Scuba diving

Scuba diving is a mode of underwater diving where the diver uses a self-contained underwater breathing apparatus, independent of surface supply, to breathe underwater. Scuba divers carry their own source of breathing gas compressed air, allowing them greater independence and freedom of movement than surface-supplied divers, longer underwater endurance than breath-hold divers. Although the use of compressed air is common, a new mixture called enriched air has been gaining popularity due to its benefit of reduced nitrogen intake during repetitive dives. Open circuit scuba systems discharge the breathing gas into the environment as it is exhaled, consist of one or more diving cylinders containing breathing gas at high pressure, supplied to the diver through a regulator, they may include additional cylinders for range extension, decompression gas or emergency breathing gas. Closed-circuit or semi-closed circuit rebreather scuba systems allow recycling of exhaled gases; the volume of gas used is reduced compared to that of open circuit, so a smaller cylinder or cylinders may be used for an equivalent dive duration.

Rebreathers extend. Scuba diving may be done recreationally or professionally in a number of applications, including scientific and public safety roles, but most commercial diving uses surface-supplied diving equipment when this is practicable. Scuba divers engaged in armed forces covert operations may be referred to as frogmen, combat divers or attack swimmers. A scuba diver moves underwater by using fins attached to the feet, but external propulsion can be provided by a diver propulsion vehicle, or a sled pulled from the surface. Other equipment includes a mask to improve underwater vision, exposure protection, equipment to control buoyancy, equipment related to the specific circumstances and purpose of the dive; some scuba divers use a snorkel. Scuba divers are trained in the procedures and skills appropriate to their level of certification by instructors affiliated to the diver certification organisations which issue these certifications; these include standard operating procedures for using the equipment and dealing with the general hazards of the underwater environment, emergency procedures for self-help and assistance of a equipped diver experiencing problems.

A minimum level of fitness and health is required by most training organisations, but a higher level of fitness may be appropriate for some applications. The history of scuba diving is linked with the history of scuba equipment. By the turn of the twentieth century, two basic architectures for underwater breathing apparatus had been pioneered. Closed circuit equipment was more adapted to scuba in the absence of reliable and economical high pressure gas storage vessels. By the mid twentieth century, high pressure cylinders were available and two systems for scuba had emerged: open-circuit scuba where the diver's exhaled breath is vented directly into the water, closed-circuit scuba where the carbon dioxide is removed from the diver's exhaled breath which has oxygen added and is recirculated. Oxygen rebreathers are depth-limited due to oxygen toxicity risk, which increases with depth, the available systems for mixed gas rebreathers were bulky and designed for use with diving helmets; the first commercially practical scuba rebreather was designed and built by the diving engineer Henry Fleuss in 1878, while working for Siebe Gorman in London.

His self contained breathing apparatus consisted of a rubber mask connected to a breathing bag, with an estimated 50–60% oxygen supplied from a copper tank and carbon dioxide scrubbed by passing it through a bundle of rope yarn soaked in a solution of caustic potash, the system giving a dive duration of up to about three hours. This apparatus had no way of measuring the gas composition during use. During the 1930s and all through World War II, the British and Germans developed and extensively used oxygen rebreathers to equip the first frogmen; the British adapted the Davis Submerged Escape Apparatus and the Germans adapted the Dräger submarine escape rebreathers, for their frogmen during the war. In the U. S. Major Christian J. Lambertsen invented an underwater free-swimming oxygen rebreather in 1939, accepted by the Office of Strategic Services. In 1952 he patented a modification of his apparatus, this time named SCUBA, which became the generic English word for autonomous breathing equipment for diving, for the activity using the equipment.

After World War II, military frogmen continued to use rebreathers since they do not make bubbles which would give away the presence of the divers. The high percentage of oxygen used by these early rebreather systems limited the depth at which they could be used due to the risk of convulsions caused by acute oxygen toxicity. Although a working demand regulator system had been invented in 1864 by Auguste Denayrouze and Benoît Rouquayrol, the first open-circuit scuba system developed in 1925 by Yves Le Prieur in France was a manually adjusted free-flow system with a low endurance, which limited its practical usefulness. In 1942, during th

Tawachiche West River

The Tawachiche West River is located in the Municipality of Lac-aux-Sables, in the administrative region of Mauricie, in the province of Quebec, Canada. Flowing in the Marmier, its watershed is part of the Batiscanie, in the area of the MRC Mékinac. Water of Tawachiche west river is going down from the north-west to south-east to empty into the Tawachiche River. Tawachiche West River is located in forest area; the surface of the river is frozen from November to April. Annually, the river flow is high during the spring thaw. Since the 18th century, logging was a major economic factor in this wilderness area. Nowadays, camping and outdoor activities are dominant: hunting, hiking or all-terrain vehicles, boats rides... The mouth of the Tawachiche west river is located near the reception office of the ZEC Tawachiche; the mouth is located at 5.8 km to the "Lake à l'Auguste", 8.4 km from the dam of "Little Lake Masketsi", 8.6 km from the dam of "Lac Profond", 8.6 km from the dam of Lake Terrien and 8,7 km from Lake Missionary.

The mouth is located 0.8 km from the former Audy railway station and 1.6 km from site of the former sawmill Veillet & Frères Ltée. The Tawachiche west river begins at the mouth of Lake Masketsi, which flows into the Little Lake Masketsi; the outlet of the latter empties into Lake Auguste. In its course, the river on its left bank catch water of the discharges of "Boileau Lake" and "Vieillotte Lake". From the mouth, up the stream, the road Tawachiche west follows the whole course of the river Tawachiche west. Upwards towards the northwest, the road passes near the "lake à l'Auguste", the "little lake Masketsi", Lake Masketsi, Lake Roberge, Lake Narcisse and Lake Faber. After crossing the lake Faber, Tawachiche west road meets a junction that connects the road Tawachiche is up to the Lake Price; this branch passes near lakes Calau, Puce, Lefebvre and "Lake à Mousse". Media related to Category:Tawachiche West River at Wikimedia Commons Batiscanie Marmier Zec Tawachiche Village of Hervey-JonctionMunicipalities: Lac-aux-Sables Sainte-Thècle Unorganized territory of Lac-Masketsi, QuebecZEC, Wildlife Sanctuary and parks: Portneuf Wildlife ReserveRivers: Rivière des Envies Tawachiche River Batiscan RiverRCM / MRC: Mékinac Regional County Municipality

Hernán López (footballer)

Hernán López Muñoz is an Argentine professional footballer who plays as a midfielder for River Plate. López played for Pacífico Villa del Parque, Juventud de Devoto, Agronomía, Cultural de Tapiales and Argentinos Juniors at youth level before joining the academy ranks of Primera División side River Plate in 2014, his breakthrough into senior football came on the final day of the 2018–19 campaign, with Marcelo Gallardo selecting the midfielder off the bench in a Primera División fixture versus Tigre on 7 April 2019. He came on with thirty-one minutes left in place of Jorge Carrascal, prior to scoring for 2–2 with four minutes remaining. López is a great-nephew of Diego Maradona, a former Argentine international footballer who won the 1986 FIFA World Cup in Mexico; as of 7 April 2019. Hernán López at Soccerway