3,845 research outputs found
Tapered optical fibers as tools for probing magneto-optical trap characteristics
We present a novel technique for measuring the characteristics of a
magneto-optical trap for cold atoms by monitoring the spontaneous emission from
trapped atoms coupled into the guided mode of a tapered optical nanofiber. We
show that the nanofiber is highly sensitive to very small numbers of atoms
close to its surface. The size and shape of the MOT, determined by translating
the cold atom cloud across the tapered fiber, is in excellent agreement with
measurements obtained using the conventional method of fluorescence imaging
using a CCD camera. The coupling of atomic fluorescence into the tapered fiber
also allows us to monitor the loading and lifetime of the trap. The results are
compared to those achieved by focusing the MOT fluorescence onto a photodiode
and it was seen that the tapered fiber gives slightly longer loading and
lifetime measurements due to the sensitivity of the fiber, even when very few
atoms are present.Comment: 21 pages, 5 figure
An ultra-bright atom laser
We present a novel, ultra-bright atom-laser and ultra-cold thermal atom beam.
Using rf-radiation we strongly couple the magnetic hyperfine levels of 87Rb
atoms in a magnetically trapped Bose-Einstein condensate. At low rf-frequencies
gravity opens a small hole in the trapping potenital and a well collimated,
extremely bright atom laser emerges from just below the condensate. As opposed
to traditional atom lasers based on weak coupling, this technique allows us to
outcouple atoms at an arbitrarily large rate. We demonstrate an increase in
flux per atom in the BEC by a factor of sixteen compared to the brightest
quasi-continuous atom laser. Furthermore, we produce by two orders of magnitude
the coldest thermal atom beam to date (200 nK).Comment: 20 pages, 9 figures, supplementary material online at
http://www.bec.g
Six years survival on imatinib with no disease progression after diagnosis of metastatic duodenal gastrointestinal stromal tumour: a case report
Introduction: A duodenal Gastrointestinal Stromal Tumour (GIST) is a rare finding and until recently advanced disease had a poor prognosis. A PubMed search revealed no reports of more than five years survival of inoperable GIST on chemotherapy with WHO performance status zero.
Case Presentation: A 68 year old female was diagnosed with unresectable GIST in the duodenum with metastasis to liver, pancreas and omentum in November 2001. She was
commenced on imatinib mesylate (Glivec) chemotherapy. This case report was prepared from the medical records and radiology reports. She had good tolerance with stable disease. After six years her CT scan showed no disease progression and her WHO performance status was zero.
Conclusion: This report supports the view that imatinib is a safe and effective drug in controlling
disease progression in advanced metastatic GIST and plays an important role in improving the patient's quality of life
Dynamics and Instabilities of Planar Tensile Cracks in Heterogeneous Media
The dynamics of tensile crack fronts restricted to advance in a plane are
studied. In an ideal linear elastic medium, a propagating mode along the crack
front with a velocity slightly less than the Rayleigh wave velocity, is found
to exist. But the dependence of the effective fracture toughness on
the crack velocity is shown to destabilize the crack front if
. Short wavelength radiation due to weak random
heterogeneities leads to this instability at low velocities. The implications
of these results for the crack dynamics are discussed.Comment: 12 page
Evidence for a change in the nuclear mass surface with the discovery of the most neutron-rich nuclei with 17<Z <25
The results of measurements of the production of neutron-rich nuclei by the
fragmentation of a 76-Ge beam are presented. The cross sections were measured
for a large range of nuclei including fifteen new isotopes that are the most
neutron-rich nuclides of the elements chlorine to manganese (50-Cl, 53-Ar,
55,56-K, 57,58-Ca, 59,60,61-Sc, 62,63-Ti, 65,66-V, 68-Cr, 70-Mn). The enhanced
cross sections of several new nuclei relative to a simple thermal evaporation
framework, previously shown to describe similar production cross sections,
indicates that nuclei in the region around 62-Ti might be more stable than
predicted by current mass models and could be an indication of a new island of
inversion similar to that centered on 31-Na.Comment: 4 pages, 3 figures, to be published in Physical Review Letters, 200
Enhanced Production of Neutron-Rich Rare Isotopes in Peripheral Collisions at Fermi Energies
A large enhancement in the production of neutron-rich projectile residues is
observed in the reactions of a 25 MeV/nucleon 86Kr beam with the neutron rich
124Sn and 64Ni targets relative to the predictions of the EPAX parametrization
of high-energy fragmentation, as well as relative to the reaction with the less
neutron-rich 112Sn target. The data demonstrate the significant effect of the
target neutron-to-proton ratio (N/Z) in peripheral collisions at Fermi
energies. A hybrid model based on a deep-inelastic transfer code (DIT) followed
by a statistical de-excitation code appears to account for part of the observed
large cross sections. The DIT simulation indicates that the production of the
neutron-rich nuclides in these reactions is associated with peripheral nucleon
exchange. In such peripheral encounters, the neutron skins of the neutron-rich
124Sn and 64Ni target nuclei may play an important role. From a practical
viewpoint, such reactions between massive neutron-rich nuclei offer a novel and
attractive synthetic avenue to access extremely neutron-rich rare isotopes
towards the neutron-drip line.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
Single shot measurement of a silicon single electron transistor
We have fabricated a custom cryogenic Complementary Metal-Oxide-Semiconductor
(CMOS) integrated circuit that has a higher measurement bandwidth compared with
conventional room temperature electronics. This allowed implementing single
shot operations and observe the real-time evolution of the current of a
phosphorous-doped silicon single electron transistor that was irradiated with a
microwave pulse. Relaxation times up to 90 us are observed, suggesting the
presence of well isolated electron excitations within the device. It is
expected that these are associated with long decoherence time and the device
may be suitable for quantum information processing
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