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Ernest Mouchez

Ernest Amédée Barthélemy Mouchez was a French naval officer who became director of the Paris Observatory and launched the ill-fated Carte du Ciel project in 1887. Born in Madrid, Mouchez embarked on a career in the French Navy as an ensign in 1843; this was a period of relative international maritime peace and much of the navy's activities were dedicated to exploration and discovery. Mouchez was occupied on hydrographic studies along the coasts of Korea and South America, penetrating 320 km up the Paraguay River and exploring the Abrolhos Islands, he improved the practice of surveying at sea, adapting terrestrial instruments for naval use, was concerned with the problems of determining longitude. He developed the use of the theodolite and meridian telescope to improve the error in establishing longitude from around 30″ to 3–4″. Attaining the rank of post captain in 1868, he embarked on a series of expeditions to chart the coast of Algeria. However, in 1870, during the Franco-Prussian War, he was called upon to make an heroic defence of the port of Le Havre.

Returning to his Algerian survey, he brought it to a conclusion in 1873, when he was elected to the Bureau des Longitudes and, in the following year, was sponsored by the Académie des sciences to observe the transit of Venus from St. Paul Island in the Indian Ocean. On 9 December he made a sequence of superb photographic plates of the event. In 1875, the Académie elected him a member of the astronomy section and in 1878 he was promoted to rear admiral and awarded the role of director of the Paris Observatory; the observatory had fallen into disrepair and disrepute since the chaos of the 1870 war and the Paris Commune of 1871. Mouchez set about a programme of reconstruction but failed to persuade the government to fund a new observatory outside the centre of Paris. In 1887, he collaborated with Sir David Gill to host an international astronomical conference in Paris; the principal outcome of the conference was a multi-national project to compile and index a photographic atlas of the heavens, the Carte du Ciel.

The project consumed massive effort over several decades before it was rendered obsolete by modern astronomical methods. Mouchez died in Seine-et-Oise. A statue in Le Havre was unveiled by Benjamin Baillaud in 1921. A Street in Paris was given his name. Recherches sur la longitude de la côte orientale de l'Amérique du sud Rio de la Plata. Description et instructions nautiques Instructions nautiques sur les côtes d'Algérie Rapport annuel de l'Observatoire de Paris La photographie astronomique à l'Observatoire de Paris et de la Carte de ciel Instructions nautiques sur les côtes du Brésil Notice sur les travaux scientifiques de M. Mouchez, Paris Polybiblion, 2nd ser. 36, July–December. "Obituary: List of Fellows and Associates deceased during the year: Amédée Ernest Barthélemy Mouchez". Monthly Notices of the Royal Astronomical Society. 53: 226–229. Bibcode:1893MNRAS..53..226.. Doi:10.1093/mnras/53.4.226. "Carte du ciel", Encyclopædia Britannica, Deluxe CDROM edition Aubin, D.. "The fading star of the Paris Observatory in the nineteenth century: astronomers' urban culture of circulation and observation".

Osiris. 18: 79–100. Doi:10.1086/649378. Simpkins, D. M. "Mouchez, Ernest Barthélémy", in Gillespie, C. C. ed.. Dictionary of Scientific Biography. New York: Charles Scribner's Sons. ISBN 0-684-16970-3. Vapereau, G. Dictionnaire universel des contemporains, 5th ed. Paris Royal Society, Catalogue of Scientific Papers, IV 498, VIII 488, X 864. "Mouchez, Ernest Amédée Barthélemy". Imago Mundi. Archived from the original on 26 September 2007. Retrieved 27 August 2007

Immobilization (soil science)

Immobilization in soil science is the conversion of inorganic compounds to organic compounds by micro-organisms or plants, by which it is prevented from being accessible to plants. Immobilization is the opposite of mineralization where the inorganic nutrients are taken up by soil microbes making them unavailable for plant uptake. Immobilization process is a biological process controlled by bacteria that consume an inorganic nitrogen and for, amino acids and biological macromolecuels. Immobilization and mineralization happen continuously and concurrently whereby nitrogen of the decomposing system is transformed from inorganic to organic state by immobilization and back from organic to inorganic state by decay and mineralization. Whether nitrogen is mineralized or immobilized depends on the C/N ratio of the plant residues. For example, incorporating materials high in carbon to nitrogen ratio such as saw dust and straw will stimulate soil microbial activity,increase demand for nitrogen, leading to immobilization.

This is known as priming effect. In general plant residues entering the soil have too little nitrogen for the soil microbial population to convert all of the carbon into their cells. If the C:N ratio of the decomposing plant material is above about 30:1 the soil microbial population may take nitrogen in mineral form; this mineral nitrogen is said to be immobilized. Microorganisms out-compete plants for NH4+ and NO3- during immobilization, therefore plants can become nitrogen deficient; as carbon dioxide is released via decomposition the C:N ratio of the organic matter decreases, the microbial demand for mineral nitrogen is decreased. When the C:N ratio falls below about 25:1 further decomposition results in simultaneous mineralization of nitrogen, in excess to that required by the microbial population; when decomposition is complete soil mineral nitrogen will be higher than it was due to mineralization of the plant residue nitrogen. There are two mechanisms of nitrogen immobilization: Nitrogen accumulation in microbial biomass and accumulation of nitrogen in by-products of microbial activity.

Nitrogen Accumulation in by-products of microbial activity nitrogen accumulation in decaying plant debris follows a two-phase mechanism Following the initial leaching of soluble materials from fresh detritus, exoenzymes depolymerize the detritus substrate producing reactive carbohydrates, small peptides, amino acids, this is a period whereby microbial growth is rapid. With microbes converting substrate nitrogen and exogenous nitrogen into microbial biomass and exuded products of microbial activity. Mineralization Nitrogen cycle Nitrification The dictionary definition of immobilization at Wiktionary