2,502 research outputs found
Theory of Feshbach molecule formation in a dilute gas during a magnetic field ramp
Starting with coupled atom-molecule Boltzmann equations, we develop a
simplified model to understand molecule formation observed in recent
experiments. Our theory predicts several key features: (1) the effective
adiabatic rate constant is proportional to density; (2) in an adiabatic ramp,
the dependence of molecular fraction on magnetic field resembles an error
function whose width and centroid are related to the temperature; (3) the
molecular production efficiency is a universal function of the initial phase
space density, the specific form of which we derive for a classical gas. Our
predictions show qualitative agreement with the data from [Hodby et al, Phys.
Rev. Lett. {\bf{94}}, 120402 (2005)] without the use of adjustable parameters
Ant genomics (Hymenoptera: Formicidae): challenges to overcome and opportunities to seize
SN is funded by the Danish National
Research Foundation (DNRF57). YW is funded by BBSRC
grant BB/K004204/1, NERC grant NE/L00626X/1, and is
a fellow of the Software Sustainability Institute
SafeOrganic - Restrictive use of antibiotics in organic animal farming – a potential for safer, high quality products with less antibiotic resistant bacteria
Main research questions:
Antimicrobial resistance (AR) in the food-chain is a concern due to risk of treatment failure of humans.
- Do restrictions on antimicrobial (AB) usage in organic pig production lead to lower AR levels in organic pigs compared to conventional ones?
- Is lower AR a quality trait of organic pork?
- Does slaughtering of organic and conventional pigs together abolish this potential quality trait?
- Can markers for imprudent AR use in organic pig herds be identified
Angular momentum exchange between coherent light and matter fields
Full, three dimensional, time-dependent simulations are presented
demonstrating the quantized transfer of angular momentum to a Bose-Einstein
condensate from a laser carrying orbital angular momentum in a
Laguerre-Gaussian mode. The process is described in terms of coherent Bragg
scattering of atoms from a chiral optical lattice. The transfer efficiency and
the angular momentum content of the output coupled vortex state are analyzed
and compared with a recent experiment.Comment: 4 pages, 4 figure
Mesoscopic conductance fluctuations in InAs nanowire-based SNS junctions
We report a systematic experimental study of mesoscopic conductance
fluctuations in superconductor/normal/superconductor (SNS) devices
Nb/InAs-nanowire/Nb. These fluctuations far exceed their value in the normal
state and strongly depend on temperature even in the low-temperature regime.
This dependence is attributed to high sensitivity of perfectly conducting
channels to dephasing and the SNS fluctuations thus provide a sensitive probe
of dephasing in a regime where normal transport fails to detect it. Further,
the conductance fluctuations are strongly non-linear in bias voltage and reveal
sub-gap structure. The experimental findings are qualitatively explained in
terms of multiple Andreev reflections in chaotic quantum dots with imperfect
contacts.Comment: Manuscript and supplemen
Superconductivity enhanced conductance fluctuations in few layer graphene nanoribbons
We investigate the mesoscopic disorder induced rms conductance variance
in a few layer graphene nanoribbon (FGNR) contacted by two
superconducting (S) Ti/Al contacts. By sweeping the back-gate voltage, we
observe pronounced conductance fluctuations superimposed on a linear background
of the two terminal conductance G. The linear gate-voltage induced response can
be modeled by a set of inter-layer and intra-layer capacitances.
depends on temperature T and source-drain voltage .
