33 results on '"Lim, Fabian"'
Search Results
2. Conserved enhancers control notochord expression of vertebrate Brachyury
- Author
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Kemmler, Cassie L., Smolikova, Jana, Moran, Hannah R., Mannion, Brandon J., Knapp, Dunja, Lim, Fabian, Czarkwiani, Anna, Hermosilla Aguayo, Viviana, Rapp, Vincent, Fitch, Olivia E., Bötschi, Seraina, Selleri, Licia, Farley, Emma, Braasch, Ingo, Yun, Maximina, Visel, Axel, Osterwalder, Marco, Mosimann, Christian, Kozmik, Zbynek, and Burger, Alexa
- Published
- 2023
- Full Text
- View/download PDF
3. Single-nucleotide variants within heart enhancers increase binding affinity and disrupt heart development
- Author
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Jindal, Granton A., Bantle, Alexis T., Solvason, Joe J., Grudzien, Jessica L., D’Antonio-Chronowska, Agnieszka, Lim, Fabian, Le, Sophia H., Song, Benjamin P., Ragsac, Michelle F., Klie, Adam, Larsen, Reid O., Frazer, Kelly A., and Farley, Emma K.
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- 2023
- Full Text
- View/download PDF
4. Protocol to electroporate DNA plasmids into Ciona robusta embryos at the 1-cell stage
- Author
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Jindal, Granton A., Lim, Fabian, Tellez, Krissie, Song, Benjamin P., Bantle, Alexis T., and Farley, Emma K.
- Published
- 2024
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- View/download PDF
5. Haptic Rendering for VR Laparoscopic Surgery Simulation
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McColl, Ryan, Brown, Ian, Seligman, Cory, Lim, Fabian, and Alsaraira, Amer
- Published
- 2006
6. A Visual Graphic / Haptic Rendering Model for Hysteroscopic Procedures
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Lim, Fabian, Brown, Ian, McColl, Ryan, Seligman, Cory, and Alsaraira, Amer
- Published
- 2006
7. Code automorphisims and permutation decoding of certain Reed-Solomon binary images
- Author
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Lim, Fabian, Fossorier, Marc, and Kavcic, Aleksandar
- Subjects
Company business management ,Reed-Solomon codes -- Management ,Decoders -- Research ,Permutations -- Analysis ,Binary-coded notation -- Research - Published
- 2010
8. Ordered statistics decoding of linear block codes over intersymbol interference channels
- Author
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Lim, Fabian, Kavcic, Aleksandar, and Fossorier, Marc
- Subjects
Algorithms -- Analysis ,Decoders -- Analysis ,Algorithm ,Business ,Electronics ,Electronics and electrical industries - Abstract
In this paper, we utilize ordered statistics decoding (OSD) techniques for intersymbol interference (ISI) channels. To achieve good efficiency and storage complexity, a combination of a modified generalized Viterbi algorithm (GVA) and Battairs algorithm is proposed to implement OSD for ISI channels. Simulation results showed significant performance improvement for the [128,64,22] eBCH code, and the [255,239,17] Reed-Solomon (RS) binary image, on the [(1 + D).sup.2] perpendicular recording channel. Index Terms--Decoding, intersymbol interference, linear block codes, Reed-Solomon codes.
- Published
- 2008
9. Reliability Distributions of Truncated Max-log-map (MLM) Detectors Applied to ISI Channels
- Author
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Lim, Fabian and Kavcic, Aleksandar
- Subjects
FOS: Computer and information sciences ,Information Theory (cs.IT) ,Computer Science - Information Theory - Abstract
The max-log-map (MLM) receiver is an approximated version of the well-known, Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm. The MLM algorithm is attractive due to its implementation simplicity. In practice, sliding-window implementations are preferred; these practical implementations consider truncated signaling neighborhoods around each transmission time instant. In this paper, we consider sliding-window MLM receivers, where for any integer m, the MLM detector is truncated to a length- m signaling neighborhood. For any number n of chosen times instants, we derive exact expressions for both i) the joint distribution of the MLM symbol reliabilities, and ii) the joint probability of the erroneous MLM symbol detections. We show that the obtained expressions can be efficiently evaluated using Monte-Carlo techniques. Our proposed method is efficient; the most computationally expensive operation (in each Monte-Carlo trial) is an eigenvalue decomposition of a size 2mn by 2mn matrix. Practical truncation lengths can be easily handled. Finally, our proposed method is extremely general, and various scenarios such as correlated noise distributions, modulation coding, etc. may be easily accommodated., 17 pages, 11 figures
