MIX-crowds, an anonymity scheme for file retrieval systems

In this paper, we propose an anonymous scheme for file retrieval systems, MIX-Crowds, in which it is harder for an attacker to identify the requester of the file by making use of the idea of MIX [7] and Crowds [20] to establish a path from the requester to the file holder. Result shows that predecessor attack [26] is much more difficult to succeed compared with Crowds [20]. We are able to reduce the estimated number of rounds needed for successful predecessor attack for MIX-Crowds. We also propose a file transfer strategy according to file size. With such strategy, requests for small size files can be completed faster while the downloading time of large size files only increases slightly. © 2009 IEEE.published_or_final_versionThe 28th International Conference on Computer Communications (IEEE INFOCOM 2009), Rio de Janeiro, Brazil, 19-25 April 2009. In Proceedings of the IEEE Infocom, 2009, p. 1170-117

Enhanced distance-based location management of mobile communication systems using a cell coordinates approach

In managing the locations of mobile users in mobile communication systems, the distance-based strategy has been proven to have better performance than other dynamic strategies, but is difficult to implement. In this paper, a simple approach is introduced to implement the distance-based strategy by using the cell coordinates in calculating the physical distance traveled. This approach has the advantages of being independent of the size, shape, and distribution of cells, as well as catering for the direction of movement in addition to the speed of each mobile terminal. An enhanced distance-based location management strategy is proposed to dynamically adjust the size and shape of location area for each individual mobile terminal according to the current speed and direction of movement. It can reduce the location management signaling traffic of the distance-based strategy by half when mobile terminals have predictable directions of movement. Three types of location updating schemes are discussed, namely, Circular Location Area, Optimal Location Area, and Elliptic Location Area. Paging schemes using searching techniques such as expanding distance search based on the last reported location and based on the predicted location, and expanding direction search are also explored to further reduce paging signal traffic by partitioning location areas into paging areas.published_or_final_versio

Initial use of knowledge forum for Chinese students: Productive discourse and knowledge building

published_or_final_versionCentre for Information Technology in Education, University of Hong Kon

Decellularization of chondrocyte-encapsulated collagen microspheres: A three-dimensional model to study the effects of acellular matrix on stem cell fate

Extracellular matrix (ECM) partially constitutes the stem cell niche. Reconstituting the ECM niche in a three-dimensional (3D) configuration will significantly enhance our understanding of how stem cells interact with and respond to the ECM niche. In this study, we aimed to reconstitute a glycosaminoglycan (GAG)-rich ECM using a microencapsulation technology, produce acellular matrix using a decellularization technique, and investigate the effect of acellular matrix on stem cell fate by repopulating the matrix with human mesenchymal stem cells (hMSCs). We demonstrated that porcine chondrocytes were able to deposit a GAG-rich ECM within the 3D collagen microsphere. All decellularization treatment groups resulted in significant removal of chondrocyte nuclei, but acellular matrix was only achieved using 2% sodium deoxycholate. Nevertheless, decellularization resulted in significant loss in GAG content in almost all treatment groups, and the 2% sodium deoxycholate group was able to preserve about 40% of the GAGs compared with the control group. We further demonstrated that hMSCs seeded onto the decellularized microspheres were able to survive and penetrate into the centre, while hMSCs seeded in the acellular matrix showed positive immunostaining against sox9, indicating that they may be differentiating toward the chondrogenic lineage without the need to supplement the chondrogenic differentiation medium. © 2009 Mary Ann Liebert, Inc.published_or_final_versio

Atrial fibrillation: Prevention and termination with pacing

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

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Effect of ZnO surface defects on efficiency and stability of ZnO-based perovskite solar cells

ZnO as an alternative electron transport layer (ETL) material for perovskite solar cell applications has drawn increasing research interest due to its comparable energy levels to TiO2, relatively high electron mobility, as well as its feasibility to be processed at low temperatures for potential applications in flexible devices. Nevertheless, ZnO based perovskite devices usually exhibit inferior performance and severe stability drawbacks which are related to the surface defects of ZnO ETL. In this study, to investigate the correlation between ZnO defect composition and resulting device performance, different approaches of preparing ZnO ETL are compared in terms of the perovskite morphology and device performance. In addition, direct manipulations of ZnO surface defects are performed by various surface treatments, and the photovoltaic performance of devices with ZnO ETL subjected to different surface treatments is compared. Surface modification of ZnO ETL by ethanolamine (EA) is demonstrated to efficiently enhance the photovoltaic performance of resulting ZnO based devices. © (2017) COPYRIGHT Societypublished_or_final_versio

Nanomechanical measurement of adhesion and migration of leukemia cells with phorbol 12-myristate 13-acetate treatment

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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

Alternatives to colonoscopy for population-wide colorectal cancer screening

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