On Refining Twitter Lists as Ground Truth Data for Multi-Community User Classification

To help scholars and businesses understand and analyse Twitter users, it is useful to have classifiers that can identify the communities that a given user belongs to, e.g. business or politics. Obtaining high quality training data is an important step towards producing an effective multi-community classifier. An efficient approach for creating such ground truth data is to extract users from existing public Twitter lists, where those lists represent different communities, e.g. a list of journalists. However, ground truth datasets obtained using such lists can be noisy, since not all users that belong to a community are good training examples for that community. In this paper, we conduct a thorough failure analysis of a ground truth dataset generated using Twitter lists. We discuss how some categories of users collected from these Twitter public lists could negatively affect the classification performance and therefore should not be used for training. Through experiments with 3 classifiers and 5 communities, we show that removing ambiguous users based on their tweets and profile can indeed result in a 10% increase in F1 performance

A Comparative analysis of mice destinations between Macau and Singapore

Macau is probably best known worldwide for its gaming industry which has always been a staple of its economy and has surpassed Las Vegas as the world’s biggest gambling market in 2006 (Cheung, 2007). After its return to Chinese rule in 1999, the Macau Special Administrative Region (SAR) government decided to diversify its economy and liberalized the gaming market with an aim to transform the territory into a centre of gaming, cultural events, conference and exhibition (Pao, 2004). Recognizing the economic benefits of MICE, the SAR government aims to nurture the city into a prominent MICE destination (Macau Government Tourist Office [MGTO], 2002, 2006). In less than a decade, Macau’s MICE and gaming industries have developed tremendously, driven by enormous integrated entertainment projects funded by huge amounts of investment capital from players like MGM Mirage, Wynn Resorts and Las Vegas Sands. Its profile was further lifted internationally with the opening of The Venetian Macao Resort Hotel, sister property of the iconic The Venetian Las Vegas. In 2006, Macau organized 18% more international events than the previous year, lifting the total to 360 with 57,000 participants. This is a good 43% increase when compared to 2001 (MGTO, 2002, 2007a, 2007b). In the same year, Macau was ranked 107 by the Amsterdam-based International Congress and Convention Association’s (ICCA) City Rankings. According to ICCA, Macau organized 11 meetings in 2006, more than doubled the 5 meetings organized in 2005 (ICCA, 2007)

Discrete Imaging Models for Three-Dimensional Optoacoustic Tomography using Radially Symmetric Expansion Functions

Optoacoustic tomography (OAT), also known as photoacoustic tomography, is an emerging computed biomedical imaging modality that exploits optical contrast and ultrasonic detection principles. Iterative image reconstruction algorithms that are based on discrete imaging models are actively being developed for OAT due to their ability to improve image quality by incorporating accurate models of the imaging physics, instrument response, and measurement noise. In this work, we investigate the use of discrete imaging models based on Kaiser-Bessel window functions for iterative image reconstruction in OAT. A closed-form expression for the pressure produced by a Kaiser-Bessel function is calculated, which facilitates accurate computation of the system matrix. Computer-simulation and experimental studies are employed to demonstrate the potential advantages of Kaiser-Bessel function-based iterative image reconstruction in OAT

Persistent Biomechanical Alterations After ACL Reconstruction Are Associated With Early Cartilage Matrix Changes Detected by Quantitative MR.

BackgroundThe effectiveness of anterior cruciate ligament (ACL) reconstruction in preventing early osteoarthritis is debated. Restoring the original biomechanics may potentially prevent degeneration, but apparent pathomechanisms have yet to be described. Newer quantitative magnetic resonance (qMR) imaging techniques, specifically T1ρ and T2, offer novel, noninvasive methods of visualizing and quantifying early cartilage degeneration.PurposeTo determine the tibiofemoral biomechanical alterations before and after ACL reconstruction using magnetic resonance imaging (MRI) and to evaluate the association between biomechanics and cartilage degeneration using T1ρ and T2.Study designCohort study; Level of evidence, 2.MethodsKnee MRIs of 51 individuals (mean age, 29.5 ± 8.4 years) with unilateral ACL injuries were obtained prior to surgery; 19 control subjects (mean age, 30.7 ± 5.3 years) were also scanned. Follow-up MRIs were obtained at 6 months and 1 year. Tibial position (TP), internal tibial rotation (ITR), and T1ρ and T2 were calculated using an in-house Matlab program. Student t tests, repeated measures, and regression models were used to compare differences between injured and uninjured sides, observe longitudinal changes, and evaluate correlations between TP, ITR, and T1ρ and T2.ResultsTP was significantly more anterior on the injured side at all time points (P < .001). ITR was significantly increased on the injured side prior to surgery (P = .033). At 1 year, a more anterior TP was associated with elevated T1ρ (P = .002) and T2 (P = .026) in the posterolateral tibia and with decreased T2 in the central lateral femur (P = .048); ITR was associated with increased T1ρ in the posteromedial femur (P = .009). ITR at 6 months was associated with increased T1ρ at 1 year in the posteromedial tibia (P = .029).ConclusionPersistent biomechanical alterations after ACL reconstruction are related to significant changes in cartilage T1ρ and T2 at 1 year postreconstruction. Longitudinal correlations between ITR and T1ρ suggest that these alterations may be indicative of future cartilage injury, leading to degeneration and osteoarthritis.Clinical relevanceNewer surgical techniques should be developed to eliminate the persistent anterior tibial translation commonly seen after ACL reconstruction. qMR will be a useful tool to evaluate the ability of these newer techniques to prevent cartilage changes

Dust formation, evolution, and obscuration effects in the very high-redshift universe

The evolution of dust at redshifts z>9, and consequently the dust properties, differs greatly from that in the local universe. In contrast to the local universe, core collapse supernovae (CCSNe) are the only source of thermally-condensed dust. Because of the low initial dust-to-gas mass ratio, grain destruction rates are low, so that CCSNe are net producers of interstellar dust. Galaxies with large initial gas mass or high mass infall rate will therefore have a more rapid net rate of dust production comported to galaxies with lower gas mass, even at the same star formation rate. The dust composition is dominated by silicates, which exhibit a strong rise in the UV opacity near the Lyman break. This "silicate-UV break" may be confused with the Lyman break, resulting in a misidentification of a galaxies' photometric redshift. In this paper we demonstrate these effects by analyzing the spectral energy distribution (SED) of MACS1149-JD, a lensed galaxy at z=9.6. A potential 2mm counterpart of MACS1149-JD has been identified with GISMO. While additional observations are required to corroborate this identification, we use this possible association to illustrate the physical processes and the observational effects of dust in the very high redshift universe.Comment: Accepted for publication in ApJ Letter

A Comparison of Contemporary Filial Piety in Rural and Non-Rural China and Taiwan

Research has found that filial piety remains strong in Chinese societies, despite dramatic social and economic changes. However, little is known about differences in filial piety between rural and nonrural regions of China and Taiwan, as well as gender differences in filial piety. Using data from the 2006 East Asia Social Survey, results indicated that there were no differences in attitudes about filial piety and attitudes of financial support between rural and nonrural regions in China and Taiwan, as well between adult men and women. Caregiving for elderly parents was more common in rural China, compared to nonrural China, and men in rural China were more likely to be engaged than rural women in caregiving. There were no other differences in reports of caregiving. Overall, the results suggest a lessening of gender differences and rural vs. nonrural differences in filial piety in China and Taiwan