Paid Placement: Advertising and Search on the Internet

Paid placement, where advertisers bid payments to a search engine to have their products appear next to keyword search results, has emerged as a predominant form of advertising on the Internet. This paper studies a product-di¤erentiation model where consumers are initially uncertain about the desirability of and valuation for di¤erent sellers products, and can learn about a seller s product through a costly search. In equilibrium, a seller bids more for placement when his product is more relevant for a given keyword, and the paid placement of sellers by the search engine reveals information about the relevance of their products. This results in e¢ cient (sequential) search by consumers and increases total output

Engineering grain boundaries at the 2D limit for the hydrogen evolution reaction

Atom-thin transition metal dichalcogenides (TMDs) have emerged as fascinating materials and key structures for electrocatalysis. So far, their edges, dopant heteroatoms and defects have been intensively explored as active sites for the hydrogen evolution reaction (HER) to split water. However, grain boundaries (GBs), a key type of defects in TMDs, have been overlooked due to their low density and large structural variations. Here, we demonstrate the synthesis of wafer-size atom-thin TMD films with an ultra-high-density of GBs, up to ~1012 cm−2. We propose a climb and drive 0D/2D interaction to explain the underlying growth mechanism. The electrocatalytic activity of the nanograin film is comprehensively examined by micro-electrochemical measurements, showing an excellent hydrogen-evolution performance (onset potential: −25 mV and Tafel slope: 54 mV dec−1), thus indicating an intrinsically high activation of the TMD GBs

Enhanced Photoelectrochemical Water Splitting of Hematite Multilayer Nanowires Photoanode with Tuning Surface State via Bottom-up Interfacial Engineering

The optimization of multiple interfaces in hematite (α-Fe_2O_3) based composites for photoelectrochemical water splitting to facilitate charge transport in the bulk is of paramount importance to obtain enhanced solar-to-fuel efficiency. Herein, we report the fabrication of ITO/Fe_2O_3/Fe_2TiO_5/FeNiOOH multi-layer nanowires and a series of systematic experiments designed to elucidate the mechanism underlying the interfacial coupling effect of the quaternary hematite composite. The hierarchical ITO/Fe_2O_3/Fe_2TiO_5/FeNiOOH nanowires display photocurrents that are more than an order of magnitude greater than those of pristine Fe_2O_3 nanowires (from 0.205 mA cm^(−2) to 2.2 mA cm^(−2) at 1.23 V vs. RHE and 1 Sun), and higher than those of most of the recently reported state-of-the-art hematite composites. Structural, compositional and electrochemical investigations disclose that the surface states (SS) are finely regulated via the atomic addition of an Fe_2TiO_5 layer and FeNiOOH nanodots, while the upgrading of back contact conductivity and charge donor densities originate from the epitaxial relationship and enhanced Sn doping contributed from the ITO underlayer. We attribute the superior water oxidation performance to the interfacial coupling effect of the ITO underlayer (Sn doping and back contact conductivity promoter), the atomic level Fe_2TiO_5 coating (Ti doping, surface state density and energy level modulation) and the FeNiOOH nanodot electrocatalyst (regulating surface state energy level). Our work suggests an effective pathway for rational designing of highly active and cost-effective integrated photoanodes for photoelectrochemical water splitting

Enhanced photoelectrochemical water splitting of hematite multilayer nanowire photoanodes by tuning the surface state via bottom-up interfacial engineering

The optimization of multiple interfaces in hematite (α-Fe₂O₃) based composites for photoelectrochemical water splitting to facilitate charge transport in the bulk is of paramount importance to obtain enhanced solar-to-fuel efficiency. Herein, we report the fabrication of ITO/Fe₂O₃/Fe₂TiO₅/FeNiOOH multi-layer nanowires and a series of systematic experiments designed to elucidate the mechanism underlying the interfacial coupling effect of the quaternary hematite composite. The hierarchical ITO/Fe₂O₃/Fe₂TiO₅/FeNiOOH nanowires display photocurrents that are more than an order of magnitude greater than those of pristine Fe₂O₃ nanowires (from 0.205 mAcm⁻² to 2.2 mAcm⁻² at 1.23 V vs. RHE and 1 Sun), and higher than those of most of the recently reported state-of-the-art hematite composites. Structural, compositional and electrochemical investigations disclose that the surface states (SS) are finely regulated via the atomic addition of an Fe₂TiO₅ layer and FeNiOOH nanodots, while the upgrading of back contact conductivity and charge donor densities originate from the epitaxial relationship and enhanced Sn doping contributed from the ITO underlayer. We attribute the superior water oxidation performance to the interfacial coupling effect of the ITO underlayer (Sn doping and back contact conductivity promoter), the atomic level Fe₂TiO₅ coating (Ti doping, surface state density and energy level modulation) and the FeNiOOH nanodot electrocatalyst (regulating surface state energy level). Our work suggests an effective pathway for rational designing of highly active and cost-effective integrated photoanodes for photoelectrochemical water splitting

SegRap2023: A Benchmark of Organs-at-Risk and Gross Tumor Volume Segmentation for Radiotherapy Planning of Nasopharyngeal Carcinoma

