Verification tests of durable TPS concepts

Titanium multiwall, superalloy honeycomb, and Advanced Carbon-carbon (ACC) multipost Thermal Protection System (TPS) concepts are being developed to provide durable protection for surfaces of future space transportation systems. Verification tests including thermal, vibration, acoustic, water absorption, lightning strike, and aerothermal tests are described. Preliminary results indicate that the three TPS concepts are viable up to a surface temperature in excess of 2300 F

The far field diffraction pattern for corner reflectors with complex reflection coefficients

The far field diffraction pattern of a geometrically perfect corner reflector is examined analytically for normally incident monochromatic light. The states of polarization and the complex amplitudes of the emerging light are expressed through transformation matrices in terms of those of the original incident light for each sextant of the face in a single coordinate system. The analytic expression of the total diffraction pattern is obtained for a circular face. This expression consists of three component functions in addition to the basic Airy function. The coefficient of each function is expressed in terms of complex coefficients of reflectance of the reflecting surface. Some numerical results for different reflecting surfaces, including total internal reflection, are presented. The iso-intensity contours of the diffraction pattern evaluated from the analytical expressions for an uncoated solid corner reflector are also presented along with the photographs of the pattern

Probabilistic Quantum Encoder for Single-Photon Qubits

We describe an experiment in which a physical qubit represented by the polarization state of a single-photon was probabilistically encoded in the logical state of two photons. The experiment relied on linear optics, post-selection, and three-photon interference effects produced by a parametric down-conversion photon pair and a weak coherent state. An interesting consequence of the encoding operation was the ability to observe entangled three-photon Greenberger-Horne-Zeilinger states.Comment: 4 pages, 4 figures; submitted to Phys. Rev.

Nerve growth factor alters microtubule targeting agent-induced neurotransmitter release but not MTA-induced neurite retraction in sensory neurons

Peripheral neuropathy is a dose-limiting side effect of anticancer treatment with the microtubule-targeted agents (MTAs), paclitaxel and epothilone B (EpoB); however, the mechanisms by which the MTAs alter neuronal function and morphology are unknown. We previously demonstrated that paclitaxel alters neuronal sensitivity, in vitro, in the presence of nerve growth factor (NGF). Evidence in the literature suggests that NGF may modulate the neurotoxic effects of paclitaxel. Here, we examine whether NGF modulates changes in neuronal sensitivity and morphology induced by paclitaxel and EpoB. Neuronal sensitivity was assessed using the stimulated release of calcitonin gene-related peptide (CGRP), whereas morphology of established neurites was evaluated using a high content screening system. Dorsal root ganglion cultures, maintained in the absence or presence of NGF, were treated from day 7 to day 12 in culture with paclitaxel (300nM) or EpoB (30nM). Following treatment, the release of CGRP was stimulated using capsaicin or high extracellular potassium. In the presence of NGF, EpoB mimicked the effects of paclitaxel: capsaicin-stimulated release was attenuated, potassium-stimulated release was slightly enhanced and the total peptide content was unchanged. In the absence of NGF, both paclitaxel and EpoB decreased capsaicin- and potassium-stimulated release and the total peptide content, suggesting that NGF may reverse MTA-induced hyposensitivity. Paclitaxel and EpoB both decreased neurite length and branching, and this attenuation was unaffected by NGF in the growth media. These differential effects of NGF on neuronal sensitivity and morphology suggest that neurite retraction is not a causative factor to alter neuronal sensitivity

Investigation of a single-photon source based on quantum interference

We report on an experimental investigation of a single-photon source based on a quantum interference effect first demonstrated by Koashi, Matsuoka, and Hirano [Phys. Rev. A 53, 3621 (1996)]. For certain types of measurement-based quantum information processing applications this technique may be useful as a high rate, but random, source of single photons.Comment: Submitted to the New J. Phys. Focus Issue on "Measurement-based quantum information processing

Proposal for optical parity state re-encoder

We propose a re-encoder to generate a refreshed parity encoded state from an existing parity encoded state. This is the simplest case of the scheme by Gilchrist et al. (Phys. Rev. A 75, 052328). We show that it is possible to demonstrate with existing technology parity encoded quantum gates and teleportation.Comment: 8 pages, 4 figure

Paclitaxel alters the evoked release of calcitonin gene-related peptide from rat sensory neurons in culture

Peripheral neuropathy (PN) is a debilitating and dose-limiting side effect of treatment with the chemotherapeutic agent, paclitaxel. Understanding the effects of paclitaxel on sensory neuronal function and the signaling pathways which mediate these paclitaxel-induced changes in function are critical for the development of therapies to prevent or alleviate the PN. The effects of long-term administration of paclitaxel on the function of sensory neurons grown in culture, using the release of the neuropeptide calcitonin gene-related peptide (CGRP) as an endpoint of sensory neuronal function, were examined. Dorsal root ganglion cultures were treated with low (10 nM) and high (300 nM) concentrations of paclitaxel for 1, 3, or 5 days. Following paclitaxel treatment, the release of CGRP was determined using capsaicin, a TRPV1 agonist; allyl isothiocyanate (AITC), a TRPA1 agonist; or high extracellular potassium. The effects of paclitaxel on the release of CGRP were stimulant-, concentration-, and time-dependent. When neurons were stimulated with capsaicin or AITC, a low concentration of paclitaxel (10nM) augmented transmitter release, whereas a high concentration (300 nM) reduced transmitter release in a time-dependent manner; however, when high extracellular potassium was used as the evoking stimulus, all concentrations of paclitaxel augmented CGRP release from sensory neurons. These results suggest that paclitaxel alters the function of sensory neurons in vitro, and suggest that the mechanisms by which paclitaxel alters neuronal function may include functional changes in TRP channel activity. The described in vitro model will facilitate future studies to identify the signaling pathways by which paclitaxel alters neuronal sensitivity

Demonstration of Non-Deterministic Quantum Logic Operations using Linear Optical Elements

Knill, Laflamme, and Milburn recently showed that non-deterministic quantum logic operations could be performed using linear optical elements, additional photons (ancilla), and post-selection based on the output of single-photon detectors [Nature 409, 46 (2001)]. Here we report the experimental demonstration of two logic devices of this kind, a destructive controlled-NOT (CNOT) gate and a quantum parity check. These two devices can be combined with a pair of entangled photons to implement a conventional (non-destructive) CNOT that succeeds with a probability of 1/4.Comment: 4 pages, 5 figures; Minor change

Two-photon imaging and quantum holography

It has been claimed that ``the use of entangled photons in an imaging system can exhibit effects that cannot be mimicked by any other two-photon source, whatever strength of the correlations between the two photons'' [A. F. Abouraddy, B. E. A. Saleh, A. V. Sergienko, and M. C. Teich, Phys. Rev. Lett. 87, 123602 (2001)]. While we believe that the cited statement is true, we show that the method proposed in that paper, with ``bucket detection'' of one of the photons, will give identical results for entangled states as for appropriately prepared classically correlated states.Comment: 4 pages, 2 figures, REVTe