2,224 research outputs found
Origin of the anomalies: the modified Heisenberg equation
The origin of the anomalies is analyzed. It is shown that they are due to the
fact that the generators of the symmetry do not leave invariant the domain of
definition of the Hamiltonian and then a term, normally forgotten in the
Heisenberg equation, gives an extra contribution responsible for the non
conservation of the charges. This explanation is equivalent to that of the
Fujikawa in the path integral formalism. Finally, this approach is applied to
the conformal symmetry breaking in two-dimensional quantum mechanics.Comment: 7 pages, LaTe
Multiplexed Readout of Transmon Qubits with Josephson Bifurcation Amplifiers
Achieving individual qubit readout is a major challenge in the development of
scalable superconducting quantum processors. We have implemented the
multiplexed readout of a four transmon qubit circuit using non-linear
resonators operated as Josephson bifurcation amplifiers. We demonstrate the
simultaneous measurement of Rabi oscillations of the four transmons. We find
that multiplexed Josephson bifurcation is a high-fidelity readout method, the
scalability of which is not limited by the need of a large bandwidth nearly
quantum-limited amplifier as is the case with linear readout resonators.Comment: 7 pages, 6 figures, and 31 reference
Improving Public Services by Mining Citizen Feedback: An Application of Natural Language Processing
Research on user satisfaction has increased substantially in recent years. To date, most studies have tested the significance of predefined factors thought to influence user satisfaction, with no scalable means of verifying the validity of their assumptions. Digital technology has created new methods of collecting user feedback where service users post comments. As topic models can analyse large volumes of feedback, they have been proposed as a feasible approach to aggregating user opinions. This novel approach has been applied to process reviews of primary care practices in England. Findings from an analysis of more than 200,000 reviews show that the quality of interactions with staff and bureaucratic exigencies are the key drivers of user satisfaction. In addition, patient satisfaction is strongly influenced by factors that are not measured by state‐of‐the‐art patient surveys. These results highlight the potential benefits of text mining and machine learning for public administration
Multi-mode storage and retrieval of microwave fields in a spin ensemble
A quantum memory at microwave frequencies, able to store the state of
multiple superconducting qubits for long times, is a key element for quantum
information processing. Electronic and nuclear spins are natural candidates for
the storage medium as their coherence time can be well above one second.
Benefiting from these long coherence times requires to apply the refocusing
techniques used in magnetic resonance, a major challenge in the context of
hybrid quantum circuits. Here we report the first implementation of such a
scheme, using ensembles of nitrogen-vacancy (NV) centres in diamond coupled to
a superconducting resonator, in a setup compatible with superconducting qubit
technology. We implement the active reset of the NV spins into their ground
state by optical pumping and their refocusing by Hahn echo sequences. This
enables the storage of multiple microwave pulses at the picoWatt level and
their retrieval after up to s, a three orders of magnitude improvement
compared to previous experiments.Comment: 8 pages, 5 figures + Supplementary information (text and 6 figures
Density of states in a superconductor carrying a supercurrent
We have measured the tunneling density of states (DOS) in a superconductor
carrying a supercurrent or exposed to an external magnetic field. The pair
correlations are weakened by the supercurrent, leading to a modification of the
DOS and to a reduction of the gap. As predicted by the theory of
superconductivity in diffusive metals, we find that this effect is similar to
that of an external magnetic field.Comment: To be published in Physical Review Letter
Coulomb charging energy for arbitrary tunneling strength
The Coulomb energy of a small metallic island coupled to an electrode by a
tunnel junction is investigated. We employ Monte Carlo simulations to determine
the effective charging energy for arbitrary tunneling strength. For small
tunneling conductance, the data agree with analytical results based on a
perturbative treatment of electron tunneling, while for very strong tunneling
recent semiclassical results for large conductance are approached. The data
allow for an identification of the range of validity of various analytical
predictions.Comment: 4 pages REVTeX, incl 3 figures, to appear in Europhys.Let
Transcription factor LSF-DNMT1 complex dissociation by FQI1 leads to aberrant DNA methylation and gene expression
