A 15.65 solar mass black hole in an eclipsing binary in the nearby spiral galaxy Messier 33

Stellar-mass black holes are discovered in X-ray emitting binary systems, where their mass can be determined from the dynamics of their companion stars. Models of stellar evolution have difficulty producing black holes in close binaries with masses >10 solar masses, which is consistent with the fact that the most massive stellar black holes known so all have masses within 1 sigma of 10 solar masses. Here we report a mass of 15.65 +/- 1.45 solar masses for the black hole in the recently discovered system M33 X-7, which is located in the nearby galaxy Messier 33 (M33) and is the only known black hole that is in an eclipsing binary. In order to produce such a massive black hole, the progenitor star must have retained much of its outer envelope until after helium fusion in the core was completed. On the other hand, in order for the black hole to be in its present 3.45 day orbit about its 70.0 +/- 6.9 solar mass companion, there must have been a ``common envelope'' phase of evolution in which a significant amount of mass was lost from the system. We find the common envelope phase could not have occured in M33 X-7 unless the amount of mass lost from the progenitor during its evolution was an order of magnitude less than what is usually assumed in evolutionary models of massive stars.Comment: To appear in Nature October 18, 2007. Four figures (one color figure degraded). Differs slightly from published version. Supplementary Information follows in a separate postin

Structural analysis of the factors pertaining to attitudes toward and consciousness of organ donation : Comparison between Japanese and Americans

The purpose of this study is to analyze the background factors relating to opinions on organ donation through factorial and structural comparisons between Japanese and Americans. The data were obtained from responses to a questionnaire (371 Japanese and 41 Americans). The main findings are as follows: 1. Most of the factors, ‘a will for organ donation depending on a recipient’, ‘view of remains’, ‘understanding of brain death’ and so on showed significant differences between Japanese and Americans. 2. Japanese had a better understanding of brain death. On the other hand, the ratio of Americans who were willing to donate an organ was higher than that of Japanese. 3. It was revealed that “the approval of organ donation for the third person, not only for one's family” had an impact for having donor card showing the approval for organ donation. Furthermore, as underlying factors generating differences on organ transplant opinions, differences were found among Japanese between “approval of organ transplant” and the attitude assuming that oneself or a member of one's family was the person concerned with organ transplantation. There were also differences between Japanese and Americans on ideas about a view for life and death such as soul existence or view of remains. The argument for transplantation in Japan should consider these structural differences

Youth and Nigeria’s Internal Security Management

One of the major challenges confronting Nigeria is insecurity which hinders national development. The problem of insecurity includes menace of ethnic militias across the country, insurgency in the north, militancy in the Niger Delta, kidnapping, armed robbery and cultism all over the country. The government and other partners recognise that national security is a precondition for maintaining the survival, growth and development of a State. It is also well known that the army of unemployed and idle youth population of the country is the major group perpetrating these security problems across the country. Given the realisation of the government that the problem of insecurity needs to be tackled as panacea to the socio-economic development of the country, several solutions have been applied. The option of youth empowerment is believed to possess the capacity of not only keeping the youth busy but putting food on their table and thereby making incentive to engage in actions that promote insecurity unattractive. The youth empowerment programmes including the Amnesty Programme, YouWin and N-Power, among others, were some of the programmes implemented. What is the impact of these programmes as a strategy of managing insecurity in the country? To what extent are these programmes impacting on the socio-political and economic development of the country? What are the challenges in the implementation of these programmes? This chapter attempts to provide answers to these questions. The data used in this chapter were collected largely from documentary materials and analysed using descriptive analysis

Phono-spectrographic analysis of heart murmur in children

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Interferometric Observations of Rapidly Rotating Stars

Optical interferometry provides us with a unique opportunity to improve our understanding of stellar structure and evolution. Through direct observation of rotationally distorted photospheres at sub-milliarcsecond scales, we are now able to characterize latitude dependencies of stellar radius, temperature structure, and even energy transport. These detailed new views of stars are leading to revised thinking in a broad array of associated topics, such as spectroscopy, stellar evolution, and exoplanet detection. As newly advanced techniques and instrumentation mature, this topic in astronomy is poised to greatly expand in depth and influence.Comment: Accepted for publication in A&AR