2,652 research outputs found
Direct imaging of a digital-micromirror device for configurable microscopic optical potentials
Programable spatial light modulators (SLMs) have significantly advanced the
configurable optical trapping of particles. Typically, these devices are
utilized in the Fourier plane of an optical system, but direct imaging of an
amplitude pattern can potentially result in increased simplicity and
computational speed. Here we demonstrate high-resolution direct imaging of a
digital micromirror device (DMD) at high numerical apertures (NA), which we
apply to the optical trapping of a Bose-Einstein condensate (BEC). We utilise a
(1200 x 1920) pixel DMD and commercially available 0.45 NA microscope
objectives, finding that atoms confined in a hybrid optical/magnetic or
all-optical potential can be patterned using repulsive blue-detuned (532 nm)
light with 630(10) nm full-width at half-maximum (FWHM) resolution, within 5%
of the diffraction limit. The result is near arbitrary control of the density
the BEC without the need for expensive custom optics. We also introduce the
technique of time-averaged DMD potentials, demonstrating the ability to produce
multiple grayscale levels with minimal heating of the atomic cloud, by
utilising the high switching speed (20 kHz maximum) of the DMD. These
techniques will enable the realization and control of diverse optical
potentials for superfluid dynamics and atomtronics applications with quantum
gases. The performance of this system in a direct imaging configuration has
wider application for optical trapping at non-trivial NAs.Comment: 9 page
Calibration of a single atom detector for atomic micro chips
We experimentally investigate a scheme for detecting single atoms
magnetically trapped on an atom chip. The detector is based on the
photoionization of atoms and the subsequent detection of the generated ions. We
describe the characterization of the ion detector with emphasis on its
calibration via the correlation of ions with simultaneously generated
electrons. A detection efficiency of 47.8% (+-2.6%) is measured, which is
useful for single atom detection, and close to the limit allowing atom counting
with sub-Poissonian uncertainty
Phase II trial of the oral platinum complex JM216 in non-small-cell lung cancer: An EORTC early clinical studies group investigation
Background JM216 is a new oral platinum complex with dose-limiting toxicity myelosuppresssion, now undergoing phase II evaluation. Patients and methods JM216 was evaluated as first line therapy in non-small-cell lung cancer. Seventeen patients received 120 mg/m2/day for five days repeated every three weeks. Results Toxicity was manageable, the commonest side-effects being nausea, vomiting, diarrhoea, constipation and asthenia. Myelososuppression was generally grade <2 and there were no cases of neutropenic sepsis or bleeding. Thirteen patients were fully evaluable for response. No sustained objective responses were reported. One patient was reported as stable disease had a partial response after three courses but was progressing again after four. An additional five patients had stable disease (46.2%). Conclusions Although some patients may have had useful palliation, JM216 did not appear to have significant antitumour activity in non-small-cell lung cance
Cluster observations of surface waves on the dawn flank magnetopause
On 14 June 2001 the four Cluster spacecraft recorded multiple encounters of the dawn-side flank magnetopause. The characteristics of the observed electron populations varied between a cold, dense magnetosheath population and warmer, more rarified boundary layer population on a quasi-periodic basis. The demarcation between these two populations can be readily identified by gradients in the scalar temperature of the electrons. An analysis of the differences in the observed timings of the boundary at each spacecraft indicates that these magnetopause crossings are consistent with a surface wave moving across the flank magnetopause. When compared to the orientation of the magnetopause expected from models, we find that the leading edges of these waves are approximately 45° steeper than the trailing edges, consistent with the Kelvin-Helmholtz (KH) driving mechanism. A stability analysis of this interval suggests that the magnetopause is marginally stable to this mechanism during this event. Periods in which the analysis predicts that the magnetopause is unstable correspond to observations of greater wave steepening. Analysis of the pulses suggests that the waves have an average wavelength of approximately 3.4 <i>R<sub>E</sub></i> and move at an average speed of ~65km s<sup>-1</sup> in an anti-sunward and northward direction, despite the spacecraft location somewhat south of the GSE <i>Z=0</i> plane. This wave propagation direction lies close to perpendicular to the average magnetic field direction in the external magnetosheath, suggesting that these waves may preferentially propagate in the direction that requires no bending of these external field lines<br><br> <b>Key words.</b> Magnetospheric physics (magnetospheric configuration and dynamics; MHD waves and unstabilities; solar wind-magnetosphere interactions
Optical microrheology using rotating laser-trapped particles
We demonstrate an optical system that can apply and accurately measure the
torque exerted by the trapping beam on a rotating birefringent probe particle.
