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Competing for attention in social communication markets
We investigate the incentives for social communication in the new social media technologies. Three features of online social communication are represented in the model. First, new social media platforms allow for increased connectivity; i.e., they enable sending messages to many more receivers, for the same fixed cost, compared to traditional word of mouth. Second, users contribute content because they derive status- or image-based utility from being listened to by their peers. Third, we capture the role of social differentiation, or how social distance between people affects their preferences for messages. In the model, agents endogenously decide whether to be a sender of information and then compete for the attention of receivers. An important point of this paper is that social communication incentives diminish even as the reach or the span of communication increases. As the span of communication increases, competition between senders for receiver attention becomes more intense, resulting in senders competing with greater equilibrium messaging effort. This in turn leads to lower equilibrium payoffs and the entry of fewer senders. This result provides a strategic rationale for the socalled participation inequality phenomenon, which is a characteristic of many social media platforms. We also show that social differentiation may enhance or deter sender entry depending on whether it can be endogenously influenced by senders. Finally, we examine how the underlying network structure (in terms of its density and its degree distribution) affects communication and uncover a nonmonotonic pattern in that increased connectivity first increases and then reduces the entry of senders
Classical and Quantum Aspects of Gravitation and Cosmology
These are the proceedings of the XVIII Conference of the Indian Association
for General Relativity and Gravitation (IAGRG) held at the Institute of
Mathematical Sciences, Madras, INDIA during Feb. 15-17, 1996. The Conference
was dedicated the late Prof. S. Chandrasekhar.
The proceedings consists of 17 articles on:
- Chandrasekhar's work (N. Panchapkesan);
- Vaidya-Raychaudhuri Lecture (C.V. Vishveshwara)
- Gravitational waves (B.R. Iyer, R. Balasubramanian)
- Gravitational Collapse (T.P. Singh)
- Accretion on black hole (S. Chakrabarti)
- Cosmology (D. Munshi, S. Bharadwaj, G.S. Mohanty, P. Bhattacharjee);
- Classical GR (S. Kar, D.C. Srivatsava)
- Quantum aspects (J. Maharana, Saurya Das, P. Mitra, G. Date, N.D. Hari
Dass)
The body of THIS article contains ONLY the title, contents, foreword,
organizing committees, preface, list of contributed talks and list of
participants. The plenery talks are available at:
http://www.imsc.ernet.in/physweb/Conf/ both as post-script files of individual
articles and also as .uu source files. For further information please send
e-mail to [email protected]: 12 pages, latex, needs psfig.tex macros. Latex the file run.tex.
These Proceedings of the XVIII IAGRG Conference are available at
http://www.imsc.ernet.in/physweb/Conf/ MINOR TYPO's in the ABSTRACT correcte
Moving Signals and Their Measured Frequencies
In determining the classical Doppler Effect, two assumptions are used for
computing the difference in distance travelled by consecutive signals: (a) the
receptor is stationary, and (b) the emitter is stationary. The calculated
Doppler Effect under the two assumptions are identical, provided the velocity
of propagation with respect to source and the velocity of propagation with
respect to the receptor differ exactly by the velocity of relative motion. We
show that, in the case of light, the ratio of the two calculated classical
Doppler Effects, with propagation speed c in the source and receptor inertial
frames respectively, remains constant in all geometries and orientations.
