3,805 research outputs found
Reconfigurable self-sufficient traps for ultracold atoms based on a superconducting square
We report on the trapping of ultracold atoms in the magnetic field formed
entirely by persistent supercurrents induced in a thin film type-II
superconducting square. The supercurrents are carried by vortices induced in
the 2D structure by applying two magnetic field pulses of varying amplitude
perpendicular to its surface. This results in a self-sufficient quadrupole trap
that does not require any externally applied fields. We investigate the
trapping parameters for different supercurrent distributions. Furthermore, to
demonstrate possible applications of these types of supercurrent traps we show
how a central quadrupole trap can be split into four traps by the use of a bias
field.Comment: 5 pages, 7 figure
Programmable trap geometries with superconducting atom chips
We employ the hysteretic behavior of a superconducting thin film in the
remanent state to generate different traps and flexible magnetic potentials for
ultra-cold atoms. The trap geometry can be programmed by externally applied
fields. This new approach for atom-optics is demonstrated by three different
trap types realized on a single micro-structure: a Z-type trap, a double trap
and a bias field free trap. Our studies show that superconductors in the
remanent state provide a new versatile platform for atom-optics and
applications in ultra-cold quantum gases
Enabling multiplexed testing of pooled donor cells through whole-genome sequencing
We describe a method that enables the multiplex screening of a pool of many different donor cell lines. Our method accurately predicts each donor proportion from the pool without requiring the use of unique DNA barcodes as markers of donor identity. Instead, we take advantage of common single nucleotide polymorphisms, whole-genome sequencing, and an algorithm to calculate the proportions from the sequencing data. By testing using simulated and real data, we showed that our method robustly predicts the individual proportions from a mixed-pool of numerous donors, thus enabling the multiplexed testing of diverse donor cells en masse.National Human Genome Research Institute (U.S.) (Grant RM1HG008525)Robert Wood Johnson Foundation (Grant 74178
Magnetic confinement of neutral atoms based on patterned vortex distributions in superconducting disks and rings
We propose and analyze neutral atom traps generated by vortices imprinted by
magnetic field pulse sequences in type-II superconducting disks and rings. We
compute the supercurrent distribution and magnetic field resulting from the
vortices in the superconductor. Different patterns of vortices can be written
by versatile loading field sequences. We discuss in detail procedures to
generate quadrupole traps, self-sufficient traps and ring traps based on
superconducting disks and rings. The ease of creating these traps and the low
current noise in supercurrent carrying structures makes our approach attractive
for designing atom chip interferometers and probes.Comment: 7 pages, 9 figure
Trapping of ultra-cold atoms with the magnetic field of vortices in a thin film superconducting micro-structure
We store and control ultra-cold atoms in a new type of trap using magnetic
fields of vortices in a high temperature superconducting micro-structure. This
is the first time ultra-cold atoms have been trapped in the field of magnetic
flux quanta. We generate the attractive trapping potential for the atoms by
combining the magnetic field of a superconductor in the remanent state with
external homogeneous magnetic fields. We show the control of crucial atom trap
characteristics such as an efficient intrinsic loading mechanism, spatial
positioning of the trapped atoms and the vortex density in the superconductor.
The measured trap characteristics are in good agreement with our numerical
simulations.Comment: 4pages, comments are welcom
Distribution of COL9A2 and COL9A3 Gene Polymorphism in Male Chinese Singaporean - A Pilot Observational Study
The association between allelic variants and lumbar disc degenerative disease (DDD) has been investigated in Europe and Northern Asia. However, this has not been investigated in Southeast Asia. This observational study aims to compare the distribution of COL9A2 and COL9A3 gene polymorphism among male Chinese Singaporeans with and without lumbar DDD. COL9A2 gene polymorphism was investigated in p326 (tryptophan 2, Trp2 and glutamine 2, Gln2, alleles) and p335 (valine 2 or Val2 allele). COL9A3 gene polymorphism was investigated in p17 (glycine 3 or Gly3 allele) and p103 (tryptophan 3 or Trp3 allele). The Val2 allele was significantly decreased in the group with lumbar DDD (p < 0.05). No significant difference in allelic distributions of Trp2, Gln2 and Gly3 was found. The Trp3 allele was absent from all the subjects. The presence of at least one Val2 allele appears to have a protective effect against DDD. However, these should be interpreted with caution, given the limitations. Further investigations are warranted in order to verify such genetic predisposition prior to the potential development of preventative or therapeutic strategies in the near future
An Assessment of Risk of Iodine Deficiency Among Pregnant Women in Sarawak, Malaysia
Previous findings from a state-wide Iodine Deficiency Disorders (IDD) study among pregnant women (PW) in Sarawak indicated that PW are at risk of IDD and further assessment is needed. This paper describes the methodology used in conducting this study for an assessment of risk of iodine deficiency among pregnant women in Sarawak, Malaysia. A total of 30 maternal child health care clinics (MCHCs) were selected using probability proportional to population size (PPS) sampling technique. The PW sample size was calculated based on 95% confidence interval (CI), relative precision of 5%, design effect of 2, anticipated IDD prevalence of 65.0% and non-response rate of 20%. Thus, the total sample size required was 750 (25 respondents per selected MCHC). The WHO Expanded Programme on Immunization (EPI) surveys approach was used to randomly select the first respondent and subsequent respondents were chosen until the required number of PW was met. The required data were obtained through: face-to-face interviews (socio-demographic and food frequency questionnaire), clinical assessments (thyroid size, and hyper/hypothyroidism) and biochemical analysis (urine and blood serum). A total of 677 PW responded in the study with a response rate of 90.2%. Majority of the PW were at second gravida, aged 25-29 years old and of Malay ethnicity. The methodology used in this study was based on International guidelines which may provide state's estimates. All the necessary steps were taken into consideration to ensure valid and reliable findings on current iodine status among PW
High-Resolution Subtropical Summer Precipitation Derived from Dynamical Downscaling of the NCEP-DOE Reanalysis: How Much Small-Scale Information Is Added by a Regional Model?
