A Note on Liquidity Risk Management

When a firm is unable to roll over its debt, it may have to seek more expensive sources of financing or even liquidate its assets. This paper provides a normative analysis of minimizing such rollover risk, through the optimal dynamic choice of the maturity structure of debt. The objective of a firm with long-term assets is to maximize the effective maturity of its liabilities across several refinancing cycles, rather than to maximize the maturity of the current bonds outstanding. An advantage of short-term financing is that a firm, while in good financial health, can readjust its maturity structure more quickly in response to changes in its asset value.

Preoperative risk stratification of lymph node metastasis for non-functional pancreatic neuroendocrine neoplasm: An international dual-institutional study

BACKGROUND: /Objectives: Although the presence of lymph node metastasis (LNM) defines malignant potential, preoperative prediction of LNM has not been established for non-functional pancreatic neuroendocrine neoplasm (NF-PNEN). We sought to develop a prediction system using only preoperatively available factors that would stratify the risk of LNM for NF-PNEN. METHODS: We retrospectively reviewed patients who underwent R0/1 resection of NF-PNEN at Kyoto University (2007-2019) and the University of California, San Francisco (2010-2019). Risk stratification of LNM was developed using preoperative factors by the logistic regression analysis. Long-term outcomes were compared across the risk groups. RESULTS: A total of 131 patients were included in this study. Lymph nodes were pathologically examined in 116 patients, 23 (20%) of whom had LNM. Radiological tumor size [1.5-3.5 cm (odds ratio: 13.5, 95% confidence interval: 1.77-398) and >3.5 cm (72.4, 9.06-2257) against ≤1.5 cm], <50% cystic component (8.46 × 10^6, 1.68 × 10^106-), and dilatation of main pancreatic duct ≥5 mm (31.2, 3.94-702) were independently associated with LNM. When patients were classified as the low-risk (43 patients), intermediate-risk (44 patients), and high-risk groups (29 patients), proportions of LNM differed significantly across the groups (0%, 14%, and 59%, respectively). Recurrence-free survival (RFS) of the low- and intermediate-risk groups were significantly better than that of the high-risk group (5-year RFS rates of 92.2%, 85.4%, and 47.1%, respectively). CONCLUSIONS: The prediction system using preoperative radiological factors stratifies the risk of LNM for NF-PNEN. This stratification helps to predict malignant potential and determine the surgical procedure and necessity of regional lymphadenectomy

Development of an experimental platform for the investigation of laser-plasma interaction in conditions relevant to shock ignition regime

The shock ignition (SI) approach to inertial confinement fusion is a promising scheme for achieving energy production by nuclear fusion. SI relies on using a high intensity laser pulse (≈1016 W/cm2, with a duration of several hundred ps) at the end of the fuel compression stage. However, during laser-plasma interaction (LPI), several parametric instabilities, such as stimulated Raman scattering and two plasmon decay, nonlinearly generate hot electrons (HEs). The whole behavior of HE under SI conditions, including their generation, transport, and final absorption, is still unclear and needs further experimental investigation. This paper focuses on the development of an experimental platform for SI-related experiments, which simultaneously makes use of multiple diagnostics to characterize LPI and HE generation, transport, and energy deposition. Such diagnostics include optical spectrometers, streaked optical shadowgraph, an x-ray pinhole camera, a two-dimensional x-ray imager, a Cu Kα line spectrometer, two hot-electron spectrometers, a hard x-ray (bremsstrahlung) detector, and a streaked optical pyrometer. Diagnostics successfully operated simultaneously in single-shot mode, revealing the features of HEs under SI-relevant conditions.T. Tamagawa, Y. Hironaka, K. Kawasaki, D. Tanaka, T. Idesaka, N. Ozaki, R. Kodama, R. Takizawa, S. Fujioka, A. Yogo, D. Batani, Ph. Nicolai, G. Cristoforetti, P. Koester, L. A. Gizzi, and K. Shigemori, "Development of an experimental platform for the investigation of laser–plasma interaction in conditions relevant to shock ignition regime", Review of Scientific Instruments 93, 063505 (2022) https://doi.org/10.1063/5.008996

Proof-of-principle experiment for laser-driven cold neutron source

The scientific and technical advances continue to support novel discoveries by allowing scientists to acquire new insights into the structure and properties of matter using new tools and sources. Notably, neutrons are among the most valuable sources in providing such a capability. At the Institute of Laser Engineering, Osaka, the first steps are taken towards the development of a table-top laser-driven neutron source, capable of producing a wide range of energies with high brightness and temporal resolution. By employing a pure hydrogen moderator, maintained at cryogenic temperature, a cold neutron ($$\le 25\hbox { meV}$$≤25meV) flux of $$\sim 2\times 10^3\hbox { n/cm}^2$$∼2×103n/cm2/pulse was measured at the proximity of the moderator exit surface. The beam duration of hundreds of ns to tens of \upmu \hbox {s}μsis evaluated for neutron energies ranging from 100s keV down to meV via Monte-Carlo techniques. Presently, with the upcoming J-EPoCH high repetition rate laser at Osaka University, a cold neutron flux in orders of $$\sim 1\times 10^{9}\hbox { n/cm}^2/\hbox {s}$$∼1×109n/cm2/sis expected to be delivered at the moderator in a compact beamline

Enhancing laser beam performance by interfering intense laser beamlets

Increasing the laser energy absorption into energetic particle beams represents a longstanding quest in intense laser-plasma physics. During the interaction with matter, part of the laser energy is converted into relativistic electron beams, which are the origin of secondary sources of energetic ions, γ-rays and neutrons. Here we experimentally demonstrate that using multiple coherent laser beamlets spatially and temporally overlapped, thus producing an interference pattern in the laser focus, significantly improves the laser energy conversion efficiency into hot electrons, compared to one beam with the same energy and nominal intensity as the four beamlets combined. Two-dimensional particle-in-cell simulations support the experimental results, suggesting that beamlet interference pattern induces a periodical shaping of the critical density, ultimately playing a key-role in enhancing the laser-to-electron energy conversion efficiency. This method is rather insensitive to laser pulse contrast and duration, making this approach robust and suitable to many existing facilities