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Background: The concept of serendipity has become increasingly interesting for those undertaking serendipity research in recent years. However, serendipitous encounters are subjective and rare in a real-world context, making this an extremely challenging subject to study. Methods: Various methods have been proposed to enable researchers to understand and measure serendipity, but there is no broad consensus on which methods to use in different experimental settings. A comprehensive literature review was first conducted, which summarizes the research methods being employed to study serendipity. It was followed by a series of interviews with experts that specified the relative strengths and weaknesses of each method identified in the literature review, in addition to the challenges usually confronted in serendipity research. Results: The findings suggest using mixed research methods to produce a more complete picture of serendipity and contribute to the verification of any research findings. Several challenges and implications relating to empirical studies in the investigation of serendipity have been derived from this study. Conclusions: This paper investigated research methods employed to study serendipity by synthesizing finding from a literature review and the interviews with experts. It provides a methodological contribution to serendipity studies by systematically summarizing the methods employed in the studies of serendipity and identifying the strengths and weakness of each method. It also suggests the novel approach of using mixed research methods to study serendipity. This study has potential limitations related to a small number of experts involved in the expert interview. However, it should be noted that the nature of the topic is a relatively focused area, and it was observed after interviewing the experts that new data seems to not contribute to the findings owing to its repetition of comments. [ABSTRACT FROM AUTHOR]

We examine how managerial ability is associated with stock repurchase activity. Adopting the managerial efficiency score developed by Demerjian, Lev, and McVay (2012) as the proxy for managerial ability, we explore the link between managerial ability and stock repurchase based on a total number of 85,480 firm-year observations in the U.S. from 1980 to 2016. We find that firms with higher managerial ability are more likely to conduct share repurchases and spend more on repurchasing shares. Our findings are robust to using alternative measure of managerial ability, controlling for unobservable variables and the impact of dividend tax cut of 2003, and addressing potential endogeneity concerns. In addition, talented managers tend to repurchase shares instead of issuing more dividends. Firms with high-ability managers reduce overinvestment in favor of repurchases. This study contributes to the literature of managerial traits on corporate decisions. [ABSTRACT FROM AUTHOR]

Highly energy-efficient and stable electrocatalysts for hydrogen evolution reaction (HER) are very important for sustainable and clean energy technologies, but are limited by sluggish anodic oxygen evolution reaction (OER). In this work, we develop a strategy using a self-supported MOF nanorod arrays, [Ni3(BTC)2/NiF] as bifunctional catalyst for integrating energy-saving HER and replacement of OER by the thermodynamically more favorable electro-oxidation of sodium gluconate (ECSG) to high-value glucaric acid. The Ni3(BTC)2/NiF only require a cell voltage of 1.22 V to drive 100 mA cm-2 in KOH solution with sodium gluconate (SG), which is significantly reduced by 400 mV relative to the alkaline solution without SG. The assembled [Ni3(BTC)2/NiF||Ni3(BTC)2/NiF] couple behaves nearly 100% Faradic efficiency for HER at the cathode and SG conversion of 100% with glucaric acid selectivity of 97.9% at the anode, and long-term durability. Such an integration of HER and oxidative biomass to high-value-added chemical provides a new way to maximize the energy conversion efficiency. [ABSTRACT FROM AUTHOR]

In recent years, with the rapid development of Internet technology, agricultural production has been promoted, and digital agriculture, precision agriculture, intelligent agriculture and so on have been formed. The intelligence of information system is an important development trend of network construction. From the point of view of promoting agricultural informatization, this paper designs an intelligent agricultural regional information matching system based on block chain technology. The reliability and robustness of the system are guaranteed by using the characteristics of block chain, such as non-tampering and security encryption. Combined with the network of edge computing, computing and storage service resources, the acquisition, data processing and storage of large-scale intelligent agricultural area information are realized. Thus, an intelligent agricultural system is constructed, and a comprehensive, open and multifunctional agricultural science and technology information system under the network environment is gradually built. To achieve the purpose of effectively improving the production efficiency of agricultural products, it is of practical significance for the application of intelligent information technology in the field of agriculture and the exploration of network system from general information service to knowledge service. At the same time, it provides consumers with comprehensive information on the production of agricultural products. [ABSTRACT FROM AUTHOR]

