1,099 research outputs found
Who Contributes to the Knowledge Sharing Economy?
Information sharing dynamics of social networks rely on a small set of
influencers to effectively reach a large audience. Our recent results and
observations demonstrate that the shape and identity of this elite, especially
those contributing \emph{original} content, is difficult to predict.
Information acquisition is often cited as an example of a public good. However,
this emerging and powerful theory has yet to provably offer qualitative
insights on how specialization of users into active and passive participants
occurs.
This paper bridges, for the first time, the theory of public goods and the
analysis of diffusion in social media. We introduce a non-linear model of
\emph{perishable} public goods, leveraging new observations about sharing of
media sources. The primary contribution of this work is to show that
\emph{shelf time}, which characterizes the rate at which content get renewed,
is a critical factor in audience participation. Our model proves a fundamental
\emph{dichotomy} in information diffusion: While short-lived content has simple
and predictable diffusion, long-lived content has complex specialization. This
occurs even when all information seekers are \emph{ex ante} identical and could
be a contributing factor to the difficulty of predicting social network
participation and evolution.Comment: 15 pages in ACM Conference on Online Social Networks 201
Antiobesity and lipid-lowering effects of Bifidobacterium spp. in high fat diet-induced obese rats
<p>Abstract</p> <p>Background</p> <p>Recent studies have reported the preventive effects of probiotics on obesity. Among commensal bacteria, bifidobacteria is one of the most numerous probiotics in the mammalian gut and are a type of lactic acid bacteria. The aim of this study was to assess the antiobesity and lipid-lowering effects of <it>Bifidobacterium </it>spp. isolated from healthy Korean on high fat diet-induced obese rats.</p> <p>Methods</p> <p>Thirty-six male Sprague-Dawley rats were divided into three groups as follows: (1) SD group, fed standard diet; (2) HFD group, fed high fat diet; and (3) HFD-LAB group, fed high fat diet supplemented with LAB supplement (<it>B. pseudocatenulatum </it>SPM 1204, <it>B. longum </it>SPM 1205, and <it>B. longum </it>SPM 1207; 10<sup>8 </sup>~ 10<sup>9 </sup>CFU). After 7 weeks, the body, organ, and fat weights, food intake, blood serum levels, fecal LAB counts, and harmful enzyme activities were measured.</p> <p>Results</p> <p>Administration of LAB reduced body and fat weights, blood serum levels (TC, HDL-C, LDL-C, triglyceride, glucose, leptin, AST, ALT, and lipase levels), and harmful enzyme activities (β-glucosidase, β-glucuronidase, and tryptophanase), and significantly increased fecal LAB counts.</p> <p>Conclusion</p> <p>These data suggest that <it>Bifidobacterium </it>spp. used in this study may have beneficial antiobesity effects.</p
Depression and anxiety one month after stroke
Depression and anxiety after stroke negatively affect patient outcomes; however, health care professionals may overlook poststroke depression and anxiety while they focus on the physical disabilities of patients soon after a stroke. The purpose of this study was to investigate the prevalence and predictors of depression, anxiety, or both concurrently at one month after stroke. We conducted a cross-sectional, descriptive study in a sample of 231 hospitalized patients with ischemic stroke in Korea. Data were collected by interviews using a series of structured questionnaires in addition to clinical data retrieved from patients’ medical records. More than 70% were identified as depressed, 45.9% experienced anxiety, and 43.7% had concurrent depression and anxiety. Using a multiple logistic regression analysis, we identified anxiety as a predictor of depression; depression as a predictor of anxiety; and female sex, headaches, and swallowing difficulty as predictors of the comorbidity of depression and anxiety. Periodical screenings for poststroke depression and anxiety from an early stage in a hospital to years after stroke in a community are recommended to provide better chances for early identification of patients at risk because depression and anxiety may manifest at any stage of recovery. Special attention should be given to individuals with culture-bound somatic symptoms in addition to female patients and those who have difficulty swallowing among Korean stroke patients
White, Man, and Highly Followed: Gender and Race Inequalities in Twitter
Social media is considered a democratic space in which people connect and
interact with each other regardless of their gender, race, or any other
demographic factor. Despite numerous efforts that explore demographic factors
in social media, it is still unclear whether social media perpetuates old
inequalities from the offline world. In this paper, we attempt to identify
gender and race of Twitter users located in U.S. using advanced image
