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Search Results: 1 - 10 of 3462 matches for " Kin-Hang Kok "
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siRNA and shRNA screens advance key understanding of host factors required for HIV-1 replication
Kin-Hang Kok, Ting Lei, Dong-Yan Jin
Retrovirology , 2009, DOI: 10.1186/1742-4690-6-78
Abstract: The advent of RNAi-based whole-genome screens in mammalian cells provides a new impetus to the search of host cell factors needed for HIV replication [1,2]. Three screens that used siRNA pools to identify cellular proteins important in HIV-1 replication were reported in 2008, and a meta-analysis of these studies has been published recently [3-6]. One shortcoming to these reported screens is the use of HeLa or HEK293T cells that are not physiological substrates for infection by HIV-1. In addition, the use of a pseudotyped virus or a mutated strain of HIV-1 also limits the interpretability of some of the results. With this backdrop, a recently published genome-wide shRNA-screening performed in Jurkat T lymphocytes for cellular genes that contribute to HIV-1 replication (Figure 1) advances the field by extending the functional screening for cellular factors from attached epithelial/fibroblast cells to suspension T-cells [7].In the shRNA loss-of-function screen, Jurkat cells are transduced with a lentiviral vector-based shRNA library. The lentivector is derived from feline immunodeficiency virus and is pseudotyped with the vesicular stomatitis virus G protein. A major advantage that makes this scheme attractive is its potential application to cells that can be physiologically infected by HIV-1, including primary T cells and macrophages. In addition, it is noteworthy that the transduced Jurkat cells have been selected for shRNA-expression for extended duration before being subject to HIV-1 infection. This pre-infection selection for shRNA-expression serves to eliminate those shRNA-cell clones which are silenced for a gene whose knock down dramatically affects cell growth or survival. The pre-selection procedure thus significantly reduces the number of false positive genes identified in the screening. Unlike siRNAs, the activity of shRNAs in the cell is not transient, but is long-lasting. Because shRNAs are stably expressed, infection of cell clones with HIV-1 can be init
CREB3 subfamily transcription factors are not created equal: Recent insights from global analyses and animal models
Chi-Ping Chan, Kin-Hang Kok, Dong-Yan Jin
Cell & Bioscience , 2011, DOI: 10.1186/2045-3701-1-6
Abstract: The CREB3 subfamily of bZIP transcription factors in mammals comprises CREB3 (also known as LZIP or Luman), CREB3L1 (OASIS), CREB3L2 (BBF2H7), CREB3L3 (CREB-H) and CREB3L4 (AIbZIP) [1]. CREB3, the prototype of this subfamily, was first identified through its interaction with a transcriptional coactivator termed host cell factor 1 (HCF1) [2]. CREB3L1 was initially found in long-term cultured mouse astrocytes and thought to have a role in gliotic events [3]. CREB3L2 was identified as part of a fusion oncoprotein named FUS-CREB3L2, which was generated by a chromosomal translocation in low grade fibromyxoid sarcoma (LGFMS) [4]. For CREB3L3, it was first reported to be a liver-specific transcription factor [5]. CREB3L4 was originally identified as a highly expressed and androgen-induced protein in prostate cancer cells [6]. The CREB3 subfamily members are closely-related to Drosophila dCREB-A/BBF2 [7,8]. They share significant homology within their bZIP domain that mediates DNA-binding and dimerization [9]. Similar to ATF6, they also feature a transmembrane domain at the immediate C-terminal side of the bZIP region (Figure 1) [1,10]. As such, they are type II membrane-associated proteins with the N-terminus facing the cytoplasm and the C-terminus penetrating through the endoplasmic reticulum (ER) membrane into the ER lumen [11,12]. Based on their structural similarity to ATF6, transcription factors of the CREB3 subfamily are thought to be activated through regulated intramembrane proteolysis (RIP) in response to ER stress [12]. Upon activation, they are transported from the ER to the Golgi apparatus and proteolytically cleaved there by site 1 protease (S1P) and S2P sequentially to release the N-terminal fragment, which translocates into the nucleus to activate the transcription of genes that play important roles in unfolded protein response (UPR) [12,13]. This model is generally applicable to ATF6 and all CREB3 subfamily transcription factors (Figure 2). In this model, t
‘One Health’ for the people of Hong Kong and the world
Kin-Hang Kok,Hei-Man Vincent Tang,Dong-Yan Jin
Science China Life Sciences , 2013, DOI: 10.1007/s11427-012-4408-6
Analysis of Statistical Content in Junior High School Mathematics Textbooks Based on Statistical Cognition and Graph Comprehension
Kin-Hang Lei,Kai-Lin Yang
Journal of Textbook Research , 2012,
