Understanding Users’ Continuance Intention to Answer Questions in Online Question Answering Communities

This study develops a research model to investigate the antecedents of users’ continuance intention to answer questions in online question answering (Q&A) communities based on the literature of knowledge contribution and behavioral continuance. The research model is tested by using the data collected from 241 users of a famous online Q&A community in China (i.e., “Yahoo! Answers China”). The results indicate that satisfaction is the key determinant of continuance intention to answer questions. Satisfaction is, in turn, influenced by reputation enhancement, enjoyment in helping others and advancement of the online community. This study has implications for both theory and practice on the management and design of online Q&A communities

Inter-plane artifact suppression in tomosynthesis using 3D CT image data

<p>Abstract</p> <p>Background</p> <p>Despite its superb lateral resolution, flat-panel-detector (FPD) based tomosynthesis suffers from low contrast and inter-plane artifacts caused by incomplete cancellation of the projection components stemming from outside the focal plane. The incomplete cancellation of the projection components, mostly due to the limited scan angle in the conventional tomosynthesis scan geometry, often makes the image contrast too low to differentiate the malignant tissues from the background tissues with confidence.</p> <p>Methods</p> <p>In this paper, we propose a new method to suppress the inter-plane artifacts in FPD-based tomosynthesis. If 3D whole volume CT images are available before the tomosynthesis scan, the CT image data can be incorporated into the tomosynthesis image reconstruction to suppress the inter-plane artifacts, hence, improving the image contrast. In the proposed technique, the projection components stemming from outside the region-of-interest (ROI) are subtracted from the measured tomosynthesis projection data to suppress the inter-plane artifacts. The projection components stemming from outside the ROI are calculated from the 3D whole volume CT images which usually have lower lateral resolution than the tomosynthesis images. The tomosynthesis images are reconstructed from the subtracted projection data which account for the x-ray attenuation through the ROI. After verifying the proposed method by simulation, we have performed both CT scan and tomosynthesis scan on a phantom and a sacrificed rat using a FPD-based micro-CT.</p> <p>Results</p> <p>We have measured contrast-to-noise ratio (CNR) from the tomosynthesis images which is an indicator of the residual inter-plane artifacts on the focal-plane image. In both cases of the simulation and experimental imaging studies of the contrast evaluating phantom, CNRs have been significantly improved by the proposed method. In the rat imaging also, we have observed better visual contrast from the tomosynthesis images reconstructed by the proposed method.</p> <p>Conclusions</p> <p>The proposed tomosynthesis technique can improve image contrast with aids of 3D whole volume CT images. Even though local tomosynthesis needs extra 3D CT scanning, it may find clinical applications in special situations in which extra 3D CT scan is already available or allowed.</p

Controllable modification of transport properties of single-walled carbon nanotube field effect transistors with in situ Al decoration

We use an in situ Al decoration technique to control the transport characteristics of single-walled carbon nanotube field effect transistors (SWNT-FETs). Al nanoparticle decoration in a high vacuum caused the devices to change from p -type to n -type FETs, and subsequent exposure to the ambient atmosphere induced a gradual recovery of p -type character. In comparison with the bare SWNT-FETs under high vacuum, the channel-open devices with decorated Al particles exhibited reduced current under ambient conditions. However, selective Al decoration only at the contact resulted in an improved p -type current in ambient air.open182

Subspecific Status of the Korean Tiger Inferred by Ancient DNA Analysis

The tiger population that once inhabited the Korean peninsula was initially considered a unique subspecies (Panthera tigris coreensis), distinct from the Amur tiger of the Russian Far East (P. t. altaica). However, in the following decades, the population of P. t. coreensis was classified as P. t. altaica and hence forth the two populations have been considered the same subspecies. From an ecological point of view, the classification of the Korean tiger population as P. t. altaica is a plausible conclusion. Historically, there were no major dispersal barriers between the Korean peninsula and the habitat of Amur tigers in Far Eastern Russia and northeastern China that might prevent gene flow, especially for a large carnivore with long-distance dispersal abilities. However, there has yet to be a genetic study to confirm the subspecific status of the Korean tiger. Bone samples from four tigers originally caught in the Korean peninsula were collected from two museums in Japan and the United States. Eight mitochondrial gene fragments were sequenced and compared to previously published tiger subspecies\u27 mtDNA sequences to assess the phylogenetic relationship of the Korean tiger. Three individuals shared an identical haplotype with the Amur tigers. One specimen grouped with Malayan tigers, perhaps due to misidentification or mislabeling of the sample. Our results support the conclusion that the Korean tiger should be classified as P. t. altaica, which has important implications for the conservation and reintroduction of Korean tigers

Instability of a two-dimensional extremal black hole

We consider the perturbation of tachyon about the extremal ground state of a two-dimensional (2D) electrically charged black hole. It is found that the presenting potential to on-coming tachyonic wave takes a double-humped barrier well. This allows an exponentially growing mode with respect to time. This extremal ground state is classically unstable. We conclude that the 2D extremal electrically charged black hole cannot be a candidate for the stable endpoint of the Hawking evaporation.Comment: 9 pages 2 figures, RevTeX, to be published in Phys. Rev D, to obtain gifures contact Author ([email protected]

Impacts of African swine fever on water quality in China

The outbreak of African swine fever (ASF) in China has significantly reduced the country’s pig production capability, whilst also having far-reaching impacts on livestock products supply in the wider food system. Previous studies have quantified the potential long-terms impacts on food prices, however, little information is available regarding the direct short-term impacts on food system changes (livestock products supply and consumption patterns) and water quality protection associated with the outbreak. Here, we used multiple sources of data in relation to consumption patterns and water quality to fill this knowledge gap. Our results indicate that the ASF outbreak has changed the short-term livestock products consumption pattern in China, with increasing reliance on importation of livestock products. A rapid change in pork self-sufficiency rate has also driven a rapid increase in the consumer price index of many cities. Banned swill feeding and reversed environmental regulations in the watercourse intense regions has unintended consequences, especially on water quality. Swill, which is no longer fed, was dumped into water waste streams and lowered the sewage treatment efficiency. The re-establishment of pig production back into watercourse intense regions has led to exceedance of local manure nutrient loading capacity of agricultural land. We suggest (a) a short-term intermediate policy to prohibit discharge of swill to sewage systems, to return their previous efficiency, (b) the development of new technologies for the safe recycling of swills, and (c) the design of a long-term intelligent spatial planning of pig production, slaughter and transportation within China to ensure continued protection of water quality vulnerable zones