Minimizing Seed Set Selection with Probabilistic Coverage Guarantee in a Social Network

A topic propagating in a social network reaches its tipping point if the number of users discussing it in the network exceeds a critical threshold such that a wide cascade on the topic is likely to occur. In this paper, we consider the task of selecting initial seed users of a topic with minimum size so that with a guaranteed probability the number of users discussing the topic would reach a given threshold. We formulate the task as an optimization problem called seed minimization with probabilistic coverage guarantee (SM-PCG). This problem departs from the previous studies on social influence maximization or seed minimization because it considers influence coverage with probabilistic guarantees instead of guarantees on expected influence coverage. We show that the problem is not submodular, and thus is harder than previously studied problems based on submodular function optimization. We provide an approximation algorithm and show that it approximates the optimal solution with both a multiplicative ratio and an additive error. The multiplicative ratio is tight while the additive error would be small if influence coverage distributions of certain seed sets are well concentrated. For one-way bipartite graphs we analytically prove the concentration condition and obtain an approximation algorithm with an $O(\log n)$ multiplicative ratio and an $O(\sqrt{n})$ additive error, where $n$ is the total number of nodes in the social graph. Moreover, we empirically verify the concentration condition in real-world networks and experimentally demonstrate the effectiveness of our proposed algorithm comparing to commonly adopted benchmark algorithms.Comment: Conference version will appear in KDD 201

Recollements induced by left Frobenius pairs

Let $T$ be a right exact functor from an abelian category $\mathscr{B}$ into another abelian category $\mathscr{A}$. Then there exists an abelian category, named comma category and denoted by $(T\downarrow\mathscr{A})$.In this paper, we construct left Frobenius pairs (resp. strong left Frobenius pairs) over $(T\downarrow\mathscr{A})$ using left Frobenius pairs (resp. strong left Frobenius pairs) over $\mathscr{A}$ and $\mathscr{B}.$ As a consequence, we obtain a recollement of (right) triangulated categories, generalizing the result of Xiong-Zhang-Zhang (J. Algebra 503 (2018) 21-55) about the recollement of additive (resp. triangulated) categories constructed from a triangular matrix algebra. This result is applied to the classes of flat modules and Gorenstein flat modules, the classes of Gorenstein projective modules and Gorenstein projective complexes, the class of Ding projective modules and the class of Gorenstein flat-cotorsion modules.Comment: 24 pages, all comments are welcom

Tetraethyl 2,2′-(2,3,5,6-tetrafluoro-p-phenylenedimethylene)dipropanoate1

In the mol­ecule of the title compound, C22H26F4O8, a crystallographic inversion centre is located at the centroid of the benzene ring. C—H⋯F and C—H⋯O intra­molecular hydrogen bonds are observed as well as an inter­molecular C—H⋯O inter­action

2,2′-(p-Phenyl­enedimethyl­ene)bis­(propane-1,3-diol)

The mol­ecule of the title compound, C14H22O4, is centrosymmetric. In the crystal, the mol­ecules are linked through O—H⋯O hydrogen bonds into a three-dimensional network

1,4-Bis[3-chloro-2-(chloro­meth­yl)prop­yl]benzene

The title mol­ecule, C14H18Cl4, possesses a crystallographically imposed inversion centre, which coincides with the centre of benzene ring. In the absence of classical inter­molecular inter­actions, van der Waals forces help the mol­ecules to pack in the crystal

CRISPR/Cas9: implication for modeling and therapy of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a deadly neurological disease with a complicated and variable pathophysiology yet to be fully understood. There is currently no effective treatment available to either slow or terminate it. However, recent advances in ALS genomics have linked genes to phenotypes, encouraging the creation of novel therapeutic approaches and giving researchers more tools to create efficient animal models. Genetically engineered rodent models replicating ALS disease pathology have a high predictive value for translational research. This review addresses the history of the evolution of gene editing tools, the most recent ALS disease models, and the application of CRISPR/Cas9 against ALS disease