Abstract: Content analysis was used to investigate statistical cognition and graph com-prehension of two textbooks edited according to 2003 curriculum guidelines. We found that the two textbooks provide substantial learning opportunities for statistical literacy; however, they provide almost no learning opportunities for statistical reasoning and thinking. Furthermore, both of the textbooks provide learning opportunities to interpret graphs by recognizing components and in-formation displayed in graphs, but provide almost no learning opportunities to infer from graphs or choose proper graphs for different situations. This may be because the guidelines only focus on knowing statistical knowledge, drawing graphs, and retrieving information directly. To enhance the ability of students to apply statistical graphs and concepts for making inferences, it is recommended to provide students with tasks for reasoning and thinking statistically, selecting graphs and making inference by analyzing information of graphs.
Numerical Modeling and Control of Rotating Plate with Coupled Self-Sensing and Frequency-Dependent Active Constrained Layer Damping
Zhengchao Xie,Pak Kin Wong,Long Zhang,Hang Cheong Wong
Mathematical Problems in Engineering , 2012, DOI: 10.1155/2012/194010
Numerical Modeling and Control of Rotating Plate with Coupled Self-Sensing and Frequency-Dependent Active Constrained Layer Damping
Zhengchao Xie,Pak Kin Wong,Long Zhang,Hang Cheong Wong
Mathematical Problems in Engineering , 2012, DOI: 10.1155/2012/194010
Abstract: This work proposes a coupled finite element model for actively controlled constrained layer damped (CLD) rotating plate with self-sensing technique and frequency-dependent material property in both the time and frequency domain analyses. Constrained layer damping with viscoelastic material can effectively reduce the vibration in rotating structures. However, most existing research models use complex modulus approach to model the viscoelastic material, but it limits to frequency domain analysis and the frequency dependency of the viscoelastic material is not well-included as well. It is meaningful use of the anelastic displacement fields (ADFs) that is done in order to include the frequency dependency of the material for both the time and frequency domains. Also, unlike previous ones, all types of damping are taken into account by this finite element model. Thus, in this work, a single layer finite element is adopted to model a three-layer active constrained layer damped rotating plate in which the constraining layer is made of piezoelectric material to work as both the self-sensing sensor and actuator. This newly proposed finite element model is validated, and then, as shown in numerical studies, this proposed approach can achieve effective vibration reduction in both the frequency and time domains. 1. Introduction Constrained layer damping (CLD) is an effective vibration reduction approach in which a damping layer made of viscoelastic material is sandwiched between the base structure and a constraining layer. In the deformation of this damping layer, a portion of the strain energy of the viscoelastic material is dissipated so that vibrational damping can be achieved. The damping ratio achieved by using this viscoelastic material is dependent on the frequency and environment temperature. At present, a wide variety of viscoelastic materials exists, so the study on the damping property of the viscoelastic material is an interesting topic. Recently, constrained layer damping is employed for the vibration suppressions of rotating structures, which has wide applications in industries such as wind turbines and helicopters. Rotating beams, as simplification of rotating plates, have been extensively investigated, including fundamental dynamics [1]. Yoo and Pierre [2] studied the dynamics of rotating bare plates using analytical approach. Based on the work in [2], Liu and Hong [3] developed a plate finite element model for a rotating bare plate. Xie and Xue [4] proposed a finite element model on passive constrained layer damped plate which can include more types
Complex band structure and plasmon lattice Green's function of a periodic metal-nanoparticle chain
Kin Hung Fung,Ross Chin Hang Tang,C. T. Chan
Physics , 2009, DOI: 10.1364/OL.36.002206
Abstract: When the surface plasmon resonance in a metal-nanoparticle chain is excited at one point, the response signal will generally decay down the chain due to absorption and radiation losses. The decay length is a key parameter in such plasmonic systems. By studying the plasmon lattice Green's function, we found that the decay length is generally governed by two exponential decay constants with phase factors corresponding to guided Bloch modes and one power-law decay with a phase factor corresponding to that of free space photons. The results show a high level of similarity between the absorptive and radiative decay channels. By analyzing the poles (and the corresponding residues) of the Green's function in a transformed complex reciprocal space, the dominant decay channel of the real-space Green's function is understood.
