evidence supports the involvement of nitric oxide (no) in a varity of male reproductive processes such as spermatogenesis, spermiogenesis, sperm motion, sperm metabolism and sperm capacitation. however, low concentration of no is essential in biology and physiology of spermatozoa, but high amounts of no is toxic and has negative effects on sperm functions. on the other hand, it is established t...

1 Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark 2 Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden 3 Environmental Risk and Health Unit, Flemish Institute for Technological Research (VITO), Mol, Belgium 4 Environmental Chemistry (MILK), Health Effects Laboratory, Norwegian Institute for Air Research (N...

The contribution of different sources to the circumsolar dust cloud (known as the zodiacal cloud) can be deduced from diagnostic observations. We used the Spitzer Space Telescope to observe the diffuse thermal emission of the zodiacal cloud near the ecliptic. Several structures were identified in these observations, including previously known asteroid dust bands, which are thought to have been ...

Sandford et al. (Reports, 15 December 2006, p. 1720) reported on organic compounds captured from Comet 81P/Wild 2 by the Stardust spacecraft. We emphasize the difficulty in assigning the origin of compounds detected diffusely along particle impact tracks and show that rapid heating of aerogel that has never been exposed to cometary particle capture can generate complex aromatic molecules from l...

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much la...

The comet assay is a sensitive and versatile method for assessing DNA damage in cells. In the traditional version of the assay, there are many manual steps involved and few samples can be treated in one experiment. High throughput (HT) modifications have been developed during recent years, and they are reviewed and discussed. These modifications include accelerated scoring of comets; other impo...

The Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission observed comet C/2013 A1 (Siding Spring) three times at 3.4 μm and 4.6 μm as the comet approached Mars in 2014. The comet is an extremely interesting target since its close approach to Mars in late 2014 will be observed by various spacecraft in-situ. The observations were taken in 2014 Jan., Jul. and Sep. when the comet...

In this paper we report the first attempt to detect directly the intercombination transition lines of the C 2 molecule in a comet. Indeed, these transitions play a key role in the C 2 fluorescence process but had never been observed directly so far. We conducted an observational program with the Cerro Tololo Interamerican Observatory 4 m telescope, located in Chile, on September 15 th and 16 th...

We review the composition of Jupiter-family comet dust as inferred from infrared spectroscopy. We find that Jupiter-family comets have 10 μm silicate emission features with fluxes roughly 20–25% over the dust continuum (emission strength 1.20–1.25), similar to the weakest silicate features in Oort Cloud comets. We discuss the grain properties that change the silicate emission feature strength (...

The Core Outcome Measures in Effectiveness Trials (COMET) Initiative database is an international repository of studies relevant to the development of core outcome sets. By the end of 2013, it included a unique collection of 306 studies. The website is increasingly being used, with more than 12,000 visits in 2013 (a 55% increase over 2012), 8,369 unique visitors (a 53% increase) and 6,844 new v...