increases with decreasing T and . When lowering , a
pronounced cross-over at a voltage corresponding to the superconducting energy
gap is observed. For |V_{sd}|\ltequiv \Delta the fluctuations are
markedly enhanced. Expressed in the conductance variance of one
graphene-superconducutor (G-S) interface, values of 0.58 e^2/h are obtained at
the base temperature of 230 mK. The conductance variance in the sub-gap region
are larger by up to a factor of 1.4-1.8 compared to the normal state. The
observed strong enhancement is due to phase coherent charge transfer caused by
Andreev reflection at the nanoribbon-superconductor interface.Comment: 15 pages, 5 figure
Long-term methimazole therapy in Graves' hyperthyroidism and adverse reactions: a Danish multicenter study
PURPOSE: In this prospective multicenter study with patients newly diagnosed with Graves’ hyperthyroidism (GH), we studied the timing and characteristics of adverse drug reactions in patients treated with anti-thyroid drugs (ATD) for up to 48 months. METHODS: Patients with GH were treated with ATD until remission and hereafter with a low-dose regime to keep the patients in remission. The patients were followed with blood samples and recording of adverse events approximately every second month for the first 2 years and every third month for the following 2 years. RESULTS: We included 208 patients and the patients were treated for a median of 22 (range: 0.5–49) months. Ten percent of the patients experienced adverse drug reactions and 75% of the cases occurred during the first 6 months. After 24 months, the methimazole dose was lowered to 5 mg/day, and after this time point, no further adverse drug reactions were recorded. Skin reactions were the most prominent reaction, comprising 68% of the registered reactions, and no hepatic and bonemarrow affection was recorded. CONCLUSION: With this study, we report the frequency, timing of occurrence, and characteristics of adverse drug reactions when treating GH with the ATD drug methimazole for up to 48 months. Long-term low-dose methimazole treatment can be a cost-effective and straightforward treatment option if adverse drug reactions such as severe hepatic and bone marrow affection are kept in mind
Clinical outcomes and safety assessment in elderly patients undergoing decompressive laminectomy for lumbar spinal stenosis: a prospective study
<p>Abstract</p> <p>Background</p> <p>To assess safety, risk factors and clinical outcomes in elderly patients with spinal stenosis after decompressive laminectomy.</p> <p>Methods</p> <p>A prospective cohort of patients 70 years and older with spinal stenosis undergoing conventional laminectomy without fusion (n = 101) were consecutively enrolled from regular clinical practice and reassessed at 3 and 12 months. Primary outcome was change in health related quality of life measured (HRQL) with EuroQol-5 D (EQ-5D). Secondary outcomes were safety assessment, changes in Oswestry disability index (ODI), Visual Analogue Scale (EQ-VAS) score for self reported health, VAS score for leg and back pain and patient satisfaction. We used regression analyses to evaluate risk factors for less improvement.</p> <p>Results</p> <p>The mean EQ-5 D total score were 0.32, 0.63 and 0.60 at baseline, 3 months and 12 months respectively, and represents a statistically significant (P < 0.001) improvement. Effect size was > 0.8. Mean ODI score at baseline was 44.2, at 3 months 25.6 and at 27.9. This represents an improvement for all post-operative scores. A total of 18 (18.0%) complications were registered with 6 (6.0%) classified as major, including one perioperative death. Patients stating that the surgery had been beneficial at 3 months was 82 (89.1%) and at 12 months 73 (86.9%). The only predictor found was patients with longer duration of leg pain had less improvement in ODI (P < 0.001). Increased age or having complications did not predict a worse outcome in any of the outcome variables.</p> <p>Conclusions</p> <p>Properly selected patients of 70 years and older can expect a clinical meaningful improvement of HRQL, functional status and pain after open laminectomy without fusion. The treatment seems to be safe. However, patients with longstanding leg-pain prior to operation are less likely to improve one year after surgery.</p
Effective Swarm Parameters And Transport Coefficients In CO2 Laser Mixtures
A pulsed electron swarm technique has been used to obtain effective attachment and ionization cross-sections as well as electron drift velocities in mixtures of CO2 laser interest. In binary CO2:N 2 mixtures, below a reduced electric field of E/N=60*10 -17 V cm2, attachment was the principal ion production process. (N is the total gas number density.) The reduced attachment coefficients measured were small and in excellent agreement with numerical predictions. In ternary mixtures of He:CO2:N2, positive ion formation described by Townsend\u27s first ionisation coefficient played a more important role over the same range of E/N. The reduced coefficient for total ion formation was measured and found to be in good agreement with numerical calculations. Electron drift velocities in both the binary and ternary mixtures were determined using a time-of-flight technique. Overall agreement with previous experimental and numerical results was good
Static Properties of Trapped Bose-Fermi Mixed Condensate of Alkali Atoms
Static properties of a bose-fermi mixture of trapped potassium atoms are
studied in terms of coupled Gross-Pitaevskii and Thomas-Fermi equations for
both repulsive and attractive bose-fermi interatomic potentials. Qualitative
estimates are given for solutions of the coupled equations, and the parameter
regions are obtained analytically for the boson-density profile change and for
the boson/fermion phase separation. Especially, the parameter ratio
is found that discriminates the region of the large boson-profile change. These
estimates are applied for numerical results for the potassium atoms and checked
their consistency. It is suggested that a small fraction of fermions could be
trapped without an external potential for the system with an attractive
boson-fermion interaction.Comment: 8 pages,5 figure
- …