arXiv subjects

Yang Zhou

Publications and source records attributed to Yang Zhou.

518 records · Page 29Linked to original sources

arXiv2012

The Impact of Visual Appearance on User Response in Online Display Advertising

Display advertising has been a significant source of revenue for publishers and ad networks in online advertising ecosystem. One of the main goals in display advertising is to maximize user response rate for advertising campaigns, such as click through rates (CTR) or conversion rates. Although in the online advertising industry we believe that the visual appearance of ads (creatives) matters for propensity of user response, there is no published work so far to address this topic via a systematic data-driven approach. In this paper we quantitatively study the relationship between the visual appearance and performance of creatives using large scale data in the world's largest display ads exchange system, RightMedia. We designed a set of 43 visual features, some of which are novel and some are inspired by related work. We extracted these features from real creatives served on RightMedia. We also designed and conducted a series of experiments to evaluate the effectiveness of visual features for CTR prediction, ranking and performance classification. Based on the evaluation results, we selected a subset of features that have the most important impact on CTR. We believe that the findings presented in this paper will be very useful for the online advertising industry in designing high-performance creatives. It also provides the research community with the first ever data set, initial insights into visual appearance's effect on user response propensity, and evaluation benchmarks for further study.

cs.HC↗

arXiv2011

Structure Learning of Probabilistic Graphical Models: A Comprehensive Survey

Probabilistic graphical models combine the graph theory and probability theory to give a multivariate statistical modeling. They provide a unified description of uncertainty using probability and complexity using the graphical model. Especially, graphical models provide the following several useful properties: - Graphical models provide a simple and intuitive interpretation of the structures of probabilistic models. On the other hand, they can be used to design and motivate new models. - Graphical models provide additional insights into the properties of the model, including the conditional independence properties. - Complex computations which are required to perform inference and learning in sophisticated models can be expressed in terms of graphical manipulations, in which the underlying mathematical expressions are carried along implicitly. The graphical models have been applied to a large number of fields, including bioinformatics, social science, control theory, image processing, marketing analysis, among others. However, structure learning for graphical models remains an open challenge, since one must cope with a combinatorial search over the space of all possible structures. In this paper, we present a comprehensive survey of the existing structure learning algorithms.

stat.ML↗

arXiv2011

Mixed RG Flows and Hydrodynamics at Finite Holographic Screen

We consider quark-gluon plasma with chemical potential and study renormalization group flows of transport coefficients in the framework of gauge/gravity duality. We first study them using the flow equations and compare the results with hydrodynamic results by calculating the Green functions on the arbitrary slice. Two results match exactly. Transport coefficients at arbitrary scale is ontained by calculating hydrodynamics Green functions. When either momentum or charge vanishes, transport coefficients decouple from each other.

hep-th↗

arXiv2011

Holographic Wilsonian RG Flow and Sliding Membrane Paradigm

We study the relations between two different approaches to the holographic Renormalization Group (RG) flow at the dual gravity level: One is the radial evolution of the classical equation of motion and the other is the flow equation given by the holographic Wilsonian RG coming from the cut off independence. Apparently, the two flows look different. We give general proofs that the two flows are actually equivalent. The role of the momentum continuity (MC) is essential. We show that MC together with cutoff independence gives the evolution equation of the boundary values. Equivalence of conductivity flows in two paradigm has been shown as an explicit example. We also get the connecting formula of Green functions and AC conductivity at arbitrary slice in terms of its value at horizon for various geometry backgrounds.

hep-th↗

arXiv2011

Holographic Superconductor for a Lifshitz fixed point

We consider the gravity dual of strongly coupled system at a Lifshitz-fixed point and finite temperature, which was constructed in a recent work arXiv:0909.0263. We construct an Abelian Higgs model in that background and calculate condensation and conductivity using holographic techniques. We find that condensation happens and DC conductivity blows up when temperature turns below a critical value.

hep-th↗

arXiv2009

From Liouville to Chern-Simons, Alternative Realization of Wilson Loop Operators in AGT Duality

We propose an SL(2,R) Chern-Simons description of Liouville field theory (LFT), whose correlation function duals to partition function of N=2 SU(2) gauge theories. We give the dual expressions for conformal blocks, fusion rules, and Wilson loop operators in Chern-Simons theory. By realizing Wilson loop operator in Liouville as a Hopf link in S^3 on which lives an SL(2,R) Chern-Simons theory, we obtain an alternative description of monodromy of this loop operator in Liouville field theory as the ratio of link invariants. We show how to calculate t'Hooft loops in the simplest example -- the N=4 super Yang-Mills theory. The results we obtained are consistant with those in 0909.0945 and 0909.1105.

hep-th↗

arXiv2009

A Note on Wilson Loop in N=2 Quiver/M theory Gravity Duality

We study Wilson loops in the 4-dimensional N=2 supersymmetric quiver/M theory duality recently constructed by Gaiotto and Maldacena, that is conjectured to be dual to M2 branes on AdS_5\times S^4 fibered over Σ_2. We use the localization method raised by Pestun, in order to compute the Wilson loop in 4-dimensional N=2 supersymmetric linear quiver gauge theory. We obtained the consistent results in the quiver gauge theory and the 11-dimensional supergravity. This match supports the N=2 quiver SCFT / M theory supergravity duality.