- Published
- 2010
10. The Single-Uniprior Index-Coding Problem: The Single-Sender Case and the Multi-Sender Extension.
- Author
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Ong, Lawrence, Ho, Chin Keong, and Lim, Fabian
- Subjects
CODING theory ,PROBLEM solving ,BROADCASTING industry ,COMPUTER algorithms ,DIRECTED graphs - Abstract
Index coding studies multiterminal source-coding problems where a set of receivers are required to decode multiple (possibly different) messages from a common broadcast, and they each know some messages a priori. In this paper, at the receiver end, we consider a special setting where each receiver knows only one message a priori, and each message is known to only one receiver. At the broadcasting end, we consider a generalized setting where there could be multiple senders, and each sender knows a subset of the messages. The senders collaborate to transmit an index code. This paper looks at minimizing the number of total coded bits the senders are required to transmit. When there is only one sender, we propose a pruning algorithm to find a lower bound on the optimal (i.e., the shortest) index codelength, and show that it is achievable by linear index codes. When there are two or more senders, we propose an appending technique to be used in conjunction with the pruning technique to give a lower bound on the optimal index codelength; we also derive an upper bound based on cyclic codes. While the two bounds do not match in general, for the special case where no two distinct senders know any message in common, the bounds match, giving the optimal index codelength. The results are expressed in terms of strongly connected components in directed graphs that represent the index-coding problems. [ABSTRACT FROM AUTHOR]
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- 2016
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11. Real-time interactive isosurfacing: a new method for improving marching isosurfacing algorithm output and efficiency.
- Author
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Ruthenbeck, Greg S., Lim, Fabian S., and Reynolds, Karen J.
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ALGORITHMS , *INDUSTRIAL efficiency , *SIMULATION methods & models , *TETRAHEDRA , *MESH analysis (Electric circuits) - Abstract
Efficient rendering of a changing volumetric data-set is central to the development of effective medical simulations that incorporate haptic feedback. A new method referred to as real-time interactive isosurfacing (RTII) is described in this paper. RTII is an algorithm that can be applied to output from Marching Cubes-like algorithms to improve performance for real-time applications. The approach minimises processing by re-evaluating the isosurface around changing sub-volumes resulting from user interactions. It includes innovations that significantly reduce mesh complexity and improve mesh quality as triangles are created from the Marching Tetrahedra isosurfacing algorithm. Rendering efficiency is further improved over other marching isosurfacing algorithm outputs by maintaining an indexed triangle representation of the mesh. The effectiveness of RTII is discussed within the context of an endoscopic sinus surgery simulation currently being developed by the authors. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
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12. The multi-sender multicast index coding.
- Author
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Ong, Lawrence, Lim, Fabian, and Ho, Chin Keong
- Published
- 2013
- Full Text
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13. On Directional-Search Procedures for Orbifolds: Connections with the Manifold Framework.
- Author
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Lim, Fabian
- Published
- 2013
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14. Linear programming upper bounds on permutation code sizes from coherent configurations related to the Kendall-tau distance metric.
- Author
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Lim, Fabian and Hagiwara, Manabu
- Abstract
Recent interest on permutation rank modulation shows the Kendall-tau metric as an important distance metric. This note documents our first efforts to obtain upper bounds on optimal code sizes (for said metric) ala Delsarte's approach. For the Hamming metric, Delsarte's seminal work on powerful linear programming (LP) bounds have been extended to permutation codes, via association scheme theory. For the Kendall-tau metric, the same extension needs the more general theory of coherent configurations, whereby the optimal code size problem can be formulated as an extremely huge semidefinite programming (SDP) problem. Inspired by recent algebraic techniques for solving SDP's, we consider the dual problem, and propose an LP to search over a subset of dual feasible solutions. We obtain modest improvement over a recent Singleton bound due to Barg and Mazumdar. We regard this work as a starting point, towards fully exploiting the power of Delsarte's method, which are known to give some of the best bounds in the context of binary codes. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
