10,859 research outputs found
Combining Traditional Marketing and Viral Marketing with Amphibious Influence Maximization
In this paper, we propose the amphibious influence maximization (AIM) model
that combines traditional marketing via content providers and viral marketing
to consumers in social networks in a single framework. In AIM, a set of content
providers and consumers form a bipartite network while consumers also form
their social network, and influence propagates from the content providers to
consumers and among consumers in the social network following the independent
cascade model. An advertiser needs to select a subset of seed content providers
and a subset of seed consumers, such that the influence from the seed providers
passing through the seed consumers could reach a large number of consumers in
the social network in expectation.
We prove that the AIM problem is NP-hard to approximate to within any
constant factor via a reduction from Feige's k-prover proof system for 3-SAT5.
We also give evidence that even when the social network graph is trivial (i.e.
has no edges), a polynomial time constant factor approximation for AIM is
unlikely. However, when we assume that the weighted bi-adjacency matrix that
describes the influence of content providers on consumers is of constant rank,
a common assumption often used in recommender systems, we provide a
polynomial-time algorithm that achieves approximation ratio of
for any (polynomially small) . Our
algorithmic results still hold for a more general model where cascades in
social network follow a general monotone and submodular function.Comment: An extended abstract appeared in the Proceedings of the 16th ACM
Conference on Economics and Computation (EC), 201
The relationship between high density lipoprotein subclass profile and plasma lipids concentrations
HDL particles posses multiple antiatherogenic activities and the identification and differentiation of individual HDL subclasses may be useful in documentation and understanding of metabolic changes of different HDL subclasses. The major plasma lipids exist and are transported in the form of lipoprotein complexes. Hence, alterations in plasma lipids levels can interfere with the composition, content, and distribution of plasma lipoprotein subclasses that affect atherosclerosis risk. The research review major discussed the relationship between plasma lipids levels and HDL subclasses distribution. The general shift toward smaller size of HDL particle size in HTG, HCL and MHL subjects, and the changes were more prominent with the elevation of TG and TC levels which imply that HDL maturation might be abnormal and RCT pathway might be weaken, and these changes were more seriously in MHL subjects. Plasma contents of small sized HDL particles significantly higher, whereas those of large sized HDL particles were significantly lower with elevation of TG/HDL-C and TC/HDL-C ratios. Increased in the TC/HDL-C ratio alone did not influence the distributions of HDL subclasses significantly when the TG/HDL-C ratio was low (TG/HDL-C ⤠2.5). Hence, the TG/HDL-C ratio might be more sensitive to reflect the alteration of HDL subclass distribution than the TC/HDL-C ratio. In LDL-C/HDL-C ⤠2.3 group, the pattern of distribution in HDL subclass was in agreement with the normolipidemic subjects. Moreover, considering the relative ease of measuring TC/HDL-C, TG/HDL-C and LDL-C/HDL-C ratios, as opposed to measuring HDL subclasses, these 3 ratios together may be a good indicator of HDL subclass distribution. The protective effect of increased apoA-I levels against the reduction of HDL2b caused by elevated TG concentration. On one hand, plasma HDL-C and apoA-I appear to play a coordinated role in the assembly of HDL particles and the determination of their contents among the total subjects. On the other hand, the apoA-I level might be a more powerful factor than HDL-C to influence the distribution of HDL subclasses in hyperlipidemic subjects. At the same time, from point of HDL subclasses distribution, the plasma lipids, apos concentrations and apos ratios should be considered while assessing the CHD risk. Abnormality of HDL subclasses distribution may result in accelerated atherosclerosis, therapeutic normalization of attenuated antiatherogenic HDL function in terms of both particle number and distribution of HDL particles is the target of innovative pharmacological approaches to large-sized HDL particles rising, including enhanced apoA-I levels
Development of a 3-D Position Sensitive Neutron Detector Based on Organic Scintillators with Double Side SiPM Readout
A 3-D position sensitive neutron detector is being developed based on a
plastic scintillator array. A double side SiPM readout is used to determine the
depth of interaction (DOI) in each scintillator unit. In the preliminary test,
the DOI in a 254 x 6 x 6 mm3 SP101 plastic scintillator is measured at
different positions using a collimated Co-60 source. The SiPM (KETEK PM6660)
signals are recorded by a 2.5 GS/s digital oscilloscope. The DOI results are
calculated using both the amplitude and the temporal information. Position
resolutions (FWHM) of 2.5 cm and 6.6 cm are realized, respectively. A detector
based on a 2-D array is capable of recording the 3-D position information of
the incident neutron. The 3-D detector is to be used together with a neutron
time projection chamber as a directional fast neutron detector. According to
the simulation results, the angular resolution (8 degree FWHM) is much better
than that of a typical neutron scatter camera.Comment: 7 pages, 7 figures, submitted to IEEE NSS MIC 201
Acceleration-extended Newton-Hooke symmetry and its dynamical realization
Newton-Hooke group is the nonrelativistic limit of de Sitter (anti-de Sitter)
group, which can be enlarged with transformations that describe constant
acceleration, as well as central charges. We consider a higher order Lagrangian
that is quasi-invariant under the acceleration-extended Newton-Hooke symmetry,
and obtain the Schr\"{o}dinger equation quantizing the Hamiltonian
corresponding to its first order form. We show that the Schr\"{o}dinger
equation is invariant under the acceleration-extended Newton-Hooke
transformations. We also discuss briefly the exotic conformal Newton-Hooke
symmetry in 2+1 dimension.Comment: 14 pages, revtex4; refs added, misleading statements revised, version
to appear in Phys. Lett.
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