This study assesses the regional-scale summer precipitation produced by the dynamical downscaling of
analyzed large-scale fields. The main goal of this study is to investigate how much the regional model adds smaller scale
precipitation information that the large-scale fields do not resolve. The modeling region for this study covers the
southeastern United States (Florida, Georgia, Alabama, South Carolina, and North Carolina) where the summer climate
is subtropical in nature, with a heavy influence of regional-scale convection. The coarse resolution (2.5deg latitude/longitude)
large-scale atmospheric variables from the National Center for Environmental Prediction (NCEP)/DOE reanalysis (R2) are
downscaled using the NCEP Environmental Climate Prediction Center regional spectral model (RSM) to produce
precipitation at 20 km resolution for 16 summer seasons (19902005). The RSM produces realistic details in the regional
summer precipitation at 20 km resolution. Compared to R2, the RSM-produced monthly precipitation shows better
agreement with observations. There is a reduced wet bias and a more realistic spatial pattern of the precipitation
climatology compared with the interpolated R2 values. The root mean square errors of the monthly R2 precipitation are
reduced over 93 (1,697) of all the grid points in the five states (1,821). The temporal correlation also improves over 92
(1,675) of all grid points such that the domain-averaged correlation increases from 0.38 (R2) to 0.55 (RSM). The RSM
accurately reproduces the first two observed eigenmodes, compared with the R2 product for which the second mode is
not properly reproduced. The spatial patterns for wet versus dry summer years are also successfully simulated in RSM.
For shorter time scales, the RSM resolves heavy rainfall events and their frequency better than R2. Correlation and
categorical classification (above/near/below average) for the monthly frequency of heavy precipitation days is also
significantly improved by the RSM
A review of segmentation and deformable registration methods applied to adaptive cervical cancer radiation therapy treatment planning
Objective: Manual contouring and registration for radiotherapy treatment planning and online adaptation for cervical cancer radiation therapy in computed tomography (CT) and magnetic resonance images (MRI) are often necessary. However manual intervention is time consuming and may suffer from inter or intra-rater variability. In recent years a number of computer-guided automatic or semi-automatic segmentation and registration methods have been proposed. Segmentation and registration in CT and MRI for this purpose is a challenging task due to soft tissue deformation, inter-patient shape and appearance variation and anatomical changes over the course of treatment. The objective of this work is to provide a state-of-the-art review of computer-aided methods developed for adaptive treatment planning and radiation therapy planning for cervical cancer radiation therapy. Methods: Segmentation and registration methods published with the goal of cervical cancer treatment planning and adaptation have been identified from the literature (PubMed and Google Scholar). A comprehensive description of each method is provided. Similarities and differences of these methods are highlighted and the strengths and weaknesses of these methods are discussed. A discussion about choice of an appropriate method for a given modality is provided. Results: In the reviewed papers a Dice similarity coefficient of around 0.85 along with mean absolute surface distance of 2-4. mm for the clinically treated volume were reported for transfer of contours from planning day to the treatment day. Conclusions: Most segmentation and non-rigid registration methods have been primarily designed for adaptive re-planning for the transfer of contours from planning day to the treatment day. The use of shape priors significantly improved segmentation and registration accuracy compared to other models
Universal conductance enhancement and reduction of the two-orbital Kondo effect
We investigate theoretically the linear and nonlinear conductance through a
nanostructure with two-fold degenerate single levels, corresponding to the
transport through nanostructures such as a carbon nanotube, or double dot
systems with capacitive interaction. It is shown that the presence of the
interaction asymmetry between orbits/dots affects significantly the profile of
the linear conductance at finite temperature, and, of the nonlinear
conductance, particularly around half-filling, where the two-particle Kondo
effect occurs. Within the range of experimentally feasible parameters, the
SU(4) universal behavior is suggested, and comparison with relevant experiments
is made.Comment: 10 pages, 16 figure
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