hep-th↗

arXiv2009

Holographic melting of Heavy Baryons in Plasma with Gluon Condensation

We propose a Dirac-Born-Infeld (DBI) D5 vertex brane plus N_c fundamental strings configuration to describe a baryon probe in strongly coupled gauge theory with gluon condensation at finite temperature via AdS/CFT correspondence. We investigate properties of this configuration in a dilaton deformed AdS_5\times S^5 background, in which IIB string theroy is dual to super Yang-Mills thery in a state with a constant self-dual gauge field (F_{mn}=F^*_{mn}) background. We find that for most values of temperature T and gluon condensation parameter q (q = π^2 ), there always exists a screening length L_s. The relation L_s\sim{1\ov T} has been checked. We give the q dependence of L_s. We calculate the boost velocity v(v=-\tanhη) and angular velocity ωdependence of L_s for a baryon probe, and obtain L_s=L_0*(1-v^2)^{1/4} for large v and L_s\simω^{-1}, which are consistent with those dependence relations in the point brane plus strings case, and find that the usual relations have been modified by q. We also calculate the mass of baryon and find T dependence of baryon mass.

hep-th↗

arXiv2009

Comments on Baryon Melting in Quark Gluon Plasma with Gluon Condensation

We consider a black hole solution with a non-trivial dilaton from IIB super gravity which is expected to describe a strongly coupled hot gauge plasma with non-vanishing gluon condensation present. We construct a rotating and moving baryon to probe the screening and phases of the plasma. Melting of the baryons in hot plasma in this background had been studied previously, however, we show that baryons melt much lower temperature than has been suggested previously.

hep-th↗

arXiv2009

A Holographic model for Non-Relativistic Superconductor

We build a holographic description of non-relativistic system for superconductivity in strongly interacting condensed matter via gauge/gravity duality. We focus on the phase transition and give an example to show that a simple gravitational theory can provide a non-relativistic holographical dual description of a superconductor. There is also a critical temperature like the relativistic case, below which a charged condensation field appears by a second order phase transition and the (DC) conductivity becomes infinite. We also calculated the frequency dependent conductivity.

hep-th↗

arXiv2009

D4 brane probes in gauge/gravity duality

We propose a DBI vertex brane + $N_c$ fundamental strings configuration for a probe baryon in the finite-temperature thermal gauge field via AdS/CFT correspondence. In particular, we investigate properties of this configuration in QCD_4 and warped AdS_6\times S^4. We find that, in D4-D8 system, a holographic probe baryon can be described as N_c fundamental strings connecting through a vertex D4 brane wrapped on S^4. In QCD_4 background, a closed vertex can exist in confined phase and can not exist in deconfined phase. In the low temperature region, screening effect still exist in confined phase like meson and the vertex D4 brane dominates the baryon mass. The lower energy state corresponds to vertex brane closer to the radial cut off position (r=r_c) and the higher energy state corresponds to vertex brane a little far away from the cut off position. The high energy limit of this configuration is just like the unclosed vertex brane configuration in a higher temperature deconfined phase. In warped AdS_6\times S^4 background, a closed vertex can exist in deconfined phase and the vertex contains a spike, while fundamental strings are relatively short. Screening length should be defined through the distance between top position of the vertex spike and the boundary.

hep-th↗

arXiv2009

A note on interpreting N M2 branes

A new world volume theory with a free scalar field was proposed for Multiple M2 branes recently. By giving the free scalar a large VEV, we can obtain a gauge theory of multiple D2 branes with a coupling constant proportional to the VEV. It is pointed out by Banerjee and Sen that we can get D2 branes by choosing a compactification in the $θ$ direction, with radial position having the same value of the VEV. Following this work, we try to describe the multiple M2 branes in R^8/Z_K and give a simple provement of g_{YM} \propto {1 \ov \sqrt{K}} in the compactification. We try to interpret T^0 and T^{-1} as the radial coordinate operator and momentum operator and give some evidences in geometry and quantum mechanics.

hep-th↗

arXiv2008

High spin baryon in hot strongly coupled plasma

We consider a strings-junction holographic model of probe baryon in the finite-temperature supersymmetric Yang-Mills dual of the AdS-Schwarzschild black hole background. In particular, we investigate the screening length for high spin baryon composed of rotating N_c heavy quarks. To rotate quarks by finite force, we put hard infrared cutoff in the bulk and give quarks finite mass. We find that N_c microscopic strings are embedded reasonably in the bulk geometry when they have finite angular velocity ω, similar to the meson case. By defining the screening length as the critical separation of quarks, we compute the ωdependence of the baryon screening length numerically and obtain a reasonable result which shows that baryons with high spin dissociate more easily. Finally, we discuss the relation between J and E^2 for baryons.

hep-th↗

arXiv2002

Generalized Competing Glauber-type Dynamics and Kawasaki-type Dynamics

In this article, we have given a systematic formulation of the new generalized competing mechanism: the Glauber-type single-spin transition mechanism, with probability p, simulates the contact of the system with the heat bath, and the Kawasaki-type spin-pair redistribution mechanism, with probability 1-p, simulates an external energy flux. These two mechanisms are natural generalizations of Glauber's single-spin flipping mechanism and Kawasaki's spin-pair exchange mechanism respectively. On the one hand, the new mechanism is in principle applicable to arbitrary systems, while on the other hand, our formulation is able to contain a mechanism that just directly combines single-spin flipping and spin-pair exchange in their original form. Compared with the conventional mechanism, the new mechanism does not assume the simplified version and leads to greater influence of temperature. The fact, order for lower temperature and disorder for higher temperature, will be universally true. In order to exemplify this difference, we applied the mechanism to 1D Ising model and obtained analytical results. We also applied this mechanism to kinetic Gaussian model and found that, above the critical point there will be only paramagnetic phase, while below the critical point, the self-organization as a result of the energy flux will lead the system to an interesting heterophase, instead of the initially guessed antiferromagnetic phase. We studied this process in details.

cond-mat.dis-nn↗