All-sky LIGO Search for Periodic Gravitational Waves in the Early S5 Data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50--1100 Hz and with the frequency's time derivative in the range -5.0E-9 Hz/s to zero. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semi-coherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 1.E-24 are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 1.0E-6, the search is sensitive to distances as great as 500 pc--a range that could encompass many undiscovered neutron stars, albeit only a tiny fraction of which would likely be rotating fast enough to be accessible to LIGO. This ellipticity is at the upper range thought to be sustainable by conventional neutron stars and well below the maximum sustainable by a strange quark star.Comment: 6 pages, 1 figur

Search for gravitational-wave bursts in the first year of the fifth LIGO science run

We present the results obtained from an all-sky search for gravitational-wave (GW) bursts in the 64-2000 Hz frequency range in data collected by the LIGO detectors during the first year (November 2005 - November 2006) of their fifth science run. The total analyzed livetime was 268.6 days. Multiple hierarchical data analysis methods were invoked in this search. The overall sensitivity expressed in terms of the root-sum-square (rss) strain amplitude h_{rss} for gravitational-wave bursts with various morphologies was in the range of 6 times 10^{-22} Hz^{-1/2} to a few times 10^{-21} Hz^{-1/2}. No GW signals were observed and a frequentist upper limit of 3.6 events per year on the rate of strong GW bursts was placed at the 90% confidence level. As in our previous searches, we also combined this rate limit with the detection efficiency for selected waveform morphologies to obtain event rate versus strength exclusion curves. In sensitivity, these exclusion curves are the most stringent to date.Comment: v3: various figure and text edits; submitted to PRD; 26 page

Search for High Frequency Gravitational Wave Bursts in the First Calendar Year of LIGO's Fifth Science Run

We present an all-sky search for gravitational waves in the frequency range 1 to 6 kHz during the first calendar year of LIGO's fifth science run. This is the first untriggered LIGO burst analysis to be conducted above 3 kHz. We discuss the unique properties of interferometric data in this regime. 161.3 days of triple-coincident data were analyzed. No gravitational events above threshold were observed and a frequentist upper limit of 5.4 events per year on the rate of strong gravitational wave bursts was placed at a 90% confidence level. Implications for specific theoretical models of gravitational wave emission are also discussed.Comment: 13 pages, accepted for publication in Physical Review

Search for gravitational wave ringdowns from perturbed black holes in LIGO S4 data

According to general relativity a perturbed black hole will settle to a stationary configuration by the emission of gravitational radiation. Such a perturbation will occur, for example, in the coalescence of a black hole binary, following their inspiral and subsequent merger. At late times the waveform is a superposition of quasi-normal modes, which we refer to as the ringdown. The dominant mode is expected to be the fundamental mode, l=m=2. Since this is a well-known waveform, matched filtering can be implemented to search for this signal using LIGO data. We present a search for gravitational waves from black hole ringdowns in the fourth LIGO science run S4, during which LIGO was sensitive to the dominant mode of perturbed black holes with masses in the range of 10 Msun to 500 Msun, the regime of intermediate-mass black holes, to distances up to 300 Mpc. We present a search for gravitational waves from black hole ringdowns using data from S4. No gravitational wave candidates were found; we place a 90%-confidence upper limit on the rate of ringdowns from black holes with mass between 85 Msun and 390 Msun in the local universe, assuming a uniform distribution of sources, of 3.2 x 10^{-5} yr^{-1} Mpc^{-3} = 1.6 x 10^{-3}yr^{-1} L_{10}^{-1}, where L_{10} is 10^{10} times the solar blue-light luminosity.Comment: 8 pages, 6 figure

Search for gravitational waves from low mass compact binary coalescence in 186 days of LIGO's fifth science run

We report on a search for gravitational waves from coalescing compact binaries, of total mass between 2 and 35M_☉, using LIGO observations between November 14, 2006 and May 18, 2007. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass. The LIGO cumulative 90%-confidence rate upper limits of the binary coalescence of neutron stars, black holes and black hole-neutron star systems are 1.4 × 10^(-2), 7.3 × 10(-4) and 3.6 × 10(-3) yr(-1) L_10^(-1), respectively, where L_(10_ is 10^(10) times the blue solar luminosit

Search for gravitational waves from low mass compact binary coalescence in 186 days of LIGO's fifth science run

We report on a search for gravitational waves from coalescing compact binaries, of total mass between 2 and 35 Msun, using LIGO observations between November 14, 2006 and May 18, 2007. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass. The LIGO cumulative 90%-confidence rate upper limits of the binary coalescence of neutron stars, black holes and black hole-neutron star systems are 1.4x10^-2, 7.3x10^-4 and 3.6x10^-3 yr^-1L_10^-1 respectively, where L_10 is 10^10 times the blue solar luminosity

Search for gravitational waves from low mass binary coalescences in the first year of LIGO's S5 data

We have searched for gravitational waves from coalescing low mass compact binary systems with a total mass between 2 and 35 Msun and a minimum component mass of 1 Msun using data from the first year of the fifth science run (S5) of the three LIGO detectors, operating at design sensitivity. Depending on mass, we are sensitive to coalescences as far as 150 Mpc from the Earth. No gravitational wave signals were observed above the expected background. Assuming a compact binary objects population with a Gaussian mass distribution representing binary neutron star systems, black hole-neutron star binary systems, and binary black hole systems, we calculate the 90%-confidence upper limit on the rate of coalescences to be 3.9 \times 10^{-2} yr^{-1} L_{10}^{-1}, 1.1 \times 10^{-2} yr^{-1} L_{10}^{-1}, and 2.5 \times 10^{-3} yr^{-1} L_{10}^{-1} respectively, where $L_{10}$ is $10^{10}$ times the blue solar luminosity. We also set improved upper limits on the rate of compact binary coalescences per unit blue-light luminosity, as a function of mass.Comment: 15 pages, 5 figures, 2 tables; changes associated with referee comments, inclusion of recent LIGO calibration data, fixing small error in upper limit calculatio

The design of scaffolds for use in tissue engineering. Part II. Rapid prototyping techniques

Tissue engineering (TE) is an important emerging area in biomedical engineering for creating<br/>biological alternatives for harvested tissues, implants, and prostheses. In TE, a highly<br/>porous artificial extracellular matrix or scaffold is required to accommodate mammalian<br/>cells and guide their growth and tissue regeneration in three-dimension (3D). However, existing<br/>3D scaffolds for TE proved less than ideal for actual applications because they lack<br/>mechanical strength, interconnected channels, and controlled porosity or pores distribution.<br/>In this paper, the authors review the application and advancement of rapid prototyping (RP)<br/>techniques in the design and creation of synthetic scaffolds for use in TE. We also review<br/>the advantages and benefits, and limitations and shortcomings of current RP techniques as<br/>well as the future direction of RP development in TE scaffold fabrication