15. Non-asymptotic analysis of compressed sensing random matrices: An U-statistics approach.
- Author
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Lim, Fabian and Stojanovic, Vladimir Marko
- Abstract
We apply Heoffding's U-statistics to obtain non-asymptotic analysis for compressed sensing (CS) random matrices. These powerful (U-statistics) tools appear to apply naturally to CS theory, in particular here we focus on one particular large deviation result. We chose two applications to outline how U-statistics may apply to various CS recovery guarantees. Pros, cons, and further directions of the approach, are discussed. Restricted isometries of random matricies have well-regarded importance in CS. They guarantee i) uniqueness of sparse solutions, and ii) robust recovery. The fraction of size-k submatrices (out of all (n/k) of them), that satisfy CS-type restricted isometeries, is an U-statistic. Concentration of U-statistics predict the “average-case” behavior of such isometries. U-statistics related to Fuchs' conditions for ℓ1-minimization support recovery, are derived. This leads to bounds on the fraction of recoverable k-supports. Empirically, we observe significant improvement over a recent large deviation (non-asymptotic) bound by Donoho & Tanner, for some practical system sizes with large undersampling. The results apply regardless of column distribution, e.g. Gaussian, Bernoulli, etc. Similar concentration behavior has been empirically observed, when the sampling matrix is constructed using pseudorandom sequences (important in practice). [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
16. Performance trade-offs and design limitations of analog-to-information converter front-ends.
- Author
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Abari, Omid, Chen, Fred, Lim, Fabian, and Stojanovic, Vladimir
- Abstract
This paper evaluates the impact of circuit impairments on the energy cost and performance limitations of analog-to-information converters (AIC). In applications where signal frequencies are high, but information bandwidths are low, AICs have been proposed as a potential solution to overcome the resolution and performance limitations of sampling jitter in high-speed analog-to-digital converters (ADC). Although the AIC architecture facilitates slower ADCs, the signal encoding, typically realized with a mixer-like circuit, still occurs at the Nyquist frequency of the input to avoid aliasing. We show that the jitter of this mixing stage limits the achievable AIC resolution. In this work, the end-to-end system evaluation framework is designed to analyze these limitations as well as the relative energy-efficiency of AICs versus ADCs across the resolution, receiver gain and signal sparsity. The evaluation shows that AICs improve the resolution by 1 bit when the signal of interest is very sparse, and enable 2× in energy savings when no pre-amplification is required. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
17. Analysis and optimized equalizer design for threshold-like detectors for d=1 optical recording channels.
- Author
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Chan, Kheong Sann and Lim, Fabian
- Published
- 2004
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18. Reliability Distributions of Truncated Max-Log-MAP (MLM) Detectors Applied to Binary ISI Channels.
- Author
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Lim, Fabian and Kavcic, Aleksandar
- Subjects
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RADIO detectors , *DISTRIBUTION (Probability theory) , *CHANNEL capacity (Telecommunications) , *BINARY control systems , *COMPUTER algorithms - Abstract
The max-log-MAP (MLM) receiver is an approximated version of the well-known Bahl–Cocke–Jelinek-Raviv algorithm. The MLM algorithm is attractive due to its implementation simplicity. In practice, sliding-window implementations are preferred, whereby truncated signaling neighborhoods (around each transmission time instant) are considered. In this paper, we consider binary signaling sliding-window MLM receivers, where the MLM detector is truncated to a length-m signaling neighborhood. Here, truncation is used to ease the burden of analysis. For any number n of chosen times instants, we derive exact expressions for both 1) the joint distribution of the MLM symbol reliabilities, and 2) the joint probability of the erroneous MLM symbol detections. We show that the obtained expressions can be efficiently evaluated using Monte–Carlo techniques. The most computationally expensive operation (in each Monte–Carlo trial) is an eigenvalue decomposition of a size 2mn \times 2mn matrix. The proposed method handles various scenarios such as correlated noise distributions, modulation coding, etc. [ABSTRACT FROM PUBLISHER]
- Published
- 2013
- Full Text
- View/download PDF
19. Usability of Tablet Computers by People with Early-Stage Dementia.
- Author
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S. Lim, Fabian, Wallace, Tim, Luszcz, Mary A., and Reynolds, Karen J.
- Subjects
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DEMENTIA patients , *TABLET computers , *ONLINE social networks , *EVERYDAY life , *LEISURE , *SOCIAL networks , *DYADS - Abstract
Background: Tablet computers are generally associated with an intuitive interface. The adoption and use of tablet computers within the early-stage dementia context could potentially assist in daily living and provide users with a source for leisure activities and social networking. As dementia mainly affects the older adult population, it is expected that many people with dementia and even their carers do not use tablet computers as part of their everyday living. Objective: This paper explores the usability of tablet computers within the early-stage dementia context as a source of leisure for people with dementia. The main advantage of the use of tablet computers in this manner is to provide carers some reprieve from the constant care and attention often required in caring for people with dementia. Methods: Seven-day in-home trials were conducted to determine whether people with early-stage dementia were capable of using a tablet computer independently. Twenty-one people with early-stage dementia and carer dyads participated in the trial. Feedback was gathered through questionnaires from both the person with dementia and their carer regarding the use of a tablet computer as part of their everyday living. Results; Approximately half the participants with dementia were able to engage with and use the tablet computer independently, which proved to be helpful to their carers. No significant traits were observed to help identify those who were less likely to use a tablet computer. Carer relief was quantified by the amount of time participants with dementia spent using the device without supervision. Conclusions: The results and feedback from the trial provide significant insights to introducing new technology within the early-stage dementia context. Users' needs must be considered on a case-by-case basis to successfully facilitate the uptake of tablet computers in the dementia context. The trial has provided sufficient justification to further explore more uses of tablet computers in the dementia context, and not just for early-stage dementia. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
