114 research outputs found
Evolution of Conversations in the Age of Email Overload
Email is a ubiquitous communications tool in the workplace and plays an
important role in social interactions. Previous studies of email were largely
based on surveys and limited to relatively small populations of email users
within organizations. In this paper, we report results of a large-scale study
of more than 2 million users exchanging 16 billion emails over several months.
We quantitatively characterize the replying behavior in conversations within
pairs of users. In particular, we study the time it takes the user to reply to
a received message and the length of the reply sent. We consider a variety of
factors that affect the reply time and length, such as the stage of the
conversation, user demographics, and use of portable devices. In addition, we
study how increasing load affects emailing behavior. We find that as users
receive more email messages in a day, they reply to a smaller fraction of them,
using shorter replies. However, their responsiveness remains intact, and they
may even reply to emails faster. Finally, we predict the time to reply, length
of reply, and whether the reply ends a conversation. We demonstrate
considerable improvement over the baseline in all three prediction tasks,
showing the significant role that the factors that we uncover play, in
determining replying behavior. We rank these factors based on their predictive
power. Our findings have important implications for understanding human
behavior and designing better email management applications for tasks like
ranking unread emails.Comment: 11 page, 24th International World Wide Web Conferenc
Strong and Radiative Meson Decays in a Generalized Nambu--Jona-Lasinio Model
We investigate strong and radiative meson decays in a generalized
Nambu--Jona-Lasinio model. The one loop order calculation provides a
satisfactory agreement with the data for the mesonic spectrum and for radiative
decays. Higher order effects for strong decays of and are
estimated to be large. We also discuss the role of the flavour mixing
determinantal interaction.Comment: 7 pages, LaTeX, 2 figs available upon request, CRN 92-4
Low-energy dynamics of the reaction
We calculate the one-quark-loop amplitude for the low energy
collision in the context of the Nambu and Jona-Lasinio
model with scalar and pseudoscalar four quark couplings to all orders in the
external momenta. We show that the NJL predictions for the
reaction are not far from the Born amplitude, which
is close to the data, and is compatible with the chiral perturbation theory
estimations. We determine the corrections given by the NJL model in leading
order of to the chiral loop amplitude for .
Numerical results for the cross sections and
for pion polarizabilities are given.Comment: 20 pages in LaTex, 3 figures in 1 Postscript fil
Stationary phase corrections in the process of bosonization of multi-quark interactions
The functional integration over the auxiliary bosonic variables of cubic
order related with the effective action of the Nambu -- Jona-Lasinio model with
't Hooft term has recently been obtained in the form of a loop expansion. Even
numbers of loops contribute to the action, while odd numbers of loops are
assigned to the measure. We consider the two-loop corrections and analyse their
effect on the low-lying pseudoscalar and scalar mass spectra, quark condensates
and weak decay constants. The results are compared to the leading order
calculations and other approaches.Comment: 22 pages, LaTeX, to appear in European Physics Journal
Consistency in Regularizations of the Gauged NJL Model at One Loop Level
In this work we revisit questions recently raised in the literature
associated to relevant but divergent amplitudes in the gauged NJL model. The
questions raised involve ambiguities and symmetry violations which concern the
model's predictive power at one loop level. Our study shows by means of an
alternative prescription to handle divergent amplitudes, that it is possible to
obtain unambiguous and symmetry preserving amplitudes. The procedure adopted
makes use solely of {\it general} properties of an eventual regulator, thus
avoiding an explicit form. We find, after a thorough analysis of the problem
that there are well established conditions to be fulfiled by any consistent
regularization prescription in order to avoid the problems of concern at one
loop level.Comment: 22 pages, no figures, LaTeX, to appear in Phys.Rev.
Lowering the critical temperature with eight-quark interactions
It is shown that eight-quark interactions, which are needed to stabilize the
ground state of the combined three flavor Nambu -- Jona-Lasinio and 't Hooft
Lagrangians, play also an important role in determining the critical
temperature at which transitions occur from the dynamically broken chiral phase
to the symmetric phase.Comment: 4 pages, 2 figure
Momentum Dependent Vertices , and : The NJL Scalar Hidden by Chiral Symmetry
We calculate the momentum dependence of three particle vertices , and in the context of a
Nambu Jona Lasinio type model. We show how they influence the processes , and and how chiral symmetry
shadows the presence of the .Comment: 9 pages (latex), 5 figures available from the authors, preprint
Coimbra 940506, IJS-TP-94/10, accepted for publication in Zeit. f. Physik
OZI violating eight-quark interactions as a thermometer for chiral transitions
This work is a follow-up of our recent observation that in the SU(3) flavor
limit with vanishing current quark masses the temperature for the chiral
transition is substantially reduced by adding eight-quark interactions to the
Nambu - Jona-Lasinio Lagrangian with U_A(1) breaking. Here we generalize the
case to realistic light and strange quark masses and confirm our prior result.
Additionally, we demonstrate that depending on the strength of OZI violating
eight-quark interactions, the system undergoes either a rapid crossover or a
first order phase transition. The meson mass spectra of the low lying
pseudoscalars and scalars at T=0 are not sensitive to the difference in the
parameter settings that correspond to these two alternatives, except for the
singlet-octet mixing scalar channels, mainly the sigma meson.Comment: LaTeX, 5 pages, 3 figure
Diquark Bose Condensates in High Density Matter and Instantons
Instantons lead to strong correlations between up and down quarks with spin
zero and anti-symmetric color wave functions. In cold and dense matter,
and 50 MeV, these pairs Bose-condense,
replacing the usual and
condensates.Comment: 4 pages ReVTeX, 2 eps-figures included using epsf.st
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