6 research outputs found
The RRAT Trap: Interferometric Localization of Radio Pulses from J0628+0909
We present the first blind interferometric detection and imaging of a
millisecond radio transient with an observation of transient pulsar J0628+0909.
We developed a special observing mode of the Karl G. Jansky Very Large Array
(VLA) to produce correlated data products (i.e., visibilities and images) on a
time scale of 10 ms. Correlated data effectively produce thousands of beams on
the sky that can localize sources anywhere over a wide field of view. We used
this new observing mode to find and image pulses from the rotating radio
transient (RRAT) J0628+0909, improving its localization by two orders of
magnitude. Since the location of the RRAT was only approximately known when
first observed, we searched for transients using a wide-field detection
algorithm based on the bispectrum, an interferometric closure quantity. Over 16
minutes of observing, this algorithm detected one transient offset roughly 1'
from its nominal location; this allowed us to image the RRAT to localize it
with an accuracy of 1.6". With a priori knowledge of the RRAT location, a
traditional beamforming search of the same data found two, lower significance
pulses. The refined RRAT position excludes all potential multiwavelength
counterparts, limiting its optical luminosity to L_i'<1.1x10^31 erg/s and
excluding its association with a young, luminous neutron star.Comment: Submitted to ApJ, 7 pages, 5 figure
O-Band Subwavelength Grating Filters in a Monolithic Photonics Technology
The data communications industry has begun transitioning from electrical to
optical interconnects in datacenters in order to overcome performance
bottlenecks and meet consumer needs. To mitigate the costs associated with this
change and achieve performance for 5G and beyond, it is crucial to explore
advanced photonic devices that can enable high-bandwidth interconnects via
wavelength-division multiplexing (WDM) in photonic integrated circuits.
Subwavelength grating (SWG) filters have shown great promise for WDM
applications. However, the small feature sizes necessary to implement these
structures have prohibited them from penetrating into industrial applications.
To explore the manufacturability and performance of SWG filters in an
industrial setting, we fabricate and characterize O-band subwavelength grating
filters using the monolithic photonics technology at GLOBALFOUNDRIES (GF). We
demonstrate a low drop channel loss of -1.2 dB with a flat-top response, a high
extinction ratio of -30 dB, a 3 dB channel width of 5 nm and single-source
thermal tunability without shape distortion. This filter structure was designed
using elements from the product design kit provided by GF and functions in a
compact footprint of 0.002 mm2 with a minimum feature size of 150 nm.Comment: 4 pages, 3 figure
Photo-hydrogen-evolving activity of chloro(terpyridine)platinum(ii): a single-component molecular photocatalyst
Effects of once-weekly exenatide on cardiovascular outcomes in type 2 diabetes
BACKGROUND: The cardiovascular effects of adding once-weekly treatment with exenatide to usual care in patients with type 2 diabetes are unknown. METHODS: We randomly assigned patients with type 2 diabetes, with or without previous cardiovascular disease, to receive subcutaneous injections of extended-release exenatide at a dose of 2 mg or matching placebo once weekly. The primary composite outcome was the first occurrence of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke. The coprimary hypotheses were that exenatide, administered once weekly, would be noninferior to placebo with respect to safety and superior to placebo with respect to efficacy. RESULTS: In all, 14,752 patients (of whom 10,782 [73.1%] had previous cardiovascular disease) were followed for a median of 3.2 years (interquartile range, 2.2 to 4.4). A primary composite outcome event occurred in 839 of 7356 patients (11.4%; 3.7 events per 100 person-years) in the exenatide group and in 905 of 7396 patients (12.2%; 4.0 events per 100 person-years) in the placebo group (hazard ratio, 0.91; 95% confidence interval [CI], 0.83 to 1.00), with the intention-to-treat analysis indicating that exenatide, administered once weekly, was noninferior to placebo with respect to safety (P<0.001 for noninferiority) but was not superior to placebo with respect to efficacy (P=0.06 for superiority). The rates of death from cardiovascular causes, fatal or nonfatal myocardial infarction, fatal or nonfatal stroke, hospitalization for heart failure, and hospitalization for acute coronary syndrome, and the incidence of acute pancreatitis, pancreatic cancer, medullary thyroid carcinoma, and serious adverse events did not differ significantly between the two groups. CONCLUSIONS: Among patients with type 2 diabetes with or without previous cardiovascular disease, the incidence of major adverse cardiovascular events did not differ significantly between patients who received exenatide and those who received placebo