This allows the viscosity and surface effects within liquid media to be
measured quantitatively on a micron-size scale using a trapped rotating
spherical probe particle. We use the system to measure the viscosity inside a
prototype cellular structure.Comment: 5 pages, 4 figures. v2: bibliographic details, minor text correction
The 1<z<5 Infrared Luminosity Function of Type I Quasars
We determine the rest-frame 8 micron luminosity function of type I quasars
over the redshift range 1<z<5. Our sample consists of 292 24 micron sources
brighter than 1 mJy selected from 7.17 square degrees of the Spitzer Space
Telescope MIPS survey of the NOAO Deep Wide-Field Survey Bootes field. The AGN
and Galaxy Evolution Survey (AGES) has measured redshifts for 270 of the R<21.7
sources and we estimate that the contamination of the remaining 22 sources by
stars and galaxies is low. We are able to select quasars missed by ultra-violet
excess quasar surveys, including reddened type I quasars and 2.2<z<3.0 quasars
with optical colors similar to main sequence stars. We find reddened type I
quasars comprise 20% of the type I quasar population. Nonetheless, the shape,
normalization, and evolution of the rest-frame 8 micron luminosity function is
comparable to that of quasars selected from optical surveys. The 8 micron
luminosity function of type I quasars is well approximated by a power-law with
index -2.75(+/-0.14). We directly measure the peak of the quasar space density
to be at z=2.6(+/-0.3).Comment: Accepted for publication in the ApJ, 19 pages, 12 figure
AzTEC 1.1 mm observations of high-z protocluster environments : SMG overdensities and misalignment between AGN jets and SMG distribution
We present observations at 1.1 mm towards 16 powerful radio galaxies and a radio-quiet quasar at 0.5 > z > 6.3 acquired with the AzTEC camera mounted at the James Clerk Maxwell Telescope and Atacama Submillimeter Telescope Experiment to study the spatial distribution of submillimetre galaxies (SMGs) towards possible protocluster regions. The survey covers a total area of 1.01 sq deg with rms depths of 0.52-1.44 mJy and detects 728 sources above 3σ. We find overdensities of a factor of ~2 in the source counts of three individual fields (4C+23.56, PKS1138-262, and MRC0355-037) over areas of ~200 sq deg. When combining all fields, the source-count analysis finds an overdensity that reaches a factor ≳ 3 at S 1.1mm = 4mJy covering a 1.5-arcmin-radius area centred on the active galactic nucleus. The large size of our maps allows us to establish that beyond a radius of 1.5 arcmin, the radial surface density of SMGs falls to that of a blank field. In addition, we find a trend for SMGs to align closely to a perpendicular direction with respect to the radio jets of the powerful central radio galaxies (73 -14 +13 deg). This misalignment is found over projected comoving scales of 4-20 Mpc, departs from perfect alignment (0 deg) by ~5σ, and apparently has no dependence on SMG luminosity. Under the assumption that the AzTEC sources are at the redshift of the central radio galaxy, the misalignment reported here can be interpreted as SMGs preferentially inhabiting mass-dominant filaments funnelling material towards the protoclusters, which are also the parent structures of the radio galaxies.Peer reviewe
SXDF-UDS-CANDELS-ALMA 1.5 arcmin deep survey
We have conducted 1.1 mm ALMA observations of a contiguous or 1.5 arcmin window in the SXDF-UDS-CANDELS. We achieved a 5
sensitivity of 0.28 mJy, providing a flat sensus of dusty star-forming galaxies
with (for =40K) up to
thanks to the negative K-correction at this wavelength. We detected 5
brightest sources (S/N6) and 18 low-significance sources (5S/N4; these
may contain spurious detections, though). One of the 5 brightest ALMA sources
( mJy) is extremely faint in the WFC3 and
VLT/HAWK-I images, demonstrating that a contiguous ALMA imaging survey is able
to uncover a faint dust-obscured population that is invisible in deep
optical/near-infrared surveys. We found a possible [CII]-line emitter at
or a low- CO emitting galaxy within the field, which may allow us
to constrain the [CII] and/or the CO luminosity functions across the history of
the universe.Comment: 4 pages, 2 figures, 1 table, to appear in the proceedings of IAU
Symposium 319 "Galaxies at High Redshift and Their Evolution over Cosmic
Time", eds. S. Kaviraj & H. Ferguso
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