20. Virtual Reality Grocery Shopping Simulator: Development and Usability in Neurological Rehabilitation.
- Author
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Laver, Kate, Lim, Fabian, Reynolds, Karen, George, Stacey, Ratcliffe, Julie, Sim, Sharon, and Crotty, Maria
- Subjects
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VIRTUAL reality , *GROCERY shopping , *PERFORMANCE , *LIFE skills , *TREATMENT programs , *SIMULATION software , *REHABILITATION - Abstract
Few virtual reality programs have been designed to retrain performance of activities of daily living for people undergoing neurological rehabilitation. This is despite the advantages of using this type of approach, including task-specifc practice of meaningful and relevant activities. This paper summarizes the development of a grocery shopping simulator which uses a novel approach to interaction between the user and the program. The shopping simulation program underwent usability testing with patients participating in neurological rehabilitation. The results indicated that patients found the program easy and enjoyable to use and felt it would be a useful part of a rehabilitation program. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
21. Analysis of Shingle-Write Readback Using Magnetic-Force Microscopy.
- Author
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Lim, Fabian, Wilson, Bruce, and Wood, Roger
- Subjects
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MAGNETIC force microscopy , *SCANNING force microscopy , *MAGNETIC resonance force microscopy , *DATA tapes , *MAGNETIC tapes - Abstract
The article reports on shingle recording experiments which were conducted on a precision spin-stand using conventional recording components. During the experiments, although both head and medium correspond to a 250 Gb/in² Gigabits/sq. inch) product, the raw written densities were pushed beyond 1 Tb/in² (Terabits/sq. inch). Researchers used high-resolution magnetic-force microscopy to examine the resulting written patterns. They found that the microscopy images have an apparent resolution down to 16 nm. As a result of the images researchers were able to characterize the signal and noise in two dimensions up to the highest densities. They applied two-dimensional signal-processing to the "waveforms" recovered from the microscopy images. They found that at the highest written densities, very poor raw error-rates were encountered and customer data could only be recovered successfully by employing relatively low rate codes. They concluded that although the experiments pushed the raw recording density to 1039 Gb/in², the highest customer information density at which data was successfully recovered was 623 Gb/in²
- Published
- 2010
- Full Text
- View/download PDF
22. List Decoding Techniques for Intersymbol Interference Channels Using Ordered Statistics.
- Author
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Lim, Fabian, Kavčić, Aleksandar, and Fossorier, Marc
- Subjects
REED-Solomon codes ,STATISTICS ,ECONOMETRICS ,ALGORITHMS ,ERROR analysis in mathematics - Abstract
In this paper, we present a generalization of the ordered statistics decoding (OSD) techniques for the class of intersymbol interference (ISI) channels, and show decoding results for the extended Bose-Chaudhuri-Hocquenghem (eBCH) [128,64,22] code and the [255,239, 17] Reed-Solomon (RS) binary image, over the PR2 partial response channel. Using the generalized OSD technique, we go on to generalize the Box-and- Match Algorithm (BMA) to the class of ISI channels. The BMA is an enhancement of OSD, and prior work has shown it to provide significant performance gain over OSD for memoryless additive white Gaussian noise (AWGN) channels. We present decoding results of the BMA for ISI channels, for the same eBCH and RS (binary image) codes, and PR2 channel. Our results show that the BMA (generalized for ISI channels) is superior to the OSD in terms of its performance/complexity trade-off. More specifically, the BMA may be tuned such that both algorithms have similar complexity, whereby the BMA still outperforms the OSD by a significant margin. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
