Antipersistant Effects in the Dynamics of a Competing Population

K. H. Lee,K. Y. Michael Wong 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.1I

We consider a population of agents competing for finite resources by using strategies based on two channels of signals. The model is applicable to financial markets, ecosystems and computer networks. We find that the dynamics of the system is determined by the correlation between the two channels. In particular, occasional mismatches of the signals induce a series of transitions among numerous attractors. Surprisingly, in contrast to the effects of noises on dynamical systems normally resulting in a large number of attractors, the number of attractors due to the mismatched signals remains finite. Both simulations and analyses show that this can be explained by the antipersistent nature of the dynamics. Antipersistence refers to the response of the system to a given signal being opposite to that of the signal’s previous occurrence and is a consequence of the competition of agents to make minority decisions. Thus, it is essential for stabilizing the dynamical systems.

Use of glecaprevir/pibrentasvir in patients with chronic hepatitis C virus infection and severe renal impairment

Desmond Y. H. Yap,Kevin S. H. Liu,Yu-Chun Hsu,Grace L. H. Wong,Ming-Chang Tsai,Chien-Hung Chen,Ching-Sheng Hsu,Yee Tak Hui,Michael K. K. Li,Chen-Hua Liu,Yee-Man Kan,Ming-Lung Yu,Man-Fung Yuen 대한간학회 2020 Clinical and Molecular Hepatology(대한간학회지) Vol.26 No.4

Background/Aims: Data on treatment efficacy and safety of glecaprevir/pibrentasvir (GLE/PIB) for chronic hepatitis C virus (HCV) infection in Asian patients with severe renal impairment are limited. This study aimed to study the treatment and side effects of GLE/PIB in these patients infected with non-1 genotype (GT) HCV. Methods: We prospectively recruited patients with Child’s A cirrhosis and eGFR <30 mL/min/1.73 m2 in Hong Kong and Taiwan during 2017–2018 to receive GLE/PIB treatment. Results: Twenty-one patients (GT2, n=7; GT3, n=6; and GT6, n=8) received GLE/PIB for 11.2±1.8 weeks. All except one were treatment-naïve. GLE/PIB was initiated in 16 patients while on dialysis (seven on peritoneal dialysis [PD] and nine on hemodialysis) and in five patients before dialysis. One patient died of PD-related peritonitis during treatment and two were lost to follow up. The SVR12 rate in the remaining 18 patients was 100%. All patients achieved undetectable levels at 4-, 12-, 24- and 48-week after treatment. Patients with deranged alanine aminotransferase showed normalization after 4 weeks and the response was sustained for 48 weeks. No significant adverse event was observed. Conclusions: GLE/PIB treatment was associated with high efficacy and tolerability in HCV-infected patients with severe renal impairment.

Tissue Expanders in Staged Calvarial Reconstruction: A Systematic Review

Andrea Y. Lo,Roy P. Yu,Anjali C. Raghuram,Michael N. Cooper,Holly J. Thompson,Charles Y. Liu,Alex K. Wong 대한성형외과학회 2022 Archives of Plastic Surgery Vol.49 No.6

Cranioplasties are common procedures in plastic surgery. The use of tissue expansion (TE) in staged cranioplasties is less common. We present two cases of cranioplasties with TE and systematically review literature describing the use of TE in staged cranioplasties and postoperative outcomes. A systematic review was performed by querying multiple databases. Eligible articles include published case series, retrospective reviews, and systematic reviews that described use of TE for staged bony cranioplasty. Data regarding study size, patient demographics, preoperative characteristics, staged procedure characteristics, and postoperative outcomes were collected. Of 755 identified publications, 26 met inclusion criteria. 85 patients underwent a staged cranioplasty with TE. Average defect size was 122 cm2, and 30.9% of patients received a previous reconstruction. Average expansion period was 14.2 weeks. The most common soft tissue closures were performed with skin expansion only (75.3%), free/pedicled flap (20.1%), and skin graft (4.7%). The mean postoperative follow-up time was 23.9 months. Overall infection and local complication rates were 3.53 and 9.41%, respectively. The most common complications were cerebrospinal fluid leak (7.1%), hematoma (7.1%), implant exposure (3.5%), and infection (3.5%). Factors associated with higher complication rates include the following: use of alloplastic calvarial implants and defects of congenital etiology (p¼0.023 and 0.035, respectively). This is the first comprehensive review to describe current practices and outcomes in staged cranioplasty with TE. Adequate soft tissue coverage contributes to successful cranioplasties and TE can play a safe and effective role in selected cases.

