330 research outputs found
Fragile boundaries of tailored surface codes
Biased noise is common in physical qubits, and tailoring a quantum code to
the bias by locally modifying stabilizers or changing boundary conditions has
been shown to greatly increase error correction thresholds. In this work, we
explore the challenges of using a specific tailored code, the XY surface code,
for fault-tolerant quantum computation. We introduce efficient and
fault-tolerant decoders, belief-matching and belief-find, which exploit
correlated hyperedge fault mechanisms present in circuit-level noise. Using
belief-matching, we find that the XY surface code has a higher threshold and
lower overhead than the square CSS surface code for moderately biased noise.
However, the rectangular CSS surface code has a lower qubit overhead than the
XY surface code when below threshold. We identify a contributor to the reduced
performance that we call fragile boundary errors. These are string-like errors
that can occur along spatial or temporal boundaries in planar architectures or
during logical state preparation and measurement. While we make partial
progress towards mitigating these errors by deforming the boundaries of the XY
surface code, our work suggests that fragility could remain a significant
obstacle, even for other tailored codes. We expect that our decoders will have
other uses; belief-find has an almost-linear running time, and we show that it
increases the threshold of the surface code to 0.937(2)% in the presence of
circuit-level depolarising noise, compared to 0.817(5)% for the more
computationally expensive minimum-weight perfect matching decoder.Comment: 16 pages, 17 figure
Metabolism of ticagrelor in patients with acute coronary syndromes.
© The Author(s) 2018Ticagrelor is a state-of-the-art antiplatelet agent used for the treatment of patients with acute coronary syndromes (ACS). Unlike remaining oral P2Y12 receptor inhibitors ticagrelor does not require metabolic activation to exert its antiplatelet action. Still, ticagrelor is extensively metabolized by hepatic CYP3A enzymes, and AR-C124910XX is its only active metabolite. A post hoc analysis of patient-level (n = 117) pharmacokinetic data pooled from two prospective studies was performed to identify clinical characteristics affecting the degree of AR-C124910XX formation during the first six hours after 180 mg ticagrelor loading dose in the setting of ACS. Both linear and multiple regression analyses indicated that ACS patients presenting with ST-elevation myocardial infarction or suffering from diabetes mellitus are more likely to have decreased rate of ticagrelor metabolism during the acute phase of ACS. Administration of morphine during ACS was found to negatively influence transformation of ticagrelor into AR-C124910XX when assessed with linear regression analysis, but not with multiple regression analysis. On the other hand, smoking appears to increase the degree of ticagrelor transformation in ACS patients. Mechanisms underlying our findings and their clinical significance warrant further research.Peer reviewedFinal Published versio
Who approves/pays for additional monitoring?
Major considerations in the provision of healthcare are availability, affordability, accessibility, and appropriateness, especially in the setting of heart failure where disease burden is growing, developments have been rapid and newer biomarkers, diagnostic and imaging techniques, monitoring systems, devices, procedures, and drugs have all been developed in a relatively short period of time. Many monitoring and diagnostic systems have been developed but the disproportionate cost of conducting trials of their effectiveness has limited their uptake. There are added complexities, in that the utilization of doctors for the supervision of the monitoring results may be optimal in one setting and not in another because of differences in the characteristics of organization of healthcare provision, making even interpretation of the trials we have had, still difficult to interpret. New technologies are continuously changing the approach to healthcare and will reshape the structure of the healthcare systems in the future. Mobile technologies can empower patients and carers by giving them more control over their health and social care needs and reducing their dependence on healthcare professionals for monitoring their health, but a significant problem is the integration of the multitude of monitored parameters with clinical data and the recognition of intervention thresholds. Digital technology can help, but we need to prove its cost/efficacy and how it will be paid for. Governments in many European countries and worldwide are trying to establish frameworks that promote the convergence of standards and regulations for telemedicine solutions and yet simultaneously health authorities are closely scrutinizing healthcare spending, with the objective of reducing and optimizing expenditure in the provision of health services. There are multiple factors to be considered for the reimbursement models associated with the implementation of physiological monitoring yet it remains a challenge in cash-strapped health systems
INVESTIGATION OF THE TRANSMISSION AND STOPPING OF LIGHT IONS PASSING THROUGH A PLASMA TARGET
Transmission and energy losses of 2 MeV/u Carbon and Sulphur beams passing through a plasma target, have been extensively investigated. A hydrogen plasma ignited by an electrical discharge was coupled to the Orsay Tandem beam accelerator. Fluctuations in beam transmission have been observed and attributed to a magnetic focusing effect generated during the plasma evolution. Energy loss measurements were performed on the basis of time of flight techniques and indicate an enhanced stopping power of the plasma relative to its cold matter equivalent
Low-molecular-weight heparins vs. unfractionated heparin in the setting of percutaneous coronary intervention for ST-elevation myocardial infarction: a meta-analysis
Summary. Background: The aim of the current study was to
perform two separate meta-analyses of available studies
comparing low-molecular-weight heparins (LMWHs) vs.
