153 research outputs found
Dephasing of Electrons on Helium by Collisions with Gas Atoms
The damping of quantum effects in the transport properties of electrons
deposited on a surface of liquid helium is studied. It is found that due to
vertical motion of the helium vapour atoms the interference of paths of
duration is damped by a factor . An expression is
derived for the weak-localization lineshape in the case that damping occurs by
a combination of processes with this type of cubic exponential damping and
processes with a simple exponential damping factor.Comment: 7 pages, 2 figures, Revte
Invariance of Charge of Laughlin Quasiparticles
A Quantum Antidot electrometer has been used in the first direct observation
of the fractionally quantized electric charge. In this paper we report
experiments performed on the integer i = 1, 2 and fractional f = 1/3 quantum
Hall plateaus extending over a filling factor range of at least 27%. We find
the charge of the Laughlin quasiparticles to be invariantly e/3, with standard
deviation of 1.2% and absolute accuracy of 4%, independent of filling,
tunneling current, and temperature.Comment: 4 pages, 5 fig
Magnetoresistance of nondegenerate quantum electron channels formed on the surface of superfluid helium
Transport properties of quasi-one-dimensional nondegenerate quantum wires
formed on the surface of liquid helium in the presence of a normal magnetic
field are studied using the momentum balance equation method and the memory
function formalism. The interaction with both kinds of scatterers available
(vapor atoms and capillary wave quanta) is considered. We show that unlike
classical wires, quantum nondegenerate channels exhibit strong
magnetoresistance which increases with lowering the temperature.Comment: 8 pages, 7 figure
Calcaneal nonunion: three cases and a review of the literature
The long-term follow-up of intra-articular calcaneal fractures is often accompanied by complications. Frequently occurring are arthrosis, arthrofibrosis of the subtalar joint, and malunion. Uncommon is the calcaneal nonunion. A total of three cases is presented in this report, including a review of the literature. The occurrence of a nonunion appears to be more common after conservative treatment, but the pathophysiology remains unclear, however smoking may play a role
Resistance fluctuations and Aharonov-Bohm-type oscillations in antidot arrays in the quantum Hall regime
Resistance fluctuation phenomenon in antidot lattices in the quantum Hall
regime are studied. Magnetoresistance of finite antidot array systems in the
quantum Hall plateau transition regime exhibits two types of oscillatory
effect. One is the aperiodic resistance fluctuations (RFs) and the other is the
Aharonov-Bohm (AB)-type oscillations. Their dependences on the magnetic field
and the gate voltage are quite distinct. While the aperiodic RFs are attributed
to the complex evolution of the conducting network of compressible channels,
the AB-type oscillations are interpreted in terms of edge states formed around
individual antidots. The self-consistent screening effect is important for the
both phenomenon, whereas, the single electron charging effect plays a minor
role in the present case.Comment: 5 pages, 4 figure
Global mortality and readmission rates following COPD exacerbation-related hospitalisation: a meta-analysis of 65 945 individual patients
\ua9 2024, European Respiratory Society. All rights reserved.Background Exacerbations of COPD (ECOPD) have a major impact on patients and healthcare systems across the world. Precise estimates of the global burden of ECOPD on mortality and hospital readmission are needed to inform policy makers and aid preventive strategies to mitigate this burden. The aims of the present study were to explore global in-hospital mortality, post-discharge mortality and hospital readmission rates after ECOPD-related hospitalisation using an individual patient data meta-analysis (IPDMA) design. Methods A systematic review was performed identifying studies that reported in-hospital mortality, postdischarge mortality and hospital readmission rates following ECOPD-related hospitalisation. Data analyses were conducted using a one-stage random-effects meta-analysis model. This study was conducted and reported in accordance with the PRISMA-IPD statement. Results Data of 65 945 individual patients with COPD were analysed. The pooled in-hospital mortality rate was 6.2%, pooled 30-, 90- and 365-day post-discharge mortality rates were 1.8%, 5.5% and 10.9%, respectively, and pooled 30-, 90- and 365-day hospital readmission rates were 7.1%, 12.6% and 32.1%, respectively, with noticeable variability between studies and countries. Strongest predictors of mortality and hospital readmission included noninvasive mechanical ventilation and a history of two or more ECOPD-related hospitalisation