23. Why Analog-to-Information Converters Suffer in High-Bandwidth Sparse Signal Applications.
- Author
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Abari, Omid, Lim, Fabian, Chen, Fred, and Stojanovic, Vladimir
- Subjects
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INFORMATION theory , *CONVERTERS (Electronics) , *BANDWIDTHS , *SIGNALS & signaling , *ANALOG-to-digital converters , *INTEGRATED circuits , *MATHEMATICAL models - Abstract
In applications where signal frequencies are high, but information bandwidths are low, analog-to-information converters (AICs) have been proposed as a potential solution to overcome the resolution and performance limitations of high-speed analog-to-digital converters (ADCs). However, the hardware implementation of such systems has yet to be evaluated. This paper aims to fill this gap, by evaluating the impact of circuit impairments on performance limitations and energy cost of AICs. We point out that although the AIC architecture facilitates slower ADCs, the signal encoding, typically realized with a mixer-like circuit, still occurs at the Nyquist frequency of the input to avoid aliasing. We illustrate that the jitter and aperture of this mixing stage limit the achievable AIC resolution. In order to do so, we designed an end-to-end system evaluation framework for examining these limitations, as well as the relative energy-efficiency of AICs versus high-speed ADCs across the resolution, receiver gain and signal sparsity. The evaluation shows that the currently proposed AICs have no performance benefits over high-speed ADCs. However, AICs enable 2–10X in energy savings in low to moderate resolution (ENOB), low gain applications. [ABSTRACT FROM PUBLISHER]
- Published
- 2013
- Full Text
- View/download PDF
24. Energy-Aware Design of Compressed Sensing Systems for Wireless Sensors Under Performance and Reliability Constraints.
- Author
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Chen, Fred, Lim, Fabian, Abari, Omid, Chandrakasan, Anantha, and Stojanovic, Vladimir
- Subjects
- *
COMPRESSED sensing , *WIRELESS sensor networks , *QUANTIZATION (Physics) , *ELECTROCARDIOGRAPHY , *SYSTEM analysis - Abstract
This paper describes the system design of a compressed sensing (CS) based source encoding system for data compression in wireless sensor applications. We examine the trade-off between the required transmission energy (compression performance) and desired recovered signal quality in the presence of practical non-idealities such as quantization noise, input signal noise and channel errors. The end-to-end system evaluation framework was designed to analyze CS performance under practical sensor settings. The evaluation shows that CS compression can enable over 10X in transmission energy savings while preserving the recovered signal quality to roughly 8 bits of precision. We further present low complexity error control schemes tailored to CS that further reduce the energy costs by 4X as well as diversity scheme to protect against burst errors. Results on a real electrocardiography (EKG) signal demonstrate 10X in energy reduction and corroborate the system analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
25. Virtual reality grocery shopping simulator: development and usability in neurological rehabilitation
- Author
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Kate Laver, Maria Crotty, Julie Ratcliffe, Karen J. Reynolds, Sharon Sim, Stacey George, Fabian Lim, Laver, Kate, Lim, Fabian, Reynolds, Karen, George, Stacey, Ratcliffe, Julie, Sim, Sharon, and Crotty, Maria
- Subjects
Activities of daily living ,Rehabilitation ,business.industry ,Computer science ,medicine.medical_treatment ,Usability ,Virtual reality ,simulation software ,Human-Computer Interaction ,Control and Systems Engineering ,randomized controlled-trial ,Neurological rehabilitation ,medicine ,virtual reality ,life skills ,Computer Vision and Pattern Recognition ,business ,Software ,Simulation ,Grocery shopping ,stroke rehabilitation ,grocery shopping - Abstract
Few virtual reality programs have been designed to retrain performance of activities of daily living for people undergoing neurological rehabilitation. This is despite the advantages of using this type of approach, including task-specific practice of meaningful and relevant activities. This paper summarizes the development of a grocery shopping simulator which uses a novel approach to interaction between the user and the program. The shopping simulation program underwent usability testing with patients participating in neurological rehabilitation. The results indicated that patients found the program easy and enjoyable to use and felt it would be a useful part of a rehabilitation program. Refereed/Peer-reviewed
- Published
- 2012
26. Conserved enhancer logic controls the notochord expression of vertebrate Brachyury .
- Author
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Kemmler CL, Smolikova J, Moran HR, Mannion BJ, Knapp D, Lim F, Czarkwiani A, Hermosilla Aguayo V, Rapp V, Fitch OE, Bötschi S, Selleri L, Farley E, Braasch I, Yun M, Visel A, Osterwalder M, Mosimann C, Kozmik Z, and Burger A
- Abstract
The cell type-specific expression of key transcription factors is central to development. Brachyury/T/TBXT is a major transcription factor for gastrulation, tailbud patterning, and notochord formation; however, how its expression is controlled in the mammalian notochord has remained elusive. Here, we identify the complement of notochord-specific enhancers in the mammalian Brachyury/T/TBXT gene. Using transgenic assays in zebrafish, axolotl, and mouse, we discover three Brachyury -controlling notochord enhancers T3 , C , and I in human, mouse, and marsupial genomes. Acting as Brachyury-responsive, auto-regulatory shadow enhancers, deletion of all three enhancers in mouse abolishes Brachyury/T expression selectively in the notochord, causing specific trunk and neural tube defects without gastrulation or tailbud defects. Sequence and functional conservation of Brachyury -driving notochord enhancers with the brachyury/tbxtb loci from diverse lineages of fishes dates their origin to the last common ancestor of jawed vertebrates. Our data define the enhancers for Brachyury/T/TBXTB notochord expression as ancient mechanism in axis development., Competing Interests: Competing financial interests The authors declare no competing financial interests.
