1,149 research outputs found
ROBAST: Development of a Non-Sequential Ray-Tracing Simulation Library and its Applications in the Cherenkov Telescope Array
We have developed a non-sequential ray-tracing simulation library, ROot-BAsed
Simulator for ray Tracing (ROBAST), which is aimed for wide use in optical
simulations of cosmic-ray (CR) and gamma-ray telescopes. The library is written
in C++ and fully utilizes the geometry library of the ROOT analysis framework.
Despite the importance of optics simulations in CR experiments, no open-source
software for ray-tracing simulations that can be widely used existed. To reduce
the unnecessary effort demanded when different research groups develop multiple
ray-tracing simulators, we have successfully used ROBAST for many years to
perform optics simulations for the Cherenkov Telescope Array (CTA). Among the
proposed telescope designs for CTA, ROBAST is currently being used for three
telescopes: a Schwarzschild--Couder telescope, one of the Schwarzschild--Couder
small-sized telescopes, and a large-sized telescope (LST). ROBAST is also used
for the simulations and the development of hexagonal light concentrators that
has been proposed for the LST focal plane. By fully utilizing the ROOT geometry
library with additional ROBAST classes, building complex optics geometries that
are typically used in CR experiments and ground-based gamma-ray telescopes is
possible. We introduce ROBAST and show several successful applications for CTA.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
ROBAST: Development of a ROOT-Based Ray-Tracing Library for Cosmic-Ray Telescopes and its Applications in the Cherenkov Telescope Array
We have developed a non-sequential ray-tracing simulation library, ROOT-based
simulator for ray tracing (ROBAST), which is aimed to be widely used in optical
simulations of cosmic-ray (CR) and gamma-ray telescopes. The library is written
in C++, and fully utilizes the geometry library of the ROOT framework. Despite
the importance of optics simulations in CR experiments, no open-source software
for ray-tracing simulations that can be widely used in the community has
existed. To reduce the dispensable effort needed to develop multiple
ray-tracing simulators by different research groups, we have successfully used
ROBAST for many years to perform optics simulations for the Cherenkov Telescope
Array (CTA). Among the six proposed telescope designs for CTA, ROBAST is
currently used for three telescopes: a Schwarzschild-Couder (SC) medium-sized
telescope, one of SC small-sized telescopes, and a large-sized telescope (LST).
ROBAST is also used for the simulation and development of hexagonal light
concentrators proposed for the LST focal plane. Making full use of the ROOT
geometry library with additional ROBAST classes, we are able to build the
complex optics geometries typically used in CR experiments and ground-based
gamma-ray telescopes. We introduce ROBAST and its features developed for CR
experiments, and show several successful applications for CTA.Comment: Accepted for publication in Astroparticle Physics. 11 pages, 10
figures, 4 table
Nucleon mean free path in nuclear matter based on nuclear Schwinger-Dyson formalism
A mean free path of nucleon moving through nuclear matter with kinetic energy
of more than 100MeV is formulated based on the bare vertex nuclear
Schwinger-Dyson (BNSD) method in the Walecka model. The self-energy which is
derived from the higher order diagrams more than the forth order includes the
Feynman part of propagator of energetic nucleon and grows up rapidly as an
increase of kinetic energy. To avoid too large growth of these diagrams, meson
propagators are modified by introducing some form factors to take account of a
internal structure of hadron. It is confirmed that the mean free path
calculated by the BNSD method agrees good with experimental data if a
reasonable form factor is chosen, i.e., a dipole (quadrupole) type of form
factor with a cut-off parameter about 750 MeV 1000 MeV (1200 MeV
1500 MeV)
Coupling of ultrathin tapered fibers with high-Q microsphere resonators at cryogenic temperatures and observation of phase-shift transition from undercoupling to overcoupling
We cooled ultrathin tapered fibers to cryogenic temperatures and controllably
coupled them with high-Q microsphere resonators at a wavelength close to the
optical transition of diamond nitrogen vacancy centers. The 310-nm-diameter
tapered fibers were stably nanopositioned close to the microspheres with a
positioning stability of approximately 10 nm over a temperature range of 7-28
K. A cavity-induced phase shift was observed in this temperature range,
demonstrating a discrete transition from undercoupling to overcoupling
Vacuum Effects and Compressional Properties of Nuclear Matter in Cutoff Field Theory
Including the vacuum effects, the compressional properties of nuclear matter
are studied in the cutoff field theory. Under the Hartree approximation, the
low-energy effective Lagrangian is derived in the framework of the
renormalization group methods. The coefficients are determined in a way where
the physical results hardly depend on the value of the cutoff which is
conveniently introduced into the theory. It is shown that, to reproduce the
empirical data of the nucleus incompressibility, the compressibility of the
nuclear matter is favorable to be 250350MeV.Comment: PACS numbers, 21.65.+
Pediatric growing teratoma syndrome of the ovary A case report and review of the literature
Rationale:
Growing teratoma syndrome is defined as an increase in tumor size during or after systemic chemotherapy for germ cell tumors. These cases involve normal tumor maker levels and histological features of only mature teratoma. We report a rare case of an ovarian immature teratoma in a Japanese child that was diagnosed as growing teratoma syndrome.
Patient concerns:
A 12-year-old girl presented a painful abdominal mass. She underwent left salpingo-oophorectomy for grade 1 immature teratoma in the left ovary. She did not undergo additional chemotherapy or radiotherapy. Four months later, she presented with grade 3 immature teratoma disseminated into the abdomen and pelvis. Chemotherapy resulted in the tumor maker levels returning to their normal ranges, although the tumors had grown slightly.
Diagnosis:
The specimens resected by laparotomy after the chemotherapy consisted of mature tissue predominantly, although primitive neuroepithelium was observed in a small part of the specimen. The pathological diagnosis was grade 1 immature teratoma, notwithstanding the clinical diagnosis was growing teratoma syndrome based on the clinical features and pathogenesis.
Interventions:
Laparotomy was performed at 7 months after the first operation, with resection of various tumors as well as the rectum, sigmoid colon, residual left fallopian duct, and a small part of the ileum and omentum. Some small tumors at the parietal peritoneum were ablated, although many tiny tumors around the uterus were left untreated.
Outcomes:
The patient has been free from recurrence for 5 years.
Lessons:
Growing teratoma syndrome can develop in children, and their tumor size is comparable to that in adolescents and adults. Furthermore, development of growing teratoma syndrome from a primary germ cell tumor is presumably faster in children than in adolescents and adults. Complete resection of all growing teratoma tissue is recommended, although fertility-sparing surgery should be considered when possible
Mathematical aspects of the Digital Annealer's simulated annealing algorithm
The Digital Annealer is a CMOS hardware designed by Fujitsu Laboratories for
high-speed solving of Quadratic Unconstrained Binary Optimization (QUBO)
problems that could be difficult to solve by means of existing general-purpose
computers. In this paper, we present a mathematical description of the
first-generation Digital Annealer's Algorithm from the Markov chain theory
perspective, establish a relationship between its stationary distribution with
the Gibbs-Boltzmann distribution, and provide a necessary and sufficient
condition on its cooling schedule that ensures asymptotic convergence to the
ground states
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