The Role of Lambda(1405) in Kaon-Proton Interactions

S-wave $K^-p$ scattering into various channels near threshold are analyzed in heavy-baryon chiral perturbation theory with $\Lambda (1405)$ introduced as an independent field. This is the approach that predicted the critical density $2<=\rho_c/\rho_0 <=3$ for negatively charged kaon condensation. We show that chiral perturbation expansion treating the $\Lambda (1405)$ as elementary is consistent with {\it all} threshold data including a double-charge-exchange process suppressed at leading order of chiral expansion in the absence of the $\Lambda (1405)$. We also discuss S-wave $K^+ p$ scattering phase shifts at low energy.Comment: 12 pages, epsfig.sty, 1 figure (uuencoded

Kaon-Nucleon Scattering from Chiral Lagrangians

The s-wave $K^{\pm}N$ scattering amplitude is computed up to one-loop order corresponding to next-to-next-to-leading order (or N$^2$LO in short) with a heavy-baryon effective chiral Lagrangian. Constraining the low-energy constants by on-shell scattering lengths, we obtain contributions of each chiral order up to N$^2$LO and find that the chiral corrections are ``natural" in the sense of viable effective field theories. We have also calculated off-shell $s$-wave $K^-N$ scattering amplitudes relevant to kaonic atoms and $K^-$ condensation in ``nuclear star" matter including the effect of $\Lambda (1405)$. The $K^-p$ amplitude is found to be quite sensitive to the intermediate $\Lambda (1405)$ contribution, while the $K^-n$ amplitude varies smoothly with the C.M. energy. The crossing-even one-loop corrections are found to play an important role in determining the higher-order chiral corrections.Comment: 14 pages and 2 figures(LaTeX), SNUTP-93-81. (References are added in the reference [21]

A Highly Sensitive Enzyme-Amplified Immunosensor Based on a Nanoporous Niobium Oxide (Nb2O5) Electrode

We report on the development of an enzyme-amplified sandwich-type immunosensor based on a thin gold film sputtered on an anodic nanoporous niobium oxide (Au@Nb2O5) electrode. The electrocatalytic activity of enzymatically amplified electroactive species and a stable electrode consisting of Au@Nb2O5 were used to obtain a powerful signal amplification of the electrochemical immunobiosensor. The method using this electrochemical biosensor based on an Au@Nb2O5 electrode provides a much better performance than those based on conventional bulk gold or niobium oxide electrodes. Our novel approach does not require any time-consuming cleaning steps to yield reproducible electrochemical signals. In addition, the strong adhesion of gold films on the niobium oxide electrodes offers a very stable substrate during electrochemical biosensing. Cyclic voltammetry measurements indicate that non-specific binding of proteins to the modified Au@Nb2O5 surface is sufficiently low to be ignored in the case of our novel system. Finally, we demonstrated the ability of the biosensor based on an Au@Nb2O5 offering the enhanced performance with a high resolution and sensitivity. Therefore, it is expected that the biosensor based on an Au@Nb2O5 has great potential for highly efficient biological devices

Kaon Condensation in Dense Stellar Matter

This talk is based on work done in collaboration with G.E. Brown and D.-P. Min on kaon condensation in dense baryonic medium treated in chiral perturbation theory using heavy-baryon formalism. It contains, in addition to what was recently published, some new results based on the analysis on kaonic atoms by Friedman, Gal and Batty and a discussion on a renormalization-group analysis to meson condensation made together with H.K. Lee and Sin. Negatively charged kaons are predicted to condense at the critical density 2\lsim \rho/\rho_0\lsim 4, in the range to allow all the intriguing new phenomena predicted by Brown and Bethe to take place in compact star matter.Comment: 16 pages, epsfig.sty, 1 figure(uuencoded

Finite Element Analysis of Bone and Experimental Validation

This chapter describes the application of the finite element (FE) method to bone tissues. The aspects that differ the most between bone and other materials’ FE analysis are the type of elements used, constitutive models, and experimental validation. These aspects are looked at from a historical evolution stand point. Several types of elements can be used to simulate similar bone structures and within the same analysis many types of elements may be needed to realistically simulate an anatomical part. Special attention is made to constitutive models, including the use of density-elasticity relationships made possible through CT-scanned images. Other more complex models are also described that include viscoelasticity and anisotropy. The importance of experimental validation is discussed, describing several methods used by different authors in this challenging field. The use of cadaveric human bones is not always possible or desirable and other options are described, as the use of animal or artificial bones. Strain and strain rate measuring methods are also discussed, such as rosette strain gauges and optical devices.publishe

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta