Location extraction from tweets Hoang, Thi Bich Ngoc; Mothe, Josiane
Information processing & management,
March 2018, 2018-03-00, 20180301, 2018-03, Letnik:
54, Številka:
2
Journal Article
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Five hundred million tweets are posted daily, making Twitter a major social media platform from which topical information on events can be extracted. These events are represented by three main ...dimensions: time, location and entity-related information. The focus of this paper is location, which is an essential dimension for geo-spatial applications, either when helping rescue operations during a disaster or when used for contextual recommendations. While the first type of application needs high recall, the second is more precision-oriented. This paper studies the recall/precision trade-off, combining different methods to extract locations. In the context of short posts, applying tools that have been developed for natural language is not sufficient given the nature of tweets which are generally too short to be linguistically correct. Also bearing in mind the high number of posts that need to be handled, we hypothesize that predicting whether a post contains a location or not could make the location extractors more focused and thus more effective. We introduce a model to predict whether a tweet contains a location or not and show that location prediction is a useful pre-processing step for location extraction. We define a number of new tweet features and we conduct an intensive evaluation. Our findings are that (1) combining existing location extraction tools is effective for precision-oriented or recall-oriented results, (2) enriching tweet representation is effective for predicting whether a tweet contains a location or not, (3) words appearing in a geography gazetteer and the occurrence of a preposition just before a proper noun are the two most important features for predicting the occurrence of a location in tweets, and (4) the accuracy of location extraction improves when it is possible to predict that there is a location in a tweet.
A second cluster of COVID-19 cases imported from Europe occured in Vietnam from early March 2020. We describe 44 SARS-CoV-2 RT-PCR positive patients (cycle threshold value <30) admitted to the ...National Hospital for Tropical Diseases in Hanoi between March 6 and April 15 2020. Whole SARS-CoV-2 genomes from these patients were sequenced using Illumina Miseq and analysed for common genetic variants and relationships to local and globally circulating strains. Results showed that 32 cases were Vietnamese with a median age of 37 years (range 15-74 years), and 23 were male. Most cases were acquired outside Vietnam, mainly from the UK (n = 15), other European countries (n = 14), Russia (n = 6) and countries in Asia (n = 3). No cases had travelled from China. Forty-one cases had symptoms at admission, typically dry cough (n = 36), fever (n = 20), sore throat (n = 14) and diarrhoea (n = 12). Hospitalisation was long with a median of 25 days, most commonly from 20-29 days. All SARS-CoV-2 genomes were similar (92-100% sequence homology) to the reference sequence Wuhan_1 (NC_045512), and 32 strains belonged to the B.1.1 lineage. The three most common variants were linked, and included C3037T, C14408T (nsp12: P323L) and A23403G (S: D614G) mutations. This group of mutations often accompanied variant C241T (39/44 genomes) or GGG 28881..28883 AAC (33/44 genomes). The prevalence of the former reflected probable European origin of viruses, and the transition D614G was dominant in Vietnam. New variants were identified; however, none could be associated with disease severity.
Studies of successive vaccination suggest that immunological memory against past influenza viruses may limit responses to vaccines containing current strains. The impact of memory induced by prior ...infection is rarely considered and is difficult to ascertain, because infections are often subclinical. This study investigated influenza vaccination among adults from the Ha Nam cohort (Vietnam), who were purposefully selected to include 72 with and 28 without documented influenza A(H3N2) infection during the preceding 9 years (Australian New Zealand Clinical Trials Registry 12621000110886). The primary outcome was the effect of prior influenza A(H3N2) infection on hemagglutinin-inhibiting antibody responses induced by a locally available influenza vaccine administered in November 2016. Baseline and postvaccination sera were titrated against 40 influenza A(H3N2) strains spanning 1968-2018. At each time point (baseline, day 14 and day 280), geometric mean antibody titers against 2008-2018 strains were higher among participants with recent infection (34 (29-40), 187 (154-227) and 86 (72-103)) than among participants without recent infection (19 (17-22), 91 (64-130) and 38 (30-49)). On days 14 and 280, mean titer rises against 2014-2018 strains were 6.1-fold (5.0- to 7.4-fold) and 2.6-fold (2.2- to 3.1-fold) for participants with recent infection versus 4.8-fold (3.5- to 6.7-fold) and 1.9-fold (1.5- to 2.3-fold) for those without. One of 72 vaccinees with recent infection versus 4 of 28 without developed symptomatic A(H3N2) infection in the season after vaccination (P = 0.021). The range of A(H3N2) viruses recognized by vaccine-induced antibodies was associated with the prior infection strain. These results suggest that recall of immunological memory induced by prior infection enhances antibody responses to inactivated influenza vaccine and is important to attain protective antibody titers.