- Published
- 2023
- Full Text
- View/download PDF
27. 3D genomics across the tree of life reveals condensin II as a determinant of architecture type.
- Author
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Hoencamp C, Dudchenko O, Elbatsh AMO, Brahmachari S, Raaijmakers JA, van Schaik T, Sedeño Cacciatore Á, Contessoto VG, van Heesbeen RGHP, van den Broek B, Mhaskar AN, Teunissen H, St Hilaire BG, Weisz D, Omer AD, Pham M, Colaric Z, Yang Z, Rao SSP, Mitra N, Lui C, Yao W, Khan R, Moroz LL, Kohn A, St Leger J, Mena A, Holcroft K, Gambetta MC, Lim F, Farley E, Stein N, Haddad A, Chauss D, Mutlu AS, Wang MC, Young ND, Hildebrandt E, Cheng HH, Knight CJ, Burnham TLU, Hovel KA, Beel AJ, Mattei PJ, Kornberg RD, Warren WC, Cary G, Gómez-Skarmeta JL, Hinman V, Lindblad-Toh K, Di Palma F, Maeshima K, Multani AS, Pathak S, Nel-Themaat L, Behringer RR, Kaur P, Medema RH, van Steensel B, de Wit E, Onuchic JN, Di Pierro M, Lieberman Aiden E, and Rowland BD
- Subjects
- Adenosine Triphosphatases chemistry, Algorithms, Animals, Cell Nucleolus ultrastructure, Cell Nucleus ultrastructure, Centromere ultrastructure, Chromosomes chemistry, Chromosomes, Human chemistry, Chromosomes, Human ultrastructure, DNA-Binding Proteins chemistry, Genome, Human, Genomics, Heterochromatin ultrastructure, Humans, Interphase, Mitosis, Models, Biological, Multiprotein Complexes chemistry, Telomere ultrastructure, Adenosine Triphosphatases genetics, Adenosine Triphosphatases physiology, Biological Evolution, Chromosomes ultrastructure, DNA-Binding Proteins genetics, DNA-Binding Proteins physiology, Eukaryota genetics, Genome, Multiprotein Complexes genetics, Multiprotein Complexes physiology
- Abstract
We investigated genome folding across the eukaryotic tree of life. We find two types of three-dimensional (3D) genome architectures at the chromosome scale. Each type appears and disappears repeatedly during eukaryotic evolution. The type of genome architecture that an organism exhibits correlates with the absence of condensin II subunits. Moreover, condensin II depletion converts the architecture of the human genome to a state resembling that seen in organisms such as fungi or mosquitoes. In this state, centromeres cluster together at nucleoli, and heterochromatin domains merge. We propose a physical model in which lengthwise compaction of chromosomes by condensin II during mitosis determines chromosome-scale genome architecture, with effects that are retained during the subsequent interphase. This mechanism likely has been conserved since the last common ancestor of all eukaryotes., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
