Secular variations in sperm quality: fact or science fiction?

Secular variations in sperm quality: fact or science fiction?

The debate concerning the possible degradation in human sperm quality began in the 1970s, was revived at the beginning of the 1990s and has continued to mobilize the scientific community ever since. After the meta-analysis by Carlsen et al. (1992) showing a decline in human semen quality over the last 50 years, several groups investigated the sperm characteristics of more or less homogeneous gr...

Renal stem cells: fact or science fiction?

The kidney is widely regarded as an organ without regenerative abilities. However, in recent years this dogma has been challenged on the basis of observations of kidney recovery following acute injury, and the identification of renal populations that demonstrate stem cell characteristics in various species. It is currently speculated that the human kidney can regenerate in some contexts, but th...

Quality of Service — Fact or Fiction ?

The QoS Service The default service offering associated with the Internet is a best-effort service, where the network treats all traffic in exactly the same way. There is no consistent service outcome from the Internet best-effort service model. When the load level is low, the network delivers a highquality service. The best-effort Internet does not deny entry to traffic, so as the load levels ...

Sonofusion – Fact or Fiction?

Sonoluminescence and Sonofusion phenomena may occur when vapor bubbles implode. This paper reviews the status of our understanding of the bubble dynamics involved in these interesting phenomena. In particular, the experimental and analytical evidence supporting the observed production of neutrons and tritium due to thermonuclear fusion within imploding bubble clusters is reviewed. Moreover, pot...

NFRs : Fact or Fiction ?