The Value of Live Chat on Online Purchase

In this paper, we empirically investigate the value of live chatting tools on purchase. We use a clickstream data from a leading online marketplace where live chats between e-tailers and customers are documented. We follow the classic two-stage choice model proposed by Moe (2006), and incorporate the choice of chatting as a new stage. In our model, consumers make a sequence of three stages of choices. In the first stage, they choose a product to view; In the second stage, they decide on whether to initiate a live chat; In the third stage, they decide on whether to purchase. This process iterate until consumers decide to stop. We find that consumers choose products with low price and high reputation in the first stage. They request live chat when e-tellers\u27 reputation is low and the price is low. Finally, live chat has positive impact over purchase, especially for low-reputation e-tailers

An Examination of Social Comparison Triggered by Higher Donation Visibility over Social Media Platforms

With the recent development of social media, social networking sites have become an important channel for charitable fundraising. Some social networking sites, like Facebook and Weibo, initiate their own charitable campaigns by collaborating with nonprofit organizations. By changing donation visibility, social media platforms can alter the level of social comparison and affect users’ donation patterns. Using individual-level data from a microblogging platform where a donation service is embedded, we investigate how individual donation decisions are influenced by the visibility of donation information. We find that despite the platform designer’s desire to improve fundraising performance, higher visibility of donors’ contributions may have a negative impact on fundraising. We also find that donations made by users’ followees generally have a positive impact on users’ propensity to donate. On the contrary, donations made by the crowd only positively affect a subset of users, while they have a negative impact on other users

Quantitative weighted estimates for the multilinear pseudo-differential operators in function spaces

In this paper, the weighted estimates for multilinear pseudo-differential operators were systematically studied in rearrangement invariant Banach and quasi-Banach spaces. These spaces contain the Lebesgue space, the classical Lorentz space and Marcinkiewicz space as typical examples. More precisely, the weighted boundedness and weighted modular estimates, including the weak endpoint case, were established for multilinear pseudo-differential operators and their commutators. As applications, we show that the above results also hold for the multilinear Fourier multipliers, multilinear square functions, and a class of multilinear Calder\'{o}n-Zygmund operators.Comment: 31 pages,added one sentence in page 3 and a referenc

Observation of forbidden phonons and dark excitons by resonance Raman scattering in few-layer WS2_2

The optical properties of the two-dimensional (2D) crystals are dominated by tightly bound electron-hole pairs (excitons) and lattice vibration modes (phonons). The exciton-phonon interaction is fundamentally important to understand the optical properties of 2D materials and thus help develop emerging 2D crystal based optoelectronic devices. Here, we presented the excitonic resonant Raman scattering (RRS) spectra of few-layer WS$_2$ excited by 11 lasers lines covered all of A, B and C exciton transition energies at different sample temperatures from 4 to 300 K. As a result, we are not only able to probe the forbidden phonon modes unobserved in ordinary Raman scattering, but also can determine the bright and dark state fine structures of 1s A exciton. In particular, we also observed the quantum interference between low-energy discrete phonon and exciton continuum under resonant excitation. Our works pave a way to understand the exciton-phonon coupling and many-body effects in 2D materials.Comment: 14 pages, 11 figure

Composition of rough singular integral operators on rearrangement invariant Banach type spaces

Let $\Omega$ be a homogeneous function of degree zero and enjoy the vanishing condition on the unit sphere $\mathbb{S}^{n-1}(n\geq 2)$. Let $T_{\Omega}$ be the convolution singular integral operator with kernel ${\Omega(x)}{|x|^{-n}}$. In this paper, when $\Omega \in L^{\infty}(\mathbb {S}^{n-1})$, we consider the quantitative weighted bounds of the composite operators of $T_{\Omega}$ on rearrangement invariant Banach function spaces. These spaces contain the classical Lorentz spaces and Orlicz spaces as special examples. Weighted boundedness of the composite operators on rearrangement invariant quasi-Banach spaces were also given.Comment: 21 page