2,122 research outputs found
Hepatic Cryotherapy and Subsequent Hepatic Arterial Chemotherapy for Colorectal Metastases to the Liver
This paper presents an experience of thirty consecutive
patients with hepatic colorectal metastases
who were treated with hepatic cryotherapy and
subsequent hepatic arterial infusion (HAI) chemotherapy
using 5FU
Discovery and Characterization of a Caustic Crossing Microlensing Event in the SMC
We present photometric observations and analysis of the second microlensing
event detected towards the Small Magellanic Cloud (SMC), MACHO Alert 98-SMC-1.
This event was detected early enough to allow intensive observation of the
lightcurve. These observations revealed 98-SMC-1 to be the first caustic
crossing, binary microlensing event towards the Magellanic Clouds to be
discovered in progress.
Frequent coverage of the evolving lightcurve allowed an accurate prediction
for the date of the source crossing out of the lens caustic structure. The
caustic crossing temporal width, along with the angular size of the source
star, measures the proper motion of the lens with respect to the source, and
thus allows an estimate of the location of the lens. Lenses located in the
Galactic halo would have a velocity projected to the SMC of v^hat ~1500 km/s,
while an SMC lens would typically have v^hat ~60 km/s.
We have performed a joint fit to the MACHO/GMAN data presented here,
including recent EROS data of this event. These joint data are sufficient to
constrain the time for the lens to move an angle equal to the source angular
radius; 0.116 +/- 0.010 days. We estimate a radius for the lensed source of 1.4
+/- 0.1 R_sun. This yields a projected velocity of v^hat = 84 +/- 9 km/s. Only
0.15% of halo lenses would be expected to have a v^hat value at least as small
as this, while 31% of SMC lenses would be expected to have v^hat as large as
this. This implies that the lensing system is more likely to reside in the SMC
than in the Galactic halo.Comment: 16 pages, including 3 tables and 3 figures; submitted to The
Astrophysical Journa
An absolute calibration system for millimeter-accuracy APOLLO measurements
Lunar laser ranging provides a number of leading experimental tests of
gravitation -- important in our quest to unify General Relativity and the
Standard Model of physics. The Apache Point Observatory Lunar Laser-ranging
Operation (APOLLO) has for years achieved median range precision at the ~2 mm
level. Yet residuals in model-measurement comparisons are an order-of-magnitude
larger, raising the question of whether the ranging data are not nearly as
accurate as they are precise, or if the models are incomplete or
ill-conditioned. This paper describes a new absolute calibration system (ACS)
intended both as a tool for exposing and eliminating sources of systematic
error, and also as a means to directly calibrate ranging data in-situ. The
system consists of a high-repetition-rate (80 MHz) laser emitting short (< 10
ps) pulses that are locked to a cesium clock. In essence, the ACS delivers
photons to the APOLLO detector at exquisitely well-defined time intervals as a
"truth" input against which APOLLO's timing performance may be judged and
corrected. Preliminary analysis indicates no inaccuracies in APOLLO data beyond
the ~3 mm level, suggesting that historical APOLLO data are of high quality and
motivating continued work on model capabilities. The ACS provides the means to
deliver APOLLO data both accurate and precise below the 2 mm level.Comment: 21 pages, 10 figures, submitted to Classical and Quantum Gravit
Damage identification in a concrete beam using curvature difference ratio
Previous studies utilising changes in mode shape or curvature to locate damage rely on the fact that the greatest change occurs around the defect. However, in concrete beams this fact is undermined due to the nature of the defect as distributed multi-site cracks. In addition, differences in mode shape and curvature as ways to locate the damage is unstable because of occurrence of modal nodes and inflection points. In this paper, one interesting solution to this problem is being tested by establishing a new non-dimensional expression designated the 'Curvature Difference Ratio (CDR)'. This parameter exploits the ratio of differences in curvature of a specific mode shape for a damaged stage and another reference stage. The expression CDR is reasonably used to locate the damage and estimate the dynamic bending stiffness in a successively loaded 6m concrete beam. Results obtained by the proposed technique are tested and validated with a case study results done by Ren and De Roeck [1] also by Maeck and De Roeck [2]. Another contribution of this work is that relating changes in vibration properties to the design bending moment at beam sections as defined in Eurocode 2 specifications [3]. Linking between a beam section condition and the change in vibration data will help to give a better comprehension on the beam condition than the applied load
Mesolensing Explorations of Nearby Masses: From Planets to Black Holes
Nearby masses can have a high probability of lensing stars in a distant
background field. High-probability lensing, or mesolensing, can therefore be
used to dramatically increase our knowledge of dark and dim objects in the
solar neighborhood, where it can discover and study members of the local dark
population (free-floating planets, low-mass dwarfs, white dwarfs, neutron
stars, and stellar mass black holes). We can measure the mass and transverse
velocity of those objects discovered (or already known), and determine whether
or not they are in binaries with dim companions. We explore these and other
applications of mesolensing, including the study of forms of matter that have
been hypothesized but not discovered, such as intermediate-mass black holes,
dark matter objects free-streaming through the Galactic disk, and planets in
the outermost regions of the solar system. In each case we discuss the
feasibility of deriving results based on present-day monitoring systems, and
also consider the vistas that will open with the advent of all-sky monitoring
in the era of the Panoramic Survey Telescope and Rapid Response System
(Pan-STARRS), and the Large Synoptic Survey Telescope (LSST).Comment: To appear in the Astrophysical Journal; 10 pages, no figure
Lightcurves of Type Ia Supernovae from Near the Time of Explosion
We present a set of 11 type Ia supernova (SN Ia) lightcurves with dense,
pre-maximum sampling. These supernovae (SNe), in galaxies behind the Large
Magellanic Cloud (LMC), were discovered by the SuperMACHO survey. The SNe span
a redshift range of z = 0.11 - 0.35. Our lightcurves contain some of the
earliest pre-maximum observations of SNe Ia to date. We also give a functional
model that describes the SN Ia lightcurve shape (in our VR-band). Our function
uses the "expanding fireball" model of Goldhaber et al. (1998) to describe the
rising lightcurve immediately after explosion but constrains it to smoothly
join the remainder of the lightcurve. We fit this model to a composite observed
VR-band lightcurve of three SNe between redshifts of 0.135 to 0.165. These SNe
have not been K-corrected or adjusted to account for reddening. In this
redshift range, the observed VR-band most closely matches the rest frame
V-band. Using the best fit to our functional description of the lightcurve, we
find the time between explosion and observed VR-band maximum to be
17.6+-1.3(stat)+-0.07(sys) rest-frame days for a SN Ia with a VR-band Delta
m_{-10} of 0.52mag. For the redshifts sampled, the observed VR-band
time-of-maximum brightness should be the same as the rest-frame V-band maximum
to within 1.1 rest-frame days.Comment: 35 pages, 18 figures, 15 tables; Higher quality PDF available at
http://ctiokw.ctio.noao.edu/~sm/sm/SNrise/index.html; AJ accepte
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