- Published
- 2021
- Full Text
- View/download PDF
28. Usability of tablet computers by people with early-stage dementia.
- Author
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Lim FS, Wallace T, Luszcz MA, and Reynolds KJ
- Subjects
- Adult, Aged, Aged, 80 and over, Alzheimer Disease nursing, Caregivers, Dementia nursing, Dementia psychology, Female, Humans, Male, Middle Aged, Patient Satisfaction, Surveys and Questionnaires, User-Computer Interface, Alzheimer Disease psychology, Attitude to Computers, Computers, Handheld, Leisure Activities
- Abstract
Background: Tablet computers are generally associated with an intuitive interface. The adoption and use of tablet computers within the early-stage dementia context could potentially assist in daily living and provide users with a source for leisure activities and social networking. As dementia mainly affects the older adult population, it is expected that many people with dementia and even their carers do not use tablet computers as part of their everyday living., Objective: This paper explores the usability of tablet computers within the early-stage dementia context as a source of leisure for people with dementia. The main advantage of the use of tablet computers in this manner is to provide carers some reprieve from the constant care and attention often required in caring for people with dementia., Methods: Seven-day in-home trials were conducted to determine whether people with early-stage dementia were -capable of using a tablet computer independently. Twenty-one people with early-stage dementia and carer dyads participated in the trial. Feedback was gathered through questionnaires from both the person with dementia and their carer regarding the use of a tablet computer as part of their everyday living., Results: Approximately half the participants with dementia were able to engage with and use the tablet computer independently, which proved to be helpful to their carers. No significant traits were observed to help identify those who were less likely to use a tablet computer. Carer relief was quantified by the amount of time participants with dementia spent using the device without supervision., Conclusions: The results and feedback from the trial provide significant insights to introducing new technology within the early-stage dementia context. Users' needs must be considered on a case-by-case basis to successfully facilitate the uptake of tablet computers in the dementia context. The trial has provided sufficient justification to further explore more uses of tablet computers in the dementia context, and not just for early-stage dementia., (Copyright © 2012 S. Karger AG, Basel.)
- Published
- 2013
- Full Text
- View/download PDF
29. A prospective cohort study on the impact of a modified Basic Military Training (mBMT) programme based on pre-enlistment fitness stratification amongst Asian military enlistees.
- Author
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Chai LY, Ong KC, Kee A, Earnest A, Lim FC, and Wong JC
- Subjects
- Adolescent, Asian People, Body Mass Index, Cohort Studies, Exercise Test statistics & numerical data, Humans, Male, Oxygen Consumption, Physical Education and Training standards, Program Evaluation, Prospective Studies, Risk Assessment, Singapore, Time Factors, Young Adult, Military Personnel statistics & numerical data, Physical Education and Training methods, Physical Fitness, Running physiology
- Abstract
Introduction: This study objectively evaluates the effectiveness of a 6-week Preparatory Training Phase (PTP) programme prior to Basic Military Training (BMT) for less physically conditioned conscripts in the Singapore Armed Forces., Materials and Methods: We compared exercise test results of a group of less fi t recruits who underwent a 16-week modified-BMT (mBMT) programme (consisting of a 6-week PTP and 10-week BMT phase) with their 'fitter' counterparts enlisted in the traditional 10-week direct-intake BMT (dBMT) programme in this prospective cohort study consisting of 36 subjects. The main outcome measures included cardiopulmonary responses parameters (VO(2)max and V(O2AT)) with clinical exercise testing and distance run timings., Results: Although starting off at a lower baseline in terms of physical fitness [VO(2)max 1.73 +/- 0.27 L/min (mBMT group) vs 1.97 +/- 0.43 L/min (dBMT), P = 0.032; V(O2AT) 1.02 +/- 0.19 vs 1.14 +/- 0.32 L/min respectively, P = 0.147], the mBMT group had greater improvement in cardiopulmonary indices and physical performance profiles than the dBMT cohort as determined by cardiopulmonary exercise testing [VO(2)max 2.34 +/- 0.24 (mBMT) vs 2.36 +/- 0.36 L/min (dBMT), P = 0.085; V(O2AT) 1.22 +/- 0.17 vs 1.21 +/- 0.24 L/min respectively, P = 0.303] and 2.4 kilometres timed-run [mBMT group 816.1 sec (pre-BMT) vs 611.1 sec (post-BMT), dBMT group 703.8 sec vs 577.7 sec, respectively; overall P value 0.613] at the end of the training period. Initial mean difference in fitness between mBMT and dBMT groups on enlistment was negated upon graduation from BMT., Conclusion: Pre-enlistment fitness stratification with training modification in a progressive albeit longer BMT programme for less-conditioned conscripts appears efficacious when measured by resultant physical fitness.
- Published
- 2009
30. Instrument-tissue segment interaction using finite element modeling.
- Author
-
Alsaraira A, Brown I, McColl R, and Lim F
- Subjects
- Elasticity, General Surgery education, Robotics, Software, Computer-Assisted Instruction, Finite Element Analysis, Laparoscopy, Models, Anatomic
- Abstract
A virtual reality based laparoscopic surgery simulator is an important training option for laparoscopic surgeons. It has significant advantages over other training methods. Instruments-anatomy interactions are one of the main features of these simulators. In this paper we present the deformation of the uterine tube using three dimensional finite element methods with finite element software. The work examines the feasibility of incorporating the finite element (FE) model within the visual graphic model to achieve high degree of realism of instrument-tissue interactions.