•Predicting the retweetability and retweet rate of a given tweet.•An analysis of important predictive features is proposed.•Number of followers, groups that a user belongs strongly correlate with ...retweet number.
Information propagation on online social network focuses much attention in various domains as varied as politics, fact checking, or marketing. Modeling information diffusion in such growing communication media is crucial in order both to understand information propagation and to better control it. Our research aims at predicting whether a post is going to be forwarded or not. Moreover, we aim at predicting how much it is going to be diffused. Our model is based on three types of features: user-based, time-based and content-based. Using three collections corresponding to a total of about 16 millions of tweets, we show that our model improves of about 5% F-measure compared to the state of the art, both when predicting if a tweet is going to be re-tweeted and when predicting how popular it will be. F-measure in our model is between 70% and 82%, depending on the collection. We also show that some features we introduced are very important to predict retweetability such as the numbers of followers and number of communities that a user belongs to. Our contribution in this paper is twofold: firstly we defined new features to represent tweets in order to predict their possible propagation; secondly we evaluate the model we built on top of both features from the literature and features we defined on three collections and show the usefulness of our features in the prediction.
This is the first time in Vietnam that people have undergone “social distancing” to minimize the spreading of infectious disease, COVID-19. These deliberate preemptive strategies may have profound ...impacts on the mental health of the population. Therefore, this study aimed to identify the psychological impacts of COVID-19 on Vietnamese people and associated factors. We conducted a cross-sectional study during a one-week social distancing and isolation from April 7 to 14, 2020, in Vietnam. A snowball sampling technique was carried out to recruit participants. Impact of Event Scale-Revised (IES-R) was utilized to assess the psychological impacts of the COVID-19. Of all participants, 233 (16.4%) reported low level of PTSS; 76 (5.3%) rated as moderate, and 77 (5.4%) reported extreme psychological conditions. Being female, above 44 years old, or having a higher number of children in the family were positively associated with a higher level of psychological distress. Being self-employed/unemployed/retired was associated with a higher score of intrusion and hyperarousal subscale. Individuals who have a history of touching objects with the possibility of spreading coronavirus (utensils) were related to a higher level of avoidance. There were relatively high rates of participants suffering from PTSS during the first national lockdown related to COVID-19. Comprehensive strategies for the screen of psychological problems and to support high-risk groups are critical, especially females, middle-aged adults and the elderly, affected laborers, and health care professionals.
Online social network is a major media for many types of information communication. Although the primary purpose of social networks is to connect people, they are more and more used in online ...marketing to connect businesses with customers as well as to connect customers amongst themselves. Brand stories generated by consumers or businesses can be easily and widely spread. As a result, those stories have a huge influence on the marketplace and indirectly affect the brand success. Understanding and modeling how a piece of information is spread on social media and its spreading level are crucial for business managers; not only to understand the information diffusion, but also for them to better control it. In this paper, we aim at developing models in order to predict the spread of brand stories on social networks, both in term of spreadability and spreading level. We applied several machine learning algorithms using three categories of features based on user-profile, temporal, and content of tweets. Experimental results on three tweet collections about brand stories reveal that our model significantly improves the prediction accuracy by about 4% compared to the related work.
Evaluation of liver fibrosis is necessary to make the therapeutic decision and assess the prognosis of CHB patients. The current study aimed to describe the progression and identify some influencing ...factors in patients with chronic hepatitis B at a General Hospital in Northern Vietnam. The longitudinal study included 55 eligible subjects diagnosed Hepatitis-B-virus. Dependent variable was the aspartate aminotransferase/platelet ratio index and we collected some demographic variables and disease related and behaviour variables. Bayesian Model Averaging was used to select variables into model. Mixed-effect linear models were used to evaluate the change of the aspartate aminotransferase/platelet ratio index over time and identify related factors. the aspartate aminotransferase/platelet ratio index differences between examinations, age of participants, working status were statistically significant. This pattern indicated that the average the aspartate aminotransferase/platelet ratio index of the population decreased by 0.005 (95% CI=-0.009; -0.001) after each patient's visit, and increased by 0.013 if the patient's age increased by 1 year (95% CI=0.005; 0.0219). For non-working patients, the aspartate aminotransferase/platelet ratio index was lower, coefficient was -0.054 (95% CI=-0.108; 0.001). Other variables such as gender, education level, time for disease detection, drinking tea, alcohol consumption, forgetting to take medicine and the aspartate aminotransferase/platelet ratio index were not significantly different. The study showed that the majority of study subjects had average the aspartate aminotransferase/platelet ratio index, and were relatively well controlled and treated during the study. Age and working status are factors that influence the the aspartate aminotransferase/platelet ratio index.
