Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.
Impaired or damaged blood vessels can occur at all levels in the hierarchy of vascular systems from large vasculatures such as arteries and veins to meso‐ and microvasculatures such as arterioles, venules, and capillary networks. Vascular tissue engineering has become a promising approach for fabricating small‐diameter vascular grafts for occlusive arteries. Vascularized tissue engineering aims to fabricate meso‐ and microvasculatures for the prevascularization of engineered tissues and organs. The ideal small‐diameter vascular graft is biocompatible, bridgeable, and mechanically robust to maintain patency while promoting tissue remodeling. The desirable fabricated meso‐ and microvasculatures should rapidly integrate with the host blood vessels and allow nutrient and waste exchange throughout the construct after implantation. A number of techniques used, including engineering‐based and cell‐based approaches, to fabricate these synthetic vasculatures are herein explored, as well as the techniques developed to fabricate hierarchical structures that comprise multiple levels of vasculature.
With the advent of positron emission tomography (PET), a variety of techniques have been developed to measure local cerebral blood flow (LCBF) noninvasively in humans. A potential class of techniques, which includes linear least squares (LS), linear weighted least squares (WLS), linear generalized least squares (GLS), and linear generalized weighted least squares (GWLS), is proposed. The statistical characteristics of these methods are examined by computer simulation. The authors present a comparison of these four methods with two other rapid estimation techniques developed by Huang et al. (1982) and Alpert (1984), and two classical methods, the unweighted and weighted nonlinear least squares regression. The results show that these methods can take full advantage of the contribution from the fine temporal sampling data of modern tomographs, and thus provide statistically reliable estimates that are comparable to those obtained from nonlinear LS regression. These methods also have high computational efficiency, and the parameters can be estimated directly from operational equations in one single step. Therefore, they can potentially be used in image-wide estimation of local cerebral blood flow and distribution volume with PET.
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