the simultaneous development of new combinations of mechanophores,
materials, and soft, active devices for enhanced functionality
Mechanochemically Active Soft Robots
The functions of soft robotics are
intimately tied to their formî—¸channels
and voids defined by an elastomeric superstructure that reversibly
stores and releases mechanical energy to change shape, grip objects,
and achieve complex motions. Here, we demonstrate that covalent polymer
mechanochemistry provides a viable mechanism to convert the same mechanical
potential energy used for actuation in soft robots into a mechanochromic,
covalent chemical response. A bis-alkene functionalized spiropyran
(SP) mechanophore is cured into a molded polyÂ(dimethylsiloxane) (PDMS)
soft robot walker and gripper. The stresses and strains necessary
for SP activation are compatible with soft robot function. The color
change associated with actuation suggests opportunities for not only
new color changing or camouflaging strategies, but also the possibility
for simultaneous activation of latent chemistry (e.g., release of
small molecules, change in mechanical properties, activation of catalysts,
etc.) in soft robots. In addition, mechanochromic stress mapping in
a functional robotic device might provide a useful design and optimization
tool, revealing spatial and temporal force evolution within the robot
in a way that might be coupled to autonomous feedback loops that allow
the robot to regulate its own activity. The demonstration motivates
the simultaneous development of new combinations of mechanophores,
materials, and soft, active devices for enhanced functionality