Portable Heart Rate Detector Based on Photoplethysmography with Android Programmable Devices for Ubiquitous Health Monitoring System
Chi Kin Lao,U Kin Che,Wei Chen,Sio Hang Pun
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems , 2013, DOI: 10.11601/ijates.v2i1.22
Abstract: In this paper, a miniature portable heart rate detector system is implemented by modern hardware ICs and simple sensor circuit with software executable on both PC and Android platform. The biosignal is first extracted via photoplethysmography (PPG) principle into electric signal. Then a microprocessor is used to covert biosignal from analog to digital format, suitably for feeding into an RF module (nRF24L01 for RF transmission). On the receiver end, the computer and/or smart phone can analyze the data using a robust algorithm that can detect peaks of the PPG waveform, hence to calculating the heart rate. Some application software running on Windows and Android phone have been developed to display heart rate information and time domain waveform to users for health care monitoring. In the future, pure Bluetooth technology will be used for wireless personal communications instead of RF modules. At the same time, the data can be sent to computer console using existing available networks (3G, 4G, WiFi, etc.) for health database logging purpose.
Factors of Acceptance for Mobile Learning in Corporate Settings: An Empirical Investigation in Banking Industry  [PDF]
Ayse Kok
Intelligent Information Management (IIM) , 2013, DOI: 10.4236/iim.2013.55015
Abstract: Due to the proliferation of mobile technology and devices like smartphones and tablet PCs into our daily lives, m-learning attracts also more attention in professional training in enterprises. Derived from these statements, this research paper is focused on the following question: what are acceptance factors for m-learning (mobile learning) in the organizational setting? The paper analyzes a real experience in m-learning for training the banking personnel in an international banking institution in Turkey. For this purpose, a mobile virtual learning environment called as mFOR@ was developed and implemented, which was designed to support the training and development process for employees using Pocket PCs. The participants of the training activity (13 professionals) evaluated the m-learning experience via a semi-structured interview; all the content and interactions within mFOR@ were analyzed via content analysis. As a basis for a successful implementation in professional training in enterprises, the acceptance by decision makers and the learners is critical. That is the reason why I present a qualitative analysis of acceptance and the perceived value of m-learning in a corporate setting.
Behind the Scenes with a Video Training Platform: The Challenges of Researching the Provision of Open Educational Resources  [PDF]
Ayse Kok
Advances in Internet of Things (AIT) , 2013, DOI: 10.4236/ait.2013.34009

Video training platforms are now being implemented on a large scale in organizations. In this paper, I look at a video training platform including open educational resources available for many employees with varying patterns and motivations for use. This has provided me with a research challenge to find methods that help other practitioners in the field understand and explain such initiatives. I describe ways to model the research and identify where pressures and contradictions can be found, drawing on a reflective view of my own practice in performing the research. Open educational resources are defined as technology-enabled educational resources that are openly available for consultation, use and adaptation by users for non-commercial purposes [1]. The bank subject to this case study has been the first organisation in Turkey that provided open educational resources for all its employees. The video platform (called “For @ Tube”) provides users with over 100 video lectures drawn from reputable universities around the world including Yale and Harvard. Other learning tools such as discussion forums, blogs and traditional e-learning courses have been made available to the users on the e-learning platform called “For @” since 2006. In this paper, I aim to introduce the new video training platform (“For @ Tube”) and outline some of the main research issues surrounding such an

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