Monday, 22 October, 2018

The Prenatal and New Birth Period

Posted on Monday, 10 February, 2014Sunday, 20 August, 2017 by Zheluo Cai

The formation of neurons begins very early in the human embryo. By five weeks after conception, the cells in the developing brain begin dividing rapidly to form the 100 billion or so neurons that an infant’s brain has at birth. Once formed, neurons begin to migrate to the correct location in the brain, and some synapses begin forming. (Neurons are specialized cells that process information. Synapse is an area between neurons that information is transmitted between them.)

Prenatal conditions — including temperature, pressure and fetal movements such as kicking— stimulate the development of synapses. Myelination of neurons also begins prenatally, starting with the neurons of the spinal cord and brain stem. (Myelin sheath (myelination) is a protective cover that surrounds nerve fibres that extend from neurons to facilitate speedier and more efficient communication between neurons.)

At birth, the infant brain weighs 2/3 to 3/4 pounds (300-350 grams). Connections in the parts of the brain that control basic survival and reflexes are already well developed, and myelination in those areas is nearly complete. The newborn begins a rapid period of brain growth. Synaptogenesis continues very rapidly, with neurons in all parts of the brain making trillions of connections. Myelination continues in most parts of the brain. The neurons controlling hearing and vision rapidly become myelinated.

An average of 1,000,000 synapses per second are formed in the brain of the fetus and infant in the first two years of life. No wonder they are so tired and need so much help.

Tajik is a general designation for a wide range of native Persian-speaking people of Iranian origin, with current traditional homelands in present-day Tajikistan, Afghanistan and Uzbekistan. Not all Tajiks speak a variety of modern Persian. They may speak any one of the extant Iranian languages. For example, the Tajiks of China are actually Pamiris and speak the Eastern Iranian Pamiri languages and are distinct from more western Tajiks. They are concentrated in the Oxus Basin, the Farḡāna valley (Tajikistan and parts of Uzbekistan) and on both banks of the upper Oxus, i.e., the Pamir Mountains (Mountain Badaḵšān, in Tajikistan) and northeastern Afghanistan and western Afghanistan (Badaḵšān, Kābol, Herat, Balkh, Mazar-i-Sharif, Ghazni and other urban regions). Historically, the Tajiks were initially agriculturalists but urbanized rather early in ancient times as indicated by their role in the history of what later became Greater Khorasan. Several surviving ancient urban centres of the Tajik people include Herat, Samarkand, Bukhara, Khujand, and Kabul.

Young Stars in the Rho Ophiuchi Cloud.
Credit: NASA, JPL-Caltech, WISE Team. Dust clouds and embedded newborn stars glow at infrared wavelengths in this tantalizing false-colour composition from the Wide-field Infrared Survey Explorer. It is one of the closest star-forming regions of the Rho Ophiuchi cloud complex, some 400 light-years distant near the southern edge of the pronounceable constellation Ophiuchus. After forming along a large cloud of cold molecular hydrogen gas, young stars heat the surrounding dust to produce the infrared glow. Stars in the process of the formation called young stellar objects, are embedded in the compact pinkish nebulae. An exploration of the region in penetrating infrared light has detected emerging and newly formed stars whose average age is estimated to be a mere 300,000 years, which is extremely young compared to the Sun's age of 5 billion years. The prominent reddish nebula at the lower right surrounding the star Sigma Scorpii is a reflection nebula produced by dust scattering starlight. This view covers about 14 light-years at the estimated distance of the Rho Ophiuchi cloud.

The current flag of Myanmar was adopted on 21 October 2010. The new flag was introduced along with implementing changes to the country's name, which were laid out in the 2008 Constitution. The design of the flag has three horizontal stripes of yellow, green and red with a five-pointed white star in the middle. The three colours of the stripes are meant to symbolise solidarity, peace and tranquility, and courage and decisiveness. The white star that symbolised the Union of Burma.

The Elgin Marbles are a collection of Classical Greek marble sculptures made under the supervision of Phidias and his assistants in c. 447 to 438 BC; originally part of the temple of the Parthenon. From 1801 to 1812, agents of Thomas Bruce, 7th Earl of Elgin removed about half of the surviving sculptures and transported them to Britain. The half not removed is now displayed in the Acropolis Museum. In Britain, the acquisition of the collection was not supported by some, and the Earl's actions was likened to vandalism. Following a public debate in Parliament and its subsequent exoneration of Elgin, he sold the Marbles to the British government in 1816. They were then passed to the British Museum, where they are now on display in the purpose-built Duveen Gallery.

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