163 research outputs found
Coherent transport in a two-electron quantum dot molecule
We investigate the dynamics of two interacting electrons confined to a pair
of coupled quantum dots driven by an external AC field. By numerically
integrating the two-electron Schroedinger equation in time, we find that for
certain values of the strength and frequency of the AC field we can cause the
electrons to be localised within the same dot, in spite of the Coulomb
repulsion between them. Reducing the system to an effective two-site model of
Hubbard type and applying Floquet theory leads to a detailed understanding of
this effect. This demonstrates the possibility of using appropriate AC fields
to manipulate entangled states in mesoscopic devices on extremely short
timescales, which is an essential component of practical schemes for quantum
information processing.Comment: 4 pages, 3 figures; the section dealing with the perturbative
treatment of the Floquet states has been substantially expanded to make it
easier to follo
The transition from the adiabatic to the sudden limit in core level photoemission: A model study of a localized system
We consider core electron photoemission in a localized system, where there is
a charge transfer excitation. The system is modelled by three electron levels,
one core level and two outer levels. The model has a Coulomb interaction
between these levels and the continuum states into which the core electron is
emitted. The model is simple enough to allow an exact numerical solution, and
with a separable potential an analytic solution. We calculate the ratio
r(omega) between the weights of the satellite and the main peak as a function
of the photon energy omega. The transition from the adiabatic to the sudden
limit takes place for quite small photoelectron kinetic energies. For such
small energies, the variation of the dipole matrix element is substantial and
described by the energy scale Ed. Without the coupling to the photoelectron,
the corresponding ratio r0(omega) is determined by Ed and the satellite
excitation energy dE. When the interaction potential with the continuum states
is introduced, a new energy scale Es=1/(2Rs^2) enters, where Rs is a length
scale of the interaction potential. At threshold there is typically a (weak)
constructive interference between intrinsic and extrinsic contributions, and
the ratio r(omega)/r0(omega) is larger than its limiting value for large omega.
The interference becomes small or weakly destructive for photoelectron energies
of the order Es. For larger energies r(omega)/r0(omega) therefore typically has
a weak undershoot. If this undershoot is neglected, r(omega)/r0(omega) reaches
its limiting value on the energy scale Es.Comment: 18 pages, latex2e, 13 eps figure
Investigation of oil palm harvesting tools design and technique on work-related musculoskeletal disorders of the upper body
The oil palm industry is one of the important sectors in Malaysia. The growth and development of this industry
shows that Malaysia is the world second-largest oil palm producers. However, in the fresh fruit bunch (FFB)
harvesting process, the harvesters are exposed to many types of work-related musculoskeletal disorders
(WMSDs). The FFB harvesters tend to develop WMSDs especially the shoulders and trunk. Hence, it is important
to identify the exposure levels, awkward postures and the reaction forces of muscle activity based on the posture
and movement of the harvesters when using pole, chisel and loading spike during the harvesting process. The
objective of this study was to investigate the effect of the design of oil palm FFB harvesting tools on WMSDs of
the upper body. Rapid Upper Limb Analysis (RULA) was used to investigate and assess the exposure level on the
harvester body during the harvesting process. The assessment showed that the shoulders and trunk have high
exposure level and undergo awkward posture. Human Musculoskeletal Model Analysis (HMMA) was used to
identify the reaction force exerted on the muscle during the FFB harvesting process. In this study, 4 muscles were
analysed including Triceps, Biceps, Erector Spinae and Psoas Major. The highest reaction force of 16.36 N was
found on the left triceps when handling a loading spike. In conclusion, it is important to address the risks by
reviewing all possible aspects that contribute to the WMSDs and interventions on the tool design, task and
working shifts may be required
Exploring morphological correlations among H2CO, 12CO, MSX and continuum mappings
There are relatively few H2CO mappings of large-area giant molecular cloud
(GMCs). H2CO absorption lines are good tracers for low-temperature molecular
clouds towards star formation regions. Thus, the aim of the study was to
identify H2CO distributions in ambient molecular clouds. We investigated
morphologic relations among 6-cm continuum brightness temperature (CBT) data
and H2CO (111-110; Nanshan 25-m radio telescope), 12CO (1--0; 1.2-m CfA
telescope) and midcourse space experiment (MSX) data, and considered the impact
of background components on foreground clouds. We report simultaneous 6-cm H2CO
absorption lines and H110\alpha radio recombination line observations and give
several large-area mappings at 4.8 GHz toward W49 (50'\times50'), W3
(70'\times90'), DR21/W75 (60'\times90') and NGC2024/NGC2023 (50'\times100')
GMCs. By superimposing H2CO and 12CO contours onto the MSX color map, we can
compare correlations. The resolution for H2CO, 12CO and MSX data was about 10',
8' and 18.3", respectively. Comparison of H2CO and 12CO contours, 8.28-\mu m
MSX colorscale and CBT data revealed great morphological correlation in the
large area, although there are some discrepancies between 12CO and H2CO peaks
in small areas. The NGC2024/NGC2023 GMC is a large area of HII regions with a
high CBT, but a H2CO cloud to the north is possible against the cosmic
microwave background. A statistical diagram shows that 85.21% of H2CO
absorption lines are distributed in the intensity range from -1.0 to 0 Jy and
the \Delta V range from 1.206 to 5 km/s.Comment: 18 pages, 22 figures, 5 tables. Accepted to be published in
