Quantum control and process tomography of a semiconductor quantum dot hybrid qubit

The similarities between gated quantum dots and the transistors in modern microelectronics - in fabrication methods, physical structure, and voltage scales for manipulation - have led to great interest in the development of quantum bits (qubits) in semiconductor quantum dots. While quantum dot spin qubits have demonstrated long coherence times, their manipulation is often slower than desired for important future applications, such as factoring. Further, scalability and manufacturability are enhanced when qubits are as simple as possible. Previous work has increased the speed of spin qubit rotations by making use of integrated micromagnets, dynamic pumping of nuclear spins, or the addition of a third quantum dot. Here we demonstrate a new qubit that offers both simplicity - it requires no special preparation and lives in a double quantum dot with no added complexity - and is very fast: we demonstrate full control on the Bloch sphere with $\pi$-rotation times less than 100 ps in two orthogonal directions. We report full process tomography, extracting high fidelities equal to or greater than 85% for X-rotations and 94% for Z-rotations. We discuss a path forward to fidelities better than the threshold for quantum error correction.Comment: 6 pages, excluding Appendi

Explaining Myanmar's Regime Transition: The Periphery is Central

In 2010, Myanmar (Burma) held its first elections after 22 years of direct military rule. Few compelling explanations for this regime transition have emerged. This article critiques popular accounts and potential explanations generated by theories of authoritarian ‘regime breakdown’ and ‘regime maintenance’. It returns instead to the classical literature on military intervention and withdrawal. Military regimes, when not terminated by internal factionalism or external unrest, typically liberalise once they feel they have sufficiently addressed the crises that prompted their seizure of power. This was the case in Myanmar. The military intervened for fear that political unrest and ethnic-minority separatist insurgencies would destroy Myanmar’s always-fragile territorial integrity and sovereignty. Far from suddenly liberalising in 2010, the regime sought to create a ‘disciplined democracy’ to safeguard its preferred social and political order twice before, but was thwarted by societal opposition. Its success in 2010 stemmed from a strategy of coercive state-building and economic incorporation via ‘ceasefire capitalism’, which weakened and co-opted much of the opposition. Having altered the balance of forces in its favour, the regime felt sufficiently confident to impose its preferred settlement. However, the transition neither reflected total ‘victory’ for the military nor secured a genuine or lasting peace

Mechanisims of asthma and allergic disease – 1086. Bacteria-derived extracellular vesicles as an important causative agent for asthma and COPD

Background Many bacterial components in indoor dust can evoke inflammatory pulmonary diseases. Bacteria secrete nanometer-sized vesicles into the extracellular milieu, but it remains to be determined whether bacteria-derived extracellular vesicles in indoor dust are pathophysiologically related to inflammatory pulmonary diseases. We evaluated whether extracellular vesicles (EV) in indoor air are causally related to the pathogenesis of asthma and/or emphysema. Methods EV were prepared by sequential ultrafiltration and ultracentrifugation from indoor dust collected from a bed. Innate and adaptive immune responses were evaluated after once or 4 weeks airway exposure of EV, respectively. Results Vesicles 50-200 nm in diameter were present (102.5 microgram [based on protein concentration]/g dust) in indoor dust, and inhalation of 1 microgram of these vesicles for 4 weeks caused neutrophilic pulmonary inflammation. Additionally, polymyxin B (an antagonist of endotoxin, a cell wall component of Gram-negative bacteria) reversed the inflammation induced by the dust EV. Indoor dust harbors Esherichia coli-derived vesicles; airway exposure to the vesicles for 4 weeks induced neutrophilic inflammation and emphysema, which were partially eliminated by the absence of IFN-gamma or IL-17. Interestingly, serum dust EV-reactive IgG1 levels were significantly higher in atopic children with asthma than in atopic healthy children and those with rhinitis or dermatitis. Moreover, serum dust EV-reactive IgG1 levels were also elevated in adult asthma or COPD patients than in healthy controls. Conclusions EV in indoor dust, especially derived from Gram-negative bacteria, appear to be an important causative agent in the pathogenesis of asthma and/or emphysema

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

Comprehensive analysis of chromothripsis in 2,658 human cancers using whole-genome sequencing

Chromothripsis is a mutational phenomenon characterized by massive, clustered genomic rearrangements that occurs in cancer and other diseases. Recent studies in selected cancer types have suggested that chromothripsis may be more common than initially inferred from low-resolution copy-number data. Here, as part of the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA), we analyze patterns of chromothripsis across 2,658 tumors from 38 cancer types using whole-genome sequencing data. We find that chromothripsis events are pervasive across cancers, with a frequency of more than 50% in several cancer types. Whereas canonical chromothripsis profiles display oscillations between two copy-number states, a considerable fraction of events involve multiple chromosomes and additional structural alterations. In addition to non-homologous end joining, we detect signatures of replication-associated processes and templated insertions. Chromothripsis contributes to oncogene amplification and to inactivation of genes such as mismatch-repair-related genes. These findings show that chromothripsis is a major process that drives genome evolution in human cancer

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

The Pitfalls of a State in Transition Myanmar 1974-2000

Ph.DDOCTOR OF PHILOSOPH

The CPF scheme and its economic implications

The Central Provident Fund (CPF) was established on July 1, 1955. It is essentially a compulsory savings fund to which both the employees and their employers contribute. The main intent of the CPF is to make funds available to employees when they reach retirement or cannot continue in employment due to physical or mental incapacity.BUSINES

Title Datalogging in Singapore schools: Supporting effective implementations Author(s) Datalogging in Singapore Schools: Supporting effective implementations Datalogging in Singapore Schools: Supporting effective implementations

Abstract This paper reports the findings of a national survey on the use of dataloggers in secondary schools (Grades 7-10) and junior colleges (Grades 11-12). In particular, it explores the types of learning activities that teachers conduct using dataloggers, the support structures they deem necessary, and the difficulties they face. Out of the 593 respondents, 394 (67%) had used dataloggers in the last two years, mainly in demonstrations and set experiments. The three most important support structures included: supportive laboratory technicians, training on the use of dataloggers, and instructional material on how to use dataloggers within the curriculum. The difficulties which deterred the respondents from using dataloggers included the logistics and time taken to set up datalogging equipment and activities, insufficient numbers of computer workstations, and the mishandling of equipment by students leading to equipment malfunctions. To expand the use of dataloggers in school, the respondents suggest that dedicated laboratories be set up for datalogging activities, more curricular material to support datalogging be prepared, more familiarisation courses be run for teachers and laboratory technicians and, in particular, how dataloggers fit within an inquiry science learning approach

Datalogging in Singapore schools: supporting effective implementations

This paper reports the findings of a national survey on the use of dataloggers in secondary schools (grades 7–10) and junior colleges (grades 11–12). In particular, it explores the types of learning activities that teachers conduct using dataloggers, the support structures they deem necessary and the difficulties they face. Of the 593 respondents, 394 (67%) had used dataloggers in the last two years, mainly in demonstrations and set experiments. The three most important support structures included: supportive laboratory technicians, training on the use of dataloggers, and instructional material on how to use dataloggers within the curriculum. The difficulties which deterred the respondents from using dataloggers included the logistics and time taken to set up datalogging equipment and activities, insufficient numbers of computer workstations, and the mishandling of equipment by students, leading to equipment malfunctions. To expand the use of dataloggers in school, the respondents suggest that dedicated laboratories be set up for datalogging activities, more curricular material to support datalogging be prepared, more familiarisation courses be run for teachers and laboratory technicians and, in particular, how dataloggers fit within an inquiry science learning approach.17 page(s