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Neuroscience is at a crossroads. Great effort is being invested into deciphering specific neural interactions and circuits. At the same time, there exist few general theories or principles that explain brain function. We attribute this disparity, in part, to limitations in current methodologies. Traditional neurophysiological approaches record the(More)
We design and implement a novel class of highly precise network instrumentation and apply this tool to perform the first exact packet-timing measurements of a wide-area network ever undertaken, capturing 10 Gigabit Ethernet packets in flight on optical fiber. Through principled design, we improve timing precision by two to six orders of magnitude over(More)
  • Scott S. Howard, Adam Straub, Nicholas Horton, Demirhan Kobat, Chris Xu
  • 2013
Multiphoton microscopy (MPM) is widely used for optical sectioning deep in scattering tissue, in vivo [1–2]. Phosphorescence lifetime imaging microscopy (PLIM) [3] is a powerful technique for obtaining biologically relevant chemical information through Förster resonance energy transfer and phosphorescence quenching [4–5]. Point-measurement PLIM [6] of(More)
In this article we bring together opposing international relations theories to better understand U+S+ foreign policy, in particular foreign trade and aid+ Using votes in the U+S+ House of Representatives from 1979–2004, we explore different theoretical predictions about preferences for foreign economic policy+ We assess the impact of domestic factors,(More)
We characterize long (up to 285 mm) gradient index (GRIN) lens endoscope systems for multiphoton imaging. We fabricate a portable, rigid endoscope system suitable for imaging unstained tissues, potentially deep within the body, using a GRIN lens system of 1 mm diameter and 8 cm length. The portable device is capable of imaging a ~200 µm diameter field of(More)
We demonstrate improved efficiency and dynamic range for two-photon absorption at 1.5 microm in a photoelectron-counting GaAs photomultiplier tube. cw laser measurements show pure two-photon absorption occurring in the device from average powers of 1.3 microW to nearly 1 mW. We use the detector to implement an autocorrelator with peak-power x average-power(More)
We present a compact and portable three-photon gradient index (GRIN) lens endoscope system suitable for imaging of unstained tissues, potentially deep within the body, using a GRIN lens system of 1 mm diameter and 8 cm length. The lateral and axial resolution in water is 1.0 μm and 9.5 μm, respectively. The ~200 μm diameter field of view is imaged at 2(More)
  • Chris Xu, Josephine Alexa Potter, Christopher David Carter, Clayton Miles Cooper Lang
  • 2014
OBJECTIVE Tumoral calcinosis is an uncommon lesion, composed of ectopic calcified tissue, most commonly seen in the large joints of the hips, knees, shoulders, and elbows. The involvement of the hand in a healthy patient is extremely rare, and therefore this condition can cause diagnostic confusion. The purpose of this report is to describe one case of(More)
We demonstrate a fiber-based, three-color femtosecond source for simultaneous imaging of three fluorescent proteins (FPs) using two-photon fluorescence microscopy (2PM). The three excitation wavelengths at 775 nm, 864 nm and 950 nm, are obtained through second harmonic generation (SHG) of the 1550-nm pump laser and the 1728-nm and 1900-nm solitons generated(More)