232 research outputs found
High-efficiency, single-stage 7-kHz high-average-power ultrafast laser system
Includes bibliographical references (page 467).We demonstrate a simple and practical single-stage ultrafast laser amplifier system that operates at a repetition frequency from 1 to 10 kHz, with millijoule pulse energy and as much as 13 W of average power. The repetition rate can be adjusted continuously from 1 to 10 kHz by new all-solid-state pump laser technology. This is to our knowledge the highest average power ever obtained from a single-stage ultrafast laser amplifier system. This laser will significantly increase the average power and the repetition rate that is easily accessible for high-field experiments such as coherent x-ray generation or for laser-synchrotron studies
The Allen Telescope Array: The First Widefield, Panchromatic, Snapshot Radio Camera for Radio Astronomy and SETI
The first 42 elements of the Allen Telescope Array (ATA-42) are beginning to
deliver data at the Hat Creek Radio Observatory in Northern California.
Scientists and engineers are actively exploiting all of the flexibility
designed into this innovative instrument for simultaneously conducting surveys
of the astrophysical sky and conducting searches for distant technological
civilizations. This paper summarizes the design elements of the ATA, the cost
savings made possible by the use of COTS components, and the cost/performance
trades that eventually enabled this first snapshot radio camera. The
fundamental scientific program of this new telescope is varied and exciting;
some of the first astronomical results will be discussed.Comment: Special Issue of Proceedings of the IEEE: "Advances in Radio
Telescopes", Baars,J. Thompson,R., D'Addario, L., eds, 2009, in pres
Identification and Characterization of Optimal Gene Expression Markers for Detection of Breast Cancer Metastasis
Sentinel lymph node (SLN) status is highly predictive of
overall axillary lymph node involvement in breast cancer.
Historically, SLN-positive patients have undergone
axillary lymph node dissection in a second surgery.
Intraoperative SLN analysis could reduce the cost and
complications of a second surgery; however, existing
histopathological methods lack standardization and exhibit
poor sensitivity. Rapid molecular methods may
lead to improved intraoperative diagnosis of SLN metastasis.
In this study,we used a genome-wide gene expression
analysis of breast and other tissues to identify
seven putative markers for detecting breast cancer metastasis.
We assessed the utility of these markers for
identifying clinically actionable metastases in lymph
nodes through reverse transcriptase-polymerase chain
reaction analysis of SLNs from 254 breast cancer patients.
Polymerase chain reaction signals were compared
to pathology on a per-patient basis. The optimal
two-gene combination, mammaglobin and cytokeratin
19, detected clinically actionable metastasis in breast
SLNs with 90% sensitivity and 94% specificity. Application
of stringent criteria for identifying presumptive
hematoxylin- and eosin-positive samples increased sensitivity
and specificity to 91 and 97%, respectively. This
study represents the first comprehensive demonstration
of the utility of gene expression markers for detecting
clinically actionable breast metastases. An intraoperative
molecular assay using these markers has the
potential to significantly reduce second surgeries for
patients undergoing SLN dissection. Originally published Journal of Molecular Diagnostics, Vol. 7, No. 3, Aug 200
Asymmetric shallow mantle structure beneath the Hawaiian Swell—evidence from Rayleigh waves recorded by the PLUME network
Author Posting. © The Author(s), 2011. This article is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 187 (2011): 1725–1742, doi:10.1111/j.1365-246X.2011.05238.x.We present models of the 3-D shear velocity structure of the lithosphere and asthenosphere beneath the Hawaiian hotspot and surrounding region. The models are derived from long-period Rayleigh-wave phase velocities that were obtained from the analysis of seismic recordings collected during two year-long deployments for the Hawaiian Plume-Lithosphere Undersea Mantle Experiment. For this experiment, broad-band seismic sensors were deployed at nearly 70 seafloor sites as well as 10 sites on the Hawaiian Islands. Our seismic images result from a two-step inversion of path-averaged dispersion curves using the two-station method. The images reveal an asymmetry in shear velocity structure with respect to the island chain, most notably in the lower lithosphere at depths of 60 km and greater, and in the asthenosphere. An elongated, 100-km-wide and 300-km-long low-velocity anomaly reaches to depths of at least 140 km. At depths of 60 km and shallower, the lowest velocities are found near the northern end of the island of Hawaii. No major velocity anomalies are found to the south or southeast of Hawaii, at any depth. The low-velocity anomaly in the asthenosphere is consistent with an excess temperature of 200–250 °C and partial melt at the level of a few percent by volume, if we assume that compositional variations as a result of melt extraction play a minor role. We also image small-scale low-velocity anomalies within the lithosphere that may be associated with the volcanic fields surrounding the Hawaiian Islands.This research was financed by the National Science Foundation under
grants OCE-00-02470 and OCE-00-02819. Markee was partly
sponsored by a SIO graduate student fellowship
- …