Furthermore, the observed Doppler Effect, as predicted by special relativity,
is the geometric mean of the two expected classical Doppler Effects in all
geometries and orientations. This leads to two simultaneous conclusions: (1) by
the receptor that the clock associated with the emitter runs slow, and (2) by
the emitter that the clock associated with the receptor runs slow. These
differences can be resolved if we theorize that light travels at speed c with
respect to the emitter as it leaves the emitter and travels at speed c with
respect to the receptor as it approaches the receptor.Comment: Revised in accordance with peer review process; Published August 2013
in Int. J. Engg. Res. & Sci & Tech 2(3) pp 24-3
Differing perceptions on the landing of the rod into the slot
In the usual rod and slot paradox, the rod, if it falls, was expected to fall
into the slot due to gravity. Many thought experiments have been conducted
where the presence of gravity is eliminated with the rod and slot approaching
each other along a line joining their centers, whereby the considerations come
strictly under Special Relativity. In these experiments the line of motion is
not parallel to either the axis of the rod or the slot. In this paper we
consider in detail the two cases when the rod does fall into the slot and when
the rod does not fall into the slot, each from the perspective of the co-moving
frames of the rod and the slot. We show that whether the rod falls into the
slot as determined by Galilean kinematics is also valid under relativistic
kinematics; this determination does not depend upon the magnitude of the
velocity, but only on the proper lengths and the proper angles of the rod and
slot with the line of motion. Our conclusion emphasizes the fact that the
passing (or crashing) of the rod as a wholesome event is unaffected by
relativistic kinematics. We also provide a simple formula to determine whether
or not the rod passes through the slot.Comment: 9 pages, 6 figure
A Model of Two Dimensional Turbulence Using Random Matrix Theory
We derive a formula for the entropy of two dimensional incompressible
inviscid flow, by determining the volume of the space of vorticity
distributions with fixed values for the moments Q_k= \int_w(x)^k d^2 x. This
space is approximated by a sequence of spaces of finite volume, by using a
regularization of the system that is geometrically natural and connected with
the theory of random matrices. In taking the limit we get a simple formula for
the entropy of a vortex field. We predict vorticity distributions of maximum
entropy with given mean vorticity and enstrophy; also we predict the
cylindrically symmetric vortex field with maximum entropy. This could be an
approximate description of a hurricane.Comment: latex, 12 pages, 2 figures, acknowledgement adde
Miniaturized Circular-Waveguide Probe Antennas Using Metamaterial Liners
This work presents the radiation performance of open-ended circular-waveguide
probe antennas that have been miniaturized by the introduction of thin
metamaterial liners. The liners introduce an HE mode well below the
natural cutoff frequency, which provides substantial gain improvements over a
similarly sized waveguide probe. A new feeding arrangement employing a
shielded-loop source embedded inside the miniaturized waveguide is developed to
efficiently excite the HE mode and avoid the excitation of other modes
across the frequency reduced band while maintaining the antenna's compactness.
A metamaterial-lined circular-waveguide probe antenna operating over 42% below
its natural cutoff frequency is designed to provide a radiation efficiency of
up to 28.8%. A simple, printed-circuit implementation of the metamaterial liner
based on inductively loaded wires is proposed and its dispersion features are
discussed.Comment: The manuscript has been revised for publication as a 6 page
communication in the IEEE Transactions on Antennas and Propagation. This
included a reduction of material in the theory section, removal of all
discussion on anisotropic theory, and introduction of a novel excitation
sourc
Analog-digital simulation of transient-induced logic errors and upset susceptibility of an advanced control system
A simulation study is described which predicts the susceptibility of an advanced control system to electrical transients resulting in logic errors, latched errors, error propagation, and digital upset. The system is based on a custom-designed microprocessor and it incorporates fault-tolerant techniques. The system under test and the method to perform the transient injection experiment are described. Results for 2100 transient injections are analyzed and classified according to charge level, type of error, and location of injection
Fission-fusion dynamics and group-size dependent composition in heterogeneous populations
Many animal groups are heterogeneous and may even consist of individuals of
different species, called mixed-species flocks. Mathematical and computational
models of collective animal movement behaviour, however, typically assume that
groups and populations consist of identical individuals. In this paper, using
the mathematical framework of the coagulation-fragmentation process, we develop
and analyse a model of merge and split group dynamics, also called
fission-fusion dynamics, for heterogeneous populations that contain two types
(or species) of individuals. We assume that more heterogeneous groups
experience higher split rates than homogeneous groups, forming two daughter
groups whose compositions are drawn uniformly from all possible partitions. We
analytically derive a master equation for group size and compositions and find
mean-field steady-state solutions. We predict that there is a critical group
size below which groups are more likely to be homogeneous and contain the
abundant type/species. Despite the propensity of heterogeneous groups to split
at higher rates, we find that groups are more likely to be heterogeneous but
only above the critical group size. Monte-Carlo simulation of the model show
excellent agreement with these analytical model results. Thus, our model makes
a testable prediction that composition of flocks are group-size dependent and
do not merely reflect the population level heterogeneity. We discuss the
implications of our results to empirical studies on flocking systems.Comment: 19 pages, 8 figure
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