β-Ionone and β-cyclocitral are two typical components in cyanobacterial volatiles, which can poison aquatic plants and even cause death. To reveal the toxic mechanisms of the two compounds on aquatic plants through programmed cell death (PCD), the photosynthetic capacities, caspase-3-like activity, DNA fragmentation and ladders, as well as expression of the genes associated with PCD in Lemna turionifera were investigated in exposure to β-ionone (0.2 mM) and β-cyclocitral (0.4 mM) at lethal concentration. With prolonging the treatment time, L. turionifera fronds gradually died, and photosynthetic capacities gradually reduced and even disappeared at the 96th h. This demonstrated that the death process might be a PCD rather than a necrosis, due to the gradual loss of physiological activities. When L. turionifera underwent the death, caspase-3-like was activated after 3 h, and reached to the strongest activity at the 24th h. TUNEL-positive nuclei were detected after 12 h, and appeared in large numbers at the 48th h. The DNA was cleaved by Ca2+-dependent endonucleases and showed obviously ladders. In addition, the expression of 5 genes (TSPO , ERN1 , CTSB , CYC , and ATR) positively related with PCD initiation was up-regulated, while the expression of 2 genes (RRM2 and TUBA) negatively related with PCD initiation was down-regulated. Therefore, β-ionone and β-cyclocitral can poison L. turionifera by adjusting related gene expression to trigger PCD. [Display omitted] • β-Ionone and β-cyclocitral killed L. turionifera with physiology gradually losing. • Caspase-3-like was activated during the death, and TUNEL-positive nuclei were found. • DNA showed laddering, which was cleaved by Ca2+-dependent endonucleases. • Expression of 7 genes related with PCD was adjusted to initiate L. turionifera death. [ABSTRACT FROM AUTHOR]

Background/purpose: Robotic approach has improved the ergonomics of conventional laparoscopic distal pancreatectomy (LDP), but whether patients benefit more from robot assisted distal pancreatectomy (RADP) is still controversial. This meta-analysis aims to compare the perioperative and economic outcomes of RADP with LDP.Methods: A systematic review of the literature was carried out on PubMed, EMBASE, and the Cochrane Library between January 1990 and March 2017. All eligible studies comparing RADP versus LDP were included. Perioperative and economic outcomes constituted the end points.Results: 13 English studies with 1396 patients were included. Regarding to intraoperative outcomes, RADP was associated with a significant decrease in conversion rate (OR = 0.52; 95%CI: 0.34, 0.78; P = 0.002). Although the spleen-preserving rates were comparable between RADP and LDP, a significant higher splenic vessels conservation rate was observed in the RADP group (OR = 4.71; 95%CI: 1.77, 12.56; P = 0.002). No statistically significant differences were found at operation time, estimated blood loss and blood transfusion rate. Concerning postoperative outcomes, pooled data indicated the overall morbidity, pancreatic fistula and the length of hospital stay did not differ significantly between the RADP and LDP groups. And concerning pathological outcomes, positive margin rate and the number of lymph nodules harvested were comparable between the two groups. The operative cost of RADP was almost double that of LDP (WMD = 2350.2 US dollars; 95%CI: 1165.62, 3534.78; P = 0.0001).Conclusion: RADP showed a slight technical advantage. But whether this benefit is worth twofold cost should be considered by patient's individuation. [ABSTRACT FROM AUTHOR]