Volatile profile and physical, chemical, and biochemical changes in fresh cut watermelon during storage
Potential Role of Stabilized Criegee Radicals in Sulfuric Acid Production in a High Biogenic VOC Environment
We present field observations made in June 2011 downwind of Dallas-Fort Worth, TX, and evaluate the role of stabilized Criegee radicals (sCIs) in gaseous sulfuric acid (H2SO4) production. Zero-dimensional model calculations show that sCI from biogenic volatile organic compounds composed the majority of the sCIs. The main uncertainty associated with an evaluation of H2SO4 production from the sCI reaction channel is the lack of experimentally determined reaction rates for sCIs formed from isoprene ozonolysis with SO2 along with systematic discrepancies in experimentally derived reaction rates between other sCIs and SO2 and water vapor. In general, the maximum of H2SO4 production from the sCI channel is found in the late afternoon as ozone increases toward the late afternoon. The sCI channel, however, contributes minor H2SO4 production compared with the conventional OH channel in the mid-day. Finally, the production and the loss rates of H2SO4 are compared. The application of the recommended mass accommodation coefficient causes significant overestimation of H2SO4 loss rates compared with H2SO4 production rates. However, the application of a lower experimental value for the mass accommodation coefficient provides good agreement between the loss and production rates of H2SO4. The results suggest that the recommended coefficient for the H2O surface may not be suitable for this relatively dry environment
ADVANCE integrated group intervention to address both substance use and intimate partner abuse perpetration by men in substance use treatment: a feasibility randomised controlled trial
Background: Substance use is a risk factor for intimate partner abuse (IPA) perpetration. Delivering perpetrator
interventions concurrently with substance use treatment shows promise.
Methods: The feasibility of conducting an efficacy and cost-effectiveness trial of the ADVANCE 16-week
intervention to reduce IPA by men in substance use treatment was explored. A multicentre, parallel group
individually randomised controlled feasibility trial and formative evaluation was conducted. Over three temporal
cycles, 104 men who had perpetrated IPA towards a female (ex) partner in the past year were randomly allocated
to receive the ADVANCE intervention + substance use treatment as usual (TAU) (n = 54) or TAU only (n = 50) and
assessed 16-weeks post-randomisation. Participants’ (ex) partners were offered support and 27 provided outcome
data. Thirty-one staff and 12 men who attended the intervention participated in focus groups or interviews that
were analysed using the framework approach. Pre-specified criteria assessed the feasibility of progression to a
definitive trial: 1) ≥ 60% of eligible male participants recruited; 2) intervention acceptable to staff and male
participants; 3) ≥ 70% of participants followed-up and 4) levels of substance use and 5) IPA perpetrated by men in
the intervention arm did not increase from average baseline level at 16-weeks post-randomisation.
Results: 70.7% (104/147) of eligible men were recruited. The formative evaluation confirmed the intervention’s
acceptability. Therapeutic alliance and session satisfaction were rated highly. The overall median rate of intervention
session attendance (of 14 compulsory sessions) was 28.6% (range 14.3–64.3% by the third cycle). 49.0% (51/104) of
men and 63.0% (17/27) of their (ex) partners were followed-up 16-weeks post-randomisation. This increased to
100% of men and women by cycle three. At follow-up, neither substance use nor IPA perpetration had worsened
for men in the intervention arm.
Conclusions: It was feasible to deliver the ADVANCE intervention in substance use treatment services, although it
proved difficult to collect data from female (ex)partners. While some progression criteria were met, others were not,
although improvements were demonstrated by the third cycle. Lessons learned will be implemented into the study
design for a definitive trial of the ADVANCE intervention
Right ventricle free wall mechanics in metabolic syndrome without type-2 diabetes: effects of a 3-month lifestyle intervention program
- …