Spatially-Coupled Precoded Rateless Codes

Raptor codes are rateless codes that achieve the capacity on the binary erasure channels. However the maximum degree of optimal output degree distribution is unbounded. This leads to a computational complexity problem both at encoders and decoders. Aref and Urbanke investigated the potential advantage of universal achieving-capacity property of proposed spatially-coupled (SC) low-density generator matrix (LDGM) codes. However the decoding error probability of SC-LDGM codes is bounded away from 0. In this paper, we investigate SC-LDGM codes concatenated with SC low-density parity-check codes. The proposed codes can be regarded as SC Hsu-Anastasopoulos rateless codes. We derive a lower bound of the asymptotic overhead from stability analysis for successful decoding by density evolution. The numerical calculation reveals that the lower bound is tight. We observe that with a sufficiently large number of information bits, the asymptotic overhead and the decoding error rate approach 0 with bounded maximum degree

Spatially-Coupled Precoded Rateless Codes with Bounded Degree Achieve the Capacity of BEC under BP decoding

Raptor codes are known as precoded rateless codes that achieve the capacity of BEC. However the maximum degree of Raptor codes needs to be unbounded to achieve the capacity. In this paper, we prove that spatially-coupled precoded rateless codes achieve the capacity with bounded degree under BP decoding

Analysis of Radioactive Elements in Testes of Large Japanese Field Mice Using an Electron Probe Micro-Analyser after the Fukushima Accident

The Fukushima Daiichi nuclear power plant (FDNPP) accident drew global attention to the health risks of radiation exposure. The large Japanese field mice (Apodemus speciosus) are rodents endemic to, and distributed throughout, Japan. This wild rodent live in and around the ex-evacuation zone on the ground surface and/or underground. In this study, we evaluated the effect of chronic radiation exposure associated with FDNPP accident on the testes of large Japanese field mice. Morphological analysis and electron-prove X-ray microanalysis (EPMA) was undertaken on the testes. Morphological analysis of testes based on H&E staining showed that the spermatogenesis was observed normally in the breeding season of wild mice in the heavily contaminated area. However, caesium (Cs) was not detected in all testes of wild mice from FDNPP ex-evacuation zone. In conclusion, even if the testes and the process of spermatogenesis are hypersensitive to radiation, we could not detect radiation effects on the spermatogenesis and Cs in the examined large Japanese field mice testes following chronic radiation exposure associated with the FDNPP accident

Nonmagnetic framboid and associated iron nanoparticles with a space-weathered feature from asteroid Ryugu

リュウグウ試料に初期太陽系の新しい磁気記録媒体を発見～太陽系磁場の新たな研究手法の確立に期待～.京都大学プレスリリース. 2024-04-30.Extraterrestrial minerals on the surface of airless Solar System bodies undergo gradual alteration processes known as space weathering over long periods of time. The signatures of space weathering help us understand the phenomena occurring in the Solar System. However, meteorites rarely retain the signatures, making it impossible to study the space weathering processes precisely. Here, we examine samples retrieved from the asteroid Ryugu by the Hayabusa2 spacecraft and discover the presence of nonmagnetic framboids through electron holography measurements that can visualize magnetic flux. Magnetite particles, which normally provide a record of the nebular magnetic field, have lost their magnetic properties by reduction via a high-velocity (>5 km s⁻¹) impact of a micrometeoroid with a diameter ranging from 2 to 20 μm after destruction of the parent body of Ryugu. Around these particles, thousands of metallic-iron nanoparticles with a vortex magnetic domain structure, which could have recorded a magnetic field in the impact event, are found. Through measuring the remanent magnetization of the iron nanoparticles, future studies are expected to elucidate the nature of the nebular/interplanetary magnetic fields after the termination of aqueous alteration in an asteroid

Local Education Administration under the Executive Model in England : Through Interviews with a Directly-Elected Mayor, Councillors and Officers

In 2000 the executive model was introduced in England, and then the directly-elected mayor system has been adopted in some authorities. The aim of this paper is through interviews in more than 10 authorities to clarify the actual circumstances in authorities with the directly-elected mayor system and the way education administration and decision-making are carried out under the executive model. The author argues that there are various systems whereby backbenchers and people can commit to decisionmaking concerning education whilst executive members have the powerful authority to make decisions

Parental Participation and School Governing Body in England : Parental Right to Participate or School Governance

The author argues that within two streams around the world regarding parental participation system school governing body in England is the system for school governance or school improvement, not for ensuring parental participation from the perspective of parental right/responsibility to education of his / her child. In order to clarify this, after giving a brief theoretical analysis the author describes the actual situation of school governing bodies through his interviews with governors and headteachers and his observation, raising the possibility of the Parents’ Forum system in England as the system for parental participation and suggesting the development of the parental participation system in Japan

The theoretical analysis on the school governing bodies\u27function and role in the school management in England

The purpose of this paper is to clarify the system design about the school governing bodies in England, which is one of models of the school management councils (Gakkou Unei Kyougikai) in Japan, and to get suggestions for Japan. Firstly, in terms of distribution of powers between the headteacher and the governing body, the governing body is dependent on largely headteacher for its decision making. Secondly, in terms of involvement of external authorities, the system is designed as external authorities can play decisive role in the decision making concerning curriculum, personnel, and budget. Then, this paper points out that school management in England is practically getting professionalized including governing bodies though lay governors are formally elected, and that more recent years local councils have been changed to an executive model, sometimes with a directly elected mayor. Taking these circumstances into account, this paper concludes that the existence of school based management is questionable, and that the school governing body system could make it difficult to restrict the power of the central government and to reflect local public opinion on education to the local authority