Astrophysics and Space Scienc
Predictors of placebo response to local (intra-articular) therapy in osteoarthritis: An individual patient data meta-analysis protocol
© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. Introduction Osteoarthritis (OA) is a highly prevalent and disabling condition with limited safe and effective treatment options. Intra-articular therapies are increasingly being used, however whether the effect of these agents is due to active treatment or placebo remains unclear. As the placebo response can be attributed to multiple factors, assessment of the placebo response using individual patient data (IPD) meta-analysis will give insight into the different modifiers of response to placebo. The aim of this IPD meta-analysis is to investigate the predictors of placebo response in intra-articular injection trials in OA. IPD meta-analysis is considered to be superior to conventional meta-analysis, as it combines multiple trial data, facilitates the standardisation of analyses across different studies and allows measuring derivation of the desired information. Method and analysis A systematic literature search will be conducted for randomised clinical trials comparing corticosteroid and viscosupplementation/hyaluronic acid intra-articular injections with placebo for knee and hip OA. Pubmed (Medline), EMBASE, Web of Science, Cochrane Central and SCOPUS will be searched from inception to September 2018. Corresponding authors of the original trials will be contacted to obtain IPD. Risk of bias will be assessed using the Cochrane Collaboration's tool. The primary outcome will be change in pain from baseline. Secondary outcomes will be change in function and patient's global assessment. Potential predictors of placebo response assessed will include patient's characteristics, pain mechanism characteristics, radiographic severity, pain severity, intervention characteristics and trial design characteristics. A multilevel logistic regression analyses will be applied. Results will be reported using the Preferred Reporting Items for Systematic review and Meta-Analysis -IPD guidelines. Ethics and dissemination This study does not include identifiable data and ethical approval was obtained by the original investigators. Results of the IPD meta-analysis will be disseminated for publication in peer-reviewed journals and conference presentations. PROSPERO registration number CRD4201809518
(Sub)mm Interferometry Applications in Star Formation Research
This contribution gives an overview about various applications of (sub)mm
interferometry in star formation research. The topics covered are molecular
outflows, accretion disks, fragmentation and chemical properties of low- and
high-mass star-forming regions. A short outlook on the capabilities of ALMA is
given as well.Comment: 20 pages, 7 figures, in proceedings to "2nd European School on Jets
from Young Star: High Angular Resolution Observations". A high-resolution
version of the paper can be found at
http://www.mpia.de/homes/beuther/papers.htm
A Monte Carlo simulation approach to optimizing capacity in a high-volume congenital heart pediatric surgical center
Importance: Elective surgeries are primarily scheduled according to surgeon availability with less consideration of patients' postoperative cardiac intensive care unit (CICU) length of stay. Furthermore, the CICU census can exhibit a high rate of variation in which the CICU is operating at over-capacity, resulting in admission delays and cancellations; or under-capacity, resulting in underutilized labor and overhead expenditures.
Objective: To identify strategies to reduce variation in CICU occupancy levels and avoid late patient surgery cancellation.
Design: Monte Carlo simulation study of the daily and weekly CICU census at Boston Children's Hospital Heart Center. Data on all surgical admissions to and discharges from the CICU at Boston Children's Hospital between September 1, 2009 and November 2019 were included to obtain the distribution of length of stay for the simulation study. The available data allows us to model realistic length of stay samples that include short and extended lengths of stay.
Main Outcomes: Annual number of patient surgical cancellations and change in average daily census.
Results: We demonstrate that the models of strategic scheduling would result in up to 57% reduction in patient surgical cancellations, increase the historically low Monday census and decrease the historically higher late-mid-week (Wednesday and Thursday) censuses in our center.
Conclusions and Relevance: Use of strategic scheduling may improve surgical capacity and reduce the number of annual cancellations. The reduction of peaks and valleys in the weekly census corresponds to a reduction of underutilization and overutilization of the system
Associations of common breast cancer susceptibility alleles with risk of breast cancer subtypes in BRCA1 and BRCA2 mutation carriers
Introduction: More than 70 common alleles are known to be involved in breast cancer (BC) susceptibility, and several exhibit significant heterogeneity in their associations with different BC subtypes. Although there are differences in the association patterns between BRCA1 and BRCA2 mutation carriers and the general population for several loci, no study has comprehensively evaluated the associations of all known BC susceptibility alleles with risk of BC subtypes in BRCA1 and BRCA2 carriers. Methods: We used data from 15,252 BRCA1 and 8,211 BRCA2 carriers to analyze the associations between approximately 200,000 genetic variants on the iCOGS array and risk of BC subtypes defined by estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and triple-negative- (TN) status; morphologic subtypes; histological grade; and nodal involvement. Results: The estimated BC hazard ratios (HRs) for the 74 known BC alleles in BRCA1 carriers exhibited moderate correlations with the corresponding odds ratios from the general population. However, their associations with ER-positive BC in BRCA1 carriers were more consistent with the ER-positive as
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