Probing darK Matter Using free leptONs: PKMUON

We propose a new method to detect sub-GeV dark matter, through their scatterings from free leptons and the resulting kinematic shifts. Specially, such an experiment can detect dark matter interacting solely with muons. The experiment proposed here is to directly probe muon-philic dark matter, in a model-independent way. Its complementarity with the muon on target proposal, is similar to, e.g. XENON/PandaX and ATLAS/CMS on dark matter searches. Moreover, our proposal can work better for relatively heavy dark matter such as in the sub-GeV region. We start with a small device of a size around 0.1 to 1 meter, using atmospheric muons to set up a prototype. Within only one year of operation, the sensitivity on cross section of dark matter scattering with muons can already reach $\sigma_D\sim 10^{-19 (-20,\,-18)}\rm{cm}^{2}$ for a dark mater $\rm{M_D}=100\, (10,\,1000)$ MeV. We can then interface the device with a high intensity muon beam of $10^{12}$/bunch. Within one year, the sensitivity can reach $\sigma_D\sim 10^{-27 (-28,\,-26)}\rm{cm}^{2}$ for $\rm{M_D}=100\, (10,\,1000)$ MeV.Comment: 5 pages, 3 figures, muons enlighten darknes

Lateral curtain interception technology and water conservation effect in groundwater abundant mines of China

There are many types and numbers of mines in China, covering coal, metallurgy, non-ferrous metals, chemical industry and so on. Most of the mines use dewatering and drainage to control groundwater, and some of the water abundant mines have tens of thousands of m3 to hundreds of thousands of m3 of mine drainage per day, which causes the problems of declining groundwater level, water resources depletion, karst collapse and ground subsidence, surface water pollution, and deterioration of groundwater environment. In order to solve the problem of safe mining and water waste in water abundant mines, research on mine water cut-off curtain technology has been carried out since 1960 s, and after nearly 60 years of development, it has developed from single ground straight drilling and grouting to various water cut-off curtain technologies such as ground directional drilling and grouting, downhole drilling and grouting, combined drilling and grouting up and down the shaft, row of piles, continuous wall and seepage control membrane, etc. In more than 80 mines, semi-closed, closed, drop-bottom and suspended water interception curtains have been successfully applied, with water interception rate mostly above 60% and water level on the outside of the curtain significantly raised, achieving very good application results and protecting mine water resources and mine ecological environment. Four typical water interception curtain cases, such as metal mine karst fissure water fully closed curtain, coal mine bedrock drop bottom type slurry curtain, loose layer and karst stratum directional horizontal hole slurry curtain, loose layer impermeable membrane drop bottom type curtain, were selected for detailed elaboration, and the water interception technology and water resource protection effect of typical water interception curtain cases were analyzed, and the effective water interception rate was above 75%. Based on the development trend of curtain water interception technology, it is proposed that the technologies of continuous jointless water curtain in the lateral direction of loose layer, directional diffusion grouting in the lateral water curtain of bedrock, and lateral water curtain in the thick grass-roots level with low permeability are future directions, so as to practice the concept of “Green Mountains Are Mountains of Gold”, to protect the groundwater resources of mine, and to realize water conservation, ecology conservation, loss reduction and green mining

Immunomodulatory role of estrogen in ischemic stroke: neuroinflammation and effect of sex

Although estrogen is predominantly related to the maintenance of reproductive functioning in females, it mediates various physiological effects in nearly all tissues, especially the central nervous system. Clinical trials have revealed that estrogen, especially 17β-estradiol, can attenuate cerebral damage caused by an ischemic stroke. One mechanism underlying this effect of 17β-estradiol is by modulating the responses of immune cells, indicating its utility as a novel therapeutic strategy for ischemic stroke. The present review summarizes the effect of sex on ischemic stroke progression, the role of estrogen as an immunomodulator in immune reactions, and the potential clinical value of estrogen replacement therapy. The data presented here will help better understand the immunomodulatory function of estrogen and may provide a basis for its novel therapeutic use in ischemic stroke

Asymptotically optimal strategy-proof mechanisms for two-facility games

ABSTRACT We consider the problem of locating facilities in a metric space to serve a set of selfish agents. The cost of an agent is the distance between her own location and the nearest facility. The social cost is the total cost of the agents. We are interested in designing strategy-proof mechanisms without payment that have a small approximation ratio for social cost. A mechanism is a (possibly randomized) algorithm which maps the locations reported by the agents to the locations of the facilities. A mechanism is strategy-proof if no agent can benefit from misreporting her location in any configuration. This setting was first studied by Procaccia and Tennenholtz We first prove an Ω(n) lower bound of the social cost approximation ratio for deterministic strategy-proof mechanisms. Our lower bound even holds for the line metric space. This significantly improves the previous constant lower bound