Stable Aggregates in the Dynamics of a Competing Population

C. H. Yeung,K. Y. Michael Wong,Y. P. Ma 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.1I

We propose a dynamical model of a competing population whose agents have a tendency to balance their decisions in time. The model is applicable to financial markets in which the agents trade with finite capital or to other multiagent systems, such as routers in communication networks attempting to transmit multiclass traffic in a fair way. We find an oscillatory behavior of the model which is explainable by the segregation of agents into two groups. Each group remains winning over epochs. The aggregation of smart agents is able to explain the lifetime distribution of epochs to 8 decades of probability.

Cascades of Dynamical Transitions in an Adaptive Population

H. M. Yang,K. Y. Michael Wong,Y. S. Ting 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.1I

In an adaptive population that models .nancial markets and distributed control, we consider how the dynamics depends on the diversity of the agents' initial preferences of strategies. When the diversity decreases, more agents tend to adapt their strategies together. This change in the environment results in dynamical transitions from vanishing to non-vanishing step sizes. When the diversity decreases further, we .nd a cascade of dynamical transitions for the dierent signal dimensions, which is supported by good agreement between simulations and theory. Besides, the signal of the largest step size at steady state is likely to be the initial signal.c

Two-Dimensional IR Spectroscopy of Protein Dynamics Using Two Vibrational Labels: A Site-Specific Genetically Encoded Unnatural Amino Acid and an Active Site Ligand

Thielges, Megan C.,Axup, Jun Y.,Wong, Daryl,Lee, Hyun Soo,Chung, Jean K.,Schultz, Peter G.,Fayer, Michael D. American Chemical Society 2011 The journal of physical chemistry. B, Condensed ma Vol.115 No.38

<P>Protein dynamics and interactions in myoglobin (Mb) were characterized via two vibrational dynamics labels (VDLs): a genetically incorporated site-specific azide (Az) bearing unnatural amino acid (AzPhe43) and an active site CO ligand. The Az-labeled protein was studied using ultrafast two-dimensional infrared (2D IR) vibrational echo spectroscopy. CO bound at the active site of the heme serves as a second VDL located nearby. Therefore, it was possible to use Fourier transform infrared (FT-IR) and 2D IR spectroscopic experiments on the Az in unligated Mb and in Mb bound to CO (MbAzCO) and on the CO in MbCO and MbAzCO to investigate the environment and motions of different states of one protein from the perspective of two spectrally resolved VDLs. A very broad bandwidth 2D IR spectrum, encompassing both the Az and CO spectral regions, found no evidence of direct coupling between the two VDLs. In MbAzCO, both VDLs reported similar time scale motions: very fast homogeneous dynamics, fast, ∼1 ps dynamics, and dynamics on a much slower time scale. Therefore, each VDL reports independently on the protein dynamics and interactions, and the measured dynamics are reflective of the protein motions rather than intrinsic to the chemical nature of the VDL. The AzPhe VDL also permitted study of oxidized Mb dynamics, which could not be accessed previously with 2D IR spectroscopy. The experiments demonstrate that the combined application of 2D IR spectroscopy and site-specific incorporation of VDLs can provide information on dynamics, structure, and interactions at virtually any site throughout any protein.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2011/jpcbfk.2011.115.issue-38/jp206986v/production/images/medium/jp-2011-06986v_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp206986v'>ACS Electronic Supporting Info</A></P>