Radiation therapy is a primary and effective NasoPharyngeal Carcinoma (NPC) treatment strategy. The precise delineation of Gross Tumor Volumes (GTVs) and Organs-At-Risk (OARs) is crucial in radiation treatment, directly impacting patient prognosis. Previously, the delineation of GTVs and OARs was performed by experienced radiation oncologists. Recently, deep learning has achieved promising results in many medical image segmentation tasks. However, for NPC OARs and GTVs segmentation, few public datasets are available for model development and evaluation. To alleviate this problem, the SegRap2023 challenge was organized in conjunction with MICCAI2023 and presented a large-scale benchmark for OAR and GTV segmentation with 400 Computed Tomography (CT) scans from 200 NPC patients, each with a pair of pre-aligned non-contrast and contrast-enhanced CT scans. The challenge's goal was to segment 45 OARs and 2 GTVs from the paired CT scans. In this paper, we detail the challenge and analyze the solutions of all participants. The average Dice similarity coefficient scores for all submissions ranged from 76.68\% to 86.70\%, and 70.42\% to 73.44\% for OARs and GTVs, respectively. We conclude that the segmentation of large-size OARs is well-addressed, and more efforts are needed for GTVs and small-size or thin-structure OARs. The benchmark will remain publicly available here: https://segrap2023.grand-challenge.orgComment: A challenge report of SegRap2023 (organized in conjunction with MICCAI2023

Rating Inflation versus Deflation: On Procyclical Credit Ratings

Credit rating agencies play a crucial role in financial markets. There are two competing views regarding their behavior: some argue that they engage in rating inflation, while others suggest that they deflate ratings. This article offers a rationale that reconciles the two opposite arguments. We find that both rating inflation and rating deflation can occur in equilibrium. Furthermore, we show that credit rating is procyclical: rating inflation is more likely to happen in a boom while rating deflation is more likely to happen in a recession

Paid Placement: Advertising and Search on the Internet

Paid placement, where advertisers bid payments to a search engine to have their products appear next to keyword search results, has emerged as a predominant form of advertising on the Internet. This paper studies a product-di¤erentiation model where consumers are initially uncertain about the desirability of and valuation for di¤erent sellers? products, and can learn about a seller?s product through a costly search. In equilibrium, a seller bids more for placement when his product is more relevant for a given keyword, and the paid placement of sellers by the search engine reveals information about the relevance of their products. This results in e¢ cient (sequential) search by consumers and increases total output.Paid placement, Advertising, Auction, E-commerce, Search

Recent Progress in Chemical Syntheses of Sphingosines and Phytosphingosines

International audienceSphingolipids and their derivatives such as glycosphingolipids and sphingomyelins exist ubiquitously in biomembrane of all eukaryotic cells, which play pivotal roles in cell proliferation, recognition, adhesion, and signal transduction. Sphingosine is shown to be the important lipid moiety in the large majority of glycosphingolipids and sphingomyelins, while phytosphingosine is one of the major long-chain moieties of glycosphingo-lipids. Due to the significance of the two bioactive lipids, tremendous efforts have been made to synthesize sphingosine or phytosphingosine using chiral pool approaches, chiral auxiliary and asymmetric reactions to construct the continuous stereogenic centers in them. This review covers the synthetic literatures published in the year after 2000

Expression of MYSM1 is associated with tumor progression in colorectal cancer.

Colorectal cancer, the third most common cancer in both men and women, has gradually increased in recent years. MYSM1has been investigated as a regulator of hematopoiesis and lymphocyte development in human. It has been reported that some tumor-related genes were modulated by MYSM1. However, its exact role in cancer development remains unclear. Herein, we aimed to examine the expression level of MYSM1 in tumor tissues and its correlation with clinicopathology and survivals of patients with colorectal cancer (CRC).MYSM1expressions in tumor specimens resected from 123 CRC patients were detected by immunochemistry and Western blot analysis. The results showed that MYSM1 was significantly highly expressed in carcinoma tissues compared with adjacent normal mucosa tissues (P<0.05). Correlation analyses by Pearson's chi-square test demonstrated that MYSM1 in tumors was positively correlated with tumor status (pathological assessment of the primary tumor (pT, P<0.001), regional lymph nodes (pN, P = 0.013), distant metastasis (pM, P<0.001)) and clinic stage (P<0.001); Whereas, MYSM1 was not associated with tumor size of CRC patients and was positively associated with tumor differentiation grade (P = 0.015). Patients with positiveMYSM1expression showed poor survival compared with the MYSM1 negative group (P<0.001).Simultaneously, multivariate Cox regression analysis indicated thatMYSM1 expression in tumor cells was an independent factor for reduced overall survival in CRC patients (P<0.001).Additionally,MYSM1 in CRC SW480 cells was silenced by small interference RNA (siRNA) technology. Scratch assay and Transwell assay showed that MYSM1 silencing decreased migration and invasion abilities of SW480 cells. These data suggested that expression of MYSM1 was associated with the progression of CRC and might be a potential biomarker for clinical prognosis