856 research outputs found
Ethical aspects of e-commerce: data subjects and content
This paper reflects on the ethical challenges posed by Internet commerce, with special emphasis on those involving the content and the users of the information. The paper discusses the main ethical issues in e-commerce, including security, privacy, identity and nonrefutability of transactions. It proposes measures which both governments and the private sector could adopt to address those issues on different levels. Finally, the paper reflects on the creation of value by leveraging trust and proposes two universal principles to be upheld in Internet commerce: online-offline consistency and technological neutrality.Security; privacy; identity; nonrefutability; e-commerce ethics;
Ground-state 12CO emission and a resolved jet at 115 GHz (rest-frame) in the radio loud quasar 3C318
An analysis of 44 GHz VLA observations of the z = 1.574 radio-loud quasar
3C318 has revealed emission from the redshifted J = 1 - 0 transition of the CO
molecule and spatially resolved the 6.3 kpc radio jet associated with the
quasar at 115 GHz rest-frame. The continuum-subtracted line emitter is
spatially offset from the quasar nucleus by 0.33" (2.82 kpc in projection).
This spatial offset has a significance of >8-sigma and, together with a
previously published -400 km/s velocity offset measured in the J = 2 - 1 CO
line relative to the systemic redshift of the quasar, rules out a circumnuclear
starburst or molecular gas ring and suggests that the quasar host galaxy is
either undergoing a major merger with a gas-rich galaxy or is otherwise a
highly disrupted system. If the merger scenario is correct then the event may
be in its early stages, acting as the trigger for both the young radio jets in
the quasar and a starburst in the merging galaxy. The total molecular gas mass
in the spatially offset line emitter as measured from the ground-state CO line
M_H2 = 3.7 (+/-0.4) x 10^10 (alpha_CO/0.8) M_solar. Assuming that the
line-emitter can be modelled as a rotating disk, an inclination-dependent upper
limit is derived for its dynamical mass M_dyn sin^2(i) < 3.2 x 10^9 M_solar,
suggesting that for M_H2 to remain less than M_dyn the inclination angle must
be i < 16 degrees. The far infrared and CO luminosities of 246 extragalactic
systems are collated from the literature for comparison. The high molecular gas
content of 3C318 is consistent with that of the general population of high
redshift quasars and sub-millimetre galaxies.Comment: 10 pages, 4 figures, 2 tables (additional table to appear online as
supplementary material), accepted for publication in MNRA
On the nonlinear stability of mKdV breathers
A mathematical proof for the stability of mKdV breathers is announced. This
proof involves the existence of a nonlinear equation satisfied by all breather
profiles, and a new Lyapunov functional which controls the dynamics of small
perturbations and instability modes. In order to construct such a functional,
we work in a subspace of the energy one. However, our proof introduces new
ideas in order to attack the corresponding stability problem in the energy
space. Some remarks about the sine-Gordon case are also considered.Comment: 7 p
Collective Coordinates Theory for Discrete Soliton Ratchets in the sine-Gordon Model
A collective coordinate theory is develop for soliton ratchets in the damped
discrete sine-Gordon model driven by a biharmonic force. An ansatz with two
collective coordinates, namely the center and the width of the soliton, is
assumed as an approximated solution of the discrete non-linear equation. The
evolution of these two collective coordinates, obtained by means of the
Generalized Travelling Wave Method, explains the mechanism underlying the
soliton ratchet and captures qualitatively all the main features of this
phenomenon. The theory accounts for the existence of a non-zero depinning
threshold, the non-sinusoidal behaviour of the average velocity as a function
of the difference phase between the harmonics of the driver, the non-monotonic
dependence of the average velocity on the damping and the existence of
non-transporting regimes beyond the depinning threshold. In particular it
provides a good description of the intriguing and complex pattern of subspaces
corresponding to different dynamical regimes in parameter space
Orbital stability of the black soliton for the quintic Gross-Pitaevskii equation
In this work, a rigorous proof of the orbital stability of the black soliton
solution of the quintic Gross-Pitaevskii equation in one spatial dimension is
obtained. We first build and show explicitly black and dark soliton solutions
and we prove that the corresponding Ginzburg-Landau energy is coercive around
them by using some orthogonality conditions related to perturbations of the
black and dark solitons. The existence of suitable perturbations around black
and dark solitons satisfying the required orthogonality conditions is deduced
from an Implicit Function Theorem. In fact, these perturbations involve dark
solitons with sufficiently small speeds and some proportionality factors
arising from the explicit expression of their spatial derivative. We are also
able to control the evolution of the modulation parameters along the quintic
Gross-Pitaevskii flow by estimating their growth in time. Finally by using a
low order conservation law (momentum), we prove that the speed of the
perturbation is bounded and use that control to finish the proof of the orbital
stability of black solitons. As a direct consequence, we also prove the orbital
stability of the dark soliton in a small speed interval.Comment: 46 pages, 3 figures. Introduction extende
Hacia una teorĂa de la empresa basada en el bien comĂşn
Las consideraciones habituales sobre la naturaleza de la empresa dependen en gran medida de las explicaciones de Coase, junto con las aportaciones procedentes de la teorĂa de la agencia y la teorĂa de los accionistas. A pesar de las exigencias de objetividad y neutralidad, ha sido difĂcil proporcionar un lugar a un tipo de Ă©tica empresarial que reconozca la naturalezaz personal del ser humano y la contribuciĂłn de las empresas al bien comĂşn segĂşn esas premisas. Este artĂculo empieza presentando las suposiciones de Coase que están implĂcitas en la teorĂa de las agencia y despuĂ©s expone su crĂtica a la luz de los postulados personalistas y del bien comĂşn. Pretende mostrar cĂłmo los principios del personalismo y del bien comĂşn crean un marco que no sĂłlo se acomoda mejor a la Ă©tica empresarial, sino que tambiĂ©n permite una comprensiĂłn más convincente de la empresa como un todo
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