Ultrahigh-sensitivity optical power monitor for Si photonic circuits

A phototransistor is a promising candidate as an optical power monitor in Si photonic circuits since the internal gain of photocurrent enables high sensitivity. However, state-of-the-art waveguide-coupled phototransistors suffer from a responsivity of lower than $10^3$ A/W, which is insufficient for detecting very low power light. Here, we present a waveguide-coupled phototransistor consisting of an InGaAs ultrathin channel on a Si waveguide working as a gate electrode to increase the responsivity. The Si waveguide gate underneath the InGaAs ultrathin channel enables the effective control of transistor current without optical absorption by the gate metal. As a result, our phototransistor achieved the highest responsivity of approximately $10^6$ A/W among the waveguide-coupled phototransistors, allowing us to detect light of 621 fW propagating in the Si waveguide. The high responsivity and the reasonable response time of approximately 100 $\mu$s make our phototransistor promising as an effective optical power monitor in Si photonics circuits

Liver and intestine transplantation

We have recently achieved several major advances in clinical transplantation, which are addressed separately and include the introduction and development of the new immunosuppressive drug FK506 (Tacrolimus); the feasibility of intestinal transplantation with or without other abdominal organs; and the discovery of the phenomenon of bidirectional cell migration and consequent systemic as well as graft chimerism, which we believe is the essential component for the long-term acceptance of any kind of whole organ graft

History of clinical transplantation

The emergence of transplantation has seen the development of increasingly potent immunosuppressive agents, progressively better methods of tissue and organ preservation, refinements in histocompatibility matching, and numerous innovations is surgical techniques. Such efforts in combination ultimately made it possible to successfully engraft all of the organs and bone marrow cells in humans. At a more fundamental level, however, the transplantation enterprise hinged on two seminal turning points. The first was the recognition by Billingham, Brent, and Medawar in 1953 that it was possible to induce chimerism-associated neonatal tolerance deliberately. This discovery escalated over the next 15 years to the first successful bone marrow transplantations in humans in 1968. The second turning point was the demonstration during the early 1960s that canine and human organ allografts could self-induce tolerance with the aid of immunosuppression. By the end of 1962, however, it had been incorrectly concluded that turning points one and two involved different immune mechanisms. The error was not corrected until well into the 1990s. In this historical account, the vast literature that sprang up during the intervening 30 years has been summarized. Although admirably documenting empiric progress in clinical transplantation, its failure to explain organ allograft acceptance predestined organ recipients to lifetime immunosuppression and precluded fundamental changes in the treatment policies. After it was discovered in 1992 that long-surviving organ transplant recipient had persistent microchimerism, it was possible to see the mechanistic commonality of organ and bone marrow transplantation. A clarifying central principle of immunology could then be synthesized with which to guide efforts to induce tolerance systematically to human tissues and perhaps ultimately to xenografts

History of clinical transplantation

How transplantation came to be a clinical discipline can be pieced together by perusing two volumes of reminiscences collected by Paul I. Terasaki in 1991-1992 from many of the persons who were directly involved. One volume was devoted to the discovery of the major histocompatibility complex (MHC), with particular reference to the human leukocyte antigens (HLAs) that are widely used today for tissue matching.1 The other focused on milestones in the development of clinical transplantation.2 All the contributions described in both volumes can be traced back in one way or other to the demonstration in the mid-1940s by Peter Brian Medawar that the rejection of allografts is an immunological phenomenon.3,4 © 2008 Springer New York

Childhood Mortality Due to Unintentional Injuries in Japan, 2000–2009

This study examined deaths due to unintentional injuries among children in Japan to identify the age groups and sexes at most risk, and the types of injuries, so that effective forms of targeted intervention can be devised. Among children aged 0–14 years, deaths whose underlying causes had been classified under code V01-X59 of the ICD-10 were defined as deaths of children caused by unintentional injuries. Using data from the Vital Statistics 2000–2009 for analysis, we examined the changes in mortality and trends in terms of sex, age, and cause of death. Mortality decreased by 46.2%, from 933 in 2000 to 502 in 2009. The mortality rate among children aged 1–4 years decreased by almost half. The total number of deaths during this decade was 7,362 (boys: 4,690, girls: 2,672). Among the causes of death, the majority were due to “transport accidents”, followed by “other accidental threats to breathing”, and “accidental drowning and submersion”. The characteristics observed in terms of sex, age, and cause of death—that is, deaths from suffocation among infants aged less than 1 year, drowning deaths among boys, and transport accidents involving pedestrians and cyclists—must be addressed as targets for future intervention