Kurz is widely used in folk medicine in Eastern Asia and is associated with various ethnopharmacological properties including hepatoprotective, antipyretic, analgesic, antidysenteric, and ...anthelmintic activities. Previous phytochemical investigations reported the presence of numerous triterpenes (mostly cycloartanes, ursanes, lupanes, and oleananes) along with dozens of flavonoids. However, the extracts of
and isolated flavonoids have not been evaluated for their alpha-glucosidase inhibition. In the frame of our efforts dedicated to the chemical investigation of Vietnamese medicinal plants and their biological activities, a phytochemical study of the MeOH extract of the leaves of
using bioactive guided isolation was undertaken. In this paper, the isolation and structure elucidation of twelve known compounds, 5-hydroxy-3,7,4'-trimethoxyflavone (
), ayanin (
), kumatakenin (
), rhamnocitrin (
), ombuin (
), myricetin-3,7,3',5'-tetramethyl ether (
), gardenin D (
), luteolin (
), apigenin (
), mearnsetin (
), isoorientin (
), and vitexin (
) were reported. Bromination was applied to compounds
and
to provide four new synthetic analogues
-
. All isolated and synthesized compounds were evaluated for alpha-glucosidase inhibition and antibacterial activity. Compounds
and
showed moderate antibacterial activity against methicillin-resistant
while others were inactive. All compounds failed to reveal any activity toward extended spectrum beta-lactamase-producing
. Compounds
,
,
-
, and
-
showed good alpha-glucosidase inhibition with IC
values in the range of 30.5-282.0 µM. The kinetic of enzyme inhibition showed that
and
were noncompetitive type inhibition against alpha-glucosidase. In silico molecular docking model indicated that compounds
and
were potential inhibitors against enzyme
-glucosidase.
Purpose: Developmental language disorder (DLD), defined by low language performance despite otherwise normal development, can negatively impact children's social and academic outcomes. This study is ...the 1st to examine DLD in Vietnamese. To lay the foundation, we identified cases of DLD in Vietnam and explored language-specific characteristics of the disorder. Method: Teacher ratings of 1,250 kindergarteners living in Hanoi, Vietnam, were used to recruit children with and without risk for DLD. One hundred four children completed direct measures of vocabulary and language sampling, and their parents completed in-depth surveys. We examined convergence and divergence across tasks to identify measures that could serve as reliable indicators of risk. Then, we compared performance on direct language measures across ability levels. Results: There were positive associations between teacher and parent report and between report and direct language measures. Three groups were identified based on convergence across measures: DLD, some risk for DLD, and no risk. The DLD group performed lowest on measures of receptive and expressive vocabulary, mean length of utterance, and grammaticality. Although children with DLD exhibited a greater number of errors, the types of errors found were similar across DLD and No Risk groups. Conclusions: Similar to rates found globally, 7% of the kindergarten population in Vietnam exhibited risk for DLD. Results highlight the importance of parent and teacher report and the value of multiple measures to identify DLD. We discuss potential clinical markers for DLD in the Vietnamese language and outline future directions.
The present study aimed to evaluate the effectiveness of using platelet-rich fibrin (PRF) as the apical matrix for the placement of MTA in nonsurgical endodontic therapy for teeth with periapical ...lesions and open apices.
Twelve teeth from eleven patients with periapical periodontitis and open apices were enrolled in the study. Nonsurgical endodontic therapy was performed with the PRF used as an apical barrier and the MTA manipulated as an apical plug for further thermoplasticized gutta percha in the remaining part of the root canal. Clinical signs and periapical digital radiographs were recorded and analyzed to evaluate the curing progress after periodical follow-ups of 1, 3, and 6 months. The horizontal dimension of the periapical lesion was determined, and the changes in the dimensions were recorded each time. The Friedman test was used for statistical analysis, with P < .05 serving as the threshold for determining statistical significance.
All patients had no clinical symptoms after the first month of treatment, with a significant reduction in the periapical lesion after periodical appointments.
PRF is an effective barrier when combined with MTA for the treatment of teeth with periapical periodontitis and open apices.
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