processing algorithms from Face++. Then, we investigate how different
demographic groups (i.e. male/female, Asian/Black/White) connect with other. We
quantify to what extent one group follow and interact with each other and the
extent to which these connections and interactions reflect in inequalities in
Twitter. Our analysis shows that users identified as White and male tend to
attain higher positions in Twitter, in terms of the number of followers and
number of times in user's lists. We hope our effort can stimulate the
development of new theories of demographic information in the online space.Comment: In Proceedings of the IEEE/WIC/ACM International Conference on Web
Intelligence (WI'17). Leipzig, Germany. August 201
Site-specific immobilization of microbes using carbon nanotubes and dielectrophoretic force for microfluidic applications
We developed a microbial immobilization method for successful applications in microfluidic devices. Single-walled nanotubes and Escherichia coli were aligned between two cantilever electrodes by a positive dielectrophoretic force resulting in a film of single-walled nanotubes with attached Escherichia coli. Because this film has a suspended and porous structure, it has a larger reaction area and higher reactant transfer efficiency than film attached to the substrate surface. The cell density of film was easily controlled by varying the cell concentration of the suspension and varying the electric field. The film showed excellent stability of enzyme activity, as demonstrated by measuring continuous reaction and long-term storage times using recombinant Escherichia coli that expressed organophosphorus hydrolase.X1133sciescopu
Promoter methylation and downregulation of SLC22A18 are associated with the development and progression of human glioma
<p>Abstract</p> <p>Background</p> <p>Downregulation of the putative tumor suppressor gene <it>SLC22A18 </it>has been reported in a number of human cancers. The aim of this study was to investigate the relationship between <it>SLC22A18 </it>downregulation, promoter methylation and the development and progression of human glioma.</p> <p>Method</p> <p><it>SLC22A18 </it>expression and promoter methylation was examined in human gliomas and the adjacent normal tissues. U251 glioma cells stably overexpressing <it>SLC22A18 </it>were generated to investigate the effect of <it>SLC22A18 </it>on cell growth and adherence <it>in vitro </it>using the methyl thiazole tetrazolium assay. Apoptosis was quantified using flow cytometry and the growth of <it>SLC22A18 </it>overexpressing U251 cells was measured in an <it>in viv</it>o xenograft model.</p> <p>Results</p> <p><it>SLC22A18 </it>protein expression is significantly decreased in human gliomas compared to the adjacent normal brain tissues. <it>SLC22A18 </it>protein expression is significantly lower in gliomas which recurred within six months after surgery than gliomas which did not recur within six months. <it>SLC22A18 </it>promoter methylation was detected in 50% of the gliomas, but not in the adjacent normal tissues of any patient. SLC22A18 expression was significantly decreased in gliomas with <it>SLC22A18 </it>promoter methylation, compared to gliomas without methylation. The <it>SLC22A18 </it>promoter is methylated in U251 cells and treatment with the demethylating agent 5-aza-2-deoxycytidine increased <it>SLC22A18 </it>expression and reduced cell proliferation. Stable overexpression of <it>SLC22A18 </it>inhibited growth and adherence, induced apoptosis <it>in vitro </it>and reduced <it>in vivo </it>tumor growth of U251 cells.</p> <p>Conclusion</p> <p><it>SLC22A18 </it>downregulation via promoter methylation is associated with the development and progression of glioma, suggesting that <it>SLC22A18 </it>is an important tumor suppressor in glioma.</p
Quantum dots for hybrid energy harvesting: from integration to piezo-phototronics
Energy harvesting, which converts wasted environmental energy into electricity by utilizing various physical effects, hasattracted tremendous research interests as is one of the key technologies to realize advanced electronics in the future. In this review, we introduce recent progress in the field of hybrid energy harvesting technology. In particular, we focus on a quantum dots (QD)‐based hybrid energy harvesting device. Attributed to fascinating material properties that QD possess, employment of QDs into hybrid energy harvesting has shown great potential for independent and sustainable energy supply.First, an integration of a QD solar cell into a mechanical energy harvester is discussed to harness different types of environmental energy sources simultaneously. Second, a comprehensive explanation of a piezotronic and piezo‐phototronic effect is provided, which is followed by QD‐based piezo‐phototronic applications. Finally, we summarize recent progress that has been made in energy harvesting technology involving a photovoltaic and piezo/triboelectric effec
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