A congestion-pricing problem with a polycentric region and multi-class users: a continuum modelling approach

postprin

Reducing the negative frame-of-reference effects on academic self-concept in academically selective schools

Research in diversified settings and cultures showed that academic selective schools might have negative effects on students academic self-concept. The big-fish-little-pond-effect (BFLPE) posits that the same student will have a lower academic self-concept in an academically selective school than in a nonselective school. Using two large data sets (the international PISA study with 103,558 students and 1950 Chinese students in Hong Kong), we examined a wide range of motivational (e.g., goals, interest, self-regulated learning) and individual background (e.g., socio-economic status, familial support) to see whether they would moderate the BFLPE. Though not very consistent and strong, we found some supports that students self concept would be less negatively affected if they had stronger mastery goal and lower avoidance goals.published_or_final_versio

Regression Towards the Mean Artifacts and Matthew Effects in multilevel analyses of value-added of individual schools

League tables are a problematic approach to inferring school effectiveness, but traditional value-added approaches are fraught with statistical complexities. According to the Regression Towards the Mean Artifacts (RTMA), students with initially high or low scores tend to regress towards the mean in subsequent testing, resulting in biased estimates of school growth (Marsh & Hau, 2002). The Matthews Effect is an apparently counter-balancing artifact in growth in achievement gains is systematically larger for students who are initially more able. (i.e., the rich becomes richer). Mathematical proof shows that although the Matthew and the RTMA artifacts work in opposite direction and tend to cancel each other, they share a similar mechanism and can be rectified. In this study, mathematical derivations and Monte Carlo simulated data are used to compare four models, namely: (i) without any remedy, (ii) with remedy for Matthew effect only, (iii) with remedy for RTMA only, (iv) remedies for both Matthew and RTMA effects. The conditional strategy with individual assignment test scores (used in assigning students to different schools) as covariate remedies artifacts, consistent with Marsh & Hau's (2002) conclusion for RTMA. The associated problems with the two effects in estimating school value-added information are discussed.published_or_final_versio

A Continuum Model for Housing Allocation and Transportation Emission Problems in a Polycentric City

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Recurrent acute heart failure caused by sliding hiatus hernia

The case is reported of a 75 year old woman who presented with recurrent nocturnal episodes of acute pulmonary oedema. The cause was uncertain as she had normal cardiothoracic ratio on chest radiography and normal left ventricular systolic and diastolic function by transthoracic echocardiogram. Another transthoracic echocardiogram was repeated when she was recumbent for an hour and had a full stomach. It showed a striking finding of severe left atrial compression by an external structure. Computed tomography of the thorax showed an intrathoracic mass behind the left atrium causing external compression of the left atrium suggestive of a sliding hiatus hernia. Cardiac catheterisation confirmed the diagnosis by showing a pronounced rise of pulmonary capillary wedge pressure in the recumbent position compared with the sitting up position.published_or_final_versio

Identification of a novel bat papillomavirus by metagenomics

published_or_final_versio

The effect of qigong on depressive and anxiety symptoms: a systematic review and meta-analysis of randomized controlled trials

published_or_final_versio

Spiral Arms, Infall, and Misalignment of the Circumbinary Disk from the Circumstellar Disks in the Protostellar Binary System L1551 NE

postprin

Infall of gas as the formation mechanism of stars up to 20 times more massive than the Sun

Theory predicts and observations confirm that low-mass stars (like the Sun) in their early life grow by accreting gas from the surrounding material. But for stars ~ 10 times more massive than the Sun (~10 M_sun), the powerful stellar radiation is expected to inhibit accretion and thus limit the growth of their mass. Clearly, stars with masses >10 M_sun exist, so there must be a way for them to form. The problem may be solved by non-spherical accretion, which allows some of the stellar photons to escape along the symmetry axis where the density is lower. The recent detection of rotating disks and toroids around very young massive stars has lent support to the idea that high-mass (> 8 M_sun) stars could form in this way. Here we report observations of an ammonia line towards a high-mass star forming region. We conclude from the data that the gas is falling inwards towards a very young star of ~20 M_sun, in line with theoretical predictions of non-spherical accretion.Comment: 11 pages, 2 figure