unfractionated heparin (UFH) in ST-elevation myocardial
infarction (STEMI) patients treated (i) with primary percutaneous
coronary intervention (pPCI) or (ii) with PCI after
thrombolysis. Methods: All-cause mortality was the prespecified
primary endpoint and major bleeding complications
were recorded as the secondary endpoints. Relative risk (RR)
with a 95%confidence interval (CI) and absolute risk reduction
(ARR) were chosen as the effect measure. Results: Ten studies
comprising 16 286 patients were included. The median followup
was 2 months for the primary endpoint. Among LMWHs,
enoxaparin was the compound most frequently used. In the
pPCI group, LMWHs were associated with a reduction in
mortality [RR (95% CI) = 0.51 (0.41–0.64), P < 0.001,
ARR = 3%] and major bleeding [RR (95% CI) = 0.68
(0.49–0.94), P = 0.02, ARR = 2.0%] as compared with
UFH. Conversely, no clear evidence of benefits with LWMHs
was observed in the PCI group after thrombolysis. Metaregression
showed that patients with a higher baseline risk had
greater benefits from LMWHs (r = 0.72, P = 0.02). Conclusions:
LMWHs were associated with greater efficacy and safety
than UFH in STEMI patients treated with pPCI, with a
significant relationship between risk profile and clinical benefits.
Based on this meta-analysis, LMWHs may be considered as a
preferred anticoagulant among STEMI patients undergoing
pPCI
The Pan-STARRS Moving Object Processing System
We describe the Pan-STARRS Moving Object Processing System (MOPS), a modern
software package that produces automatic asteroid discoveries and
identifications from catalogs of transient detections from next-generation
astronomical survey telescopes. MOPS achieves > 99.5% efficiency in producing
orbits from a synthetic but realistic population of asteroids whose
measurements were simulated for a Pan-STARRS4-class telescope. Additionally,
using a non-physical grid population, we demonstrate that MOPS can detect
populations of currently unknown objects such as interstellar asteroids.
MOPS has been adapted successfully to the prototype Pan-STARRS1 telescope
despite differences in expected false detection rates, fill-factor loss and
relatively sparse observing cadence compared to a hypothetical Pan-STARRS4
telescope and survey. MOPS remains >99.5% efficient at detecting objects on a
single night but drops to 80% efficiency at producing orbits for objects
detected on multiple nights. This loss is primarily due to configurable MOPS
processing limits that are not yet tuned for the Pan-STARRS1 mission.
The core MOPS software package is the product of more than 15 person-years of
software development and incorporates countless additional years of effort in
third-party software to perform lower-level functions such as spatial searching
or orbit determination. We describe the high-level design of MOPS and essential
subcomponents, the suitability of MOPS for other survey programs, and suggest a
road map for future MOPS development.Comment: 57 Pages, 26 Figures, 13 Table
Demonstrating a long-coherence dual-rail erasure qubit using tunable transmons
Quantum error correction with erasure qubits promises significant advantages
over standard error correction due to favorable thresholds for erasure errors.
To realize this advantage in practice requires a qubit for which nearly all
errors are such erasure errors, and the ability to check for erasure errors
without dephasing the qubit. We experimentally demonstrate that a "dual-rail
qubit" consisting of a pair of resonantly-coupled transmons can form a highly
coherent erasure qubit, where the erasure error rate is given by the transmon
but for which residual dephasing is strongly suppressed, leading to
millisecond-scale coherence within the qubit subspace. We show that
single-qubit gates are limited primarily by erasure errors, with erasure
probability per gate while the
residual errors are times lower. We further demonstrate mid-circuit
detection of erasure errors while introducing dephasing error per
check. Finally, we show that the suppression of transmon noise allows this
dual-rail qubit to preserve high coherence over a broad tunable operating
range, offering an improved capacity to avoid frequency collisions. This work
establishes transmon-based dual-rail qubits as an attractive building block for
hardware-efficient quantum error correction.Comment: 8+12 pages, 16 figure
Computing Covers under Substring Consistent Equivalence Relations
Covers are a kind of quasiperiodicity in strings. A string is a cover of
another string if any position of is inside some occurrence of in
. The shortest and longest cover arrays of have the lengths of the
shortest and longest covers of each prefix of , respectively. The literature
has proposed linear-time algorithms computing longest and shortest cover arrays
taking border arrays as input. An equivalence relation over strings
is called a substring consistent equivalence relation (SCER) iff
implies (1) and (2) for all . In this paper, we generalize the notion of covers for SCERs and prove
that existing algorithms to compute the shortest cover array and the longest
cover array of a string under the identity relation will work for any SCERs
taking the accordingly generalized border arrays.Comment: 16 page
- …