The sandblasting-acid-etched (SLA) technique and hydroxyapatite (HA) deposition are the two methods widely used to improve surface characteristics of titanium implants. In the current study, a layer of HA was deposited on SLA-treated titanium (SLA-Ti) by a simple deposition method. The surface topography and surface roughness of SLA-Ti and HA-coated titanium (HA-Ti) were evaluated using scanning electron microscope (SEM) and atomic force microscope (AFM). Protein adsorption, osteoblast chemotaxis as well as osteoblast attachment on both Ti surfaces were additionally analyzed. The results show that SLA-Ti surface is covered with uniform, multiple micropores, whereas HA-Ti surface is covered with a large number of uniform microparticles under multiple microporous background. In comparison to SLA-Ti, the surface roughness of HA-Ti surface is lower. The protein adsorption on SLA-Ti and HA-Ti surfaces is generally even, and the chemotaxis of osteoblast have no differences. After 12 and 24 h of incubation, more osteoblasts are adhered to the HA-Ti surface and more osteoblast-osteoblast connection is observed on HA-Ti surface compared to SLA-Ti surface. These findings demonstrate that HA coating deposited on SLA-Ti surface improves SLA-Ti surface morphology and promotes osteoblast attachment in vitro . [ABSTRACT FROM AUTHOR]

In order to analyze the supersonic and transonic panel flutter behaviors quantitatively and accurately, a fluid-structure coupling algorithm based on the finite element method (FEM) is proposed to study the two-dimensional panel flutter problem. First, the Von Kármán's large deformation is used to model the panel, and the high speed airflow is approached by the Euler equations. Then, the equation of panel is discretized spatially by the standard Galerkin FEM, and the equations of fluid are discretized by the characteristic-based split finite element method (CBS-FEM) with dual time stepping; thus, the numerical oscillation encountered frequently in the numerical simulation of flow field could be removed efficiently. Further, a staggered algorithm is used to transfer the information on the inteiface between the fluid and the structure. Finally, the aeroelastic behaviors of the panel in both the supersonic and transonic airflows are studied in details. And the results show that the system can present the flat and stable, simple har-monic oscillation, buckling, and inharmonic oscillation states at Mach 2, considering the effect of the pretightening force; at Mach 1.2, as the panel loses stability, the ensuing limit cycle oscillation is born; at Mach 0.8 and 0.9, positive and negative bucklings are the typical states of the panel as it loses its stability. Further, the transonic stability boundaiy is obtained and the transonic bucket is precisely captured. More, this algorithm can be applied to the numerical analysis of other complicated problems related to aeroelasticity. [ABSTRACT FROM AUTHOR]

• An approach for urban landscape character assessment is proposed. • An urban landscape quantification system for urban built environment based on blocks is proposed. • The expansion of LCA in research scale, research unit, and research technology is realized. • The urban landscape character databases of 2 megacities are established. Diverse urban landscape is an important cultural driving force for urban sustainable development. Although characterizing landscape to protect landscape diversity is widely used in regional landscape and preservation practices, it is difficult to apply to urban landscape character assessment, which needs fine-scale data support, explicit study units, and effective clustering models. Therefore, this study uses urban big geospatial data and machine learning technology to establish a technical system for character assessment of urban landscape applicable to the block scale and complete the landscape assessment of urban areas of Beijing and Shanghai, China. A total of 64 landscape character types were identified in Beijing, and 61 in Shanghai. We find that (1) urban landscape characters are different with the ring road as the boundary, but each zone presents a combination of different proportions of landscape characters. (2) Beijing's city wall demolition policy is affected by historical protection policy. Landscape differentiation on both sides of the Huangpu River in Shanghai has yet to be realized. This study extends the theory of LCA and realizes the research exploration of urban built environment. It can also be used to guide urban zoning control, evaluate planning policy, and provide assistance in practice for sustainable urban development and management. [ABSTRACT FROM AUTHOR]

Introduction. While serendipity is gaining increasing attention in the context of information research these years, there is a lack of empirical evidence to demonstrate the nature of serendipity in literature. Method. We conducted a diary study with eleven participations to understand serendipity in information research. A mobile diary application was developed which allows participants to rapidly capture how serendipity happens in their daily life and the context in which they experience serendipity for one week. Their diary entries were discussed during post-study interviews. Analysis. An Emergent Themes Analysis was conducted to understand our data. Results. We identified: 1) some key elements to support understanding of serendipity, 2) the influential role of context in serendipitous experiences, 3) a framework of understanding how serendipity happens and 4) the positive impacts of serendipity in people's information research. Conclusions. Our research suggests that a framework for classifying serendipity should consider aspects associated with the activity, the value of the information, the source of the information and the interaction between the individual and the context. [ABSTRACT FROM AUTHOR]