California Institute of Technology

About: California Institute of Technology is a education organization based out in Pasadena, California, United States. It is known for research contribution in the topics: Galaxy & Redshift. The organization has 57649 authors who have published 146691 publications receiving 8620287 citations. The organization is also known as: Caltech & Cal Tech.

Evidence of RNAi in humans from systemically administered siRNA via targeted nanoparticles

Abstract: Therapeutics that are designed to engage RNA interference (RNAi) pathways have the potential to provide new, major ways of imparting therapy to patients. Long, double-stranded RNAs were first shown to mediate RNAi in Caenorhabditis elegans, and the potential use of RNAi for human therapy has been demonstrated by the finding that small interfering RNAs (siRNAs; approximately 21-base-pair double-stranded RNA) can elicit RNAi in mammalian cells without producing an interferon response. We are at present conducting the first in-human phase I clinical trial involving the systemic administration of siRNA to patients with solid cancers using a targeted, nanoparticle delivery system. Here we provide evidence of inducing an RNAi mechanism of action in a human from the delivered siRNA. Tumour biopsies from melanoma patients obtained after treatment show the presence of intracellularly localized nanoparticles in amounts that correlate with dose levels of the nanoparticles administered (this is, to our knowledge, a first for systemically delivered nanoparticles of any kind). Furthermore, a reduction was found in both the specific messenger RNA (M2 subunit of ribonucleotide reductase (RRM2)) and the protein (RRM2) levels when compared to pre-dosing tissue. Most notably, we detect the presence of an mRNA fragment that demonstrates that siRNA-mediated mRNA cleavage occurs specifically at the site predicted for an RNAi mechanism from a patient who received the highest dose of the nanoparticles. Together, these data demonstrate that siRNA administered systemically to a human can produce a specific gene inhibition (reduction in mRNA and protein) by an RNAi mechanism of action.

Two-Dimensional Photonic Band-Gap Defect Mode Laser

Abstract: A laser cavity formed from a single defect in a two-dimensional photonic crystal is demonstrated. The optical microcavity consists of a half wavelength–thick waveguide for vertical confinement and a two-dimensional photonic crystal mirror for lateral localization. A defect in the photonic crystal is introduced to trap photons inside a volume of 2.5 cubic half-wavelengths, approximately 0.03 cubic micrometers. The laser is fabricated in the indium gallium arsenic phosphide material system, and optical gain is provided by strained quantum wells designed for a peak emission wavelength of 1.55 micrometers at room temperature. Pulsed lasing action has been observed at a wavelength of 1.5 micrometers from optically pumped devices with a substrate temperature of 143 kelvin.

Local detection of electromagnetic energy transport below the diffraction limit in metal nanoparticle plasmon waveguides.

Abstract: Achieving control of light-material interactions for photonic device applications at nanoscale dimensions will require structures that guide electromagnetic energy with a lateral mode confinement below the diffraction limit of light. This cannot be achieved by using conventional waveguides or photonic crystals. It has been suggested that electromagnetic energy can be guided below the diffraction limit along chains of closely spaced metal nanoparticles that convert the optical mode into non-radiating surface plasmons. A variety of methods such as electron beam lithography and self-assembly have been used to construct metal nanoparticle plasmon waveguides. However, all investigations of the optical properties of these waveguides have so far been confined to collective excitations and direct experimental evidence for energy transport along plasmon waveguides has proved elusive. Here we present observations of electromagnetic energy transport from a localized subwavelength source to a localized detector over distances of about 0.5 μm in plasmon waveguides consisting of closely spaced silver rods. The waveguides are excited by the tip of a near-field scanning optical microscope, and energy transport is probed by using fluorescent nanospheres.

The 2dF Galaxy Redshift Survey: spectra and redshifts

Abstract: The 2dF Galaxy Redshift Survey (2dFGRS) is designed to measure redshifts for approximately 250 000 galaxies. This paper describes the survey design, the spectroscopic observations, the redshift measurements and the survey data base. The 2dFGRS uses the 2dF multifibre spectrograph on the Anglo-Australian Telescope, which is capable of observing 400 objects simultaneously over a 2° diameter field. The source catalogue for the survey is a revised and extended version of the APM galaxy catalogue, and the targets are galaxies with extinction-corrected magnitudes brighter than b J = 19.45. The main survey regions are two declination strips, one in the southern Galactic hemisphere spanning 80° × 15° around the SGP, and the other in the northern Galactic hemisphere spanning 75° × 10° along the celestial equator; in addition, there are 99 fields spread over the southern Galactic cap. The survey covers 2000 deg 2 and has a median depth of z = 0.11. Adaptive tiling is used to give a highly uniform sampling rate of 93 per cent over the whole survey region. Redshifts are measured from spectra covering 3600-8000 A at a two-pixel resolution of 9.0 A and a median S/N of 13 pixel - 1 . All redshift identifications are visually checked and assigned a quality parameter Q in the range 1-5; Q ≥ 3 redshifts are 98.4 per cent reliable and have an rms uncertainty of 85 km s - 1 . The overall redshift completeness for Q ≥ 3 redshifts is 91.8 per cent, but this varies with magnitude from 99 per cent for the brightest galaxies to 90 per cent for objects at the survey limit. The 2dFGRS data base is available on the World Wide Web at http://www. mso.anu.edu.au/2dFGRS.