The transcription factor LSF is highly expressed in hepatocellular carcinoma (HCC) and promotes oncogenesis. Factor quinolinone inhibitor 1 (FQI1), inhibits LSF DNA-binding activity and exerts anti-proliferative activity. Here, we show that LSF binds directly to the maintenance DNA (cytosine-5) methyltransferase 1 (DNMT1) and its accessory protein UHRF1 both in vivo and in vitro. Binding of LSF to DNMT1 stimulated DNMT1 activity and FQI1 negated the methyltransferase activation. Addition of FQI1 to the cell culture disrupted LSF bound DNMT1 and UHRF1 complexes, resulting in global aberrant CpG methylation. Differentially methylated regions (DMR) containing at least 3 CpGs, were significantly altered by FQI1 compared to control cells. The DMRs were mostly concentrated in CpG islands, proximal to transcription start sites, and in introns and known genes. These DMRs represented both hypo and hypermethylation, correlating with altered gene expression. FQI1 treatment elicits a cascade of effects promoting altered cell cycle progression. These findings demonstrate a novel mechanism of FQI1 mediated alteration of the epigenome by DNMT1-LSF complex disruption, leading to aberrant DNA methylation and gene expression.We would like to thank Drs. Donald Comb, Rich Roberts, William Jack and Clotilde Carlow at New England Biolabs Inc. for research support and encouragement. The authors thank Dr. Lauren Brown (Boston University Center for Molecular Discovery) for the preparation of FQI1. UH research on this project was supported by Ignition Awards from Boston University and a Johnson & Johnson Clinical Innovator's Award through Boston University. SES research is supported by the NIH (P50 GM067041 & R24 GM111625). Research performed by HGC was partly a requirement for the MCBB graduate program at Boston University and supported by NEB. (Boston University; Johnson & Johnson Clinical Innovator's Award through Boston University; P50 GM067041 - NIH; R24 GM111625 - NIH; NEB)Published versio
Food healthy knowledge, attitudes and practices: Survey of the general public and food handlers
AbstractModifying the energy content of foods, particularly foods eaten away from home, is important in addressing the obesity epidemic. Food handlers in the restaurant industry are uniquely placed to influence the provision of reduced-calorie foods, but little is known about their opinions on this issue. The objectives of the present study were to determine the general public and food handlers׳ knowledge and opinions, issues and barriers related to providing these items on the menu, and about the influence of the calorie content of restaurant items on customer intake. The food handlers surveyed had a significantly lower food science knowledge score than the general public. There was significant difference between the scores of food handlers and general public (t=3.5108, df=177.743, P-value=0.0005). The majority of respondents ranked taste as the most influential factor in the success of reduced-calorie items (p<0.0028). The results of this survey indicate that opportunities exist for reducing the energy content of restaurant items. Ongoing collaboration is needed between food handlers and public health professionals to ensure that appealing reduced-calorie menu items are more widely available in restaurants and that research is directed towards effective ways to develop and promote these items
Changes in gait during constant pace treadmill running.
Treadmills are often used by runners when weather conditions are adverse or a specific training effect is desired. Athletes might respond to fatigue differently when running on a treadmill compared with overground conditions, where pace is typically more variable. The purpose of this study was to measure changes in gait parameters over the course of a 10-km treadmill run. Fifteen male competitive runners ran at a constant pace for 10 km at 103% of season's best time on an instrumented treadmill with in-dwelling force plates, and data were analyzed at 5 distances. Kinematic data were derived from high-speed videography and results compared between the early and late stages. Before halfway, step length increased and cadence decreased, whereas during the latter stages, there were significant decreases in impulse and maximum force. Contact time decreased and flight time increased continually, but otherwise most gait variables did not change. The changes in contact and flight times suggested that athletes altered their gait so that more time was spent airborne to allow the treadmill to pass under them. In general, however, the runners maintained their techniques throughout the run. Constant pace treadmill running might therefore be useful with the aim of running for a particular distance and speed with a consistent technique unaffected by factors such as gradient or fatigue. However, the increase in flight time might have aided the runners because of the nature of treadmill running, and athletes and coaches should note that this training effect is impractical during overground running
- …