Optimal Allocation Mechanisms When Bidders Ranking for the objects is common

Search engines commonly use “sponsored linksâ€, where certain advertisers’ links are promoted to be placed above others in return for monetary payment. It is natural to assume that all providers value a higher ranked placement more than lower ranked ones. Then how should the seller optimally sell these ranked slots is critical for the search engines. In this paper we study the seller’s (search engine) optimal selling mechanism in the following setting: buyers (advertisers), each of whom has unit demand, compete for positions oered by the seller. While each buyer’s valuation for each position is private and independent, the ranking for these positions is common among all the buyers. However the rate at which these valuations change might be dierent. We begin with 4 simplified scenarios specifying how buyers valuations change for dierent positions, namely,“parallelâ€, “convergentâ€, “divergentâ€, and “convergent then divergentâ€. We find that the optimal incentive compatible allocation mechanism is quite dierent in determining the “pivot†types and the order to fill in the positions. Under some conditions, these mechanisms are even ecient in terms of maximizing the total welfare of the auctioneer and bidders. When the buyers’ valuations for lower positions decrease at dierent rates, the seller earns more than the case of simple second-price sequential auctionoptimal auction, mechanism design, heterogeneous objects, ranking

Teleportation of an arbitrary multipartite state via photonic Faraday rotation

We propose a practical scheme for deterministically teleporting an arbitrary multipartite state, either product or entangled, using Faraday rotation of the photonic polarization. Our scheme, based on the input-output process of single-photon pulses regarding cavities, works in low-Q cavities and only involves virtual excitation of the atoms, which is insensitive to both cavity decay and atomic spontaneous emission. Besides, the Bell-state measurement is accomplished by the Faraday rotation plus product-state measurements, which could much relax the experimental difficulty to realize the Bell-state measurement by the CNOT operation.Comment: 11 pages, 2 figures

A Bio-MEMS device for separation of breast cancer cells from peripheral whole blood

This work demonstrates the application of Bio-Micro Electro Mechanical System (Bio-MEMS) technology for early breast cancer detection and diagnosis. Early breast cancer detection and diagnosis typically uses conventional mammogram screening followed by biopsy, which can be problematic since mammography can only detect highly calcified tumors greater than 1 cm in size. A micro-device was developed to identify and specifically collect tumor cells of low abundance (1 tumor cell among 107 normal blood cells) from circulating whole blood. By immobilizing anti-EpCAM (Epithelial Cell Adhesion Molecule) antibodies on polymer micro-channel walls by the chemical surface modification of PMMA, breast cancer cells from the cell line MCF-7, which over-express EpCAM on their surfaces, were caught by the strong binding affinity between the antibody and antigen. To validate the capture of the rare breast cancer cells, three fluorescence markers, each identified by a separate color, were used to reliably distinguish the cancer cells from blood cells. The cancer cells were defined by DAPI+ (blue), CD45- and the FITC-cell membrane linker+ (green). White blood cells, which will interfere in the detection of the cancer cells, were identified by DAPI+ (blue), CD45+ (red), and the FITC-cell membrane linker+ (green). Three EpCAM/Anti-EpCAM binding models were used to determine an optimal velocity, 2mm/sec, which should guarantee the binding of the maximum number of cells, a critical binding force, and a maximum throughput. At higher velocities, shear forces (\u3e 0.48 dyne) will break existing bonds and prevent formation of new ones. This detection micro-device can be assembled with other lab-on-a-chip components for follow- up gene and protein marker analysis

A balancing act? An empirical examination of whether the dynamic balance policy has helped China reduce cultivated land loss amid rapid urban land expansion

For decades, the Chinese government has been concerned about its ability to meet the grain self-sufficiency goal due to the depletion of cultivated land caused by urbanization and industrialization. The Dynamic Balance Policy (DBP) was initiated in 1998 to balance China's need to protect cultivated land with the need to provide land for urban and industrial development. The DBP is a "no net loss" policy which requires local government to keep their good-quality cultivated land at the current level. If cultivated land is converted to other uses, an equal amount of other land, adjusted for the quality, must be converted to cultivation to compensate for the loss. Empirical evidence suggests that the DBP has had no effects of reducing cultivated land loss in China. Economic incentives, such as the values of urban and cultivated land, emerge as the most influential factors for China's land use changes. Moreover, these economic incentives may have overridden the effects of the DBP, if any. Polices can be made more effective to address the windfall profits in land acquisition and conveyance, and offer economic incentives for not converting cultivated land to urban uses. This dissertation conducts a systematic examination of the effects of the DBP of curbing the rate of cultivated land conversion. In particular, it develops a theoretical model of land conversion that combines the institutional structure of land use in China and the incentive structure of Chinese local officials whose goal is to promote local economies and budgetary balances. This model serves as the theoretical foundation for the empirical examination. The empirical implementation of the land conversion model uses the official land use data provided by the Ministry of Land and Resources of China and economic data published in various issues of provincial statistical yearbooks. This is a unique set of data which combines China's official land use data and economic data at the prefecture level and covers a period of rapid economic growth and prominent changes in land uses from 1996 to 2004

One-loop renormalization of the electroweak chiral Lagrangian with a light Higgs

We consider the general chiral effective action which parametrizes the nonlinear realization of the spontaneous breaking of the electroweak symmetry with a light Higgs, and compute the one-loop ultraviolet divergences coming from Higgs and electroweak Goldstone fluctuations using the background field method. The renormalization of the divergences is carried out through operators of next-to-leading order in the chiral counting, i.e. of O(p^4). Being of the same order in power counting, the logarithmic corrections linked to these divergences can be as important as the tree-level contributions from the O(p^4) operators, and must be accounted for in the phenomenological analysis of experimental data. Deviations in the O(p^2) (leading-order) couplings with respect to the Standard Model values, e.g., in the h->WW coupling, would generate contributions from the 1-loop chiral logarithms computed in this work to a vast variety of observables, which do not have a counterpart in the conventional electroweak effective theory with a linearly transforming Higgs complex doublet.Comment: 6 page

Zc(3900)Z_c(3900): what has been really seen?

The $Z^\pm_c(3900)/Z^\pm_c(3885)$ resonant structure has been experimentally observed in the $Y(4260) \to J/\psi \pi\pi$ and $Y(4260) \to \bar{D}^\ast D \pi$ decays. This structure is intriguing since it is a prominent candidate of an exotic hadron. Yet, its nature is unclear so far. In this work, we simultaneously describe the $\bar{D}^\ast D$ and $J/\psi \pi$ invariant mass distributions in which the $Z_c$ peak is seen using amplitudes with exact unitarity. Two different scenarios are statistically acceptable, where the origin of the $Z_c$ state is different. They correspond to using energy dependent or independent $\bar D^* D$ $S$-wave interaction. In the first one, the $Z_c$ peak is due to a resonance with a mass around the $D\bar D^*$ threshold. In the second one, the $Z_c$ peak is produced by a virtual state which must have a hadronic molecular nature. In both cases the two observations, $Z^\pm_c(3900)$ and $Z^\pm_c(3885)$, are shown to have the same common origin, and a $\bar D^* D$ bound state solution is not allowed. Precise measurements of the line shapes around the $D\bar D^*$ threshold are called for in order to understand the nature of this state.Comment: 6 pages, 6 figure