30 research outputs found

    Parallel assembly of arbitrary defect-free atom arrays with a multi-tweezer algorithm

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    Defect-free atom arrays are an important precursor for quantum information processing and quantum simulation. Yet, large-scale defect-free atom arrays remain challenging to realize, due to the losses encountered when rearranging stochastically loaded atoms to achieve a desired target array. Here, we demonstrate a novel parallel rearrangement algorithm that uses multiple mobile tweezers to independently sort and compress atom arrays in a way that naturally avoids atom collisions. For a high degree of parallelism, the required number of moves scales as N^0.5 with respect to the target array size N, as opposed to existing single-tweezer algorithms that scale as N or larger. We further determine the optimal degree of parallelism to be a balance between the algorithmic speedup and intermodulation effects. The defect-free probability for a 225-atom array is demonstrated to be as high as 33(1)% in a room temperature setup after multiple cycles of rearrangement. The algorithm presented here can be implemented for any target array geometry with an underlying periodic structure

    Predictors of acute neurological complication following tetralogy of Fallot operation in Serdang Hospital, Malaysia

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    Background: The long waiting time for Tetralogy of Fallot (TOF) operation may potentially increase the risk of hypoxic insult. Therefore, the objective of this study is to determine the frequency of acute neurological complications following primary TOF repair and to identify the peri-operative risk factors and predictors for the neurological sequelae. Methods: A retrospective review of the medical and surgical notes of 68 patients who underwent TOF repair in Hospital Serdang, from January 2013 to December 2017 was done. Univariate and multivariate analyses of demographics and perioperative clinical data were performed to determine the risk for the development of acute neurological complications (ANC) among these patients. Results: ANC was reported in 13 cases (19.1%) with delirium being the most common manifestation (10/68, 14.7%), followed by seizures in 4 (5.9%) and abnormal movements in two patients (2.9%). Univariate analyses showed that the presence of right ventricular (RV) dysfunction, prolonged duration of inotropic support (≥7 days), prolonged duration of mechanical ventilation (≥7 days), longer length of ICU stays (≥7 days), and longer length of hospital stay (≥14 days), were significantly associated with the presence of ANCs (p0.05). The predictors for the development of postoperative delirium were pre-operative oxygen saturation less than 75% (Odds Ratio, OR=16.90, 95% Confidence Interval, 95%CI:1.36, 209.71) and duration of ventilation of more than 7 days (OR=13.20, 95%CI: 1.20, 144.98). Conclusion: ANC following TOF repair were significantly higher in patients with RV dysfunction, in those who required a longer duration of inotropic support, mechanical ventilation, ICU and hospital stay. Low pre-operative oxygen saturation and prolonged mechanical ventilation requirement were predictors for delirium which was the commonest neurological complications observed in this study. Hence, routine screening for delirium using an objective assessment tool should be performed on these high-risk patients to enable accurate diagnosis and early intervention to improve the overall outcome of TOF surgery in this country

    Multiancestry analysis of the HLA locus in Alzheimer’s and Parkinson’s diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes

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    Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinson’s disease (PD) and Alzheimer’s disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased Aβ42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues

    THE EPIDEMIOLOGY AND CONTROL OF HAND, FOOT AND MOUTH DISEASE

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    Ph.DDOCTOR OF PHILOSOPH

    Analysis of the Fama and French three factor model on ASEAN markets.

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    The Fama and French three factor model introduced two variables (size and book to market value) to capture the cross-sectional variations of stock returns in the US market. This paper seeks to extend this finding to the ASEAN markets, namely the Singapore, Malaysia, Thailand and The Philippines equity markets. We make comparisons to the CAPM model and identify a fourth Liquidity Premium factor to investigate the effects on the explanatory powers of the three factor model. We document that while the US markets possess size and PB effects, we fail to observe similar phenomena in ASEAN markets. Also, time series and cross-sectional regression tests show that the CAPM, the Fama and French three factor model and the Four Factor Model have limited power to explain the excess equity return in ASEAN markets.BUSINES

    Recent Progress in Energy-Driven Water Splitting

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    Hydrogen is readily obtained from renewable and non-renewable resources via water splitting by using thermal, electrical, photonic and biochemical energy. The major hydrogen production is generated from thermal energy through steam reforming/gasification of fossil fuel. As the commonly used non-renewable resources will be depleted in the long run, there is great demand to utilize renewable energy resources for hydrogen production. Most of the renewable resources may be used to produce electricity for driving water splitting while challenges remain to improve cost-effectiveness. As the most abundant energy resource, the direct conversion of solar energy to hydrogen is considered the most sustainable energy production method without causing pollutions to the environment. In overall, this review briefly summarizes thermolytic, electrolytic, photolytic and biolytic water splitting. It highlights photonic and electrical driven water splitting together with photovoltaic-integrated solar-driven water electrolysis.Published versio

    Simulating forest fire spread and fire-fighting using cellular automata

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    In response to the transboundary haze problem in Southeast Asia, a physical model is adopted to simulate the spread and extinguishing of fire. This study is done in the context of Dumai, Indonesia, as it is one of the areas that significantly contribute to the haze problem. This model aims to provide perspectives on the persistence of forest fires despite fire-fighting efforts. While existing models using Huygens’ principle of wave propagation allow an understanding of the natural spread of fire, our model applies cellular automata to predict and analyse the effects of fire-fighting intervention strategies, with the spatial and propagation dynamics of fire considered. Cellular automata is an active area of research among physicists, and is widely used by chemists and biologists to model many types of natural phenomena. We note similarities between our model predictions and observations of real-world phenomena. Analyses on the factors that affect the spread of fire are presented, in order to understand which ones are dominant in differing situations. This provides insights on optimum conditions for fire-fighting efforts, and suggests guidelines that may be considered for fire control in future forest fires
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