- Published
- 2007
- Full Text
- View/download PDF
31. A visual graphic/haptic rendering model for hysteroscopic procedures.
- Author
-
Lim F, Brown I, McColl R, Seligman C, and Alsaraira A
- Subjects
- Feedback, Female, Humans, Imaging, Three-Dimensional methods, Software, Software Design, Uterus anatomy & histology, Uterus surgery, Computer Graphics, Computer-Assisted Instruction methods, Gynecologic Surgical Procedures education, Gynecologic Surgical Procedures methods, Hysteroscopy methods, Models, Anatomic, User-Computer Interface
- Abstract
Hysteroscopy is an extensively popular option in evaluating and treating women with infertility. The procedure utilises an endoscope, inserted through the vagina and cervix to examine the intra-uterine cavity via a monitor. The difficulty of hysteroscopy from the surgeon's perspective is the visual spatial perception of interpreting 3D images on a 2D monitor, and the associated psychomotor skills in overcoming the fulcrum-effect. Despite the widespread use of this procedure, current qualified hysteroscopy surgeons have not been trained the fundamentals through an organised curriculum. The emergence of virtual reality as an educational tool for this procedure, and for other endoscopic procedures, has undoubtedly raised interests. The ultimate objective is for the inclusion of virtual reality training as a mandatory component for gynaecologic endoscopy training. Part of this process involves the design of a simulator, encompassing the technical difficulties and complications associated with the procedure. The proposed research examines fundamental hysteroscopy factors, current training and accreditation, and proposes a hysteroscopic simulator design that is suitable for educating and training.
- Published
- 2006
32. Hysteroscopic simulator for training and educational purposes.
- Author
-
Lim F, Brown I, McColl R, Seligman C, and Alsaraira A
- Subjects
- Computer Simulation, Computer-Assisted Instruction instrumentation, Equipment Design, Equipment Failure Analysis, Female, Gynecologic Surgical Procedures education, Gynecologic Surgical Procedures instrumentation, Humans, Models, Anatomic, Reproducibility of Results, Sensitivity and Specificity, Computer-Assisted Instruction methods, Hysteroscopes, Hysteroscopy methods, Models, Biological, Surgery, Computer-Assisted instrumentation, Surgery, Computer-Assisted methods, User-Computer Interface
- Abstract
Hysteroscopy is an extensively popular option in evaluating and treating women with infertility. The procedure utilizes an endoscope, inserted through the vagina and cervix to examine the intra-uterine cavity via a monitor. The difficulty of hysteroscopy from the surgeon's perspective is the visual spatial perception of interpreting 3D images on a 2D monitor, and the associated psychomotor skills in overcoming the fulcrum-effect. Despite the widespread use of this procedure, current qualified hysteroscopy surgeons have not been trained the fundamentals through an organized curriculum. The emergence of virtual reality as an educational tool for this procedure, and for other endoscopic procedures, has undoubtedly raised interests. The ultimate objective is for the inclusion of virtual reality training as a mandatory component for gynecological endoscopic training. Part of this process involves the design of a simulator, encompassing the technical difficulties and complications associated with the procedure. The proposed research examines fundamental hysteroscopic factors as well as current training and accreditation norms, and proposes a hysteroscopic simulator design that is suitable for educating and training.
- Published
- 2006
- Full Text
- View/download PDF
33. Haptic rendering & perception studies for laparoscopic surgery simulation.
- Author
-
McColl R, Brown AP, Seligman C, Lim F, and Alsaraira A
- Subjects
- Adult, Computer Simulation, Humans, Male, Stress, Mechanical, Laparoscopy methods, Models, Biological, Physical Stimulation methods, Surgery, Computer-Assisted methods, Touch physiology, User-Computer Interface
- Abstract
This project concerns the application of haptic feedback to a virtual reality laparoscopic surgery simulator. Haptic attributes such as mass, friction, stiction, elasticity, roughness and viscosity are individually modeled, validated and applied to the existing visual simulation created by researchers at Monash University. Validation studies has shown that refinements to our mechanical interface improves the accuracy of localisation by 25%. Using our mechanical interface, the JND (Just Noticeable Difference) for instantaneous change of magnitude of haptic attributes is approximately 12%. This suggests the mechanical interface is suitable to use for surgery based studies. There are times in surgery when the view from the camera cannot be depended upon. When visual feedback is impeded, haptic feedback must be relied upon more by the surgeon. A realistic simulator should include some sort of visual impedance. Results from a simple tissue holding task suggested the inclusion of haptic feedback in a simulator aids the user when visual feedback is impeded. Haptic force feedback modeling, systems implementation, threshold and level perception, and validation studies form the principal areas of new work associated with this project.
- Published
- 2006
- Full Text
- View/download PDF
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